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1.
Eur J Cancer Prev ; 2024 Aug 29.
Artículo en Inglés | MEDLINE | ID: mdl-39230048

RESUMEN

Human papillomavirus (HPV) coinfection remains common globally. However, its clinical significance compared to mono-infection remains controversial. Further, the epidemiology of HPV genotype combination in coinfection is not well studied in Kenya. . Between June and August 2023, a cross-sectional facility-based survey enrolled 434 women aged 16-68 years using purposive sampling strategy. Structured questionnaire was obtained from each woman regarding demographic and sexual behavior characteristics. Cervical specimen was collected from each participant and analyzed using RIATOL assay to determine HPV genotypes and viral load. Overall, HPV 52 was the most frequently detected HPV strain. The mean HPV viral load was elevated among coinfected women than those with mono-infection but there was no evidence to support differences in viral load in the two groups (P = 0.113). Mono-infection was common (58.52%). HPV 16 was noted to have a near equal presence both in mono-infection and coinfection (52.17% and 47. 83%), respectively. HPV 33 (alpha 9) and 45 (alpha 7) had the greatest preference for each other compared to all other HPV interactions. HPV 52 is the most prevalent HPV in the population supporting the need for the nonavalent HPV vaccine. Mono-infection with HPV 16 remains common corroborating the relevance of bivalent vaccine in resource limited setting where nonavalent vaccines may be unavailable. The frequent coinfection preference of HPV 33 and 45 (alpha 9 and alpha 7, respectively) pauses the need for further concurrent characterization. HPV vaccination and education on safe sexual behaviors is key in reducing HPV coinfection.

2.
Am J Hum Genet ; 111(7): 1243-1251, 2024 07 11.
Artículo en Inglés | MEDLINE | ID: mdl-38996465

RESUMEN

Population history-focused DNA and ancient DNA (aDNA) research in Africa has dramatically increased in the past decade, enabling increasingly fine-scale investigations into the continent's past. However, while international interest in human genomics research in Africa grows, major structural barriers limit the ability of African scholars to lead and engage in such research and impede local communities from partnering with researchers and benefitting from research outcomes. Because conversations about research on African people and their past are often held outside Africa and exclude African voices, an important step for African DNA and aDNA research is moving these conversations to the continent. In May 2023 we held the DNAirobi workshop in Nairobi, Kenya and here we synthesize what emerged most prominently in our discussions. We propose an ideal vision for population history-focused DNA and aDNA research in Africa in ten years' time and acknowledge that to realize this future, we need to chart a path connecting a series of "landmarks" that represent points of consensus in our discussions. These include effective communication across multiple audiences, reframed relationships and capacity building, and action toward structural changes that support science and beyond. We concluded there is no single path to creating an equitable and self-sustaining research ecosystem, but rather many possible routes linking these landmarks. Here we share our diverse perspectives as geneticists, anthropologists, archaeologists, museum curators, and educators to articulate challenges and opportunities for African DNA and aDNA research and share an initial map toward a more inclusive and equitable future.


Asunto(s)
ADN Antiguo , Genética de Población , Humanos , ADN Antiguo/análisis , África , Genómica , Población Negra/genética
3.
J Pediatric Infect Dis Soc ; 13(5): 288-296, 2024 May 30.
Artículo en Inglés | MEDLINE | ID: mdl-38512283

RESUMEN

BACKGROUND: Subclinical inflammation and cognitive deficits have been separately associated with asymptomatic Plasmodium falciparum infections in schoolchildren. However, whether parasite-induced inflammation is associated with worse cognition has not been addressed. We conducted a cross-sectional pilot study to better assess the effect of asymptomatic P. falciparum parasitemia and inflammation on cognition in Kenyan schoolchildren. METHODS: We enrolled 240 children aged 7-14 years residing in high malaria transmission in Western Kenya. Children performed five fluid cognition tests from a culturally adapted NIH toolbox and provided blood samples for blood smears and laboratory testing. Parasite densities and plasma concentrations of 14 cytokines were determined by quantitative PCR and multiplex immunoassay, respectively. Linear regression models were used to determine the effects of parasitemia and plasma cytokine concentrations on each of the cognitive scores as well as a composite cognitive score while controlling for age, gender, maternal education, and an interaction between age and P. falciparum infection status. RESULTS: Plasma concentrations of TNF, IL-6, IL-8, and IL-10 negatively correlated with the composite score and at least one of the individual cognitive tests. Parasite density in parasitemic children negatively correlated with the composite score and measures of cognitive flexibility and attention. In the adjusted model, parasite density and TNF, but not P. falciparum infection status, independently predicted lower cognitive composite scores. By mediation analysis, TNF significantly mediated ~29% of the negative effect of parasitemia on cognition. CONCLUSIONS: Among schoolchildren with PCR-confirmed asymptomatic P. falciparum infections, the negative effect of parasitemia on cognition could be mediated, in part, by subclinical inflammation. Additional studies are needed to validate our findings in settings of lower malaria transmission and address potential confounders that could affect both inflammation and cognitive performance.


