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WPRO-2202

FOUR'lH JOINT WHO/SPC SDIINAR ON FIIARIASIB AND VECTCIt CON'lROL

Sponsored. by the

WCJU.D HEAL'lH CJlGANIZATION RmIONAL Oll'PICE FOR 'lHE WESTmlN PACIFIC

and the

SOUTH PACIlI'IC OOJIIMISSION

Apia, W.stern Samoa 1-10 July 1974

lI'INAL REPORT

NOT FOR SALE

PRINTED AND DIS'mIBUTED

by the

RmIONAL OFFICE FOR '!HE WESTmlN PACIFIC of the World Health Organisation

Manila. Philippines July 1974

NOTE

The views expressed in this report are those of the advisers and participants at the seminar and do not necessarily reflect the policy of the World Health Organization.

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IN"lJtODUC'rI'ON •••••••••••••••••••••••••••••••••••••••••••••

REVIEW OF FILARIASIS PROGJWoIII!'.S IN THE SOU'lH PACIFIC •••••

EP:rDDaOLOGICAL MEmODS USED IN '!HE STUDY OF FILARIASIS •••

2.1 2.2 2·3 2.4

Standardization of method ••••••••••••••••••••••••••• Alternative methods of blood examination •••••••••••• ]mmunodiagno8t10 prooedur ••••••••••••••••••••••••••• Cl1n1oal Jlanit •• taUona •••••••••••••••.••••••••.••••

VECTOR SPECIES OF FILARIASIS. BIOHOlllICS AIm CON'1ROL ......

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3.1 Vector speci.a and bionomica •••••••••••••••••••••••• 4 ,.2 Vector control...................................... 6 3.3 Inaeotioide auaoeptibility test ••••••••••••••••••••• 7

MASS DRoo ADMINIS'lRATION IN '!HE CON'mOL OF FILARIASIS .... 4.1 4.2 4.3

Diethylcarbamazine citrate (DEC) .................... Organization of IlaSS drug adIa1nistration •••••••••••• Resul ts of mass drug administration •••••••••••••••••

StJR.G I ~ mEA'IMP2fT •••••••••••••••••••••••••••••••••••••••

RESEARCII IN Fn.aARIASIS •••••••••••••••••••••••••••••••••••

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6.1 Current research in the South Pacific ••••••••••••••• 10 6.2 'rl-eMa •••••••••••••••••••••••••••••••••••••••••••••• 11

PROSPECTS OF FILARIASIS CONTROL •••••••••••••••••••••••••• 12

8. DENGUE FEVER/DENOUE HA1!J4CRRHAGIC FEVER IN '!HE

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Boum PACIFIC •••••.••••••••••••••••••• 0 •••••••••••••••••• 12

8.1 current information ••••••••••••••••••••••••••••••••• 12 8.2 Vector survey and distribution •••••••••••••••••••••• 13 8 . .3 Vector control .••••••.••.••..••.•..•••.•.•...••.•..• 14

CONCLUSIONS . ............................................ . 15

ANNEX 1 LIST OF PARTICIPANTS ••••••••••••••••••••••••••• 19

ANNEX 2 LIST OF I>OCUMEN':MTIOH DIS'lRIBU'l'ED •••••••••••••• 23

ANNEX 3 - PRESENT S'n\TUS OF FILARIASIS AIm ITS OON'lROL IN 1!IE soom PACIJ'IC ••••••••••••••••••••••••••• 'Zl

CON'lmfl5 (oontinued)

ANNEX 4 - CLINICAL ABPEC'lB OJI' PILARIASIS ••••••••••••••• 33/34

ANNEX 5 - VECTORS OF FILARIASIS IN 'fHB SOU'DI PACIPIC.... 35/36

ANNEX 6 - CURRENT INlIORMA'l'ION ON DBNOUE PEVER/DENGUE BADl<JUUfAGIC l'BVlIR AND 'DfB DIS'lRIBUTION OF AEDES AmYP'l'I IN 'DIE SOU'lH PACIPIC ••••••••••• 37

TABLE 1 - SUJlMARY OF FILARIASIS COIi'lROL PROGRAMMIS AND CHANGES IN ENDBMICI'l'f IH '!BE SOU'lH PACIPIC •••••••••••••••••••••••••••••••••••••• 41/42

TABLE 2 - La-SO VALUES (.) OF INSECTICIDES OP AEDES liB4ALE IalQUI'l'OES IN '!BE SOU'lH PACIFIC ••••••• 43/44

TABLE 3 - LC-so VALUES (PPM) OF INSEC'l'ICIDES OF AEDES LARVAE IN '!BE SOU'l'H PACIFIC •••••••••••••••••• 45/46

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.IH'lRODUCTION

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'lbe Fourth Joint WHO/SouthPacific CoIIIIIission (SPe) Seminar on Filariasi. and Vector Control ... convened in Apia, We.tern Samoa, from 1 to 10 July 1974. Dr. Lanu Penaia ... elected Chairman, Dr. Anthony Polloi, Vice-Chairman and Dr. Peter F. Beales and Dr. Jona U. Mataik&, Rapporteurs.

In the opening ceremony. the Director of Health of Western Samoa welcomed the participants and brieny reviewed the excellent resul te obtained by the filariaeis control proJect, which was assisted by WHO and UNICEF. Addreues .ent by Dr. Francisco J. ny, Director of WHO Regional Office for the We.tern Pacific, and Mr. G.F.D. Betham, Secretary-General of the South Pacific Commis.ion, were read by their representatives. '!bey thanked the Goverraent of Western Samoa for ita generosity in acting as host to the seminar and providing transportation as well as secretarial assistance. In officially opening the seminar, the Honourable Prime Minister expres.ed the appreciation of his Govern­ment to WHO and the CoaIIIiuion for holding the seminar in Apia.

'lbe previous seminar on filariasis ('!be Seoond WHO/SPe Joint Seminar on Filariaeis) wu held al.o in Apia in August 1968. Sinoe then, many new developments have taken place and much information accumulated. '!bese include the results obtained from field trials on the praotioal usefulness of certain alternative methods of blood examination for miorofilariae, from preliminary field trials on vector control and fram maes drug administration in several oountries and territories.

Both WHO and the SPe are concerned with the recent outbreaks of dengue fever/dengue haemorrhagic fever in many countries and terri­tories in the South Pacific. It i., therefore, timely to discuss and promote progrlUlllles for the surveillance of the vector ,mosqui toes, particularly Aedes aeppti, and to plan long-term measures for veotor control.

During the pre.ent _ainar, ne. intonaation and findings were discussed by the participants from 1, oountries and territories (see Annex 1). A n\Dber of doO\aenta were distributed (see Annex 2). It is considered that they will .erve ae useful references. 'lbey are available for distribution to other filariaei_ workers who require more detailed information.

1. REVIEW OF FILARIASIS PROCIJWIIIIiS IN THE SOU'lH PACIFIC

Filariaeis ocoura in 12 of the 1, participating oountries and terri torie.. '!be exception i. GUU1 where there are no recorda to indicate that the di_eaee i. a public health problem. Systematic

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measures for the control of filariasis, mainly by mass drug adminis­tration with diethylcarbamazine citrate (DEC), supplemented by improved sanitation for .osquito control# have been undertaken in American Samoa, Cook Islands, Fiji, French PolyneSia, Gilbert and Ellice Islands, Truat Terri tory of the Paoifio Islands, Niue and Western Samoa. At the time of the last filariasis seminar in Apia in 1968, only four countries or territories had mass drug administration progr&llllles. In the Brit1ah Solomon Islands Protectorate, New Hebrides and Papua New Guinea, where the filariasis vectors are the same as those of malaria, DDT residual spraying has been oarried out for anti-malaria purpose.

The present status of filariasis in the South Pacific is briefly presented in Annex 3. Baaed on a completed questionnaire reoeived from 11 countries and terri tories, a 8\U1111&ry of filariasis control progr&llllles and changes in endemicity is given in Table 1.

2. EPIDEMIOLOGICAL ME'lHODS USED IN THE STUDY OF FILARIASIS

2.1 Standardization of methode

Emphasis was placed on the necessity to standardize both survey and reporting methods. The size and type of the sample are important. 'Ibis should be determined, preferably in collaboration with a statis­tician, aocording to the aims and objectives of the survey. As much data as possible should be collected# inoluding information on the work habita, sooial struoture and age and sex distribution of the population.

