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.

Detection of sheep-associated malignant catarrhal fever from clinical cases in Ethiopian cattle.

Mucoid nasal discharge, loss of weight, decreased milk production, diarrhoea, salivation, dyspnoea, fever, lacrimation, bilateral corneal opacity and bloody urine were observed in cattle located in the Arbe Gona district of southern Ethiopia. The disease was associated with a high case fatality rate: diseased cattle died within four to five days after showing clinical signs. The clinical presentation, gross pathological observations, histopathological findings and epidemiological data strongly suggested malignant catarrhal fever. Subsequently, the ovine herpesvirus type 2 (OvHV-2) DNA polymerase (UL30) gene was detected in pathological tissue samples using pan-herpesvirus nested polymerase chain reaction (PCR) and real-time PCR. As far as the authors are aware, this is the first report of a diagnostic investigation resulting in the detection of ovine OvHV-2 in cattle and confirming the existence of sheep-associated malignant catarrhal fever in Ethiopia.

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.

Contagious caprine pleuropneumonia and Mannheimia haemolytica-associated acute respiratory disease of goats and sheep in Afar Region, Ethiopia.

In April 2002, an investigation into an outbreak of acute respiratory disease in goats and sheep in Milae (Afar), Ethiopia was conducted. The investigation involved 4 flocks (722 sheep and 750 goats in total) and comprised the disease history, clinical and post-mortem examination, and microbiological analysis of nasal swabs, lung lesions, and pleural fluid samples. Clinically diseased animals exhibited severe respiratory distress, and necropsy of two of the goats demonstrated fibrinous pneumonia, lung sequestra, and excessive accumulation of straw coloured fluid in the thoracic cavity. Mannheimia haemolytica biotype T was isolated from nine (six goats and three sheep) out of 23 nasal swabs (39.1%). In the two necropsied animals Mycoplasma capricolum subsp. capripneumoniae (Mccp) was isolated from the lungs, and Mannheimia haemolytica biotype T was isolated from lung lesions and thoracic fluid. An unidentified Mycoplasma species was isolated from the thoracic fluid of one of the goats. Pseudomonas aeruginosa was isolated from a lung sequestrum of one of the necropsied goats. In vitro antimicrobial susceptibility test results indicated that two (33.3%) of the six M. haemolytica isolates that were tested were resistant to ampicillin and penicillin G, three (50%) to tetracycline, four (66.7%) to oxacillin, five (83.3%) to erythromycin, and six (100%) to clindamycin. Pseudomonas aeruginosa was resistant to all of the different classes of antimicrobials that were tested. Pleuropneumonia caused by Mccp, and secondary complications caused by M. haemolytica and the other unidentified Mycoplasma species, were confirmed as the cause of the outbreak. Morbidity was not associated with the species of animals affected (P > 0.05); however, mortality was significantly higher in goats than sheep (P < 0.05).

Emergence of Lineage IV Peste des Petits Ruminants Virus in Ethiopia: Complete Genome Sequence of an Ethiopian Isolate 2010.

Isolates of peste des petits ruminants virus (PPRV) can be segregated genetically into four lineages. For decades, lineages I-III have been reported across Africa whilst lineage IV has predominantly circulated across Asia. However, the lineage distribution is currently changing in Africa. Importantly, full genome sequence data for African field isolates have been lacking. Here, we announce the first complete genome sequence of a field isolate of peste des petits ruminants virus (PPRV) from East Africa. This isolate was derived from the intestine of a goat suffering from severe clinical disease during the 2010 outbreak in Ethiopia. The full genome sequence of this isolate, PPRV Ethiopia/2010, clusters genetically with other lineage IV isolates of PPRV, sharing high levels of sequence identity across the genome. Further, we have carried out a phylogenetic analysis of all of the available African partial N gene and F gene PPRV sequences to investigate the epidemiology of PPRV with a focus on the emergence of different lineages of PPRV in Africa.

African horse sickness outbreaks caused by multiple virus types in Ethiopia.

