897 resultados para historical of malaria
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The rodent malaria parasite Plasmodium berghei develops in hepatocytes within 48-52h from a single sporozoite into up to 20,000 daughter parasites, so-called merozoites. The cellular and molecular details of this extensive proliferation are still largely unknown. Here we have used a transgenic, RFP-expressing P. berghei parasite line and molecular imaging techniques including intravital microscopy to decipher various aspects of parasite development within the hepatocyte. In late schizont stages, MSP1 is expressed and incorporated into the parasite plasma membrane that finally forms the membrane of developing merozoites by continuous invagination steps. We provide first evidence for activation of a verapamil-sensitive Ca(2+) channel in the plasma membrane of liver stage parasites before invagination occurs. During merozoite formation, the permeability of the parasitophorous vacuole membrane changes considerably before it finally becomes completely disrupted, releasing merozoites into the host cell cytoplasm.
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Mode of access: Internet.
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Includes index.
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Mode of access: Internet.
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Unpaged.
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Mode of access: Internet.
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Mode of access: Internet.
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Spine title: McCulloch's geographical dictionary.
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Mode of access: Internet.
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Although most of the Papua New Guinea highlands are too high for stable malaria transmission, local epidemics are a regular feature of the region. Few detailed descriptions of such epidemics are available, however. We describe the investigation of a malaria epidemic in the Obura Valley, Eastern Highlands Province, Papua New Guinea. Of the 244 samples examined by microscopy, 6.6% were positive for Plasmodium falciparum only, 9.4% were positive for Plasmodium vivax only, and 1.2% were mixed infections. MSP2 and MSP3alpha genotyping and AMA1 sequencing were used to determine the genetic variation present in a sample of P. falciparum and P. vivax infections. The P. vivax infections were found to be genetically highly diverse. In contrast, all P. falciparum samples were of a single genotype. This striking difference in genetic diversity suggests endemic, low-level local transmission for P. vivax but an outside introduction of P. falciparum as the most likely source of the epidemic.
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Malaria control strategies are more likely to be successful if groups at high risk can be accurately predicted. Given that mosquitoes have an obligate aquatic phase we were interested in determining how vector larval abundance relates to the spatial distribution of human malaria infection. We examined the relationship between malaria parasite prevalence and distance from vector larval habitat, and vector larval abundance and distance from human habitation, in separate studies in rural, low-endemic areas of the Philippines. Parasite prevalence among symptomatic patients was significantly higher among those living in proximity ( less than or equal to 50 m) to potential larval habitats of the major vector, Anopheles flavirostris (adjusted odds ratio [AOR] 2.64, P = 0.02 and AOR 3.43, P = 0.04). A larval survey of A. flavirostris revealed a higher density of early and late instars near human habitation (adjusted P < 0.05). The results suggest that larvae are associated with human habitation, thereby reinforcing malaria risk in people living close to larval habitats. This has implications for understanding the interaction between vectors, hosts, and parasites, and the potential for success of localized malaria control measures.