Asunto(s)
Inflamación , Malaria Falciparum , Parasitemia , Plasmodium falciparum , Humanos , Niño , Malaria Falciparum/sangre , Malaria Falciparum/complicaciones , Masculino , Parasitemia/sangre , Femenino , Estudios Transversales , Adolescente , Inflamación/sangre , Kenia/epidemiología , Citocinas/sangre , Proyectos Piloto , Infecciones Asintomáticas , Disfunción Cognitiva/parasitología , Disfunción Cognitiva/sangre , Disfunción Cognitiva/etiología
4.
J Int Neuropsychol Soc ; 29(10): 933-942, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-37989561

RESUMEN

OBJECTIVE: Our objective was to evaluate the psychometric properties of the culturally adapted NIH Toolbox African Languages® when used in Swahili and Dholuo-speaking children in western Kenya. METHOD: Swahili-speaking participants were recruited from Eldoret and Dholuo-speaking participants from Ajigo; all were <14 years of age and enrolled in primary school. Participants completed a demographics questionnaire and five fluid cognition tests of the NIH Toolbox® African Languages program, including Flanker, Dimensional Change Card Sort (DCCS), Picture Sequence Memory, Pattern Comparison, and List Sorting tests. Statistical analyses examined aspects of reliability, including internal consistency (in both languages) and test-retest reliability (in Dholuo only). RESULTS: Participants included 479 children (n = 239, Swahili-speaking; n = 240, Dholuo-speaking). Generally, the tests had acceptable psychometric properties for research use within Swahili- and Dholuo-speaking populations (mean age = 10.5; SD = 2.3). Issues related to shape identification and accuracy over speed limited the utility of DCCS for many participants, with approximately 25% of children unable to match based on shape. These cultural differences affected outcomes of reliability testing among the Dholuo-speaking cohort, where accuracy improved across all five tests, including speed. CONCLUSIONS: There is preliminary evidence that the NIH Toolbox ® African Languages potentially offers a valid assessment of development and performance using tests of fluid cognition in Swahili and Dholuo among research settings. With piloting underway across other diverse settings, future research should gather additional evidence on the clinical utility and acceptability of these tests, specifically through the establishment of norming data among Kenyan regions and evaluating these psychometric properties.


Asunto(s)
Cognición , Lenguaje , Humanos , Niño , Adolescente , Kenia , Psicometría , Reproducibilidad de los Resultados , Pruebas Neuropsicológicas
5.
Nature ; 615(7954): 866-873, 2023 03.
Artículo en Inglés | MEDLINE | ID: mdl-36991187

RESUMEN

The urban peoples of the Swahili coast traded across eastern Africa and the Indian Ocean and were among the first practitioners of Islam among sub-Saharan people1,2. The extent to which these early interactions between Africans and non-Africans were accompanied by genetic exchange remains unknown. Here we report ancient DNA data for 80 individuals from 6 medieval and early modern (AD 1250-1800) coastal towns and an inland town after AD 1650. More than half of the DNA of many of the individuals from coastal towns originates from primarily female ancestors from Africa, with a large proportion-and occasionally more than half-of the DNA coming from Asian ancestors. The Asian ancestry includes components associated with Persia and India, with 80-90% of the Asian DNA originating from Persian men. Peoples of African and Asian origins began to mix by about AD 1000, coinciding with the large-scale adoption of Islam. Before about AD 1500, the Southwest Asian ancestry was mainly Persian-related, consistent with the narrative of the Kilwa Chronicle, the oldest history told by people of the Swahili coast3. After this time, the sources of DNA became increasingly Arabian, consistent with evidence of growing interactions with southern Arabia4. Subsequent interactions with Asian and African people further changed the ancestry of present-day people of the Swahili coast in relation to the medieval individuals whose DNA we sequenced.


Asunto(s)
Pueblo Africano , Asiático , Genética de Población , Femenino , Humanos , Masculino , Pueblo Africano/genética , Asiático/genética , Historia Medieval , Océano Índico , Tanzanía , Kenia , Mozambique , Comoras , Historia del Siglo XV , Historia del Siglo XVI , Historia del Siglo XVII , India/etnología , Persia/etnología , Arabia/etnología , ADN Antiguo/análisis
6.
Malar J ; 21(1): 337, 2022 Nov 16.
Artículo en Inglés | MEDLINE | ID: mdl-36380379

