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Travel Medicine & Insect-borne Illness for Emergency Physicians

Learn about travel medicine, specifically insect-borne illnesses, for emergency physicians. Topics include Aedes aegypti and Triatoma spp., common diseases, clinical presentations, diagnostic criteria, treatment, prevention, and the history of yellow fever.

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Travel Medicine & Insect-borne Illness for Emergency Physicians

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  1. Travel Medicine & Insect-borne Illness for Emergency Physicians Aedes aegypti Triatoma spp. Joe Alcock MD MS, NM VAMC, UNM Dept EM

  2. A bit about travel medicine • Of 100,000 travelers to the developing world in 1 month: • 300 will require hospitalization • 50 will need air evacuation • 1 will die

  3. Traveler’s Mortality • Cardiovascular 49% • Accidental Injury 22% • Infectious Disease 1% • So don’t smoke & do wear your seat belts!

  4. Spring break in Mexico Surfer returns from trip to Mexico, 3 days later - fever 104, retro-orbital headache • Doesn’t want to move • Persistent nausea & vomiting

  5. Exam shows erythematous macular rash that soon becomes confluent.

  6. Dengue (Breakbone) fever • Flavivirus • Single-stranded RNA • Widespread in tropics • 50-100 mil cases/yr • 250-500K hemorrhagic • 24K deaths

  7. Aedes aegypti • Patas blancas • Day biter • Restless feeder • Multiple hosts • Anthrophilic • 2/3 world population • Between 30°N & 20°S

  8. Mosquito Vector • Eradication: discontinued or ineffective • Transovarial spread in mosquitos • Periodically amplified in humans • Flying squirrel reservoir.

  9. Dengue increasing Vectorlikes small collections H2O Habitat for larvae Insecticide Resistance Increasing population Urbanization Common febrile disease in travelers Fl. Dept Health

  10. Variable clinical picture • Incubation is 4-7 d • Viremia 2-12 d • Petechial hemorrhage • Effusions • Vasculitis sm.Vessels • Midzonal hepatic necrosis Photo:Doug Valentine

  11. Classic Dengue • Older kids and adults • Sudden onset fever • Headache, myalgias, arthralgias of shoulders and knees • Prostrating weakness • By 3rd day: rash over thorax, flexure joints • Hyperethesia, taste aberration • Defervescence

  12. Dengue may mimic URI • 8 yo boy in Bankok develops mild fever, cough, ST, rash. Misses 1 day of school, returns the next day with no further symptoms and lifelong immunity. • In Thailand only 13% miss school in <15 yo group • Bangkok ~100% adult seroprevalence • > 15 yrs - classic dengue

  13. San Salvador, El Salvador • Female, 11, falls ill with fever, rash, myalgias, vomiting. 4 days into illness fever begins to decrease. • Confusion/somnolence. • Hct 38, then 45, then 50. • Edema, ascites, RUQ pain • B/P 70/34, requires IVF • CXR: large effusions, breathing is labored, post-intubation coma briefly precedes death.

  14. Dengue Hemorrhagic Fever • Rare • Typically afflicts patients < 15 years. • Often no hemorrhage • Diagnostic criteria include: • Platelets <100K • Evidence of capillary leak, e.g. elevated HCT, ascites of effusions, hypoproteinemia • Hemorrhagic manifestations/petechiae

  15. Tourniquet Test • Checks for hemorrhagic manifestations • Inflate blood pressure cuff to median B/P for 5 min or until petechiae are seen: > 3/sq cm

  16. Supportive No ASA/NSAIDs Treat vascular leak with IVF Massive plasma leak may last 48h Correct coagulopathy Death or complete recovery Lab diagnosis has limited clinical utility Elisa tests now available Treatment

  17. Dengue Prevention • No record of epidemic dengue 1946 and 1963 • DDT • Yellow fever • Successful in Argentina, Belize, Bolivia, Brazil, Chile, Colombia, C.R., Equador, Guatemala, Mex, Panama, Uruguay • Discontinued in 1970s

  18. Aedes aegypti • Persisted in Caribbean Islands, Venezuela, and USA. (!) • Reinfested countries where once eradicated • Dengue outbreak in Jamaica 1977, followed by epidemics until 1981 in every Caribbean island, Central and South America.

  19. Experimental Vaccine • Development started in 1970s and 1980s at Walter Reed lab • All 4 dengue serotypes • Live attenuated virus • Incomplete immunity may allow DHF if reexposed Meanwhile:

  20. Yellow fever • Flavivirus carried by Aedes aegypti • 200,000 cases/ yr • 30,000 of these die • YF in 33 countries 468 million people at risk

  21. Yellow Fever • Virus - influenza-like illness to severe hepatitis • Case fatality rate > 20%. Children, infants at risk • Risk illness & death 10 x lower in SA vs Africa

  22. FULMINANT LIVER FAILURE • Cytoplamic coagulation in hepatocytes • Councilman bodies.

  23. Yellow fever endemic areas

  24. Yellow Fever History • New World via Africa in 1600s. • Wiped out Carib tribes • 1647 Outbreaks in Mexico, Havana, Barbados, Guadeloupe • 1649 Spanish Florida • New Orleans became YF capital of Americas (with Havana)

  25. Yellow Fever • Maritime trade brings YF to NYC, Boston, Halifax • Summer 1793 Philadelphia, city of 50K. YF kills 10% of population. • City paralyzed, survivors abandon sick and dying.

