Perennial transmission of malaria in the low altitude areas of Baringo County, Kenya.

BACKGROUND: Malaria causes the greatest public health burden in sub-Saharan Africa where high mortality occurs mainly in children under 5 years of age. Traditionally, malaria has been reported mainly in the lowlands endemic regions of western Kenya, while the highlands of the Rift Valley have been relatively free except for the sporadic epidemics in some areas. Baringo County is located in the Kenyan highlands. The county generally experiences seasonal transmission of malaria. A few hotspots which experience continuous malaria transmission in the county do however exist. The objective of this study was to assess malaria infection status and identify areas with continuous transmissions with a view to mapping out probable transmission hot spots useful in mounting focused interventions within the county. METHODS: Systematic sampling was employed to identify 1668 primary school pupils from fifteen primary schools located in 4 ecological zones (lowland, midland, highland and riverine) of three sub-counties of Baringo. Finger prick blood sampling was done every 4 months (during the dry season in February/March, after the long rains in June/July and short rains in November 2015). Malaria occurrence was tested using rapid diagnostic test kit (CareStart HRP-2 Pf). Microscopic examination was done on all RDT positive and 10% of negative cases. RESULTS: A total of 268 (16.1%), out of 1668 pupils tested positive for Plasmodium falciparum by RDT; 78% had a single episode, 16.8% had 2 episodes, 4.9% had 3 episodes and 0.4% had 4 episodes. The riverine zone had the highest malaria cases (23.2%) followed by lowlands (0.9%). No malaria cases were detected in the midland zone while highland zone recorded only few cases during the third follow up. Up to 10.7% of malaria cases were reported in the dry season, 2.9% during the long rains and 5.7% in short rains season. CONCLUSIONS: Malaria infection was prevalent in Baringo County and was mainly restricted to the riverine zone where transmission is continuous throughout the year. High malaria prevalence occurred in the dry season compared to the wet season. Even though malaria transmission is relatively low compared to endemic regions of Kenya, there is a need for continued monitoring of transmission dynamics under changing climatic conditions as well as establishing expanded malaria control strategies especially within the riverine zone which would include an integrated mosquito control and chemotherapy for infected individuals.

Effect of climatic variability on malaria trends in Baringo County, Kenya.

BACKGROUND: Malaria transmission in arid and semi-arid regions of Kenya such as Baringo County, is seasonal and often influenced by climatic factors. Unravelling the relationship between climate variables and malaria transmission dynamics is therefore instrumental in developing effective malaria control strategies. The main aim of this study was to describe the effects of variability of rainfall, maximum temperature and vegetation indices on seasonal trends of malaria in selected health facilities within Baringo County, Kenya. METHODS: Climate variables sourced from the International Research Institute (IRI)/Lamont-Doherty Earth Observatory (LDEO) climate database and malaria cases reported in 10 health facilities spread across four ecological zones (riverine, lowland, mid-altitude and highland) between 2004 and 2014 were subjected to a time series analysis. A negative binomial regression model with lagged climate variables was used to model long-term monthly malaria cases. The seasonal Mann-Kendall trend test was then used to detect overall monotonic trends in malaria cases. RESULTS: Malaria cases increased significantly in the highland and midland zones over the study period. Changes in malaria prevalence corresponded to variations in rainfall and maximum temperature. Rainfall at a time lag of 2 months resulted in an increase in malaria transmission across the four zones while an increase in temperature at time lags of 0 and 1 month resulted in an increase in malaria cases in the riverine and highland zones, respectively. CONCLUSION: Given the existence of a time lag between climatic variables more so rainfall and peak malaria transmission, appropriate control measures can be initiated at the onset of short and after long rains seasons.

CD23-bound IgE augments and dominates recall responses through human naive B cells.

Human peripheral blood BCRµ(+) B cells express high levels of CD23 and circulate preloaded with IgE. The Ag specificity of CD23-bound IgE presumably differs from the BCR and likely reflects the Ag-specific mix of free serum IgE. CD23-bound IgE is thought to enhance B cell Ag presentation to T cells raising the question of how a B cell might respond when presented with a broad mix of Ags and CD23-bound IgE specificities. We recently reported that an increase in CD23(+) B cells is associated with the development of resistance to schistosomiasis, highlighting the potential importance of CD23-bound IgE in mediating immunity. We sought to determine the relationship between BCR and CD23-bound IgE-mediated B cell activation in the context of schistosomiasis. We found that crude schistosome Ags downregulate basal B cell activation levels in individuals hyperexposed to infectious worms. Schistosome-specific IgE from resistant, occupationally exposed Kenyans recovered responses of B cells to schistosome Ag. Furthermore, cross-linking of CD23 overrode intracellular signals mediated via the BCR, illustrating its critical and dominating role in B cell activation. These results suggest that CD23-bound IgE augments and dominates recall responses through naive B cells.

