Sympatric occurrence of Taenia saginata and Sarcocystis spp. in cattle from Narok County, Kenya: meat inspection findings with molecular validation.

The epidemiological picture of Taenia saginata infections in Kenya is fragmented with limited available data. Although Sarcocystis species are significant meat-borne parasites, few studies have explored their occurrence in Kenya. This study aimed to estimate the occurrence of bovine cysticercosis and screen for the presence of Sarcocystis spp. A meat inspection-based survey was conducted in ten abattoirs in Narok County, Kenya, and inspection for T. saginata cysticerci was limited to the Triceps brachii muscle. The apparent occurrence of the parasite was 5.4% (95% CI, 3.8, 7.6, n=573). Molecular confirmation of T. saginata was done via nested polymerase chain reaction targeting the mitochondrial 12S ribosomal RNA gene and restricted fragment length polymorphism. Sarcocystis species were identified using a multiplex polymerase chain reaction method targeting the 18S ribosomal RNA gene sequences and the mitochondrial cytochrome c oxidase subunit I gene. Of the 31 cystic lesions tested, 26/31 (83.9%) were confirmed to be T. saginata.Sarcocystis cruzi and S. hominis were detected in 8/31 (25.8%) and 1/31 (3.2%) of the cystic lesions, respectively. Co-infections of S. cruzi and T. saginata were found in 6/31 lesions (19.4%). The confirmation of bovine cysticercosis and S. hominis is suggestive of the presence of risky culinary and sanitation practices that facilitate transmission. This is the first report and molecular confirmation of Sarcocystis spp. in cattle in the country. The presence of both zoonotic S. hominis and pathogenic S. cruzi highlights an underexplored concern of veterinary and human health significance, warranting further epidemiological investigation.

Seroprevalence Estimates of Q Fever and the Predictors for the Infection in Cattle, Sheep, and Goats in Nandi County, Kenya.

Q fever is an important worldwide zoonotic disease that affects almost all domestic animals, wildlife, and humans. The infection has both socio-economic and public health significance. A cross-sectional study was carried out to investigate the estimates of seroprevalence of Q fever and to determine the predictors of the infection in cattle, sheep, and goats in six wards of Nandi County. A total of 1,140 blood samples were collected from 366 households. Samples were drawn from 725 cattle (64%), 283 sheep (25%), and 132 goats (11%). Multistage sampling method was adopted. Serum samples were analyzed for antibodies to Coxiella burnetii using the indirect ELISA test. Results showed an overall animal seroprevalence of 5.614% (64/1140) for Q fever. In cattle, the seroprevalence was 8.138% (59/725) with CI 95% (2.8-18.23), 1.413% (4/283) for sheep CI 95% (1.0-7.78), and 0.758% (1/132) goats CI 95% (0.14-7.27). From the findings, Q fever was more prevalent in cattle (OR 7.26) than in sheep and goats. Animal species (p value 0.015, CI 95% OR 7.26) was the only potential predictors in the three considered species for the presence of Coxiella burnetii antibodies. Sex, age, breed, and production system had no statistical significant association for Q fever infection since p value was >0.005. In conclusion, the results demonstrated that cattle, sheep, and goats are widely exposed to Q fever organisms, and hence, it is an important zoonosis in Nandi County. Therefore, to address this "silent" disease, there is an urgent call for both veterinarians and medical personnel to jointly address prevention and control strategy through enhanced surveillance, public sensitization, and awareness creation under the one health concept. There is also a need for enhanced capacity for the diagnosis of Q fever in both animals and humans in Nandi County.

A hundred years of rabies in Kenya and the strategy for eliminating dog-mediated rabies by 2030 [version 2; peer review: 4 approved].

BACKGROUND: Rabies causes an estimated 59,000 human deaths annually. In Kenya, rabies was first reported in a dog in 1912, with the first human case reported in 1928. Here we examine retrospective rabies data in Kenya for the period 1912 - 2017 and describe the spatial and temporal patterns of rabies occurrence in the country. Additionally, we detail Kenya's strategy for the elimination of dog-mediated human rabies by 2030. METHODS: Data on submitted samples and confirmed cases in humans, domestic animals and wildlife were obtained from Kenya's Directorate of Veterinary Services. These data were associated with the geographical regions where the samples originated, and temporal and spatial trends examined. RESULTS: Between 1912 and the mid 1970's, rabies spread across Kenya gradually, with fewer than 50 cases reported per year and less than half of the 47 counties affected. Following an outbreak in the mid 1970's, rabies spread rapidly to more than 85% of counties, with a 4 fold increase in the percent positivity of samples submitted and number of confirmed rabies cases. Since 1958, 7,584 samples from domestic animals (93%), wildlife (5%), and humans (2%) were tested. Over two-thirds of all rabies cases came from six counties, all in close proximity to veterinary diagnostic laboratories, highlighting a limitation of passive surveillance. CONCLUSIONS: Compulsory annual dog vaccinations between 1950's and the early 1970's slowed rabies spread. The rapid spread with peak rabies cases in the 1980's coincided with implementation of structural adjustment programs privatizing the veterinary sector leading to breakdown of rabies control programs. To eliminate human deaths from rabies by 2030, Kenya is implementing a 15-year step-wise strategy based on three pillars: a) mass dog vaccination, b) provision of post-exposure prophylaxis and public awareness and c) improved surveillance for rabies in dogs and humans with prompt responses to rabies outbreaks.

