Contaminated pond water favors cholera outbreak at haibatpur village, purba medinipur district, west bengal, India.

Health workers reported an increased number of diarrhea cases at Haibatpur village on June 17, 2012. This outbreak was investigated with the following objectives: to confirm the existence of diarrhea outbreak, to find out the risk factors, and propose control measures. Cases were listed; spot map and epidemic curve were drawn. Attack rate was calculated by age and sex and risk factors were found out by calculating odds ratio (OR) with 95% confidence interval (CI). Rectal swabs were taken and water specimens were collected for laboratory test. Forty-one cases of patients were identified with overall attack rate (AR) was 5% (41/780). AR among men was higher 6% (25/404) than women. There was no death. V. cholerae 01 Eltor Ogawa was isolated from one (1/4) stool specimen. Spot map showed cases clustered around two ponds which were contaminated with coliform organisms. The underground water was a bit saline in nature. Using pond water for preparation of fermented rice (Panta Bhat) (OR 4.73, 95% CI 1.69-13.51), washing utensil in pond water (OR 7.31, 95% CI 1.77-42.29) were associated with cholera outbreak. Health education was done to villagers. Disinfection of two ponds with bleaching powder was done. We proposed supplying of safe drinking water and repairing defective deep tube well to village.

Dengue fever in a rural area of West Bengal, India, 2012: an outbreak investigation.

BACKGROUND: During September 2012, an increased number of fever cases was reported from Ramnagar-II block, Purba Medinipur district. This study investigated the outbreak, with the following objectives: to describe the distribution of fever cases, to determine the risk factors and to recommend preventive measures. MATERIALS AND METHODS: The clinical features, date of onset and outcome of all cases of fever were listed. Blood specimens were collected from affected patients and sent for serological examination. An epidemic curve was plotted and environmental and entomological surveys were carried out. RESULTS: There was a total of 100 cases, of which 56% (56/100) were men.Among the four villages studied, the highest number of cases was from Gopalpur 37% (37/100), followed by Badalpur 26% (26/100); 19% (19/100) of cases had a history of migration from dengue-endemic areas. The majority of cases were in age group 15-45 years - 52% (52/100), followed by the age group >45 years - 28% (28/100). All the cases had history of fever (100%), followed by myalgia - 82%, headache - 78%, and retro-orbital pain - 73%. The outbreak started on 7 September 2012, peaked on 18 September, then gradually declined and no further cases were noted after 28 September 2012. Seventy-nine percent (79/100) of cases were NS1 test positive (non-structural antigen-1) and 72% (13/18) cases were positive on a dengue monoclonal antibody (IgM) capture enzyme-linked immunosorbent assay (MAC-ELISA) test. All recovered except one (case-fatality ratio: 1%). The values for Household Index, Container lndex and Breteau Index of the four villages were: Badalpur, 3%, 10% and 5%; Gopalpur, 13%, 23% and 18%; Ramchandrapur, 9%, 11%, and 13%; and Tajpur, 2%, 2% and 2%. CONCLUSION: The outbreak was probably due to dengue fever. The study led to a recommendation to destroy water containers and use mosquito nets. The outbreak was controlled.

An outbreak of pandemic influenza A (H1N1) in Kolkata, West Bengal, India, 2010.

BACKGROUND & OBJECTIVES: An increased number of cases with influenza like illness (ILI) were reported in Greater Kolkata Metropolitan Area (GKMA) during July and August 2010. We investigated these cases to confirm the outbreak, describe the distribution of patients and propose control measures. METHODS: A suspected case of influenza like illness (ILI) was defined as acute onset of fever (>38°C) with cough or sore throat and a confirmed case as ILI case with throat swab positive for influenza A (H1N1) on RT-PCR. The demographic and clinical details were collected from patients attending the swine flu OPD of Infectious Disease Hospital, Kolkata, during July 5 to August 16, 2010. RESULTS: Overall 440 patients with ILI attended the swine flu OPD of Infectious Disease and Bengal General hospital during the study period, of which 129 were positive for influenza A (H1N1). Four patients died (case fatality ratio: 0.90%). Besides fever, common symptoms included cough (73%), running nose (54%), sore throat (43%), respiratory distress (25%) and diarrhoea (4%). Forty seven (11%) patients (including the four who died) had co-morbidities. The outbreak started on July 10, peaked on July 24 and subsided by August 14, 2010. A total of 372 (85%) patients were from GKMA. Majority (n=168, 45%) of the cases from GKMA were from 6 boroughs of Kolkata Municipal Areas. INTERPRETATION & CONCLUSIONS: An outbreak of influenza A (H1N1) occurred in Kolkata predominantly affecting young and middle aged population. State health authorities implemented several interventions to limit the outbreak including training of health care providers in case management and infection control, vaccination of health care workers, creation of isolation wards and administration of oseltamivir to ILI patients, and community health education about social distance and personal hygiene measures.

