diphyllobothrium: homegrown or a foreign traveller

DIPHYLLOBOTHRIUM- HOMEGROWN OR FOREIGN

TRAVELLOR

A LABTECH PRESENTATIONBy Tom Henderson

Consists of at least 13 species all of which can infect humans.

Two intermediate hosts copepods of several types fish both fresh and marine Many definitive hosts carniverous animals such as bears and

dogs. Also fish eating birds

DIPHYLLOBOTHRIUM SP.


Humans are also included amongst the definitive hosts.

Cases are increasing in recent years due to more consumption of raw fish and importation of raw fish from endemic areas

Conservative estimate is 20 million cases world-wide


Incubation period in humans is typically 4-6 weeks but varies from 2 weeks to 2 years.

Proglottids wider than longer may grow 1cm/hr with tapeworm reaching 25 metres (typically 2-15 metres).

One to several segments detach regularly releasing immature eggs

DIPHYLLOBOTHRIUM SP

Interventions include prevention of water contamination ie defecating in streams and lakes by infected locals or tourists.

Effective screening of infected people. Proper handling of raw, undercooked or marinated

fish. Must be cooked, brined or frozen (48hrs at -18c)


Presents with diarrhoea, abdo pain, vomiting, weight loss, fatigue, constipation and discomfort.

Severe cases may have vit B12 deficiency and Megaloblastic anaemia.

Large worm burdens lead to bowel obstruction. 80% of cases may remain undetected.


Ova are operculate and measure 58-75 x 40-50


Treatment options include Praziquantel 5-10mg/kg side effects are few Niclosamide 50mg/kg side effects are nil

CASE-12002 - 29 MALE

Worked as a tour guide in Alaska where he had eaten raw Salmon.

Proglottids measured 8mm wide by 5mm long. Ova were within the expected size range and were

operculated with an abopercular thickening.

CASE-12002

CASE-22009-52 MALE

Previous infestation of tapeworm. Tx in Jan with Praziquantel and in Dec with

Mebendazole. Proglottids measured 8mm wide by 4mm long. Ova were within the expected range and were typical

of Diphyllobothrium sp.

CASE-22009

CASE-32011-58 FEMALE

Recent change in bowel motions, constipation then loose motions. ?tapeworm passed.

No history of overseas travel other than Australia. Ate partly raw trout in new zealand (central otago)

and raw salmon in Akaroa.

CASE-3

Proglottids measured 4mm wide by 3mm long. Ova were typical in size to the other cases and were

operculated with an abopercular thickening.

CASE-3

COMPARISON

COMPARISON

It appears that each of these tapeworms are different species especially that from case-3.

Also the case history does not readily support a conventional acquisition of Diphyllobothrium.

The possibility exists that case-3 represents a New Zealand infection.

SUMMARY

Three cases of infection due to Diphyllobothryiasis are presented.

Each tapeworm however appears different although broadly falls within the criteria of being wider than longer.

Since asymptomatic infections are more common it is possible that further cases are present within the N.Z. population.

SUMMARY

It is possible that an indigenous fish tapeworm could be present within New Zealands waters either in Salmonid fish or Indigenous perch which are notable vectors in Europe.

Current tapeworms are being analysed for DNA identification by Trevor and by Histology experts in Australia.

AFTERMATH

Attempts at DNA extraction have proved unsuccessful due to preservation in formalin.

Literature records a Japanese patient with Diphyllobothryiasis upon return from NZ

Studies in Australia have recorded dogs and other small animals with various species of Diphyllobothrium sp.

THE MESSAGE

New Zealanders are at risk from acquiring tapeworm infestation including

Fasciola hepatica ( liver fluke ) Hymenolepsis nana ( rat tapeworm ) Diphyllobothrium sp. ( fish tapeworm) An ova concentration is an important part of any

parasite investigation

THE MESSAGE

Changes in food habits to include ever more varied and “wild” options increase our exposure to intestinal parasites.

Global warming can allow the spread of intermediate hosts and consequently the spread of intestinal pathogens.

diphyllobothrium: homegrown or a foreign traveller

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