arbovirus epidemiology

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Arbovirus Epidemiology

2

nd

Quarter DIDE TrainingMay 18, 2011

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Obe!tives

• Des!ribe t"e epidemiology o# endemi! arboviral

in#e!tions a##e!ting "umans in t"e $nited %tates

• &rie#ly revie' ot"er arboviral diseases t"at maybe reported #ollo'ing travel outside t"e $nited

%tates

• Dis!uss mos(uito bite prevention

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Arboviruses

• Art"ropod)borne virus

– *iruses maintained in nature t"roug" biologi!al

transmission bet'een sus!eptible vertebrate "osts by

blood #eeding art"ropods +mostly mos(uitoes

– Over 1-0 arboviruses .no'n to !ause disease in "umans

– T"ree virus #amilies/• Togaviridae

• laviviridae

•

&unyaviridae

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Arbovirus Transmission

• Transmission intensity !oin!ides 'it" a!tivity o# ve!tor – ate spring t"roug" early #all +#or mos(uitoes – In!ubation period/ usually - to 18 days

• umans are dead)end "osts +i3e3, do not be!omeviremi! – T"ere are e4!eptions

• &lood trans#usions•

Organ transplants• 5erinatal e4posure• 6ertain viruses +e3g3, !"i.ungunya virus, dengue,

et!3

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uman Arboviral In#e!tions

• 6lini!al spe!trum varies 'idely – Most in#e!tions are asymptomati! – 6an range #rom mild #ever to asepti! meningitis or

en!ep"alitis

• 7on)neuroinvasive vs3 neuroinvasive

• %ymptomati! in#e!tions !an result in !ompli!ations – ospitaliation, long)term neurologi! dys#un!tion,

or even deat"

• *a!!ines, spe!i#i! treatment generally not available #ormost arboviruses

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Maor Arboviruses Endemi! in $3%3

• 9estern e(uine en!ep"alitis virus +9EE

• Eastern e(uine en!ep"alitis virus +EEE

• %t3 ouis en!ep"alitis virus +%E

• 5o'assan virus +5O9

• 9est 7ile virus +97*

• 6ali#ornia %erogroup viruses

– a 6rosse en!ep"alitis virus +A6

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9EE

• amily/ Togaviridae +genus/ Alphavirus

– irst isolated in 1:-0 +"orse, 6ali#ornia

•7o "uman !ases in $3%3 #or past 10 years – Maority o# !ases 'est o# Mississippi ;iver

– *e!tor and virus still persist in a##e!ted region

• ;is. groups/

– rural residents o# t"e 9est +parti!ularly!"ildren <1 year

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9EE 7euroinvasive Disease 6ases

;eported by %tate, 1:=>?200:

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EEE

• amily/ Togaviridae +genus/ Alphavirus – irst isolated in 1:-- +"orse, *irginia

•

Average o# = !ases reported per year +range/ 0?20 – Atlanti! and @ul# !oastal areas, @reat a.es

• ;is. groups – 5ersons B0 years or <1B years are "ig"est

ris. – -0C o# en!ep"aliti! !ases result in deat"

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EEE 7euroinvasive Disease 6ases ;eported

by ear, 1:=>?200:

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EEE 7euroinvasive Disease 6ases ;eported

by %tate, 1:=>?200:

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%E

• amily/ laviviridae +genus/ Flavivirus

– irst isolated in 1:-- +"uman, Missouri

•Average o# 102 !ases reported per year +range/ 2?1,:=

– ;eported t"roug"out $3%3

– Outbrea.s/ Mississippi *alley and @ul# 6oast

• ig" ris.

– Elderly, lo' in!ome

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%E 7euroinvasive Disease 6ases

;eported by ear, 1:=>?200:

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%E 7euroinvasive Disease

6ases ;eported by %tate, 1:=>?200:

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5O9


– irst isolated in 1:B8 +"uman, 6anada

– Transmitted by a ti!. +primarily Ixodes cookei

• Average o# - !ases reported per year +range/ 0?

– Most !ases in 7e' England, $pper Mid'est

• ig" ris.

