Int. J. Environ. Res. Public Health 2012, 9 897 in size. Based on the antigenic reactivity of the capsid proteins, these viruses have been classified into eight serotypes, 1–8 [11]. EVs, members of the family Picornaviridae, possess a single stranded positive sense RNA genome of 7.5 kb and have been classified into four species, Human enterovirus (HEV) A,B,C,D with more than 90 serotypes [12]. AiV of the genus Kobuvirus, family Picornaviridae consists of a single-stranded positive-sense RNA molecule of 8.2 kb nucleotides excluding a poly (A) tail. Based on the 3C-3D junction and VP1 regions, the AiV genome has been classified into three genotypes A, B and C [13]. In India, sporadic infections of gastroenteritis have been investigated extensively for enteric viruses. Rotaviruses followed by NoVs, enteric AdVs and HAstVs are the most frequently identified causative agents of viral gastroenteritis [10,14-18]. Although occurrence of outbreaks of gastroenteritis has been documented in the records of the State Surveillance Unit, Integrated Disease Surveillance Project, Maharashtra, investigations to unfold viral aetiology have been rarely carried out. In the present study, two outbreaks of acute gastroenteritis that occurred in southern Mumbai, western India in the months of March and October 2006 were investigated for multiple enteric viral agents to determine their contribution in causing gastroenteritis. 2. Experimental Section Mumbai is the capital of Maharashtra state and most populous city in India, with a total population of 18.4 million and a total area of 603.4 km2. Apart from one dam six major lakes supply water to the city [19]. Mumbai has a tropical climate, mostly warm and humid in nature. The occurrence of gastroenteritis outbreaks in southern Mumbai was reported in the months of March and October, 2006. 2.1. Epidemiological Investigation To ascertain the occurrence of outbreaks of gastroenteritis, medical record of all gastroenteritis cases referred to Gokuldas Tejpal Hospital (GTH) and Sir Jamshedjee Jeejeebhoy Hospital (JJH) from January to December, 2006, was examined and the information on age, gender, symptoms, date of onset and admission of patients was acquired. The number of gastroenteritis cases admitted to the pediatric and adult wards of GTH and JJH in the previous year was also recorded. Any inhabitant of the gastroenteritis affected localities, admitted for ≥3 loose or watery stools a day with or without vomiting, fever and abdominal pain at GTH during 13th–26th March (11–12 weeks), 2006 and at JJH during 5th–15th October (40–41 weeks), 2006 was considered an outbreak case. 2.2. Specimens Faecal specimens were collected from 72 (30 children ≤10 years, 5 adolescents aged 11–17 years and 37 adults ≥18 years) and 146 (61 children ≤10 years, 6 adolescents aged 11–17 years and 79 adults ≥18 years) patients hospitalized at GTH and JJH, respectively, during the outbreak periods. Thirty percent faecal suspensions were prepared in 0.01 M phosphate buffered saline (PBS), pH 7.4. The suspensions were centrifuged at 10,000 rpm for 10 min to remove the debris and supernatants were stored in aliquots at −70 °C until tested.