Cord Blood Antiparasite Interleukin 10 as a Risk Marker for Compromised Vaccine Immunogenicity in Early Childhood.

Background: Antenatal exposure to parasites can affect infants' subsequent responses to vaccination. The present study investigated how maternal prenatal infections and newborns' antiparasite cytokine profiles relate to immunoglobulin G (IgG) responses to standard vaccination during infancy.

Methods: A total of 450 Kenyan women were tested for parasitic infections during pregnancy.

Rift Valley Fever Seroprevalence in Coastal Kenya.

Rift Valley fever virus (RVFV) causes severe disease in both animals and humans, resulting in significant economic and public health damages. The objective of this study was to measure RVFV seroprevalence in six coastal Kenyan villages between 2009 and 2011, and characterize individual-, household-, and community-level risk factors for prior RVFV exposure. Sera were tested for anti-RVFV IgG via enzyme-linked immunosorbent assay.

Divergent Effects of Exposure on Intermediate-Host Snail Species and from Coastal Kenya.

Abstract infection causes urogenital schistosomiasis, a chronic inflammatory disease that is highly prevalent in many parts of sub-Saharan Africa. Bulinid snails are the obligate intermediate hosts in the transmission of this parasite. In the present study, and snails from coastal Kenya were raised in the laboratory and exposed to miracidia derived from sympatric specimens to assess the species-specific impact of parasite contact and infection.

Dengue and West Nile Virus Transmission in Children and Adults in Coastal Kenya.

Dengue virus (DENV) and West Nile virus (WNV) are important reemerging arboviruses that are under-recognized in many parts of Africa due to lack of surveillance. As a part of a study on flavivirus, alphavirus, and parasite exposure in coastal Kenya, we measured neutralizing antibody against DENV and, to evaluate assay specificity, WNV in serum samples that tested positive for serum anti-DENV IgG by enzyme-linked immunosorbent assay. Of 830 anti-DENV IgG-positive samples that were tested for neutralizing activity, 488 (58.

Contrasting Patterns of Serologic and Functional Antibody Dynamics to Plasmodium falciparum Antigens in a Kenyan Birth Cohort.

IgG antibodies to Plasmodium falciparum are transferred from the maternal to fetal circulation during pregnancy, wane after birth, and are subsequently acquired in response to natural infection. We examined the dynamics of malaria antibody responses of 84 Kenyan infants from birth to 36 months of age by (i) serology, (ii) variant surface antigen (VSA) assay, (iii) growth inhibitory activity (GIA), and (iv) invasion inhibition assays (IIA) specific for merozoite surface protein 1 (MSP1) and sialic acid-dependent invasion pathway. Maternal antibodies in each of these four categories were detected in cord blood and decreased to their lowest level by approximately 6 months of age.

Anemia Among Children Exposed to Polyparasitism in Coastal Kenya.

Anemia represents a substantial problem for children living in areas with limited resources and significant parasite burden. We performed a cross-sectional study of 254 Kenyan preschool- and early school-age children in a setting endemic for multiple chronic parasitic infections to explore mechanisms of their anemia. Complete venous blood cell counts revealed a high prevalence of local childhood anemia (79%).

Case-Control Study of Posttreatment Regression of Urinary Tract Morbidity Among Adults in Schistosoma haematobium-Endemic Communities in Kwale County, Kenya.

Previous population-based studies have examined treatment impact on Schistosoma-associated urinary tract disease among children, but much less is known about longer-term treatment benefits for affected adult populations in areas where risk of recurrent infection is high. In communities in Msambweni, along the Kenya coast, we identified, using a portable ultrasound, 77 adults (aged 17-85) with moderate-to-severe obstructive uropathy or bladder disease due to Schistosoma haematobium. Treatment response was assessed by repeat ultrasound 1-2 years after praziquantel (PZQ) therapy and compared with interval changes among age- and sex-matched infected/treated control subjects who did not have urinary tract abnormalities at the time of initial examination.

Parasitism in Children Aged Three Years and Under: Relationship between Infection and Growth in Rural Coastal Kenya.

Background: Parasitic infections, which are among the most common infections worldwide, disproportionately affect children; however, little is known about the impact of parasitic disease on growth in very early childhood. Our objective was to document the prevalence of parasitic infections and examine their association with growth during the first three years of life among children in coastal Kenya.

Methodology/principal Findings: Children enrolled in a maternal-child cohort were tested for soil transmitted helminths (STHs: Ascaris, Trichuris, hookworm, Strongyloides), protozoa (malaria, Entamoeba histolytica and Giardia lamblia), filaria, and Schistosoma infection every six months from birth until age three years.

