Cholera is a major public health problem in the African Great Lakes basin. Two hypotheses might explain this observation, namely the lakes are reservoirs of toxigenic Vibrio cholerae O1 and O139 bacteria, or cholera outbreaks are a result of repeated pathogen introduction from the neighboring communities/countries but the lakes facilitate the introductions. A prospective study was conducted in Uganda between February 2015 and January 2016 in which 28 selected surface water sources were tested for the presence of V. cholerae species using cholera rapid test and multiplex polymerase chain reaction. Of 322 water samples tested, 35 (10.8%) were positive for V. cholerae non O1/non O139 and two samples tested positive for non-toxigenic atypical V. cholerae O139. None of the samples tested had toxigenic V. cholerae O1 or O139 that are responsible for cholera epidemics. The Lake Albert region registered the highest number of positive tests for V. cholerae non O1/non O139 at 47% (9/19). The peak period for V. cholerae non O1/non O139 positive tests was in March–July 2015 which coincided with the first rainy season in Uganda. This study showed that the surface water sources, including the African Great Lakes in Uganda, are less likely to be reservoirs for the observed V. cholerae O1 or O139 epidemics, though they are natural habitats for V. cholerae non O1/non O139 and atypical non-toxigenic V. cholerae O139. Further studies by WGS tests of non-toxigenic atypical V. cholerae O139 and physicochemical tests of surface water sources that supports V. cholerae should be done to provide more information. Since V. cholerae non O1/non O139 may cause other human infections, their continued surveillance is needed to understand their potential pathogenicity.

Background: Water is the most abundant resource on earth, however water scarcity affects more than 40% of people worldwide. Access to safe drinking water is a basic human right and is a United Nations Sustainable Development Goal (SDG) 6. Globally, waterborne diseases such as cholera are responsible for over two million deaths annually. Cholera is a major cause of ill-health in Africa and Uganda. This study aimed to determine the physicochemical characteristics of the surface and spring water in cholera endemic communities of Uganda in order to promote access to safe drinking water. Methods: A longitudinal study was carried out between February 2015 and January 2016 in cholera prone communities of Uganda. Surface and spring water used for domestic purposes including drinking from 27 sites (lakes, rivers, irrigation canal, springs and ponds) were tested monthly to determine the vital physicochemical parameters, namely pH, temperature, dissolved oxygen, conductivity and turbidity. Results: Overall, 318 water samples were tested. Twenty-six percent (36/135) of the tested samples had mean test results that were outside the World Health Organization (WHO) recommended drinking water range. All sites (100%, 27/27) had mean water turbidity values greater than the WHO drinking water recommended standards and the temperature of above 17°C. In addition, 27% (3/11) of the lake sites and 2/5 of the ponds had pH and dissolved oxygen respectively outside the WHO recommended range of 6.5-8.5 for pH and less than 5 mg/L for dissolved oxygen. These physicochemical conditions were ideal for survival of Vibrio. cholerae.