RESUMEN

BACKGROUND: Accurate detection of asymptomatic malaria parasitaemia in children living in high transmission areas is important for malaria control and reduction programmes that employ screen-and-treat surveillance strategies. Relative to microscopy and conventional rapid diagnostic tests (RDTs), ultrasensitive RDTs (us-RDTs) have demonstrated reduced limits of detection with increased sensitivity to detect parasitaemia in symptomatic individuals. In this study, the performance of the NxTek™ Eliminate Malaria P.f test was compared with traditional microscopy and quantitative polymerase chain reaction (qPCR) testing methods of detection for P. falciparum parasitaemia among asymptomatic children aged 7-14 years living in an area of high malaria transmission intensity in western Kenya. METHODS: In October 2020, 240 healthy children without any reported malaria symptoms were screened for the presence of P. falciparum parasitaemia; 120 children were randomly selected to participate in a follow-up visit at 6-10 weeks. Malaria parasitaemia was assessed by blood-smear microscopy, us-RDT, and qPCR of a conserved var gene sequence from genomic DNA extracted from dried blood spots. Sensitivity, specificity, and predictive values were calculated for field diagnostic methods using qPCR as the gold standard. Comparison of detectable parasite density distributions and area under the curve were also calculated to determine the effectiveness of the us-RDT in detecting asymptomatic infections with low parasite densities. RESULTS: The us-RDT detected significantly more asymptomatic P. falciparum infections than microscopy (42.5% vs. 32.2%, P = 0.002). The positive predictive value was higher for microscopy (92.2%) than for us-RDT (82.4%). However, false negative rates were high for microscopy and us-RDT, with negative predictive values of 53.7% and 54.6%, respectively. While us-RDT detected significantly more infections than microscopy overall, the density distribution of detectable infections did not differ (P = 0.21), and qPCR detected significantly more low-density infections than both field methods (P < 0.001, for both comparisons). CONCLUSIONS: Us-RDT is more sensitive than microscopy for detecting asymptomatic malaria parasitaemia in children. Though the detectable parasite density distributions by us-RDT in our specific study did not significantly differ from microscopy, the additional sensitivity of the us-RDT resulted in more identified asymptomatic infections in this important group of the population and makes the use of the us-RDT advisable compared to other currently available malaria field detection methods.


Asunto(s)
Malaria Falciparum , Plasmodium falciparum , Niño , Humanos , Antígenos de Protozoos , Infecciones Asintomáticas/epidemiología , Pruebas Diagnósticas de Rutina/métodos , Kenia , Malaria Falciparum/epidemiología , Parasitemia/parasitología , Sensibilidad y Especificidad
7.
Adv Virol ; 2022: 3217749, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35186083

RESUMEN

HIV-1 genetic diversity results into the development of widespread drug-resistant mutations (DRMs) for the first-line retroviral therapy. Nevertheless, few studies have investigated the relationship between DRMs and HIV-1 subtypes among HIV-positive injecting drug users (IDUs). This study therefore determined the association between HIV-1 genotypes and DRMs among the 200 IDUs. Stanford HIV Drug Resistance Database was used to interpret DRMs. The five HIV-1 genotypes circulating among the IDUs were A1 (25 (53.2%)), A2 (2 (4.3%)), B (2 (4.3%)), C (9 (19.1%)), and D (9 (19.1%)). The proportions of DRMs were A1 (12 (52.2%)), A2 (1 (4.3%)), B (0 (0.0%)), C (5 (21.7%)), and D (5 (21.7%)). Due to the large proportion of drug resistance across all HIV-1 subtypes, surveillance and behavioral studies need to be explored as IDUs may be spreading the drug resistance to the general population. In addition, further characterization of DRMs including all the relevant clinical parameters among the larger population of IDUs is critical for effective drug resistance surveillance.

8.
Nature ; 603(7900): 290-296, 2022 03.
Artículo en Inglés | MEDLINE | ID: mdl-35197631

RESUMEN

Multiple lines of genetic and archaeological evidence suggest that there were major demographic changes in the terminal Late Pleistocene epoch and early Holocene epoch of sub-Saharan Africa1-4. Inferences about this period are challenging to make because demographic shifts in the past 5,000 years have obscured the structures of more ancient populations3,5. Here we present genome-wide ancient DNA data for six individuals from eastern and south-central Africa spanning the past approximately 18,000 years (doubling the time depth of sub-Saharan African ancient DNA), increase the data quality for 15 previously published ancient individuals and analyse these alongside data from 13 other published ancient individuals. The ancestry of the individuals in our study area can be modelled as a geographically structured mixture of three highly divergent source populations, probably reflecting Pleistocene interactions around 80-20 thousand years ago, including deeply diverged eastern and southern African lineages, plus a previously unappreciated ubiquitous distribution of ancestry that occurs in highest proportion today in central African rainforest hunter-gatherers. Once established, this structure remained highly stable, with limited long-range gene flow. These results provide a new line of genetic evidence in support of hypotheses that have emerged from archaeological analyses but remain contested, suggesting increasing regionalization at the end of the Pleistocene epoch.


