RESUMO
Kenya has, in the last decade, made tremendous progress in the fight against malaria. Nevertheless, continued surveillance of the genetic diversity and population structure of Plasmodium falciparum is required to refine malaria control and to adapt and improve elimination strategies. Twelve neutral microsatellite loci were genotyped in 201 P. falciparum isolates obtained from the Kenyan-Ugandan border (Busia) and from two inland malaria-endemic sites situated in western (Nyando) and coastal (Msambweni) Kenya. Analyses were done to assess the genetic diversity (allelic richness and expected heterozygosity, [He ]), multilocus linkage disequilibrium ( ISA ) and population structure. A similarly high degree of genetic diversity was observed among the three parasite populations surveyed (mean He = 0.76; P > 0.05). Except in Msambweni, random association of microsatellite loci was observed, indicating high parasite out-breeding. Low to moderate genetic structure (FST = 0.022-0.076; P < 0.0001) was observed with only 5% variance in allele frequencies observed among the populations. This study shows that the genetic diversity of P. falciparum populations at the Kenyan-Ugandan border is comparable to the parasite populations from inland Kenya. In addition, high genetic diversity, panmixia and weak population structure in this study highlight the fitness of Kenyan P. falciparum populations to successfully withstand malaria control interventions.
Le Kenya a réalisé d'énormes progrès au cours de la dernière décennie dans la lutte contre le paludisme. Néanmoins, une surveillance continue de la diversité génétique et de la structure de la population de P. falciparum est nécessaire pour affiner la lutte contre le paludisme et pour adapter et améliorer les stratégies d'élimination. Douze loci microsatellites neutres ont été génotypés chez 201 isolats de P. falciparum provenant de la frontière entre le Kenya et l'Ouganda (Busia) et de deux sites d'endémie palustre situés dans l'ouest (Nyando) et sur la côte (Msambweni), au Kenya. Des analyses ont été effectuées pour évaluer la diversité génétique (richesse allélique et hétérozygotie attendue, ([He]), déséquilibre de parenté des multiple loci ( ISA ) et structure de la population. Un degré hautement similaire de diversité génétique a été observé parmi les trois populations de parasites étudiées (He = 0,76; P > 0,05). A l'exception de Msambweni, une association aléatoire entre les microsatellites a été observée, indiquant une forte reproduction des parasites. Une structure génétique faible à modérée (FST = 0,022-0,076; P < 0,0001) a été observée avec seulement 5% de variance dans la fréquence des allèles observée parmi les populations. Cette étude montre que la diversité génétique des populations de P. falciparum à la frontière entre le Kenya et l'Ouganda est comparable à celle des populations de parasites à l'intérieur du Kenya. De plus, la diversité génétique élevée, la panmixia et la structure démographique faible dans cette étude soulignent l'aptitude des populations de P. falciparum du Kenya à résister aux interventions de lutte contre le paludisme.
Assuntos
Alelos , Frequência do Gene , Variação Genética , Genótipo , Malária Falciparum/parasitologia , Repetições de Microssatélites , Plasmodium falciparum/genética , Controle de Doenças Transmissíveis , Genética Populacional , Humanos , Quênia , Desequilíbrio de Ligação , UgandaRESUMO
BACKGROUND: Injection drug use is steadily rising in Kenya. We assessed the prevalence of both human immunodeficiency virus type 1 (HIV-1) and hepatitis C virus (HCV) infections among injecting heroin users (IHUs) at the Kenyan Coast. METHODS: A total of 186 IHUs (mean age, 33 years) from the Omari rehabilitation center program in Malindi were consented and screened for HIV-1 and HCV by serology and PCR and their CD4 T-cells enumerated by FACS. RESULTS: Prevalence of HIV-1 was 87.5%, that of HCV was 16.4%, co-infection was 17.9% and 18/152 (11.8%) were uninfected. Only 5.26% of the HIV-1 negative injectors were HCV positive. Co-infection was higher among injectors aged 30 to 40 years (20.7%) and among males (22.1%) than comparable groups. About 35% of the injectors were receiving antiretroviral treatment (ART). Co-infection was highest among injectors receiving D4T (75%) compared to those receiving AZT (21.6%) or TDF (10.5%) or those not on ART (10.5%). Mean CD4 T-cells were 404 (95% CI, 365 - 443) cells/mm3 overall, significantly lower for co-infected (mean, 146; 95% CI 114 - 179 cells/mm3) than HIV mono infected (mean, 437, 95% CI 386 - 487 cells/mm3, p<0.001) or uninfected (mean, 618, 95% CI 549 - 687 cells/mm3, p<0.001) injectors and lower for HIV mono-infected than uninfected injectors (p=0.002). By treatment arm, CD4 T-cells were lower for injectors receiving D4T (mean, 78; 95% CI, 0.4 - 156 cells/mm3) than TDF (mean 607, 95% CI, 196 - 1018 cells/mm3, p=0.005) or AZT (mean 474, 95% CI -377 - 571 cells/mm3, p=0.004). CONCLUSION: Mono and dual infections with HIV-1 and HCV is high among IHUs in Malindi, but ART coverage is low. The co-infected IHUs have elevated risk of immunodeficiency due to significantly depressed CD4 T-cell numbers. Coinfection screening, treatment-as-prevention for both HIV and HCV and harm reduction should be scaled up to alleviate infection burden.
