Esayas Gelaye

Evaluation of Deltamethrin applications in the control of tsetse and trypanosomosis in the southern rift valley areas of Ethiopia.

A study aimed at evaluating the efficacy of Deltamethrin (0.4% impregnated targets and 1% pour-on formulation) in controlling tsetse and trypanosomosis was carried out in two selected 10km x 10km Universal Transverse Mercator Grids of the Southern Tsetse Eradication Project (STEP) area in the southern rift valley of Ethiopia. The Grids selected were H3 (site I) and G5 (site II) in two districts of the Wolaita Zone. The trial was underway from September 2003 to April 2004. The strategy followed to accomplish the trial was a pre-intervention phase (entomology and parasitology) and an intervention phase with insecticide (Deltamethrin 0.4%)-impregnated odour-baited targets in site I and Deltamethrin 1% pour-on application to cattle in site II. The intervention phase was monitored on a monthly basis. Following the deployment of 460 targets at a density of 4 targets per km(2) in trial site I, the relative abundance of tsetse fly (Glossina pallidipes) declined from a pre-intervention mean catch of 1.35 flies per trap per day to 0.05 flies per trap per day at final monitoring. These resulted in an 88.9% overall reduction. Similarly, an 83.25% reduction was recorded in the incidence of trypanosomosis in sentinel cattle as it dropped from 10.75% (first monitoring) to 1.8% (last monitoring). The corresponding measures of packed cell volume (PCV) have shown a significant improvement from a mean of 21.8% (95% confidence interval (CI): 20.7-22.9) at first monitoring to 25.5% (95% CI: 24.3-26.7) of last monitoring (P<0.01). In site II, the trial was started by spraying Deltamethrin 1% pour-on to 409 cattle at a rate of 1ml/10kg body weight. Pour-on treatment was repeated every month throughout the trial period. A sharp drop in the relative abundance of tsetse fly was revealed soon after. The catch was nil at fourth monitoring as it declined from 0.91 flies per trap per day of pre-intervention (P<0.01). A 94.9% overall reduction was achieved. The incidence of trypanosomosis in sentinel cattle also declined from 10% (first monitoring) to 0.95% (last monitoring) with about 90.5% decline. An improvement in the overall mean PCV was seen as it rose from a mean of 24.1% (95% CI: 22.9-25.3) at first monitoring to 27.2% (95% CI: 26.2-28.1) at last monitoring which revealed a significant increase (P<0.01) until the third monitoring and maintained a stable state thereafter. This work finally disclosed that a relatively better efficacy was attained by using Deltamethrin pour-on formulation than targets in controlling tsetse and trypanosomiosis. However, this difference did not prove an apparent significance (P>0.05). So it is recommended to continue the current tsetse suppression by using the integrated approach of both techniques under consideration.

Study on seroprevalence, risk factors, and economic impact of foot-and-mouth disease in Borena pastoral and agro-pastoral system, southern Ethiopia

Cross-sectional serological study and questionnaire survey were conducted in Borana pastoral and agro-pastoral area to determine seroprevalence and risk factors associated with foot-and-mouth disease (FMD) infection and to assess community perceptions as to importance of the disease. A multistage random sampling was carried out to select cattle for seroprevalence and households for interviews. Totally, 768 sera were collected from 111 herds. The overall individual level seroprevalence of 23.0% (nu2009=u2009177) and herd level seroprevalence of 58.6% (nu2009=u200965) were recorded using 3ABC ELISA test. The variation of individual level seroprevalence in districts were statistically significant (Pu2009<u20090.05) which was 29.9% in Arero, 24.0% in Yabello, and 15.7% in Teltele. From multivariate logistic regression analysis, herd size and age were seen to be significantly (Pu2009<u20090.05) associated with FMD seroprevalence. The result of the questionnaire survey based on 120 respondents indicated that, the daily milk yield of cows infected with FMD during outbreaks is reduced to an average of 0.5xa0L for 25.5xa0days while cows developing heat-intolerance syndrome after acute infection gave an average 0.67xa0L for 3.8xa0months and their calving interval prolonged about 12xa0months. The questionnaire survey in agro-pastoral area of Borena also indicated that FMD-infected oxen remained off-plough for one season when outbreaks occur in cropping time, whereas heat-intolerant oxen were no longer used for traction. These findings of the present study indicated that FMD is a highly prevalent and economically important disease in the Borana pastoral and agro-pastoral production systems which need effective control strategy for the disease.