Asunto(s)
Población Negra , ADN Antiguo , Genética de Población , África del Sur del Sahara , Arqueología , Población Negra/genética , Población Negra/historia , ADN Antiguo/análisis , Flujo Génico/genética , Genoma Humano/genética , Historia Antigua , Humanos
9.
J Int Neuropsychol Soc ; 28(4): 414-423, 2022 04.
Artículo en Inglés | MEDLINE | ID: mdl-34027848

RESUMEN

OBJECTIVES: Performing high-quality and reliable cognitive testing requires significant resources and training. As a result, large-scale studies involving cognitive testing are difficult to perform in low- and middle-income settings, limiting access to critical knowledge to improve academic achievement and economic production in these populations. The NIH Toolbox® is a collection of cognitive, motor, sensory, and emotional tests that can be administered and scored using an iPad® tablet, reducing the need for training and quality monitoring; and thus, it is a potential solution to this problem. METHODS: We describe our process for translation and cultural adaptation of the existing NIH Toolbox tests of fluid cognition into the Swahili and Dholuo languages for use in children aged 3-14 years in western Kenya. Through serial forward and back translations, cognitive interviews, group consensus, outside feedback, and support from the NIH Toolbox team, we produced translated tests that have both face validity and linguistic validation. RESULTS: During our cognitive interviews, we found that the five chosen tests (one each of attention, cognitive flexibility, working memory, episodic memory, and processing speed) were generally well understood by children aged 7-14 years in our chosen populations. The cognitive interviews informed alterations in translation as well as slight changes in some images to culturally adapt the tests. CONCLUSIONS: This study describes the process by which we translated five fluid cognition tests from the NIH Toolbox into the Swahili and Dholuo languages. The finished testing application will be available for future studies, including a pilot study for assessment of psychometric properties.


Asunto(s)
Cognición , Lenguaje , Niño , Humanos , Kenia , Pruebas Neuropsicológicas , Proyectos Piloto , Reproducibilidad de los Resultados
10.
Malar J ; 20(1): 371, 2021 Sep 17.
Artículo en Inglés | MEDLINE | ID: mdl-34535134

RESUMEN

BACKGROUND: Further reductions in malaria incidence as more countries approach malaria elimination require the identification and treatment of asymptomatic individuals who carry mosquito-infective Plasmodium gametocytes that are responsible for furthering malaria transmission. Assessing the relationship between total parasitaemia and gametocytaemia in field surveys can provide insight as to whether detection of low-density, asymptomatic Plasmodium falciparum infections with sensitive molecular methods can adequately detect the majority of infected individuals who are potentially capable of onward transmission. METHODS: In a cross-sectional survey of 1354 healthy children and adults in three communities in western Kenya across a gradient of malaria transmission (Ajigo, Webuye, and Kapsisywa-Kipsamoite), asymptomatic P. falciparum infections were screened by rapid diagnostic tests, blood smear, and quantitative PCR of dried blood spots targeting the varATS gene in genomic DNA. A multiplex quantitative reverse-transcriptase PCR assay targeting female and male gametocyte genes (pfs25, pfs230p), a gene with a transcriptional pattern restricted to asexual blood stages (piesp2), and human GAPDH was also developed to determine total parasite and gametocyte densities among parasitaemic individuals. RESULTS: The prevalence of varATS-detectable asymptomatic infections was greatest in Ajigo (42%), followed by Webuye (10%). Only two infections were detected in Kapsisywa. No infections were detected in Kipsamoite. Across all communities, children aged 11-15 years account for the greatest proportion total and sub-microscopic asymptomatic infections. In younger age groups, the majority of infections were detectable by microscopy, while 68% of asymptomatically infected adults (> 21 years old) had sub-microscopic parasitaemia. Piesp2-derived parasite densities correlated poorly with microscopy-determined parasite densities in patent infections relative to varATS-based detection. In general, both male and female gametocytaemia increased with increasing varATS-derived total parasitaemia. A substantial proportion (41.7%) of individuals with potential for onward transmission had qPCR-estimated parasite densities below the limit of microscopic detection, but above the detectable limit of varATS qPCR. CONCLUSIONS: This assessment of parasitaemia and gametocytaemia in three communities with different transmission intensities revealed evidence of a substantial sub-patent infectious reservoir among asymptomatic carriers of P. falciparum. Experimental studies are needed to definitively determine whether the low-density infections in communities such as Ajigo and Webuye contribute significantly to malaria transmission.


Asunto(s)
Infecciones Asintomáticas/epidemiología , Malaria Falciparum/epidemiología , Población Rural/estadística & datos numéricos , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Preescolar , Estudios Transversales , Femenino , Humanos , Lactante , Kenia/epidemiología , Masculino , Persona de Mediana Edad , Prevalencia , Adulto Joven
11.
J Exp Med ; 218(9)2021 09 06.
Artículo en Inglés | MEDLINE | ID: mdl-34342640

RESUMEN

We previously identified a Plasmodium falciparum (Pf) protein of unknown function encoded by a single-copy gene, PF3D7_1134300, as a target of antibodies in plasma of Tanzanian children in a whole-proteome differential screen. Here we characterize this protein as a blood-stage antigen that localizes to the surface membranes of both parasitized erythrocytes and merozoites, hence its designation as Pf erythrocyte membrane and merozoite antigen 1 (PfEMMA1). Mouse anti-PfEMMA1 antisera and affinity-purified human anti-PfEMMA1 antibodies inhibited growth of P. falciparum strains by up to 68% in growth inhibition assays. Following challenge with uniformly fatal Plasmodium berghei (Pb) ANKA, up to 40% of mice immunized with recombinant PbEMMA1 self-cured, and median survival of lethally infected mice was up to 2.6-fold longer than controls (21 vs. 8 d, P = 0.005). Furthermore, high levels of naturally acquired human anti-PfEMMA1 antibodies were associated with a 46% decrease in parasitemia over 2.5 yr of follow-up of Tanzanian children. Together, these findings suggest that antibodies to PfEMMA1 mediate protection against malaria.


