Smallholder pig production in Uganda is constrained by poor management and high disease burden, with African swine fever (ASF) being one of the most important contributors. However, data to develop appropriate evidence-based disease mitigating interventions along the pig value chain are lacking. This study aimed at determining risk factors associated with the occurrence of outbreaks of ASF in selected districts. A cross-sectional survey of 1195 pig-keeping households in three districts was carried out between April and July 2013. Households were classified into one of three value chain domains (VCDs) based on where the production was located and where most of the products were sold: rural-rural (R-R), rural-urban (R-U) and urban-urban (U-U). Findings revealed that crop farming is the most common primary activity in the R-R and R-U VCDs, while pig keeping was the most common primary activity in the U-U VCDs. Pigs are mostly kept tethered or left to roam in the R-R and R-U VCDs, while in the U-U VCDs, they are mostly confined in corrals. Nearly 20% of the farmers whose farms were hit by an ASF outbreak subsequently sold all their pigs (healthy and sick) to the market in panic. Factors that positively correlated with recent ASF outbreaks were prompt disposal of dead pigs on farms (P < 0.001, OR = 2.3), wild animals present in the village (P < 0.001, OR = 1.7) and farmers sourcing drugs from stockists (P < 0.001, OR = 1.6); while protective factors were the presence of perimeter fences (P = 0.03, OR = 0.5), attendance of farmers at secondary-school level and above (P < 0.001, OR = 0.6), routine cleaning of the pig pens (P < 0.001, OR = 0.6) and pigs being the only livestock kept by farmer (P = 0.01, OR = 0.7). Given the current situation, there is a need to raise awareness among farmers and other value chain actors of biosecurity measures and create incentives for farmers to report ASF cases.
The aim of this study was to characterize serotypes, phenotypic antimicrobial resistance patterns, and plasmid profiles of 55 Salmonella enterica subsp. enterica isolates in different matrices from 77 pork outlets in Kampala, Uganda. Seven different serovars were identified, namely Enteritidis (60%), Offa (10.9%), Gallinarum (7.3%), Arechavaleta (monophasic) (7.3%), Zanzibar (7.3%), Kampala (5.4%), and Saintpaul (1.8%). Most isolates were obtained from raw pork (40.0%), followed by flies (27.3%), raw vegetables (18.2%), water (12.7%), and roasted pork (1.8%). All but one of the isolates (98%) showed resistance to at least one of the 22 antimicrobials tested, with highest levels of resistance expressed to cefazolin (95%), and cefotaxime (93%). Intermediate resistance was found to ciprofloxacin (58%), chloramphenicol (58%), and amoxicillin-clavulanic acid (56%). Most isolates were susceptible to levofloxacin (75%), sulfamethoxazole-trimethoprim (80%), and ofloxacin (96%). Characterization of strains by PCR based replicon typing detected the presence of FIA, FIB, FIC, HI1, HI2, I1-1y, L/M, N, P, W, T, A/C, K, B/O, X, Y, F and FIIA replicons. Six replicon groups (FIA, W, FIC, FIB, P, and Y) were identified in 53 of the 55 (96.4%) isolates with more than one group existing among 42 different isolates. Although the average number of replicon groups per strain was low (2.6), phenotypical resistance rates remained high implying that some strains seemed to encode resistance on the chromosome or undetected plasmids, respectively. Potential drivers in livestock production and human medicine, and sources of antimicrobial resistance need to be identified to protect public health in Uganda.
Previous research on trichinellosis in Africa focused on isolating Trichinella from wildlife while the role of domestic pigs has remained highly under-researched. Pig keeping in Uganda is historically recent, and evidence on zoonotic pig diseases, including infection with Trichinella species, is scarce. A cross-sectional survey on Trichinella seroprevalence in pigs was conducted in three districts in Central and Eastern Uganda from April 2013 to January 2015. Serum from a random sample of 1125 pigs from 22 villages in Eastern and Central Uganda was examined to detect immunoglobulin G (IgG) against any Trichinella spp. using a commercially available ELISA based on excretory-secretory antigen. ELISA positive samples were confirmed using Western Blot based on somatic antigen of Trichinella spiralis as recommended in previous validation studies. Diaphragm pillar muscle samples (at least 5 g each) of 499 pigs from areas with high ELISA positivity were examined using the artificial digestion method. Overall, 78 of all 1125 animals (6.9%, 95% CI: 5.6-8.6%) tested positive for antibodies against Trichinella spp. in the ELISA at significantly higher levels in Kamuli district compared to Masaka and Mukono districts. Thirty-one percent of the ELISA positive samples were confirmed IgG positive by the Western Blot leading to an overall seroprevalence of 2.1% (95% CI: 1.4-3.2%). The large proportion of ELISA positive samples that could not be confirmed using Western blot may be the result of cross-reactivity with other gastrointestinal helminth infections or unknown host-specific immune response mechanisms in local pig breeds in Uganda. Attempts to isolate muscle larvae for species determination using the artificial digestion method were unsuccessful. Due to the large number of muscle samples examined we are confident that even if pigs are infected, the larval burden in pork is too low to pose a major risk to consumers of developing trichinellosis. This was the first large systematic field investigation of Trichinella infection in domestic pigs in Uganda and its results imply that further studies are needed to identify the Trichinella species involved, and to identify potential sources of infection for humans.
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