Spatial and network mapping of comorbidity with trachoma and visual-impairing NCDs in a pastoralist community in Kenya: implications for SDGs and UHC.

BACKGROUND: We explore the spatial distribution of comorbidity with trachoma and potentially visual-impairing non-communicable diseases (NCDs) and their risk factors among Kenyan pastoralists. METHODS: Using a cross-sectional study design, we recruited and clinically examined 262 study participants for NCDs (hypertension or diabetes) and trachoma using the World Health Organization grading system. Network models estimated interactions and risks linked with trachoma and NCDs while the Poisson point process determined their spatial distribution. RESULTS: Of the 262 participants, 140 (53%) had trachoma, with >71% of these cases identified among females and those >60 y of age. A total of 36 trachoma cases co-occurred with hypertension (26%) and diabetes (0.01%). NCDs were frequent among those with recurring trachoma (21%) and trachomatous trichiasis (14.3%). Trachoma and NCDs clustered together in <1 km distances (R=0.18, p=0.02). In network analysis, age was strongly associated with trachoma and NCDs. Trachoma was linked with geographic location while diabetes was linked with water source distances. Education level became the central risk factor. CONCLUSIONS: We demonstrate a twin trachoma-NCD burden that is higher among elderly pastoralists in southern Kenya. Attenuating adverse population-level visual impairment, including integrating the trachoma SAFE strategy with NCD comprehensive care, amplifies the benefits from economies of scale, accelerating realization of Sustainable Development Goal 3 and universal health coverage in hard-to-reach areas.

Longitudinal analyses suggest a higher burden of self-reported influenza-like illness among women and girls in a rural community in western Kenya.

Longitudinal studies that quantify influenza-like illness (ILI) burden while determining associated risk factors and intra-cluster correlation coefficients (ICCs) are scarce in Africa. This study aimed to identify longitudinal patterns of ILI and the associated independent variables while quantifying the burden by age and sex. We enrolled and followed 390 subjects nested within 92 households for 12 weeks, collecting weekly data on prespecified self-reported symptoms in a rural community in western Kenya. Using a standard case definition, reporting at least any four prespecified symptoms attained an ILI syndrome. Analyses related relationship between attaining ILI syndrome and independent variables using multilevel logistic regression models adjusting for age and sex. ICCs quantified clustering of ILI syndrome computed at different levels of data aggregation. Of the 4261 reports received, 592 (14%) registered an illness, with 278 (48%) of these attaining ILI syndrome. The 278 reports belonged to 176 (41%) subjects dwelling in 76 (83%) households. On average, each study subject and household experienced 1.6 and 3.7 episodes of ILI syndrome, respectively. Making a visit outside the local area of residence (Odds ratio (OR) =2.7, 95% CI 1.8, 4.1) and living in a cement-floored house (OR = 1.9, 95% CI 1.1, 3.3) independently predicted attaining ILI syndrome. Correcting for the population structure revealed an excess risk of 16% in attaining the syndrome among the study women and girls. Clustering of ILI syndrome was lowest at the individual level (ICC = 0.04) and slightly higher within households (ICC = 0.14), suggesting moderate household contextual influences. Regardless of the cause, we provide evidence of a potentially higher ILI syndrome burden among women and girls in our study area. Studies are needed to establish granular exposures defining the increasing risk of ILI syndrome associated with gender, making a visit outside the local sub-county of residence and living in a cement-floored house.

High MERS-CoV seropositivity associated with camel herd profile, husbandry practices and household socio-demographic characteristics in Northern Kenya.