Asunto(s)
Antígenos de Protozoos/metabolismo , Membrana Eritrocítica/parasitología , Malaria Falciparum/parasitología , Merozoítos/metabolismo , Plasmodium falciparum/fisiología , Proteínas Protozoarias/genética , Animales , Anticuerpos Antiprotozoarios/inmunología , Antígenos de Protozoos/genética , Antígenos de Protozoos/inmunología , Preescolar , Femenino , Interacciones Huésped-Parásitos/fisiología , Humanos , Lactante , Vacunas contra la Malaria/genética , Vacunas contra la Malaria/inmunología , Malaria Falciparum/inmunología , Malaria Falciparum/mortalidad , Merozoítos/inmunología , Ratones Endogámicos BALB C , Plasmodium falciparum/inmunología , Plasmodium falciparum/patogenicidad , Polimorfismo de Nucleótido Simple , Proteínas Protozoarias/química , Proteínas Protozoarias/inmunología , Proteínas Protozoarias/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/inmunología , Proteínas Recombinantes/metabolismo , Tanzanía
12.
BMC Health Serv Res ; 21(1): 795, 2021 Aug 11.
Artículo en Inglés | MEDLINE | ID: mdl-34380493

RESUMEN

BACKGROUND: Understanding the existing barriers to utilization of maternal and newborn health care services can inform improvement of care services in the rural settings in sub-Saharan Africa. However, how unintended pregnancy relates to the uptake of antenatal care (ANC) services and also how gaps in the role of the community health workers and health facilities affect maternal and newborn care and referral services are poorly understood. METHODS: This was a formative ethnographic study design to determine barriers to the utilization of health care services for maternal and newborns in rural Western Kenya. We interviewed 45 respondents through in-depth interviews in rural Bondo Sub- County, Western Kenya: Mothers and Fathers with children under 5 years), 2 Focus Group Discussions (FGDs) with Traditional Birth Attendants (TBA), and 2 FGDs with Skilled Birth Attendants (SBAs). The data were analyzed using Atlas-ti. RESULTS: We found that unintended pregnancy results into poor uptake of antenatal care (ANC) services due to limited knowledge and poor support system. The respondents appreciated the role of community health workers but poor government infrastructure exists. Also, perceived harshness of the health care providers, poor management of high-risk pregnancies, and unavailability of supplies and equipment at the health facilities are of concern. CONCLUSIONS: The findings of this study highlight barriers to the utilization of maternal and newborn services that if addressed can improve the quality of care within and outside health facilities.


Asunto(s)
Servicios de Salud Materna , Servicios de Salud Rural , Niño , Preescolar , Agentes Comunitarios de Salud , Femenino , Accesibilidad a los Servicios de Salud , Humanos , Recién Nacido , Kenia , Embarazo , Atención Prenatal , Investigación Cualitativa , Población Rural
13.
Am J Trop Med Hyg ; 103(6): 2183-2188, 2020 12.
Artículo en Inglés | MEDLINE | ID: mdl-33146104

RESUMEN

In epidemic-prone areas of the western highlands, the Kenya Ministry of Health conducted campaigns of indoor residual spraying (IRS) of households, followed by mass distribution of insecticide-treated bed nets (ITNs), as part of the National Malaria Strategy. We previously reported that in the highland areas of Kipsamoite and Kapsisiywa, widespread IRS coverage in 2007, after lower but substantial coverage in 2005 and 2006, contributed to possible local interruption of malaria transmission between 2007 and 2008. Indoor residual spraying campaigns in the area ended in 2010, succeeded by a mass ITN distribution campaign in 2011 and 2012 targeting universal coverage. Insecticide-treated bed net use in the area increased from 17.1% pre-campaign in 2011 to 51.7% post-campaign in 2012, but decreased to 35.8% in 2013. The ITN campaign did not reduce malaria incidence in the population as a whole (odds ratio [OR] after ITN distribution versus before, 1.29, 95% CI: 1.00-1.66, P = 0.049). However, in 2011-2013, individuals who stated that they slept under ITNs as compared with those who did not had a decrease in malaria incidence that approached statistical significance (OR 0.74, 95% CI: 0.52-1.04, P = 0.08). Mass ITN distribution after previous annual IRS campaigns was insufficient to further reduce malaria transmission in this area of low and highly seasonal transmission possibly because of low ITN use despite the mass campaign.


