Molecular detection and phylogenetic analysis of Peste des petits ruminants virus circulating in small ruminants in eastern Amhara region, Ethiopia.

BACKGROUND: Peste des Petits Ruminants (PPR) is a severe, highly infectious and fatal viral disease of small ruminants. Four lineages of PPR virus have been identified globally based on sequence analysis of the nucleoprotein (N) and fusion (F) gene. The aim of this study was to isolate and genetically characterize recently circulating PPR virus in small ruminants in the eastern Amhara region in Ethiopia. A total of 28 anti-mortem samples (gum debris, nasal and ocular swab) were collected from clinically suspicious animals and examined for the presence of PPRV by a one-step RT-PCR assay. Samples positive with RT-PCR were subjected to isolation of the virus which were subsequently genetically characterized by sequencing of the nucleoprotein (N) gene and phylogenetic analysis of PPR virus (PPRV) strains. RESULTS: Of the 28 clinical samples examined, 46.4% were positive with RT-PCR for viral nucleic acid. The PPRV was successfully isolated on CHS-20 cell line with the ovine signaling lymphocyte activation molecule (SLAM) receptor expressed on the cell surface and confirmed with RT-PCR and IFAT assay. The nucleotide sequence and phylogenetic analysis indicated that the PPRV obtained were clustered genetically with Lineage IV isolates of the virus. CONCLUSION: The successful isolation of the virus and molecular findings of this study confirmed active lineage IV PPRV infections among populations of sheep and goats in eastern Amhara, suggesting risks for potential spread of the disease to currently free areas. Thus, we recommend systematic vaccination to contain outbreaks in affected districts and geographically linked surrounding districts to which the disease could potentially spread due to different epidemiological linkages.

Sero-prevalence of lumpy skin disease in selected districts of West Wollega zone, Ethiopia.

BACKGROUND: Lumpy skin disease (LSD) is an economically devastating emerging viral disease of cattle caused by a virus associated with the Neethlig poxvirus in the genus Capripoxvirus of the family Poxviridae. A cross-sectional study was conducted from October, 2012 to May, 2013 in two districts of Western Wollega of Oromiya Regional State, with the objectives to determine animal and herd level seroprevalence of lumpy skin disease in the study area. The study population comprised of indigenous and crossbred cattle. Multi-stage sampling method was applied to select cattle and herd owners for the interviews. A total of 544 sera samples were collected from 252 herds and the serological test were conducted using indirect fluorescent antibody test (IFAT). RESULT: An overall individual level sero-prevalence of 6.43% (n = 35) and herd level seroprevalence of 5.95% (n = 15) were estimated. There was significant variation (P < 0.05) between the seroprevalence in Gimbi (4.41%) and Lalo Assabi (8.46%) districts at animal level. The sero-prevalence of LSD exposure among breeds (local and cross) was significantly different in that it was found significantly higher in cross breeds (OR = 2.85, p = 0.016) than in local zebu. There was statistically significant difference (p = 0.384) among the age groups (adult, young and calf) in the sero-prevalence of LSD. The average sero-prevalence according to age groups was 8.78%, 5% and 2.74% in adults, youngs and calves, respectively and this shows the prevalence was very low in calves. The current finding revealed no significant variation between male and female animals (p > 0.05). In addition, there was no significant association between seropositivity to LSD and, the agro-climatic zones (midland and highland). CONCLUSION: The present study revealed a moderate distribution of sero-positive cattle in the study area and the disease observed warrants future detailed study on the spread of the disease in the area.

Spoligotype analysis of Mycobacterium bovis isolates from cattle and assessment of zoonotic TB transmission among individuals working in bovine TB-infected dairy farms in Ethiopia.

