Kairu-Wanyoike, S. W. | bioRxiv Science

bioRxiv2020

Leptospira spp. seroprevalence in humans involved in a cross-sectional study in Garissa and Tana River Counties, Kenya

IntroductionLeptospirosis is a neglected bacterial zoonotic infection caused by spirochetes of Leptospira genus. Humans get infected through direct or indirect contact with urine of infected animals or environment. It accounts for more than 300,000 severe cases annually worldwide with case fatality rates of over 30%. Costs of diagnosis and treatment for human and animals, disruption of international trade of animals and products, reduced productivity and reproductivity in animals constitute economic importance. In Kenya, leptospirosis burden is significant but under-diagnosis and under-reporting affects the awareness of the disease. This study aimed to determine and compare the sero-prevalence and factors associated with Leptospira spp. in the two counties. MethodsWe conducted a cross-sectional study that involved apparently healthy people of at least 5 years of age in randomly selected households in Garissa and Tana River Counties. Blood samples were collected and tested for Leptospira spp antibodies using IgM ELISA. Standardized structured questionnaires were administered to collect socio-demographic and exposure information. We calculated frequencies and proportions for categorical variables and odds ratios (OR) and 95% confidence interval (CI) to evaluate association between sero-positivity and exposure factors. We used Wilcoxon test to evaluate statistical difference in sero-positivity for continuous variables and calculated test statistic (H) and p-value. ResultsA total of 952 subjects were recruited into the study - these included 482 persons from Garissa and 470 from Tana River. The overall sero-prevalence was 26% [(244/952); (CI: 23% to 29%)]. Garissa County had significantly higher Leptospira spp. seroprevalence (31%, n = 147; CI: 27% to 35%) compared to Tana River County (21 %, n = 97; CI: 17% to 25%). Being a female (OR=1.6, CI: 1.2-2.2) and engaging in pastoralism (OR=2.7, CI: 1.8-3.9) were significantly associated with higher odds of Leptospira spp. seropositivity compared to being a male or working in irrigated areas. The mean altitude of residence of sero-positive patients was 73m {+/-} 21 SD (standard deviation) above sea level and that for sero-negative was 80m {+/-} 22 SD (H=35, p-value = 0.00). ConclusionThis study determined the seroprevalence and risk factors for Leptospira spp. exposure in Garissa and Tana River Counties, Kenya. Females in pastoral communities experience high burden of the disease. Enhanced surveillance in humans and animals and further research is required to understand the complex and multifactorial drivers of leptospirosis transmission in the two Counties.

microbiology↗

bioRxiv2020

Epidemiological study on foot-and-mouth disease in small ruminants: sero-prevalence and risk factor assessment in Kenya

Foot-and-mouth disease (FMD) is endemic in Kenya affecting cloven-hoofed ruminants. The epidemiology of the disease in small ruminants (SR) is not documented. We carried out a cross-sectional study, the first in Kenya, to estimate the sero-prevalence of FMD in SR and the associated risk factors nationally. Selection of animals to be sampled used a multistage cluster sampling approach. Serum samples totaling 7564 were screened for FMD antibodies of Non-Structural-Proteins using ID Screen(R) NSP Competition ELISA kit. Data were analysed using Statistical Package for Social Studies Version 20. To identify the risk factors, chi-square and logistic regression analyses were used. The country animal level sero-prevalence was 23.3% (95% CI: 22.3-24.3%) while herd level sero-prevalence was 77.6% (95% CI: 73.9-80.9%). Sero-positivity was significantly higher in the pastoral zone (31.5%) than in the sedentary zone at 14.5% ({chi}2 =303.2, p<0.05). In the most parsimonious backward fitting logistic multivariable regression, the only risk factors that were significantly positively associated with FMD sero-positivity in SR were multipurpose (OR=1.150; p=0.034) and dairy production types (OR=2.029; p=0.003). Those that were significantly negatively associated with FMD sero-positivity were male sex (OR=0.856; p=0.026), young age (OR=0.601; p=0.037), sedentary production zone (OR=0.471; p<0.001), bringing in of SR (OR=0.838; p=0.004), purchase of SR from market/middlemen (OR=0.877; p=0.049), no interaction with wildlife (OR=0.657; p<0.001), mixed production type (OR=0.701; p=0.016), enclosure of SR day and night (OR=0.515; p=0.001), migratory grazing system (OR=0.807; p=0.047), on-farm watering system (OR=0.724; p=0.002), male-from-another-farm (OR=0.723; p=0.030) and artificial insemination (OR=0.357; p=0.008) breeding methods. This study showed that there is widespread undetected virus circulation in SR indicated by ubiquitous spatial distribution of significant FMD sero-positivity in the country. The risk factors were mainly husbandry related. Strengthening of risk-based FMD surveillance in carrier SR which pose potential risk of virus transmission to other susceptible species is recommended. Adjustment of husbandry practices to control FMD in SR and in-contact species is suggested. Cross-transmission and more risk factors need to be researched.

microbiology↗