Intimate partner violence among pregnant women attending prenatal care in Bondo sub-county, Western Kenya.

OBJECTIVES: To investigate prevalence and factors that contribute to intimate partner violence among pregnant women attending prenatal care in Bondo sub-county, Western Kenya. METHODS: This cross-sectional analysis was conducted in three health facilities in Bondo, Western Kenya, from August 2020 to August 2021. Using systematic sampling 360 pregnant women attending prenatal care were selected. Structured questionnaires were used to collect data. Risk factors for intimate partner violence were determined using logistic regression. RESULTS: Out of the 360 respondents, 127 (35.3%) faced intimate partner violence during pregnancy. Among these, 86 (23.9%) experienced psychological violence, 56 (15.6%) experienced physical abuse, and 59 (16.4%) experienced sexual violence. Unemployment (adjusted odds ratio [aOR] 2.90; 95% confidence intervals [CI] 1.08-7.79), the inability to count on parents or siblings for support (aOR 2.48; 95% CI 1.14-5.43), and having a partner that drinks alcohol either daily (aOR 4.84; 95% CI 1.69-13.88) or occasionally (aOR 2.19; 95% CI 1.16-4.13) were independently associated with intimate partner violence during pregnancy. CONCLUSION: In this setting, intimate partner violence prevalence among pregnant women was high. Unemployment, having an alcohol-drinking partner, and the inability to count on parents or siblings for support were contributing factors.

Hepatitis B virus infection status and associated factors among health care workers in selected hospitals in Kisumu County, Kenya: A cross-sectional study.

Poorly managed medical waste produced at the health facilities are potential source of infections including occupational exposure to Hepatitis B Virus (HBV). This study evaluated the prevalence of HBV infection among healthcare workers (HCWs) in Kisumu County. We determined prevalence of HBV infections among 192 HCWs from nine purposively selected high-patient volume public hospitals in Kisumu County. A structured questionnaire was administered, and 4.0 ml of venous blood sample collected for Hepatitis B surface antigen (HBsAg), hepatitis B surface antibody (anti-HBs) and total hepatitis B core antibody (anti-HBc) testing using enzyme immunoassay (EIA). Of 192 HCWs sampled, 52.1% were males and the median participants age was 34.4 years with interquartile range (IQR) of 11 (28-39) years. Most participants (44%) had worked for between 1-5 years. There was low HBV vaccine uptake with 35.9% completing the required 3 doses, while 40.6% had never been vaccinated. HBV prevalence was 18.8% (36/192), prevalence of past resolved infection was 25.5% (49/192), while 37.5% (72/192) of HCW had evidence of vaccine-derived immunity and 17.7% (34/192) were susceptible. HBV prevalence among HCW who had worked for less than one year and those who had never been vaccinated was 37.5% and 35.9% respectively. Significant risk of HBV lifetime exposure was noted among HCWs with one vaccine dose, those with no known exposure, while highest in those with knowledge on HBV transmission (aOR, 7.97; 95% CI, 2.10-153.3, p-value = 0.008). HCWs who had received ≥2 doses of HBV vaccine (aOR, 0.03; 95% CI, 0.01-0.10, p-value = <0.0001) had significant HBV protection. Duration of service was not associated with HBV among HCWs. HBV prevalence was high among HCWs from nine high patient volume public hospitals in Kisumu County. Efforts to strengthen HBV vaccination uptake and dose completion are needed to reduce HBV infections among HCWs.

CD23b isoform expression in human schistosomiasis identifies a novel subset of activated B cells.

