Mosquito-borne Diseases of concern for Florida Citizens. Summer Roxanne Connelly, PhD. State Extension Medical Entomology Specialist

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1 Msquit-brne Diseases f cncern fr Flrida Citizens Summer 2010 By Rxanne Cnnelly, PhD State Extensin Medical Entmlgy Specialist University f Flrida Institute f Fd & Agricultural Sciences Flrida Medical Entmlgy Labratry th Street SE Ver Beach, FL crr@ufl.edu Prepared fr faculty and staff f the Flrida Cperative Extensin System

2 This dcument is prvided as a reminder f the msquit-brne diseases f cncern in Flrida, recmmendatins fr Flrida citizens t prtect themselves frm infectins frm msquites, and resurces t btain additinal infrmatin. While msquit-brne diseases are always a cncern in Flrida, there was a very lw level f msquit-brne disease transmissin t humans frm The summer f 2010 was an active msquit-brne disease seasn in Flrida. The tw issues that made this seasn different were: 1) While there are imprted cases f Dengue reprted frm Flrida travelers each year, fr the first time since 1934, there were lcally acquired cases f Dengue in the Flrida Keys; and 2) Fur cases f eastern equine encephalitis have been diagnsed in Flrida citizens. All fur f these cases resulted in fatalities. The number f eastern equine encephalitis cases in humans ver a year perid in Flrida typically des nt exceed five. Late in 2009, cases f dengue were reprted frm the Old Twn area f Key West, FL. Infectins due t dengue virus (DENV) were acquired by bites frm lcal msquites, nt frm utside f the state. Cases f dengue are still being reprted frm Old Twn. The fur human cases f eastern equine encephalitis resulting in fatalities ccurred in Hillsbrugh Cunty (2), Len Cunty (1), and Wakulla Cunty (1). Tw ther msquit-brne viruses, St. Luis encephalitis virus (SLEV) and West Nile virus (WNV) ccur in Flrida, althugh n human cases were reprted in 2010 as f August 9. The University f Flrida s Flrida Medical Entmlgy Labratry lcated in Ver Beach, FL, maintains an active surveillance prgram fr EEEV, SLEV, and WNV and releases updated risk assessments when the data warrants. The latest update can be viewed at It is my intent that this dcument will prvide yu with infrmatin yu can use when talking t news reprters, writing yur newsletters, and prviding prgrams fr the public. If yu need additinal assistance, please cntact me. Sincerely, Rxanne Cnnelly, PhD Assciate Prfessr, State Extensin Medical Entmlgy Specialist 2

3 Table f Cntents Synpsis Dengue Eastern Equine Encephalitis St. Luis Encephalitis West Nile Fever/West Nile Encephalitis Prtectin frm Msquit Bites Resurces Infrmatin cntained in this dcument is frm the University f Flrida s Flrida Medical Entmlgy Labratry and the U.S. Centers fr Disease Cntrl and Preventin. 3

4 Synpsis Each f the msquit-brne diseases described here are caused by viruses that are passed either frm msquit t human t msquit (DENV), r frm bird t msquit t human (EEEV, SLEV, and WNV). There are n vaccines available t the public r cures fr humans fr any f these 4 msquit-brne diseases. Reducing msquit larval habitats is always imprtant. Hwever, this technique by itself will nt prvide prtectin frm msquit bites. The best methd f prtectin frm msquit bites is the crrect use f effective repellents. The general descriptin fr symptms that may be present due t infectin with these msquit-brne viruses is ften simply flu-like symptms. Hwever, this descriptin des nt cnvey the severity f symptms that may accmpany infectin; that infrmatin is prvided in a detailed list f symptms fr each disease prvided in this dcument. Infected individuals respnd differently t the presence f pathgens in the human bdy, therefre, infectin with the DENV, EEEV, SLEV, r WNV may r may nt cause disease in humans. The msquit-brne diseases described here cannt be self-diagnsed, and physicians wh suspect a patient has ne f these diseases must send bld r spinal fluid samples t the state lab fr testing fr cnfirmed diagnsis. 4 Reservir Hst (is nt harmed by the virus) Flrida Vectr Species DENV Msquites Aedes aegypti Aedes albpictus EEEV Birds Cquillettidia perturbans Aedes infirmatus Culex nigripalpus Susceptible Hsts (may becme ill frm infectin with the virus) Humans Humans, hrses, extic birds Peak transmissin N/A July - August SLEV Birds Culex nigripalpus Humans August - Octber WNV Birds Culex nigripalpus Humans, hrses, crvid birds August - Octber