Stinging nettle and neem enhance antibody response to local killed and imported live infectious bursal disease vaccines in indigenous chicken in Kenya.

Immune responses are critical for protection of chickens from infectious bursal disease (IBD). In this study, the antibody response-enhancing effect of drinking water supplementation of 1% stinging nettle and neem on different IBD vaccines and vaccination regimes was evaluated, using 36 (n = 36) specific antibody negative indigenous chicks. The birds were allocated into 3 groups as follows: 1A-C, 2A-C, and 3A-B, while group 3C acted as the unvaccinated non-supplemented control. A local inactivated K1 and imported live attenuated D78 IBD vaccines were given to groups 1A-C and 3A-B at 14 and 28 d of age, respectively. A combination of K1 and D78 vaccines was given 30 d apart to groups 2A and 2B (D78 at 14 and 21 d and K1 at 44 d of age) and on the same d to group 2C at 14 and 28 d of age. Stinging nettle was given in water to groups 1B, 2B, and 2C, and neem to groups 1C, 2A, and 3B. Birds were bled weekly and immune responses monitored using indirect ELISA. Both neem and stinging nettle had antibody response-enhancing effects in groups 1B and 1C, receiving the local inactivated K1 vaccine. There were significant differences (P < 0.05) in antibody titers between groups 1A and 2C. Stinging nettle induced earlier onset of high antibody responses in group 2C and persistent titers (>3.8 log10) from the third week in group 2B. Imported live D78 vaccine induced higher antibody titers compared to the local inactivated K1 vaccine. Groups 2B and 2C receiving a combination of the local K1 and imported live attenuated D78 vaccines had the highest antibody titers. Adoption of stinging nettle supplementation and a prime-boost program involving use of a local virus isolates-derived vaccine is recommended.

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.

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.

The socio-economic impact of important camel diseases as perceived by a pastoralist community in Kenya.

This paper presents the results of a study conducted in a pastoral community in Kenya using participatory appraisal approaches. The objective of the study was to assess the socio-economic impact of camel trypanosomosis (surra) according to the perceptions of the pastoralists. Four livestock grazing units were conveniently selected and in each of them, three groups of key informants comprising five to eight persons were selected for the participatory exercises. Five camel diseases were listed in order of importance according to their severity and frequency of occurrence including trypanosomosis, mange, non-specific diarrhoea, tick infestations and haemorrhagic septicaemia. The losses listed as incurred due to the five diseases were: losses in milk, meat, blood, fats and hides, dowry payments, and depreciation in sale of animals, losses due to infertility and abortions, and losses due to the cost of treatment. There was good agreement (P < 0.05) between the informant groups on the losses incurred as a result of the diseases for all the selected loss indicators. Surra and mange were given high median scores on all the indicators while non-specific diarrhoea, tick infestations, and haemorrhagic septicaemia received moderate median scores. Based on the study findings it is concluded that the camel plays a central role in the lives of Turkana pastoralists and that surra has a devastating social and economic impact. There is a need for veterinary and policy decision-makers to focus more attention on the control of surra in this arid and semi-arid area of Kenya.

Community perceptions of important camel diseases in Lapur Division of Turkana District, Kenya.

This paper presents the results of a study conducted in Lapur Division of Turkana District, Kenya, to estimate the incidence and mortality of camel trypanosomosis using participatory methods. Four livestock camps ('adakars') were conveniently selected for the study. Four informant groups comprising 6 8 key persons were used for the participatory exercises. The camel diseases identified by the pastoralists in their order of importance according to annual incidence were: trypanosomosis (11.4%); mange (10.8%); tick infestation (7.9%); haemorrhagic septicaemia (7.7%); and non-specific diarrhoea (7.6%). Almost half (49.3%) of the camel population suffered from at least one disease over the previous year. The annual incidence and mortality rates of trypanosomosis were estimated at 15%, and 9.9%, in adult camels and 6.9% and 5.2%, in young camels, respectively. There was a seasonal occurrence of trypanosomosis, with most cases reported in the dry season. The prevalence levels of the disease reportedly declined from about 100%, in 1978 to an almost stable state of about 15% in 2002. This study revealed that camel trypanosomosis is still an important disease in Turkana District, exacting a heavy toll in terms of morbidity and mortality. The economic losses due to the disease were likely to have been great owing to the central role the camel plays in this arid district of Kenya.