African horse sickness (AHS) is associated with high morbidity and mortality in equids, especially horses. A retrospective analysis was carried out concerning 737 AHS outbreaks that occurred during 2007-2010 in Ethiopia. A total of ten outbreaks were investigated in the study period. All four forms of the disease (pulmonary, cardiac, horse sickness fever and the combined form) were observed, with the cardiac form being the most prevalent. Multiple African horse sickness virus serotypes (AHSV-2, AHSV-4, AHSV-6, AHSV-8 and AHSV-9) were detected by molecular methods (type-specific real-time RT-PCR assays), and fourteen isolates were derived from blood and tissue samples collected during 2009-2010. This is the first report of AHSV-4, AHSV-6 or AHSV-8 in Ethiopia.

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.

Epidemiological study on foot-and-mouth disease in cattle: seroprevalence and risk factor assessment in South Omo zone, south-western Ethiopia.

A cross-sectional sero-epidemiological study was conducted in seven districts of the South Omo zone, south-western Ethiopia, between October 2008 and May 2009 with the objective of determining the seroprevalence of foot-and-mouth disease (FMD) in cattle and identifying the potential risk factors associated with the disease. In total, 770 cattle sera samples were collected and submitted to the National Veterinary Institute (NVI), Debre Zeit, Ethiopia, for screening using the 3ABC-ELISA. The overall seroprevalence of 8.18% (n=63) was recorded in the study. The highest district-level prevalence was observed in Bennatsemay district (30.2%), and the lowest prevalence was in Malle and Debub Aari districts, each with prevalence of 6.3%. The difference in seropositivity of FMD in the studied districts was found to be statistically significant. From the various risk factors analysed, age of animal, contact history with wild animals, distance of the herd from parks and wild animals' sanctuary and movement pattern of herds in search of pasture and water from area to area were found to be significantly associated (P<0.05) with the seroprevalence of FMD. The results of this study showed that FMD is an important cattle disease in the study areas. Thus, an appropriate control strategy has to be designed and applied, which could involve regulation of transboundary cattle movement, prevention of contact with wildlife and vaccination against the circulating virus strain.

Evaluation of the xerovac process for the preparation of heat tolerant contagious bovine pleuropneumonia (CBPP) vaccine.

The study was conducted with the aim of evaluating the xerovac process as a method for preparing contagious bovine pleuropneumonia (CBPP) vaccine with increased heat resistance. The thermo-protective effects of various concentrations of trehalose in mycoplasma growth medium, various concentrations of trehalose in the dehydration stabilizer and the importance of some divalent cations were assessed. The results obtained indicate that a rapid dehydration of CBPP vaccine following the xerovac method and in an excipient composed of a high concentration of trehalose, renders the product more heat tolerant than a similar vaccine prepared using a regular or an extended freeze drying regime. It was also demonstrated that the addition of chitosan as a mycoplasma precipitating agent conferred additional heat resistance to the vaccine. It is suggested that the application of the xerovac process in the dehydration of CBPP vaccine offers the advantages of a faster, cheaper and easier process over the conventional dehydration methods like freeze drying.

Xerovac: an ultra rapid method for the dehydration and preservation of live attenuated Rinderpest and Peste des Petits ruminants vaccines.

The accepted procedure for the long-term preservation of live viruses and bacteria in vaccines has been lyophilisation. We show that thermolabile viruses can be dehydrated in vitro, within 18 h, in an excipient containing trehalose. We further demonstrate that in the resulting dehydrated state, where the viruses are captive in a metastable glass composed of trehalose, they are capable of resisting 45 degrees C for a period of 14 days with minimal loss of potency. The degree of thermotolerance achieved matches that of current 'thermostable' lyophilised vaccines, but with the distinct advantage of a shorter, cheaper and simpler process. The development and utilisation of this process can make significant improvements in current live virus vaccine production. It presents a further step away from dependence on mandatory low temperature refrigerated storage and could lead to greater confidence in vaccine stability, potency and efficacy.