Blood should be taken at night between 1900 brs and 2400 bra until the periodioi ty in the study area becomes known. Surveys can be carried out during the day in areas of subperiod1c filariasis. A measured amount of blood muat be examined in every oase.

2.2 Alternative methode of blood e:xamination

'Ibe examination of stained thick blood films for the presence of miorofilariae 115 known to be unaatisractory and many low level deneities of miorofilariaelllia are likely to be missed by this method. Consequently, there has been a search for more aocurate and reliable methods.

2.2.1 Counting chamber method

This is a useful technique in areas where the identities of micro­filariae are known. 'Ibe loss of miorofilaria. reported when using thick blood films is considerably reduoed by this method. It has been used

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sucoessfUlly for surveys in East Atrioa. Improvised co~ting chambers oan be made uaing regular miorosoope slides and X-ray film or cellophane tape.

2.2.2 stimulation method

In areas of nocturnally periodic filariasis, administration of a 8I\Iall dose of DEC will st1Jaulate an inorease of microfllariae in the peripheral blood one hour later. '1h1s will enable blood surveys to be oarried out in the daytime. 'lbis method, however, can cause oonsiderable febrile reaotion in patients with srugia infections.

In Tahiti, attempts to stimulate with DEC and increase the microfilaria (mf) count in persons with low parasi taemias were unsuooessfUl in a study of 100 oases.

2.2.3 Membrane filter oonoentration method

'l.bis is believed to be perhape the lIoat effioient method of detecting microfilariae in peripheral blood, but its practicability is in doubt. Venous blood ia required and local populations, especially children, often resent venepunoture. In addition, depending on the size of the survey sample, this oan be a much more expensive method in time, cost of supplies and personnel, espeoially if a physician is required to take the blood sample, as is the cUe for children and. in sOllIe countries, for medioo-legal reasona.

'lbe efficiency of the membrane technique compared to Knott's technique of examining the sediment of haemolysed blood is oonsidered to be relatively the s.e.

Participants from eight oountries or territories stated that venepunoture teChniques would not be aooeptable as routine prooedures in their oountry or territory. Of the others, some felt that after adequate explanation, the population might accept such methods.

It was generally acoepted that the membrane filter technique is a sensitive method, but that it should be reserved for special studies only and not used for general aurvey purposes.

'lbe epidemiological signifioanoe of the very low microfilariemiae detected by this method ia not known. However, mosquitoes have been infected in the laboratory from such low density microfilaria carriers.

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2.3 Immunoaiagnostic prooedures

None of the iumunodiagnostic methods available at this time are specifio enough nor sufficiently understood to give reliable estimates of the prevalenoe or intensity of filarial infections in a population.

A t present Dirofilaria 1DIi tis antigen is used for illllluno­diagnostic skin tests. 'Ibis is because large quantities of adult Wuchereria bancrofti antigen are not readily available, but the possibility exists that in the future monkeys could be a valuable souroe ot suoh antigen. 12. 1.nIIIi tis is very Widely distributed throughout the Pacific and presumably the huIIIan population has been exposed to this parasite, making the value of positive akin tests doubtful. Persons With ooin lesions due to 12. 1DIIIitis are generally serologically negative and this is believed to be beoause they have lost their serologioal response. presumably due to the dea th of the worms.

2.4 Clinical manifestations

'!he value of enlarged lJlllPh nodes as a diagnostic Sign is doubtful because there are numerous causes of enlargement other than filariasis. Clinioally it is very difficult, if not impossible, to distinguish lymphadenopathy due to filariaais from that due to other causes.

For reference, the general clinio&1 aspects of filariasis are sUlllllarized in Annex 4.

3. VECTOR SPECIES OF FILARIASIS, BIONOMICS AND CON'IROL

3.1 Vector species and bionomics

Baaed on up-to-date information available, a revised list of the vector species in the South Pacific is given in Annex 5.

3.1.1 In the periodic Wuchereria bancrofti areas

In the eastern areas of the South Pacific, the predominant vectors are the "Anopheles punotulatus" group. 'Ibey are night biters and usually breed in standing ground water. Anopheles farauti is widely distributed and consequently is one of the most important vectors in New Hebrides, Papua New Guinea and the Solomon Islands.

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'!be vector apeaie. i. UDkDaW.D _ OM ialaDd (Bellona) of the Solomon Ial.anda, where no anophel1ne lIO.qui toea have been found and f11ar1 .. 1s 1s pre.ent. Manaonia .. laa..ienaia was found naturally infeoted with!!. bancrot'U on Guadaloanal during World War II. Culex p1piens fati§!!!! ia reported .. an iIIportant vector in the caroline Islands. the Mar1anu. Gilbert Ialands and Nauru.

3.1.2 In the aubper1odio yP*nJ1t _S0rti areas

In the aubper1ed10 !!. banerotti are .. ot the South Pa01f10, the Aedes sou1;ellVia group 1a the lI&Jor veotor. '!here are many 1nd1pnous speo1e., of Which some are cona1dered vectors only on epidem101ogical grouncia. 'lbe whole !!.. sou1;ellar1a group is 1n need of taxonomio revisioD, including!!.. polp!1eDail 1Ih1ch 18 widely di.tributed and predominant and ia the principal vector tor mo.t of the area. A t least one UDdeacr1bed lpeoies, the only Mlllber of the group on N1utoputapu and Tafab1 Islands in Tonp. is an eff10ient veotor in that hyperendemic area.

In both the larger Fijian Ialands and 1n the Suoaa, there azoe local spec1ea (!!. paeudoaoutellar1a and !!. upolenais), closely related to !!.. polpesienais, that are found in the interior portions of the islanda. It was MIltioned that!!.. polesienais 1s seldom found more than half a 1I11e troIa the aout on Vi tilevu in FiJ 1. '!be Ae. soutellar1s group breeds ma1nly in oontainers, utilising tree holes, coconuts, rook holea, artit1c1al oontainers of all types, as well as orab holea (Which in acme areaa are responsible for extremely h1gh denai ties) and, on ooou10n, eva leafax11s (espec1ally where there are no 1nd1pnou leat-u1l breeders).

'!be b1 t1ag oyole of !!.. peeudoaoutellaris is s1m11ar to that of .!!. polznes1ena1s, .. revealed recently by the studies in Fiji. It was alao oont1rllecl that!!.. (Oohlerotatua) vigilax bites mainly at night. '!be interval between blood -.ala of !!. polynes1ens1s 1n Fiji 1a three and a half d&7a, .. ahown by marking and releaaing exper1-ments.

In the .. stern portion ot the lubJteriod1c !!. banoroft1 area, scme apeci .. of &D9ther group ot Aedea ..-qui to. the kochi group of the aubpnus P1nlaf!. are etteative vectors. TWo species, Ae. SallOazlUS and!!.. fiJiena1a, which are n1ght-biting and leaf-axil breeding lIOaqu1 toea. are ot local 1IIpor1;ance.

In the New Caledonia and Loyalty Isl&Dda, the vector 1s !!. v1gllax, a bracldah-.ter breeder in mangrove awamp. and salt marshes, as well as in ground pools and rook hole ••

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The praotioal importance of Q.£. fatigans in the transmission of subperiodic !. banorotti is doubtf'Ul. although it was reported that this mosquito can be a vector ot this fonn of filariasis to • limited extent in Tahiti and Fiji.

3.2 Veotor control

It is not poaaible to outline a single control measure against all the filariasis vectors. which involve many IDOsqui to species and have a very diverse ecology.

3.2.1 Control of "Anopheles punctulatua" grOUP

'!beoretlcally, indoor reaidual spray1ng of DDT for antl-malarla purpose should interrupt, or at least reduce. the transmission of filariasis by this group of moaqui toea. An as.eaament of i te effect­ivenes. ia. therefore. required and is planned to be undertaken in the New Hebrides. Papua New Guinea and the Solomon Islands.

3.2.2 Control of C.g. fatileD!

The fundamental measure is efficient sanitation; larvicides can be used as a supplement. Biological and genetic control will not become operational in the near future.

