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Introduction: Globally, poor sanitation is the cause of childhood diseases. Annually, more than 19,500 people die from diarrhea of which 17,100 are children. Diarrhea, which accounts for 16% of deaths among the children below 5 years, is highly linked to open defecation (OD). Poor excreta disposal remains a major challenge to improved sanitation and hygiene in many communities of Kenya and therefore they continue to practice open defecation. Construction and utilization of a latrine at home is a protective factor for communicable diseases. About 52% of the population practice proper utilization of latrine in low-income countries. Improper utilization of latrines leads to the contamination of the water sources. Availability of a pit latrine does not guarantee utilization because other factors like functionality and distance influence its use. Furthermore, the availability and use of the latrine depends on maintenance practices of the latrines and cleanliness as well as the quality of housing and household compound. Aims: To analyze the physical and social demographic factors influencing the utilization of pit latrines in Tigania East Sub-County, Meru County, Kenya. Study Design: The study was a descriptive cross-sectional survey. Place and Duration of Study: The study was carried out in Tigania East Sub-County, Meru County, Kenya shown in Fig. 3. Household survey was carried out between June 2018 and December 2019. Methodology: This was a descriptive cross-sectional survey involving 369 respondents selected by systematic random sampling from different households across the sub-county was utilized. Data collection was done using a structured questionnaire administered in English and a spot observation checklist. All data generated was entered, validated and analyzed using SPSS using SPSS Software Version 23. Descriptive analysis was done during the calculation of measures of central tendency and proportions. Regression analysis was used in the determination of any association between the socio-demographic factors and the utilization of latrines. Results: Ownership, location and functionality of the pit latrine were positively associated with utilization (OR=2.127, OR=1.53, OR=4.36, P=.00). Households that owned pit latrines were 2 times likely to utilize the pit latrines than those without a pit latrine. Moreover, household size, gender, and employment were positively related to utilization (R=0.502, P=.00). High construction costs challenges were 7 times linked to open defecation practices. Households with less than 6 members were 2.35 times more likely to utilize the pit latrine compared to those with 7-12 members (OR=2.35, X²=13.573, P=.00). Conclusion: Interventions should target households with more than 7 members. A call for partnerships between government and donors to improve household income, water sources, and sanitation practices in Tigania East Sub-County is necessary. A call for funding projects related to pour-flush pit latrines and wet technologies to enhance utilization.

Effective conservation and management of wildlife in the current changing world, call for incorporation of infectious zoonotic diseases surveillance systems, among other interventions. One of such diseases is echinococcosis, a zoonotic disease caused by Echinococcus species. This disease exists in two distinct life cycle patterns, the domestic and wildlife cycles. To investigate possible inter-links between these cycles in Kenya, 729 fecal samples from wild carnivores and 406 from domestic dogs (Canis lupus familiaris) collected from Maasai Mara and Samburu National Reserves were analyzed. Taeniid eggs were isolated by zinc chloride sieving-flotation method and subjected to polymerase chain reaction of nicotinamide adenine dehydrogenase subunit 1 (NAD1). Subsequent amplicons were sequenced, edited and analyzed with GENtle VI.94 program. The samples were further subjected to molecular identification of specific host species origin. All sequences obtained were compared with those in Gene-bank using Basic Local Alignment Search Tool (BLAST). The study found that there were 74 taeniid positive samples, 53 from wild carnivores and 21 from domestic dogs. In wildlife, mixed infections with Echinococcus and Taenia species were identified and these included E. granulosus sensu stricto, E. felidis, T. canadensis G6/7, Taenia hydatigena, T. multiceps, and T. saginata. Domestic dogs harbored Echinococcus and Taenia species similar to wild carnivores including E. granulosus G1–3, E. felidis, T. multiceps, T. hydatigena, and T. madoquae. Taenia species of nine taeniid eggs were not identified. Majority of genotypes were found in hyena (Crocuta crocuta) fecal samples. Distribution of Echinococcus and Taenia spp. varied with hosts. Mixed infections of Echinococcus spp, T. multiceps and T. hydatigena in a single animal were common. There seemed to be existence of interactions between the two cycles, although public health consequences are unknown. The presence of T. saginata in hyena suggests scavenging of human fecal matter by the animal. In addition, presence of T. multiceps, T hydatigena, T madoquae and T. saginata in the two cycles suggested possible human exposure to these parasites. The results are important in drawing up of strategies and policies towards prevention and control of Echinococcosis and other Taenia related parasitic infections, especially in endemic areas given their potential risk to public and socio- economic livelihood.

The epidemiology of vaccine preventable diseases has been modified by use and implementation of various vaccination programs in many countries. However, because of observed suboptimal vaccination rates, debate has emerged on the benefits of such vaccines worldwide. Maternal and childhood vaccinations have been evaluated and found extremely effective at preventing illness in pregnant women and new-borns despite low uptake of such vaccines in many areas. The objective of this study was to determine the Vaccination Coverage and factors that influence uptake of newly introduced vaccines among children aged less than 23 months in Laikipia North Sub-County. The study used multistage sampled parents and guardians of children below 23 months of age but residents of Laikipia North Sub-County within Laikipia County. Trained interviewers visited sampled households and administered a standardized pretested questionnaire. Mothers and guardians were interviewed and asked to show the interviewers Mother-Child Post Natal Booklets for the study enrolled children. Key informant questionnaires were also administered to Health facility staff. Data entry and analysis were performed using SPSS and Microsoft Excel. Chi-Square for Proportion and Student T-test were used to assess factors influencing uptake of vaccines in the sub-county. The study found that slightly above half (59%) of the care givers indicated that their child had been vaccinated. Majority (61%) of the care givers had their children given rotavirus vaccine while an equal number (61%) had their children given Pneumococcal vaccine. 52% of the care givers indicated that their children were given IPV (Inactivated Polio Vaccine). 53% of the children who were given rotavirus vaccine received the required 2 doses. Among social-cultural factors, the need for permission from mother-in-law (p = 0.003), belief that vaccination makes girls infertile (p = 0.046) and belief that vaccination at a very young age can harm the child (p = 0.021). Migration with animals or nomadic lifestyle (p = 0.033) and the need for permission from my husband to have Child Immunized (p = 0.038) were significantly related to uptake of vaccination among the care givers. Occupation of the care giver (p = 0.044), the breadwinner in the family (p = 0.025) and the means of transport used to go to the facility (p = 0.007) and average household income (p = 0.033) were also significantly related to uptake of vaccination. None of the health system factors under investigation was found to significantly relate to uptake of vaccination. The study finding indicates that low uptake of vaccination was due to social cultural and social economic factors and recommends that Health education campaigns on the need of vaccination should target all members of the population. It further recommends that poverty eradication measures should be stepped up in the study area.

