Philippines: Re-emergence of vaccine preventable diseases (polio) - Operation Update Report - EPOA n° MDRPH032

Situation Report
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Description of the disaster

On 19 September 2019, the Department of Health (DOH) confirmed the re-emergence of polio (vaccine-derived poliovirus, VDPV) in the Philippines and declared a national polio outbreak. The re-emergence occurs almost 20 years after the Philippines was declared poliofree in 2000 and the last case of wild poliovirus was recorded in 1993.

Between 1 July and 3 December 2019, six human cases and 13 environmental samples were confirmed with cVDPV2, all genetically related. All human cases were reported from BARMM1, while environmental samples were found in Davao Region and National Capital Region (NCR). The environmental samples of 13 cVDPV1 found in Manila are genetically linked, while the first human case confirmed with VDPV1 from the island province of Basilan in BARMM was found not to be closely related to cVDPV1 detected in Manila, but with a possible genetic link possible that will be confirmed or not following evolutionary analysis pending.

According to the World Health Organization (WHO), VDPVs are rare strains of genetically mutated poliovirus derived from the strain contained in oral polio vaccines (OPV). VDPVs occur on rare occasions in areas with inadequate sanitation. In seriously under-immunized populations, an excreted vaccine virus can mutate and cause acute flaccid paralysis (AFP). VDPVs, therefore, pose a risk of reintroduction of poliovirus after polio eradication.

The resurgence of polio in the Philippines comes as the DOH and other partners continue to respond to dengue outbreaks and measles outbreaks. According to the latest reports, as of 29 November 2019, there had been 402,694 cases of dengue and 1,502 deaths, and 43,390 cases of measles and 573 deaths2. An increasing number of cases of diphtheria are also being reported, the DOH confirming 167 cases and 40 deaths in 2019 compared to 122 cases and 30 deaths in 2018.