Lumpy skin disease in cattle in central Ethiopia: outbreak investigation and isolation and molecular detection of the virus.

The study was a combination of two investigations into active outbreaks of lumpy skin disease (LSD) in cattle in central Ethiopia and a retrospective analysis of outbreak reports between January 2007 and December 2011 covering the entire country. Active outbreaks were investigated in four districts of central Ethiopia: Adama, Wenji, Mojo and Welenchiti. A semi-structured questionnaire was used to acquire data at individual and herd levels, and tissue samples were collected for viral isolation and characterisation. The retrospective analyses showed that, during the five-year period, a total of 1,675 outbreaks were reported, with 62,176 cases and 4,372 deaths. The highest number of outbreaks was reported in Oromia (1,066), followed by Amhara (365) and the Southern Nations, Nationalities and People's Region (123). Outbreaks were more frequently observed between September and December and the highest number of outbreaks was reported in 2010. During the period studied, a total of 2,174 local zebu cattle were clinically examined and morbidity and mortality rates of 13.61% (296) and 4.97% (108) were recorded, respectively. Analysis of the active outbreaks revealed a relatively consistent morbidity rate, with the highest observed in Adama (15.38%), followed by Wenji (10.26%). The highest mortality rates were also observed in Adama (5.89%) and Wenji (3.42%). The LSD virus was isolated from 22 samples and all tested positive in polymerase chain reaction analysis. The disease was observed in the cattle regardless of previous vaccination with Kenyan sheep- and goat-pox vaccine; thus, vaccine efficacy was assessed under field conditions and the authors' findings, together with a possible remedy, are presented in this paper.

Reproductive disorders in relation to Neospora caninum, Brucella spp. and bovine viral diarrhoea virus serostatus in breeding and dairy farms of central and southern Ethiopia.

Abortion and stillbirth are important reproductive disorders in the dairy industry and are often caused by infectious agents. This study investigated whether bovine viral diarrhoea virus (BVDV), Brucella spp., and Neospora caninum are associated with abortion and/or stillbirth in dairy cattle in Ethiopia. Dairy cattle from 99 farms were categorized as cases (n=134) or controls (n=268) according to reproductive data. Blood samples were screened for antibodies for these infectious agents. The overall proportion of cattle that were seropositive for BVDV, Brucella spp., and N. caninum was 11∙7%, 3∙2%, and 17∙2%, respectively. Seropositivity for BVDV and Brucella spp. was similar for cases and controls, but significantly more cases were seropositive for N. caninum (29∙8%) than controls (10∙8%). This is the first report demonstrating N. caninum is common in dairy cattle in Ethiopia, and is probably a greater impediment to reproductive success in Ethiopian dairy farms than either BVDV or Brucella spp.

Study on the epidemiology of foot and mouth disease in Ethiopia.

This study was designed to describe the status of foot and mouth disease (FMD) in Ethiopia, through analysis of FMD outbreak reports and the detection of antibodies, to address the possibility of establishing a disease-free zone. Serum samples collected from cattle between 2003 and 2006 for the serosurveillance of rinderpest were used for this study. The records of the Ministry of Agriculture and Rural Development from 2002 to 2006 indicate that FMD outbreaks occurred each year in Ethiopia during this period, with the highest number in 2004, when 134 outbreaks took place. The highest rates were from the North Shoa zones of both the Oromia and Amhara regions. The serum samples were tested using the 3ABC enzyme-linked immunosorbent assay kit, to identify antibodies against FMD. From a total of 4,465 sera, 10.5% (n = 467) tested positive. The highest seroprevalence was detected in samples from the Eastern zone of Rgray with 41.5%; followed by the Guji zone of Oromia and Yeka district of the city of Addis Ababa, with 32.7% and 30%, respectively. Antibodies specific to FMD virus were not detected in Gambella or Benishangul. The effects of cattle, sheep and goat density, both separately and together, were analysed with a spatial regression model, but did not have a significant effect on seroprevalence. This indicates that other factors, such as farming systems and livestock movement, play a significant role in the occurrence of FMD. Based on these study findings, it might be appropriate to establish disease-free zones in Gambella and Benishangul.

Molecular identification of Neospora caninum from calf/foetal brain tissue and among oocysts recovered from faeces of naturally infected dogs in southern Ethiopia.