3.2.3 Control of Aedes specie.

For Ae. polznes1ensis contz-ol, san! tation by .ouroe reduction and health education are of priary importance.

Small-scale field control trials with adulticides and larvioides were undertaken in Western Samoa. Satisfactory control could not be obtained. mainly because of inacces.ible and undetectable breeding si tes soattered in the bushes where it was difficult to apply larvi­cide.. In certain areas, crab holes are one of the important breeding si tes of Ae. polyneaiensis and. pose a technical problem for their control.

Investigations are being carried out in Western Samoa and Fiji on the pose1bili ty of using Toxorbplohites spp. and existing micro­bial pathogens including CoelOlDc.yces for biological control of vector mosqui toes. Trials may be undertaken using ultra-low volume (ULV) spraying by ground application for the oontrol of outdoor-resting vector mosquitoes.

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3.3 Inseotioide auaoeptibilitl teat

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Reoently, more tests bave been carried out for Aedes mosquitoes in the South Pacific. No development of resistance to inseotioides has been observed. Most of the test results, whioh bave not let been published, are giveJl in Tables 2 and 3.

4. MASS mUG AIJIIINIS'mATION IN TfIE CXIflROL OF FILARIASIS

Mass drug administration baa the advantage of covering both known and WllmOWD IIIf carriers. '!he number and. variety of anti­filariasis drugs suitable for .... admini.tration are extremely limited, and at pre.ent onll DEC is recOIIIDended for this purpose. To date, W. banorofti has not been shown to exhibit any resistanoe to this drug, although in .ome oountriea, microfilariae persist at low den­sities following repeated treatments.

4.1 Diethylcarbamazine oitrate (DEC)

'!he preoise aotion of DEC on the various stages of !!. banorofti in man is not known. Bowver. it is believed to affeot micro filariae in such a manner as to make thea 1II0re su.oeptible to the natural de­fenoe mechanisms of the body. Miorofilariae are apparentll destroyed in the .pleen and liver. '!he drug is al.o believed to kill some adult worms. and to permanently or temporarill .ter1lize others. Within 12-24 hours of giving the drug. III1crofilariae are affeoted and in some cases el1minated. but &8 early as five IIIOnths following treatment, microfilariae can reappear 1n the peripheral blood. In 1II&Il. the drug is exoreted through the renal syatem.

4.1.1 DiSadvantages of DEC

Drug reaotions may be due to the drug i teelf or the dead or injured m1crofilariae. or to adult worms. or to a cOlllbinat10n of them all.

'!he drug is a gastrio irritant, although less .0 than aspirin. and this mal be compounded When the side effeots are treated with aspirin. '!he drug bas a tranquilizing or hypnot1c effeot, oausing drowsiness. For thi. rauon, it is often reoommended that it should be admini.tered after the evening meal. and driving or other poten­tially dangerous oocupations should be restrioted. Other side effects include general weakness. lII&lai.e, headache. giddiness, fever, lympha­deni tis, nausea and vom1 ting •

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DEC may preoipi tate aigDII of the dise .. e suoh &8 swellings and hydrocele or it may exacerbate signa that are already present.

4.1.2 Advantaces of DEC

'!he drug is easily adIII101stered orally in tablet or in syrup form. It reduces or e11Jllinates lliorofllariae from the peripheral blood, thereby reduoing the possibility of transmission.

'!he antihelminthic ettecta ot the drug can reduce the prevalenoe of ascariasis and other helm1nthes, with the exception of hookworm, in the population during a maas treatment oampaign.

4.1.3 Formulations and dosage

Medicated salt and toodstutts suoh .. soup and orange Juice have been utilised for the III&SS distribution of DEC in some parts of the world, but this can be efteotive only in those areas where strict oontrol of the salt or toodatldt oan be maintained.

For mass drug adminiatration, the reoOlDended dosage of DEC is 4-6 mg/.kg body weight in a min1Jllull total dosage reg1Jlle of 72 mg/.kg body Weight. Spaced doses bave been tound to be more effective than consecutive daily doses, and are also more oonvenient for mass treat­ment programmes.

4.2 organization of mass drug adIII1nistration

A census should be taken and simultaneously a treatment register should be prepared to inolude personal identifioation, body weight, and number of tablets to be oons\.D8d by eaoh individual. A preli­minary sample survey from the whole country or pilot study area should be carried out prior to mass drug adIIinistration. A post-treatment survey should be made using the same methods.

'lbe most effeotive means of distributing drug on a mass scale would appear to be to utilise a ocnbination ot medical authorities and voluntary health workers, the former supervising the programme. campaigns should be of short duration to ensure oontinuing interest on the part of the volunteer workers and the public. Eaoh distri­bution team should be limited to two to five persons with one indi­vidual as leader. Health education is very important and every available media should be utilised.

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Some groupe should be excluded :f'rom the mass treatment campa1gn. Among them would be the chron1cally sick. the aged. infanta and those with drug idiosyncracies. Another grouP. such as the acutely sick and pregnant women. may need to have treatment postponed. As the programme progresses, adjustments must be made to account for the natural mortali t;y and movement of populations.

4.3 Results of mass drug administration

In the countries and territories where mus drug administra­tion has been undertaken. the mf rates and densities have been greatly reduced. Detailed information :f'r0lll theae countries and territories is not available either to workers in the Pacific area or to those else­where. 'lbe results are. therefore. given in Annex 3.

In French Polynesia and American Semoa. there is a small group of people who are recurrent or persistent mf carriers despite repeated treatment with DEC. The reason is not known.

A study on the efficacy of a single doae of DEC was carried out in French Polynesia. and the results are prom1sing.

Now that two rounds of maea treatment w1th DEC have been com­pleted in the Samoas with a consequent reduction in the mf rates and mean mf densities, the migration of carriers with high densities into these areas oonstitutes a problem.

There is oonsiderable movement of the population in the Paoifio. not only within. but &1so between the oountries and territories. 'lbe most movement oocurs between Alllerioan Samoa and Western Samoa, and between American Samoa and the United states of America.

In Amerioan Samoa. for sOllIe ;years now. regulations have been in force requiring treawent at the port of entry of infected persons from Western Samoa and Tonga. '!heae regulations have reoently been ohanged in oo-operation with the authorities of Western Samoa, and now only documentary evidenoe is required that an incoming passenger :f'rom a filariasis endemio area is IIIf negative. 'lbis requirement does not restriot the :f'ree IIIOvement of people between terri tories, but any person not producing adequate dooumentation on entering Amerioan Samoa, is required to undergo teating and treatment if found. to be an mf oarrier.

Western Samoa and Niue are expeoted to adopt similar regulations in the near future.

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5. StflGICAL 'lREA'1t4ENT

For many 7ears s\U'geons have been operating on hydrooele and elephantiasis of the male genitalia throughout the Paoific Islands. In Western Samoa, for example, approximate17 100-200 hydrocele operations are performed ever;r year.

There remains a group of indiv1duals with elephant1as1s of the limbs, who are ser10us17 hand1capped ph7a1cal17 and so01&117. In Western Semoa, 24 oases of elephant1asis of the limbs due to filariasis have been treated surgically using Thompson's teohnique. After one to four years of post-operative observation, the results for 75f, of these patients have been assessed as "good" or "satisfaotory".

Thompson's teohnique consists essenti&117 of inserting a flap of dennis, denuded of its epidermis, into a oonvenientl7 located intramusoular orevice, so that it is in contaot with unobstruoted perivascular lymphatios, after the oedematous fibro-fatty tissues and fasoia have been exoised. This operation results in improved lymph flow.

Surgical correotion of elephantiasis is cons1dered to be a necessary adJunct to a suocessfUl filariasis control programme.

6. RESEARCH IN FIIARIASIS

6.1 current research in the South Paoifio

6.1.1 Fluotuation in at density

Investigations in French Polynesia have shown a regular flUc­tuation of mf densi tie. of subperiod1o filariasis in man, with a peak oocurring approximate17 ever;r 80 days. Further studies showed two osoillations, one with a seven-day oyole, believed to be due to host factors, and the other an eleven-da7 cycle, believed to be due to parasi te faotors. The.e synchronized ever;r 77 da7., which would explain the peak observed in the initial studies. The same pheno­menon baa been found in rodents and oats. The signifioanoe of this in relation to mosquito biting habits is not known.

