The World Health Organization estimates that over 100 million Hepatitis A infections occur each year, causing approximately 1.5 million clinical cases.
Published Oct 05, 2025 | 7:00 AM ⚊ Updated Oct 05, 2025 | 7:00 AM
The first cases appeared quietly in late 2022. A few children developed fever, diarrhoea, and yellowing of the eyes. The symptoms looked like jaundice, a condition many families believed would heal by itself.
Synopsis: A study has found that 92 percent of the households at Kariyammana Agrahara lacked drainage systems. Wastewater accumulated around shanties where children played. Water supply was irregular, and residents stored water, bought from tankers or nearby RO plants, in drums. Only 8 percent of households boiled water before consuming. The residents washed their utensils in stagnant water.
The illegal slum at Kariyammana Agrahara near Kadubeesanahalli in Bengaluru often made headlines for different reasons. Parts of the slum were razed, but many people, mostly migrant labourers, still live under tin roofs in unhygienic conditions.
What has not been reported is an invisible enemy in the slum. It thrives in poor living conditions, where humans are forced to lead an undignified life.
A study has found that 92 percent of the households lacked drainage systems. Wastewater accumulated around shanties where children played. Water supply was irregular, and residents stored water, bought from tankers or nearby RO plants, in drums. Only 8 percent of households boiled water before consuming. The residents washed their utensils in stagnant water.
The invisible enemy quietly reared its ugly head between September 2022 and June 2023, justifying the fears of public health experts. As many as 25 children, aged 3 to 16, contracted Hepatitis A in an outbreak that lasted ten months.
The study published in the International Journal of Medicine and Public Health pointed out that the outbreak was due to reasons like inadequate sanitation and hygiene.
“Apart from being an unauthorised slum, several deficiencies exist in their lives. The lack of entitlements is the foremost, and they have drawbacks, like the poor quality of their dwellings and infrastructure deficits such as electricity, piped water supply, sanitation, drainage system, and many practice indiscriminate waste disposal,” the authors documented.
The slum housed 3,840 households and nearly 9,000 residents, all migrants who had moved to Bengaluru searching for employment. They worked as waste pickers, rag sorters, security guards, household help, and janitors in nearby offices.
The researchers identified that 54.9 percent of households practiced poor food hygiene. Families left cooked food uncovered, exposing it to flies and dust. The stagnant water in washing tubs harboured bacteria and viruses that moved from one utensil to the next.
Hand hygiene practices remained inconsistent. Only 48 percent of families washed their hands properly, even though Hepatitis A transmits through the faeco-oral route—from contaminated food, water, or close contact with infected persons.
“Hepatitis A is a vaccine-preventable disease and is transmitted through the faeco-oral route and close contact with infected persons. Open-air defaecation and lack of toilets are a public health problem in these slums existing in a hustling city,” the authors noted.
The toilet crisis compounded every other sanitation failure. With 12.9 percent of households having no toilet facilities at all, and 32 percent practicing open defecation, human waste contaminated the environment where families lived, children played, and water was collected.
The absence of municipal services created this cascade of failures. As an unauthorised slum, residents received no entitlements—no piped water supply, no sewage system, no waste collection. The infrastructure that prevented disease in formal settlements did not exist.
“The residents in a slum area of Bengaluru city consisted of migrants who moved into the area in search of employment, lived with their families. They are short of sanitation and provision of clean water along with other necessities,” the authors noted.
The study found that 52 percent of the infected children had not received vaccination, despite the availability of a vaccine that prevents Hepatitis A. Many had missed routine health checks that track immunisation status.
School attendance data revealed another gap in protection. Among affected children, 44 percent did not attend school, cutting them off from health education programmes that teach basic hygiene practices.
“Among these cases, 13 (52%) were not immunised according to their age, and 11 (44%) of these children were not attending school,” the authors reported.
The combination proved potent. Children without vaccination moved through an environment saturated with contamination. They drank water without boiling, ate food prepared in unhygienic conditions, and lived where human waste mixed with their surroundings.
The first cases appeared quietly in late 2022. A few children developed fever, diarrhoea, and yellowing of the eyes. The symptoms looked like jaundice, a condition many families believed would heal by itself.
