Academic journal article Bulletin of the World Health Organization

A Large Waterborne Viral Hepatitis E Epidemic in Kanpur, India

Academic journal article Bulletin of the World Health Organization

A Large Waterborne Viral Hepatitis E Epidemic in Kanpur, India

Article excerpt

In 1991 the largest epidemic of viral hepatitis E yet reported occurred in Kanpur (population, 2.1 million), India. The incidence of icteric hepatitis from December 1990 to April 1991 among the inhabitants of 420 randomly sampled houses in seven of the city's 50 wards was 3.76% (138 out of 3666 individuals), i.e., an estimated 79 091 persons in the city as a whole were affected. The attack rate was higher for males than females (5.3% versus 3.3%; P = 0.013) and for adults than children aged <10 years (4.26% versus 1.29%; P = 0.0006). The incidence of hepatitis was higher in those city wards that were supplied with drinking-water consisting of a mixture of river Ganges and tubewell water than in those wards supplied only with tubewell water (5.6% versus 1.2%; P = [10.sup.-6]). In the mixed-water areas, the incidence decreased as the drinking-water source changed from only tap to both tap and handpump, to only handpump (7.8%, 6.8%, and 4.3% respectively; P = 0.023). None of the sera collected from 41 hepatitis patients during the epidemic showed evidence of hepatitis virus A or B.

There were two peaks in the epidemic (in February and April 1991). The first peak was probably caused by faecal contamination of river water, indicated by water analysis data, and the second, by inadequate chlorination of water in a reservoir. There was no evidence of secondary intrafamilial spread.

Epidemics of hepatitis occur frequently in the Indian subcontinent and are mostly due to the enterically transmitted hepatitis E virus[1-3]. The largest previously reported epidemic of viral hepatitis occurred in Delhi in 1955-56, when an estimated 29 300 persons were affected with jaundice[4]. Recently, we carried out an epidemiological investigation of a much larger epidemic of hepatitis in the city of Kanpur and report here our results.


Pilot survey

Following reports of widespread hepatitis in Kanpur in the second week of April 1991, we conducted a pilot survey on 19-20 April in one locality of the city using a systematic sampling technique, with municipal house numbers as the unit for randomization. In those instances where a house was locked or was non-residential, the next-nearest house was surveyed. A total of 54 families in a heavily affected area were visited; the incidence of icteric hepatitis in the sampled population between December 1990 and the pilot survey in late April 1991 was 10.6% (35 of 331 family members). Widespread public and medical opinion in the city suggested that those areas of Kanpur that were supplied with water from the river Ganges had higher incidences of hepatitis. Since most of the previously reported epidemics of hepatitis in India have been caused by contaminated water supplies[3], we carried out a detailed field survey to determine the relationship between the water supply and the incidence of hepatitis in Kanpur and to quantify the magnitude of the problem presented by hepatitis in the city.

Kanpur city and its water supply system

Kanpur city in the northern state of Uttar Pradesh is a major centre of industry and is the eighth most populous city in India. According to provisional data released by the Census of India, its population on 1 March 1991 was 2 103 483[5]. The city has a linear-type development along the right bank of the river Ganges.

Kanpur has two major sources of water supply: surface water from the river Ganges, to the north of the city, and the Lower Ganges Canal, to the south; and deep tubewells. Kanpur is divided into the following districts for the purposes of water supply; the city, south, east, and west service districts (Fig. 1). Municipal water for the first two of these districts is mainly drawn from the river Ganges. Approximately 150 million litres of water are pumped daily from the intake point at Bhaironghat to the Bainajhaber water treatment plant, where it is mixed with approximately 70 million litres of water from the Lower Ganges Canal. …

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