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6.1.2 Veotor transmission

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In natural veotors ot tilariasis, the parasitic reduction (i.e., the ditferenee· between the inpllt of IIicrotilariae and the output of the infective larvae) is never proportional. It appears that two main t:ypes occur in the vector mosquitoes - "limitation" for Aedes and CUlex and "faoilitation" for Anopheles. Studies are being oarried out in Tahiti to oonat.ruot a math .... tioal model to describe this phenomenon.

6.2 Tl'enda

Over the past several years studies in filariasis have oentred upon three major areas:

(a) surveys of human filariasis;

(b) zoonotio filariasis; and

(0) development of an1mal models for studies of filarial biolo87, pathology and oheIIot.hm'apy.

6.2.1 survey! of human filariasis

'!here has been increased interest in surv.Ting human populations becau.e of the introduction of newer, more sophisticated methods for detecting the presence of microt1lariae. '!hese methods, inoluding the counting chulber and the ID8IIIbrane filter conoentration techniques, detect low levels of microfilaremia whioh are often missed by thick film examination. Work is also oontinuing on improving and developing serodiagpostio tests.

6.2.2 Zoonotic. filari .. is

Increasing attention has been paid to. filarial worms which are normally parasites of &DiMls but which ....,. cause diseases in man. Examples of these are Dirofilaria 1mm1t1a found normally in dogs, £. repens in dogs and Onchocerca speoies in cattle and horses.

6.2.} Animal models

Much effort has gone into finding a suitable animal in which to establish~. bancrofti so that oomprehensive studies of the parasite may be aooomplished. To date oats, dogs, pr1lllates and rodents have been the an1IIJa.ls mainly utilized. Unfortunately,~. banorofti cannot be satis­factorily established in gerbils. However, reoent work with monkeys shows promising results.

WPR/F1l/12 Page 12

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7. PROSPECTS OF FILARIASIS CON'lROL

When reviewing the future of filariasis control. one must consider direct attack on the parasites. as well as vector control.

As mentioned earlier. when discussing the control of the "Anopheles punctulatus" grouP. DDT residual spraying for anti-malarial purpose should. at the same time. control filariasis. Basic sanitation is important in controlling Q.E. fatigans and!!. polynesiensis. So far. there is no single sui table method for the control of outdoor-res ting mosquitoes or larvae of oertain vector speoies of Aedes. Biological and genetio control will not become operational in the near future. If eoonomioally feasible. all available practioal means of vector control should be utilized.

The only suitable drug available to attack the parasite is DEC. Mass treatment utilizing this drug in various regimes seems effective in reducing the mf rate so that mosquitoes cannot become infected. The single dose treatment regime discussed earlier may well be sufficient to eliminate the parasite in a large percentage of carriers. Mass treatment programmes must be economically feasible; and before consider­ing the need for a subsequent round of drug distribution, a thorough search should be made for mf carriers so that they may be treated.

It may be that DEC alone is unable to interrupt transmission in areas with high densities of effioient vector mosquitoes and, therefore. vector control methods. as practioal and feasible. should be also utilized.

8. DENGUE FEVER!DENGUE HAJM)RRHAGIC FEVER IN '!HE soum PACIFIC

8.1 Current information

During World War II. major epidemics of dengue fever occurred in at least 12 of the 19 South Pacific countries and territories. After that, no epidemics were reported for 20 years until outbreaks of dengue type 3 ooourred in French Polynesia in 1964 and 1969. In early 1971, simultaneous outbreaks in Fiji and Tahiti heralded a series of pan-Pacific epidemics. Dengue type 2 was oonfirmed in the laboratory from nine sepa­rate outbreaks. Small numbers of oases have since been reported regularly from Fiji and Tahiti.

WPR/Fil/12 Page 13

A low level epidemic of dengue type 2 is currently in progress in the Kingdom of Tonga. Gases of dengue type 3 have just been confirmed in the Marshall Islands, while an unknown type of dengue is active at present in Nauru.

Dengue fever with haemorrhagic manifestations has been reported in a range of less than l~ up to 25% of clinical cases. During the recent epidemic on Niue, there were at least 23 cases with severe haemorrhagic manifestations, resulting in 12 deaths.

Detailed information on dengue fever/dengue haemorrhagic fever in the South Pacific is given in Annex 6.

Because of these recent epidemics, a special has been started by the South Pacific ComIIIission. project include:

project on dengue '111e aims of this

(a) the establishment of a centre for gathering and disseminating information on dengue occurrence and research;

(b) the support of serological services to determine the susceptibility level of different populations, and research on the various strains and levels of viraemia associated.with different types of clinical illness;

(c) the support of vector surveillance and control; and

(d) technioal assistance in controlling outbreaks.

'111is project is being conducted in co-operation with WHO, the Pasteur Institutes of Paris and New caledonia and the Insti tut de Recherches M4dioales "LcDuis Malard4" of French Polynesia.

WHO entomologists have also assisted in veotor surveillance in certsin countries and territories in the South Pacific. During the present seminar, technical guides on the diagnosis, treatment, sur­veillance and control of dengue haemorrhagio fever and ita vector mosquitoes were distributed. These were prepared during the first meeting of the WHO Technical Advisory Colllll1 ttee on Dengue Haemorrhagic Fever held in Manila in March 1974.

8.2 Vector survey and distribution

Usually, the occurrenoe of an outbreak of dengue fever/dengue haemorrhagic fever is associated with!!.. aegypti. !!.. albopictus is considered a vector of classical dengue fever and is, most probably,

WPR/F1l/12 Page 14

the vector of dengue in wild monkeys. Epidemiological observations have suggested that Ae. scutellaris serves as a vector of dengue in Papua New Guinea and Ae. polynesiensis in French Polynesia. However, during the recent outbreak in Rabaul, papua New Guinea, ~. aegypti constituted 71~ of all the mosquito larvae collected. Ae. cooki was suspected to be a vector during the recent outbreak of dengue fever/ dengue haemorrhagic fever on Niue.

It is of the utmost importance to have basic information on the distribution and density of Ae. aegypti, as well as its closely-related Stegomyia species. Standardization of vector surveillance methods is necessary for global surveillanoe, so that data from different countries are comparable.

In oountries or areas where only one speoies occurs or predominates, the single-larva-per-container collecting method is reoommended. In areas where basic information on veotor species distribution is still lacking, it is advisable to oollect 10 larvae per water-holding oontainer. Another alternative method is to colleot a single larva, using the single­larva-per-oontainer colleoting method, and then to oolleot a few more larvae from the same oontainer and place them into a separate collecting bottle for detailed studies.

'!he following indices at least should be obtained:

(1) "Breteau index" - number of positive oontainers per hundred houses;

(2) "Premise index" - percentage of houses positive for larvae.

A search for larvae should be made in all the water-holding con­tainers inside and outside the house, including automobile tyres, dis­carded tins, etc. Other possible breeding sites in schools, hospitals, ohurches and cemeteries should be searched. Roof gutters and plant containers close to houses should also be examined.

Ae. aegypti is widely distributed in the South Pacific. up-to-date information on its distribution in individual countries and territories is given in Annex 6.

8.3 Vector oontrol

'!here are several methods of controlling Ae. aegypti whether required for a long-term programme or for an emergenoy when an epidemic of de~e haemorrhagic fever occurs.

,

WPR/F11/12 Page 15

'!be fundamental measure for a long-term control progI'Ullle is basio sanitation through souroe reduction and health education. If necessary. it can be supplemented by applyins Abate 1'; sand granule at a dosage of 1 ppm as a larvicide. Epidemiologioal and entomological surveillance data should be used to direct control operations to those areas which have the highest veotor densities and previous histories of outbreaks.

In an emergency. two grOUI¥1 applioations of ULV spraying with technioal malathion or fenitrothion at 438 ml/ha using vehiole-mounted or portable aerosol equipment should be applied at an interval of 10 days. Priority should be given to those areas with concentrated cases and to nearby schools and hospitals.

When and if neoessary. ULV spraying can be applied by aircraft.

