Zoonoses are diseases transmitted from animals to humans, posing a great threat to the health and life of people all over the world. According to WHO estimations, 600 million cases of diseases caused by contaminated food were noted in 2010, including almost 350 million caused by pathogenic bacteria. Campylobacter, Salmonella, as well as Yersinia enterocolitica and Listeria monocytogenes may dwell in livestock (poultry, cattle, and swine) but are also found in wild animals, pets, fish, and rodents. Animals, often being asymptomatic carriers of pathogens, excrete them with faeces, thus delivering them to the environment. Therefore, pathogens may invade new individuals, as well as reside on vegetables and fruits. Pathogenic bacteria also penetrate food production areas and may remain there in the form of a biofilm covering the surfaces of machines and equipment. A common occurrence of microbes in food products, as well as their improper or careless processing, leads to common poisonings. Symptoms of foodborne infections may be mild, sometimes flu-like, but they also may be accompanied by severe complications, some even fatal. The aim of the paper is to summarize and provide information on campylobacteriosis, salmonellosis, yersiniosis, and listeriosis and the aetiological factors of those diseases, along with the general characteristics of pathogens, virulence factors, and reservoirs.

https://www.mdpi.com/1660-4601/15/5/863/pdf

Campylobacteriosis, Salmonellosis, Yersiniosis, and Listeriosis as Zoonotic Foodborne Diseases: A Review

Background Human echinococcosis is a neglected zoonosis caused by parasites of the genus Echinococcus. The most frequent clinical forms of echinococcosis, cystic echinococcosis (CE) and alveolar echinococcosis (AE), are responsible for a substantial health and economic burden, particularly to low-income societies. Quantitative epidemiology can provide important information to improve the understanding of parasite transmission and hence is an important part of efforts to control this disease. The purpose of this review is to give an insight on factors associated with echinococcosis in animal hosts by summarising significant results reported from epidemiological studies identified through a systematic search. Methodology and principal findings The systematic search was conducted mainly in electronic databases but a few additional records were obtained from other sources. Retrieved entries were examined in order to identify available peer-reviewed epidemiological studies that found significant risk factors for infection using associative statistical methods. One hundred studies met the eligibility criteria and were suitable for data extraction. Epidemiological factors associated with increased risk of E. granulosus infection in dogs included feeding with raw viscera, possibility of scavenging dead animals, lack of anthelmintic treatment and owners' poor health education and indicators of poverty. Key factors associated with E. granulosus infection in intermediate hosts were related to the hosts' age and the intensity of environmental contamination with parasite eggs. E. multilocularis transmission dynamics in animal hosts depended on the interaction of several ecological factors, such as hosts' population densities, host-prey interactions, landscape characteristics, climate conditions and human-related activities. Conclusions/significance Results derived from epidemiological studies provide a better understanding of the behavioural, biological and ecological factors involved in the transmission of this parasite and hence can aid in the design of more effective control strategies.

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A Systematic Review of the Epidemiology of Echinococcosis in Domestic and Wild Animals