– Adults t"at spend time in ti!. "abitats

– 10?1BC result in deat"

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5O9 7euroinvasive Disease

6ases ;eported by %tate, 2001?200:

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97*


– irst isolated in 1:- +"uman, $ganda

•Average o# 2,B00 !ases reported per year +range/21?:,8=1

– Emerged in 1:::, (ui!.ly pea.ed in 200-

– %pread t"roug"out !ontinental $3%3

• ig" ris.

– 5ersons B0 yrs o# age

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97* 1:::

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97* 2000

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97* 2001

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97* 2002

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97* 200-

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97* 2010

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A6

• amily/ &unyaviridae +genus/ Bunyavirus, 6ali#ornia – irst isolated in 1:=> +"uman, 9is!onsin – 7early all 6ali#ornia serogroup viruses are due to

A6

• Average o# 8 !ases reported per year +range/ 2:?1= – Most !ases o!!ur in $pper Mid'estern, mid)

Atlanti! and sout"eastern states

• ig" ris./ – 6"ildren <1= years

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6ali#ornia %erogroup *irus 7euroinvasive

Disease 6ases ;eported by %tate, 1:=>?200:

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Cluster

(2003–2007)*

Median

Inciden

ce

RR

#1 (Nicholas,Fayette,

Raleigh)

110 per100,000

(15years)

9!2

#2 ("yoi$g,%c&o'ell,%ercer)

40 per100,000(15

years)

4!3

a**o' +&, i-ler &, +*oi, +! .hespatial epi*eiology a$* cli$ical/eatres o/ reporte* cases o/ a rosseirs i$/ectio$ i$ "est irgi$ia /ro2003 to 2007! BMC Infectious Diseases

2011, 1129



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Ot"er Arboviruses ) Dengue

• 1F- o# t"e global

population lives in

endemi! !ountries

–9O estimates upto 100 million

!asesFyear

– 20,000 deat"s

+mostly !"ildren

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Dengue in t"e $nited %tates

• >-= travel)asso!iated !ases reported in $3%3

in 2010 +most #rom 5;

• Outbrea. in a'aii in 2001?2002

• o!al transmission reported in lorida

beginning 200: +B- !ases in 2010

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Ot"er Arboviruses ) 6IG

• 6"i.ungunya

– Transmission do!umented in - !ountries

• 5rimarily #ound in A#ri!a and Asia

•

13> million !ases reported in 200= – Travel)asso!iated !ases do!umented in $3%3

• 10: !ases sin!e 1::B

– %imilarities 'it" dengue

• %ame ve!tors• umans !an be!ome reservoirs '"en

in#e!ted

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6"allenges

• Outbrea.s – In#re(uent – $npredi!table

• @eograp"i! distribution .no'ledge

• %urveillan!e

• 5reventionF!ontrol

• Treatment

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&e a'are o# pea. mos(uito "ourso or many mos(uitoes, pea. "ours are bet'een dus.

and da'n or evening and early morning3o or t"e mos(uitoes t"at transmits a 6rosse

en!ep"alitis virus pea. "ours are a!tually during t"edaytime +da'n until dus.3

$se inse!t repellant t"at !ontains DEET, pi!aridin,I;-B-B or oil o# lemon eu!alyptus on e4posed s.inand !lot"ing '"en outdoors3o Al'ays #ollo' pa!.age dire!tions3o Apply sparingly to !"ildren, avoiding "ands and #a!e,

and 'as" t"em 'it" soap and 'ater '"en t"ey !omeindoors3

o 5ermet"rin is a repellant t"at !an be applied to !lot"ingand provide prote!tion t"roug" multiple 'as"es3 Donot apply permet"rin)!ontaining repellants dire!tly tos.in3



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%ummary

• Arboviral in#e!tions result #rom virusesmaintained in nature bet'een art"ropods andvertebrate "osts

• A6 !ontinues to be t"e primary arbovirus o#"uman !on!ern in 9*

– Ot"er arboviruses may result #rom out)o#)stateor international travel

• 5revention e##orts !enter around removal o#breeding sites and repellant use

arbovirus epidemiology

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