| dc.description.abstract | Mange is a contagious skin disease caused by one or a combination of several species of mites and is spread by direct contact with diseased animals or from various objects, which have been in contact with the diseased animals. The various species of mites affect domestic animals, humans and wildlife and mange is a disease of zoonotic importance. A study was carried out in Masai Mara ecosystem to determine the spatial distribution and prevalence of mange, establish the level of knowledge of the disease dynamics of mange among pastoralists and wildlife officers, phenotypically and genotypically characterise the mange mites and determine relationship between the specific species found in various animal hosts. For the spatial distribution study, a cross-sectional survey was used to collect data of mange-like skin lesions over a period of 2 years in cheetahs, Thomson's gazelle, sheep, goats, cattle, dogs and other wild animals.
The study area was divided into 8 study blocks, 3 within the protected area and 5 in the community ranches. Global Positioning System (GPS) co-ordinates and dates of observation of all individual animals and/or herds observed to have clinical signs of mange were recorded. Maps of distribution were generated using Arc View software for Global Information System (GIS) mapping. Infected animals were observed in 6 out of the 7 study blocks where the study was carried out. There was a higher concentration of infected animals along the boundaries of protected areas and community ranches where there is significant interaction between wildlife and domestic animals. There was a higher concentration of infected animals in dry than in wet season.
In the prevalence study, a cross-sectional survey was used to collect data of mange-like skin lesions over a period of 2 years in cheetahs, Thomson's gazelle, sheep, goats, cattle, dogs and wildebeest. Purposive random sampling method was used to get the sampling units. Sampling of domestic animals was based on study blocks closer to the protected areas or where cheetahs were known to occur, while Thomson's gazelle sampling was based on study blocks within the protected areas and in community ranches where they occur. Due to their low numbers and very large home ranges, cheetahs were sampled opportunistically. The prevalences of mange-like skin lesions were: cheetah 12.77% (n=47), dogs 4.67% (n=279), Thomson's gazelle 0.81% (n=10,788), sheep 0.76% (n=6,699), cattle 0.09% (n=2,311), goats 0.09% n=1,174) and wildebeest 2.00% (n=50).
The factors that can affect prevalence of mange in the study area were identified as geographical location (study blocks), climatic season and time of sampling. There was a higher prevalence in study blocks that had high wildlife/livestock interaction, in dry than wet climatic season and in the year 2007/2008 than 2008/2009. However, it was only among Thomson's gazelles that the difference between prevalence in dry and wet season and between the first and second year of sampling was significantly different (P = 0.0001). The study to establish the level of knowledge of the disease dynamics was conducted using pre-tested questionnaires.
Fifty six pastoralists and 30 wildlife officers responded. Ninety three (93%) percent of past ora lists and 99.7% of wildlife officers stated that they had come across mange while 23.3% and 66.1 % of the pastoralists and wildlife officers knew that the disease is caused by mites. Up to 70% of respondents in the 2 groupS thought that the disease is transmitted from domestic to wild animals and vice versa. Over 80% of respondents from both groups confirmed that they had seen infected animals. Sixty eight (68%) percent of past ora lists confirmed they normally treated and initiated control measures against mange, with application of acaricides being most preferred. Pastoralists identified fungal diseases, sheep and goat pox, papillomatosis and phosensitization as skin diseases that can be confused with mange while wildlife officers identified lumpy skin disease, fungal infections and giraffe ear infection.
This study concluded that there was a lot of information about mange among pastoralists and wildlife officers within the ecosystem but more studies using Participatory Rural Appraisal (PRA) approach were required to determine if the disease they identified was mange. Phenotypic characterization studies were conducted on 78 samples collected from different species of wild and domestic animals with skin lesions. The clinical picture in the field was that of alopecia, pruritus, acute dermatitis, suppurative encrustation, skin roughening and poor body condition. Mites were identified in the laboratory through microscopy. The positive samples with respect to animals showing skin conditions were as follows: cheetahs 100% (S/S), Thomson's gazelle SO% (S/10), sheep 52.9% (27/51), dogs 11.1% (119), wildebeest 100% (5/5) and lions 100% (2/2). Samples from cattle goat and impala were negative. Sarcoptes scabiei was isolated from all the animals except sheep where Psoroptes communis was isolated. The study revealed that sarcoptic mange is the commonest mange affecting wildlife in the Masai Mara ecosystem.
Genotypic characterization study was undertaken through use of molecular techniques. Deoxy-ribonucleic acid (DNA) was extracted from individual mites isolated from the various host species and subjected to Fluorescent-based polymerase chain reaction (peR) analysis of micro satellite DNA. There was genetic diversity of mites of S. scabiei isolated from the same host species with the highest diversity observed in wildebeest and cheetahs and lowest in Thomson's gazelle and lion. Genetic similarities were observed between mites isolated from cheetahs and wildebeest, cheetah and Thomson's gazelle, cheetah and lion, and lion and wildebeest. The similarity was attributed to gene flow of mites as a result of predator-prey relationship and host-taxon-derived effect for cheetah and lion. The study showed that there is intra-host differences and inter-host genetic similarity of Sarcoptes mites among wildlife in Masai Mara ecosystem.
In conclusion, the spatial distribution of mange infected animals was found to be related to areas with close interaction between wild and domestic animals and climatic seasonal changes. The prevalence of mange in free-ranging cheetah and Thompson's gazelle is reported for the first time in literature. Sarcoptes scabiei was found to be the commonest cause of mange in wild animals while P. communis was the commonest in sheep within the ecosystem. There was also intra-host genetic differences and inter-host genetic similarities of Sarcoptes mites among wild animal hosts in Masai Mara ecosystem. There was also detection of host-taxon effect in Sarcoptes mites of genetically related species. This study has shown a Sarcoptes gene flow in predator/prey system, which is of pivotal interest for sarcoptic mange control and wildlife conservation. | en_US |