This thesis is based on seven related studies on Ethiopian indigenous Horro and Menz sheep breeds and crossbreds of Menz with exotic breeds to test the general hypothesis that there exist genetic and environmental dependent variations among and within breeds that could be utilised to improve overall productivity and health of the Ethiopian sheep population. The specific studies deal with growth, survival, causes of mortality, risk factors for major causes of mortality, outbreak investigations, maedi-visna, and economics of anthelmintic treatment and supplementation. Results of studies on lamb growth and survival revealed that Horro lambs were heavier than Menz lambs both at birth and weaning. Birth weight increased significantly from the first to third parity; was higher for lambs born as singles than multiples, and for male than female lambs. Lambs born in the wet season had higher birth weight, pre-weaning average daily weight gain and weaning weight than their contemporaries born in the dry season. Pre- and post-weaning mortalities were 33.1% and 54.5% for the Horro and 19.2% and 25.9% for the Menz sheep. Cumulative mortality up to yearling was more than twice as high for Horro than for Menz lambs (69.6 vs. 30.2%). Mortality was higher for lambs born in the dry season compared to those born in the wet season, for multiple-born lambs than singles, and for male lambs than females. There was a positive relationship within breed between birth weight and survival at all ages. Causes of mortality were similar in Horro and Menz, pneumonia accounting for more than half of all deaths, followed by digestive and gastrointestinal problems, endoparasitism, starvation-mismothering-exposure complex and septicaemia. Within breed, sires were a significant source of variation for lamb growth and survival. A retrospective case-control study conducted on 6718 sheep of the Horro and Menz breeds on risk factors for mortality associated with respiratory diseases revealed that 54.4% of total mortality was due to respiratory diseases. Annual mortality associated with respiratory diseases ranged from 6.3 to 19.0%, and breed, sex and month of the year were significant sources of variation. Mortality associated with respiratory diseases was higher for the Horro than for the Menz breed (16.5% vs. 12.4%), and between October and March than between April and September. There was a significant relationship between monthly mortality associated with respiratory diseases and monthly average minimum air temperatures and with the average monthly daily deviation between maximum and minimum air temperatures. Estimation of genetic and environmental parameters for growth traits showed that the maternal genetic component was important for birth weight, weaning weight and pre-weaning average daily gain. The contribution of the permanent environmental component in the models was also substantial but less important than the common (litter) environmental component. Total heritability estimates for Menz and Horro were generally low to moderate at 0.22 vs. 0.26 for birth weight, 0.15 vs. 0.12 for weaning weight, 0.21 vs. 0.04 for yearling weight, 0.14 vs. 0.11 for pre-weaning average daily gain, and 0.11 vs. 0.11 for post-weaning average daily gain. Estimates of genetic parameters on lamb survival from the mixed Linear Model and Survival Analysis were compared. For the mixed Linear Model, survival defined as a binary trait measured at different pre-determined time, and for the Survival Analysis, survival defined as time to respective periods for lamb surviving (censored records) and time to death (uncensored records) was used. The maternal genetic effect was important for lamb survival at all survival periods. The heritabilities from Survival Analysis (0.3% to 18.5%) were higher than those obtained with the mixed Linear Model (0.5% to 5.6%). The accuracies of predicted breeding values were also higher for the traits analysed with Survival Analysis. Some limitations of Survival Analysis are discussed. An investigation into a respiratory diseases outbreak in Menz and Awassi × Menz crossbred sheep revealed that multi-factorial causes were involved. These include peste des petits ruminants (72.3%, serologically confirmed), lungworms, maedi-visna, bacterial bronchopneumonia, enzootic pneumonia and fungal infections. A follow-up serological study revealed that 74% were positive for maedi-visna antibodies in sheep of two ranches, but antibodies for maedi-visna were not detected in sheep and goats from elsewhere in Ethiopia. The maedi-visna was detected in the indigenous Menz and imported pure Awassi and crossbreds of Menz with Awassi, Hampshire, and Corriedale with a significant breed difference in prevalence. This result suggested that the maedi-visna might have been introduced into Ethiopia through sheep importations. The profitability of anthelmintic treatment and supplementation was evaluated in a 2×2×3 factorial experiment under natural sub-clinical helminthosis challenge using partial budget analysis. Supplemented sheep had significantly higher marginal profit per sheep than non-supplemented sheep. Likewise, the anthelmintic treated sheep performed significantly better than their non-treated contemporaries. The indigenous Menz and 50% Awassi × Menz were significantly more profitable during the experimental period than the 75% Awassi × Menz crosses, but ranking of genotypes changed with age. Timely health and management interventions on identified key factors and utilising genetic variation through selection would improve lamb survival and growth. Life-time assessment of economic returns helps to draw early decisions in sheep improvement programmes. Sheep breeding objectives are discussed in the context of reducing risks of genetic loss in low-input systems and improving productivity of indigenous breeds. Breeding programmes are proposed to be based on open-nucleus flocks utilizing government ranches at the top of a three tier system of flocks. Such schemes could be used for conservation and improvement of indigenous breeds as well as for crossbreeding.

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Productivity and health of indigenous sheep breeds and crossbreds in the Central Ethiopian Highlands

Essentials of Veterinary Bacteriology and Mycology

This study assessed knowledge gaps and suggested research priorities in the field of Staphylococcus aureus mastitis. Staphylococcus aureus infecting the mammary gland remains a major problem to the dairy industry worldwide because of its pathogenicity, contagiousness, persistence in the cow environment, colonization of skin or mucosal epithelia, and the poor curing efficacy of treatments. Staphylococcus aureus also constitutes a threat to public health due to food safety and antibiotic usage issues and the potential for bidirectional transmission of strains between humans and dairy animals (cows and small ruminants). Gaps have been identified in (i) understanding the molecular basis for pathogenesis of S. aureus mastitis, (ii) identifying staphylococcal antigens inducing protection and (iii) determining the cell-mediated immune responses to infection and vaccination. The recommended priorities for research are (i) improved diagnostic methods for early detection of infection and intervention through treatment or management, (ii) development of experimental models to investigate the strategies used by S. aureus to survive within the mammary gland and resist treatment with anti-microbials, (iii) investigation of the basis for cow-to-cow variation in response to S. aureus mastitis, (iv) identification of the immune responses (adaptive and innate) induced by infection or vaccination and (v) antibacterial discovery programmes to develop new, more effective, narrow spectrum antibacterial agents for the treatment of S. aureus mastitis. With the availability and ongoing improvement of molecular research tools, these objectives may not be out of reach in the future.

