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Malaria

Malaria. Tintinalli’s Chap. 148. In General…. It is a protozoan disease caused by the bite of the Anopheles mosquito. Four species of the Plasmodium genus infect humans.(P.Vivax, P.Ovale, P.Malariae, P.Falciparum)

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Malaria

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  1. Malaria Tintinalli’s Chap. 148

  2. In General… • It is a protozoan disease caused by the bite of the Anopheles mosquito. • Four species of the Plasmodium genus infect humans.(P.Vivax, P.Ovale, P.Malariae, P.Falciparum) • P.Falciparum is the most deadly, and is becoming increasingly resistant to antimalarial medications.

  3. In General… • Transmission occurs in greater portions of Central and South America, the Caribbean, sub Saharan Africa, the Indian subcontinent, Southeast Asia, the Middle East, and Oceania. • Any patient returning from the tropics with an unexplained fever should be suspected.

  4. Pathophysiology: • The anopheline (female) mosquito bites releasing sporozoites into the host’s blood which are carried to liver. • Asexual reproduction begins in hepatic parenchymal cells, and they rupture. • Merozoites (daughters) are released and invade erythrocytes.

  5. Pathophysiology: • They mature in the erythrocytes into trophozoites and schizonts until the cell lyses and the cycle continues. • Several cycles later, the merozoites develop into sexual gametocytes which later develop into sporozoites which can infect another host.

  6. Pathophysiology: • P. Falciparum, P.Vivax, P.Ovale, and P.Malariae differ in…(see table 148-2) • Incubation period • Reproduction time • RBC preference • Morphologic features

  7. Pathophysiology: • The asexual intraerythrocytic parasite causes the symptoms and pathophysiologic consequences. • It can be transmitted by direct transfusion of infected blood or transplacentally from mother to fetus.

  8. Clinical Features: • Prodrome of malaise, myalgia, headache, low grade fevers, and chills • Some may have cough, chest pain, abdominal pain, arthralgia or diarrhea. • Eventually, the patient may have severe chills, high grade fevers, tachycardia, nausea, orthostatic dizziness, and weakness.

  9. Physical Exam: • Pts appear acutely ill with high fevers, tachycardia & tachypnea • Splenomegaly • Tender abdomen • Liver enlargement • Lymphadenopathy • Maculopapular rash

  10. Labs: • Normochromic normocytic anemia (hemolysis) • Normal or mildly depressed leukocyte count • Thrombocytopenia • Elevated ESR • Elevated LDH • Liver and renal function abnormalities • Hyponatremia, hypoglycemia • False pos. VDRL

  11. Complications: • Splenic enlargement, or rupture • Autoimmune glomerulonephritis • Cerebral malaria • Respiratory failure • Lactic acidosis • Profound hypoglycemia

  12. Diagnosis: • Giemsa stained thick and thin blood smears to view parasites • At certain stages of the infection the parasites may be undetectable. • If suspicious of malaria, failure to see the parasites on the stain is not a reason to not treat.

  13. Diagnosis: • To exclude malaria completely, repeated smears should be done twice daily for two to three days. • To determine prognosis: look for degree of parasitemia and whether P. Falciparum is present.

  14. P. Falciparum: • Look for small ring forms with double chromatin knobs within erythrocyte, and crescent shaped gametocyte. • This should be managed in a hospital setting.

  15. Treatment: • Most cases can be handled in an ambulatory setting. • Those that should be hospitalized include: those infected with P.Falciparum, infants, pregnant women, those with significant chronic medical problems.

  16. Treatment: • Uncomplicated infection with P.Vivax, P.Ovale, P.Malariae and Chloroquine sensitive P.Falciparum: • Chloroquine phosphate plus Primaquine phosphate • See Table 148-4 for dosing schedules

  17. Treatment: • Uncomplicated infection with chloroquine resistant P.Falciparum: • Quinine sulfate plus doxycycline plus or minus Pyrimethamine Sulfadoxine • Or, Mefloquine plus doxycycline or Atovaquone-Proguanil

  18. Treatment: • Complicated infection with chloroquine resistant P.Falciparum: • Quinidine Gluconate plus Doxycycline • See table 148-5 for side affects of meds • Parasite should decrease within 24-48hrs. • No asexual forms should be detected 3-4 days after treatment. • Gametocytes may persistent, but do not mean treatment failure.

  19. Treatment: • Clinical relapses usually occur unless Primaquine is used. • Primaquine should not be given to those that are glucose-6-phosphate dehydrogenase deficient. • Primaquine is not needed with P.Falciparum due to the absence of dormant asexual forms in the liver.

  20. Prevention: • Anti-mosquito measures • Antimalarial drugs • Pyrethrum containing insect spray • Insect repellent containing DEET • Appropriate chemoprophylaxis (see table 148-6) • Malaria vaccines are still in trials

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