context: An unexpected increase in gastroenteritis cases was reported by healthcare workers on the KwaZulu-Natal Coast, South Africa, January 2017 with >600 cases seen over a 3-week period. A case-control study was conducted to identify the source and risk factors associated with the outbreak so as to recommend control and prevention measures. Record review identified cases and controls and structured-telephonic interviews were conducted to obtain exposure history. Stool specimens were collected from 20 cases along with environmental samples and both screened for enteric pathogens. A reported sewage contamination event impacting the lagoon was the likely source with person-to-person spread perpetuating the outbreak. On 5 January 2017, the Outbreak Response Unit (ORU) of the National Institute for Communicable Diseases (NICD), SA, was alerted to a high number of persons falling ill with gastrointestinal symptoms (diarrhoea and/or vomiting) on the coast of KZN Province. The alert from health authorities in the KZN Province indicated that between 14 December 2016 and 5 January 2017, 690 people presented with gastrointestinal symptoms at a private hospital on the KZN south coast. Based on the available information at the time, which included local newspaper and online articles that reported a sewage spillage into a nearby lagoon; the investigating team hypothesised that contamination of a coastal lagoon could have led to the outbreak. The outbreak occurred within an urban community on the south coast of KZN Province during December 2016 and January 2017. A case-control study was conducted, with a case defined as a person of any age who presented to the private hospitals emergency department between 19 December 2016 and 6 January 2017 with an acute onset of diarrhoea and/or vomiting. Twenty acute phase stool specimens were collected from cases presenting to the hospital between 6 and 10 January 2017 and sent cooled to the Centre for Enteric Diseases (CED), NICD, for testing. Water samples were collected from the lagoon and a nearby wastewater treatment works discharge (final effluent), which drains into a river that flows into the lagoon (Fig. 1). A total of 311 cases and 126 controls were identified. The median age for the cases was 21 years (interquartile range 1040 years). The most common symptoms were vomiting (85%; 133/157), diarrhoea (73%; 115/157) and abdominal cramps (31%; 49/157). Of the 20 clinical specimens tested, 11 (55%) tested positive for NoV; nine were positive for NoV GI, while two were positive for NoV GII. Aeromonas, enterovirus and EPEC were also detected in one NoV GI-positive specimen and STEC in another NoV GI-positive specimen. Environmental samples The total coliform and thermotolerant (faecal) coliform counts in the lagoon water were 2.39* 10^4 and 9.5* 10^3 cfu/100 ml, respectively. The E. coli level was 1.93* 10^3 cfu/100 ml. These data support the hypothesis that the lagoon was the source of the outbreak among holiday-makers on the KZN Coast. The lagoon was reportedly contaminated by the wastewater treatment works effluent, which drained into the river flowing into the lagoon. 
  
answers: {'answer_start': [1529], 'text': ['during December 2016 and January 2017']}