Factors associated with severe human Rift Valley fever in Sangailu, Garissa County, Kenya.

Background: Mosquito-borne Rift Valley fever virus (RVFV) causes acute, often severe, disease in livestock and humans. To determine the exposure factors and range of symptoms associated with human RVF, we performed a population-based cross-sectional survey in six villages across a 40 km transect in northeastern Kenya.

Methodology/principal Findings: A systematic survey of the total populations of six Northeastern Kenyan villages was performed.

Age-Stratified Profiles of Serum IL-6, IL-10, and TNF-α Cytokines Among Kenyan Children with Schistosoma haematobium, Plasmodium falciparum, and Other Chronic Parasitic Co-Infections.

In a study of children having polyparasitic infections in a Schistosoma haematobium-endemic area, we examined the hypothesis that S. haematobium-positive children, compared with S. haematobium-negative children (anti-soluble worm antigen preparation [SWAP] negative and egg negative) have increased systemic production of pro-inflammatory cytokines (interleukin [IL]-6, tumor necrosis factor [TNF]-α) and decreased down-regulatory IL-10.

Association of symptoms and severity of rift valley fever with genetic polymorphisms in human innate immune pathways.

Background: Multiple recent outbreaks of Rift Valley Fever (RVF) in Africa, Madagascar, and the Arabian Peninsula have resulted in significant morbidity, mortality, and financial loss due to related livestock epizootics. Presentation of human RVF varies from mild febrile illness to meningoencephalitis, hemorrhagic diathesis, and/or ophthalmitis with residual retinal scarring, but the determinants for severe disease are not understood. The aim of the present study was to identify human genes associated with RVF clinical disease in a high-risk population in Northeastern Province, Kenya.

High rates of o'nyong nyong and Chikungunya virus transmission in coastal Kenya.

Background: Chikungunya virus (CHIKV) and o'nyong nyong virus (ONNV) are mosquito-borne alphaviruses endemic in East Africa that cause acute febrile illness and arthritis. The objectives of this study were to measure the seroprevalence of CHIKV and ONNV in coastal Kenya and link it to demographics and other risk factors.

Methodology: Demographic and exposure questionnaires were administered to 1,848 participants recruited from two village clusters (Milalani-Nganja and Vuga) in 2009.

Effect of antenatal parasitic infections on anti-vaccine IgG levels in children: a prospective birth cohort study in Kenya.

Background: Parasitic infections are prevalent among pregnant women in sub-Saharan Africa. We investigated whether prenatal exposure to malaria and/or helminths affects the pattern of infant immune responses to standard vaccinations against Haemophilus influenzae (Hib), diphtheria (DT), hepatitis B (Hep B) and tetanus toxoid (TT).

Methods And Findings: 450 Kenyan women were tested for malaria, schistosomiasis, lymphatic filariasis (LF), and intestinal helminths during pregnancy.

Cross-sectional survey of Rift Valley fever virus exposure in Bodhei village located in a transitional coastal forest habitat in Lamu county, Kenya.

Few studies have focused on Rift Valley fever virus (RVFV) transmission in less arid, transitional landscapes surrounding known high-risk regions. The objective of this study was to identify evidence of RVFV exposure in Bodhei Village in a forested area at the edge of the RVFV-epidemic Garissa region. In a household cluster-based survey conducted between epidemics in early 2006, 211 participants were enrolled.

Cross-sectional study of the burden of vector-borne and soil-transmitted polyparasitism in rural communities of Coast Province, Kenya.

Background: In coastal Kenya, infection of human populations by a variety of parasites often results in co-infection or poly-parasitism. These parasitic infections, separately and in conjunction, are a major cause of chronic clinical and sub-clinical human disease and exert a long-term toll on economic welfare of affected populations. Risk factors for these infections are often shared and overlap in space, resulting in interrelated patterns of transmission that need to be considered at different spatial scales.

Development of a specimen-sparing multichannel bead assay to detect antiparasite IgG4 for the diagnosis of Schistosoma and Wuchereria infections on the coast of Kenya.

To better delineate the impact of parasitic coinfection in coastal Kenya, we developed a novel specimen-sparing bead assay using multiplex flow immunoassay (MFI) technology to simultaneously measure serum or plasma immunoglobulin G4 (IgG4) against Brugia malayi antigen (BMA) and Schistosoma haematobium soluble worm antigen (SWAP). Properties of the bead assay were estimated by latent class analysis using data from S. haematobium egg counts/filarial rapid diagnostic cards (RDTs), parasite-specific enzyme-linked immunosorbent assays (ELISAs), and the multichannel IgG4 assay.

