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Travel Medicine & Insect-borne Illness

Learn about common travel infections, Dengue fever, Dengue Hemorrhagic Fever, treatment, prevention, and Yellow fever vaccination risks. Stay informed to enhance your travel health safety.

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Travel Medicine & Insect-borne Illness

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  1. Travel Medicine & Insect-borne Illness Bonaire May 2007 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. Common Travel Infections • Salmonella • Shigella • Giardiasis • Amoebiasis • Hepatitis • Gonorrhea • Malaria • Helminth Infestations

  5. Complaints of Returned Travelers • GI Illness 10% • Skin lesions 8% • Respiratory 5-13% • Fever 3% • Non-tropical = majority of fevers • Tropical fever = Malaria Source: CDC Yellow Book - www.cdc.gov/travel/yb/index.htm

  6. 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

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

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

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

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

  11. Classic Dengue • Older kids and adults • Sudden onset fever • Headache, myalgias, arthralgias of shoulders and knees • Prostating 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. • 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; >20% fatality rate • Children, infants at risk • Worse in Africa • Flu-like to fulminant hepatitis

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

  22. Yellow fever endemic areas

  23. Yellow Fever • New World via Africa in 1600s. Wiped out Carib tribes • 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.

  24. 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 travelers = 0.4 -4 in million

  25. 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

  26. 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

  27. Malaria, by contrast • No Vaccine • Malaria kills 1,500,000 yearly • Young children and pregnant women • Immunity partial and not durable • 30,000 travelers: preventable illness • 400 million cases worldwide

  28. Malaria Case • January 2006, a US family w/ 5 kids visit Nigeria • Pre-trip: pediatrician gives prn meds only • No chemoprophylaxis • 3 kids all given Fansidar after fever during trip. • Kids felt better

  29. 3 had return of fever in US • Diagnosed with flu • Given antibiotics at the local clinic • Then they got sicker • Mom notices 1 child is very weak and has yellow eyes!

  30. Yellow Kid • Conjunctivae icteric • Acidosis • Hypoglycemia • 1 in 20 rbcs parasitized • Intubated • Transfused • All 5 kids tested pos for falciparum malaria

  31. Malaria Vector & Pathogen • Female Anopheles - Crepuscular hours. • Congenital and transfusion - related cases • Autochthonous: single mosquito transmits disease from 1 human to another

  32. Malaria Parasite • Major international public health problem • Charles Laveran, a French army surgeon in Algeria, recognized parasites in the blood of a malaria patient in 1880. • Nobel Prize in 1907.

  33. Role of Mosquitos • 1897, Ronald Ross, a Brit in the Indian Medical Service, discovered that mosquitos transmit malaria. • For his discovery, Ross was awarded the Nobel Prize in 1902.

  34. Major Public Health Problem • Variable risk – regional • Caused by 4 protozoan species • Plasmodium falciparum • P. Vivax • P. ovale • P. malariae

  35. Risk to travelers • Subsaharan Africa most falciparum cases • 500K US travelers to Africa vs. 21 million to other malarious areas. • Most malaria in SA and Asia is P. vivax • Relative Risk to unprotected travelers: Sub-Saharan Africa -1:50 India - 1:250 S.E. Asia-1:1,000 South America - 1:2,500 Central America -1:10,000

  36. Incubation • Following the infective bite: incubation period varies from 7 to 30 days • shorter with P. falciparum and longer with P. malariae. • Prophylaxis delays symptoms by months, after travelers leave endemic areas. • P. vivax and P. ovale: dormant liver stage parasites; may reactivate and cause disease

  37. Presenting symptoms • Fever • Chills • Sweats • Headaches • Nausea and vomiting • Body aches • General malaise.

  38. Exam findings • Fever • Sweating • Weakness • Enlarged spleen. • In P. falciparum malaria: • Mild jaundice • Enlargement of the liver • Increased respiratory rate.

  39. Severe Malaria • Cerebral malaria, AMS seizures, coma • Severe anemia, hemolysis • Hemoglobinuria • Pulmonary edema (ARDS), may occur even after treatment • Thrombocytopenia • Cardiovascular collapse and shock

  40. Warning Signs • Acute kidney failure • Hyperparasitemia, > 5% rbcs infected by parasites • Metabolic acidosis • Hypoglycemia (low blood glucose), may also occur in pregnant women with uncomplicated malaria, or after treatment with quinine.

  41. Malaria Pathogenesis • Malaria parasites digest RBC proteins and use glucose to lactic acid as energy, thus hypoglycemia & acidosis. • Injure RBC membrane: hemolysis, splenic clearance & anemia. • Makes blood cells sticky - obstruct microcirculation • Thrombocytopenia - splenic sequestration

  42. Treatment • Chloroquine • Atovoquone/ Proguanil (Malarone) • Quinine Sulfate and Doxycycline • Mefloquine side effects • Combination therapy with Artemesinin • P. vivax and malariae mostly chloroquine sensitive

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

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