5 Dengue Dengue, als knwn as breakbne fever, is caused by a virus that cycles frm msquit t human t msquit. Prir t the 1940s, there were regular ccurrences f dengue utbreaks in Flrida. Since the 1940s, cases that are reprted in Flrida have been in peple wh were bitten by infected msquites while visiting dengue-endemic areas. In 2009 and 2010, lcally acquired cases f dengue were reprted frm the Flrida Keys. The msquit species respnsible fr dengue virus transmissin in Flrida are cntainer msquites because they lay their eggs in water-hlding cntainers such as thse that can be fund arund the yard and hme. The adult msquites d nt fly far frm the larval habitat and prefer t btain bld fr egg develpment n humans. The mst imprtant means f reducing risk fr cntact with dengue vectrs is by wearing effective msquit repellents and ridding the yard and hme f water-hlding cntainers that can supprt the grwth f msquit larvae. Symptms High fever and at least tw f the fllwing t indicate the disease withut labratry diagnses: Severe headache Severe eye pain (behind eyes) Jint pain Muscle and/r bne pain Rash Mild bleeding manifestatin (e.g., nse r gum bleed, petechiae, r easy bruising) Lw white cell cunt Watch fr warning signs as temperature declines 3 t 7 days after symptms began. G IMMEDIATELY t an emergency rm r the clsest health care prvider if any f the fllwing warning signs appear: Severe abdminal pain r persistent vmiting Red spts r patches n the skin Bleeding frm nse r gums Vmiting bld Black, tarry stls (feces, excrement) Drwsiness r irritability Pale, cld, r clammy skin Difficulty breathing 5

6 Distributin & Seasnality As f 31 July 2010, lcal dengue transmissin was restricted t the Old Twn area f Key West, in Mnre Cunty. Cases were reprted in the Fall f 2009 and the Spring and Summer f As f August 2010 there was nt enugh data t determine a seasnal pattern f transmissin fr dengue in Flrida. Flrida Vectrs f DENV Species Larval Habitat Distributin in Flrida Scientific name: Aedes aegypti Cmmn name: Yellw Fever Msquit Water-hlding bjects fund arund the hme and yard such as flwer vases, tires, tys, bttles, cnch shells, cans, refrigeratr drain pans, barrels, brmeliad plants, and mre. Fund in all Flrida cunties, but is nly abundant in the Flrida Keys Adults Scientific name: Aedes albpictus Cmmn name: Asian tiger msquit Water-hlding bjects fund arund the hme and yard such as flwer vases, tires, tys, bttles, cans, barrels, tree-hles, brmeliad plants, and mre. Fund in all Flrida cunties, but des nt ccur in the Flrida Keys. Abundant thrughut the state. The adults d nt fly far frm their larval habitat, generally nt mre than 500 meters. The adults d nt fly far frm their larval habitat, generally nt mre than 500 meters. DENGUE 6