Bovine tuberculosis (bTB) is a disease with impact on dairy productivity, as well as having the potential for zoonotic transmission. Understanding the genetic diversity of the disease agent Mycobacterium bovis is important for identifying its routes of transmission. Here we investigated the level of genetic diversity of M. bovis isolates and assessed the zoonotic potential in risk groups of people working in bTB-infected dairy farms in central Ethiopia. M. bovis was isolated and spoligotyped from tissue lesions collected from slaughtered cattle as well as from raw milk collected from bTB positive cows in dairy farms from six urban areas of central Ethiopia. From consented dairy farm workers, knowledge and practices related to zoonotic TB transmission, together with demographic and clinical information, was collected through interviews. Sputum or Fine Needle Aspirate (FNA) samples were collected from suspected TB cases. Spoligotyping of 55 M. bovis isolates that originated either from cattle tissues with tuberculous lesion or from raw milk revealed seven spoligotype patterns where SB1176 was the most prevalent type (47.3%). Most isolates (89.1%) were of the M. bovis African 2 clonal complex. All sputum and FNA samples from 41 dairy farm workers with symptoms of TB were culture negative for any mycobacteria. Among the 41 TB suspected farm workers, 61% did not know about bTB in cattle and its zoonotic potential, and over two-third of these workers practiced raw milk consumption. Our spoligotype analysis suggests a wider transmission of a single spoligotype in the study area. The results reported here may be useful in guiding future work to identify the source and direction of bTB transmission and hence design of a control strategy. Isolation of M. bovis from milk, knowledge gap on zoonotic TB and practice of consumption of raw milk in the study population showed potential risk for zoonotic transmission.

Camel production systems in Ethiopia: a review of literature with notes on MERS-CoV risk factors.

Camels are the most adapted species to the harsh conditions of arid/semi-arid rangelands of Ethiopia where pastoralism is the dominant mode of life and mobility is an inherent strategy to efficiently utilize the spatially and temporally distributed pasture and water resources. Usually, large numbers of camels and other domestic animals from many different herds/flocks congregate at watering sites, and this may create a perfect condition for disease transmission and spread among animals. The same water sources are also shared by multitudes of wild animals. Camel herd sizes per household range from few heads (five to ten) to several hundreds. Female camels account for more than 75% of the herd. Male camels are usually sold early as pack animals or for slaughter. Female camels may remain fertile up to 25 years, during which time they produce eight to ten calves. Camels are herded during daytime on communal rangelands. During night, they are kept in traditional kraals around homesteads. Breeding time is short and seasonal and is affected by rainfall patterns and feed availability. Usually, only men milk camels. Milking frequency ranges from two to five times per day. Washing of hands, milking vessels, the udder and teats is not practised by many prior to milking the camels. Besides, the milking area is generally full of dust and dung and without shade. This affects the quality and safety of the produced milk. Pathogens and diseases of camelids are less well known; however, they are suspected as zoonotic sources for the human infection with the Middle East respiratory syndrome coronavirus. There is an increasing need to determine whether camels are clinically susceptible, act as potential reservoirs and maintenance or bridge hosts, to viral pathogens.

Seroprevalence and risk factors of lumpy skin disease in Ethiopia.

Lumpy skin disease (LSD) is an acute or inapparent viral disease of cattle which is endemic in many African and Middle East countries. LSD is one of the major transboundary livestock diseases in Ethiopia. A cross-sectional study using multistage cluster sampling was undertaken in central and north-western parts of Ethiopia with the objectives to estimate seroprevalence and to identify and quantify risk factors contributing to the occurrence of the disease. A total of 2386 cattle sera were sampled from 605 herds and 30 clusters (kebeles) located in 10 districts and tested for presence of LSD virus antibodies using virus neutralization test. All the serum samples were collected from cattle having no history of LSD vaccination. The overall animal level and herd level apparent seroprevalences were 25.4% (95% CI: 23.7-27.2) and 48.9% (95% CI: 44.9-52.9), respectively and varied significantly between districts. The true animal level and herd level prevalences were estimated as 26.5% (95% CI: 24.7-28.3) and 52.6% (95% CI: 48.3-56.9), respectively. At animal level, adult age (OR = 2.44 (95% CI: 1.67-3.55) compared to calf), contact with other animals (OR = 0.41 (95% CI: 0.23-0.74), compared to no contact) and presence of water bodies (OR = 1.61 (95% CI: 1.03-2.52), compared to no such bodies) were identified as the most important risk factors in relation to testing LSD positive. The putative risk factors altitude, breed, sex, and presence of animal trade route showed no significant association with LSD sero-status. Generally, cattle population with many adult animals and that live in wet areas are at highest risk, whereas cattle in frequent contact with other animals and animal species have lower risk, potentially due to a dilution effect of vectors.

