Biogeography of the theileriosis vector, Rhipicephalus appendiculatus under current and future climate scenarios of Zimbabwe.

Climate directly influences the epidemiology of vector-borne diseases at various spatial and temporal scales. Following the recent increased incidences of theileriosis in Zimbabwe, a disease mainly transmitted by Rhipicephalus appendiculatus, we determined lethal temperatures for the species and current and possible future distribution using the machine learning algorithm 'Maxent'. Rhipicephalus appendiculatus larvae had an upper lethal temperature (ULT50) of about 44 ± 0.5 °C and this was marginally higher for nymphs and adults at 46 ± 0.5 °C. Environmental temperatures recorded in selected zonal tick microhabitats were below the determined lethal limits, indicating the ability of the tick to survive these regions. The resultant model under current climatic conditions showed areas with high suitability indices to the eastern, northeastern and southeastern parts of the country, mainly in Masvingo, Manicaland and Mashonaland Central provinces. Future predictions as determined by 2050 climatic conditions indicate a reduction in suitable habitats with the tick receding to presently cooler high elevation areas such as the eastern Highlands of Zimbabwe and a few isolated pockets in the interior of the country. Lowveld areas show low suitability under current climatic conditions and are expected to remain unsuitable in future. Overall, the study shows that R. appendiculatus distribution is constrained by climatic factors and helps identify areas of where occurrence of the species and the disease it transmits is highly likely. This will assist in optimizing disease surveillance and vector management strategies targeted at the species.

Bovine brucellosis and tuberculosis at a livestock-wildlife interface in Zimbabwe: A nexus for amplification of a zoonosis or a myth?

BACKGROUND: Bovine brucellosis and tuberculosis are important zoonoses affecting both livestock and wildlife. OBJECTIVES: The study aimed to investigate seroprevalence of brucellosis and to isolate Brucella spp. and Mycobacterium bovis in cattle from livestock-wildlife interface areas. METHODS: Three sites were selected from high, medium and low interface. The high interface was adjacent to the park and separated by a broken fence, while the medium and low interface were 15-20 and 50 km from the perimeter fence, respectively. Cattle aged ≥2 years were randomly selected and bled for serology. Culture for brucellae and Mycobacterium species was attempted on lymph nodes collected at the slaughter floor. Sera were screened for Brucella antibodies using the Rose Bengal test and confirmed by the Complement fixation test. Data were analysed using a multivariable logistic regression model. RESULTS: Overall, seroprevalence was 11.7% (125/1068; 95% CI: 9.8-13.6%). High interface areas recorded significantly higher (p < 0.05) seroprevalence of 20.9% (85/406; 95% CI: 17.0-24.9%), compared to low 8.9% (31/350; 95% CI: 5.9-11.8%) and medium interface 2.9% (9/312; 95% CI: 1.0-4.8%). Brucella seropositivity was approximately three times higher (OR = 3.3, 95% CI: 2.1-5.3) for Malipati compared to Chiredzi. Similarly, the odds were twice (OR = 2.0, 95% CI: 1.2-3.5) in cows with history of abortion compared to those without. Brucella and Mycobacterium species were not isolated from all samples. CONCLUSIONS: The study highlighted the significance of high interface as a nexus for amplification of brucellosis in cattle. Thus, a brucellosis control programme that takes into consideration limiting livestock-wildlife interaction should be considered.

Prevalence of Campylobacter Species on Cattle Breeding Farms in Zimbabwe.

Infertility remains a challenge in breeding herds in most developing countries. In the current study, 104 penile sheath washes were collected from bulls of different breeds and ages from different cattle breeding farms in Zimbabwe. The samples were submitted to the Central Veterinary Laboratory, Zimbabwe, for screening of Campylobacter species using the polymerase chain reaction (PCR). Based on the PCR results, the animal-level prevalence was 25.96% (range 0-73.98%) and all the positive samples came from four (57.14%) of the 7 herds tested. The current study shows that Campylobacter spp. could be a causative agent in infertility observed in a number of herds in Zimbabwe. Strategies for treatment and control of campylobacteriosis should be enhanced in the country. More research and surveillance are needed to determine the epidemiology of Campylobacter species in Zimbabwean cattle herds.

Microbial quality of frozen Nile crocodile (Crocodylus niloticus) meat samples from three selected farms in Zimbabwe.

Microbial quality of frozen Nile crocodile (Crocodylus niloticus) meat from three farms in Zimbabwe was assessed based on 2051 samples collected for pre-export testing during 2006 to 2011. Data were perused by season and year in terms of aerobic plate (APC), coliform (CC), Escherichia coli (ECC) and Listeria monocytogenes (LMC) counts and the presence of Salmonella spp. The log10-transformed data were compared among the farms and seasons using the Kruskal-Wallis test. Microbial quality of the samples was graded based on the EC No. 2073.2005 criteria for beef. The mean APC and CC for the crocodile meat differed significantly (P=0.000) among the farms with the highest APC (3.2±0.05 log10 cfu/g) and the lowest (2.7±0.05 log10 cfu/g) recorded from farms A and C, respectively. There were no significant differences (P>0.05) in ECC and LMC among the farms, while Salmonella spp. were only isolated from one farm. Although the microbial quality of frozen crocodile meat from these farms was generally within acceptable limits, the isolation of E. coli and Salmonella spp. is of public health concern. Thus, implementing of measures to control the pasteurizing process and to minimize bacterial contamination of crocodile meat after pasteurization need to be carefully considered.