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. Serologic antibodies to 3 preerythrocytic and 10 blood-stage antigens subsequently increased, reaching peak prevalence by 36 months. In contrast, antibodies measured by VSA, GIA, and IIA remained low even up to 36 months. Infants sensitized to P. falciparum in utero , defined by cord blood lymphocyte recall responses to malaria antigens, acquired antimalarial antibodies at the same rate as those who were not sensitized in utero , indicating that fetal exposure to malaria antigens did not affect subsequent infant antimalarial responses. Infants with detectable serologic antibodies at 12 months of age had an increased risk of P. falciparum infection during the subsequent 24 months. We conclude that serologic measures of antimalarial antibodies in children 36 months of age or younger represent biomarkers of malaria exposure rather than protection and that functional antibodies develop after 36 months of age in this population.

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. Overall seroprevalence for anti-RVFV was high (18%) and comparable with rates in the more arid, dense brush regions farther north. Seroprevalence of adults was 28%, whereas that of children was significantly lower (3%; P < 0.001); the youngest positive child was age 3 years. Males were more likely to be seropositive than females (25% versus 11%; P < 0.01), and animal husbandry activities (birthing, sheltering, and butchering) were strongly associated with seropositivity. The results confirm that significant RVFV transmission occurs outside of recognized high-risk areas and independent of known epidemic periods.

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. Overall, 51 (1.8%; confidence interval [CI95] 1.3-2.3) of 2,871 samples were seropositive for RVFV. Seroprevalence differed significantly among villages, and was highest in Jego Village (18/300; 6.0%; CI95 3.6-9.3) and lowest in Magodzoni (0/248). Adults were more likely to be seropositive than children (P < 0.001). Seropositive subjects were less likely to own land or a motor vehicle (P < 0.01), suggesting exposure is associated with lower socioeconomic standing (P = 0.03). RVFV exposure appears to be low in coastal Kenya, although with some variability among villages.

Schistosoma haematobium 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, Bulinus globosus and Bulinus nasutus snails from coastal Kenya were raised in the laboratory and exposed to miracidia derived from sympatric S. haematobium specimens to assess the species‐specific impact of parasite contact and infection. The snails’ subsequent patterns of survival, cercarial shedding, and reproduction were monitored for up to 3 months postexposure. Schistosoma haematobium exposure significantly decreased the survival of B. globosus, but not of B. nasutus. Although both species were capable of transmitting S. haematobium, the B. globosus study population had a greater cumulative incidence of cercarial shedders and a higher average number of cercariae shed per snail than did the B. nasutus population. The effects of prior parasite exposure on snail reproduction were different between the two species. These included more numerous production of egg masses by exposed B. nasutus (as compared with unexposed snails), contrasted to decreased overall egg mass production by parasite‐exposed B. globosus. The interspecies differences in the response to and transmission of S. haematobium reflect clear differences in life histories for the two bulinid species when they interact with the parasite, which should be taken into account when planning control interventions aimed at reducing each host snails’ contribution to local transmission of Schistosoma infection.

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. A total of 42.7% of the mothers were infected with Plasmodium falciparum, 30.6% with Schistosoma haematobium, 36.2% with filariasis, 31.5% with hookworm, and 5.9% with Trichuris trichiura; co-infection was present in 46.7%. Low birthweight (LBW) (weight < 2,500 grams) was present in 15.4% of the offspring, and 8.3% had a weight z-score ≤ 2 SD below the World Health Organization mean. Only gravida, age, and locale had a significant association with LBW. The high prevalence of maternal infection coupled with a higher than expected percentage of LBW highlight a need for further investigation of the association of maternal co-infection with LBW.

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 (58.8%) neutralized DENV and 94 (11.3%) neutralized WNV. Of children ≤ 10 years of age, 23% and 17% had serum neutralizing antibody to DENV and WNV, respectively, indicating that DENV and WNV transmission has occurred in this region within the past decade. The results suggest that ongoing DENV and WNV transmission continues on the coast of Kenya and supports a need for routine arboviral surveillance in the area to detect and respond to future outbreaks.

We analyzed temporal changes in spatial patterns of active Schistosoma haematobium infection in different age groups and associated them with ponds infested with Bulinus snails. A major drought between 2001 and 2009 resulted in drying of ponds that were known sources of infection, and we detected very few or no snails in ponds that were infested in the past. The household-level spatial pattern of infection for children of various age groups in 2009 was contrasted with historical data from 2000. The significant local clustering of high- and low-infection levels among school-aged children that occurred in 2000 was absent in 2009. We attribute the disappearance of significant clustering around historical transmission hot spots to a decade-long drought in our study area. The implications of extreme weather and climate conditions on risk and transmission of S. haematobium and their relevance to control strategies are discussed. Copyright © 2011 by The American Society of Tropical Medicine and Hygiene.

In malaria endemic regions, a fetus is often exposed in utero to Plasmodium falciparum blood-stage Ags. In some newborns, this can result in the induction of immune suppression. We have previously shown these modulated immune responses to persist postnatally, with a subsequent increase in a child’s susceptibility to infection. To test the hypothesis that this immune suppression is partially mediated by malaria-specific regulatory T cells (Tregs) in utero, cord blood mononuclear cells (CBMC) were obtained from 44 Kenyan newborns of women with and without malaria at delivery. CD4+CD25lo T cells and CD4+CD25hi FOXP3+ cells (Tregs) were enriched from CBMC. Treg frequency and HLA-DR expression on Tregs were significantly greater for Kenyan as compared with North American CBMC (p < 0.01). CBMC/CD4+ T cells cultured with P. falciparum blood-stage Ags induced production of IFN-γ, IL-13, IL-10, and/or IL-5 in 50% of samples. Partial depletion of CD25hi cells augmented the Ag-driven IFN-γ production in 69% of subjects with malaria-specific responses and revealed additional Ag-reactive lymphocytes in previously unresponsive individuals (n = 3). Addition of Tregs to CD4+CD25lo cells suppressed spontaneous and malaria Ag-driven production of IFN-γ in a dose-dependent fashion, until production was completely inhibited in most subjects. In contrast, Tregs only partially suppressed malaria-induced Th2 cytokines. IL-10 or TGF-β did not mediate this suppression. Thus, prenatal exposure to malaria blood-stage Ags induces Tregs that primarily suppress Th1-type recall responses to P. falciparum blood-stage Ags. Persistence of these Tregs postnatally could modify a child’s susceptibility to malaria infection and disease.

Few studies have investigated the many mosquito species that harbor arboviruses in Kenya. During the 2006–2007 Rift Valley fever outbreak in North Eastern Province, Kenya, exophilic mosquitoes were collected from homesteads within 2 affected areas: Gumarey (rural) and Sogan-Godud (urban). Mosquitoes (n = 920) were pooled by trap location and tested for Rift Valley fever virus and West Nile virus. The most common mosquitoes trapped belonged to the genus Culex (75%). Of 105 mosquito pools tested, 22% were positive for Rift Valley fever virus, 18% were positive for West Nile virus, and 3% were positive for both. Estimated mosquito minimum infection rates did not differ between locations. Our data demonstrate the local abundance of mosquitoes that could propagate arboviral infections in Kenya and the high prevalence of vector arbovirus positivity during a Rift Valley fever outbreak.

