Dynamics of P. falciparum gametocytemia in symptomatic patients in an area of intense perennial transmission in Tanzania.

Akim, N. I. J.; Drakeley, Chris; Kingo, T.; Simon, Beatus; Senkoro, K.P.; Sauerwein, Robert W.

doi:10.4269/ajtmh.2000.63.199

Cited by 61 publications

(59 citation statements)

References 22 publications

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“…Accordingly, P. falciparum gametocyte carriage rate among the study participants with asymptomatic Plasmodium infections in the study area was high (66.7%). This was higher than the P. falciparum gametocyte carriage rates documented among asymptomatic Plasmodium-infected individuals in Ethiopia, 17 Gambia, 18 Bangladesh, 19 and Tanzania, 20 in which P. falciparum gametocyte carriage rates were 41.2% (7/17), 10.5%, 2.5%, and 30.5%, respectively. The high gametocyte prevalence observed among the study participants would suggest that asymptomatic Plasmodium-infected individuals could serve as a reservoir of infection in the study setting.…”

Section: Discussioncontrasting

confidence: 54%

High Prevalence of Gametocyte Carriage among Individuals with Asymptomatic Malaria: Implications for Sustaining Malaria Control and Elimination Efforts in Ethiopia

Degefa¹,

Zeynudin²,

Zemene³

et al. 2016

Human Parasitic Diseases

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Asymptomatic malaria often contributes to the reservoir of infection in disease transmission. This study reports the prevalence of gametocyte carriage among asymptomatic individuals and assesses the risk factors associated with asymptomatic malaria in the suburbs of Jimma town, southwestern Ethiopia. A cohort of 582 individuals residing in the suburbs of Jimma town was followed up for three months from September 2013 to November 2013. A total of 1,746 blood films were collected using active case detection. Sociodemographic profile of the study participants was collected using a pretested semistructured questionnaire. The incidence of asymptomatic Plasmodium falciparum malaria was 17.18/1,000 person-months at risk, and for Plasmodium vivax, it was 17.8/1,000 person-months at risk. The gametocyte carriage rates of P. falciparum and P. vivax were 66.7% and 12.9% among asymptomatic P. falciparum-and P. vivax-infected individuals, respectively. Geometric mean gametocyte and asexual parasite density among asymptomatic malaria cases were 412.66 (interquartile range [IQR], 300-660) and 1,866.61 (IQR, 900-6,540) parasites/μL, respectively. Age, place of residence, and distance from vector-breeding site were the main predictors of asymptomatic malaria. The high gametocyte carriage among individuals with asymptomatic malaria in the study area calls for screening and treatment of asymptomatic carriers to interrupt transmission and enhance malaria elimination efforts.

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Section: Discussioncontrasting

confidence: 54%

High Prevalence of Gametocyte Carriage among Individuals with Asymptomatic Malaria: Implications for Sustaining Malaria Control and Elimination Efforts in Ethiopia

Degefa¹,

Zeynudin²,

Zemene³

et al. 2016

Human Parasitic Diseases

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“…However, in the mouse model of competitive release and facilitation, SP treatment increased density of gametocytes as well as asexual blood stage parasites (17). In humans, increased asexual parasite density is associated with increased gametocyte density (28). The effects of IPTp to increase the fraction of highly drug-resistant variants and to increase parasite density might act in concert to accelerate the spread of resistant parasites.…”

Section: Discussionmentioning

confidence: 99%

Competitive facilitation of drug-resistant Plasmodium falciparum malaria parasites in pregnant women who receive preventive treatment

