The epidemiology of Plasmodium falciparum malaria in two Cameroonian villages: Simbok and Etoa.

Quakyi, Isabella A.; Befidi-Mengue, R; Tsafack, M; Bomba-Nkolo, Dennis; Manga, Lucien; Tchinda, V; Njeungue, E; Kouontchou, Samuel; Fogako, Josephine; Nyonglema, Philomina; Harun, Lucy; Djokam, Rosine; Sama, Grace; Eno, Anna; Megnekou, Rosette; Metenou, Simon; Ndountse, L; Same-Ekobo, A.; Alake, G; Meli, Josephine; Ngu, J. L.; Tietche, F; Lohoue, J.; Mvondo, J L; Wansi, E; Leke, Rose G. F.; Folefack, A; Bigoga, Jude D.; Bomba-Nkolo, C; Titanji, Vincent P. K.; Walker-Abbey, Annie; Hickey, Melissa; Johnson, Andrew F.; Taylor, Diane Wallace; Ndoutse, L

doi:10.4269/ajtmh.2000.63.222

Cited by 50 publications

(54 citation statements)

References 30 publications

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“…Because of the high rate of malaria transmission in Etoa, children acquire antibodies to many asexual-stage antigens by the time they reach 5 years of age (36). Thus, we determined if the proportion of individuals with antibodies (i.e., percent responders) to AMA1, MSA2, and MSP1-190L increased with age.…”

Section: Resultsmentioning

confidence: 99%

“…In 1995, a cross-sectional study was conducted in the rural village of Etoa, Cameroon. Etoa is a village of ϳ485 individuals where P. falciparum malaria is holoendemic (36). Malaria transmission is perennial with an estimated 2.4 infectious bites per night during each of the two rainy seasons and 0.4 infectious bites per night during the two dry seasons (36).…”

Section: Methodsmentioning

confidence: 99%

“…Etoa is a village of ϳ485 individuals where P. falciparum malaria is holoendemic (36). Malaria transmission is perennial with an estimated 2.4 infectious bites per night during each of the two rainy seasons and 0.4 infectious bites per night during the two dry seasons (36). Previous studies demonstrated that the prevalence of P. falciparum was ϳ65% in children 5 to 10 years, 34% in adolescents 11 to 15 years, and 29% in individuals over 15 years of age.…”

Section: Methodsmentioning

confidence: 99%

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Human Leukocyte Antigen Class II Alleles Influence Levels of Antibodies to thePlasmodium falciparumAsexual-Stage Apical Membrane Antigen 1 but Not to Merozoite Surface Antigen 2 and Merozoite Surface Protein 1

Johnson¹,

Leke

Mendell

et al. 2004

Infect Immun

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The apical membrane antigen 1 (AMA1), merozoite surface antigen 2 (MSA2), and merozoite surface protein 1 (MSP1) are asexual-stage proteins currently being evaluated for inclusion in a vaccine for Plasmodium falciparum. Accordingly, it is important to understand factors that control antibody responses to these antigens. Antibody levels in plasma from residents of Etoa, Cameroon, between the ages of 5 and 70 years, were determined using recombinant AMA1, MSA2, and the N-terminal region of MSP1 (MSP1-190L). In addition, antibody responses to four variants of the C-terminal region of MSP1 (MSP1 19 ) were assessed. Results showed that all individuals produced antibodies to AMA1, MSA2, and MSP1-190L; however, a proportion of individuals never produced antibodies to the MSP1 19 variants, although the percentage of nonresponders decreased with age. The influence of age and human leukocyte antigen (HLA)-DRB1/DQB1 alleles on antibody levels was evaluated using two-way analysis of variance. Age was correlated with levels of antibodies to AMA1 and MSP1 19 but not with levels of antibodies to MSA2 and MSP1-190L. No association was found between a single HLA allele and levels of antibodies to MSA2, MSP1-190L, or any of the MSP1 19 variants. However, individuals positive for DRB1*1201 had higher levels of antibodies to the variant of recombinant AMA1 tested than did individuals of all other HLA types. Since the effect was seen across all age groups, HLA influenced the level but not the rate of antibody acquisition. This association for AMA1, combined with the previously reported association between HLA class II alleles and levels of antibodies to rhoptry-associated protein 1 (RAP1) and RAP2, indicates that HLA influences the levels of antibodies to three of the five vaccine candidate antigens that we have evaluated.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Human Leukocyte Antigen Class II Alleles Influence Levels of Antibodies to thePlasmodium falciparumAsexual-Stage Apical Membrane Antigen 1 but Not to Merozoite Surface Antigen 2 and Merozoite Surface Protein 1