Knowledge gaps and research priorities in Staphylococcus aureus mastitis control.

A cross-sectional study was carried out from October 2008 to May 2009 in smallholder dairy farms in and around Hawassa to estimate the prevalence of mastitis, to isolate and characterize major bacterial pathogens, and to identify possible associated factors. The study involved a total of 201 milking cows randomly drawn from smallholder farms. The prevalence of clinical and subclinical mastitis was determined through clinical examination of the udder and using mastitis indicator paper (Bovivet® indicator paper, Kruuse, Denmark). The prevalence of mastitis at cow and quarter level was 30.3 (61/201) and 10.3 (79/766), respectively. Subclinical mastitis was 25.4% and 5.0% was clinical. Stage of lactation significantly affected (P 0.05) on the prevalence of mastitis. The pathogens isolated from mastitic cows were Staphylococcus aureus (48.6%), other staphylococci species (15.7%), Streptococcus agalactiae (11.4%), other streptococci (17.1%), Bacillus species (2.9%), and coliforms (Escherichia coli and Klebsiella species) (4.3%). Strict hygienic measure of housing and bedding should be considered, in reducing the prevalence of mastitis.

Major causes of mastitis and associated risk factors in smallholder dairy farms in and around Hawassa, Southern Ethiopia

A survey aimed at determining the status of ticks in cattle, sheep and goats in Bedelle district (Southwestern Ethiopia) was carried out from November 2007 to April 2008. Out of the total 330 animals examined, 314 (95.2%) were found to be infested (harbouring of at least a single tick). High rates of infestations were recorded across all three host species. Factors like month of collection, age and sex of host species did not show significant association with infestation rates. A total of 5,507 ticks belonging to three genera (i.e. Amblyomma, Boophilus and Rhipicephalus) were collected during the study period of which six species were identified. The species of ticks encountered comprise of Amblyomma cohaerens (44.1%), Amblyomma variegatum (13.8%), Amblyomma lepidum (1.2%), Boophilus decoloratus (24.9%), Rhipicephalus evertsi evertsi (14.3%) and Rhipicephalus lunulatus (1.7%). As about 86.7% (4,772) of the ticks were collected from cattle, it was recognised that this could be an evidence of host preference where cattle are serving as principal host while sheep and goats serve as alternative hosts. The role of ecological factors and little attention paid by livestock owners for treatment of animals against ticks are suggested to result in the abundance of ticks. Acaricide spraying should be strategically applied to control ticks. Better result could be achieved if an emphasis is being put on spraying cattle. Studies on tick-borne diseases, involvement of wildlife species as well as related factors are recommended as they may provide a valuable basis for designing and launching an all-round control programme in the country.

Survey of ixodid ticks in domestic ruminants in Bedelle district, Southwestern Ethiopia.

A cross-sectional study to estimate the prevalence of fasciolosis in slaughtered cattle was conducted between November 2010 and April 2011 in Addis Ababa abattoir, Ethiopia. A total of 600 livers from cattle selected with systematic random sampling were examined for presence and burden of liver fluke. Of 600 examined cattle, 122 (20.3%) were infected with Fasciola. Both species of Fasciola were identified during the study. Fasciola hepatica was recovered from the livers of 91 (15.2%) cattle while F. gigantica was collected from 19 (3.2%) livers. Mixed infection with both species was observed in 7 (1.2 %) animals and 19 (3.2%) cattle were infected with unidentified immature liver flukes. Worm count on the 122 infected livers revealed a mean fluke count of 73.5 per liver, with maximum and minimum fluke count of 152 and 2 respectively. Fasciola infection was highly associated (P <0.001) with body condition. Animals with lean body condition were 6.9 (95%CI=3.60 - 13.15) times more likely to be infected as compared to fat cattle. It is concluded that fasciolosis, due to F. hepatica and F. gigantica, is prevalent in cattle in Ethiopia. Fasciolosis is an economically important disease Study Area and Animals: The study was conducted on of domestic livestock, in particular cattle and sheep. 600 adult cattle slaughtered in Addis Ababa abattoir The disease is caused by digenean trematodes of between November 2010 and April 2011. Addis Ababa is the genus Fasciola, commonly referred to as liver flukes. the capital city of Ethiopia located in the central highlands The two species most commonly implicated as the of the country at an altitude of 2500 m.a.s.l. The cattle etiological agents of fasciolosis are F. hepatica and slaughtered in the abattoir were collected from different F. gigantica. F. hepatica has a worldwide distribution parts of the country which is characterized by widely but predominates in temperate zones while F. gigantica varying climato-ecological conditions mainly due to is found on most continents, primarily in tropical altitudinal differences. It is often difficult to trace the regions (1). origin of the animals as they usually pass a chain of Several abattoir surveys conducted in various markets. Some animals come directly to the abattoir from parts of Ethiopia have demonstrated the presence of grazing while others pass through feedlots where they are fasciolosis, due to F. hepatica and F. gigantica, in routinely de-wormed and fed straw/hay based ruminants. Some studies tried to demonstrate the concentrate. All cattle included in the study, except economic losses associated with liver condemnation (2-5). seven, were male and the majority, except only 16, was Because epidemiology of fasciolosis is dynamic and local indigenous cattle. may change with years (6), it is important to monitor its development to determine trends in prevalence. Study Design and Sampling Procedure: The study was The present study was, therefore, aimed at estimating the cross-sectional study whereby the study animals were prevalence of fasciolosis in cattle brought from different selected from the slaughter line using systematic random parts of the country and slaughtered in Addis Ababa sampling in such a way that 10 animals are examined a day abattoir. from a group of varying number of cattle slaughtered in

