6. Multiple Plasmodium falciparum infections in Tanzanian infants

Felger, Ingrid; Smith, T.; Edoh, Dominic; Kitua, Andrew Y; Alonso, Pedro L.; Tanner, Marcel; Beck, Hans‐Peter

doi:10.1016/s0035-9203(99)90324-3

Cited by 53 publications

(54 citation statements)

References 21 publications

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“…Finally, it might be expected that the reduction in parasite density would lead to reduced multiplicity, since multiplicity of infection in this study population is positively correlated with parasite density (Felger et al 1999b). However, we found no differences in the proportion or mean number of MSP-2 genotypes between infants with normal haemoglobin and those heterozygous for the sickle cell trait.…”

Section: Discussionmentioning

confidence: 81%

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Malaria infection and morbidity in infants in relation to genetic polymorphisms in Tanzania

Stirnadel

Stöckle

Felger

et al. 1999

Tropical Med Int Health

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SummaryTo investigate the effects of host polymorphisms on malaria morbidity and infection, the frequency distributions of TNF ␣ promotor gene and sickle cell trait were studied in infants in an area highly endemic for Plasmodium falciparum transmission in Tanzania. Differences in parasite prevalence, density, febrile episodes with and without parasitaemia, PCV levels and the frequencies of different MSP-2 parasite infections were assessed by genotype. The frequency of the TNF ␣ promotor allele 2 was 0.09, and the trait was in Hardy-Weinberg equilibrium. There were no differences in malariametric indices between infants with the normal TNF ␣ promoter gene and those who were heterozygous for this trait. Infants heterozygous for the TNF ␣ promotor gene appeared to have fewer febrile episodes when they were free of parasites. The two infants homozygous for the TNF ␣ promoter allele 2 had both a much higher incidence of fever, independently of parasitaemia, than the average for the other genotypes. The frequency of the sickle cell allele S was 0.06 and the trait was also in Hardy-Weinberg equilibrium. Infants heterozygous for the sickle cell trait had significantly lower parasite densities, but similar prevalence, and MSP-2 infections compared to infants with normal haemoglobin. PCV levels, and the incidence of febrile episodes both with and without parasitaemia were also similar. In contrast to the sickle cell trait, the TNF ␣ promotor polymorphism appeared not to have any protective effect on malaria in this study, and its importance in other unspecified fever-causing diseases in this population needs further investigation.keywords Plasmodium falciparum malaria, tumour necrosis factor-␣ promotor polymorphism, sickle-cell trait, infants correspondence Heide A. Stirnadel,

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Section: Discussionmentioning

confidence: 81%

“…For this analysis, infections were categorized into the two allelic families, namely FC27 and 3D7. The distribution and mean number of concurrent infections of MSP-2 in infants is described elsewhere in detail (Felger et al 1999b).…”

Section: Assessment Of Multiple Parasite Infectionsmentioning

confidence: 99%

Malaria infection and morbidity in infants in relation to genetic polymorphisms in Tanzania

Stirnadel

Stöckle

Felger

et al. 1999

Tropical Med Int Health

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“…In infants, MOI is strongly associated with parasite density and malarial disease. 6,10,33 After birth and a short period of relative protection, infants are successively exposed to a broad range of parasite strains, only few of which are likely to be recognized by strain-specific or crossreactive immune mechanisms. 4,11 With age many individuals develop a repertoire of immune responses and are able to control an increasing number of different P. falciparum strains.…”

Section: Discussionmentioning

confidence: 99%

“…This is in accordance with the observation that after an age of approximately two years children infected with multiple strains are less likely to subsequently experience clinical attacks. 5,6,33 In successive pregnancies, women are also more likely to be repeatedly exposed to more and more strains and to develop strain-specific and cross-reactive immunity.…”

Section: Discussionmentioning

confidence: 99%

Multiplicity of Plasmodium falciparum infection in pregnancy.

Beck¹,

Mockenhaupt²,

Bienzle³

et al. 2001

The American Journal of Tropical Medicine and Hygiene

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Abstract. Little is known about the distribution and disease association of multiple Plasmodium falciparum infections in pregnant women. Genotyping of the merozoite surface protein-1 region was performed in 332 P. falciparum infected pregnant women in Ghana, and clinical and epidemiologic data were obtained. Overall, 68% of the women were infected with more than one strain (mean number of strains per carrier ϭ 2.9). The multiplicity of infection decreased significantly with an increasing number of pregnancies, and infection with multiple P. falciparum strains was significantly associated with anemia. In logistic regression, women infected with four or more strains were 2.3 times more likely to be anemic than women harboring fewer strains. This association, however, was only observed in women with up to three pregnancies. The results suggest that with increasing gravidity and subsequent infections with multiple strains effective immune mechanisms against more and more strains develop. In pregnant women, the multiplicity of infection may be an important factor for the acquisition and maintenance of immunity against malaria.

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“…A mean of five concurrent infections was found in children from highly endemic settings in Africa (22,23), whereas in Papua New Guinea (PNG), the reported MOI ranged from 1.7 to 1.9 (24,25). In children less than 3 y old, each additional infecting clone was associated with a higher prospective risk, whereas for older children it appeared that multiple infections protect against clinical attacks (22,(26)(27)(28).…”

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confidence: 99%

Force of infection is key to understanding the epidemiology ofPlasmodium falciparummalaria in Papua New Guinean children

Müeller

Schoepflin

Smith

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

117

154

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Genotyping Plasmodium falciparum parasites in longitudinal studies provides a robust approach to estimating force of infection (FOI) in the presence of superinfections. The molecular parameter mol FOI, defined as the number of new P. falciparum clones acquired over time, describes basic malaria epidemiology and is suitable for measuring outcomes of interventions. This study was designed to test whether mol FOI influenced the risk of clinical malaria episodes and how far mol FOI reflected environmental determinants of transmission, such as seasonality and small-scale geographical variation or effects of insecticide-treated nets (ITNs). Two hundred sixty-four children 1-3 y of age from Papua New Guinea were followed over 16 mo. Individual parasite clones were tracked longitudinally by genotyping. On average, children acquired 5.9 (SD 9.6) new P. falciparum infections per child per y. mol FOI showed a pronounced seasonality, was strongly reduced in children using ITNs (incidence rate ratio, 0.49; 95% confidence interval, [0.38, 0.61]), increased with age, and significantly varied within villages (P = 0.001). The acquisition of new parasite clones was the major factor determining the risk of clinical illness (incidence rate ratio, 2.12; 95% confidence interval, [1.93, 2.31]). Adjusting for individual differences in mol FOI completely explained spatial variation, age trends, and the effect of ITN use. This study highlights the suitability of mol FOI as a measure of individual exposure and its central role in malaria epidemiology. It has substantial advantages over entomological measures in studies of transmission patterns, and could be used in analyses of host variation in susceptibility, in field efficacy trials of novel interventions or vaccines, and for evaluating intervention effects.infection dynamics | cohort studies | molecular monitoring

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6. Multiple Plasmodium falciparum infections in Tanzanian infants

Cited by 53 publications

References 21 publications

Malaria infection and morbidity in infants in relation to genetic polymorphisms in Tanzania

Malaria infection and morbidity in infants in relation to genetic polymorphisms in Tanzania

Multiplicity of Plasmodium falciparum infection in pregnancy.

Force of infection is key to understanding the epidemiology ofPlasmodium falciparummalaria in Papua New Guinean children

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