7 At-risk Peple wh reside in areas where DENV is circulating in the msquit ppulatin risk expsure t infected msquites by spending time utdrs withut wearing insect repellents. Unlike many ther msquit species that are active mstly at dawn and dusk, the msquites that transmit DENV, Aedes aegypti and Ae. albpictus, are active human biters thrughut the day. Thse at a higher risk f expsure live in hmes where the windws and drs stay pen, and where screens are in disrepair. Residents r visitrs wh spend time in pen-air establishments als are at risk fr encuntering infected msquites. As f early August 2010, the nly area f Flrida where there was evidence f DENV circulatin was in the Old Twn area f Key West. Histrical fr Flrida The last epidemic f lcally-transmitted DENV in Flrida was in when an estimated 15,000 peple were reprted t be infected. Flrida 2010 Situatin (as f 31 July 2010) In 2010, 24 cases f dengue were acquired in Key West, invlving 18 residents, 5 residents f ther cunties, and ne ut-f-state visitr. Ntes: There is n specific medicatin fr treatment f a DENV infectin. Recmmendatins frm the U.S. Centers fr Disease Cntrl and Preventin fr persns wh think they have been infected are t use analgesics (pain relievers) with acetaminphen and avid medicatins cntaining ibuprfen, Naprxen, aspirin r aspirin cntaining drugs. They shuld als rest, drink plenty f fluids t prevent dehydratin, avid msquit bites while febrile and cnsult a physician. 7 DENGUE

8 Eastern Equine Encephalitis Eastern equine encephalitis has likely been present in the U.S. fr a lng time, but it wasn t until 1933 during an utbreak in hrses in the Mid-Atlantic States that it was named. This disease is rare in humans and is caused by infectin with the eastern equine encephalitis virus (EEEV) that is transmitted t humans thrugh the bite f infected msquites. Hrses infected with EEEV have a very small chance f surviving and mst ften are euthanized. Hwever, there is an effective vaccine fr hrses. The fatality rate in humans infected with the EEEV is high with nearly a 35% fatality rate, and survivrs will need medical care fr the remainder f their life. Symptms (prgressing frm nset thrugh all ptential symptms). Sudden nset f headache High Fever Chills Vmiting Disrientatin Seizures, cma Death Infected humans will respnd differently and may nt exhibit all f these manifestatins. Abut 5% f humans infected with EEEV will develp encephalitis. Distributin & Seasnality Cases have been reprted mainly frm Gulf Cast and Atlantic States and the Great Lakes regin. In Flrida, cases are spradic and tend nt t ccur in clusters. Fr example, 5 cases in 2005 ccurred in 5 different cunties. 8 EEE

9 Flrida Vectrs f EEEV Species Scientific name: Cquillettidia perturbans Larval Habitat Shallw lakes and pnds with emergent vegetatin and marshy brders; larvae and pupae attach t emergent aquatic plants, primarily cattails Distribu tin in Flrida Fund in all Flrida cunties Adult Image Scientific name: Aedes infirmatus Temprary wdland pls Fund in all Flrida cunties Scientific name: Culex salinarius Fresh r ful water f pnds, ditches, grassy pls, brackish water swamps Fund in all Flrida cunties 9

10 Cases At-risk Anyne expsed t msquites when they are biting, and when virus is circulating in a given area, are at risk f encuntering a msquit infected with EEEV. Humans invlved in the fllwing activities are at a higher risk simply due t their activity cinciding with msquit habitats at times when msquites are seeking bld fr reprductin: Wrk utside. Live, wrk, r visit areas near wdland habitats, especially thse with freshwater swamps. Participate in utdr recreatin. While the chances f being infected are high fr the at-risk activities mentined abve, peple ver 50 and under 15 years f age are at greatest risk fr experiencing severe symptms and disease. It is thught that infectin with EEEV prvides life-lng immunity frm subsequent infectin with this virus. Histrical fr Flrida: The majrity f cases are reprted during the summer mnths peaking in July Highest number f cases in a ne year perid is 5 (2005) Human EEEV Cases in Flrida as f 31 July Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nv Dec Mnth f Infectin 10 EEE

11 Flrida 2010 Situatin (31 July 2010) 4 human deaths Hillsbrugh Cunty (2), Len Cunty (1), and Wakulla Cunty (1) 11 EEE

12 Ntes: Humans and hrses are cnsidered dead-end hsts because they develp a lw amunt f virus in their bld that makes it difficult fr them t infect biting msquites. Sme birds are reservirs f the virus and are nt harmed by the presence f the virus in their bld. Hwever, extic birds such as emus and striches are highly susceptible and the virus can wipe ut entire flcks f these extic animals. 12 EEE

