Study sites: Saahil and Togdheer regions of Somaliland Figure 1
The study was carried out in the two administrative Saahil and Togdheer regions of Somaliland from (10 November to 21 December 2019 (dry season) and 06 June to 11 July 2021 (rainy season) between latitudes of (10.88686° -10.501362° ) E, longitudes (45.43265° -44.823402° ) W and an elevation/altitude of between 2m-876m above sea level for Saahil region, and between latitudes of (9.811323° -9.633420° ) E, longitudes of (46.114562° -45.360693° ) and an elevation/altitude between 932m to 1229m above seas level for Togdheer region. Generally, Saahil region is rocky and mountainous, mostly sandy in the coastal area with sparse vegetation and hot with temperatures between 28-32℃ on averages which reaches 40℃ in coastal areas, while Togdheer region relatively less mountainous, mostly green plateau with relatively high density of shrubs, grass land and different trees with an average temperature of between (17-29 ℃). The lowest value in the country’s Relative humidity of about (40%) occurs within Togdheer region. Wind speed ranges between 8 to 11 meters per second in June July at areas of Toghdeer region Somalia Water and Land Information Management (SWALIM) (2007). But these meteorological parameters usually change season by season.
Animals graze during the rainy season when temperatures are relatively low 15-25°C and move within coastal areas from place to place depending on vector challenge during rainy seasons. Animals however move to highland areas in Togdheer region when the climate becomes too hot and windy in Saahil tregion. Noteworthy is that the spring (rainy season) of 2021 was too short compared to normally known pattern. By late May rains stopped.
Sampling Design: A stratified random sampling technique was used in order to get optimal representation of the expansive administrative regions. In each administrative region, three clusters were stratified based on their proximity to urban centers with animal health infrastructure, most commonly the district headquarters. The study sites (villages) within 20 km of the regional headquarters (Berbera for Saahil and Burao for Togdheerare considered to form cluster one, those within 20-50 km of the regional headquarters form cluster two while those that are more than 50km from the regional headquarters form cluster three. Three study sites (locations/settlements) have been randomly selected from each cluster, for a total of 9 sites in each region conditions permitting. Selected villages were geo-referenced. Locations where livestock owners reject cooperation will be replaced with the nearest location possible.
Sample size determination: In each cluster locations, a random sampling technique has been used to recruit animals for the study after the approval of the owners. The sample size was calculated as recommended by (Thrusfield 2005), assuming an expected prevalence of 50%, a 5% absolute precision and 95% confidence interval. Therefore, the calculated sample size was 386 camels. The number of animals to be sampled was distributed to the three sampling clusters based on the estimated population of animals in each village and location.
Examination of selected animals: At each selected site, information on the livestock keeper’s details (name, address, and where practical, phone number and herd characteristics (herd size, numbers of adult males, females and young stock) were collected followed by documentation of detailed case histories for all camels selected for veterinary examination and sampling. Complete records of these data are kept for subsequent analysis. Estimation of body weight and body condition score was carried out by visual appraisal. In addition, discussions were held with the elders and pastoralists on their knowledge on the disease, its causes and the vectors. Camel herd compositions were visually estimated, because culturally pastoralists are reluctant to provide information on herd size as this considered a sensitive matter and are reluctant to share such information with strangers. Camels below 2 year were considered as calves, those between 2-4 years as young, while those above 4 years of age were considered adults.
Blood sample collection: Blood samples were collected for confirmatory diagnosis. A total of 5 ml of blood was collected from the jugular veins of all selected camels using Ethylenediaminetetraacetic acid (EDTA) vacutainer tubes. The whole blood in EDTA sample was divided into two aliquots, each 2.5 ml. One of the 2.5 ml aliquot was used for parasitological examination (PCV) determinations. Parasitological examinations were carried out using a combination of Gram stained thin and thick blood smears (TTBS) after concentration of trypanosomes by the micro-haematocrit centrifuge technique (MCHC) recommended by (Woo 1969) and a direct Gram stained wet (TTBS) without concentration. Animals with (PCV) < 25% were considered anemic as recommended by (Gerem et al. 2020).
Setting NZI Traps: A total of 62 (33 and 29) traps and 64 (34 and 30) traps were set up in the six clusters of Saahil and Togdheer in first and second phase respectively. Traps were set and emptied 48 hours post setting. Three weeks old cow urine was used as attractant. Grease was applied at the bottom of the pole to prevent attack from predator insects.
Data analysis: Data was analyzed using Jamovi 1.2.27 statistical software. Tabular data were exported to Microsoft word tables. And figures were created using Jamovi 1.2.27 statistical software.
Biting flies were classified and identified up to genera level using the three volumes of
Oldroyd, H. (1952) The horse-flies (Diptera: Tabanidae) of the Ethiopian Region. Volume I. Haematopota and Hippocentrum. British Museum Natural History
Oldroyd, H. (1954) The horse-flies (Diptera: Tabanidae) of the Ethiopian Region. Volume II. Tabanus and related Genera. British Museum Natural History
Oldroyd, H. (1957) The horse-flies (Diptera: Tabanidae) of the Ethiopian Region. Volume III. Subfamilies. And Stereomicroscope model GX CEROHSFC