How Nepal eradicated the smallpox virus

The fourth in a series about what it took for the scourge of smallpox to be finally eradicated from Nepal in 1975.

In 1966, the World Health Organization (WHO) launched a worldwide campaign to eradicate smallpox. The aim was ‘zeropox’ -- not just control of the disease, but its complete elimination.

After an aggressive campaign run by Nepal's autocratic government, the country saw its last case ever in 1975. The program should be celebrated. But what should also not be forgotten is that it sometimes resorted to heavy handed methods. Balancing public safety and individual rights was not easy.

Historically, smallpox had been one of the world's biggest and most terrifying killers. In South Asia, the disease attacked young adults and children, those born since the previous epidemic, leaving many disfigured or blind. In Nepal in the 19th  century, smallpox left few communities unscathed, and even killed a king.

In 1966, smallpox still plagued 31 countries, annually infecting 10-15 million people and killing 2 million. Two areas caused the most concern: the horn of Africa and South Asia, including Nepal.

Part I: Big story of smallpox in Nepal

Part II: The smallpox virus in British India

Part III: Smallpox, politics and power in Kathmandu

Part V: Viruses past, present and future

Smallpox vaccination statue outside the World Health Organization headquarter entrance in Geneva.

Nepal, a WHO official wrote in the early 1960s, ‘must be considered as one of the areas most highly endemic for smallpox in South East Asia’. In 1958, a wave of smallpox hit Kathmandu. A 1965 survey revealed that 16% of the Valley's total population had struggled with the virus at some point in their lives. Those were the ones the disease hadn't killed.

Each year a few imported cases appeared in the western hills. Don Messerschmidt describes a late 1963 outbreak along the hulakibato in Lamjung, but the main problem areas were the Kathmandu Valley and the Tarai, particularly the eastern plains because of heavy cross-border movement.

WHO and the Nepal government launched a pilot program in 1962 in Kathmandu Valley using new freeze dried vaccine, an improved version of the one Edward Jenner had devised in the 1790s, but got disappointing results.

After two and a half years, only 30% of Valley residents were protected. WHO blamed ‘administrative problems and the religious and mundane objections of some sections of the population to vaccination’.

In 1966, the program expanded countrywide, with new commitment and revised procedures, including better record keeping to prevent double counting. In 1971 the program started month-long mass vaccination campaigns. Each year for four straight years, several thousand temporary staff vaccinated 6 million Nepalis. Between 1967 and 1975, 39 million Nepalis got vaccinated or re-vaccinated.

Another new strategy proved a game changer: aggressive surveillance and containment. Previously, officials had prioritised vaccinations. They had not traced and mapped infections, and thus did not know how many people had the virus and where. In 1971, a WHO official later wrote, ‘vigorous surveillance became the rule’.

Surveillance meant routine house-to-house searches. Instead of waiting for cases to be reported, program workers went looking for them. Containment meant vaccinating and revaccinating the entire population near a newly discovered case. This was erring on the safe side by casting a broad net. The program also intensified tracing, detecting infection origins in a remarkable 95% of cases.

The aggressive surveillance and containment methods delivered results. ‘It appeared that transmission had been interrupted,’ a WHO official noted later. Nepal had devised ‘a new and surprisingly effective tactic’.

But then came a setback: ‘a tidal wave’ of new cases with nearly 2,000 new infections in 240 separate outbreaks. Three of every four of these cases were imports from Uttar Pradesh and Bihar in India where smallpox proved particularly recalcitrant. Of Nepal's 12 million population at the time, 90% lived within 100km of these Indian states.

The program responded with more vaccination campaigns, surveillance, and containment, making steady progress. To address outbreaks in Morang the Nepal smallpox program in 1975 initiated a ‘watchdog’ system, a tactic recently devised in India. Staff were posted at the houses of infected people to ensure that they did not leave and that no unvaccinated person entered. Cash rewards were given to citizens and staff reporting new cases.

In April 1975, Nepal saw its last case. A disease that had plagued Nepalis for centuries was gone. Looking back, WHO officials saw the surveillance and containment program as the key.

‘The shift in strategy in 1971, laying great emphasis on surveillance-containment, was largely responsible for the success of the Smallpox Eradication Programme in Nepal,’ wrote the program's director in a 1977 wrap up report. ‘It is possible that transmission would have been interrupted earlier if the watchguard system had been adopted during 1974.’