Mother-to-child-transmission (MTCT) of human immunodeficiency virus (HIV) remains a significant cause of new HIV infections in many countries. To examine whether fetal immune activation as a consequence of prenatal exposure to parasitic antigens increases the risk of MTCT, cord blood mononuclear cells (CBMCs) from Kenyan and North American newborns were examined for relative susceptibility to HIV infection in vitro. Kenyan CBMCs were 3-fold more likely to be infected with HIV than were North American CBMCs (P=.03). Kenyan CBMCs with recall responses to malaria antigens demonstrated enhanced susceptibility to HIV when compared with Kenyan CBMCs lacking recall responses to malaria (P=.03). CD4(+) T cells from malaria-sensitized newborns expressed higher levels of CD25 and human leukocyte antigen DR ex vivo, which is consistent with increased immune activation. CD4(+) T cells were the primary reservoir of infection at day 4 after virus exposure. Thus, prenatal exposure and in utero priming to malaria may increase the risk of MTCT.

In sub-Saharan Africa, chronic hepatosplenomegaly, with palpable firm/hard organ consistency, is common, particularly among school-aged children. This morbidity can be caused by long-term exposure to malaria, or by Schistosoma mansoni, and it is exacerbated when these two occur together. Although immunological mechanisms probably underlie the pathogenic process, these mechanisms have not been identified, nor is it known whether the two parasites augment the same mechanisms or induce unrelated processes that nonetheless have additive or synergistic effects. Kenyan primary schoolchildren, living in a malaria/schistosomiasis co-transmission area, participated in cross-sectional parasitological and clinical studies in which circulating immune modulator levels were also measured. Plasma IL-12p70, sTNF-RII, IL-10 and IL-13 levels correlated with relative exposure to malaria, and with hepatosplenomegaly. Soluble-TNF-RII and IL-10 were higher in children infected with S. mansoni. Hepatosplenomegaly caused by chronic exposure to malaria was clearly associated with increased circulating levels of pro-inflammatory mediators, with higher levels of regulatory modulators, and with tissue repair cytokines, perhaps being required to control the inflammatory response. The higher levels of regulatory modulators amongst S. mansoni infected children, compared to those without detectable S. mansoni and malarial infections, but exposed to malaria, suggest that S. mansoni infection may augment the underlying inflammatory reaction.

Cord blood T cells have been reported to respond to a variety of exogenous Ags, including environmental allergens and various viruses and parasites, as demonstrated by enhanced proliferation and cytokine secretion. This finding is evidence that Ags in the maternal environment transplacentally prime and result in fetal development of memory T cells. Some studies suggest these neonatal T cell responses may arise by nonspecific activation of T cells that express TCRs with low binding affinity, thus lacking fine lymphocyte specificity. To address this question, we examined malaria Ag stimulation of human cord and adult blood mononuclear cells in samples from residents of a malaria endemic area in Kenya. We constructed overlapping 18-mer peptides derived from sequences contained in dimorphic alleles of the C-terminal 33-kDa fragment of Plasmodium falciparum merozoite protein 1. This study identified a dominant T cell epitope for one MSP133 allele (MAD20) and two T cell epitopes for the second allele (K1); these epitopes were nonoverlapping and allele specific. In a given donor, peptide-specific proliferation and IFN-γ secretion were highly concordant. However, IL-10 and IL-13 secretion were not correlated. Importantly, the fine specificity of lymphocyte proliferation and cytokine secretion in cord and adult blood mononuclear cells was similar. Cord blood cells obtained from malaria-infected pregnant women were 4-fold more likely to acquire a peptide-specific immune response. We conclude that the fetal malaria response functions in a fully adaptive manner and that this response may serve to help protect the infant from severe malaria during infancy.

OBJECTIVES Chronic exposure to malaria exacerbates Schistosoma mansoni-associated hepatosplenomegaly in school-aged children. However, residual hepatosplenomegaly after treatment of S. mansoni with concurrent mollusciciding suggests malaria could be an underlying cause of hepatosplenomegaly. We investigated the role of chronic malaria in childhood hepatosplenomegaly in the presence and absence of concurrent S. mansoni infection. METHODS Cross-sectional study of children in an study area where transmission of S. mansoni, but not malaria, is restricted to the eastern end. Clinical and ultrasound examinations were conducted, and parasitological and serological tests used to determine S. mansoni infection intensities and comparative exposure levels to malaria. RESULTS Chronic exposure to malaria, as determined by Pfs-IgG3 levels, was associated with hepatosplenomegaly even in the absence of S. mansoni infection. Children infected with S. mansoni mostly had light to moderate infection intensities but greater enlargement of the liver and spleen than children who did not have schistosomiasis, and for the left liver lobe this was S. mansoni infection intensity dependent. CONCLUSIONS Children chronically exposed to malaria but without S. mansoni infection can have hepatosplenomegaly, which even light S. mansoni infections can exacerbate in an intensity-dependent manner. Thus, concurrent chronic exposure to S. mansoni and Plasmodium falciparum can have an additive or synergistic effect on childhood morbidity.

Schistosoma haematobium infects nearly 150 million people, primarily in Africa, and is transmitted by select species of local bulinid snails. These snails can host other related trematode species as well, so that effective detection and monitoring of snails infected with S. haematobium requires a successful differentiation between S. haematobium and any closely related schistosome species. To enable differential detection of S. haematobium DNA by simple polymerase chain reaction (PCR), we designed and tested primer pairs from numerous newly identified Schistosoma DNA repeat sequences. However, all pairs tested were found unsuitable for this purpose. Differentiation of S. haematobium from S. bovis, S. mattheei, S. curassoni, and S. intercalatum (but not from S. margrebowiei) was ultimately accomplished by PCR using one primer from a newly identified repeat, Sh110, and a second primer from a known schistosomal splice-leader sequence. For evaluation of residual S. haematobium transmission after control interventions, this differentiation tool will enable accurate monitoring of infected snails in areas where S. haematobium is sympatric with the most prevalent other schistosome species.

Rift Valley fever virus (RVFV) is an emerging pathogen that maintains high biodefense priority based on its threat to livestock, its ability to cause human hemorrhagic fever, and its potential for aerosol spread. To define the range of human transmission during inter-epidemic and epidemic periods in Kenya, we tested archived sera from defined populations (N = 1,263) for anti-RVFV IgG by ELISA and plaque reduction neutralization testing. RVFV seroprevalence was 10.8% overall and varied significantly by location, sex, and age. In NW Kenya, high seroprevalence among those born before 1980 indicates that an undetected epidemic may have occurred then. Seroconversion documented in highland areas suggests previously unsuspected inter-epidemic transmission. RVFV seroprevalence is strikingly high in certain Kenyan areas, suggesting endemic transmission patterns that may preclude accurate estimation of regional acute outbreak incidence. The extent of both epidemic and inter-epidemic RVFV transmission in Kenya is greater than previously documented.