Monitoring malaria vector control interventions: effectiveness of five different adult mosquito sampling methods.

Long-term success of ongoing malaria control efforts based on mosquito bed nets (long-lasting insecticidal net) and indoor residual spraying is dependent on continuous monitoring of mosquito vectors, and thus on effective mosquito sampling tools. The objective of our study was to identify the most efficient mosquito sampling tool(s) for routine vector surveillance for malaria and lymphatic filariasis transmission in coastal Kenya. We evaluated relative efficacy of five collection methods--light traps associated with a person sleeping under a net, pyrethrum spray catches, Prokopack aspirator, clay pots, and urine-baited traps--in four villages representing three ecological settings along the south coast of Kenya.

Potential for autoimmune pathogenesis of Rift Valley Fever virus retinitis.

Rift Valley Fever (RVF) is a significant threat to human health because it can progress to retinitis, encephalitis, and hemorrhagic fever. The timing of onset of Rift Valley Fever virus (RVFV) retinitis suggests an autoimmune origin. To determine whether RVFV retinitis is associated with increased levels of IgG against retinal tissue, we measured and compared levels of IgG against healthy human eye tissue by immunohistochemical analysis.

Long term study on the effect of mollusciciding with niclosamide in stream habitats on the transmission of schistosomiasis mansoni after community-based chemotherapy in Makueni District, Kenya.

Background: Schistosoma mansoni infection is a persistent public health problem in many Kenyan communities. Although praziquantel is available, re-infection after chemotherapy treatment is inevitable, especially among children. Chemotherapy followed by intermittent mollusciciding of habitats of Biomphalaria pfeifferi, the intermediate host snail, may have longer term benefits, especially if timed to coincide with natural fluctuations in snail populations.

Evaluation of the health-related quality of life of children in Schistosoma haematobium-endemic communities in Kenya: a cross-sectional study.

Background: Schistosomiasis remains a global public health challenge, with 93% of the ~237 million infections occurring in sub-Saharan Africa. Though rarely fatal, its recurring nature makes it a lifetime disorder with significant chronic health burdens. Much of its negative health impact is due to non-specific conditions such as anemia, undernutrition, pain, exercise intolerance, poor school performance, and decreased work capacity.

Physical condition and maintenance of mosquito bed nets in Kwale County, coastal Kenya.

Background: Despite the extensive ownership and use of insecticide-treated nets (ITNs) over the last decade, the effective lifespan of these nets, especially their physical integrity, under true operational conditions is not well-understood. Usefulness of nets declines primarily due to physical damage or loss of insecticidal activity.

Methods: A community based cross-sectional survey was used to determine the physical condition and to identify predictors of poor physical condition for bed nets owned by individuals from communities in Kwale County, coastal Kenya.

Impact of polyparasitic infections on anemia and undernutrition among Kenyan children living in a Schistosoma haematobium-endemic area.

We measured prevalence of Schistosoma haematobium, Wuchereria bancrofti, Plasmodium falciparum, hookworm, and other geohelminths among school-aged children in four endemic villages in Kwale County, Kenya and explored the relationship between multiparasite burden, undernutrition, and anemia. In 2009-2010 surveys, cross-sectional data were obtained for 2,030 children 5-18 years old. Infections were most prevalent for S.

Evaluation of loop-mediated isothermal amplification suitable for molecular monitoring of schistosome-infected snails in field laboratories.

We previously described loop-mediated isothermal amplification (LAMP) for detection of Schistosoma haematobium and S. mansoni DNA in infected snails. In the present study, we adapted the LAMP assay for application in field laboratories in schistosomiasis-endemic areas.

Projecting the long-term impact of school- or community-based mass-treatment interventions for control of Schistosoma infection.

Background: Schistosomiasis remains a significant health burden in many areas of the world. Morbidity control, focused on limiting infection intensity through periodic delivery of anti-schistosomal medicines, is the thrust of current World Health Organization guidelines (2006) for reduction of Schistosoma-related disease. A new appreciation of the lifetime impact of repeated Schistosoma infection has directed attention toward strategies for greater suppression of parasite infection per se, with the goal of transmission interruption.

Birthweight in offspring of mothers with high prevalence of helminth and malaria infection in coastal Kenya.

Results of studies on the associations of maternal helminth infection and malaria-helminth co-infection on birth outcomes have been mixed. A group of 696 pregnant women from the Kwale district in Kenya were recruited and tested for malaria and helminth infection at delivery. Birthweight was documented for 664 infants.