9. CONCLUSIONS

After having reviewed the recommendations made during the filariasis seminar held in Apia in 1968. the following conolusions were reached:

9.1 At least. one round of mass drug administration with diethylcarba­mazine citrate at a dosage of 4 to 6 mg/kg body weight should be used in each country/territory where filariasis is known to occur. 'lbe total dosage g1 ven should be not less than 72 mg/kg body weight. 'lbe timing of the dosage should be detennined by local conditione. Post-treatment survey and retreatment should be perfonned as outlined in the 'lbird Report of the WHO Expert CCIIII1i ttee on Filariasis. l '!he resurvey may include a sample survey using a ooncentration method;

9.2 WHO and the SPC should cOllllider supporting further large-scale trials of a single dose of diethylcarbamazine citrate given at long intervals. Sui table areas for such trials can be fOUI¥1 in the Kingdom of Tonga;

9.3 Studies should be undertaken on the epidemiological significance of very low levels of microfilariaemia. western Samoa is a sui table area for suoh investigatioDII;

9.4 FUrther studies should be oonducted on other methods of filariasis diagnosis. including serological and immunologioal methods;

lwI.d Hlth Drg. techn. Rep. Ber •• 1974. 542

WPR/F1l/12 Page 16

9.5 Surgical treatment of hydrocele and elephantiasis of the extre­mities and genitalia now gives more promising results and surgeons should be encouraged to use the latest techniques. Information regard­ing these teohniques should be readily available. and they should be demonstrated at suitable oentres;

9.6 There should be greater co-operation between countries and terri­tories to ensure that migrants are not microfilaria carriers;

9.7 When possible. surveys for the identification of animal filariae should be carried out;

9.8 More investigations should be carried out on the determination/ confirmation and bionomios of filariasis veotors. as well as methods for their oontrol;

9.9 A reference colleotion of inseots of publio health importanoe in the South Paoifio should be established in a suitable centre. e.g •• the Insti tut de Recherches med10ales "Louis MalardC§", Papeete, Tahiti. This Institute is also able to provide train1ng facilities, partioularly for mosquito identifioation. A note on methods of oollection and the des­patoh of specimens should be prepared and sent to entomologioal workers in the South Pacific;

9.10 It is of the utmost importance to have oontinuous basic inform­ation on the distribution and density of Ae. aegypti,as well as other Stegomyia speoies involved in dengue fevertdengue haemorrhagic fever transmission. The information should inolude the Breteau and premise indioes of vector species and should be tranami tted to WHO and the SPC for oorrelation and dissemination;

9.11 National progrlllllDes on veotor oontrol on a long-term basis should be established as soon as possible in oountries and territories where there is a risk of an outbreak of dengue fever/dengue haemorrhagic fever. If possible, equipment for ULV spr&71ng and inseotioides of ULV grade should be made available. particularly for emergency use;

9.12 Training courses on the surveillanoe and oontrol of veotor-borne diseases in the South Pacifio should be organised and conducted by WHO/SPC when requested by the countries and territories;

9.13 The SPC should be requested to publish a teohnioal guide booklet for the use of publio works engineers. health inspeotors, architeots, contraotors, etc., on the effective measures to be taken and the method­ology to be used in avoiding the oreation of new breeding sites for veotor mosquitoes. and also for the destruction or alteration of exist­ing s1 tes in all rural and town development programmes;

•

WPR/F1l/12 Page 17/18

9.14 There i8 a great need for the exchange of epidemiologioal and technioal information on vector-borne disease in the South Paoifio. It i8 essential for oountries and territories to provide WHO and the SPC with the neoe8sary information as soon as possible for oorrelation and dis8emination.

9.15 Administrative and logistic support should be provided by governments so that oontrol measures may be carried out more effeot­ively.

Countries or Territories

American Samoa

British Solomon Islands Protectorate

Cook Islands

Fiji

French Polynesia

Gilbert a: Ellice Islands

Guam

LIST OF PARTICIPANTS

Name of Partioipant

Dr Peter 11'. Beales

Dr Noto Siliga

Dr R.R. Webber

Dr N. Tau

Dr JOM U. Mataika

Mr Wilisoni C&g1ma1vei

Dr Jaoques Laigret

Dr Tomasi Puapua

Mr Richard A. Mackie

WPRiFil/l2 Page 19

ANNEX 1

Title and Otficial Address

Direotor of Medical Servioes Department of Medical

Services pago Pago 96199

Public Health Offioer Department of Medioal

Servioes Pago pago 96199

Medical Officer Medi cal Department Honiara

Director of Health Department of Health Ministry of Social Services Rarotonga

Medioal Officer Medioal ·Department Suva

Heal th Inspeotor Medioal Department Suva

Directeur de la San~ publique B.P. 611 Papeete Tah1ti

Medical Offioer Medioal Department Bikenibeu Tarawa

Public Health Entomologist Department of Public Health

and Social Services P.O. Box 2816 Agana

WPR/Fil/12 Page 20

Countries or Territories

New Hebrides

Niue

Papua New Guinea

Tonga

Trust Territory of the Pacific Isiands

Western Samoa

Consul tants

Professor Lawrence R. Ash

Professor J.F.B. Edeson

Name of Participant

Dr Raoul t Ra tard

Mr Punapa Eri ok

Dr.N. Tavll

Mr Stephen Ani

Mr Etuate Sakalia

Dr Anthony Polloi

Dr Lanu Penaia

Dr Wal ter Venneulen

ANNEX 1 (cant 'd)

Title and Official Address

Medical Officer in charge of malaria and filariasis control

P.O. Box 177 Vila

Health Inspector Heal th Department Alofi

Assistant Director for malaria control services

Department of Public Health Konedobu

Public Health Inspector Public Health Department Konedobu

Heal th Inspector rllinistry of Health Nuku'alofa

Medical Officer MacDonald Memorial Hospital P.O. Box 39 Koror, Palau Is. 96940

Filariasis Control Offic~r Heal th Department Apia

Surgeon Specialist Heal th Department Apia.

Division of Epidemiology School of Public Health University of California Los Angeles, California 90024 Uni ted States of America (SPC Consultant)

Department of Tropi cal Health American University of Beirut Beirut, Lebanon (WHO Consultant)

•

Observers

Dr Pierre Fauran

Dr J. Mouchet

Dr F. Neva

Mr G. Plchon

Dr J .S. P111a1

Dr F. ROOhain

Mr Fo1a Sone

EntclDolOS1st.e luat1 tutput.eur B.P. 61 Houmea. He. Caledonia

D1reoteur

WPR/P11/l2 Page 21

ANHEX 1 (oont.'d)

Serv10es so1entif1ques centraux Off1ce de la Recherche sc1entif1que

et teohnique outre-mer (ORSTOM) ~140 !" Bo~. Franoe

~.t. Laboratory of Parasitic Diseases NIAID Nat10nal Institutes of Health Be1ihe8day. Maryland 20014 United States of Amerlca

EntomolOgiste Mdlcal Iuatltut de Recherches medlcalea

"Louis Malard4" B.P. ~ P&peete. Tah1ti.Frenoh Polynesia

Senior Leoturer in Microb1010gy UniYera1t7 01' Otago Medioal School Dunedin. Ne. Zealand (Obeerver for the Medical Research Counoil of New Zealand)

Epld4m101os1ate Servioe de V1rologle Inat.i tut Pasteur 25. rue du Dr Roux 75015~ Par1a, France

Publio Health Inspector F11ariasis Control Ap1a, Western Samoa

WPR/Fil/l2 Page 22

The Secretariat

Professor C.Y. Chow

Miss S. Exbroyat

Dr J. C. Hitchcock

Dr Dwayne Reed

Mr Claude Richard

Dr T. Suzuki

Dr Tin Maung Maung

Regional Adviser on Vector Biology and Control

ANNEX 1 (cont'd)

WHO Regional Office for the Western Pacific

P.O. Box 2932 Manila, Philippines (WHO Secretary)

Conference Officer South Pacific Commission P.O. Box D5 Noumea Cedex New Caledonia

Scientist' WHO Filariasis Research Project Nuku'alofa Tonga

Epidemiologist South Pacific Commission P.O. Box !)5 Noumea Cedex New Caledonia

Public Health Engineer South Pacific Commission P.O. Box D5 Noumea Cedex New Caledonia (SPC Secretary)

Scientist WHO Filariasis Advisory Team Suva, Fiji

Medical Officer WHO Filariasis Advisory Team Suva, Fiji

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t I . I I . I ! j

I I I

WPR/F11/l2 P&&e 23

ANNEX 2

LIST OF DOCtMBNTATION DIS'lRIBU'mll

A. On f1lar1as1s

WHO do~ntatioDf

(1) Chow, C.Y. (1913) Paoif10 Region.