Johnson¹,

Leke

Mendell

et al. 2004

Infect Immun

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“…Malaria transmission is perennial at both sites, but it is considerably lower in urban Yaounde (entomological inoculation rate, 0.1 to 1.1/month) (15) than in rural Etoa (EIR, 0.4 to 2.4/day) (24). The study sites and populations have been described in detail elsewhere (33).…”

Section: Study Sites and Plasma Donorsmentioning

confidence: 99%

Effects of Pregnancy and Intensity of Plasmodium falciparum Transmission on Immunoglobulin G Subclass Responses to Variant Surface Antigens

et al. 2005

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Placenta-sequestering Plasmodium falciparum involved in the pathogenesis of pregnancy-associated malaria (PAM) in otherwise clinically immune women expresses particular variant surface antigens (VSA PAM ) on the surface of infected erythrocytes that differ from VSA found in parasitized nonpregnant individuals (non-PAM type VSA). We studied levels of immunoglobulin G (IgG) and IgG subclasses with specificity for VSA PAM and for non-PAM type VSA in pregnant and nonpregnant women from two sites with different endemicities in Cameroon. We found that VSA PAM -specific responses depended on the pregnancy status, parity, gestational age, and parasite transmission intensity, whereas only the parasite transmission intensity influenced the levels of IgG specific for non-PAM type VSA. For both types of VSA, the responses were dominated by the cytophilic subclass IgG1, followed by IgG3. In pregnant women, the levels of VSA PAM -specific antibodies either were very low or negative or were very high, whereas the levels of the antibodies specific for non-PAM type VSA were uniformly high. Interestingly, the levels of VSA PAM -specific IgG1 increased with increasing gestational age, while the levels of the corresponding IgG3 tended to decrease with increasing gestational age. The IgG subclass responses with specificity for non-PAM type VSA did not vary significantly with gestational age. Taken together, our data indicate that IgG1 and to a lesser extent IgG3 are the main subclasses involved in acquired VSA PAM -specific immunity to pregnancy-associated malaria.

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“…Malaria is prevalent throughout Cameroon with transmission being affected by climate and geography [1,2], increased drug resistance and the lack of adequate vector control measures [3]. Reduction in man-vector contact may be achieved by the use of protective clothing, insect repellents, bed nets, insecticides or environmental management.…”

Section: Introductionmentioning

confidence: 99%

Environmental factors affecting malaria parasite prevalence in rural Bolifamba, South- West Cameroon

Nkuo‐Akenji

Ntonifor²,

Ndukum³

et al. 2008

African Journal of Health Sciences

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SUMMARYThe impact of some environmental factors on malaria parasite prevalence was investigated in rural Bolifamba, Cameroon. The study population comprised 1454 subjects aged 0 -65 years. Malaria parasite prevalence was higher in the rainy (50.1%) than in the dry season (44.2%) with a significant difference (P=0.001) in mean parasite density between seasons. Individuals <15 years old, had significantly higher malaria parasite prevalence (55.5%) than those >15 years (37.4%). Malaria parasite prevalence (P=0.001) and parasite density (P=0.03) were higher in the individuals of wooden plank houses than those of cement brick houses. Inhabitants of houses surrounded by bushes or garbage heaps and swamps or stagnant water showed higher malaria parasite prevalence and densities compared with those from cleaner surroundings. Anopheles gambiae (63.8%) and A. funestus (32.8%) were associated with perennial transmission of malaria. Our data indicates that poor environmental sanitation and housing conditions may be significant risk factors for malaria parasite burden in Bolifamba.

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The epidemiology of Plasmodium falciparum malaria in two Cameroonian villages: Simbok and Etoa.

Cited by 50 publications

References 30 publications

Human Leukocyte Antigen Class II Alleles Influence Levels of Antibodies to thePlasmodium falciparumAsexual-Stage Apical Membrane Antigen 1 but Not to Merozoite Surface Antigen 2 and Merozoite Surface Protein 1

Human Leukocyte Antigen Class II Alleles Influence Levels of Antibodies to thePlasmodium falciparumAsexual-Stage Apical Membrane Antigen 1 but Not to Merozoite Surface Antigen 2 and Merozoite Surface Protein 1

Effects of Pregnancy and Intensity of Plasmodium falciparum Transmission on Immunoglobulin G Subclass Responses to Variant Surface Antigens

Environmental factors affecting malaria parasite prevalence in rural Bolifamba, South- West Cameroon

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