Comparison of vaccination strategies for the control of dog rabies in Machakos District, Kenya.

Demographic and epidemiological field data were used in a deterministic model to describe dog rabies transmission in Machakos District, Kenya and to predict the impact of potential vaccination strategies for its control. The basic reproduction number (R0) was estimated to be 2.44 (1.52-3.36, 95% confidence limits). There were three key model predictions. The first was that a threshold dog density (K(T)) of 4.5 dogs km(-2) (3.8-5.2 dogs km(-2), 95% confidence limits) was required to maintain transmission. The second was that the estimated annual vaccination rate of 24% failed to decrease incidence and actually increased the stability of transmission and may be counter-productive. Thirdly, to control rabies, it was predicted that 59% (34%-70%, 95% confidence limits) of dogs should be vaccinated at any one time. This requires approximately 70% coverage for annual but only 60% coverage for semi-annual vaccination campaigns. Community-level vaccination trials are needed to test these predictions.

Community-based active surveillance for rabies in Machakos District, Kenya.

The rabies problem in Kenya has been greatest in Machakos District where the disease has persisted endemically for over 40 years. This paper presents the results of a one-year community-based active surveillance for rabies in six randomly selected sublocations in the district for the period 1992-1993. Approximately 860 rabid dogs per 100000 dogs were confirmed in this study, compared to approximately 12 per 100000 confirmed rabid dogs reported by the existing passive-surveillance system. This active surveillance underestimated the true rabies incidence, because only 41% (130/317) of the potential specimens could be diagnosed. Dogs accounted for 92% (179/194) of primary animal-rabies suspects, 80% (66/83) of secondary suspects, and 81% of the confirmed animal-rabies cases. The annual incidence of animal-bites of humans was 234 per 100000 people and the point estimate of human-rabies incidence per year was 25 per million people. Almost all (97%) animal-bites of humans were due to dogs.The traditional passive-surveillance system grossly underestimated the importance of rabies as a public-health problem in Machakos District. Community-based active surveillance provides a potential cost-effective strategy for greatly improving estimates of rabies incidence and epidemiology to inform veterinary and policy decision-making.

Features of dog ecology relevant to rabies spread in Machakos District, Kenya.

A random sample of households in Machakos District of Kenya was surveyed using personal interviews to determine features of dog ecology relevant to the spread of rabies. A mean of 1.35 dogs/household, a dog to person ratio of 1:9.6 and a mean of 10.4 dogs/km2 were estimated. The male to female ratio was 1:0.67 with 26% of the dog population being less than three months old. The dogs had a mean age of 1.8 years. The proportion of the dogs which fed on household leftovers and waste was 94.7%. Dogs were restricted in 19.4% of the households, while 69% of the dogs spent all of their time free outdoors. One-third of the dog population over three months old had been vaccinated against rabies. Considering the endemic status of rabies in Machakos District, methods which could be devised to control the disease are discussed.

Comparison of human immune responses to purified Vero cell and human diploid cell rabies vaccines by using two different antibody titration methods.

Antibody responses to a conventional rabies preexposure regimen of a new purified Vero cell rabies vaccine (PVRV) and a human diploid cell vaccine (HDCV) were compared in 80 healthy Kenyan veterinary students. Forty-three of the students received the PVRV and 37 received the HDCV on days 0, 7, and 28. Antibody responses were monitored by using the rapid fluorescent-focus inhibition test (RFFIT) and an inhibition enzyme immunoassay (INH EIA) on days 0, 7, 28, and 49. Both vaccines elicited a rapid antibody response. A good correlation between the RFFIT titers and the INH EIA titers was obtained (r = 0.90). Our results also showed that the INH EIA was more reproducible and might therefore be a suitable substitute for the more expensive and less reproducible RFFIT. The geometric mean titers determined by both tests in the two groups of students were statistically similar during the test period. The RFFIT and the INH EIA gave comparable geometric mean titers, which differed significantly only on day 28 in the PVRV group. The effect of the new PVRV is comparable to that of the more expensive HDCV, as determined by the present test systems. The PVRV could therefore be the vaccine of choice, especially in tropical rabies-endemic areas, where the high cost of the HDCV has confined its use to a privileged few.