Vector-Borne Diseases & Identifying Other Arthropod-Related Maladies & Disorders

1. Vector-Borne Diseases & Identifying Other Arthropod-Related Maladies & Disorders Presented by Minoo Madon and Stephanie Heintz Greater LA County Vector Control District

2. Purpose • Lack of vector-borne disease training, resulting in misdiagnoses and under-reporting, • Clinicians need to be aware of symptoms • Quick and accurate reporting can result in proper treatment, thus saving lives.

3. District Overview • A local non-enterprise independent special district. • Formed in 1952 and governed by a Board of Trustees • Provide services to 34 cities within Los Angeles County and sections of unincorporated LA County. • Funded through annual benefit assessment - 2005-06 assessment =$5.29 per parcel. • Staffing: 53 full-time personnel

4. We Prevent and Control Vectors • Mosquitoes • Africanized honeybees • Black Flies • Midges *Program discontinued in July 2002

5. District Departments • Operations • Vector control efforts using physical, chemical, and biological agents • Scientific-Technical • Disease surveillance for WEE, SLE, and WNV • Community Outreach • Promotes public awareness of district services • Administrative • Maintenance

6. Arbovirus Disease Reporting Vector Control Districts Conduct disease surveillance : SLE, WEE, WNV Submit mosquito & blood samples from chickens and wild birds Report positive human cases, horses, dead birds, sentinel chickens, and mosquitoes Human cases Los Angeles County Public Health Dept. Acute Communicable Disease Control Responsible for disease reporting California Department of Health Services Samples sent to the University of Davis Arbovirus Research Unit Responsible for disease reporting

7. Disease Overview • Mosquito-Borne • Tick-Borne • Flea-Borne • Wild Rodent-Borne • Other arthropod related illnesses

8. Mosquito-Borne Diseases

9. The Mosquito Life Cycle Adult Adult 7-10 days to complete the entire life cycle Eggs Pupae Larvae

10. Mosquito Breeding Sources Discarded tires Out-of-orderfountains Out-of-order swimming pools Discarded cans and jars

11. Male vs. Female Mosquito Female Male Only females bite and transmit disease

12. Mistaken For A Mosquito ½ inch in length Over 1 inch in length or more depending on species Mosquito Crane Fly

13. Encephalitides Disease Life Cycle Virus maintenance through vertical transmission (eggs to offspring) host vector Incidental or “dead end” host Incidental or “dead end” host

14. Arboviral Encephalitides • Arbovirus: virus transmitted by arthropods • Four main virus agents in the U.S. (all mosquito-transmitted) • Eastern equine encephalitis (EEE) • Western equine encephalitis (WEE) • St. Louis encephalitis/ West Nile virus (WNv) • La Crosse encephalitis (LAC) • Powassan: northern U.S. (deer ticks) • Venezuelan equine encephalitis (VEE) in Central and South America (mosquitoes) • Japanese encephalitis widespread throughout Asia (mosquitoes)

15. Symptoms • Majority of human infections are asymptomatic • Non-specific flu-like syndrome • In general, affects the central nervous system • Sudden fever, headache, myalgias, malaise. Infection may lead to encephalitis, coma, paralysis, permanent neurologic sequelae, and death

16. Treatment • Antibiotics are not effective • No effective antiviral drugs • Treatment is supportive therapy: assist breathing, prevent bacterial pneumonia • Vaccines available for: • Japanese encephalitis (U.S.) • Tick Borne encephalitis (Europe) • Equine vaccine for EEE, WEE, VEE, WNv

17. Laboratory Diagnosis • Has changed over the last few years • Relied on four tests: • Hemagglutination-inhibition (HI) • Complement fixation (CF) • Plaque reduction neutralization test (PRNT) • Indirect fluorescent antibody (IFA) • Current tests: • IgM-capture ELISA (MAC-ELISA) • IgG ELISA

18. La Crosse Encephalitis (LAC) • Endemic to Midwestern and Mid-Atlantic states • Cycled between the tree-hole mosquito, chipmunks and tree squirrels in forest habitats • Maintained over the winter through transovarial transmission • Non-specific summertime illness • Cases occur in children under 16-years of age • Reported as aseptic meningitis or viral encephalitis of unknown etiology • No specific treatment • Less than 1% mortality rate

19. Eastern Equine Encephalitis (EEE) • Eastern seaboard, Gulf Coast, inland Midwestern locations • Transmitted to humans and equines • Involves birds and mosquitoes in swampy areas, but spreads by “bridge vectors” • Introduced by migratory birds in the spring • Summer and fall • 35% of all people with EEE will die and those who recover will suffer permanent brain damage