Lumpy skin disease: Preliminary vaccine efficacy assessment and overview on outbreak impact in dairy cattle at Debre Zeit, central Ethiopia

This study was conducted in and around Debre Zeit town to assess the field efficacy of LSD vaccine in use and overview associated disease impact. The study comprised cross-sectional and retrospective study design which employed active disease follow-up, semi-structured questionnaire survey and molecular techniques. The finding revealed that the Kenyan sheep pox vaccine strain used for the control of LSD did not confer expected protection. From the total of 476 animals observed, 22.9% and 2.31% cattle were found sick and dead due to LSD, respectively. Breed specific morbidity rate was 22.5% in Holstein Friesian-zebu cross and 25.9% in local zebu breed. The disease was observed to be more serious in young animals and also in females. A trend of seasonality was also observed in its occurrence. The study finding urges the need for investigation of vaccine failure including vaccine matching and alternative vaccine development.

A study on seroprevalence of caprine brucellosis under three livestock production systems in southern and central Ethiopia

Caprine brucellosis in Ethiopia is less commonly reported with limited information on the disease status in the country. The objective of this study was therefore to highlight the status of goat brucellosis in three distinctly different livestock production systems of southern and central Ethiopia. A total 3,315 goats of different age and sex, living with other animals in variable flock size, were sampled from 448 flocks raised in sedentary, pastoral and agro-pastoral production systems. Goats were bled aseptically and sera were collected for serial testing using Rose Bengal Plate Test as screening test and subsequently complement fixation test as confirmatory test. Questionnaire and laboratory data were analysed for descriptive, univariable and multivariable logistic regression analysis both at individual and flock level (STATA 11). The study revealed an overall animal level seroprevalence of 1.9xa0% (95xa0% CI 1.5, 2.4). In sedentary production system, the observed seroprevalence was 0.6xa0% (95xa0% CI 0.2, 0.9) while 1.9xa0% (95xa0% CI 1.1, 2.7) and 7.6xa0% (95xa0% CI 5.1, 10.1) were the proportion of seroreactors for agro-pastoral and pastoral production systems, respectively. The observed prevalence difference between the three production systems was statistically significant (Pu2009<u20090.05). At the flock level analysis, 11.2xa0% (95xa0% CI 8.2, 14.1) of the flocks sampled had at least one seropositive goat among themselves. Like individual level analysis, the highest prevalence of 32.5xa0% (95xa0% CI 21.9, 43.0) was recorded for pastoral production system, followed by agro-pastoral, 13.0xa0% (95xa0% CI 7.0, 19.0) and sedentary production system, 3.6xa0% (95% CI 1.3, 6.0). Accordingly, the odds of Brucella seropositivity were higher (ORu2009=u200912.8) in pastoral followed by agro-pastoral (ORu2009=u20094.0) in relation to sedentary production system. Large numbers of seroreactors were observed in adult age living in larger flocks with other livestock species. However, no difference was noted between male and female goats. Finally, the need for nationwide survey and subsequent designing and implementation of appropriate control measure is suggested.

Serological survey of African horse sickness in selected districts of Jimma zone, Southwestern Ethiopia

A cross-sectional serological survey was undertaken in selected districts of different agro-ecology of Jimma zone (Dedo, Yebu, Seka, Serbo, and Jimma town) from November 2009 to February 2010 to determine the seroprevalence of African horse sickness virus and associated risk factors of the disease. Two hundred seventy-four equids (189 horses, 43 mules, and 47 donkeys) with a history of non-vaccination for at least 2xa0years were selected randomly from the above areas. Sera samples were collected and assayed for the presence of specific antibody against African horse sickness virus using blocking ELISA. An overall seroprevalence of 89 (32.5%) was found and it was 24 (51.1%) for donkeys, 13 (30.2%) for mules, and 52(28.3%) for horses. Seroprevalence was significantly (X2u2009=u200911.05, Pu2009<u20090.05) different among the different species of equids. Seroprevalence was also significantly (X2u2009=u200911.43, Pu2009<u20090.05) different among the different agro-ecological areas being higher in highlands 47 (40.5%) followed by midland 30 (34.5%) and lowland 12 (16.9%). Age and sex were not significantly (X2u2009=u20093.15, Pu2009>u20090.05 and X2u2009=u20093.38, Pu2009>u20090.05, respectively) associated with seroprevalence of AHSV. The present study showed that African horse sickness (AHS) is highly prevalent disease for the horses followed by mules and then donkeys in Jimma zone explained by lower seroconversion rate. Therefore, control strategy against AHS should target at high risk species of all age and sex in their locality in the initial stage for better containment of the disease.

FMD virus isolates: The candidate strains for polyvalent vaccine development in Ethiopia

The study was conducted on foot-and-mouth disease (FMD) viruses with the aim of selecting appropriate vaccinal strain to control of FMD in Ethiopia. The study was conducted in two-dimensional virus neutralization assay to determine the antigenic relationship r value between the candidate vaccine strains and field isolates. A total of 21 serotype O, 7 serotype A, and 8 serotype SAT 2 FMD viruses, which were isolated from cattle and swine. A couple of isolates from each serotype were identified as vaccine candidates in the trial (O-ETH/38/2005, O-ETH/58/2008, A-ETH/7/2008, A-ETH/6/2000, SAT2-ETH/76/2009 and SAT2-ETH/64/2009). The finding revealed all the vaccine candidate depicted high antigenic similarity, above the mean r value, to their own serotypes in the studied serotype population except for one serotype A field isolate, A-ETH/13/1981, with r value=0.14 and 0.25) which is significantly lower than the minimum requirement. In general, the result indicated that these candidate vaccinal strains can be used for polyvalent vaccine production in the country.