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%). Evaluating the potential links between low hemoglobin and socioeconomic factors, nutritional status, hemoglobinopathy, and/or parasite infection, we identified age < 9 years (odds ratio [OR]: 12.0, 95% confidence interval [CI]: 4.4, 33) and the presence of asymptomatic malaria infection (OR: 6.8, 95% CI: 2.1, 22) as the strongest independent correlates of having anemia. A total of 130/155 (84%) of anemic children with iron studies had evidence of iron-deficiency anemia (IDA), 16% had non-IDA; 50/52 of additionally tested anemic children met soluble transferrin-receptor (sTfR) criteria for combined anemia of inflammation (AI) with IDA. Children in the youngest age group had the greatest odds of iron deficiency (OR: 10.0, 95% CI: 3.9, 26). Although older children aged 9-11 years had less anemia, they had more detectable malaria, Schistosoma infection, hookworm, and proportionately more non-IDA. Anemia in this setting appears multifactorial such that chronic inflammation and iron deficiency need to be addressed together as part of integrated management of childhood anemia.

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. A total of 804 children, 2-19 years of age, were surveyed between July and December 2009 and tested for S. haematobium, Plasmodium falciparum, filariasis, and soil-transmitted helminth infections. Plasma levels of IL-6, TNF-α, and IL-10 were compared for S. haematobium-positive and S. haematobium-negative children, adjusting for malaria, filaria, and hookworm co-infections, and for nutritional status, age group, sex, and geographic location. IL-10 was significantly elevated among children infected with S. haematobium, showing bimodal peaks in 7-8 and 13-14 years age groups. IL-10 was also higher among children who were acutely malnourished, whereas IL-10 levels were lower in the presence of S. haematobium-filaria co-infection. After adjustment for co-factors, IL-6 was significantly elevated among children of 5-6 years and among those with P. falciparum infection. Lower levels of IL-6 were found in malaria-hookworm co-infection. High levels of TNF-α were found in children aged 11-12 years regardless of infection status. In addition, village of residence was a strong predictor of IL-6 and IL-10 plasma levels. In adolescent children infected with S. haematobium, there is an associated elevation in circulating IL-10 that may reduce the risk of later morbidity. Although we did not find a direct link between S. haematobium infection and circulating pro-inflammatory IL-6 and TNF-α levels, future T-cell stimulation studies may provide more conclusive linkages between infection and cytokine responses in settings that are endemic for multiple parasites and multiple co-infections.

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. Anthropometrics were measured at each visit. We used generalized estimating equation (GEE) models to examine the relationship between parasitic infections experienced in the first three years of life and growth outcomes (weight, length and head circumference). Of 545 children, STHs were the most common infection with 106 infections (19%) by age three years. Malaria followed in period prevalence with 68 infections (12%) by three years of age. Filaria and Schistosoma infection occurred in 26 (4.8%) and 16 (2.9%) children, respectively. Seven percent were infected with multiple parasites by three years of age. Each infection type (when all STHs were combined) was documented by six months of age. Decreases in growth of weight, length and head circumference during the first 36 months of life were associated with hookworm, Ascaris, E. histolytica, malaria and Schistosoma infection. In a subset analysis of 180 children who followed up at every visit through 24 months, infection with any parasite was associated with decelerations in weight, length and head circumference growth velocity. Multiple infections were associated with greater impairment of linear growth. Conclusions/Significance Our results demonstrate an under-recognized burden of parasitism in the first three years of childhood in rural Kenya. Parasitic infection and polyparasitism were common, and were associated with a range of significant growth impairment in terms of weight, length and/or head circumference., Author Summary Parasitic infections are extremely common worldwide and children are especially vulnerable to these infections during critical periods of growth and development. There is a paucity of information about how frequently very young children (under the age of five years) are infected with parasites and the effects of parasitic infections on their growth and development. The findings from this study reveal that not only does infection occur early in life; it is associated with decreases in physical growth, even with low overall prevalence for some parasites. Decreases in growth of weight, length and head circumference during the first 36 months of life were associated with hookworm, Ascaris, E. histolytica, malaria and Schistosoma infection. In a subset analysis of 180 children who followed up at every visit through 24 months, infection with any parasite was associated with decelerations in weight, length and head circumference growth velocity. Multiple infections were associated with greater impairment of linear growth. It seems worthwhile to pursue a better understanding of prevalence and effects of parasitic infection in this vulnerable group to effectively target therapeutic interventions. And finally, if parasite transmission is to be significantly disrupted, control programs targeting these young, usually asymptomatic, age groups may be critical.

As part of an extensive study of the eco-epidemiology of urinary schistosomiasis along the southern coast of Kenya, spatial and temporal transmission patterns were associated with various ponds infested with Bulinus snails. The household-level spatial pattern of infection for children of various age groups in 2000 was contrasted with historical data from 1984. Significant local clustering of high and low infection levels among school age children was detected, and the spatial extent of clusters and their direction from specific water sources were measured. High infection levels were clustered around ponds known to contain Bulinus nasutus snails that shed Schistosoma haematobium cercariae, and low infection levels were concentrated near a river where intermediate host snails were rarely found. The spatial patterns of infection varied between 2000 and 1984 and between age groups. High levels of infection were clustered around different transmission foci in the two study periods, and, for younger children in 2000, were clustered nearer to the transmission foci than for the older children. Simultaneous consideration of the effects of different foci on transmission will allow for targeted application of control measures aimed at interrupting S. haematobium transmission at a local level.

Late benefits of remote antischistosomal therapy were estimated among long-term residents of an area with high transmission of Schistosoma haematobium (Msambweni, Kenya) by comparing infection and disease prevalence in two local adult cohorts. We compared 132 formerly treated adults (given treatment in childhood or adolescence > or = 10 years previously) compared with 132 age- and sex-matched adults from the same villages who had not received prior treatment. The prevalence of current infection, hematuria, and ultrasound bladder abnormalities were significantly lower among the previously treated group, who were found to be free of severe bladder disease. Nevertheless, heavy infection was equally prevalent (2-3%) in both study groups, and present rates of hydronephrosis were not significantly different. Therapy given in childhood or adolescence appears to improve risk for some but not all manifestations of S. haematobium infection in later adult life. Future prospective studies of continued treatment into adulthood will better define means to obtain optimal, community-based control of S. haematobium-related disease in high-risk locations.