This study sought to confirm and investigate further recently published information regarding the occurrence of Neospora caninum in cattle in Ethiopia and investigate infection in dogs, the canine definitive host, in this region. Faecal samples from 383 dogs in Hawassa, Ethiopia were examined by microscopy for Neospora-like oocysts, and positive samples then analysed by a molecular approach (DNA isolation, PCR and sequencing at the ITS1 gene). Brain tissue samples from four late term aborted foetuses, one congenitally defective calf (hind leg arthrogryposis) and placental tissue from cattle in the same area were also examined by the same molecular approach. All foetal, calf and placental tissue were associated with Neospora seropositive dams. A high prevalence of Neospora-like oocysts (11.5 µm±1.5 µm diameter) was observed in faecal samples from dogs (37 positive samples; 9.7% prevalence), and in 17 of these the identification was confirmed by PCR, giving a prevalence of confirmed infection of 4.4%. N. caninum DNA was also detected in all foetal and calf brain tissue samples. Sequencing revealed only minor differences among all PCR products, whether from oocysts or from brain tissue samples. These data provide molecular evidence of the presence of N. caninum infection in both dog and cattle in this region of Ethiopia. Moreover these findings highlight the role of dogs in maintaining and spreading the infection horizontally in the study area. The high frequency of N. caninum infection in household dogs as well as farm dogs is worthy of further investigation.

Seroprevalence of Neospora caninum and associated risk factors in intensive or semi-intensively managed dairy and breeding cattle of Ethiopia.

A cross-sectional study of Neospora caninum infection was conducted in major milksheds of Ethiopia. Cattle (n=2334) from 273 farms were bled and the sera screened for antibodies against N. caninum using a commercial ELISA kit. Herd and individual animal level data were collected from farm records and a semi-structured questionnaire format. The overall animal level seroprevalence was 13.3%, while the prevalence at farm level was 39.6%. In urban and peri-urban smallholder dairy farms, the seroprevalence was 14.9%, while 12.9% and 9.8% reactors were found among commercial dairy farms and breeding cattle, respectively. At farm level, 35.7% of urban and peri-urban farms, 47.5% of the commercial farms and five of the breeding farms were found to have at least one infected animal. Purchased cows (OR: 2.3) and cows with history of maternal reproductive disorders (OR: 2.1) were associated with seropositivity at the individual animal level. Crossbred cattle (Holstein-Friesian crossed with indigenous zebu) were associated with lower risk than pure breeds (OR: 0.6). A trend of prevalence increment was observed for large herd sizes (OR: 1.8). Other factors that were associated with seropositivity were: presence of farm dogs for more than 5 years (OR: 1.9), access to farm by wild carnivores (OR: 3.1) and compromised farm hygienic status (OR: 3.4). Abortion, retention of foetal membrane and metritis were the most frequently reported clinical reproductive disorders among seropositive cattle. Together, these finding indicate that N. caninum infection is highly prevalent, widely distributed and clinically important in dairy and breeding cattle of Ethiopia. N. caninum should be considered an important infectious cause of reproductive disorders in Ethiopian cattle, and the risk factors for exposure identified here should be used as basis for implementing control measures that could limit the transmission of this infection.

The status of bovine brucellosis in Ethiopia with special emphasis on exotic and cross bred cattle in dairy and breeding farms.

A cross-sectional study was conducted to investigate the seroprevalence of brucellosis and identify risk factors in exotic and cross bred cattle in Ethiopia. A total of 2334 cattle from 273 farms were tested serially for Brucella antibodies using the Rose Bengal Plate Test (RBPT) and the Compliment Fixation Test (CFT). The overall animal level seroprevalence was 1.9% (95% CI: 1.2, 2.6), with urban and peri-urban dairy 2.4% (95% CI: 1.4, 3.4), commercial 1.5% (95% CI: 0.5, 2.5) and breeding farms 1.5% (95% CI: 0.2, 3.2). The overall farm level prevalence was 10.6% (95% CI: 6.9, 14.3), with 8.6% (95% CI: 4.8, 12.4) in urban and peri-urban dairy followed by 16.9% (95% CI: 7.3, 26.6) in commercial and 20.0% (95% CI: 0.0, 59.4) in breeding farms. At individual animal level, purchased cows and adult age groups were observed to associate with Brucella seropositivity while presence of small ruminants on the farm was the only factor associated with increased risk of herd level Brucella infection. The lack of association between reproductive disorders and Brucella seroprevalence suggest that other causes largely outweigh as causes of the aforesaid disorder in studied production systems and demands an investigation. Finally, the need for isolation and characterization of circulating Brucella spp. and institution of regulatory measures to reinforce farm biosecurity was suggested.

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.