Resistance to schistosomiasis is associated with increased levels of serum parasite-specific IgE. IgE exerts its functions through its cellular receptors, FcεRI and FcεRII/CD23; however, its functional significance in humans requires further characterization. We previously reported that increased levels of CD23(+) B cells correlate with resistance to schistosomiasis in hyperexposed populations and sought to define their potential function and relationship with IgE. We found that CD23(+) B cells are a heterogeneous cell population with functional and phenotypic differences. Circulating CD23(+) B cells are uniquely activated in schistosomiasis and express the CD23b isoform and CXCR5, the homing receptor for lymphoid follicles. High CXCR5 expression by CD23(+) B cells was associated with the capacity to home to the cognate ligand CXCL13. CD23-bound IgE cross-linking increased surface expression of CXCR5, suggesting that CD23(+) B cells home directly into the lymphoid follicles upon antigen capture. As human schistosomiasis is an intravascular parasitic infection associated with a high antigenic burden in the blood, circulating CD23(+) B cells may play a role in the capture and shuttling of antigens directly to splenic follicles, highlighting a new role for circulating B cells. This function likely plays an important role in the development of protective immunity to infection with schistosomes.

Determinants of the uptake of intermittent preventive treatment of malaria in pregnancy with sulphadoxine pyrimethamine in Sabatia Sub County, Western Kenya.

BACKGROUND: Annually, 125.2 million pregnant women worldwide risk contracting malaria, including 30.3 million and 1.5 million in Sub-Saharan Africa and Kenya respectively. At least three doses of sulphadoxine pyrimethamine for intermittent preventive treatment of malaria in pregnancy (IPTp-SP) is recommended for optimal benefit. Kenya recorded low IPTp-SP optimal uptake in 2015. This study investigated the prevalence of and factors influencing IPTp-SP optimal uptake in Sabatia Sub County, Western Kenya. METHODS: A cross-sectional study was conducted in Sabatia Sub County from April to October 2020. Using a validated semi-structured questionnaire, data were obtained from 372 randomly sampled post-delivery women aged 15-49 years with live birth within one year preceding the study. Women on cotrimoxazole prophylaxis during pregnancy were excluded. Pearson Chi-square and Fisher's Exact test were measures of association used. Binary logistic regression analysed predictors of optimal IPTp-SP uptake. RESULTS: Optimal IPTp-SP uptake was 79.6%, 95% CI 75.5%-83.7%. Predictors of IPTp-SP optimization were gestational age at first antenatal care (ANC) visit (P = 0.04), frequency of ANC visits (P < 0.001), maternal knowledge of IPTp-SP benefits (P < 0.001), maternal knowledge of optimal sulphadoxine pyrimethamine (SP) dose (P = 0.03) and SP administration at ANC clinic (P = 0.03). Late ANC initiators were less likely to receive optimal IPTp-SP (aOR = 0.4, 95% CI 0.2-0.9). Odds of optimizing IPTp-SP increased among women with ≥ 4 ANC visits (aOR = 16.7, 95% CI 7.9-35.3), good knowledge of IPTp-SP benefits (aOR = 2.4, 95% CI 1.3-4.5) and good knowledge of optimal SP dose (aOR = 1.9, 95% CI 1.1-3.4). Women who never missed being administered SP were highly likely to receive optimal IPTp-SP (aOR = 2.9, 95% CI 1.1-7.2) CONCLUSIONS: This study has found high IPTp-SP optimal uptake in the study area. Efforts should be directed towards early and more frequent ANC visits. Intensive and targeted health education is required. It's fundamental to adequately stock and consistently administer SP. Future studies considering larger samples and health workers' perspectives of the health system delivery factors are recommended.

Human schistosomiasis is associated with endotoxemia and Toll-like receptor 2- and 4-bearing B cells.

Schistosomiasis is caused by parasitic trematodes. Individuals can accumulate hundreds of intravascular worms, which secrete a myriad of antigenic molecules into the bloodstream. Some of these molecules suppress immunity to microbial Toll-like receptor (TLR) ligands, such as lipopolysaccharides, which may increase host susceptibility to coinfecting pathogens. We show that schistosomiasis is associated with extremely high levels of endotoxemia as well as high mobility group 1, an endogenous inflammatory TLR ligand, in the absence of other coinfected pathogens. Circulating B cells express surface TLR2 and TLR4, reflecting systemic exposure to microbial ligands. Bacterial translocation may occur with schistosomal egg movement from the vascular to the gut and other routes, such as the skin during infection. Our report suggests that immunosuppressive schistosome antigens may have evolved to curb inflammatory responses to the high antigenic burden of translocated bacteria products and endogenous TLR ligands that arise during parasite exposure and inflammation.