Asunto(s)
Epidemias , Mosquiteros Tratados con Insecticida , Malaria/prevención & control , Adolescente , Clima , Demografía , Composición Familiar , Femenino , Humanos , Incidencia , Kenia/epidemiología , Malaria/epidemiología , Masculino , Riesgo
14.
Am J Trop Med Hyg ; 103(6): 2174-2182, 2020 12.
Artículo en Inglés | MEDLINE | ID: mdl-33124533

RESUMEN

Immune correlates of protection against clinical malaria are difficult to ascertain in low-transmission areas because of the limited number of malaria cases. We collected blood samples from 5,753 individuals in a Kenyan highland area, ascertained malaria incidence in this population over the next 6 years, and then compared antibody responses to 11 Plasmodium falciparum vaccine candidate antigens in individuals who did versus did not develop clinical malaria in a nested case-control study (154 cases and 462 controls). Individuals were matched by age and village. Antigens tested included circumsporozoite protein (CSP), liver-stage antigen (LSA)-1, apical membrane antigen-1 FVO and 3D7 strains, erythrocyte-binding antigen-175, erythrocyte-binding protein-2, merozoite surface protein (MSP)-1 FVO and 3D7 strains, MSP-3, and glutamate-rich protein (GLURP) N-terminal non-repetitive (R0) and C-terminal repetitive (R2) regions. After adjustment for potential confounding factors, the presence of antibodies to LSA-1, GLURP-R2, or GLURP-R0 was associated with decreased odds of developing clinical malaria (odds ratio [OR], [95% CI] 0.56 [0.36-0.89], 0.56 [0.36-0.87], and 0.77 [0.43-1.02], respectively). Levels of antibodies to LSA-1, GLURP-R2, and CSP were associated with decreased odds of developing clinical malaria (OR [95% CI]; 0.61 [0.41-0.89], 0.60 [0.43-0.84], and 0.49 [0.24-0.99], for every 10-fold increase in antibody levels, respectively). The presence of antibodies to CSP, GLURP-R0, GLURP-R2, and LSA-1 combined best-predicted protection from clinical malaria. Antibodies to CSP, GLURP-R0, GLURP-R2, and LSA-1 are associated with protection against clinical malaria in a low-transmission setting. Vaccines containing these antigens should be evaluated in low malaria transmission areas.


Asunto(s)
Anticuerpos Antiprotozoarios/inmunología , Antígenos de Protozoos/inmunología , Malaria Falciparum/inmunología , Plasmodium falciparum/inmunología , Proteínas Protozoarias/inmunología , Adolescente , Adulto , Anciano , Formación de Anticuerpos , Estudios de Casos y Controles , Niño , Preescolar , Femenino , Humanos , Incidencia , Kenia/epidemiología , Malaria Falciparum/epidemiología , Malaria Falciparum/prevención & control , Malaria Falciparum/transmisión , Masculino , Persona de Mediana Edad
15.
Am J Trop Med Hyg ; 103(6): 2198-2207, 2020 12.
Artículo en Inglés | MEDLINE | ID: mdl-33124534

RESUMEN

The use of spatial data in malaria elimination strategies is important to understand whether targeted interventions against malaria can be used, particularly in areas with limited resources. We previously documented consistent areas of increased malaria incidence in the epidemic-prone area of Kipsamoite in highland Kenya from 2001 to 2004. In this area and a neighboring subcounty (Kapsisiywa), malaria incidence decreased substantially in 2005, going from peak incidence of 31.7 per 1,000 persons in June 2004 to peak incidence of 7.4 per 1,000 persons in May 2005. Subsequently, the use of indoor residual spraying and artemisinin combination therapy malaria treatment led to a possible interruption of malaria transmission for a 13-month period from 2007 to 2008, after which the incidence returned to very low levels until an epidemic in April-July 2013. In the present study, we used novel kernel density estimation methods to determine whether areas of increased malaria incidence were consistent in six periods of peak incidence from 2003 to 2013, and to assess patterns of incidence in the period before versus. after the period of possible interruption. Areas of highest incidence differed during peak malaria transmission periods over the years 2003-2013, and differed before and after the potential malaria interruption. In this epidemic-prone region with very low malaria transmission, consistent malaria "hotspots" identified in a time of higher transmission are no longer present. Ongoing assessment of spatial malaria epidemiology to identify and target current areas of elevated malaria risk may be important in campaigns to control or eliminate malaria in epidemic-prone areas.