Infectious bursal disease: seroprevalence and associated risk factors in major poultry rearing areas of Ethiopia

The study was conducted in eight districts of Ethiopia with the objectives of determining the seroprevalence and associated risk factors of infectious bursal disease (IBD). From the total of 2,597 chicken serum samples examined using ELISA, 83.1xa0% were found positive. The highest seroprevalence was found at Mekele (90.3xa0%) while the lowest was recorded at Gondar district (69.8xa0%). These differences among the study areas were statistically significant (pu2009<u20090.05). Highest seroprevalence was found in crossbreed of chicken (91.4xa0%) while the lowest was recorded in indigenous breed of chicken (81.4xa0%). This difference was statistically significant (pu2009<u20090.05) among the three breeds of chickens, but sex was not statistically significant (pu2009>u20090.05). The seroprevalence of the disease was found high in young (≤8xa0weeks) age group (86.6xa0%) while the lowest prevalence was recorded in adults (>8xa0weeks) (72xa0%). This is also statistically significant (pu2009<u20090.05) between young and adult age groups. The prevalence of IBD in different production system indicated that higher seroprevalence was recorded in intensive production system (85.9xa0%) while the lowest was recorded in extensive production system (81.6xa0%). This difference is also statistically significant (pu2009<u20090.05).

Genetic characterisation of infectious bursal disease virus isolates in Ethiopia

Graphical abstract This paper describes a molecular characterisation of IBD circulating in commercial and breeding poultry farms in Ethiopia. Ethiopian vvIBDVs are clustered phylogenetically with the African IBDV genetic lineage, independent of the Asian/European genetic.

Outbreak investigation and molecular characterization of African horse sickness virus circulating in selected areas of Ethiopia.

The study was conducted from June 2011 to May 2012 in central, northern and western parts of Ethiopia to investigate and identify circulating serotypes of African horse sickness virus (AHSV). The indigenous knowledge of equine owners about AHS in the study areas was assessed and also the retrospective data of AHS outbreaks for 2011 were analyzed. Whole blood samples were collected for virus isolation and serotyping from diseased horses and mules showing typical signs of the AHS. Virus isolation on Vero cell and detection of AHSV genomes using conventional RT-PCR were conducted. Further molecular characterization and serotyping were done on positive isolates. The questionnaire survey revealed that equine owners do recognize AHS clinically and have a local name that varies in different regions. From the 72 equine owners interviewed about their knowhow of AHS, 48 (66.7%) of respondents were not aware of AHS disease mode of transmission. The retrospective disease report data showed that a total of 208 outbreaks were reported and 3036 cases and 1167 deaths were recorded in 2011. AHS outbreaks were more frequently observed from September to December and the highest number of outbreaks was recorded in October. During the study period totally six outbreaks were investigated and a total of 62 horses and 10 mules were found sick and all the four forms of AHS were observed. Cardiac form accounted for 52.8%, followed by African horse sickness fever form 31.9%, pulmonary form 8.4% and mixed form 6.9%. AHSV-9 was the only serotype circulating in the outbreak areas.

The first isolation and molecular characterization of camelpox virus in Ethiopia.

A cross-sectional study was conducted from November 2011 to April 2012 in Chifra district of Afar and in Jigjiga Zone of Somali Regional States of Ethiopia with the aims of assessing the epidemiology of camelpox and isolate and molecularly characterize the virus. The study included a questionnaire, active disease search and virus isolation and sequencing. A total of 24 (4.50%) and 12 (3.0%) camels in Afar and Jigjiga respectively were found clinically sick of camelpox during the study period. The questionnaire survey indicated that camelpox is the most common disease in the areas in which 125 (96%) of the respondents reported the frequent occurrence of camelpox in their herds especially during rainy season. The PCR result revealed 12 out of 17 tested samples were positive, of which seven of them collected from Jigjiga zone showed the characteristic PCR positive bands of 881 bp size fragments while five of the Afar samples gave two faint bands. Ethiopian isolates, specially isolated from Somali have very high identity with comparable sequences of CMLV M-96 from Kazakhstan and CMLV CMS from Iran. Out of the total of 780 bp analogous sequences, Ethiopian isolates differ only in two positions, while CMLV-Teheran differed at four nucleotide positions. The successfull isolation and molecular characterization of camelpox virus in Ethiopia, which could help for early diagnosis and control of the disease in the country.