13 St. Luis Encephalitis St. Luis encephalitis is caused by infectin with St. Luis encephalitis virus (SLEV) transmitted t humans thrugh the bite n an infected msquit. Majr epidemics f SLEV ccurred in Flrida in 1959, 1961, 1962, 1977, and Epidemics in Flrida are cyclic, ccurring apprximately every years, but the virus is cnsidered t be endemic in this area. Hrses are nt affected by SLEV. Symptms Fever Headache Dizziness Nausea Malaise Less than 1% f SLEV infectins will develp int clinical illness. Severe infectins prgress t: Stiff neck Cnfusin Disrientatin Dizziness Tremrs Unsteadiness Cma Abut 40% f children and yung adults infected with SLEV develp nly fever and headache r aseptic meningitis; almst 90% f elderly persns with SLEV develp encephalitis. The verall case-fatality rati is 5 t 15%. The risk f fatal disease als increases with age. 13

14 Distributin St. Luis Encephalitis Cases Reprted by State, SLE

15 Flrida Vectrs f SLEV Species Larval Habitat Distributin in Flrida Scientific name: Culex quinquefasciatus Cmmn name: Suthern Huse Msquit Highly rganic, plluted, ful water in cntainers, catch basins, grund pls, effluent frm sewage treatment areas, abandned swimming pls, dairy lagns, ditches, animal watering tanks. Fund in all Flrida cunties Adults Scientific name: Culex nigripalpus Ditches, cntainers, grassy pls, dairy lagns, furrws f citrus grves Fund in all Flrida cunties, abundant thrughut the state. At-risk The Flrida vectrs f SLEV are mst active in seeking bld meals frm dawn t dusk. Anyne bitten by a msquit in an area where the virus is circulating can get infected with SLEV. The risk is highest fr persns wh engage in utdr wrk and recreatinal activities and thse living in lw-incme areas. Elderly persns are at increased risk f severe disease if they are infected. 15 SLE SLE

16 Histrical fr Flrida Flrida 2010 Situatin (31 July 2010) There was n evidence f SLEV activity in Flrida. Ntes: The larval habitats f msquit species invlved in transmissin f SLEV in Flrida are nt usually assciated with cntainers arund the hme. The larval habitats ccur n a much larger scale, such as pastures, rchards, waste water sites, etc., and are best managed by rganized msquit cntrl districts. The best methd against infectin with SLEV is thrugh the use f effective insect repellents. 16 SLE

17 West Nile Fever/West Nile Encephalitis West Nile virus (WNV) was detected in the United States in 1999 in New Yrk and by 2001 was reprted in Flrida. Human infectins ccur thrugh the bite f an infected msquit. Human and animal (hrse) cases f West Nile increased frm , but then tapered ff t abut 3 human and 3 hrse cases per year. The majrity f human and hrse cases in Flrida ccur in late summer thrugh early fall. There is a vaccine t prevent WNV in hrses, but there is n vaccine fr humans. Symptms West Nile Fever Fever Headache Bdy aches Nausea Vmiting Swllen lymph glands Skin rash n chest, stmach and back West Nile Encephalitis High fever Headache Neck stiffness Stupr Disrientatin Cma Tremrs Cnvulsins Muscle weakness Visin lss Numbness Paralysis Abut ne in 150 peple infected with WNV will develp severe illness. The symptms may last several weeks, and neurlgical effects may be permanent. Up t 20 percent f the peple wh becme infected have mild symptms that can last fr as shrt as a few days, thugh even healthy peple have becme sick fr several weeks. Apprximately 80 percent f peple (abut 4 ut f 5) wh are infected with WNV will nt shw any symptms at all. 17 WN