Asunto(s)
Antiinfecciosos/uso terapéutico , Artemisininas/uso terapéutico , Malaria/epidemiología , Punto Alto de Contagio de Enfermedades , Humanos , Incidencia , Kenia/epidemiología , Estudios Longitudinales , Malaria/tratamiento farmacológico , Malaria/parasitología , Malaria/transmisión
16.
Am J Trop Med Hyg ; 103(6): 2189-2197, 2020 12.
Artículo en Inglés | MEDLINE | ID: mdl-33124539

RESUMEN

Prevalence and levels of antibodies to multiple Plasmodium falciparum antigens show promise as tools for estimating malaria exposure. In a highland area of Kenya with unstable transmission, we assessed the presence and levels of antibodies to 12 pre-erythrocytic and blood-stage P. falciparum antigens by multiplex cytometric bead assay or ELISA in 604 individuals in August 2007, with follow-up testing in this cohort in April 2008, April 2009, and May 2010. Four hundred individuals were tested at all four time points. During this period, the only substantial malaria incidence occurred from April to August 2009. Antibody prevalence in adults was high at all time points (> 70%) for apical membrane antigen 1, erythrocyte-binding antigen 175, erythrocyte-binding protein-2, glutamate rich protein (GLURP)-R2, merozoite surface protein (MSP) 1 (19), MSP-1 (42), and liver-stage antigen-1; moderate (30-70%) for GLURP-R0, MSP-3, and thrombospondin-related adhesive protein; and low (< 30%) for SE and circumsporozoite protein (CSP). Changes in community-wide malaria exposure were best reflected in decreasing antibody levels overtime for highly immunogenic antigens, and in antibody seroprevalence overtime for the less-immunogenic antigens. Over the 3 years, antibody levels to all antigens except CSP and schizont extract (SE) decreased in an age-dependent manner. Prevalence and levels of antibodies to all antigens except CSP and SE increased with age. Increases in antibody prevalence and levels to CSP and SE coincided with increases in community-wide malaria incidence. Antibody levels to multiple P. falciparum antigens decrease in the absence of consistent transmission. Multiplex assays that assess both the presence and level of antibodies to multiple pre-erythrocytic and blood-stage P. falciparum antigens may provide the most useful estimates of past and recent malaria transmission in areas of unstable transmission and could be useful tools in malaria control and elimination campaigns.


Asunto(s)
Anticuerpos Antiprotozoarios/sangre , Antígenos de Protozoos/inmunología , Malaria Falciparum/epidemiología , Malaria/epidemiología , Plasmodium falciparum/inmunología , Plasmodium/inmunología , Adolescente , Niño , Preescolar , Estudios de Cohortes , Erradicación de la Enfermedad , Ensayo de Inmunoadsorción Enzimática , Eritrocitos/parasitología , Humanos , Incidencia , Lactante , Kenia/epidemiología , Malaria/parasitología , Malaria/transmisión , Malaria Falciparum/parasitología , Malaria Falciparum/transmisión , Modelos Estadísticos , Prevalencia , Estudios Seroepidemiológicos
17.
Int J Microbiol ; 2020: 3406461, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32908522

RESUMEN

Cassava (Manihot esculenta Crantz) is a major source of carbohydrates, calcium, vitamins (B and C), and essential minerals and is the third most important source of calories in the tropics. However, it is not clear if the traditional processing methods expose the products to microbial contamination. This study assessed the levels of fungi and aflatoxin contamination in traditionally processed cassava products (Akuoga and Abeta). A total of 38 samples were collected from the local markets in 7 subcounties in Homa Bay County, Kenya. The levels of aflatoxin were determined using an indirect competitive ELISA protocol. Yeast and mould contamination was determined using ISO 21527-2 method. Mean aflatoxin levels in chopped, fermented, and sun-dried cassava (Akuoga) were 0.36 µg/kg compared to 0.25 µg/kg in chopped and sun-dried (Abeta) products. Aflatoxin contamination was detected in 55% of the samples and ranged from 0-5.33 µg/kg. These levels are within 10 µg/kg recommended by the CODEX STAN 193-1995. Yeast and mould counts in fermented and chopped sun-dried products were 3.16 log Cfu/g and 2.92 log Cfu/g, respectively. The yeast and mould counts were above standards set by East African Standard 739:2010 in 62% (Akuoga) and 58% (Abeta). The most prevalent fungal species were Saccharomyces cerevisiae (68.4%) and Candida rugosa (68%) followed by Candida parapsilosis (18.4%), Candida tropicalis (15.8%), Candida humilis (15.8%), and Aspergillus spp. (5.3%). Aspergillus spp. was the only mycotoxigenic mould isolated from the samples. The study shows that cassava consumers are exposed to the risk of aflatoxin poisoning. The study, therefore, recommends appropriate surveillance to ensure safety standards.

