Indonesia recently confirmed its first case of polio in approximately 13 years, a concerning setback in global polio control. Additionally, WHO issued a statement this week discussing a polio outbreak in nearby Papua New Guinea. For decades, polio has been poised to join smallpox and become the second disease to be eradicated; however, despite substantial progress, challenges have persisted in achieving eradication. As previously reported by Outbreak Observatory, the occurrence of polio in multiple countries had prompted WHO this past November to extend the 2014 Public Health Emergency of International Concern for polio.
Indonesia has reported 2 genetically-linked isolates of circulating vaccine-derived poliovirus type 1 (cVDPV1) from Papua Province, with one of the isolates coming from a person diagnosed with acute flaccid paralysis and the other coming from a healthy community contact. The onset of paralysis in the patient occurred in November 2018; however, the confirmation of poliovirus infection was made more recently. Of particular concern is the finding that this outbreak may not be linked to the outbreak of cVDPV1 currently in neighboring Papua New Guinea.
According to WHO, polio eradication requires countries to establish high levels of population immunity through vaccination and to rapidly detect polio cases through the implementation of sensitive surveillance systems. The recent GPEI announcement regarding the diagnosed polio case in Indonesia emphasized the importance of maintaining this two-pronged approach to achieve this goal. Indonesia, along with all other countries in the WHO South East Asia region, was officially declared polio-free in 2014, and its last reported case was in 2006. According to joint WHO and UNICEF data released in July 2018, 3-dose polio vaccine coverage in Indonesia has remained at approximately 80% each year from 2014-2017. To promote polio vaccination, Indonesia has observed multiple National Polio Immunization weeks in the past. A 2016 article discussed how during one of these immunization weeks, the First Lady of Indonesia attended the launch event and more than 23 million children under 5 years of age were targeted for vaccination. Polio vaccination is provided free of charge as part of the country’s national immunization program, and receives financial support from Gavi. Despite these vaccination efforts, Indonesia may remain vulnerable to polio infection, especially in light of international travel. While the last indigenous case of wild poliovirus in Indonesia was reported in 1995, a successfully-controlled 2005-2006 outbreak of 305 cases caused by an imported case illustrates this risk. It is unclear whether the current cVDPV1 isolates are associated with travel or importation. In light of the recent developments in both Indonesia and Papua New Guinea, supplementary immunization activities (SIA) have been implemented in both countries.
WHO has provided guidance on surveillance to support polio eradication. WHO considers acute flaccid paralysis (AFP) surveillance to be the gold standard for polio surveillance. This surveillance method tests for poliovirus in stool samples from individuals exhibiting AFP. Additionally, according to WHO and other global health experts, environmental surveillance can be a useful supplement for AFP surveillance as it can detect circulating poliovirus in the absence of detected AFP cases. WHO has additionally provided guidance on enterovirus surveillance systems that may not exclusively focus on poliovirus but could support polio eradication efforts.
Over the years, Indonesia has implemented a number of initiatives to improve polio surveillance. Indonesia collaborated with WHO to advance its AFP surveillance in 1995. Environmental surveillance in Indonesia has been ongoing since it began at a site in Yogyakarta in 2004. The National Polio Laboratory located in Bandung, Indonesia collects sewage samples from selected surveillance sites. Environmental surveillance efforts have since expanded with support from the Regional Polio Laboratory Network of Indonesia.
The recent case of cVDPV1 in Indonesia demonstrates that even countries with relatively substantial vaccination coverage and ongoing surveillance can be vulnerable to the re-emergence of poliovirus. With a disease such as polio that can remain circulating in the environment and is highly transmissible, it is important to maintain vaccination and surveillance efforts, even in the absence of poliomyelitis cases.
Outbreak Observatory aims to collect information on challenges and solutions associated with outbreak response and share it broadly to allow others to learn from these experiences in order to improve global outbreak response capabilities.
Photo courtesy of CDC/Meredith Boyter Newlove, M.S.