FALCIPARUM MALARIA*
Section snippets
EPIDEMIOLOGY
About 40% of the world's population is at risk for acquiring malaria, resulting in 300 to 500 million cases yearly.119 About 80% of these occur in subsaharan Africa, where malaria mortality is more than 1 million deaths annually, killing 1 out of 20 children in rural Africa before they reach 5 years of age. Outside of Africa, malaria causes about 100,000 deaths yearly. Vigorous efforts to eradicate malaria occurred in the 1950s and 1960s, but many of these have been abandoned. Few experts now
BIOLOGY
Falciparum is one of four species of Plasmodium causing human infection, all transmitted by mosquitoes of the genus Anopheles.79 Characteristics of anophelines relevant to the clinician are as follows:
Feed from dusk to dawn
Rest with bodies pointed up at angle to wall
Only females feed on vertebrates, blood needed for egg production
Must survive long enough (9–22 days) after feeding to transmit infection—dependent on temperature, humidity, predators (bats, birds), insecticides
Species-related
PATHOPHYSIOLOGY
P. falciparum has several features that make it the deadliest of malarias. Its capacity for amplification is greatest because red blood cells of any age can be invaded, allowing parasitemias to reach 30%. Most insidious is the parasite's ability to sequester in the capillaries and postcapillary venules of vital organs such as the brain and kidney. Only the first half (24 hours) of each erthrocytic cycle is seen in the peripheral blood. During the second half of the cycle, the more mature forms
DIAGNOSIS
Most important in diagnosing malaria are considering the disease in the first place, taking a thorough travel history, appreciating the nonspecific presentation of the illness, making and studying blood smears, and recognizing severe or complicated malaria. Malaria cannot be accurately diagnosed by history and clinical exam. The only reliable symptom is fever, so malaria must be considered in any patient with fever after a visit to a malarious locale.
General Principles
The ideal antimalarial drug reduces parasitemia quickly and persists long enough to eliminate all parasites. To achieve this, drugs must rapidly reach effective blood levels and interdict the erythrocytic cycle so that no new schizonts can be produced. Some drugs, such as quinine, quinidine, and artemisinin, rapidly reach effective concentrations but have short half-lives. The parasite burden in falciparum malaria may approach 1012, so that even with 4 log killing (99.99%) per cycle, it would
PREVENTION
Countries with malaria transmission are listed in Table 5.16 Within ew2ach country, variations in risk exist because of altitude, climate, season, and degree of urbanization. Because the vector feeds mostly at night, it is important to determine where the traveler will be between dusk and dawn. Many tourists visit malarious areas only as part of daytime tours, returning to malaria-free areas to sleep.
All travelers to areas where insects are vectors of dangerous diseases need counselling to
ACKNOWLEDGMENT
The authors thank Dr. Jan Zucker, Dr. Dennis Shanks, Dr. Terrie Taylor, Dr. Malcolm Molyneux, Dr. Steve Hoffman, Dr. Larry Miller, Dr. Mark Wallace, and Dr. Peter Echeverria for advice and Mrs. Marge Knight and Mrs. Jane Dempsey for library assistance.
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Modified peptides and organic metabolites of cyanobacterial origin with antiplasmodial properties
2024, International Journal for Parasitology: Drugs and Drug ResistanceRole of chemoprophylaxis during de-induction in preventing complicated falciparum malaria
2023, Medical Journal Armed Forces IndiaPredictive factors of severe disease secondary to falciparum malaria among travelers
2011, Pathologie BiologiePlasmodium falciparum malaria occurring 8 years after leaving an endemic area
2009, Diagnostic Microbiology and Infectious DiseaseCitation Excerpt :As the patient exhibited features of severe malaria with a parasitemia of greater than 5% and the presence of acute renal failure, treatment needed to be initiated immediately. Delays in starting effective therapy for P. falciparum malaria have been associated with mortality rates exceeding 20% (Murphy and Oldfield, 1996). The treatment of malaria depends on the infecting plasmodia species and the geographic area of acquisition, which affects the likelihood of drug resistance and the severity of disease.
Specific Infections with Critical Care Implications
2008, Critical Care Medicine: Principles of Diagnosis and Management in the Adult
Address reprint requests to: Gerald S. Murphy, MD US NAMRU–2 (Jakarta) Box 3, Unit 8132 APO AP 96520–8132 (USA)
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The opinions expressed in this chapter are those of the authors and are not to be construed as representing the official policy of the U.S. Navy or the Naval Service at large.
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From the Infectious Disease Divisions, Internal Medicine Departments, Naval Medical Center San Diego, California (GSM); and Eastern Virginia Medical School, Norfolk, Virginia (ECO)