Spatial clustering of fourteen tick species across districts of Zimbabwe.

BACKGROUND: Ticks transmit several diseases that result in high morbidity and mortality in livestock. Tick-borne diseases are an economic burden that negatively affect livestock production, cost countries billions of dollars through vaccine procurement and other disease management efforts. Thus, understanding the spatial distribution of tick hotspots is critical for identifying potential areas of high tick-borne disease transmission and setting up priority areas for targeted tick disease management. In this study, optimised hotspot analysis was applied to detect hotspots and coldspots of 14 common tick species in Zimbabwe. Data on the spatial distribution of tick species were obtained from the Epidemiology Unit of the Division of Veterinary Field Services of Zimbabwe. RESULTS: A total of 55,133 ticks were collected with Rhipicephalus decoloratus being the most common species (28.7%), followed by Amblyomma hebraeum (20.6%), and Rhipicephalus sanguineus sensu lato (0.06%) being the least common species. Results also showed that tick hotspots are species-specific with particular tick species occupying defined localities in the country. For instance, Amblyomma variegatum, Rhipicephalus appendiculatus, Rhipicephalus decoloratus, Rhipicephalus compostus, Rhipicephalus microplus, Rhipicephalus pravus, and Rhipicephalus simus were concentrated in the north and north eastern districts of the country. In contrast, Amblyomma hebraeum, Hyalomma rufipes, Hyalomma trancatum and Rhipicephalus evertsi evertsi were prevalent in the southern districts of Zimbabwe. CONCLUSION: The occurrence of broadly similar hotspots of several tick species in different districts suggests presence of spatial overlaps in the niche of the tick species. As ticks are vectors of several tick-borne diseases, there is high likelihood of multiple disease transmission in the same geographic region. This study is the first in Zimbabwe to demonstrate unique spatial patterns in the distribution of several tick species across the country. The results of this study provide an important opportunity for the development of spatially-targeted tick-borne disease management strategies.

Risk factors associated with clinical dermatophilosis in smallholder sector cattle herds of Zimbabwe at the Amblyomma variegatum and Amblyomma hebraeum interface.

A cross-sectional study was conducted to investigate factors for clinical dermatophilosis herd-level positivity in smallholder dip tanks from Gokwe (Chemawororo, Gwanyika), Kwekwe (Koronika) and Chegutu (Chivero), Zimbabwe, between September 2013 and April 2014. A total of 185 herds were clinically examined for disease and tick infestation. Data on herd and potential herd level risk factors were collected using a structured questionnaire. A herd was classified as clinically positive if an animal satisfied any of the following criteria: small lesions characterised by hairs clumping like a small paint brush, clear exudative circumscribed lesions with scabs of at least 1 cm in diameter and confluent progressive exudative scab lesions affecting significant parts of the animal's body. Amblyomma variegatum and Amblyomma hebraeum ticks were identified in situ with further laboratory confirmation. The potential herd-level risk factors for clinical dermatophilosis were tested using multiple logistic regression with herd infection status (positive, negative) being the binomial outcome and risk factors being predictors. Of the herds examined, clinical bovine dermatophilosis was detected in 45 % (84/185, 95 % confidence interval (CI) 38.2, 52.6 %) of the herds. The herd prevalence ranged from 6.9 % (95 % CI 0.00, 16.7) to 56.7 % (95 % CI 43.8, 69.6) with Chivero and Chemawororo dip tanks recording the lowest and highest prevalence, respectively. Herds infested with A. variegatum were associated with higher odds (OR = 6.8, 95 % CI 1.71, 27.10) of clinical dermatophilosis while the association was not significant (p > 0.05) in A. hebraeum-infested herds. A history of having bought cattle (OR = 3.5, 95 % CI 1.09, 11.12) compared to not buying was associated with increased herd clinical positivity status. It was concluded that management practices aimed at movement and tick control would help reduce the prevalence of clinical dermatophilosis in cattle herds.

Ethno-veterinary control of bovine dermatophilosis and ticks in Zhombe, Njelele and Shamrock resettlement in Zimbabwe.

A structured questionnaire survey was conducted to determine the ethno-veterinary practices and other control methods used by smallholder farmers for the management of bovine dermatophilosis and ticks. A total of 153 farmers were interviewed from Njelele, Zhombe communal and Shamrock resettlement areas. Crop production contributed most to livelihoods (83.2 %) while livestock contributed 9.0 %. Over 90 % of the respondents had attended school up to primary level, with 11.4 % undergoing animal health and husbandry training. Treatment of livestock diseases was practised by 96 % of the farmers, and 49.7 % of these farmers used ethno-veterinary medicines. Across the study sites, dermatophilosis was controlled using the following plants: Cissus quadrangularis (59.7 %), Catunaregam spinosa (10.5 %), Pterocarpus angolensis (10.5 %), Kalanchoe lanceolata (5.3 %), Aloe chabaudii (3.5 %), Cassia abbreviata (1.8 %), Dichrostachys cinerea (1.8 %), Urginea sanguinea (1.8 %), Ximenia caffra (1.8 %) and a plant locally called umfanawembila (1.8 %). Carica papaya and two plants, locally called mugimbura and umdungudungu, were used for tick control, and these were reported once from Njelele communal. Other control methods, besides plants or conventional drugs, were used by 28 % of the farmers for the treatment of dermatophilosis and ticks. Some farmers (14.4 %) claimed that ethno-veterinary medicines performed better than conventional drugs. The study revealed that farmers used ethno-veterinary medical practices for the treatment of dermatophilosis but rarely for tick control.