  26. Yellow Fever in Travelers • Epidemic disease • 10 cases since 1979 • 4 of 5 First world cases 1996-2002 visited South America, All fatal • Risk to unvaccinated person in endemic area is 1:1000 per month • Risk to US travellers = 0.4 -4 in million

  27. Yellow Fever Vaccine • Live attenuated virus. • Contraindicated in immunosuppressed and children less than 4 years • Recommended for travel to Amazonian region and parts of Panama. Also equatorial Africa • Highly immunogenic/effective. • O.5 ml primary and 0.5ml 10 year boosters

  28. YF Vaccine Risks • Yellow Fever Vaccine-associated viscerotropic disease • Clinically & Pathologically = Yellow Fever • 23 cases of vaccine disease, 14 fatal, 17% had had thymectomy for thymoma • Elderly at risk

  29. Malaria, by contrast Briefly: • No Vaccine • Malaria kills 1,500,000 yearly • Young children and pregnant women • Immunity partial and not durable • 30,000 travelers: preventable with chemoprophylaxis and behavior

  30. Expedition to Amazonia While napping in a remote outpost, this pair wakes up to find pale fleshy bugs on their faces

  31. Kissing Bug • Barbeiro • Vinchuca • Reduviidae Triatoma spp.

  32. Chagas disease

  33. Chagas Disease Carlos Chagas, Brazilian, described the disease in 1909 He discovered the vector: Triatoma bug He named the pathogen, Trypanosoma cruzi, after his mentor, Oswaldo Cruz. Carlos Chagas Oswaldo Cruz Triatoma

  34. Chagas is endemic from Mexico to Argentina • Transmitted by Triatoma bug - 30 species are vectors. • 9 of these vectors are in the US

  35. Amazingly the bite is painless!

  36. Chagas • 16 million infected in Americas • 50,000 deaths per year • Indolent infections • Manifestations after years • Cannot be treated once chronic • Chagas results when parasite-laden feces of bug are rubbed into eye/cut

  37. Food-borne Chagas? • Sugar cane juice banned in Brazil • Guarapa • 25 confirmed cases in Santa Catarina BR • 3 deaths • Symptoms arose within days - virulent NY Times April 12, 2005

  38. Romana’s sign • Hemilateral swelling of face, eyelid, and lymphadenopathy • Acute Chagas disease in a Brazilian patient

  39. American Trypanosomiasis • Parasitemia - C-shaped trypomastigotes of T. cruzi are seen in the peripheral blood “Mal de Chagas”

  40. African Trypanosomiasis • Related trypanosome responsible for African Sleeping Sickness • T. gambiense T. rhodesiense • Tsetse fly vector • Larger than T. cruzi

  41. Chagas Disease Amastigote T. cruzi • Intracellular • Non-flagellated form • Indistinguishable from Leishmania • Giemsa stain

  42. Chagas in Tennessee • In 1998,mother of 18 month infant found triatoma bug in crib. Gut contents found to contain Trypanosoma cruzi • Infant blood was PCR positive for T. cruzi • 2 of 3 raccoons trapped in area tested positive for T. cruzi Herwaldt B.L., et al. (2000) 1998. The Journal of Infectious Diseases181: 395-399.

  43. Chagas in America • Animal reservior, T. cruzi, and Triatoma bugs are all abundant • Local transmission epidemiology unknown • 3 cases of acute Chagas disease have been recorded in US • Exact number endemic cases unknown • Many more cases are imported

  44. Chagas Heart Patients Chagas Heart Syndrome Ventricular Tachycardia, Syncope/Sudden Death, Anginal Chest Pain, Symptomatic AV block, Congestive Heart Failure. EKG suggestive of ischemia CAD mimic, underdiagnosed in US LV aneurysm, regional hypokinesis, many require pacers Hagar J.M. & Rahimtoola S.H. (1991) Chagas' heart disease in the United States. N. Engl. J. Med.325: 763-768

  45. T. Cruzi myocarditis • Amastigote in cardiomyocyte • Chronic Chagas Cardiopathy

  46. Autopsy of Bolivian Chagas Case • Infected cell in center • Diffuse lymphocytic infiltration

  47. Cardiomyopathy

  48. Chagas in US • Chronic Chagas Disease reported in Mississippi • Seropositivity in US approximately 350,000 with 100,000 cases of chronic disease • Megaesophagus, cardiomyopathy common Holbert R.D., et al. (1995) J. Miss. State Med. Assoc.36: 1-5.

  49. Mega GI manifestations

  50. Megacolon in Chagas in Bolivia • May also affect ureter, bronchus, esophagus, uterus

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