Waterborne cholera outbreak following Cyclone Aila in Sundarban area of West Bengal, India, 2009.

Following Cyclone Aila, a block of Sundarban area, West Bengal, India, reported an increased number of diarrhoea cases at the end of May 2009. This study was performed to identify the agent and source of the outbreak as well as to propose control measures. The outbreak is described by time, place and person. A matched case-control study was conducted and rectal swabs and water specimens were collected. In total, 1076 probable case patients and 14 deaths (attack rate 44/10 000) were identified. Vibrio cholerae El Tor Ogawa was isolated from two of five probable case patients' stool specimens. The outbreak started in the fourth week of May, with two peaks in the second and fourth weeks of June, and lasted until August 2009. Compared with controls, cases were more likely to drink non-chlorinated piped water [matched odds ratio (MOR)=16, 95% CI 4.9-51; population attributable fraction 58%) and were less likely to drink chlorine-treated water (MOR=0.06, 95% CI 0.02-0.18). Villagers broke the water pipelines near their houses for easy access to water. Piped water specimens and stored drinking water were positive for faecal contamination. Contaminated drinking water was the probable source of the cholera outbreak. Repairing the pipelines, chlorination at household level and educating villagers regarding the danger of breached water pipe connections controlled the outbreak.

Cholera outbreak secondary to contaminated pipe water in an urban area, West Bengal, India, 2006.

Outbreaks of cholera are common in West Bengal. In April 2006, Garulia municipality reported a cluster of diarrhea cases. We investigated this cluster to identify the etiological agent, source of transmission and propose control measures. We defined a case of diarrhea as occurrence of > or =3 loose/watery stools a day among the residents of Garulia since April 2006. We searched for cases of diarrhea in health care facilities and health camp. We conducted a gender- and age-matched case-control study to identify risk factors. We inspected the sanitation and water supply system. We collected rectal swabs from diarrhea patients and water specimens from the affected areas for laboratory investigation. Two hundred and ninety-eight cases of diarrhea were reported to various health care facilities (attack rate: 3.5/1000, no deaths). The attack rate was highest among children (6.4/1000). Vibrio cholerae El Tor O1 Inaba was isolated from two of 7 rectal swabs. The outbreak started on 10 April 2006, peaked on 26 April and lasted till 6 May. Cases clustered in an area distal to leaking water pipelines. Drinking municipal water exclusively was significantly associated with the illness (OR 13, 95% CI=6.5-27). Eight of the 12 water specimens from the affected area had fecal contamination and poor chlorine content. This outbreak was due to a contaminated municipal piped water supply and V. cholera 01 Inaba was possibly the causative organism.

A typhoid fever outbreak in a slum of South Dumdum municipality, West Bengal, India, 2007: evidence for foodborne and waterborne transmission.

BACKGROUND: In April 2007, a slum of South Dumdum municipality, West Bengal reported an increase in fever cases. We investigated to identify the agent, the source and to propose recommendations. METHODS: We defined a suspected case of typhoid fever as occurrence of fever for > or = one week among residents of ward 1 of South Dumdum during February - May 2007. We searched for suspected cases in health care facilities and collected blood specimens. We described the outbreak by time, place and person. We compared probable cases (Widal positive > or = 1:80) with neighbourhood-matched controls. We assessed the environment and collected water specimens. RESULTS: We identified 103 suspected cases (Attack rate: 74/10,000, highest among 5-14 years old group, no deaths). Salmonella (enterica) Typhi was isolated from one of four blood specimens and 65 of 103 sera were > or = 1:80 Widal positive. The outbreak started on 13 February, peaked twice during the last week of March and second week of April and lasted till 27 April. Suspected cases clustered around three public taps. Among 65 probable cases and 65 controls, eating milk products from a sweet shop (Matched odds ratio [MOR]: 6.2, 95% confidence interval [CI]: 2.4-16, population attributable fraction [PAF]: 53%) and drinking piped water (MOR: 7.3, 95% CI: 2.5-21, PAF-52%) were associated with illness. The sweet shop food handler suffered from typhoid in January. The pipelines of intermittent non-chlorinated water supply ran next to an open drain connected with sewerage system and water specimens showed faecal contamination. CONCLUSION: The investigation suggested that an initial foodborne outbreak of typhoid led to the contamination of the water supply resulting in a secondary, waterborne wave. We educated the food handler, repaired the pipelines and ensured chlorination of the water.