Background: Pig production in Uganda is highly constrained by rampant piglet mortalities with diarrhea being a key feature. The present study was conducted to determine possible involvement of Escherichia coli (E. coli) as agents of diarrhea in piglets and elucidate the factors for their spread and virulence, towards development of mitigation strategies in the smallholder pig value chains in Uganda. Methodology: This was a cross-sectional study carried out from January to August 2020 on pre- and post-weaned piglets from households in Kayunga and Mityana districts of Central Uganda, selected by snowballing method to redundancy. Data about herd management and risk factors for colibacillosis were collected from selected farmers in the two districts. A total of 179 faecal samples were collected from randomly selected neonatal and pre-weaning piglets for bacteriological isolation of Escherichia coli. Virulence (enterotoxin and fimbrial) genes from the isolates were detected by multiplex polymerase chain reaction (PCR) assay. Results: From the 179 faecal samples, a total of 158 (88.3%) E. coli isolates were obtained. Virulence gene markers were detected in 18.4% (29/158) of the isolates. Among the investigated genes encoding for enterotoxin production, STb was the most prevalent (16/158, 10.13%), followed by STa (12/158, 7.59%), while gene for LT was not detected. The gene coding for F4 adhesin was the only one detected while F18 adhesin was not detected from the isolates. On multiple logistic regression analysis, only tertiary educational level (OR=0.141; 95% CI=0.30-0.666; p=0.013) and infrequent use of antibiotics (OR=0.231, 95% CI=0.062-0.859; p=0.029) among the farmers, were the two factors significantly protective of the piglets from diarrhoea. Conclusion: This study reports a high prevalence of enterotoxin gene markers among E. coli isolates in piglets and revealed the potential role of these bacteria in the aetiology of piglet diarrhoea and mortalities in Uganda. Additionally, this study identified risk factors that can be useful in formulating treatment and control strategies of infection caused by these bacteria. Further studies are needed to identify more adhesins these E. coli isolates employ for intestinal colonization, a step that will help inform vaccine development.   French title: Le rôle d'Escherichia coli dans l'étiologie de la diarrhée des porcelets dans certains districts producteurs de porcs du centre de l'Ouganda   Contexte: La production porcine en Ouganda est fortement limitée par la mortalité généralisée des porcelets, la diarrhée étant une caractéristique clé. La présente étude a été menée pour déterminer l'implication possible Escherichia coli piglet diarrhea in Uganda  d'Escherichia coli (E. coli) en tant qu'agents de diarrhée chez les porcelets et élucider les facteurs de leur propagation et de leur virulence, vers le développement de stratégies d'atténuation dans les chaînes de valeur des petits producteurs de porcs en Ouganda. Méthodologie: Il s'agit d'une étude transversale réalisée de janvier à août 2020 sur des porcelets pré- et post-sevrés issus de ménages des districts de Kayunga et Mityana du centre de l'Ouganda, sélectionnés par la méthode boule de neige jusqu'à la redondance. Les données sur la gestion du troupeau et les facteurs de risque de colibacillose ont été recueillies auprès d'éleveurs sélectionnés dans les deux districts. Au total, 179 échantillons de matières fécales ont été prélevés sur des porcelets néonatals et en pré-sevrage sélectionnés au hasard pour l'isolement bactériologique d'Escherichia coli. Les gènes de virulence (entérotoxine et fimbrial) des isolats ont été détectés par une amplification en chaîne par polymérase (PCR) multiplex. Résultats: À partir des 179 échantillons de matières fécales, un total de 158 (88,3%) isolats d'E. coli ont été obtenus. Des marqueurs du gène de virulence ont été détectés dans 18,4% (29/158) des isolats. Parmi les gènes étudiés codant pour la production d'entérotoxines, STb était le plus répandu (16/158, 10,13%), suivi de STa (12/158, 7,59%), tandis que le gène de la LT n'a pas été détecté. Le gène codant pour l'adhésine F4 était le seul détecté alors que l'adhésine F18 n'a pas été détectée dans les isolats. Sur l'analyse de régression logistique multiple, seul le niveau d'enseignement supérieur (OR=0,141; IC à 95%=0,30-0,666; p=0,013) et l'utilisation peu fréquente d'antibiotiques (OR=0,231, IC à 95 %=0,062-0,859; p=0,029) parmi les éleveurs, étaient les deux facteurs de protection significative des porcelets contre la diarrhée. Conclusion: Cette étude rapporte une prévalence élevée de marqueurs génétiques d'entérotoxines parmi les isolats d'E. coli chez les porcelets et a révélé le rôle potentiel de ces bactéries dans l'étiologie de la diarrhée et de la mortalité des porcelets en Ouganda. De plus, cette étude a identifié des facteurs de risque qui peuvent être utiles dans la formulation de stratégies de traitement et de contrôle de l'infection causée par ces bactéries. D'autres études sont nécessaires pour identifier plus d'adhésines que ces isolats d'E. coli utilisent pour la colonisation intestinale, une étape qui aidera à éclairer le développement de vaccins.

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