An outbreak of Norovirus infections associated with recreational lake water in Western Finland, 2014.

In July 2014, an outbreak of gastroenteritis occurred among visitors to lakes in Tampere, Finland. We conducted a retrospective cohort study using an internet-based survey, solicited by public announcement, to identify source of infection and to implement control measures. Of 1453 persons enrolled in the study, 244 met the case definition (attack rate, 17%). In the pooled univariate analysis, risk factors for gastroenteritis included getting water in the mouth while swimming (Risk ratio (RR) 3.32; 95% Confidence interval (CI), 2.36-4.68) and playing on the wet sand at the beach (RR 1.90; 95% CI 1.50-2.41). In a multivariable analysis (logistic regression), the source of the infection was likely at two lakes (lake A Odds ratio (OR) 1.66; 95% CI 1.15-2.39 and lake B, OR 2.35; 95% CI 1.49-3.72). Norovirus (NoV) was found in 19 stool samples. All water samples from implicated beaches had acceptable values of fecal indicator bacteria and were negative for NoV. The likely source of the outbreak was lake-water contaminated with NoV at two popular lakes. Closure of swimming beaches, advice on hygienic precautions and rapid outbreak alerts were efficient in controlling the outbreak. Results suggest a need for new indicators of water quality and development of evidence-based recommendations regarding timing of safe reopen of recreational water venues associated with outbreaks.

Comparative studies on N'Dama and zebu cattle following repeated infections with Trypanosoma congolense.

Twenty N'Dama and eight zebu cattle were inoculated intradermally with bloodstream forms of a cloned strain of Trypanosoma congolense originating from East Africa. All inoculated cattle became parasitaemic. Zebus showed consistently higher levels of parasitaemia and lower packed red cell volume (PCV) percentages than did N'Damas. Three of the eight zebus required treatment when high numbers of trypanosomes were present in the blood and PCV values dropped below 15 per cent. None of the N'Dama cattle needed treatment. Statistical analysis was performed on the data to assess the variability of parasitaemia and PCV levels before and during infection of the N'Dama cattle. The variation in PCV values was large between individuals during the early stages of the disease and diminished as infection continued. After trypanocidal drug treatment and a recovery period of 14 months, the same animals were inoculated intradermally with T congolense bloodstream forms isolated and cloned in The Gambia. Differences in susceptibility to the ensuing disease were apparent when comparing N'Dama and zebu cattle. Five zebu cattle needed trypanocidal drug treatment, while none of the N'Damas needed drug intervention. Ranking the 20 infected N'Damas according to average PCV levels revealed that the animals responded similarly to both infections.