|Year : 2007 | Volume
| Issue : 4 | Page : 277-279
Epidemiological investigation of an outbreak of infectious hepatitis in Dakor town
A Bhagyalaxmi, M Gadhvi, BS Bhavsar
Department of Preventive and Social Medicine, B. J. Medical College, Ahmedabad, India
|Date of Submission||19-Apr-2005|
|Date of Acceptance||12-Apr-2007|
B/403, Spectrum Tower, Opp. Police Stadium, Shahibaug, Ahmedabad - 380 004
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Bhagyalaxmi A, Gadhvi M, Bhavsar B S. Epidemiological investigation of an outbreak of infectious hepatitis in Dakor town. Indian J Community Med 2007;32:277-9
|How to cite this URL:|
Bhagyalaxmi A, Gadhvi M, Bhavsar B S. Epidemiological investigation of an outbreak of infectious hepatitis in Dakor town. Indian J Community Med [serial online] 2007 [cited 2020 Aug 12];32:277-9. Available from: http://www.ijcm.org.in/text.asp?2007/32/4/277/37694
Acute viral hepatitis is a major public health issue in the developing nations that have inadequate sanitary conditions. Hepatitis A virus causes relatively benign diseases and does not constitute a major public health issue. Hepatitis E virus is transmitted enterically, most frequently in epidemic outbreaks. Epidemics of hepatitis E occur frequently in developing countries especially in the Indian subcontinent where poor socio-economic and hygienic conditions lead to epidemics by recurrent contamination of water supplies.
An unusual increase of jaundice cases was noticed in Dakor town in the last week of January 2004. The health department was informed, and an investigation team visited the town immediately. The details of the investigation of the jaundice cases are presented in this study.
| Materials and Methods|| |
Background information of the town
Dakor taluka of Kheda district in Gujarat state is a pilgrimage centre for the devotees of Lord Krishna. The population of this town was 24,195 as per 2001 census.
There are eight wards in the town. More than 90% of the people receive their water supply from the Nagarpalika; the water is supplied by four bore wells and four water tanks situated in the different wards of the town.
Epidemiological data were collected from (1) hospital records, (2) active surveillances, and (3) the survey sample.
The investigation team visited community heath centers (CHC) and four hospitals to examine the admitted patients. Blood samples were collected from seven patients to estimate serum bilirubin levels, alkaline phosphatase, SGOT, SGPT, and markers of hepatitis. The team also visited the affected areas to carry out environmental surveys. Water samples from Municipal water sources and private bores were collected for bacteriological examination. Estimation of residual chlorine was performed at different levels of the water distribution system.
Door-to-door survey was conducted to gain information on the attack rate and the different sources of water supply. Four wards of the town were randomly selected, and 10% of the houses in the selected wards comprised the study sample. All households in the selected houses were included. A total of 180 houses were covered in the sample survey, and 852 households were studied. The data was analyzed using Epi Info 2002.
| Results|| |
A total of 454 jaundice cases were reported in Dakor town in January 2004. Information on the reported cases of jaundice along with their date of onset is shown in [Figure - 1]. Seasonal variation in the jaundice cases was not analyzed since the data from the previous year were not available. Few cases of jaundice were reported in the first and the second weeks of January; then a sudden increase in the number of cases was observed from the third week of January reaching peak in mid-February 2004. A gradual decline in the number of cases was observed there-after. The epidemic curve showed a prolonged epidemic with two peaks of incidence.
Jaundice cases were reported from all the eight wards of the town. The maximum attack rate was observed in ward no. 7, followed by ward no. 4. During epidemic 66 cases of Jaundice were reported from the nearby villages. Maximum cases (252) were young adults (age range, 20-40 years) where the mean age of the females was 37.014 ± 12.23 years and that of the males was 33.03 ± 12.84 years [Table - 1]. The incidence rate of jaundice in males was 25.8/1000 and in females was 9.36/1000. (Z = 10.37, P < 0.001). No deaths were reported.