Serological Investigation of Peste Des Petits Ruminants in East Shewa and Arsi Zones, Oromia Region, Ethiopia.

Peste des petits ruminant (PPR) is an economically important disease of small ruminants with a rapidly expanding geographical distribution. There are fragmented reports to the occurrence and distribution of the disease in Ethiopia. A total of 700 serum samples were collected from goats and sheep to detect the presence of antibody against PPR virus using Competitive Enzyme-Linked Immunosorbent Assay (C-ELISA). An overall PPR seropositivity was reported to be 48.43% in the area. There is no statistically significant difference in the seroprevalence of the disease between sheep and goats (50.85% and 46.68%), respectively. However, there was statistically significant variation (P < 0.05) in the seroprevalence of the disease in young (33.9%) and adult (55.8%) age categories. The seroprevalence in male and female was 42.07% and 50.09%, respectively, where the variation was statistically not significant (P > 0.05). High seroprevalence of Peste des petites ruminants in the study area indicated the virus circulation and endemicity of the disease. The disease causes substantial economic losses by affecting the livelihood of the farmers. Therefore, control measures should be put in place to minimize the loss associated with the disease.

Economic impact of lumpy skin disease and cost effectiveness of vaccination for the control of outbreaks in Ethiopia.

Lumpy skin disease (LSD), an infectious viral disease of cattle, causes considerable financial losses in livestock industry of affected countries. A questionnaire survey with the objectives of determining direct economic losses of LSD (mortality loss, milk loss, draft loss) and treatment costs (medication and labour cost) per affected herd, and assessing the cost effectiveness of vaccination as a means for LSD control was carried out in the central and north-western parts of Ethiopia. From a total of 4430 cattle (in 243 herds) surveyed, 941 animals (in 200 herds) were reported to be infected. The overall morbidity and mortality at animal level were 21.2% and 4.5%, and at herd level these were 82.3% and 24.3%. There was a significant difference in animal level morbidity and mortality between categories of animals. Over 94% of the herd owners ranked LSD as a big or very big problem for cattle production. A large proportion (92.2%) of the herd owners indicated that LSD affects cattle marketing. A median loss of USD 375 (USD 325 in local Zebu and USD 1250 in Holstein-Friesian local Zebu cross cattle) was estimated per dead animal. Median losses per affected lactating cow were USD 141 (USD 63 in local Zebu cows and USD 216 in Holstein-Friesian local Zebu cross cows) and, USD 36 per affected ox. Diagnosis and medication cost per affected animal were estimated at USD 5. The median total economic loss of an LSD outbreak at herd level was USD 1176 (USD 489 in subsistence farm and USD 2735 in commercial farm). At herd level, the largest component of the economic loss was due to mortality (USD 1000) followed by milk loss (USD 120). LSD control costs were the least contributor to herd level losses. The total herd level economic losses in the commercial farm type were significantly higher than in the subsistence farm type. The financial analysis showed a positive net profit of USD 136 (USD 56 for subsistence farm herds and USD 283 for commercial herds) per herd due to LSD vaccine investment. It should be noted that only the noticeable direct costs and treatment costs associated with the disease were considered in the study. Generally, vaccination is economically effective and should be encouraged.

Field study on the use of vaccination to control the occurrence of lumpy skin disease in Ethiopian cattle.