Despite high exposure to Middle East respiratory syndrome coronavirus (MERS-CoV), the predictors for seropositivity in the context of husbandry practices for camels in Eastern Africa are not well understood. We conducted a cross-sectional survey to describe the camel herd profile and determine the factors associated with MERS-CoV seropositivity in Northern Kenya. We enrolled 29 camel-owning households and administered questionnaires to collect herd and household data. Serum samples collected from 493 randomly selected camels were tested for anti-MERS-CoV antibodies using a microneutralisation assay, and regression analysis used to correlate herd and household characteristics with camel seropositivity. Households reared camels (median = 23 camels and IQR 16-56), and at least one other livestock species in two distinct herds; a home herd kept near homesteads, and a range/fora herd that resided far from the homestead. The overall MERS-CoV IgG seropositivity was 76.3%, with no statistically significant difference between home and fora herds. Significant predictors for seropositivity (P ⩽ 0.05) included camels 6-10 years old (aOR 2.3, 95% CI 1.0-5.2), herds with ⩾25 camels (aOR 2.0, 95% CI 1.2-3.4) and camels from Gabra community (aOR 2.3, 95% CI 1.2-4.2). These results suggest high levels of virus transmission among camels, with potential for human infection.

Peste Des Petits Ruminants (PPR) in Dromedary Camels and Small Ruminants in Mandera and Wajir Counties of Kenya.

A study was conducted to determine the presence of Peste des petits ruminants (PPR) in camel population kept together with small ruminants in Isiolo, Mandera, Marsabit, and Wajir counties of Kenya. This was done in the wake of a disease with unknown etiology "Camel Sudden Death Syndrome" camels in the horn of Africa. Thirty-eight (38) samples, 12, 8, 15, and 3 samples, were collected from Mandera, Wajir, Isiolo, and Marsabit, respectively, from 25 camels, 7 goats, and 4 sheep. One camel in Mandera and one goat in Wajir were confirmed positive for PPR virus (PPRV) through reverse Polymerase Chain Reaction. The analysis of sequences revealed closest nucleotide identities of obtained sequences from both goat and camel to the lineage III of PPRV albeit with 60.29% of nucleotide identity. This study establishes that camels in the study area suffer with PPR manifest clinical signs that are mainly characterized by inappetence, loss of body condition, and general weakness terminally leading to diarrhea, conjunctivitis, and ocular nasal discharges preceding death. These clinical signs are similar to those observed in small ruminants with slight variations of manifestations such as keratoconjunctivitis as well as edema of the ventral surface of the abdomen. This shows that camels could be involved in the epidemiology of PPR in the region and that PPRV could be involved in the epidemics of Camel Sudden Death syndrome. There is therefore a need for resources to be dedicated in understanding the role camels play in the epidemiology of PPR and the role of the disease in Camels Sudden death syndrome.

Effects of climate change on the occurrence and distribution of livestock diseases.

The planet's mean air and ocean temperatures have been rising over the last century because of increasing greenhouse gas (GHG) emissions. These changes have substantial effects on the epidemiology of infectious diseases. We describe direct and indirect processes linking climate change and infectious diseases in livestock with reference to specific case studies. Some of the studies are used to show a positive association between temperature and expansion of the geographical ranges of arthropod vectors (e.g. Culicoides imicola, which transmits bluetongue virus) while others are used to illustrate an opposite trend (e.g. tsetse flies that transmit a range of trypanosome parasites in sub-Saharan Africa). We further describe a positive association between extreme events: droughts and El Niño/southern oscillation (ENSO) weather patterns and Rift Valley fever outbreaks in East Africa and some adaptation practices used to mitigate the impacts of climate change that may increase risk of exposure to infectious pathogens. We conclude by outlining mitigation and adaptation measures that can be used specifically in the livestock sector to minimize the impacts of climate change-associated livestock diseases.

Seroprevalence of Anaplasma marginale and Babesia bigemina infections and associated risk factors in Machakos County, Kenya.

