Epidemiological Investigation of an Outbreak of Infectious Hepatitis in Dakor Town
Author(s): A Bhagyalaxmi, M Gadhvi, BS Bhavsar
Vol. 32, No. 4 (2007-10 - 2007-12)
ISSN No. 0970-0218
A Bhagyalaxmi, M Gadhvi, BS Bhavsar
Acute viral hepatitis is a major public health issue in
the developing nations that have inadequate sanitary
conditions.1 Hepatitis A virus causes relatively benign
diseases and does not constitute a major public health
issue.2 Hepatitis E virus is transmitted enterically, most
frequently in epidemic outbreaks.3 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.5
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.
Figure 1: Distribution of cases as per date of onset (1st January
to 18th March 2004)
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).5 High incidence of infective hepatitis
(34.6/1000) was reported in Tirupati town in 1981 with
male preponderance.1 Age distribution of cases was
almost similar to that reported in most previous epidemics
of hepatitis E.5
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.4 Epidemics
of hepatitis E usually occur in unimodal outbreaks with
Bhagyalaxmi A, et al.: Outbreak of infectious hepatitis a highly compressed curve of incidence or prolonged
epidemics with multiple peaks of incidence.4
Table 1: Age and sex distribution of the Jaundice cases
Age in years
Male
Female
Total
No.
%
%
No.
%
No.
0-9
1
0.3
-
-
1
0.22
10-19
61
17.8
20
17.9
81
17.84
20-29
109
31.9
40
35.7
149
32.81
30-39
77
22.5
26
23.2
106
23.34
40-49
62
18.6
17
15.2
79
17.40
50-59
23
6.7
8
7.1
31
6.82
>60
9
2.6
1
0.9
10
2.20
Total
342
100.00
112
100.00
454
100.00
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.2 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).
References
- Singh S, Mohanty A, Joshi YK, Deka D, Mohanty S, Panda
KS. Mother to child transmission of Hepatitis E virus. Indian
J Pediatr 2003;30:37-9.
- Tandon BN, Gandhi MB, Joshi YK, Irshad M, Gupta H.
Hepatitis virus-non-A and non B-the cause of a major public
Health problem in India. Bull WHO 1985;63:931-4.
- Kumar. S. Therapy of viral hepatitis: Current approaches.
Indian J Clin Pract 2001;12:5.
- Hepatitis E: From hypothesis to reality. Indian J Gastroenterol
1994;13:39-43.
- Srinivasan MA, Banerjee K, Pandya PG, Kotak RR, Pandya
PM, Desai NJ, et al. Epidemiological investigations of an
outbreak of infectious hepatitis in Ahmedabad city during
1975-76. Indian J Med Res 1978;67:197-206.
Department of Preventive and Social Medicine, B. J. Medical
College, Ahmedabad, India
Correspondence to:
Dr. A. Bhagyalaxmi,
B/403, Spectrum Tower, Opp. Police Stadium, Shahibaug,
Ahmedabad – 380 004, India.
E-mail: bhagya_mardi(at)yahoo.com
Received: 19.04.05
Accepted: 12.04.07
ISSN No. 0970-0218
A Bhagyalaxmi, M Gadhvi, BS Bhavsar
Acute viral hepatitis is a major public health issue in the developing nations that have inadequate sanitary conditions.1 Hepatitis A virus causes relatively benign diseases and does not constitute a major public health issue.2 Hepatitis E virus is transmitted enterically, most frequently in epidemic outbreaks.3 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.5
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.
Figure 1: Distribution of cases as per date of onset (1st January to 18th March 2004)
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).5 High incidence of infective hepatitis (34.6/1000) was reported in Tirupati town in 1981 with male preponderance.1 Age distribution of cases was almost similar to that reported in most previous epidemics of hepatitis E.5
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.4 Epidemics of hepatitis E usually occur in unimodal outbreaks with Bhagyalaxmi A, et al.: Outbreak of infectious hepatitis a highly compressed curve of incidence or prolonged epidemics with multiple peaks of incidence.4
Table 1: Age and sex distribution of the Jaundice cases
| Age in years | Male | Female | Total | |||
|---|---|---|---|---|---|---|
| No. | % | % | No. | % | No. | |
| 0-9 | 1 | 0.3 | - | - | 1 | 0.22 |
| 10-19 | 61 | 17.8 | 20 | 17.9 | 81 | 17.84 |
| 20-29 | 109 | 31.9 | 40 | 35.7 | 149 | 32.81 |
| 30-39 | 77 | 22.5 | 26 | 23.2 | 106 | 23.34 |
| 40-49 | 62 | 18.6 | 17 | 15.2 | 79 | 17.40 |
| 50-59 | 23 | 6.7 | 8 | 7.1 | 31 | 6.82 |
| >60 | 9 | 2.6 | 1 | 0.9 | 10 | 2.20 |
| Total | 342 | 100.00 | 112 | 100.00 | 454 | 100.00 |
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.2 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).
References
- Singh S, Mohanty A, Joshi YK, Deka D, Mohanty S, Panda KS. Mother to child transmission of Hepatitis E virus. Indian J Pediatr 2003;30:37-9.
- Tandon BN, Gandhi MB, Joshi YK, Irshad M, Gupta H. Hepatitis virus-non-A and non B-the cause of a major public Health problem in India. Bull WHO 1985;63:931-4.
- Kumar. S. Therapy of viral hepatitis: Current approaches. Indian J Clin Pract 2001;12:5.
- Hepatitis E: From hypothesis to reality. Indian J Gastroenterol 1994;13:39-43.
- Srinivasan MA, Banerjee K, Pandya PG, Kotak RR, Pandya PM, Desai NJ, et al. Epidemiological investigations of an outbreak of infectious hepatitis in Ahmedabad city during 1975-76. Indian J Med Res 1978;67:197-206.
Department of Preventive and Social Medicine, B. J. Medical College, Ahmedabad, India
Correspondence to:
Dr. A. Bhagyalaxmi,
B/403, Spectrum Tower, Opp. Police Stadium, Shahibaug,
Ahmedabad – 380 004, India.
E-mail: bhagya_mardi(at)yahoo.com
Received: 19.04.05
Accepted: 12.04.07