The current study was carried out in central and North-western parts of Ethiopia to assess the efficacy of Kenyan sheep pox virus strain vaccine (KS1 O-180) against natural lumpy skin disease (LSD) infection under field conditions by estimating its effect on the transmission and severity of the disease. For this study, an LSD outbreak was defined as the occurrence of at least one LSD case in a specified geographical area. An observational study was conducted on a total of 2053 (1304 vaccinated and 749 unvaccinated) cattle in 339 infected herds located in 10 sub-kebeles and a questionnaire survey was administered to 224 herd owners. Over 60% of the herd owners reported that the vaccine has a low to very low effect in protecting animals against clinical LSD; almost all of them indicated that the vaccine did not induce any adverse reactions. In the unvaccinated group of animals 31.1% were diagnosed with LSD while this was 22.5% in the vaccinated group (P<0.001). Severity of the disease was significantly reduced in vaccinated compared to unvaccinated animals (OR=0.68, 95% CI: 0.49; 0.96). Unvaccinated infected animals were more likely (predicted fraction=0.89) to develop moderate and severe disease than vaccinated infected animals (predicted fraction=0.84). LSD vaccine efficacy for susceptibility was estimated to be 0.46 (i.e. a susceptibility effect of 0.54) while the infectiousness effect of the vaccine was 1.83. In other words, the vaccine reduces the susceptibility by a factor of two and increases infectiousness by approximately the same amount. LSD transmission occurred in both vaccinated and unvaccinated animals, the estimated reproduction ratio (R) was 1.21 in unvaccinated animals compared to 1.19 in vaccinated ones, and not significantly different. In conclusion, KS1 O-180 vaccination, as applied currently in Ethiopia, has poor efficacy in protecting cattle populations against LSD, neither by direct clinical protection nor by reducing transmission, and this signifies the urgent need to either improve the quality of the vaccine or to develop potent alternative vaccines that will confer good protection against LSD.

Evaluation of the safety, immunogenicity and efficacy of three capripoxvirus vaccine strains against lumpy skin disease virus.

The safety, immunogenicity and efficacy of three commercially available vaccines against lumpy skin disease (LSD) in cattle have been evaluated using a combination of vaccine challenge experiments and the monitoring of immune responses in vaccinated animals in the field. The three vaccines evaluated in the study included two locally produced (Ethiopian) vaccines (lumpy skin disease virus (LSDV) Neethling and Kenyan sheep and goat pox (KSGP) O-180 strain vaccines) and a Gorgan goat pox (GTP) vaccine manufactured by Jordan Bio-Industries Centre (JOVAC). The latter vaccine was evaluated for the first time in cattle against LSDV. The Ethiopian Neethling and KSGPO-180 vaccines failed to provide protection in cattle against LSDV, whereas the Gorgan GTP vaccine protected all the vaccinated calves from clinical signs of LSD. There was no significant difference in protective efficacy detected between two dosage levels (P=0.2, P=0.25, and P=0.1 for KSGP, Neethling and Gorgan vaccines, respectively). Additionally, the Gorgan GTP vaccinated cattle showed stronger levels of cellular immune responses measured using Delayed-Type Hypersensitivity (DTH) reactions at the vaccination site indicating higher levels of immunogenicity produced by the GTPV vaccine in cattle, as opposed to the other two vaccines. This study indicated, for the first time, that the Gorgan GTP vaccine can effectively protect cattle against LSDV and that the Neethling and KSGP O-180 vaccine were not protective. The results emphasise the need for molecular characterization of the Neethling and KSGP O-180 vaccine seed viruses used for vaccine production in Ethiopia. In addition, the potency and efficacy testing process of the Ethiopian LSD Neethling and KSGP O-180 vaccines should be re-evaluated.

Estimated prevalence and risk factors associated with clinical Lumpy skin disease in north-eastern Ethiopia.

Lumpy skin disease (LSD) is one of the major livestock disease problems in most areas of Ethiopia. A questionnaire-based cross-sectional study was conducted from October 2011 to February 2012 in four selected districts of Afar and Tigray regions to estimate the herd-level prevalence of LSD, and to assess its associated risk factors. Herd-owners were selected based on the willingness to provide information to complete the questionnaire. A total of 393 questionnaires were collected. Out of 393 herd-owners, 173 reported having LSD in their herds, giving an estimated herd- and animal-level prevalence of (44%, 95% CI: 37-50%) and (7.4%, 95% CI: 6-8%), respectively. Herd prevalence between regions and among the districts were significantly different (χ(2)=8, P<0.01 and χ(2)=9.9, P<0.01), respectively. The risk factors of LSD occurrence were introduction of a new animal to the herd, herd size, and utilization of communal grazing and watering points. These management characteristics cannot be readily changed in the studied area, hence, disease control should rely on a greater use of effective LSD vaccines.