Real-time quantitative PCR (RTQ-PCR) provides a quick, accurate, and reproducible quantification of parasites. However, the value of RTQ-PCR for predicting clinical outcomes of malaria is unknown. Here, we compared RTQ-PCR to microscopy of blood smears, nested PCR (nPCR), and parasite circulating-antigen (CAg) assays for detection of Plasmodium falciparum in pregnant Kenyan women and their infants and related these findings to parity and birth weights in their newborns ( n = 554). nPCR was the most sensitive assay for detection of malaria in pregnancy, followed in decreasing order of sensitivity by RTQ-PCR, CAg assays, and blood smears. RTQ-PCR detected a higher frequency of malaria infection (46%) in maternal peripheral blood in primiparous than in multiparous women (35%; P < 0.001), with a >12-fold difference in parasite burden (geometric mean = 25,870 versus 2,143 amplicons/μl blood; P < 0.0001). Similarly, the presence of placental malaria determined by RTQ-PCR was approximately twofold higher in primiparous versus multiparous women (21% versus 13%; P < 0.01). The presence and intensity of malaria infection in pregnant women estimated by RTQ-PCR strongly correlated with low-birth-weight babies, especially in those with high amplicon numbers. RTQ-PCR identified malaria-infected women, missed by blood smear, who were at risk for having underweight offspring. By contrast, malaria detected by nPCR and CAg assay showed a much weaker association with parity or low birth weight. Thus, RTQ-PCR provides an estimate of parasite burden that is more sensitive than blood smear and is predictive of clinical outcomes of malaria infection in pregnant women and newborns.

Prenatal immunity toPlasmodium falciparummerozoite proteins involved in erythrocyte invasion may contribute to the partial protection against malaria that is acquired during infancy in areas of stable malaria transmission. We examined newborn and maternal cytokine and antibody responses to merozoite surface protein-1 (MSP-1), ribosomal phosphoprotein P0 (PfP0), and region II of erythrocyte binding antigen-175 (EBA-175) in infant-mother pairs in Kenya. Overall, 82 of 167 (50%), 106 of 176 (60%), and 38 of 84 (45%) cord blood lymphocytes (CBL) from newborns produced one or more cytokines in response to MSP-1, PfP0, and EBA-175, respectively. Newborns of primigravid and/or malaria-infected women were more likely to have antigen-responsive CBL than were newborns of multigravid and/or uninfected women at delivery. Newborn cytokine responses did not match those of their mothers and fell into three distinct categories, Th1 (21 of 55 CBL donors produced only gamma interferon and/or interleukin 2 [IL-2]), Th2 (21 of 55 produced only IL-5 and/or IL-13), and mixed Th1/Th2 (13 of 55). Newborns produced more IL-10 than adults. High and low levels of cord blood IL-12 p70 production induced by anti-CD40 activation were associated with malaria-specific Th1 and Th2 responses, respectively. Antigen-responsive CBL in some newborns were detected only after depletion of IL-10-secreting CD8 cells with enrichment for CD4 cells. These data indicate that prenatal sensitization to blood-stagePlasmodium falciparumoccurs frequently in areas where malaria is holoendemic. Modulation of this immunity, possibly by maternal parity and malaria, may affect the acquisition of protective immunity against malaria during infancy.

Bladder and kidney disease, which affect approximately 25%-30% of subjects infected with Schistosoma haematobium, are mediated by T cell-dependent granulomatous responses to schistosome eggs. To determine why only some infected subjects develop disease, we examined the hypothesis that infected Kenyan subjects with ultrasound-detected urinary-tract morbidity (n=49) had dysregulated cytokine production leading to enhanced granulomatous responses, compared with subjects of similar age and intensity of infection without morbidity (n=100). Peripheral blood mononuclear cells from subjects with morbidity produced 8-fold greater levels of egg antigen-driven tumor necrosis factor (TNF)-alpha and had a 99-fold greater mean TNF-alpha:interleukin (IL)-10 ratio, compared with subjects without disease. No differences in cytokine response to non-egg-derived schistosome antigens were observed between groups. Subjects with morbidity had increased TNF-alpha production in response to endotoxin, suggesting an innate hyperresponsiveness. These results indicate that increased TNF-alpha production, relative to that of IL-10, is associated with developing bladder-wall morbidity with S. haematobium infection.

OBJECTIVE To establish the prevalence of congenital urinary tract abnormalities in a full population-based ultrasound survey of an area of coastal Kenya. METHODS Ultrasound examination of 3118 residents of 912 households, including all available subjects over 2 years of age, residing in five contiguous rural villages 50 km south of Mombasa. RESULTS Survey findings indicated simple renal ectopia in 11 of 3118 subjects (0.35%) and renal agenesis in three (0.096%). No cases of horseshoe kidney or complex urinary anomaly were detected, and no cases of multiple congenital anomaly were found. Ectopia cases were evenly distributed between men and women, and across the five study villages. None of the individuals affected by renal ectopia were closely related (i.e.

Urinary schistosomiasis remains a major contributor to the disease burden along the southern coast of Kenya. Selective identification of transmission hot spots offers the potential for more effective, highly-focal snail control and human chemotherapy to reduce Schistosoma haematobium transmission. In the present study, a geographic information system was used to integrate demographic, parasitologic, and household location data for an endemic village and neighboring households with the biotic, abiotic, and location data for snail collection/water contact sites. A global spatial statistic was used to detect area-wide trends of clustering for human infection at the household level. Local spatial statistics were then applied to detect specific household clusters of infection, and, as a focal spatial statistic, to evaluate clustering of infection around a putative transmission site. High infection intensities were clustered significantly around a water contact site with high numbers of snails shedding S. haematobium cercariae. When age was considered, clustering was found to be significant at different distances for different age groups.

To estimate their heritable component of risk for Schistosoma haematobium infection intensity and disease, we performed a community-based family study among an endemic population in coastal Kenya. Demography and family linkages were defined by house-to-house interviews, and infection prevalence and disease severity were assessed by standard parasitologic testing and by ultrasound. The total population was 4,408 among 912 households, with 241 identified pedigree-household groups. Although age- and sex-adjusted risk for greater infection intensity was clustered within households (odds ratio = 2.7), analysis of extended pedigree-household groups indicated a relatively low heritability score for this trait (h2 = 0.199), particularly after adjustment for common household exposure effects (adjusted h2 = 0.086). Statistical evidence was slightly stronger (h2 = 0.353) for familial clustering of bladder morbidity, with an adjusted h2 = 0.142 after accounting for household exposure factors. We conclude that among long-established populations of coastal Kenya, heritable variation in host susceptibility is low, and likely plays a minimal role in determining individual risk for infection or disease.