20. Western Equine Encephalitis (WEE) • Western U.S. (California) • Transmitted to humans and horses • Involves passerine birds and mosquitoes • Human cases of WEE are usually first seen in June or July • Most cases are asymptomatic • Children under 1 year old are affected more severely • Mortality rate is 3%

21. St. Louis Encephalitis (SLE) • Distributed throughout lower 48 states • The most common mosquito-transmitted pathogen in the U.S. • Maintained in a mosquito-bird-mosquito cycle • Summer season • Majority of infections remain undiagnosed • Adults most severely affected-milder in children • Elderly are at highest risk for severe disease • Mortality rate is 5-15%

22. West Nile Virus

23. West Nile Virus • Active in all states, except Hawaii and Alaska • Transmitted principally by Culex species, and in rare cases blood transfusions, organ transplants, and mother-to-child • Migratory birds play an important role in the natural transmission cycle and spread • Incubation period: 5-15 days (after bitten by infected mosquito)

24. WNV Human Infection “Iceberg” Inflammation of brain, spinal cord: profound muscle weakness, flaccid paralysis, seizures, and coma <1% WN Encephalitis ~20% West Nile Fever Headache, fever, muscle/body aches, joint pain, nausea, rash (occasionally) No symptoms ~80% Asymptomatic

25. WNV: Clinical Description • Severe Disease: neuroinvasive infection • West Nile meningitis: fever, headache, stiff neck • West Nile Encephalitis: most severe form with loss of consciousness, coma, limb paralysis, and tremors • West Nile poliomyelitis: flaccid paralysis syndrome is less common than meningitis and encephalitis. Involvement of respiratory muscles leading to respiratory failure

26. Diagnostic Tests for Severe Disease • Serological tests for WNv cross react with closely related flaviviruses • PRNT is the most specific test • Most infected are asymptomatic and IgM antibody may persist for 6-months or longer • Residents in endemic areas may have persistent IgM antibody from a previous infection that is unrelated • Most Efficient method: • Detection of IgM antibody to WNV serum within 8-14 days of illness • Cerebrospinal fluid collection within 8 days of illness onset using MAC-ELISA.

27. Clinical Suspicion • Seriously considered in adults over 50 years of age, especially in immunocompromised individuals who have onset of unexplained encephalitis or meningitis in late summer or fall • Neuroinvasive disease can occur in persons of all ages, year round in southern states • WNv should always be considered in persons with unexplained encephalitis and meningitis.

28. Dengue

29. History of Dengue • First reported epidemics occurred in 1779-1780 in Asia, Africa, and North America • Pandemic in Southeast Asia after WWII • Epidemics caused by multiple serotypes are more frequent. • Geographic and mosquito vector has expanded • Long intervals between epidemics (10-40 years) • Pan American Health Organization eradicated Ae. Aegypti from most Central and South American countries in the 1950’s and 60’s • Fatality rate is 5% among children and young adults

30. Dengue Fever • Four virus serotypes=4 infections during lifetime • Tropical disease maintained by Aedes aegypti and humans • Illness ranges from nonspecific viral syndrome to severe and fatal hemorrhagic disease • Risk factors: • strain and serotype • age • immune status • genetics of patient

31. Dengue Fever • Small but significant risk for dengue outbreaks in the continental United States • Two competent mosquito vectors: Ae. aegypti and albopictus. • Transmission detected in Texas (1980’s and 2005) and epidemics in northern Mexico • So. Texas and southeastern U.S. where Ae. aegypti is found, are at risk for dengue transmission and outbreaks • Rely on physicians to recognize Dengue in patients. Many cases go unreported • No vaccine is available

32. Clinical Diagnosis • Dengue • Fever, headache, myalgias, nausea, vomiting, maculopapular rash, taste sensation change • Symptoms milder in children than adults • Indistinguishable from influenza, measles, or rubella • Treatment emphasizes relief of symptoms

33. Clinical Diagnosis • Dengue Hemorrhagic Fever • Fatal form of dengue • Fever lasting 2 to 7 days. As fever subsides, patient shows signs of circulatory failure and hemorrhagic manifestations • May rapidly evolve into dengue shock syndrome (DSS) and death • DSS include abdominal pain, vomiting, fever to hypothermia, or mental status change • Effectively managed by fluid replacement and if diagnosed early, fatality rates kept below 1% • Pain/fever management: acetaminophen and not aspirin, which acts as an anticoagulant, aggravating bleeding • DHF/DSS fatality rate is 44%