Filariasis veotors in the Western (Unpubl1shed docnnent WPR/VBC/10)

(2) Chow, C.Y. a: T. 8U&Uk1 (1914) F11ariasis veotors and their oontrol in the South Pa01fio. (Unpub11shed work1ng do~nt WPR,/P11/9)

(3) Edeson, J .F.B. (1914) Ep1de1l101og1oal methods used 1n the studies ot filarias1. 1n general. (Unpublished work1ng dooument WPR/F11/B)

(4) Tin Maung Maung (1914) Clloioal aspeots of fl1ar1&818. (Unpubli.hed working dooument WPR/F11/l0)

(5) Tin Maung Maung (1914) Filariasi. oontrol by the application of .... drug admini.tration 1n Western Samoa, Ellice Islands and N1ue. (Unpubli.hed working dOCUlllent WPR/F1l/ll)

(6) World Health Organisation (1914) '1h1rd Report of the WHO Expert Ca.1ttee on Filarias18. WId lD.th Org. techno Rep. Ser., No. 542

Other unpubli.hed. dootaentation made available to the .... inar:

(7) Ash, L.R. (1914) Trends in f11ariasi. research and their applicabilit,y to filariasi. in the South Paoif10.

(8) Hitchoock, J.e. (1914) Filaria.ia aurveys in the Kingdom of Tonga.

(9) J(aeuffer, H, M. Merlin a: J. Laigret (1974) Study of a brute ant1senio extraot of Dirofilaria 1mmitia app11ed to the t.unologio d1agnoai. ot the l;plphatio fl1ariaa18 of Wuchereria bancrofti var. pacif1ca.

leop1ea can be obtained. tram WHO Regional Offioe for the Weatern PacifiC, P.O. Box 2932, Manila, Ph1l~ppin.a.

WPR/F1l/l2 Page 24

ANNEX 2 (cont'd)

(10) Laigret, J. (1974) Efficiency of 18 days treatment of diethylcarbamazine administered to microfilaria carriers.

(11) IAigret, J., M. Merlin, M. Chant.in. E. TUira &: G. Fagneaux (1974) Efficiency of one single dose of diethylcarba­mazine on microfilaremia of Wuchereria bancrofti micro­filaria carriers.

(12) Mataika. J.U. &: V. Cagimaivei (1974) Filariasis in Fiji.

(13) Pichon, G. (1974) Quantitat.ive aspects in filariaSis. 1. Parasit.ic reduction in the vector and possible influence on regulat.ion of parasite populat.ions.

(14) Vermeulen, W.J. (1974) New t.rends in surgery of elephantiasis due to filariasis.

(15) Webber, R.H. (1974) Filariasis in the Solomon Islands.

B. On dengue haemorrhagic fever

WHO documentation:

(1) Chow. C.Y. (1973) Aedes aegypt.i surveillance and control. with special reference to the South Pacific. (Unpub­lished document. WPR/VBC/l3)

(2) WHO (1974) Report. on the First. Meeting of the Technical Advisory Committee on Dengue Haemorrhagic Fever. Manila. Philippines, 5-7 March 1974

SPC documentation:

(3) SPC Dengue Newsletter, Vol. 1, July 1974

Other unpublished documentation made available to the seminar:

(4) Reed, D. (1974) Annotated bibliography of studies of control of Aedes aegypti during emergency sit.uat.ions.

(5) Suzuki, T. (1974) Tentative manual of Aedes aegypti survey by single-larva-per-container method in the South Pacific.

. I

. I

•

c. On veotor bio10R and control

WHO do~ntation:

WPR/F11/l2 Page 25/26

ANNEX 2 (conttd)

( 1 ) Chow, C. Y • (1970) 'l!le identification, biology and oontrol of fl.... (Unpublished document WPR/VBC/2)

(2) Chow, C.Y. (1972) Alternative .. thods of mo.quito oontro1. (Unpubl111hed dooument WPR/VBC/B)

(3) Chow, C.Y. (1972) Control of veotor. of II08quito-born. 41 ...... in the W •• tern Paoifio Region. (Unpubl1.hed doowaent WPR/VBC/9)

(4) Chow, C.Y. (1973) Biologr and oontrol of the oockroache •• (Unpubl1ahed. doOUll8nt WPR/VBC/l2)

(5) Dy, P.J. ct: C.Y. Olow (1971) Inaeota of publio health 1IIIportanoe in the W •• tern Pacifio Region. (Unpubli.hed doO\lllMtnt WPR/VBC/7)

Oth.r unpublished doou.entation made available to the .em1nar:

(6) Richard. C. (1974) Sanitary asin •• ring end mo.quito oontrol in the Bouth Pao1fio.

WPR/Fil/l2 Page 'Z7

ANNEX .3

PRESENT S'lJ.'ruS OF FILARIASIS AND ITS CON'lROL IN THE SOU'm PACIFIC

Amerioan Samoa

Surveys in 1962, before the first mass drug administration, revealed a mean mf rate of 21~ in 1000 persona examined in five selected pilot villages on the Island of Tutulla. Mass treatment using 6 mg/kg body weight of DEC was coamenced in 1963. A total dosage of 72 mg/kg body weight was administered over a period of one year. post-treatment surveys in 1965 indioated an mf rate of 3.ll~ in 1135 persona examined in the same five pilot villages. After the seoond round of mass drug administration, starting in 1965, the mf rate was O.~ out of 1053 persons examined in twelve villages.

The latest mass blood and clinioal surveys oonducted in 1970-1972, involving 79. 7~ of the total population, revealed an overall mf rate of O.9,C, a mean mf density in positive blood films of 10.7 per 20 ~ of blood, an elephantiasis rate of O.9,C, a recurrent lymphangitis rate of 1.l~. and a hydrocele rate of 2.1~. All persons found to be pos1tive were treated.

British Solomon Ialands Proteotorate

There is no specific anti-filariasis campaign, but the anti-malaria measures by DDT residual spraying carried out sinoe 1960 reduoed the mf rate from 25.l~ to 18.~ in one area after three years of spraying. In another area, after 10 years of spraying, the elephantias1s rate was 1.87~ and the mf rate was almost negligible; while in a similar area where spraying for only two years had been carried out, the elephantiasis rate was 0.81~, but the af rate was l5~.

Cook Islands

Mass drug administration started on the Island of Ai tutUi in 1968 reduced the mf rate from more than 3<>:' to o.~ in 1969 and O.~ in 1971.

Due to the geography of the islands and the population distribution, simultaneous aaas drug administration for the entire country has not been feasible. Thus, the follOwing five stase maaa treatment programme with DEC was begun in 19691 II

I I

WPR/F1l/12 Page 28

ANNEX 3 (cont'd)

Stage I: 1969-1971 - Southern part of Northern Island and Rotuma Islands

II: 1970-1972 - Northern part of Northern Island and Lau group

III: 1971-1973 - Eastern Division and Yasawa group

IV: 1972-1974 - Central Division

V: 1973-1975 - Western Division

The progr8lllDe continued for t.wo years in each of these five areas. The DEC dosage was 5 mg/kg body weight weekly for 6 weeks and then monthly for 22 months, with a total dosage of 140 mg/kg body weight. Post-treat­ment surveys of the 16-60 year age group only will be oarried out, as this group showed the highest mf rate before treatment. Sinoe the inception of mass drug administration, there has been a dramatic reduotion in hos­pital admissions due to filariasis. Post-treatment surveys show a decrease in mf rate to 1"; or less.

French Polynesia

Mass drug administration with DEC oommenced bet.ween 1950 and 1960 and has reduced the mf rate from 34,.; to 4% and the mf density from 78 to 11 per 20 am3 blood in posi ti ve films.

