Molecular detection of Anaplasma platys infection in free-roaming dogs and ticks from Kenya and Ivory Coast.

BACKGROUND: Anaplasma platys is a bacterium parasitic in the canine platelets, representing the causative agent of canine cyclic thrombocytopenia, with a worldwide distribution, mainly in tropical countries. The agent has zoonotic potential, being reported in several human clinical cases. The suspected vector is the tick Rhipicephalus sanguineus (sensu lato), widely distributed in animals and humans in the tropical regions of South America, Africa, Asia and Australia, but also in southern Europe. Only few scattered data concerning the epidemiology of A. platys in sub-Saharan Africa are available. The aim of our study was to evaluate the epidemiological status of A. platys in dogs and cats from rural communities in eastern and western Africa, where dogs and their ticks live in close contact with humans. METHODS: A total of 216 canine and 22 feline blood samples and ticks feeding on them were collected in 2013 and 2014 from eight localities in Ivory Coast and four localities in Kenya. PCR was performed using specific primers targeting a portion of the 16S rRNA gene, followed by sequencing. RESULTS: The main results highlight the high prevalence of A. platys infection in dogs in both Eastern and Western Africa and report it for the first time in Eastern Africa and in Rhipicephalus camicasi. CONCLUSIONS: The presence of A. platys DNA in R. camicasi feeding on negative hosts together with the relatively high prevalence of A. platys, correlated with the absence of the probable vector Rhipicephalus sanguineus (s.l.) in Kenyan Island suggest the involvement of other tick species in the transmission of A. platys.

Altitudinal and seasonal differences of tick communities in dogs from pastoralist tribes of Northern Kenya.

Studies regarding the distribution and ecology of ticks in dogs from Eastern Africa are scarce. Our research was based on a long-term screening of ticks parasitising the domestic dogs living with indigenous people around Lake Turkana, Mt. Kulal and Mt. Nyiru areas, Northern Kenya. A total of 9977 ticks were collected from 1464 dogs of all ages and both sexes. Identification was performed using morphological keys and data were analyzed using the Repeated Measures ANOVA, post-hoc Scheffe test and F test, relating independent variables as seasons and regions. Final results were translated to maps using GIS software. Five species of ticks were identified: Rhipicephalus pulchellus, Rhipicephalus sanguineus sensu lato (s.l.), Rhipicephalus armatus, Amblyomma gemma and Hyalomma truncatum. Our results suggest a statistical difference of the tick community structure related to seasonal and altitudinal distribution. Parasitism with R. armatus and R. pulchellus was higher in September-October than in January, whereas, R. sanguineus s.l. was not influenced by the season. Rhipicephalus armatus was present exclusively on dogs living in semi-desert areas, while R. sanguineus s.l. was the dominant species present on the shores of Lake Turkana. Although R. pulchellus was present in the all studied areas, this species had a significantly higher abundance in the afromontane region of Mt. Kulal and montane xeromorphic forest of Mt. Nyiru; these regions are characterized by elevated humidity and cooler climate. Similar geo-climatic distribution is typical also for A. gemma, which was found in dogs exclusively in Mt. Kulal afromontane area. The current work represents the most extensive study performed on the tick community structure of dogs in Eastern Africa. The results showed a relatively limited tick species diversity, with clear seasonal differences and altitudinal distribution.

A new species of sucking louse (Phthiraptera: Anoplura: Linognathidae) from Günther's Dikdik (Madoqua guentheri) in Kenya.

Linognathus samburi n. sp. is described from adult male and female specimens collected from a juvenile female Günther's dikdik (Madoqua guentheri) live-trapped near Olturot Village, Samburu district (Rift Valley Province) in northern Kenya. The new species is distinguished from other species of Linognathus including Linognathus geigyi and Linognathus damarensis, both of which parasitize Kirk's dikdik (Madoqua kirkii). A dichotomous key to the species of Linognathus that are known to parasitize dikdiks is included.

Relationship between the Prevalence of Ectoparasites and Associated Risk Factors in Free-Range Pigs in Kenya.

A cross-sectional study was undertaken to determine the prevalence of ectoparasites and possible risk factors in free-range pigs from 135 farms of Busia District, Kenya. Three hundred and six pigs were examined for presence of external parasites using standard parasitological methods. Data on management practices including housing and history of acaricide spraying were also collected. The ectoparasites found in the pigs were Haematopinus suis (96.1%), Sarcoptes scabiei (63.7%), and ticks (29.7%). The tick species included Rhipicephalus appendiculatus (70%), Boophilus decoloratus (31%), and Amblyomma variegatum (12%). The occurrence of the infestations was associated with age, being highest in sows (S. scabiei) and finishers (ticks and H. suis). Male pigs had highest prevalences of H. suis and ticks, while female pigs had highest prevalence of S. scabiei. The prevalence of the parasitic infestations was significantly (P < 0.05) associated with their origin being either lower (H. suis and S. scabiei) or higher (ticks) in pigs originating from divisions with high rainfall. Housed pigs had significantly (P < 0.05) lower prevalence of H. suis and ticks than those from households without pig housing. It is concluded that the free-range pigs have high prevalence of ectoparasites, and effective control strategies focussing on improved animal husbandry and acaricide use should be implemented.

Risk factors associated with occurrence of nematodes in free range pigs in Busia District, Kenya.