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. Of the 77 affected adults, 62 (81%) had improvement in bladder and/or kidney scores after treatment, 14 (18%) had no change, and one (1.3%) had progression of disease. Of the 77 controls, 75 (97%) remained disease free by ultrasound, while two (3%) had apparent progression with abnormal findings on follow-up examination. We conclude that PZQ therapy for S. haematobium is effective in significantly reducing urinary tract morbidity from urogenital schistosomiasis among adult age groups, and affected adults stand to benefit from inclusion in mass treatment campaigns.

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. After three standard vaccinations at 6, 10 and 14 weeks, their newborns were followed biannually to age 36 months and tested for absolute levels of IgG against Hib, DT, Hep B, and TT at each time point. Newborns’ cord blood (CB) lymphocyte responses to malaria blood-stage antigens, soluble Schistosoma haematobium worm antigen (SWAP), and filaria antigen (BMA) were also assessed. Three immunophenotype categories were compared: i) tolerant (those having Plasmodium-, Schistosoma-, or Wuchereria-infected mothers but lacking respective Th1/Th2-type recall responses at birth to malaria antigens, SWAP, or BMA); ii) sensitized (those with infected/uninfected mothers and detectable Th1/Th2-type CB recall response to respective parasite antigen); or iii) unexposed (no evidence of maternal infection or CB recall response). Overall, 78.9% of mothers were infected with LF (44.7%), schistosomiasis (32.4%), malaria (27.6%) or hookworm (33.8%). Antenatal maternal malaria, LF, and hookworm were independently associated with significantly lower Hib-specific IgG. Presence of multiple maternal infections was associated with lower infant IgG levels against Hib and DT antigens post-vaccination. Post-vaccination IgG levels were also significantly associated with immunophenotype: malaria-tolerized infants had reduced response to DT, whereas filaria-tolerized infants showed reduced response to Hib. Conclusions There is an impaired ability to develop IgG antibody responses to key protective antigens of Hib and diphtheria in infants of mothers infected with malaria and/or helminths during pregnancy. These findings highlight the importance of control and prevention of parasitic infections among pregnant women., Author Summary Parasitic infections are prevalent among pregnant women in sub-Saharan Africa. Prenatal exposure to parasitic infections can generate several potential effects on fetal immune responses and affect functional antibody generation during subsequent vaccination. There is a paucity of data on the detrimental effects of chronic parasitic infections during pregnancy on the response to vaccine from birth to childhood. This paper highlights the overwhelming presence of helminth infection and malaria in pregnant women in rural Kenya. The study shows that the presence of single and multiple antenatal parasitic infections is associated with impaired infant IgG levels against Haemophilus influenzae (Hib) and diphtheria (DT) antigens post-vaccination from birth to 30 months of age. This study found that the response to DT was reduced in malaria-tolerized infants, and the response to Hib was impaired in filarial-tolerized infants; by contrast, the Schistosoma-tolerized group showed no effect. Deworming campaigns must be directed towards pregnant mothers, infants, and young children to improve response to vaccination.

This study examined the hypothesis that the nature of the host cellular immune response to schistosome ova is a risk factor for urinary tract morbidity in areas in which Schistosoma haematobium is endemic. S. haematobium-infected children and adolescents with bladder pathology assessed by ultrasonography had 54-fold greater tumor necrosis factor (TNF)-alpha production and a 120-fold greater ratio of TNF-alpha to interleukin (IL)-10 release by peripheral blood mononuclear cells in response to egg antigens, in comparison with control children and adolescents matched by age, sex, and infection severity. Mycobacterial antigens also stimulated 7-fold more TNF-alpha among subjects with bladder morbidity than in control subjects, which suggests an innate predisposition to enhanced TNF-alpha production. Levels of egg antigen-induced IL-4 and -5 and interferon-gamma were equivalent in subjects with and without bladder pathology. Thus, children and adolescents predisposed to increased TNF-alpha production to S. haematobium infection are more likely to develop an exaggerated granulomatous response to ova trapped in the bladder wall, with associated urinary tract pathology.

Severe periportal fibrosis is not an inevitable consequence of infection with Schistosoma mansoni. Genetic predisposition may be a deciding factor in the development of disease. To assess the contribution of genetic factors in the severity of hepatic fibrosis, the degree of familial aggregation was determined in a Kenyan population. Schistosomal fibrosis was identified with hepatic ultrasound and newly proposed World Health Organization criteria, which include both qualitative and quantitative observations. These 2 aspects of the criteria correlated well with one another. The peak prevalence of ultrasound proven fibrosis trailed 5-10 years behind peak prevalence of infection and declined sharply after age 50 years. This pattern was consistent with either resolution of severe fibrosis over 10-20 years or early death of those severely affected. Genetic predisposition appears to be a weak factor in the development of severe disease in this population, since no household or familial aggregation could be identified.

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. For schistosomiasis, the bead assay had an estimated sensitivity of 81% and a specificity of 45%, and it was more sensitive than ELISA or urine egg counts for diagnosing infection. For filariasis, it had a sensitivity of 86% and a specificity of 39%, and it was more sensitive than ELISA or RDT. Measuring antibody by MFI is feasible and may provide more accurate epidemiological information than current parasitological tests, especially in the setting of low-intensity infections. Copyright © 2014 by The American Society of Tropical Medicine and Hygiene.

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. Of the five methods, light traps were the most efficient for collecting female Anopheles gambiae s.l. (Giles) (Diptera: Culicidae) and Anopheles funestus (Giles) (Diptera: Culicidae) mosquitoes, whereas the Prokopack aspirator was most efficient in collecting Culex quinquefasciatus (Say) (Diptera: Culicidae) and other culicines. With the low vector densities here, and across much of sub-Saharan Africa, wherever malaria interventions, long-lasting insecticidal nets, and/or indoor residual spraying are in place, the use of a single mosquito collection method will not be sufficient to achieve a representative sample of mosquito population structure. Light traps will remain a relevant tool for host-seeking mosquitoes, especially in the absence of human landing catches. For a fair representation of the indoor mosquito population, light traps will have to be supplemented with aspirator use, which has potential for routine monitoring of indoor resting mosquitoes, and can substitute the more labor-intensive and intrusive pyrethrum spray catches. There are still no sufficiently efficient mosquito collection methods for sampling outdoor mosquitoes, particularly those that are bloodfed.

