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ACHA 2009

ACHA 2009. Name That Bug. Malaria-A Major World Disease. 300-500 million cases annually 2.7 million deaths annually About 1500 US cases annually Prevalence increasing Rising resistance Anopheles vector spreading Climate change Increasing travel. Malaria.

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ACHA 2009

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  1. ACHA 2009 Name That Bug

  2. Malaria-A Major World Disease • 300-500 million cases annually • 2.7 million deaths annually • About 1500 US cases annually • Prevalence increasing • Rising resistance • Anopheles vector spreading • Climate change • Increasing travel

  3. Malaria • A major cause of fever in the returning traveler • A complicated disease • But resources are available

  4. Fever in the Returning Traveler • The Geosentinel Study • Malaria is #1 • Then Dengue • Mononucleosis • Rickettsial infection • Enteric fever (Typhoid or paratyphoid fever)

  5. Malaria Etiology • Caused by Plasmodium, a parasite • Four important species • P. falciparum • P. vivax • P. ovale • P. malariae

  6. The four species are not the same • Falciparum • Often severe • High parasite burden • Organ damage common • Non-falciparum • Generally not severe • Low parasite burden • Rare end organ damage

  7. Malaria Transmission • Predominantly due to the bite of a female Anopheles mosquito • In US, there is rare transfusion spread • Also some “airport” infection

  8. Malaria Pathogenesis • The parasite digests red blood cell proteins, hemoglobin and deform the cell membrane • Hemolysis occurs • Cytokines released • Diseased cells filtered out by spleen and liver • Results in sequestration and enlargement

  9. Malaria Signs and Symptoms • Fever • Sweats • Chills • Headache • Myalgias • Fatigue • Abdominal pain

  10. Malaria Diagnosis • Light microscopy • Look at blood with Giemsa stain (or Wright’s stain) • Look for ring forms in red cells, measure percent of red cells infected, look for “banana” forms

  11. This is not vivax

  12. CDC Assistance • Call 770 488 7788 during normal business hours • Call 770 488 7100 for emergencies

  13. Next Case

  14. The Salmonellae • Motile gram negative bacilli • Some cause gastroenteritis • Some cause enteric fever • Some cause bacteremia or endovascular infection • Some cause osteomyelitis or abscess • Some cause asymptomatic carrier state

  15. This case was an example of enteric fever • Typhoid • Salmonella typhi • Salmonella paratyphi • Both are highly specific for human, not animal, infection • Always means that there was contact with an infected individual, a chronic carrier or contaminated food or water • 21.6 million cases worldwide in one year, with 216,000 deaths

  16. Typhoid in the USA • Between 1994-1999 there were 1393 cases • 30% had traveled to India • Strongly consider the typhoid vaccine

  17. The Clinical Picture of Typhoid • A febrile illness • Occurs 5-21 days after ingestion of the bacteria • Fever builds, is often sustained • May have abdominal pain, rose spots, liver or spleen enlargement • If untreated, has 15% mortality • Other symptoms may include headache, cough, relative bradycardia

  18. The Diagnosis • Established by blood culture

  19. Sensitivity to Antibiotics • Cipro often considered first choice • But beware: resistance is growing • Lab testing may miss Cipro resistance, so specifically ask about sensitivity to nalidixic acid

  20. Cipro

  21. Next Case

  22. Tuberculosis • Koch’s disease • Received the Nobel prize for establishing that TB was caused by Mycobacteria tuberculosis in 1882

  23. Tuberculosis • A disease of antiquity • Mummies have had TB • A disease of poverty • A large fraction of cases in US are imported • An indolent infection • A disease of the “artiste” • For example the opera La Boheme

  24. TB Epidemiology • 14.6 million cases of active TB worldwide each year • 1.6 million deaths per year • 25,000 new US cases per year • About 50% are in foreign born

  25. TB Presentation • Symptoms are insidious • Fever present in 50% • Cough, weight loss or fatigue present in 66% • X-ray often shows upper lobe infiltrate

  26. A Critical Lab Test for Suspected Active Disease • Collect multiple sputum specimens for “AFB smear and culture with sensitivity” • New tests are emerging to aid in diagnosis

  27. TB Transmission and Prevention • Generally by inhalation of droplet particles • One sneeze can create 40,000 droplets • Screening high prevalence populations is helpful

  28. TB Screening • Focus is to detect both active disease and latent disease • ACHA has guidelines • Traditional test for latent TB is the Tuberculin skin test • Newer tests utilize interferon assay • These tests are now recognized by CDC as equivalent to skin testing

  29. TB Screening Tests • Skin Testing • An acquired skill • Requires two visits • Well established • Much data on sensitivity • Cost stable • BCG may cause false positive • Interferon Tests • Only needs phlebotomy skills and lab • One visit for result • Cost high, but coming down • Not prone to BCG influence Less data on sensitivity

  30. TB Treatment • Needs multiple effective drugs for long period of time • ATS has established guidelines

  31. Next Case

  32. Fish Tapeworm Infection • Diphyllobothrium Latum, the broad tapeworm • Endemic wherever raw or undercooked fish is ingested • Full grown worm lives in the human intestine, may reach 40 feet in length, may cause vitamin B12 deficiency with megaloblastic anemia

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