In 1963. only mf carriers were treated. resulting in an increase in prevalence to 7"; and in density to 80 mf/20 ~ of blood. Between 1966 and 1968. mass drug administration was carried out only in certain areas. From 1968 to 1972, quarterly mass drug administration and monthly distri­bution of the drug in schools was tried but the incidence remained static. From 1973 up to the present. quarterly mass drug administration has been undertaken. The mt rate is now 4.5"; and the density in positive blood films is 20 per 20 l1l1I3 blood.

A study on the efficacy of a single dose was carried out. with promising results. The study involved 143 mf carriers who were followed up for more than a year by taking the mean of two 20 mm3 blood. The results are as follows:

II II

"

" I'

II 11

I I

No. lit Months a:ft.er carriers No. Desative

DEC .xamined tor lit

'-4 months 1" ~

6-7 " 89 JJo

9-10 " .,., }8

12-1' " .30 18

WPR/F1l/l2 Page 29

ANNEX , (oont'd)

~ ot remaining No. positive carriers with rec1Uoed

tor IIf microtilaraemia

tR 77

49 80

}5 80

12 92

It was conoluded that after a single dole ot DEC. the mt rate was reduced by ~-~ over a period ot one year alId the average mt d.nsi ty and median oount were also reduoed. '!bos. carriere with low mf densities have beOOlH n.gative, and those with hip denaities are 8till p08Itive but with reduoed mt d.neiti.s. It ia. ther.tore, suggested that a single dose 111&7 be emplO)"ed monthly. quarterly, s.t-annually or annually. depending upon the ava1lab1l1 ty ot resouroes.

Gilbert and Ellioe Islands

On the 17 Gilbert is18llde. there does not appear to be a signifi­oant filariasis probl_. Howe".r. it is a maJor public health probl_ on the eight Ellice Ielanda. Mus drug adII1nistration was started in ltR2 with the assistance ot the WHO inter-oountry tilariasis adviaory team. Pre-treatment surveys in FUnafuti indicated an mf rate of 14.7% and an average mt oount per oarrier ot 85.5 per 20 ..., ot blood. A preliminary post-treatment survey ahows reduction ot the mf rate to 0.9.'.

Guam

'l'bere are no r.corda to indicate the ooe'urrenoe of W. banorotti at present. However. many dogs have been tound heavily infected with D. :lJIIDi tis.

New Hebrides

'!here is no speoifio anti-tilariasis oapa1gn. sinoe this disease ia not consid.red to be a maJor publio health probl.m at present. It has beoome apparent that the distribution ot t1lar1 .. is is patchy. wh.re malar1a reach.s the level ot _so-eDd_101tl', f1lariasis is endemic. In SCID. ar .... the mt rate was l~ with low lit densities and the .lephan­tiasis rate was 2-".

WPR/Fil/12 Page 30

Niue

ANNEX 3 (oont'd)

A mass drug administration progrltlllllle was 1aunohed. in mid-1972 With the assistance of the WHO inter-oountry filariasis advisory team. DEC was given at a dosage of 6 mg/kg body weight onoe a week for 12 weeks and followed by onoe a month for 12 months. Pre-treatment surveys re­vealed. an mf rate of 16."" and an average mf oount per carr1er of 30.6 per 20 =' of blood. Post-treatment surveys have now started.

papua New Guinea

There 1s no speo1fio ant1-filariasis programme. DDT residual spraying has been undertaken for anti-malaria purpose. A systematio study will be undertaken to evaluate the influence on filariasis of DDT indoor residual spraying used as an anti-malar1a measure.

Tonga

It is planned to start an anti-filariasis programme 1n 1975 or 1976. Blood and olinical surveys were started in 1968. Results obtained in a village (H1h1fo) on Niuatoputapu 1n 1970 showed an mf rate of 16.~ out of 680 persons examined. From the same village, 55 oh11dren (5 to 9 years of age) showed an mf rate of 71~ when blood was examined by the membrane f11ter ooncentrat1on technique, but only ~ when 60 -' of blood film taken s1mul taneously were examined. Of 2496 dissected mosquitoes (an undesoribed speoies of the ~. soutellaris group) from the same area, the inteotion rate of all stage larvae was about ~ and the infeotive rate l~.

Trust Terri tory of the Pao1f10 Islands

Of the numerous islands in this group, Palau and the other islands of Yap, Ponate and Truk have a significant filarias1s problem, Palau had. an mf rate of 12.~ 1n 1967. Maes drug administration with DEC at a dosage of 5 mg/.kg body weight once every other month for two years was started 1n 1970. The post-treatment survey revealed an mf rate of 0."" out of 1000 persona examined. Plana are being drawn up for mass drug administration in the other three groups of 1s1ands.

Western Samoa

The WHO/UNICEF ass1sted pilot project was established in 1905. The first round of mass-drug administration With DEC at 5 mg/kg body weight once a week for 6 weeks followed by a monthly dose for 12 months was oompleted in 1907. The average IS-dose coverage was 21~. Volunteers

I,

" 11

II II

WPR/F1l/l2 Page 31/32

ANNEX 3 (cont'd)

of the Women's Health Committees assisted in the distribution of the drug. The mf rate was reduoed from 19.~ to 1.63lC, am the average mf count from 58 per 20 mm3 blood film of positive carriers to 9. The second round with DEC at 6 mg/kg body weight, monthly for 12 months, was undertaken from January to December 1971 and has reduced the mf rate from 2.~ in 1969 to 0.1~ in 1973 and O.ll~ in April 1974.

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I .

CLINICAL ASPECTS OF FILARIASIS

WPR/Fll/12 Page 33/34

ANNEX 4-

There is still muoh to be learnt about the life cycle and patho­logy of !!. bancrofti in man.

The incubation period may vary but clinioal signs may be seen one month after infeotion. The pathogeneais of filariasis can be sUlDDariseci as stages of infl8lllll&tion. obstruction. hyperplasia and elephantiasis. mainly affeoting the lymphatic system initially but later involving other tissues.

The olinical man1festations oan be desoribed according to the pathologioal process. Thus. during the inflammatory stage. lymphan­gitiS. lymphadenitis. allergic man1festations, abscesses and sinuses develop.

In the obstructive stage, swelling of the tension ocours, this swelling pits on pressure. varioes and chyluria are signs of obstruction.

tissues due to fluid Hydrocele, lymphatic

In the hyperplastic stage, new tissues grow and hence true ele­phantiasis develops. Warty growths of the skin are seen.

Ultimately, fibrotio elephantiasis is the result.

Other signs of filariasis may be present and may mimic other diseaBes. Occult filariasis is a host reaction oausing hypereosino­philia and lesions in the lung. liver and spleen without oiroulating miorofilariae. Dead microfilariae may be found in lymph nodules.

VECTORS OF FILARIASIS IN THE SOUTH PACIFIC

WPR/Fil/l2 Page 35/36

ANNEX 5

American Samoa: ~ polynesiensis. Ae. samoanus. Ae. upolens1s

Cook Islands: Ae. polynes1ensis

Ellice Islands: Ae. polynesiensis

Fiji: Ae. 2olynesiensis. Ae. 2seudoscutellaris. Ae. fijiensis

French Pol~mes1a: Ae. polynesiensis

Futuna: Ae. futunae. Ae. polynesiensis

Gilbert Islands: Culex pipiens fatigans

Loyal ty Islands: Ae. vigilax

Nauru: f'E' fatigans

New Caledonia: ~. vigilax

New Hebrides: Anopheles farauti

Niue: Ae. cook1

Papua New Guinea: "Anopheles punctulatus" group

Rotuma: Ae. rotumae

Solomon Islands: "A. punctulatus" group

Tonga: Ae. tabu. Ae. tongae. Ae. ocean1cus. ~. ~.*

TTPI: f'E' fatigans

Wallis Islands: Ae. polynes1ens1s

Western Samoa: Ae. polynesiensis. Ae. samoanus. Ae. upolensis

~An undescribed species of the Ae. scutellaris group.