Most of the cases presented with the signs and symptoms of fever, anorexia, and yellowish sclera and urine. The bore water supplied to the town was stored in four different tanks. The valve mechanism of these tanks was not functioning; therefore, the water in the tanks was mixed up. The water in the tanks was chlorinated by using bleaching powder. On estimating the residual chlorine at different levels, more than 2 ppm of chlorine residual was estimated in the water tanks. However, the chlorine residual level was 0.2 ppm in the households who added chlorine tablets to their drinking water, and no residual chlorine was observed in the water used for other purposes.
A significant association was observed between the attack rate of the jaundice cases and the sources of water supply. The proportion of jaundice cases among those who received water from the Nagarpalika was found to be 7.8% (56/720) and of those who received water from private bores was 2.3% (3/132) (Z = 3.3, P < 0.01).
The drainage system was being repaired from the past one month (from December 2003) due to some problem in the system. Simultaneously, some areas of the town were being dug up to facilitate cable connection.
Blood samples that were tested for markers of viral hepatitis were positive for anti-HEV. Bacteriological analysis of the water samples confirmed the sewage contamination of the water. Klebsiella pneumoniae (>180 MPN/100 ml) were found in the samples taken from the water supplied by the Nagarpalika.
As soon as the epidemic was noted (in the last week of January), all water sources were super-chlorinated. Chlorine tablets were distributed to all houses in the town and were also made available from the road-side vendors. Simultaneously, extensive health education was provided. Five health workers were deployed to perform active surveillance of the cases and one epidemic medical officer (EMO) was appointed to monitor the activities. Leakages and repairs in the distribution system and tanks were investigated by the investigation team and a meeting was held with the members of the Nagarpalika. It took 15-20 days to complete the entire repair work.
| Discussion|| |
In this study, the overall incidence rate of hepatitis E was found to be 18.76 per 1000 population where the male:female ratio was 2.8:1. Similar findings were observed during the investigation of hepatitis outbreak in Ahmedabad city during 1975-1976 (the incidence rate of hepatitis E was 14 per 1000 population, male:female ratio was 2.8:1). High incidence of infective hepatitis (34.6/1000) was reported in Tirupati town in 1981 with male preponderance. Age distribution of cases was almost similar to that reported in most previous epidemics of hepatitis E.
Sudden rise in the number of jaundice cases suggested epidemic of hepatitis. Most of the affected persons were young adults indicates the transmission of hepatitis E which was also confirmed by serological examination. The simultaneous repair of the drainage system and digging for cable connection might have caused the damage to the water pipelines and resulted in the contamination of water. The attack rates were in relation to the source of the water supply of the affected households; this lead to the conclusion that the municipal water supply was contaminated due to the outbreak of hepatitis in the study area. This finding was also supported by the bacteriological analysis of the water sample, which confirmed sewage contamination.
The attack rate was highest in ward no. 7, followed by ward no. 4; however, the report of cases from all the wards suggested multiple contamination points. Hepatitis E is rarely transmitted from person-to-person. Epidemics of hepatitis E usually occur in unimodal outbreaks with a highly compressed curve of incidence or prolonged epidemics with multiple peaks of incidence.
Although prompt actions like super-chlorination of water, distribution of chlorine tablets, and identification and repair of leakages were taken immediately after the epidemic was noted, the number of cases started to decline from mid-March. This could be due to the long incubation period of hepatitis E (2-9 weeks) and probably because the identification and repair of leakage took a long time, during this period the contamination must have continued. Occurrence of 66 jaundice cases in the neighboring villages could be attributed to population mobility due to commercial activities. Information from these cases could not be acquired.
Hepatitis E virus causes a major public health issue in India. A study by Tandon et al. reported hepatitis E virus as the most important cause of all the clinical types of hepatitis commonly found in India.
The limitation of the present study was that only seven blood samples were tested for markers of hepatitis (as the investigation was very expensive).
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[Figure - 1]
[Table - 1]