34. Laboratory Diagnosis • Virus isolation • Serum specimen collected ASAP or within 5 days after onset of symptoms • Serological Diagnosis • Convalescent-phase serum specimen obtained at least 6 days after onset of symptoms is required • Tested for anti-dengue antibodies by enzyme-linked immunosorbent assay (ELISA) • These samples should be sent to the State Health Department and forwarded to the CDC for testing

35. Epidemiology • Dengue-like illness observed in a person in the continental U.S. who has recently traveled to an endemic, tropical area. • A blood specimen, clinical information, and a brief travel history should be sent to CADHS and CDC

36. Malaria

37. Malaria • In humans, caused by 4 protozoan species of the genus Plasmodium: • P. falciparum • P. vivax • P. ovale • P. malariae • World-wide, ~500 million cases annually with ~ 5 million fatalities • Transmitted by female Anopheles mosquito • Occasionally by transfusion or congenitally from mother to fetus

38. Occurrence • Transmission occurs in large areas of Central and South America, Africa, Asia (Indian subcontinent, Southeast Asia, and the Middle East), Eastern Europe, and the South Pacific • Malaria is not endemic to the United States. • Most US travelers acquire P. falciparum in sub-Saharan Africa (urban and rural areas) • Lower malaria transmission in Asia and S. America because most urban areas do not have transmission

39. Malaria Transmission Cycle

40. Clinical Presentation • Influenza-like symptoms and can occur in intervals • Associated with anemia and jaundice • P. falciparum infections can cause seizures, mental confusion, kidney failure, coma, and death • Symptoms can occur several months later • No vaccine is currently available • Prevention: Drug regimen and anti-mosquito measures • Could acquire Malaria during chemoprophylaxis use • Can be fatal if treatment is delayed

41. Tolerability • Chemoprophylaxis: (CDC recommendations) • Mefloquine or chloroquine (1-2 weeks before travel) • Doxycycline and atovaquone (1-2 days) before travel • Starting medication 3-4 weeks in advance allows potential adverse events to occur prior travel

42. Symptoms • Fever and flu-like illness: • Shaking chills • Headache • Muscle aches • Nausea, vomiting, and diarrhea • Anemia and jaundice (yellow coloring of the skin and eyes) because of the loss of red blood cells • Plasmodium falciparum, if not promptly treated, may cause kidney failure, seizures, mental confusion, coma, and death

43. Diagnosis • Symptoms begin 10 days to 4 weeks after infection, although a person may feel ill as early as 7 days or as late as 1 year later • When these parasites come out of hibernation and begin invading red blood cells (“relapse”) the person will become sick • Any traveler who becomes ill with a fever or flu-like illness while traveling and up to 1 year after returning home should immediately seek professional medical care

44. Treatment • Should be treated early in its course • Malaria can be cured with prescription drugs • Depends on which kind of malarial parasite is diagnosed • Age of the patient • Whether the patient is pregnant • How severely ill the patient is at start of treatment

45. Is it a Life-Long Disease? • Not necessarily, if the right drugs are used, people who have malaria can be cured and all the malaria parasites can be eliminated • Can persist if it is left untreated or if it is treated with the wrong drug • Some drugs are ineffective because the parasite is resistant to them. Some patients may be treated with the right drug, but at the wrong dose or for too short a period of time

46. Yellow Fever

47. Yellow Fever • Occurs only in Africa and South America • Very rare cause of illness in travelers • Most countries require a yellow fever vaccination prior to entering • The vaccine: immunity lasts 10 years • People who should NOT receive the vaccine • Infants under 6 months of age • Pregnant women • Persons hypersensitive to eggs • Persons with HIV, AIDS, or immunosuppressed

48. Tick-Borne Diseases

49. Lyme Disease (LD) • Spread by a tick bite in the genus Ixodes. In CA Ixodes pacificus (western blacklegged tick) • Forest, coastal scrub, oak woodlands & open grasslands • The ticks are infected with Borrelia burgdorferi (spirochetes) • Most cases of human illness occur in the late spring and summer when immature ticks (tiny nymphs) are most active and human outdoor activity is greatest • Lyme disease ecology: • Presence of spirochetes • Ixodes ticks • Mammals such as mice and deer

50. Ticks • Blacklegged ticks have three feeding stages: • Larvae • Nymph • Adult • Adult ticks feed on deer, and deer do not become infected. Deer are important in transporting ticks and maintaining tick populations.