Malaria Obstacles and Opportunities (1991) / Chapter Skim
Currently Skimming:
Pages 22-36
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 22... ...
2Background MALARIA AS A DISEASE Malaria in humans is caused by four species of protozoan parasites of the genus Plasmodium: P falciparum, P
|
From page 23... ...
duration of exposure to infective mosquitoes may also influence the severity of the disease. Clinical Aspects The clinical manifestations of malaria are varied.
|
From page 24... ...
Malaria during pregnancy can cause miscarriages, fetal death, intrauterine growth retardation, low birth weight, and premature delivery. Women pregnant for the first time and in their third trimester are at particular risk for severe anemia and sometimes even death.
|
From page 25... ...
disappear from the peripheral blood during schizogony, few or no parasites may be present in a blood smear; examination of blood smears taken at frequent intervals may be necessary to establish a diagnosis. A positive blood smear taken from a feverish patient living in an endemic region does not conclusively implicate malaria as the cause of illness, because many asymptomatic individuals have circulating parasites in their blood and the fever may be due to other infectious agents.
|
From page 26... ...
is transmitted to humans by the sporozoite forms in the saliva of infected female mosquitoes of the genus Anopheles. Soon after entering the human host, the sporozoites invade liver cells, where during the next 5 to 15 days they develop into schizonts.
|
From page 27... ...
into a schizont containing 8 to 32 new merozoites. The red blood cell eventually ruptures and releases the merozoites, which are then free to invade additional red blood cells.
|
From page 28... ...
may deposit a total of 200 to 1,000 eggs in three or more batches. Actual egg production is dependent on blood consumption.
|
From page 29... ...
Mosquitoes seek their host in response to a combination of chemical and physical stimuli, including carbon dioxide plumes, certain body odors, warmth, and movement. Anopheline Mosquitoes feed most frequently at night and occasionally in the evening, or in heavily shaded or dark areas during the early morning.
|
From page 30... ...
THE ENVIRONMENT Environmental conditions help determine the intensity of malaria transmission. The optimal climate for sporogony, or parasite development in the mosquito, is a temperature of between 20¹C and 30¹C with humidity in excess of 60 percent.
|
From page 31... ...
Fi gu re 2 -6 E pi de m io lo gi ca l a ss es sm en t o f t he st at us o f m al ar ia , 1 98 9.
|
From page 32... ...
regions of the world. Plasmodium falciparum, the most clinically dangerous of the malaria parasites, is the most widespread in Africa south of the Sahara and throughout the world's tropics.
|
From page 33... ...
Transmission Epidemiologists have devised a number of ways of classifying the type of malaria transmission in a particular area. Two of the most common are based on levels of endemicity and stability.
|
From page 34... ...
and adults suffer severe disease. In meso- and hypoendemic regions, the frequency of infection is generally low, but epidemics may be devastating.
|
From page 35... ...
concerns about the use and efficacy of other available antimalarial drugs. Chloroquine-resistant P
|
From page 36... ...
Vaccines Much recent research has focused on developing effective malaria vaccines (see Chapter 9)
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.