Anaplasma marginale and Babesia bigemina are important tick-borne pathogens of cattle. A cross-sectional survey was undertaken to determine the seroprevalence of A. marginale and B. bigemina infections and identify associated risk factors on traditional smallholder farms in Machakos County, Kenya. A total of 421 cattle from 127 farms from four divisions in the county were sampled and visited between September and November 2007. The farms were selected by a proportional allocation approach based on the number of farms in the four divisions previously selected by stratified random sampling method. Information on animal and individual farm management variables was obtained using standardized questionnaires. Prevalence of serum antibodies due to A. marginale and B. bigemina pathogens was determined using the enzyme-linked immunosorbent assay (ELISA) technique. The relationship between the seropositivity and associated risk factors was assessed by multivariable analyses using standard logistic regression models. The overall estimation (and their 95% confidence intervals) of A. marginale and B. bigemina seropositivity at the animal level was 53.4% (48.5%, 58.2%) and 40.6% (35.8%, 45.4%), respectively. Two variables, "animal age" and "administrative division," were significantly associated with the A. marginale seroresponse. Three variables, "animal age" "grazing system" and "administrative division" were significantly associated with the B. bigemina seroresponse. These findings suggest possible indicators of existence of endemic instability for the two infections. The study identifies characterization of environmental suitability for the vectors and how they interact with grazing systems to cause the infections as an area for further studies, for improved understanding of the infections and in designing disease control programs.

Population attributable fractions of farm vector tick (Rhipicephalus appendiculatus) presence on Theileria parva infection seroprevalence under endemic instability.

The primary objective of this study was to assess the impact of Rhipicephalus appendiculatus tick presence (exposure variable) on Theileria parva infection seroprevalence (outcome variable) in a group of cattle belonging to a farm using population attributable fractions (PAF). The analyses were based on a representative sample of 80 traditional smallholder mixed farms. The farms were selected by first stratifying the population administratively and implementing a multistage random sampling in Mbeere district in Kenya. The PAFs were estimated using the stratified, Bruzzi, and sequential partitioned PAF approaches. A secondary objective was, thus, to evaluate the impact of the approaches on the PAF estimates. The stratified and Bruzzi approaches estimated proportion of T. parva infection cases directly attributable to the exposure after controlling for confounding by agro-ecological zone (AEZ). The sequential partitioned PAF approach estimated a PAF associated with exposure after adjusting for any effect that the AEZ may have had by influencing the prevalence of the exposure. All analyses were carried out at the farm level where a farm was classified as infested if the tick was found on cattle on a farm, and infected if at least one animal on a farm was positive for T. parva antibodies. Variance estimation for PAFs was implemented using 'delete-a-group' jackknife re-sampling method. The stratified PAF (26.7% [95% CI: 9.0%, 44.4%]) and Bruzzi PAF (26.4% [95% CI: 9.6%, 43.2%]) were consistent in estimating a relatively low impact of farm vector tick presence with a relatively high level of uncertainty. The partitioned PAF (15.5% [95% CI: 1.5%, 29.6%]) suggested that part of the impacts estimated using the stratified PAF and Bruzzi approaches was driven by AEZ effects. Overall, the results suggested that under endemic instability in Mbeere district, (1) presence of R. appendiculatus was not a good indicator of T. parva infection occurrence on a farm; (2) ecological variation could play a role in determining infection impacts. This study provides a preliminary basis for evaluating the potential value and utility of estimating PAFs for variables amenable to control in tick-borne diseases (TBDs) epidemiological studies.

The 2006-2007 Rift Valley fever outbreak in Kenya: sources of early warning messages and response measures implemented by the Department of Veterinary Services.

The authors characterised sources of early warning messages about occurrences of Rift Valley fever (RVF) and examined the response measures that were used by the Department of Veterinary Services (DVS) to manage the 2006-2007 RVF outbreaks in Kenya. The study was conducted between November 2009 and March 2010 and it included national, provincial and district veterinary officers who were involved in the management of the outbreak. Structured questionnaires were used to collect the data. Although the majority of the respondents reported having limited capacity to implement response measures, they perceived that the measures implemented were effective. Vaccination, movement control and market closures were the main response measures implemented, particularly in districts that had cases in both livestock and humans. Vaccination, however, was implemented too late and the coverage achieved was too low to be effective. The authors suggest ways to improve the capacity of the DVS to respond to similar outbreaks in the future.