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Fasciolosis in Slaughtered Cattle in Addis Ababa Abattoir, Ethiopia

A bacteriological study of Salmonella Gallinarum/Pullorum was conducted in intensively managed chickens in Hawassa, Ethiopia between November 2008 and May 2009. The objectives of the study were to estimate the bacteriological prevalence of S. Gallinarum/Pullorum in apparently healthy chickens and to assess the proportional morbidity/mortality from S. Gallinarum/Pullorum in sick/dead chickens. Cloacal swabs were collected from a total of 380 randomly selected chickens from 3 poultry farms to estimate the prevalence, whereas necropsy samples of liver, spleen and ceca were collected from 31 sick/dead chickens to estimate the proportional morbidity/mortality. The prevalence of Salmonella infection (S. Gallinaum/Pullorum) was 0.8% (3/380), while isolation was possible from 16.1% (5/31) sick/dead chickens. Only S. Gallinarum was isolated from cloacal swabs. Of the 6 isolates obtained from necropsy samples 1 was S. Pullorum and the rest 5 S. Gallinarum; and, 3 were from liver, 2 from cecum and 1 from spleen. It is concluded that salmonellosis is prevalent and fowl typhoid and pullorum disease have significant role in morbidity and mortality of intensively managed chickens in Hawassa. This result may indicate the challenge that the poultry industry of the country may face from S. Gallinarum/Pullorum in the future in its intensification. Concerted efforts, therefore, should be made at national and local levels to control the diseases. Keywords ∙ Ethiopia ∙ Hawassa ∙ Isolation ∙ Prevalence ∙ Salmonella Gallinarum-
Pullorum

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Prevalence of Salmonella infection in intensive poultry farms in Hawassa and isolation of Salmonella species from sick and dead chickens.

This work was conducted to estimate the seroprevalence, to identify potential factors that influence seroprevalence of bovine viral diarrhea virus (BVDV), and to investigate the association between BVDV serostatus and occurrence of reproductive disorders in dairy cattle in three milksheds in Ethiopia. A total of 1379 serum samples were obtained from cattle randomly selected from 149 herds from three milksheds representing central, southern, and western Ethiopia. Sera samples were examined for bovine viral diarrhea virus (BVDV) antibodies using commercial competitive enzyme-linked immunosorbent assay (ELISA) kit. Logistic regression analysis was employed to investigate associations between risk factors and the risk of BVDV seroprevalence, and BVDV serostatus and reproductive disorders. Seroreaction to BVDV antigens was detected in 32.6% of the 1379 cattle and 69.8% of the 149 herds sampled. Factors associated with BVDV seroplevalence were age, breed, and herd size (P   0.05). Risk of reproductive disorders was not affected by BVDV serostatus, except for repeat breeding (P > 0.05). The present study demonstrated that BVDV has wide distribution in the country being detected in all the 15 conurbations and 69.8% of herds involved in the study.

Kassaye Aragaw

Papers

Major causes of mastitis and associated risk factors in smallholder dairy farms in and around Hawassa, Southern Ethiopia

Survey of ixodid ticks in domestic ruminants in Bedelle district, Southwestern Ethiopia.

Fasciolosis in Slaughtered Cattle in Addis Ababa Abattoir, Ethiopia

Prevalence of Salmonella infection in intensive poultry farms in Hawassa and isolation of Salmonella species from sick and dead chickens.

Seroprevalence and factors associated with bovine viral diarrhea virus (BVDV) infection in dairy cattle in three milksheds in Ethiopia.