In many ways Nepal's eradication of smallpox was a heroic victory. The global smallpox program's director applauded Nepal's ‘remarkable accomplishments’. This narrative is not inaccurate but it is not the whole story.

To begin with, smallpox eradication owed a great deal to biology. Compared to other diseases, smallpox was simply easier to eradicate. It was easy to see and diagnose (no asymptomatic infections) and did not re-infect people once gone. The disease's painful symptoms prevented movement, slowing transmission. Moreover, the vaccine was easy to administer and extremely effective. There was no virus reservoir among animals re-injecting the disease into human society again and again.

Diseases like malaria and polio had far more natural advantages, and have proven much harder to eradicate globally.

‘Without the particular characteristics of smallpox and the smallpox vaccine,’ historian Randall Packard has observed, ‘the disease would have been much more difficult to conquer, and the campaign would, in all likelihood, have failed. As it was, it only succeeded by the thinnest of margins.’

One particular challenge was how to handle Nepalis who resisted vaccination. In the eastern Tarai, many people, particularly indigenous groups, held what a WHO report described as 'religious objections to vaccination’.

WHO said this area became 'the scene of many problems of containment’. In Kathmandu, some Newar groups used to 'strongly object' to vaccination. In Kailali, some Tharus 'resisted vaccination for religious reasons'.

Historian Susan Heydon notes that program workers often unjustifiably dismissed the concerns of Nepalis who resisted vaccination. Those who hesitated, she notes, were blamed as superstitious, derided as ‘backward and uneducated’.

Instead, she faults the WHO program itself for not doing enough to educate the general population about the benefits of vaccination. She also notes that the program often administered vaccinations during hours next to impossible for ordinary working people.

Eradication program workers also occasionally used unnecessary coercion. Coerced vaccinations were not common worldwide or in South Asia. But as historian Packard notes, there was a ‘tendency for aid workers to view themselves as somehow empowered to do whatever it takes to fulfill their mission, and to disregard local customs and laws’.


In India and Bangladesh, historian Paul Greenough discovered that 'heavy-handed methods were sometimes relied upon'. On one occasion in Bihar in 1975, for example, health officials accompanied by police arrived at a tribal person's house by jeep at midnight, broke down the door, held down family members, and forcibly vaccinated them. Mandatory vaccinations and re-vaccinations as part of broad containment efforts sometimes sparked 'chaos' in villages.

'Encounters with government vaccinators,' Greenough observes, were 'never about immunisation alone.' Religious, caste, and gender dynamics shaped interactions, as did ill will from previous health campaigns.

One American health worker in India later recalled how a sense of unbridled self-righteousness led him to mistreat people. 'One of the rules was that everybody gets vaccinated. I was awful in my conviction of purity of purpose -- in breaking down doors and vaccinating crying women, etc.' To a large degree, the ends seemed to justify the means.

Official reports, Greenough writes, often dismissed resistance and underreported coercion. He wishes there had been much more training for healthworkers and broader,more careful education for the public.

In Nepal, one foreign smallpox fieldworker described how health workers sometimes had to search for Nepalis hiding from them in fear:

‘... a good natured room to room search of houses with flashlights, accompanied by the village leader, would detect adults and children hiding under beds, in chests, large wicker baskets, and even in large clay storage vessels. However, the search was done as a game of hide and seek, with laughter after people were found and vaccinated, such as in one particular case where lifting the cover of a large wicker basket revealed two children hiding inside.’

This may have been seemed like a game to health workers, but probably not to those Nepali men, women, and children with unknown government strangers searching for them. They seemed terrified.

In the name of containing smallpox, a global health problem and an old scourge in Nepal, in the late 1960s and 1970s Nepal's government had tremendous authority to monitor and search Nepal's population. Maintaining public safety certainly justifies strong action, but the unnecessary infringement of individual rights and liberties must also be avoided as well.  

This is the third in a series of articles about the history of disease in Nepal. The fifth installment will look at what Nepal can learn from past epidemics in dealing with this one.  Tom Robertson, PhD, is researching the environmental history of Kathmandu Valley.

Tom Robertson


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