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

Bhunia R, Hutin Y, Ramakrishnan R, Pal N, Sen T, Murhekar M - BMC Public Health (2009)

Bottom Line: We compared probable cases (Widal positive > or = 1:80) with neighbourhood-matched controls.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.We educated the food handler, repaired the pipelines and ensured chlorination of the water.

View Article: PubMed Central - HTML - PubMed

Affiliation: Field Epidemiology Training Programme, National Institute of Epidemiology (Indian Council of Medical Research), Chennai, India. rbhunia@gmail.com

ABSTRACT

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.

Show MeSH

Related in: MedlinePlus

Distribution of possible cases (Fever of at least one-week duration) in the affected area of ward 1, South Dumdum municipality, "North 24 Parganas" district, West Bengal, India, February–May 2007 (N = 103).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC2683821&req=5

Figure 2: Distribution of possible cases (Fever of at least one-week duration) in the affected area of ward 1, South Dumdum municipality, "North 24 Parganas" district, West Bengal, India, February–May 2007 (N = 103).

Mentions: The average reported monthly rate of fever of >= one-week duration ranged between 4 and 8 per 10,000 population during 2004 and 2007 in the urban health sub-centre of ward 1. From February to April 2007, we identified 103 suspected cases (Incidence: 74 per 10,000). Clinical symptoms included malaise, loss of appetite, headache, cough, constipation, diarrhea and rash (Table 1). The median age of suspected case-patients was 13 years (Range 2–77), six percent of suspected case-patients had been hospitalized and there were no deaths. The attack rate among the 5 to 14 years of age was 151 per 10,000, twice higher than among other age groups (Table 2). Trawling questionnaires yielded frequent exposures to a sweet shop in ward 1 among suspected case-patients. The outbreak started on 13 February, had two peaks on during the last week of March and second week of April and ended on 27 April (Figure 1). Suspected cases clustered around three public taps located about 50 metres away from the sweet shop (Figure 2). Suspected case-patients who reported consumption of food from the sweet shop had an earlier date of onset than others (Figure 1). Based on (1) the distribution of suspected cases over time, (2) the trawling questionnaires that pointed to a sweet shop and (3) the geographical distribution of suspected cases around a specific source of water supply, we generated the hypothesis that two sources i.e. food and tap water could be the source of the outbreak.


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

Bhunia R, Hutin Y, Ramakrishnan R, Pal N, Sen T, Murhekar M - BMC Public Health (2009)

Distribution of possible cases (Fever of at least one-week duration) in the affected area of ward 1, South Dumdum municipality, "North 24 Parganas" district, West Bengal, India, February–May 2007 (N = 103).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2683821&req=5

Figure 2: Distribution of possible cases (Fever of at least one-week duration) in the affected area of ward 1, South Dumdum municipality, "North 24 Parganas" district, West Bengal, India, February–May 2007 (N = 103).
Mentions: The average reported monthly rate of fever of >= one-week duration ranged between 4 and 8 per 10,000 population during 2004 and 2007 in the urban health sub-centre of ward 1. From February to April 2007, we identified 103 suspected cases (Incidence: 74 per 10,000). Clinical symptoms included malaise, loss of appetite, headache, cough, constipation, diarrhea and rash (Table 1). The median age of suspected case-patients was 13 years (Range 2–77), six percent of suspected case-patients had been hospitalized and there were no deaths. The attack rate among the 5 to 14 years of age was 151 per 10,000, twice higher than among other age groups (Table 2). Trawling questionnaires yielded frequent exposures to a sweet shop in ward 1 among suspected case-patients. The outbreak started on 13 February, had two peaks on during the last week of March and second week of April and ended on 27 April (Figure 1). Suspected cases clustered around three public taps located about 50 metres away from the sweet shop (Figure 2). Suspected case-patients who reported consumption of food from the sweet shop had an earlier date of onset than others (Figure 1). Based on (1) the distribution of suspected cases over time, (2) the trawling questionnaires that pointed to a sweet shop and (3) the geographical distribution of suspected cases around a specific source of water supply, we generated the hypothesis that two sources i.e. food and tap water could be the source of the outbreak.

Bottom Line: We compared probable cases (Widal positive > or = 1:80) with neighbourhood-matched controls.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.We educated the food handler, repaired the pipelines and ensured chlorination of the water.

View Article: PubMed Central - HTML - PubMed

Affiliation: Field Epidemiology Training Programme, National Institute of Epidemiology (Indian Council of Medical Research), Chennai, India. rbhunia@gmail.com

ABSTRACT

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.

Show MeSH
Related in: MedlinePlus