Background. An outbreak of gastroenteritis of etiologically unspecified origin and an outbreak of Salmonellosis occurred simultaneously in September 2011 in Tržič. The purpose of the investigation of both outbreaks was to identify the most probable source and the mode of transmission and to implement preventive measures. Methods. In two retrospective case-control studies, the association between gastroenteritis of etiologically unspecified origin or Salmonellosis and food from a restaurant or drinking tap water were tested by univariate and multivariate analysis. The subject in the first study was a sick person with salmonellosis, and the subject in the second study was a resident that developed diarrhoea and/ or vomiting. Cases were reported by doctors, and controls were selected from healthy persons who responded to the questionnaire. Results. A person exposed to food from the restaurant had a 24.8 times higher odds ratio (univariate analysis OR 24.8, 95% CI 7.5 to 82.3, p <0.05; multivariate analysis OR 14.7, 95% CI 3.5 - 61.3, p <0.05) for salmonellosis than non-exposed. A resident exposed to tap water from specific water source had a 3.4 times higher odds ratio (univariate analysis of OR 3.4, 95% CI 2.2 to 5.1 is p <0.05, multivariate analysis of RO 2.9, 95% CI 1, 7 to 5.3, p <0.05), for gastroenteritis of unspecific etiology than non-exposed. The dose response relationship was also statistically significant. Conclusion. Analytical cases - controls studies confirmed a causal relationship between salmonellosis and food from the specific restaurant and the causal relationship between gastroenteritis of etiologically unspecified origin and drinking tap water from specific water source. Salmonella enteritidis may have entered into the restaurant through tap water Uvod. Izbruh gastroenteritisa neopredeljene etiologije in izbruh salmoneloze sta bila hkrati v Tržiču septembra 2011. Namen preiskave izbruhov je bil odkriti izvor in poti prenosa okužbe s ciljem, da se sprejmejo ukrepi za prekinitev širjenja. Metode. V dveh retrospektivnih študijah primerov in kontrol je bila z univariatnimi in multivariatnimi analizami testirana povezava med gastroenteritisom neopredeljene etiologije oziroma salmonelozo in uživanjem hrane v gostilni ali pitjem vodovodne vode. Primer v prvi študiji je bil oboleli s salmonelozo, primer v drugi študiji pa je bil vsak občan z drisko in/ali bruhanjem. Primere obolelih so prijavili zdravniki; kontrole so bile izbrane med zdravimi osebami, ki so vrnile izpolnjeni vprašalnik. Rezultati. Osebe, izpostavljene hrani v gostilni, so imele 24,8-krat višje obete za obolevanje za salmonelozo kot neizpostavljeni (univariatna analiza RO 24,8; 95 % IZ 7,5-82,3; p < 0,05; multivariatna analiza RO 14,7; 95% IZ 3,5-61,3, p < 0,05). Občani, ki so pili vodo iz določenega vodnega vira, so imeli 3,4-krat višje obete, da so oboleli za gastroenteritisom neopredeljene etiologije kot neizpostavljeni (univariatna analiza RO 3,4; 95 % IZ je 2,2-5,1; p < 0,05; multivariatni analizi RO 2,9; 95 % IZ 1,7-5,3; p < 0,05). Statistično značilna je bila tudi povezava med obolevanjem in količino popite pitne vode. Zaključki. Z analitičnima študijama primerov in kontrol smo potrdili vzročno povezanost med salmonelozo in prehranjevanjem v določeni gostilni ter povezanost med gastroenteritisom neopredeljene etiologije in pitjem vodovodne vode iz določenega vodnega vira. Mogoč je vnos Salmonelle enteritidis v gostilno prek vodovodne vode