Prospective risk of morbidity in relation to malaria infection in an area of high endemicity of multiple species of Plasmodium.

Smith, T.; Genton, Blaise; Baea, Kay; Gibson, N.; Narara, A.; Alpers, Michael P.

doi:10.4269/ajtmh.2001.64.262

Cited by 54 publications

(54 citation statements)

References 21 publications

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Section: Why Are P Malariae and P Ovale Infections Still Important?mentioning

confidence: 99%

“…Apart from differences in a wide range of ecological factors (such as climate and Anopheline vector species), these contrasting observations in P. malariae epidemiology could be linked to the virtual absence of Plasmodium vivax infections in many African populations because of the lack of the Duffy blood-group-antigen, which P. vivax requires to invade red blood cells [33]. Interestingly, Smith et al reported that in Wosera, PNG, P. vivax infections might be associated with an antagonistic effect on P. malariae infections [34].…”

Section: Variation In Parasite Prevalencementioning

confidence: 99%

“…This led the authors to propose that the increased susceptibility to P. malariae might partly be responsible for the mild courses of P. falciparum malaria that occur in α-thalassaemic pregnant women. Similarly, in a study in PNG, infections with P. malariae were associated with a subsequent decrease in overall health-centre attendance with presumptive malaria, with a stronger effect on non-P. falciparum rather than P. falciparum disease [34]. By contrast, observations from the Gambia showed that in children under seven years P. malariae episodes are most common in the dry season, when P. falciparum infections and illness are less common [37].…”

mentioning

confidence: 93%

“…Although cross-sectional studies have reported positive associations between infections of P. falciparum and P. malariae and/or P. ovale, respectively [3,27,28,34], these associations are more likely to represent individual differences in exposure (i.e. children with a high risk of acquiring P. falciparum infections also have a high risk of acquiring other infections) [34] or susceptibility to infection [27], rather than true biological interactions between the parasite species.Third, because P. malariae is often overlooked by LM, it is difficult to assess potential negative associations or 'suppression' by P. falciparum and/or P. vivax in mixed infections. The observed seasonal differences in Africa between P. falciparum and P. malariae prevalence rates and P malariae densities have been interpreted as a suppression of P. malariae during the periods of high P. falciparum transmission, at least in older individuals [5,8,27].…”

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confidence: 99%

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Plasmodium malariae and Plasmodium ovale – the ‘bashful’ malaria parasites

Müeller

Zimmerman

Reeder

2007

Trends in Parasitology

270

245

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Although Plasmodium malariae was first described as an infectious disease of humans by Golgi in 1886 and Plasmodium ovale identified by Stevens in 1922, there are still large gaps in our knowledge of the importance of these infections as causes of malaria in different parts of the world. They have traditionally been thought of as mild illnesses that are caused by rare and, in case of P. ovale, short-lived parasites. However, recent advances in sensitive PCR diagnosis are causing a re-evaluation of this assumption. Low-level infection seems to be common across malaria-endemic areas, often as complex mixed infections. The potential interactions of P. malariae and P. ovale with Plasmodium falciparum and Plasmodium vivax might explain some basic questions of malaria epidemiology, and understanding these interactions could have an important influence on the deployment of interventions such as malaria vaccines. Geographical distributionAlthough distribution of Plasmodium malariae infection is reported as being patchy, it has been observed in all major malaria-endemic regions of the world [1]. P. malariae infections are most common in sub-Saharan Africa and the southwest Pacific, where age-specific prevalence in mass blood surveys have exceeded 15-30% [2][3][4][5][6][7][8]. By contrast, when P. malariae has been detected in malaria-endemic regions of Asia [9][10][11][12], the Middle East [13], South America [14] and Central America [15], it is observed as an infrequent infection, with blood-smear light microscopy (LM) prevalence rarely exceeding 1-2%. Much higher levels of infection were, however, found in montagnard refugees from the Cambodian-Vietnamese border [16]. In South America, P. malariae is thought to be a zoonotic infection because the genetically identical Plasmodium brasilianum infects new-world monkeys [17] and both monkeys and humans in endemic areas show high levels of seropositivity to P. malariae and P. brasilianum antigens [18].Plasmodium ovale was thought to have a much more limited distribution, with endemic transmission traditionally described as being limited to areas of tropical Africa, New Guinea, the eastern parts of Indonesia and the Philippines [19,20]. Infections with P. ovale, however, have also been reported in the Middle East [13], the Indian subcontinent [21] and different parts of Southeast Asia [11,22,23]. In West Africa (and to a lesser extent Central Africa), age specific LM prevalence of >10% have been observed [3,6] places where P. ovale is observed, it is relatively uncommon and its prevalence (as detected by LM) rarely exceeds 3-5% [22,[24][25][26].Indepth descriptions of the epidemiology of both infections based upon LM data are, thus, restricted almost exclusively to highly endemic areas in Africa and the Southwest Pacific. Detailed epidemiological studies from South America and Asia are lacking. Variation in parasite prevalenceIn West Africa, P. malariae prevalence has been reported to peak at ages similar to those of P. falciparum (i.e. in children under ten years of...

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Section: Why Are P Malariae and P Ovale Infections Still Important?mentioning

confidence: 99%

Section: Variation In Parasite Prevalencementioning

confidence: 99%

mentioning

confidence: 93%

mentioning

confidence: 99%

See 2 more Smart Citations

Plasmodium malariae and Plasmodium ovale – the ‘bashful’ malaria parasites

Müeller

Zimmerman

Reeder

2007

Trends in Parasitology

270

245

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“…Although the overall evidence for such a cross-protective effect is inconclusive, a study in PNG has shown that a prior infection with P. vivax reduced the likelihood of a later clinical P. falciparum episode but not the risk of a P. falciparum infection. 31 Good diagnosis and prompt treatment of all malaria cases, but especially of imported P. falciparum, is the key for the prevention of future epidemics in the Obura valley. Distribution of insecticide-impregnated bed nets might support these efforts by reducing local transmission.…”

Section: Discussionmentioning

confidence: 99%

The population structure of Plasmodium falciparum and Plasmodium vivax during an epidemic of malaria in the Eastern Highlands of Papua New Guinea.

Müeller¹,

Kaiok²,

Reeder³

et al. 2002

The American Journal of Tropical Medicine and Hygiene

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Abstract. 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 MSP3␣ 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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