Epidemiological investigations of Salmonella and Escherichia coli associated morbidity and mortality in layer chickens in Hawassa city, Southern Ethiopia

Background

This study was conducted with the objectives of estimating the morbidity and mortality rates in layer chickens, identifying the risk factors associated with morbidity and mortality, and identifying the major bacterial pathogens affecting small-scale commercial layers in Hawassa. A longitudinal observational study design was employed from November 2019 to March 2020. The chickens on selected farms were checked for morbidity and mortality twice a week. During each visit, clinical examination of sick birds and pathological investigation of dead birds were conducted. Cloaca samples were collected for isolation and identification of Salmonella spp. and E. coli. A Cox proportional hazard model was used to quantify the effects of various risk factors on the morbidity and mortality rates observed.

Results

Of the 8976 chickens followed, 106 developed clinical disease, giving a morbidity of 1.18% (95% CI: 0.97, 1.43). The overall morbidity rate was 2.37 (95% CI: 1.94, 2.87) per 1000 chicken months. A total of 101 of the chickens under study were found dead, yielding a mortality of 1.13% (95% CI: 0.92, 1.37) and a mortality rate of 2.26 (95% CI: 1.84, 2.75). Multivariable Cox regression analysis showed that farm hygiene, the experience of farm manager, housing condition, housing systems, the availability of veterinary services and age of chicken were important risk factors for morbidity and mortality. Out of 58 cloacal samples collected from sick chickens, 7 (12.07%; 95% CI: 4.99, 23.29) yielded positive results for Salmonella spp., while 25 (43.10%; 95% CI: 30.16, 56.77) yielded positive results for E. coli. Out of swabs collected from 8 randomly selected sick chickens after necropsy, 3 (37.5%) were found to be positive for Salmonella spp. Four (50%) of them were positive for E. coli. Swabs were collected and cultured from 15 dead chickens, and of these, 2 (13.33%) and 7 (46.67%) were found to be positive for Salmonella spp. and E. coli, respectively. Farm hygiene, age of chickens, housing conditions and frequency antibiotics use were important risk factors for colibacillosis and salmonellosis.

Conclusions

Although the incidence of chicken morbidity and mortality was relatively low in the present study, important risk factors have been identified in the poultry farms of Hawassa City, southern Ethiopia. Therefore, comprehensive poultry farm management practices are needed to mitigate risk factors for morbidity and mortality as well as colibacillosis and salmonellosis. Identification of the serotypes of Salmonella spp. and E. coli should be carried out.

Epidemiological Investigation of Morbidity and Mortality of Improved Breeds of Chickens in Small Holder Poultry Farms in Selected Districts of Sidama Region, Ethiopia

Background

A longitudinal study was conducted in six intensive and three semi-intensive poultry farms in Shebedino and Dale districts of Sidama Region, Ethiopia from November 2018 to May 2019. The objectives of the study were to estimate incidence rates of mortality and morbidity, identify the risk factors associated with morbidity and mortality and establish differential diagnosis of major diseases affecting poultry in the area. Chickens belonging to two breeds namely Sasso, and Bovans Brown reared in purposively selected small-scale farms was included from two districts. The chickens on the selected farms were monitored for morbidity and mortality every week. Diagnosis of different diseases was made based on the flock history, age of birds, clinical signs, characteristic gross and microscopic lesions, and fecal flotation technique for coccidiosis. Semi-structured questionnaires were also administered to gather information on the risk factors and farming practices.

Results

The incidence rate of morbidity and mortality in the studied farms was 16.14 and 12.69 per 1000 chicken-week at risk, respectively. The minimum and maximum incidence rates of morbidity were 2.02 and 58.43 cases per 1000 chicken-week at risk, respectively. The minimum and maximum incidence rates of mortality were 0.21 and 58.18 deaths per 1000 chicken-week at risk, respectively. Among the risk factors studied feed type, age of chickens, and number of sick chickens on farms were significantly associated (p < 0.05) with the incidence of disease. Age of chickens and number of sick chickens found on the farms were significantly associated (p < 0.05) with the incidence of death using multivariable logistic regression. Newcastle Disease (ND), Infectious Bursal Disease (IBD), Fowl typhoid, and Coccidiosis were the important diseases identified during the follow up period in the study area. Of the overall mortality and morbidity, 90.48% and 42% were respectively attributed to ND. Infectious bursal disease and Coccidia co-infection occurred in 31.55% of chicken in the infected farms.

Conclusions

The present study documented the incidence rate of morbidity and mortality in smallholder poultry farms in selected districts of Sidama Region. The study findings indicated that infectious diseases appear to be a major constraint to improve chicken production in the study areas. Therefore, the veterinary and livestock authorities should take this into account when planning poultry development activities and setting up systems of livestock production and health monitoring.

Isolation, molecular characterization and sero-prevalence study of foot-and-mouth disease virus circulating in central Ethiopia

BACKGROUND

Ethiopian livestock production and productivity is still very low due to widespread of diseases. Among the diseases, foot-and-mouth disease (FMD) is an extremely contagious and acute viral disease that causes significant economic problems in the country. A cross sectional study design was conducted from September 2015 to May 2016 to isolate and characterize FMD virus from outbreak cases; determine the sero-prevalence of antibodies against FMD virus (FMDV), and assess potential risk factors associated with sero-prevalence of the disease in selected areas of central Ethiopia. A multistage sampling technique was employed to select the study animals. Isolated viruses were characterized by antigen ELISA (IZLER, Brescia, Italy) and by genetic analysis of the sequence of the viral protein 1 (VP1). Sero-prevalence was determined using an ELISA for antibodies against non-structural proteins of FMDV based on the 3ABC proteins (ID Screen® FMD NSP Competition, ID-VET, Grabels, France). Risk factors for sero-prevalence of antibodies against FMD virus was investigated using logistic regression analysis.

RESULT

From outbreak investigation, 28.8% (n = 378) cattle showed signs and lesions suggestive of FMD and 34 samples were subjected to virus isolation. Twenty eight of these cultures exhibited cytopathic effect (CPE) and were serotyped as O, A and SAT 2 FMD viruses. One A and two SAT 2 isolates named A-ETH-19-2015, SAT 2-ETH-18-2015 and SAT 2-ETH-20-2015 were further characterized by phylogenetic analysis. The overall sero-prevalence of antibodies against non-structural proteins of FMDV was 24.2% (n = 574). Cattle herds with crossbreed cattle, with older cattle (> 2 years), and kept together with small ruminants had higher sero-prevalences of antibodies against FMDV (p < 0.05).

CONCLUSION

This study showed that FMD was present in the study areas. Among the associated risk factors, breed, age and herd composition were significantly associated with presence of antibodies against FMD virus. Three different serotypes (A, O and SAT 2) were responsible for the outbreaks of the disease. Genetic analysis indicated that the isolated viruses clustered differently from previous outbreaks. Thus, further molecular analyses coupled with protection potential of the existing vaccines against the isolates should be performed.