18.
PLoS One ; 15(3): e0229871, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32126117

RESUMEN

An understanding of menstruation and its relationship to fertility can help women know the gestational age of any pregnancies, and thus identify preterm births. It can also help women avoid unintended pregnancies. However, little is known about women, and especially men's, menstruation and fertility knowledge, outside of research on adolescent girls and stigma, and in low and middle income countries (LMIC). Additionally, little is known about practices surrounding the tracking of menstruation and fertility, and how, if at all, women would like to be supported in this. This research is the first phase in adapting a support tool for women in a LMIC, using an implementation science approach to understand relevant cultural needs. We explored women and men's understanding of the relationship between menstruation and fertility, and their interest in support tools, through in-depth qualitative interviews in rural western Kenya. We interviewed 45 adult men, adult women and adolescent women all who had children in 2018. We found high levels of misinformation about menstruation and fertility, with most respondents not knowing the correct times when a woman could become pregnant. Common sources of knowledge included friends/family and school. Few women got information from health providers, even when they were at a facility already for care. There were mixed feelings from women about wanting support from male partners regarding tracking menstruation. While women were interested in a tool that could help them track their menstruation and pregnancies, they had privacy concerns about a mobile health app approach and preferred simpler calendar based tools. This study provides evidence for the high need for correct menstruation information among both men and women, and not only for adolescents. It also suggests that despite the international health community's enthusiasm for mobile health solutions, that approach might not be most appropriate for this topic and setting.


Asunto(s)
Fertilidad/fisiología , Conocimientos, Actitudes y Práctica en Salud , Menstruación/psicología , Adulto , Femenino , Humanos , Kenia/epidemiología , Masculino , Menstruación/fisiología , Pobreza , Embarazo , Población Rural , Adulto Joven
19.
Malar J ; 18(1): 297, 2019 Aug 30.
Artículo en Inglés | MEDLINE | ID: mdl-31470903

RESUMEN

BACKGROUND: HIV infection is associated with more frequent and severe episodes of malaria and may be the result of altered malaria-specific B cell responses. However, it is poorly understood how HIV and the associated lymphopenia and immune activation affect malaria-specific antibody responses. METHODS: HIV infected and uninfected adults were recruited from Bondo subcounty hospital in Western Kenya at the time of HIV testing (antiretroviral and co-trimoxazole prophylaxis naïve). Total and Plasmodium falciparum apical membrane antigen-1 (AMA1) and glutamate rich protein-R0 (GLURP-R0) specific IgM, IgG and IgG subclass concentrations was measured in 129 and 52 of recruited HIV-infected and uninfected individuals, respectively. In addition, HIV-1 viral load (VL), CD4+ T cell count, and C-reactive protein (CRP) concentration was quantified in study participants. Antibody levels were compared based on HIV status and the associations of antibody concentration with HIV-1 VL, CD4+ count, and CRP levels was measured using Spearman correlation testing. RESULTS: Among study participants, concentrations of IgM, IgG1 and IgG3 antibodies to AMA1 and GLURP-R0 were higher in HIV infected individuals compared to uninfected individuals (all p < 0.001). The IgG3 to IgG1 ratio to both AMA1 and GLURP-R0 was also significantly higher in HIV-infected individuals (p = 0.02). In HIV-infected participants, HIV-1 VL and CRP were weakly correlated with AMA1 and GLURP-R0 specific IgM and IgG1 concentrations and total (not antigen specific) IgM, IgG, IgG1, and IgG3 concentrations (all p < 0.05), suggesting that these changes are related in part to viral load and inflammation. CONCLUSIONS: Overall, HIV infection leads to a total and malaria antigen-specific immunoglobulin production bias towards higher levels of IgM, IgG1, and IgG3, and HIV-1 viraemia and systemic inflammation are weakly correlated with these changes. Further assessments of antibody affinity and function and correlation with risk of clinical malaria, will help to better define the effects of HIV infection on clinical and biological immunity to malaria.


Asunto(s)
Anticuerpos Antiprotozoarios/sangre , Infecciones por VIH/complicaciones , Inmunoglobulina G/sangre , Inmunoglobulina M/sangre , Malaria Falciparum/inmunología , Adulto , Anticuerpos Antiprotozoarios/inmunología , Afinidad de Anticuerpos , Antígenos de Protozoos/inmunología , Estudios Transversales , Femenino , Humanos , Kenia , Malaria Falciparum/sangre , Masculino , Proteínas de la Membrana/inmunología , Plasmodium falciparum/inmunología , Proteínas Protozoarias/inmunología , Adulto Joven
20.
Science ; 365(6448)2019 07 05.
Artículo en Inglés | MEDLINE | ID: mdl-31147405

RESUMEN

How food production first entered eastern Africa ~5000 years ago and the extent to which people moved with livestock is unclear. We present genome-wide data from 41 individuals associated with Later Stone Age, Pastoral Neolithic (PN), and Iron Age contexts in what are now Kenya and Tanzania to examine the genetic impacts of the spreads of herding and farming. Our results support a multiphase model in which admixture between northeastern African-related peoples and eastern African foragers formed multiple pastoralist groups, including a genetically homogeneous PN cluster. Additional admixture with northeastern and western African-related groups occurred by the Iron Age. These findings support several movements of food producers while rejecting models of minimal admixture with foragers and of genetic differentiation between makers of distinct PN artifacts.


Asunto(s)
Agricultura/historia , Genoma Humano , Migración Humana/historia , Ocupaciones/historia , ADN Antiguo , Historia Antigua , Humanos , Kenia , Tanzanía
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