Nematode infections are a serious constraint to pig production, especially where free range pig keeping is practiced. This study investigated the epidemiology of nematodes in free range pigs in Busia District, Kenya. Three hundred and six pigs from 135 farms were sampled for faeces that were analysed for nematode eggs per gram (EPG) of faeces using the McMaster technique. The nematode eggs were also identified to genus and species based on morphology. A questionnaire on risk factors was also administered to the pig owners. The overall prevalence and mean nematode EPG were 84.2% and 2,355, respectively. The nematode eggs were identified as those belonging to Oesophagostomum spp. (75%), Strongyloides ransomi (37%), Ascaris suum (18%), Metastrongylus spp. (11%), Trichuris suis (7%) and Physocephalus sexalatus (3%). The prevalence of nematodes was positively correlated (p < 0.05) with the amount of rainfall in the division of the pigs' origin (all nematodes except S. ransomi). The prevalence of nematodes was also associated with the age of the pigs. A lower burden of nematodes was associated (p < 0.05) with a history of deworming (A. suum) and the provision of night housing (S. ransomi and Metastrongylus spp.). In conclusion, this study has provided information on nematode infections and the associated risk factors for free range pigs in Busia District, which can be used when implementing integrated control measures.

Occurrence of filaria in domestic dogs of Samburu pastoralists in Northern Kenya and its associations with canine distemper.

Samples of blood (serum, smears and blood preserved with ethanol) were collected from dogs during a vaccination campaign in northern Kenya in the years 2006 and 2007. Blood was screened for filarial parasites using molecular and microscopy methods and sera were tested for antibodies against canine distemper virus (CDV). Parasitological examination revealed the presence of two species of canine filariae: Acanthocheilonema dracunculoides and A. reconditum. The DNA from the former species was detected in 58% dogs sampled in 2006 and 36% dogs sampled in 2007, whereas the latter was found only in 4.2% samples collected in 2007. Microfilariae were found in 33.8% blood smears collected in 2006 and 10.6% blood smears collected in 2007. The seroprevalence of CDV was 33.4% in 2006 and 11.2% in 2007. The effect of sex, age and CDV-seropositivity/seronegativity on the occurrence of A. dracunculoides was evaluated. Infection by A. dracunculoides was more common in males and in dogs with a positive antibody titer for canine distemper, but evenly distributed among different age groups. The difference in the prevalence of A. dracunculoides in two isolated mountain ranges was not statistically significant. Methodologies available for detection and determination of canine filariae are compared, underlining methodical pitfalls arising through the determination of less common filarial species. The role of single epidemiological factors and possible association between canine distemper and filariasis are discussed.

Characteristics of the smallholder free-range pig production system in western Kenya.

Free-range pig farming is common amongst the small-scale farmers in western Kenya. In order to determine the characteristics of this type of production system, a cross-sectional questionnaire survey on farm characteristics and management was collected from 182 farmers in Busia District. The mean farm size was one acre, while the mean number of pigs per farm was 3.6. Pigs were mainly kept as a source of income (98%) and majority were of cross breed variety (64%). The production systems included farrow to weaner (12%), porker to finisher (36%), and mixed (46%). Sixty five percent (65%) of the pigs were tethered and housing was not provided in 61% of the farms. Most of the feeds were sourced locally. Lack of castration and delayed weaning of pigs was observed on 49% and 30% of the farms, respectively. The main production constraints included pig diseases (81%) and high cost or lack of feed (81%). Haematopinus suis infestations and worm infections were considered to be the most important diseases by 71% and 55% of the farmers, respectively. Farmers had moderate knowledge on parasitic disease diagnosis with 31% and 62% not having a history of either deworming or spraying pigs with acaricides, respectively. Marketing constraints were common amongst the farmers and included poor prices and inadequate market information. In conclusion, the production system was characterized as low-input with an income objective. Future research and development approaches should focus on the integration of free-range farmers into the country's market chains through access to extension services.

Evaluation of the recognition of Theileria parva vaccine candidate antigens by cytotoxic T lymphocytes from Zebu cattle.

East Coast fever (ECF) is a highly fatal lymphoproliferative disease of cattle caused by Theileria parva, a tick-borne intracellular apicomplexan parasite. Parasite antigens that are targets of protective cytotoxic T lymphocyte (CTL) responses are required to formulate a sub-unit vaccine against ECF. A number of CTL target antigens have recently been identified and initial evaluation has shown their vaccine potential. This study aimed to evaluate whether these antigens were recognised by CTL obtained from six genetically diverse Zebu cattle immunized with a cocktail of T. parva stocks. T. parva Muguga specific polyclonal CD8(+) CTL lines were generated and confirmed to specifically lyse autologous infected cells. CTL recognition of autologous skin fibroblasts (iSF) transduced with recombinant modified vaccinia virus Ankara strain (MVA) expressing previously identified T. parva Muguga vaccine candidate antigens was evaluated using an IFN-gamma ELISpot assay. CTL lines from one of the four calves, BY120, responded specifically to cells infected with MVA expressing the antigen Tp2 and synthetic peptides were employed to map a new CTL epitope on this antigen. Immunoscreening of the T. parva genome with these CTL lines should identify novel antigens that will constitute valuable additions to the vaccine candidates currently being evaluated.