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. This makes it difficult to estimate the disease burden specific to schistosomiasis using the standard DALY metric. Methodology/Principal Findings In our study, we used Pediatric Quality of Life Inventory (PedsQL), a modular instrument available for ages 2–18 years, to assess health-related quality of life (HrQoL) among children living in a Schistosoma haematobium-endemic area in coastal Kenya. The PedsQL questionnaires were administered by interview to children aged 5–18 years (and their parents) in five villages spread across three districts. HrQoL (total score) was significantly lower in villages with high prevalence of S. haematobium (−4.0%, p, Author Summary Because urogenital schistosomiasis is a multi-decadal chronic disease that begins in early childhood, and because it is a disease that may affect nearly everyone in endemic communities, its impact on personal health-related quality of life (HrQoL) has been difficult to gauge accurately. In order to provide a more precise estimate of schistosomiasis' impact on overall health status, we used a standardized questionnaire, the PedsQL SF15 Inventory, to interview children, aged 5–18 years, and their parents, to quantify their reported physical, social, emotional, and scholastic performance status. Scores were significantly lower in villages having high Schistosoma prevalence, as compared those having moderate prevalence. In adjusting for age, sex, socioeconomic standing, undernutrition, anemia, and hookworm parasites, we found that relative poverty, stunting, wasting, and S. haematobium infection were significant correlates of HrQoL scores, with differential effects in high- and moderate-prevalence communities. The greatest differences were noted in the psychosocial domains of performance. We conclude that exposure to urogenital schistosomiasis has an overall detrimental effect on HrQoL at a level of 2–4% impairment. New implementation of better diagnostics for children is expected to refine our estimates of this association, as will follow-up studies of HrQoL following effective individual and community deworming.

Ecologic modeling of Schistosoma transmission in endemic communities has suggested that antiparasite therapy targeted at the most heavily infected segment of the human population (i.e., school-age children) should have a significant impact on local parasite transmission. Our 1984-1991 experience with age-targeted therapy in the Msambweni area of Kenya has shown an overall decrease in area transmission within 1-2 years following initiation of annual treatment of school-age groups. Snail monitoring confirmed a continuing but variable reduction of vector infection rates. However, subgroup analysis showed significant differences in transmission suppression between more developed coastal villages with piped-water kiosks and villages with only limited access to safe water supplies. Villages without piped water were marked by higher initial prevalences of S. haematobium infection, greater prevalence among adults, longer and more frequent contact with high-risk water sources, and persistently high transmission despite compliance with parasitologic screening or drug therapy. We conclude that targeted therapy had a significant impact on S. haematobium transmission in some areas, but that more extensive or more prolonged coverage is necessary to reduce the rate of new infection in high-risk villages. Defining field-use algorithms, based on decision analysis of economic and ecologic parameters, should provide effective guidelines for selective versus mass treatment in expanded control areas.

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. A proportionate hole index (pHI) was used as a standard measure, and the cut-offs for an ‘effective net’ (offer substantial protection against mosquito bites) and ‘ineffective nets’ (offer little or no protection against mosquito bites) were determined (pHI ≤88 (about ≤500 cm2 of holes surface area) and pHI of >88 (≥500 cm2 of holes surface area), respectively). Results The vast majority (78%) of the surveyed nets had some holes. The median pHI was 92 (range: 1–2,980). Overall, half of the nets were categorized as ‘effective nets’ or ‘serviceable nets’. Physical deterioration of nets was associated with higher use and washing frequency. Young children and older children were found to use ineffective bed nets significantly more often than infants, while the physical integrity of nets owned by pregnant women was similar to those owned by infants. Estuarine environment inhabitants owned nets with the worst physical condition, while nets owned by the coastal slope inhabitants were in fairly good physical condition. The results suggest that bed nets are optimally utilized when they are new and physically intact. Thereafter, bed net utilization decreases gradually with increasing physical deterioration, with most net owners withdrawing physically damaged nets from routine use. This withdrawal commonly happens following 1.5 years of use, making bed net use the most important predictor of physical integrity. On average, the nets were washed twice within six months prior to the survey. Washing frequency was significantly influenced by the bed net colour and bed net age. Lack of knowledge on reasons for net retreatment and the retreatment procedure was evident, while net repair was minimal and did not seem to improve the physical condition of the nets. The “catch-up” bed net distribution strategies are sufficient for ensuring adequate ownership and utilization of ‘effective nets’ in the targeted groups, but bi-annual mass distribution is necessary to provide similar ownership and utilization for the other groups not targeted by “catch-up” strategies. Conclusions Monitoring and maintenance strategies that will deliver locally appropriate education messages on net washing and repair will enhance the effectiveness of malaria control programmes, and further research to assess ineffective nets need is needed.

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. haematobium (25-62%), hookworm (11-28%), and falciparum malaria (8-24%). Over one-half of children were anemic, with high rates of acute and chronic malnutrition. Associations with infection status showed significant age and sex differences. For boys, young age, low socioeconomic standing (SES), S. haematobium, and/or malaria infections were associated with greater odds of anemia, wasting, and/or stunting; for girls, heavy S. haematobium infection and age were the significant cofactors for anemia, whereas low SES and older age were linked to stunting. The broad overlap of infection-related causes for anemia and malnutrition and the high frequency of polyparasitic infections suggest that there will be significant advantages to integrated parasite control in this area. Copyright © 2013 by The American Society of Tropical Medicine and Hygiene.

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. Isolation of DNA was simplified by blotting snail tissue (extracted in NaOH/sodium dodecyl sulfate) onto treated membranes, which enabled preservation at ambient temperatures. A ready-mix of LAMP reagents, suitable for shipment at ambient temperature and storage in minimal refrigeration, was used. Local survey teams without experience in molecular biology acquired operational expertise with this test within a few hours. Fifty-four field-caught snails were tested locally by LAMP and 59 were tested at similar conditions in Jerusalem. The LAMP results were consistent with those of a polymerase chain reaction; only four samples showed false-negative results. Results indicate that LAMP assays are suitable for detection of S. haematobium and S. mansoni in low-technology parasitology laboratories in which schistosomiasis elimination activities are undertaken.

In schistosomiasis elimination programs, successful discrimination of Schistosoma haematobium from the related animal Schistosoma parasites will be essential for accurate detection of human parasite transmission. Polymerase chain reaction assays employing primers from two newly selected repeated sequences, named Sh73 and Sh77, did not discriminate S. haematobium when amplifying Sh73-77 intra- or inter-repeats. However, amplification between Sh73 and the previously described DraI repeat exhibited discriminative banding patterns for S. haematobium and Schistosoma bovis (sensitivity 1 pg and 10 pg, respectively). It also enabled banding pattern discrimination of Schistosoma curassoni and Schistosoma intercalatum, but Schistosoma mattheei and Schistosoma margrebowiei did not yield amplicons. Similar inter-repeat amplification between Sh77 and DraI yielded amplicons with discriminative banding for S. haematobium, and S. bovis; however, S. mattheei was detected only at low sensitivity (1 ng). The Sh73/DraI assay detected snails infected with S. haematobium, S. bovis, or both, and should prove useful for screening snails where discrimination of S. haematobium from related schistosomes is required.

