TAG: GS 3: SCIENCE AND TECHNOLOGY
THE CONTEXT: The resurgence of wild-type poliovirus type-1 (WPV1) in Pakistan and Afghanistan poses a significant threat to the ambitious goal of eradicating the virus by 2026.
EXPLANATION:
- Despite initial progress, recent trends indicate a troubling increase in cases and environmental circulation of WPV1, raising alarms about the potential for international spread and the effectiveness of current vaccination campaigns.
- In 2023, Afghanistan and Pakistan each reported six cases of WPV1, a decrease from the previous year’s 22 cases in total (two in Afghanistan and 20 in Pakistan).
- However, this apparent reduction is overshadowed by an uptick in 2024, with six cases in Afghanistan and five in Pakistan already reported.
- This trend suggests that the total number of cases for the year may match or exceed those of 2022.
- A more concerning indicator is the rising number of positive environmental samples.
- In 2022, 125 positive samples were collected from 28 districts in Pakistan, with 119 belonging to a genetic cluster indicative of importation from Afghanistan.
- By June 1, 2024, Pakistan had already recorded 153 positive samples from 39 districts.
- Afghanistan also reported 34 positive samples as of April 8, 2024. These samples were collected from historically critical areas such as Karachi, Quetta, Peshawar-Khyber blocks in Pakistan, and Kandahar in Afghanistan.
Implications of Environmental Findings
- The presence of positive environmental samples in epidemiologically critical areas signals a significant risk to past gains in polio eradication.
- These regions, known for being historical reservoirs of the virus, reflect the inadequacy of current vaccination campaigns.
- Despite high immunization rates in Pakistani cities, the virus still threatens unvaccinated or under-vaccinated children, with Karachi city reporting two of the six cases in 2023.
- The rising positive environmental samples highlight issues with vaccination campaigns, such as fake finger markings without actual vaccinations.
- This persistent problem undermines the efforts to achieve comprehensive immunization coverage, leaving gaps that the virus can exploit.
Cross-Border Spread Risks
- The geopolitical dynamics between Pakistan and Afghanistan exacerbate the risk of WPV1 spread.
- With over 0.5 million Afghan refugees forced to leave Pakistan and an estimated 0.8 million more to be evicted soon, there is an increased risk of cross-border transmission.
- Many returning refugees are unvaccinated or under-immunized, particularly in southern Afghanistan, heightening the threat of the virus spreading further.
- The spread of WPV1 from Afghanistan to Pakistan has already been observed, with the virus predominantly circulating in Afghanistan in 2022 and being detected in Pakistan in 2023 and 2024.
- This cross-border movement underscores the need for coordinated international efforts to control and eradicate the virus.
International Response and Future Challenges
- The World Health Organization (WHO) emphasizes the critical need for sustained and enhanced polio vaccination campaigns.
- The presence of WPV1 in key areas of Pakistan and Afghanistan jeopardizes global health security and requires a robust international response to prevent further spread.
- Achieving the goal of eradicating WPV1 by 2026 now faces significant hurdles.
- Ensuring comprehensive vaccination coverage, addressing fake vaccination practices, and managing the movement of large refugee populations are essential steps in combating the resurgence of WPV1.
Poliomyelitis:
- Polio, or poliomyelitis, is a crippling and potentially deadly infectious disease.
- Poliovirus is transmitted from one person to another by oral contact with secretions or faecal material from an infected person.
- Once viral reproduction is established in the mucosal surfaces of the nasopharynx, poliovirus can multiply in specialized cells in the intestines and enter the blood stream to invade the central nervous system, where it spreads along nerve fibres.
- When it multiplies in the nervous system, the virus can destroy nerve cells (motor neurons) which activate skeletal muscles.
- There are three types of wild poliovirus (WPV): type 1, type 2, and type 3.
- People must protect themselves against all three types of the virus to prevent polio disease. Polio vaccination is the best protection.
- Type 2 wild poliovirus was declared eradicated in September 2015.
- The last detection was in India, 1999. Type 3 wild poliovirus was declared eradicated in October 2019. It was last detected in November 2012.
- Only type 1 wild poliovirus remains.
- There are two vaccines used to protect against polio disease: oral polio vaccine and inactivated poliovirus vaccine.