I ! •

WPR/F1l/l2 page 37

AHN!X 6

CURRENT DftI'OfIMATION ON DINOUB lI'IMIR/DEIIlUB HAlIDUUfAGIC FBVER AND '!HE DIS~OII OP ABD!I ABlYPn Dr 'lHB SOU'l'H PACIPIC

Amerioan Saaoa

A low level epideaio ooourred in 1972. '!'bere have been no oonfirllled cues since. !!. &!IlJ!U is proenl.ent.

A new dengue tever control seoUon has been establ.iehed to co-ordinate veotor s1U"VeUlanoe and control. sani t&Uon ... ures and health educaUon.

Sri Ush Solomon IslaDCia Proteotorate

'!here has been no reoopise4 epidea1c ot dengue sinoe World War II. NO!!. &emU was tCNDd Noentl7.

Cook IslaDCia

'.l!1ere has been DO reoop1se4 epidem.o ot dengue since 19Jf6. Surve,.s in Rarotonp ant1 AUutaki in Maroh 1974 revealed no Ae. aeppti.

Gilbert and Ellice IslaDcla

A aall outbreak ot denpe t". 2 ooGUl'Nd in 1972. 'l'be Breteau index ot!!. &eppU in Ii'UDatUU and Va1tupu in the Ellice Is1anda was 54 and 78 respective17. when surveJed in 1972.

A wide-spread epium.o ot ~e 't7Pe 2 bepu in 1971 and a aall llUIIber ot ... s oont1mle to be repar'Md.. !!. &emU has been tound in several localities. '!he Breteau ID11ex was 51 In Suva when it was eurve7ed in 1972. '!here is an aoUve denpe control progrMlle inoluding vector surveillanoe and control. a diqnoaUc v1rua laborato17 and an active lNbl1c health education and san1t&Uon proSl"-.

WPR/Fil/12 Page 38

French Polynesia

ANNEX 6

A dengue type 2 epidemic began in 1971 and a small number of cases continue to be reported. Ae. aeglPt~ is widely distributed in Tahiti and other Islands. There is a very active dengue control programme including vector surveillance, public health education and sanitation. A research laboratory is available for serological and virological studies.

Guam

There has been no recognized outbreak of dengue since 1947. No Ae. aegypt! has been found recently. There 1s a very act! ve general vector control programme.

New CAledonia

The last ep1demic occurred 1n 1972 and was oonfirmed as dengue type 2. The presenoe of Ae. aegypt1 was reported. There 1s currently an act1ve veotor control progr8.ll\llle. A virus laboratory will be esta­blished soon.

New Hebr1des

There was a oonf1rmed outbreak of dengue type 2 1n 1972. The Breteau index of Ae. aegypti in Ekipe was 163 when 1 t was surveyed 1n early 1973. Abate is be1ng used in sOllIe areas for the control of Ae. aegypt1 larvae.

An explosive epidemic of dengue type 2 oocurred in 1972. Ae. aegypti was found for the first time in August 1972 by the entomologist of the WHO 1nter-oountry filariasis advisory team.

Papua New Guinea

An epidemic of dengue type 2 oocurred in Rabaul in 1972, and some other ooastal areas may have been involved. ~. aegypti is present 1n several coastal areas.

Tonga

An epidemic of dengue type 2 is currently occurring. Ae. &egypti 1s prevalent. The control activities include pub11c health education and. sanitation.

, , • I

i • 1

•

•

•

•

Trust Terri tory of the Paoifio Islands

WPR/Fil/12 Page 39/40

ANNEX 6

'!bere has been DO reoognized. outbreak since World War II. except for a II1II&11 number of aue. of dengue type 1 which were reported in the Marshall Islanda in April 1974. ~. aeppU i8 present in all districts of the Terri tol'7.

Western Samoa

An outbreak of dengue tJPe 2 oocurred in 1972. A recent survey indicated the presenoe of ~. aeppU in 8011e parts of the main island. '!he Breteau index in Apia wu 25. when it was surveyed. in April 1973.

•

•

•

•

Changes in distribution of filariasis

Changes jn degree of endemici ty

Rural

area

Urban

area

Special filariasis service

National progr8Jlllle

Type of progranme

Mass drug

TABLE 1 - StM<IARY OF FILARIASIS ':X>N'IROL PROGRAMMES AND CHANGES IN ENDEMICITY IN 'IRE SOO'lH PACIFIC

. as c!:! II) ~

5 ..-1 H II) Q) c n

~ III +> II Z

0 S] .s:: II I.. Q) 'CI as ..-1 III g ~ Q) 0 ..-1 III Q) III ~ 0 .>< III ..-1 .Q..-1 ~ li Q) 50;; ~ II ~ M~ OM ...., 11M MM :;j

.li!rn o 1/1 o 1/1 i£ &~ ..... M Q) Q) ..... CIS ~ [:. II)H OH cr:.1 Z:X: Z Il.C

5 yrs - 0 - + - - - + - 0

10 yrs + + - + - - - + - 0

5 yrs + + + + + - 0 + + 0

10 yrs + + + 0 + - + 0 + 0

Decline + (?+) + + + + + ** 0 0

Increase +

Neither +

Decline + 0 + + + * .... 0 0

Increase

Neither + +

+ - + + + + + + - +

+ + + + + + + + - ***

N N N N N S S N - N

- - -administration + + + + + + 0

Vector control

Remarks:

anti-- ma- +

lar-ial spra3-ing

+ Yes = No

o N

No information supplied = Nationwide

S Selective

anti- anti - - + nala- - mala ['ial rial spray spra~-

ng ing

** No distinction between rural and urban areas in Niue *** = Starting in 1975

-

WPR/Fil/12 Page 41/42

C I.. 3 III

0

:l !ii 311)

+

0

+

0

+

+

+

+

N

+

-

•

Insecticide

DDT

dieldrin

• • •

WPR/F1l/l2 Page 43/44

TABLE 2 - LC-50 VALUES (%) OF INSECTICIDES OF AIDE<! FEMALE MOSOUITOES IN THE SOUl'H PACIFIC

Country Year Ae. 201ynes1ens18 !!. 28eudoscutel1ar18 !!. f1J1ens18 !!. aegypt1 References

Fiji 1959 0.70 0.72 0.24 1.28 Burnett and Ash (1961)

Fiji 1974 1.5 - - - Susuk1 (unpublished)

W. Samoa 1971 0.35 - - - Su&Uk1 aDd Sone (unpublished)

Fiji 1959 - 0.124 0.054 - Burnett and Ash (1961)

I

I

• •

Insecticide Country Year

DDT Fiji 1957-58

W. Samoa 1~0-71

dieldrin Fiji 1957-58

W. Samoa 1~0-71

)"-BHe Fiji 1957-58

malathion W. Samoa l~O-71

fenthion W. Samoa 1~0-71

feni trothion W. Samoa 1970-71

diazinon W. Samoa 1~0-71

Abate W. Samoa 1970-71

• • • • ..

WPR/Fil/12 Page 45/46

'OOU: 3 - LC-50 VALUES (PPM) OF INSECTICIDES OF AEDES LARVAE IN '!HE SOUTH PACIFIC

Ae. Ae. Ae. Ae. ~- 2seudo- fi- Ae. ocea- Ae. nesien- scute1- jien- samoa- ni- !!m-sis 1aris sis nus cua ti References

0.005 0.006 0.36 - - 0.012 Burnett and Ash (1961)

0.0031 - - 0.0040 0.0080 - Suzuki and Sone 0.011 - - 0.0064 - - . (unpublished)

- - - 0.0076 - -0.006 0.006 0.005 - - 0.008 Burnett and Ash (1961)

0.0043 - - 0.0015 0.0038 0.0083 Suzuld. and Sone 0.015 - - 0.0023 - - (unpublished)

0.009 0.020 0.007 - - 0.010 Burnett and Ash (1961)

0.051 - - 0.010 0.023 - Suzuki and Sone (unpublished)

0.0025 - - 0.0017 0.0028 - Suzuki and Sone (unpuJllished)

0.0062 - - 0.0042 0.0071 - Suzuki and Sone (unpublished)

0.042 - - 0.027 0.041 - Suzuki and Sone (unpublished)

- - - 0.00072 0.00082 - Suzuki and Sone (unpublished) - -~-- ~~ ~--- --- ---- ----- -- --- - ~--

Note: Two or three figures in one co1wnn for the same country mean the results obtained in different localities.

,