In utero priming to malaria antigens renders cord blood mononuclear cells (CBMC) more susceptible to productive HIV infection in vitro in the absence of exogenous stimulation. This provides a unique model to better understand mechanisms affecting lymphocyte susceptibility to HIV infection in vivo. Effector memory CD3(+)CD4(+) T cells (T(EM)) were the exclusive initial targets of HIV with rapid spread to central memory cells. HIV susceptibility correlated with increased expression of CD25 and HLA-DR on T(EM). Virus entered all samples equally, however gag/pol RNA was only detected in HIV susceptible samples, suggesting regulation of proviral gene transcription. Targeted analysis of human genes in memory T cells showed greater expression of IFNG, NFATc1, IRF1, FOS, and PPIA and decreased expression YY1 and TFCP2 in HIV susceptible samples. Thus fetal priming to exogenous antigens enhances specific proviral gene transcription pathways in effector memory cells that may increase risk of vertical transmission of HIV.

Background To date, there has been no standardized approach to the assessment of aerobic fitness among children who harbor parasites. In quantifying the disability associated with individual or multiple chronic infections, accurate measures of physical fitness are important metrics. This is because exercise intolerance, as seen with anemia and many other chronic disorders, reflects the body's inability to maintain adequate oxygen supply (VO2 max) to the motor tissues, which is frequently linked to reduced quality-of-life in terms of physical and job performance. The objective of our study was to examine the associations between polyparasitism, anemia, and reduced fitness in a high risk Kenyan population using novel implementation of the 20-meter shuttle run test (20mSRT), a well-standardized, low-technology physical fitness test. Methodology/Principal Findings Four villages in coastal Kenya were surveyed during 2009–2010. Children 5–18 years were tested for infection with Schistosoma haematobium (Sh), malaria, filaria, and geohelminth infections by standard methods. After anthropometric and hemoglobin testing, fitness was assessed with the 20 mSRT. The 20 mSRT proved easy to perform, requiring only minimal staff training. Parasitology revealed high prevalence of single and multiple parasitic infections in all villages, with Sh being the most common (25–62%). Anemia prevalence was 45–58%. Using multiply-adjusted linear modeling that accounted for household clustering, decreased aerobic capacity was significantly associated with anemia, stunting, and wasting, with some gender differences. Conclusions/Significance The 20 mSRT, which has excellent correlation with VO2, is a highly feasible fitness test for low-resource settings. Our results indicate impaired fitness is common in areas endemic for parasites, where, at least in part, low fitness scores are likely to result from anemia and stunting associated with chronic infection. The 20 mSRT should be used as a common metric to quantify physical fitness and compare sub-clinical disability across many different disorders and community settings., Author Summary Reduced physical fitness, which is a manifestation of the body's inability to maintain adequate oxygen supply to the tissues, can have many causes. In developing countries, a person's low physical fitness is often the result of anemia and undernutrition, which have multifactorial etiologies including poor diet and chronic infections such as malaria, hookworm and schistosomiasis. In past surveys, exercise tolerance has been measured using non-standardized tests that were poorly-suited to young children. In this study, we implemented a well-validated and reliable 20-meter shuttle run test in a low-resource area of Kenya. Results for 1950 children, aged 5–18 years, showed that impaired fitness was common and associated with anemia and poor growth with boys being more affected than girls. The 20 mSRT is a feasible and low-cost tool that can be easily delivered in low-resource settings to identify children who manifest the disabling but often sub-clinical manifestations of their disease. We propose its implementation as a standard fitness test in less developed areas to allow comparisons across morbidity studies assessing the impact of different interventions.

Background In endemic areas, Rift Valley fever virus (RVFV) is a significant threat to both human and animal health. Goals of this study were to measure human anti-RVFV seroprevalence in a high-risk area following the 2006–2007 Kenyan Rift Valley Fever (RVF) epidemic, to identify risk factors for interval seroconversion, and to monitor individuals previously exposed to RVFV in order to document the persistence of their anti-RVFV antibodies. Methodology/Findings We conducted a village cohort study in Ijara District, Northeastern Province, Kenya. One hundred two individuals tested for RVFV exposure before the 2006–2007 RVF outbreak were restudied to determine interval anti-RVFV seroconversion and persistence of humoral immunity since 2006. Ninety-two additional subjects were enrolled from randomly selected households to help identify risk factors for current seropositivity. Overall, 44/194 or 23% (CI95%:17%–29%) of local residents were RVFV seropositive. 1/85 at-risk individuals restudied in the follow-up cohort had seroconverted since early 2006. 27/92 (29%, CI95%: 20%–39%) of newly tested individuals were seropositive. All 13 individuals with positive titers (by plaque reduction neutralization testing (PRNT80)) in 2006 remained positive in 2009. After adjustment in multivariable logistic models, age, village, and drinking raw milk were significantly associated with RVFV seropositivity. Visual impairment (defined as ≤20/80) was much more likely in the RVFV-seropositive group (P1∶40 for more than 3 years. In concordance with previous studies, residents of the more rural village were more likely to be seropositive and RVFV seropositivity was associated with poor visual acuity. Raw milk consumption was strongly associated with RVFV exposure, which may represent an important new focus for public health education during future RVF outbreaks., Author Summary RVFV infection causes significant disease in both human and animal populations, resulting in significant agricultural, economic and public health consequences. We conducted a cohort study on residents of a high-risk area to measure human anti-RVFV seroprevalence, to identify risk factors, and to estimate the durability of prior RVFV immunity. One hundred two individuals tested for RVFV exposure before the 2006–2007 RVF outbreak were restudied to determine interval anti-RVFV seroconversion and persistence of humoral immunity since 2006. Ninety-two additional subjects were enrolled from randomly selected households to help identify risk factors for current seropositivity. Seroprevalence in the region was high (23%). 1/85 at-risk individuals restudied in the follow-up cohort had seroconverted since early 2006. 29% of newly tested individuals were seropositive. After adjustment in multivariable logistic models, age, village, and drinking raw milk were significantly associated with RVFV seropositivity. Visual impairment (defined as ≤20/80) was much more likely in the RVFV-seropositive group. Among those with previous exposure, RVFV titers remained at protective levels (>1∶40) for more than 3 years. This study highlights the high seroprevalence among Northeastern Kenyans and the ongoing surge in seroprevalence with each RVF outbreak.

Monitoring post-control transmission of schistosomes by examining humans becomes less effective as infection rates among humans decrease. Molecular monitoring of prepatent schistosome infection in snails by the polymerase chain reaction (PCR) has been used for studying human-to-snail transmission, and snail prepatent infection rates were found to correspond to infection prevalence and average intensity in human populations contacting the sites studied. We have now developed loop-mediated isothermal amplification (LAMP) assays for identifying Schistosoma mansoni and S. haematobium to facilitate large-scale evaluation of post-intervention transmission potential. LAMP primers were designed based on the Sm1-7 and DraI repeated sequences of the corresponding schistosomes, and amplification by LAMP of these 121-basepair highly abundant sequences provided a detection sensitivity of 0.1 fg of genomic DNA. When these LAMP assays were applied for examining infected laboratory snails, it was possible to identify infection from the first day after exposure to miracidia. The potential advantages of these assays are discussed.