Health workers screened 143 children as the situation escalated. Out of 25 symptomatic cases, six received laboratory confirmation for Hepatitis A. Two children required hospital admission. No deaths occurred, but cases peaked dramatically in March 2023, with 32 percent of all infections occurring that month.
“The peak in cases during March 2023 likely reflects the culmination of risk factors, sanitation and hygiene deficits, overcrowding, and gaps in the infrastructure with limited case detection,” the authors explained.
The epidemic curve showed a sharp rise to a peak, then a decline. The pattern suggested a point source outbreak—a single exposure or cluster of exposures triggering multiple cases. However, the extended timeline indicated continuous person-to-person transmission rather than one contamination event.
“The prolonged outbreak timeline and peak pattern reflect the intersection of viral persistence in a poor environment and human behavioural factors sustaining transmission,” the researchers found.
The documented cases represented only a fraction of actual infections. Hepatitis A often produces no symptoms in children, allowing them to carry and spread the virus without anyone knowing.
“High subclinical burden was evident as only six laboratory confirmed cases were documented and modelling suggests asymptomatic carriers fuelled transmission,” the authors stated.
This silent transmission prolonged the outbreak and complicated control efforts. Children who felt fine continued their normal activities, spreading the virus through contact with others, through shared food, and through contaminated surfaces.
The floating nature of the migrant population added another layer of difficulty. Families moved in and out of the slum, some leaving before health workers could screen them, others arriving and introducing new susceptible individuals into the community.
“Being an unauthorised slum and these migrants being a floating crowd, made this population dynamic and hence tracking cases was difficult,” the researchers noted.
Under-reporting remained constant throughout the ten months. Many families chose not to seek medical intervention, believing the illness would subside on its own. The true number of infections likely exceeded what health workers documented.
When health workers detected the outbreak, they formed an investigation team that included staff nurses, field staff, and 10 trained Community Health Associates from the same area. A private agency had established a primary health centre to serve the population, and this centre became the base for intervention efforts.
The team conducted house-to-house visits to identify symptomatic cases and their contacts. They used validated questionnaires to collect demographic information and epidemiological case sheets to capture details about onset dates, symptoms, water sources, and hygienic practices.
“These activities were carried out by trained Community Health Associates (CHAs) and health care workers to provide primary health care,” the authors noted.
Health education formed the core of the intervention strategy. Teams visited different communities and taught families about hand hygiene and food hygiene. They stressed the importance of boiling water and covering cooked food.
Workers monitored all children in the area regularly through active surveillance. They followed infected children until their bilirubin levels returned to the normal range. Community surveillance continued until transmission stopped.
Local authorities worked with the landowner to maintain cleanliness drives. The coordinated effort gradually brought the outbreak under control.
“The observed decline in cases post-peak suggests that coordinated public health intervention of giving health education, community surveillance, and environmental sanitation drives was effective in curbing transmission,” the authors concluded.
The Bengaluru outbreak mirrored similar incidents in other urban slums. In Vellore and western India, hepatitis outbreaks among children are connected directly to contaminated water supplies and poor sanitation.
The World Health Organization estimates that over 100 million Hepatitis A infections occur each year, causing approximately 1.5 million clinical cases. The disease remains less common in developed countries because sanitation and vaccination coverage function effectively.
“According to WHO, the spread of Hepatitis A Virus (HAV) cases in developing countries is higher than that of developed countries is due to poor sanitation and below-average living conditions in slum areas,” the authors stated.
The researchers emphasised that Hepatitis A continues to prevail in hyper-endemic regions, requiring targeted strategies for elimination. They called for sanitation infrastructure upgrades combined with comprehensive surveillance and vaccination programmes.
“This calls for a vaccination drive targeting the children from this community, along with marked improvement in sanitation,” the study recommended.
The authors stressed that while vaccination or sanitation individually contribute to lowering infection rates, the most substantial impact comes from implementing both strategies together.
“Though either vaccination or sanitation individually contributes to lowering the rates of infection, the most substantial impact is achieved when they are implemented together, reinforcing the value of integrated public health interventions,” they concluded.
(Edited by Majnu Babu).
