Immunization

Vigilance is key to keeping polio out of Nepal

Sensitive surveillance and strong routine immunization have kept Nepal polio-free

High up in the Nepalese district of Humla, where most villages lie at between 3 000 and 5 000 metres above sea level, the highest district in Nepal, a female community health volunteer visits five-year-old Kiran* at his home. Kiran is complaining that he is unable to move his legs and is starting to become paralysed in his arms as well.

Children line up for polio vaccination at a school in Nepal
Children line up for polio vaccination at a school in Nepal
WHO

Muscle weakness or paralysis could be due to a number of different viral or bacterial infections or other causes. In Nepal, community health volunteers are trained to be on high alert for these symptoms. This is because acute flaccid paralysis is a sign that Kiran might have poliomyelitis.

Nepal saw its last case of polio caused by indigenous wild poliovirus in 2000. Since then, however, the country’s long and much-travelled border with India, combined with low immunity in Nepal in earlier days, saw it repeatedly infected by wild poliovirus of Indian origin. Quick detection of polio has allowed Nepal to rapidly respond to such importations, and boosting its routine immunization system has protected it from outbreaks resulting from these importations.

Immediate action: reporting, testing, surveillance

“A single confirmed case of this highly infectious disease is cause for extreme concern,” says Dr Rajendra Bohara, from the WHO’s office in Nepal. “Female community volunteers are the pillar to detect and report any case of acute flaccid paralysis, even from the most remote villages. Every time there is a suspected case of polio, we take urgent action.”

The health volunteer immediately reports the suspected case to the district health officer and organises for Kiran to travel to Humla District Hospital, a formidable challenge in this remote mountainous district where it can take 10 days to walk to the nearest road.

At the hospital, Kiran is thoroughly examined and two stool samples are taken 24 hours apart. As the highest concentrations of poliovirus are found within two weeks of the first paralysis symptoms, speed is crucial. The samples are stored immediately in a refrigerator and transported in ice packs to the WHO office in Kathmandu. From there, they are sent to the WHO-accredited polio testing laboratory in Bangkok, Thailand.

A typical village in Humla.
A typical village in Humla.

While waiting for the laboratory results, one of WHO Nepal’s 15 surveillance medical officers travels to Humla District Hospital to conduct a thorough investigation. The health staff search for other children with the same symptoms as Kiran and check the coverage of routine polio vaccination. Preparations also begin for a vaccination campaign of the surrounding community and districts to ensure that, if it turns out that Kiran has polio, the disease is stopped in its tracks.

Last year (2013) almost 600 cases of acute flaccid paralysis were reported in Nepal but fortunately not one of these children, including Kiran, were found to have polio. Previously the country had experienced polio reintroductions caused by virus of Indian origin which were quickly controlled. Even while the South-East Asia Region prepares to be certified polio-free, the guards need to be kept up as long as there is still polio in other parts of the world. “This is a critical period, we must remain vigilant,” says Dr Shyam Raj Upreti, manager of the Expanded Programme on Immunization in Nepal.

The immunity shield

Routine immunization is the number one method of minimising the impact of the re-introduction of polio in Nepal. More than 90% of Nepalese children now receive DPT (diphtheria, pertussis, tetanus) and polio vaccine through the routine immunization programme. However this ‘immunity shield’ is not uniform throughout the country.

Nepal’s rigorous polio surveillance system is key to identifying which communities are at risk and where vaccination campaigns and or strengthening of routine immunization are most needed. Until polio is eradicated worldwide, there is always the threat that the virus could be imported.

Regional interaction

Polio vaccination reaches some of the most remote parts of Nepal
Polio vaccination reaches some of the most remote parts of Nepal
Tinje VDC, Dolpa

“When polio still existed in India, we struggled to prevent the disease travelling across the border,” says Dr Upreti. “Thousands of people cross that border every day.”

India is now polio free. But every year, national polio immunization days are held to boost immunity among children in both India and Nepal. In particular, mobile vaccination booths are sent to remote rural communities and set up at cross-border entries.

“We have developed very good working relations with our Indian counterparts, meeting with them regularly. Whenever there is a case of acute flaccid paralysis reported in Nepal, we immediately report it to the Indian authorities and vice versa,” says Dr Bohara. “Neighbouring countries must work together to ensure that we all maintain the highest possible vigilance against this crippling disease.”

*not his real name

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