18 Distributin & Seasnality 18 WN

19 Cases Flrida Vectrs f WNV Species Larval Habitat Distributin in Flrida Scientific name: Culex nigripalpus Ditches, cntainers, grassy pls, dairy lagns, furrws f citrus grves Fund in all Flrida cunties, abundant thrughut the state. Adults At-risk Spending time spent utdrs increases the risk fr a persn t be bitten by an infected msquit. Pay attentin t aviding msquit bites if yu spend a lt f time utside, either wrking r playing. Peple ver the age f 50 are mre likely t develp serius symptms frm infectin with WNV if they d get sick and shuld take special care t avid msquit bites. Age is by far the mst imprtant risk factr fr develping neurinvasive WNV infectin. All dnated bld is checked fr WNV befre being used. The risk f getting WNV thrugh bld transfusins and rgan transplants is very small, and shuld nt prevent peple wh need surgery frm having it. If yu have cncerns, talk t yur dctr. Pregnancy and nursing d nt increase the risk f becming infected with WNV. The risk that WNV may present t a fetus r an infant infected thrugh breast milk is still being evaluated. Talk with yur care prvider if yu have cncerns. Histrical fr Flrida 100 Human Cases f West Nile in Flrida as f 31 July Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nv Dec Mnth f Infectin 19 WN

20 Flrida 2010 Situatin (July 31, 2010) Tw WNV-psitive hrses were reprted: Oscela (1); Jeffersn (1) 20 WN

21 Prtectin frm Msquit Bites The U.S. Centers fr Disease Cntrl and Preventin (CDC) recmmends the use f prducts cntaining active ingredients which have been registered by the U.S. Envirnmental Prtectin Agency (EPA) fr use as repellents applied t skin and clthing. EPA registratin f repellent active ingredients indicates the materials have been reviewed and apprved fr efficacy and human safety when applied accrding t the instructins n the label. CDC evaluatin f infrmatin cntained in peer-reviewed scientific literature and data available frm EPA has identified several EPA registered prducts that prvide repellent activity sufficient t help peple avid the bites f disease carrying msquites. Prducts cntaining these active ingredients typically prvide reasnably lng-lasting prtectin: Efficacy f repellents varies amng individuals and is affected by: Temperature Perspiratin Humidity Activity level Expsure t water Msquit species Other factrs DEET (Chemical Name: N,N-diethyl-m-tluamide r N,N-diethly-3-methyl-benzamide) Picaridin (KBR 3023, Chemical Name: 2-(2- hydrxyethyl)-1-piperidinecarbxylic acid 1- methylprpyl ester ) Oil f Lemn Eucalyptus* r PMD (Chemical Name: para-menthane-3,8-dil) the synthesized versin f il f lemn eucalyptus IR3535 (Chemical Name: 3-[N-Butyl-N-acetyl]- aminprpinic acid, ethyl ester) In general, higher cncentratins f active ingredient prvide lnger duratin f prtectin, regardless f the active ingredient, althugh cncentratins abve ~50% d nt ffer a marked increase in prtectin time. Prducts with <10% active ingredient may ffer nly limited prtectin, ften frm 1-2 hurs. Prducts that ffer sustained release r cntrlled release (micr-encapsulated) frmulatins, even with lwer active ingredient cncentratins, may prvide lnger prtectin times. Regardless f what prduct yu use, if yu start t get msquit bites reapply the repellent accrding t the label instructins r remve yurself frm the area with biting insects if pssible. * Nte: This recmmendatin refers t EPA-registered repellent prducts cntaining the active ingredient il f lemn eucalyptus (r PMD). Pure il f lemn eucalyptus (e.g. essential il) has nt received similar, validated testing fr safety and efficacy, is nt registered with EPA as an insect repellent, and is nt cvered by this CDC recmmendatin. 21