Estimating seroprevalence and variation to four tick-borne infections and determination of associated risk factors in cattle under traditional mixed farming system in Mbeere District, Kenya.

A cross-sectional study of serum antibody responses of cattle to tick-borne disease (TBD) parasites (Theileria parva, Theileria mutans, Anaplasma marginale and Babesia bigemina) was conducted on traditional smallholder mixed farms in Mbeere District in Kenya. The objective was to estimate the infections' seroprevalence and variation and identify associated risk factors. A total of 440 cattle in 80 farms, selected by stratified random sampling from the four divisions in the district, were surveyed. Information on animal and on each farm's management practices, particularly on tick control practices, was obtained by personal interview using a standardized questionnaire. Prevalences of serum antibodies were determined using the enzyme-linked immunosorbent assay (ELISA) technique. The relationship between TBDs seroprevalence and the risk factors was assessed by multivariable analysis using standard logistic regression models and mixed models using the farm as a random effect. Overall estimation of seroprevalences and their 95% confidence limits were: T. parva (19% [14%, 25%]), T. mutans (25% [20%, 29%]), A. marginale (58% [52%, 64%]) and B. bigemina (19% [15%, 23%]). Analysis in presence of extra-binomial variation under Analysis Of Variance (ANOVA) yielded relatively larger intra-farm correlation coefficient (ICC) (0.3) and variance-inflation factor (VIF) (2.35) values for T. parva than for the other parasites [range, 0.05-0.07 (for ICC) and 1.02-1.32 (for VIF)]. Both farm- and area-level variables had variably significant and large effects on all infections, but these were more pronounced on T. parva seroprevalence. Inclusion of farm random effect resulted in substantially higher estimate of farm variance component for T. parva infection (1.73) compared to other infections [range, 0.29-0.56], comparable ICC values with those under ANOVA analysis [range, 0.08-0.35] and a substantially better fit than the standard multivariable logistic regressions. The above results serve as possible indicators of existence of endemic instability for the studied TBD infections in the district. A probable differential ecological and climatic variability in vector suitability habitats, particularly for T. parva vector, was likely in Mbeere District and this was suggested to influence farm tick control management across the area. Implications of the design-based sampling and analyses on the above results are also discussed.

Seroprevalence of Cysticercus cellulosae and associated risk factors in free-range pigs in Kenya.

Porcine cysticercosis is an emerging zoonosis with public health and economic importance. A cross-sectional study was undertaken to investigate the disease in free-range pigs on 182 smallholder farms in Busia District, Kenya. The survey households were selected using a snowballing technique. Serum samples were obtained from 284 pigs of all ages at farm level and 37 pigs from slaughter slabs in the study area. The samples were analysed for the presence of cysticercus antigen using an antigen enzyme-linked immunosorbent assay (ELISA). A structured questionnaire was administered to determine the risk factors for porcine cysticercosis on the study farms. At pig level, the total number of pigs testing positive were 11, resulting in a seroprevalence of 4% (95% confidence interval (CI): 1.9-6.2%), while the farms with a positive pig were 9% (95% CI: 3.9-14.1%). All pigs examined in the slaughter slab survey were seronegative. The distribution of possible risk factors for porcine cysticercosis that were observed at farm level was as follows: free-range pig keeping (100%), history of human taeniosis infection in a family (51%), slaughtering of pigs at home (20%), lack of meat inspection (15%) and absence of latrines (15%). The only significant (χ2 = 4.4, P = 0.034, odds ratio (OR) = 3.8) risk factor associated with the occurrence of cysticercosis was lack of latrines at household level. The study shows that porcine cysticercosis is prevalent in free-range pigs in Busia District, Kenya and thus control measures need to be instituted.