Epidemiology of enterotoxigenic escherichia coli and salmonella diarrhea in piglets and weaners from northern and eastern Uganda

Abstract

Uganda is an emerging pig producer in Africa and enterotoxigenic Escherichia coli (ETEC), salmonellae and transmissible gastroenteritis virus (TGEV) infections could be of importance, particularly to farmers with low socioeconomic indicators. A cross-sectional study was conducted from 2011 to 2013 to characterize pig production, understand epidemiology of ETEC and salmonellae and determine occurrence of TGEV infection in pigs from Gulu and Soroti districts in northern and eastern Uganda, respectively. Data from pig herds identified by snowballing were collected through questionnaire surveys and analyses of fecal and tissue samples. In a majority of the households (67%, n = 96) adult pigs and weaners were tethered but the piglets left to roam. Diarrhea was a common sign of disease in piglets and weaners in 38% of the households. Diarrhea observed on piglets and weaners was statistically associated with Salmonella infection (p=0.008). At individual and herd level, the total prevalence of Salmonella was 12% and 39%, respectively. The salmonellae were diverse (20 serovars) and highly resistant to the antimicrobials- sulfamethoxazole, trimethoprim and streptomycin commonly used in humans and livestock in Uganda. However, “intensive” method of pig management versus either “tethering and roaming” (p= 0.016, OR = 0.11; 95% CI 0.02, 0.64) or “semi-intensive” method (p= 0.048, OR = 0.12; 95% CI 0.01, 0.96) protected piglets and weaners against Salmonella infection. From post-mortem and other laboratory examinations diarrhea attributed to ETEC infections was reported. Genes for adhesins, F4 and AIDA-I, were detected in E. coli from piglets, with F4 being the more prevalent. The most predominant toxin gene in E. coli from diarrheic piglets was for STb. The ETEC isolates from seven diarrheic piglets and one weaner were non-hemolytic and of the sero-groups O138, O139, O45 or non-identifiable. In addition TGEV sero-positive pigs from Gulu were reported. The farmers in the study area should be sensitized to adopt practices that reduce the magnitude of these infections such as “intensive” piggery and use of adhesin-based vaccines. There is also a need to conduct similar studies in other parts of Uganda and among large scale pig producers.