22 Repellents fr use n clthing: Certain prducts cntaining permethrin are recmmended fr use n clthing, shes, bed nets, and camping gear, and are registered with EPA fr this use. Permethrin is highly effective as an insecticide and as a repellent. Permethrin-treated clthing repels and kills ticks, msquites, and ther arthrpds and retains this effect after repeated laundering. The permethrin insecticide shuld be reapplied fllwing the label instructins. Sme cmmercial prducts are available pretreated with permethrin. EPA recmmends the fllwing precautins when using insect repellents: Apply repellents nly t expsed skin and/r clthing (as directed n the prduct label.) D nt use repellents under clthing. Never use repellents ver cuts, wunds r irritated skin. D nt apply t eyes r muth, and apply sparingly arund ears. When using sprays, d nt spray directly n face spray n hands first and then apply t face. D nt allw children t handle the prduct. When using n children, apply t yur wn hands first and then use the material n yur hands t apply it t the child. Yu may nt want t apply materials t children s hands t avid the chance they culd transfer the materials t the eyes and muth. Use just enugh repellent t cver expsed skin and/r clthing. Heavy applicatin and saturatin are generally unnecessary fr effectiveness. If biting insects d nt respnd t a thin film f repellent, then apply a bit mre. After returning indrs, wash treated skin with sap and water. This is particularly imprtant when repellents are used repeatedly during the day r n cnsecutive days. Als, wash treated clthing befre wearing it again. (This precautin may vary with different repellents check the prduct label.) If yu r yur child gets a rash r ther reactin frm an insect repellent, stp using the repellent, wash the repellent ff with mild sap and water, and call a lcal pisn cntrl center fr further guidance. If yu g t a dctr because f the repellent, take the repellent with yu t shw the dctr. Nte that the label fr prducts cntaining il f lemn eucalyptus specifies that they shuld nt t be used n children under the age f three years. Other than thse listed abve, EPA des nt recmmend any additinal precautins fr using registered repellents n children r n pregnant r lactating wmen. 22

23 Fr additinal infrmatin regarding the use f repellent n children, please see CDC s Frequently Asked Questins abut Repellent Use. [ The University f Flrida s Flrida Medical Entmlgy Labratry has tested and published the results n the efficacy f the fllwing repellents. Average Cmplete Prtectin Time is the time that elapses between the prper applicatin f a repellent until the first msquit lands n the prtected area. Prducts Active Ingredient Average Cmplete Prtectin Time OFF! Deep Wds 23.8% DEET 5 hurs Sawyer Cntrlled Release 20% DEET 4 hurs OFF! Skintastic 6.65% DEET 2 hurs Repel Lemn Eucalyptus Insect Repellent Oil f lemn eucalyptus; p-menthane 3,8-dil (PMD) 2 hurs Bite Blcker fr Kids 2% Sybean Oil 1.5 hurs OFF! Skintastic fr Kids 4.75% DEET 1.5 hurs Skin-S-Sft Bug Guard 7.5% IR minutes Plus Natrapel 10% Citrnella 20 minutes Herbal Armr 12% Citrnella; 2.5% peppermint il; 2% cedar il; 1% lemngrass il; 0.05% geranium il 19 minutes Green Ban fr Peple 10% Citrnella; 2% peppermint il 14 minutes Buzz Away 5% Citrnella 14 minutes Skin-S-Sft Bug Guard 0.1% Citrnella 10 minutes Skin-S-Sft Bath Oil Active Ingredient nt knwn 10 minutes Skin-S-Sft Misturizing 0.05% Citrnella 3 minutes Suncare Gne Original Wristband 9.5% DEET 0 Repell Wristband 9.5% DEET 0 Gne Plus Repelling 25% Citrnella 0 Wristband 23

24 Resurces EDIS Fact Sheets Dengue Eastern equine encephalitis Msquit Repellents West Nile Virus Msquit Infrmatin Website Encephalitis Infrmatin System (Available in English and Spanish) Flrida Msquit Cntrl Assciatin American Msquit Cntrl Assciatin Arbviral Epidemic Risk fr Flrida Link t websites fr Flrida Msquit Cntrl Prgrams (by cunty) 24