Harrington

Mutabingwa

Muehlenbachs

et al. 2009

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

188

244

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Intermittent preventive treatment in pregnancy (IPTp) is used to prevent Plasmodium falciparum malaria. However, parasites resistant to the IPTp drug sulfadoxine-pyrimethamine (SP) have emerged worldwide, and infections with mixed resistant and susceptible parasites are exacerbated by pyrimethamine in mice. In a prospective delivery cohort in Muheza, Tanzania, we examined the effects of SP IPTp on parasite resistance alleles, parasite diversity, level of parasitemia, and inflammation in the placenta. IPTp use was associated with an increased fraction of parasites carrying the resistance allele at DHPS codon 581, an increase in the level of parasitemia, and more intense placental inflammation. The lowest mean level of parasite diversity and highest mean level of parasitemia occurred in women after recent IPTp use. These findings support a model of parasite release and facilitation, whereby the most highly resistant parasites out-compete less fit parasite populations and overgrow under drug pressure. Use of partially effective anti-malarial agents for IPTp may exacerbate malaria infections in the setting of widespread drug resistance.evolution of drug resistance ͉ intermittent preventive treatment in pregnancy ͉ malaria drug resistance ͉ pregnancy malaria M alaria during pregnancy causes both maternal and fetal morbidity and mortality, including the deaths of an estimated 100,000 infants each year because of malaria-related low birth weight. The World Health Organization recommends that women living in sub-Saharan Africa receive at least two doses of intermittent preventive treatment (IPTp) with sulfadoxinepyrimethamine (SP) to prevent malaria and improve pregnancy outcomes (1-5) and this advice is widely followed. However, the rapid spread of SP-resistant parasites might undermine the efficacy of SP-IPTp, although it still confers benefits in areas with low to moderate levels of drug resistance (6). The effect of SP IPTp in areas where resistant parasites are more widespread has not been studied.Pyrimethamine and sulfadoxine target the parasite proteins DHFR and DHPS, respectively, and increasing resistance is conferred by ordered accumulating point mutations, of which DHPS codon 581 is one of the final to occur (7). The mutation at DHPS codon 581 has been associated with high-level in vitro resistance (8), as well as treatment failure in children (9, 10). Single-dose treatment of children with SP has been associated with an increase in parasite resistance alleles (11, 12), but little work has been done to examine the relationship between IPTp and selection for drug resistance alleles. One recent study observed an increased prevalence of placental infections harboring the DHFR triple mutant in women who had received pyrimethamine prophylaxis during pregnancy, as compared with women who had not (13). In contrast, IPTp use was not related to increased prevalence of resistance alleles at the same study site (14). Modeling studies have proposed that IPTp is less likely to contribute to accumulating drug resistance as...

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“…Our study is simply a contribution to this general knowledge, with particular reference to the situation in Western Kenya. Although rural health clinics in malaria-endemic areas represent excellent surveillance points for monitoring malaria infection dynamics and evaluation of the effects of malaria intervention programmes, acquirement of gametocyte-infected blood for vector competence studies requires alternative approaches such as active surveillance in the community and schools (10,20,21,37) or follow up of patients post antimalarial drug treatment (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)26,29).…”

Section: Discussionmentioning

confidence: 99%

Infectivity of <i>Plasmodium falciparum</i> gametocytes in patients attending rural health centres in western Kenya

Gouagna

Okech²,

Kabiru³

et al. 2004

E Af Med Jrnl

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Background: Experimentally studying the transmission of the malaria parasite and its regulating factors requires availability of human blood donors carrying infectious gametocytes. The difficulty of identifying gametocyte carriers from the community is often limited due to financial and human resources constraints. The available alternative is rural health centres where malaria patients go for treatment. In this study, the potential of recruiting volunteers and acquiring infectious blood for experimental infections from rural health centers in malaria endemic area was examined through routine patient diagnosis.

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Dynamics of P. falciparum gametocytemia in symptomatic patients in an area of intense perennial transmission in Tanzania.

Cited by 61 publications

References 22 publications

High Prevalence of Gametocyte Carriage among Individuals with Asymptomatic Malaria: Implications for Sustaining Malaria Control and Elimination Efforts in Ethiopia

High Prevalence of Gametocyte Carriage among Individuals with Asymptomatic Malaria: Implications for Sustaining Malaria Control and Elimination Efforts in Ethiopia

Competitive facilitation of drug-resistant Plasmodium falciparum malaria parasites in pregnant women who receive preventive treatment

Infectivity of <i>Plasmodium falciparum</i> gametocytes in patients attending rural health centres in western Kenya

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