Authors: Dr Musole Chipoya, 1. Muzala Kapina (Zambia National Public Health Institute, Lusaka, Zambia; Zambia Ministry of Health) 2. Dien Francis Mwansa (Zambia Ministry of Health) 3. Albertina Ngomah (Zambia National Public Health Institute, Lusaka, Zambia; Zambia Ministry of Health) 4. Belem Matapo (World Health Organisation, Lusaka, Zambia) 5. Kennedy Matanda (Zambia Ministry of Health; Chienge District Health Office) 6. Lwara Kalembe Musa (Zambia Ministry of Health; Mansa District Health Office) 7. Mwaka Monze (Zambia Ministry of Health; Virology Laboratory University Teaching Hospital Zambia) 8. Keith Shaba (World Health Organization, Regional Office for Africa) 9. Mazyanga Liwewe (Zambia National Public Health Institute, Lusaka, Zambia; Zambia Ministry of Health) 10. Raymond Hamoonga (Zambia National Public Health Institute, Lusaka, Zambia; Zambia Ministry of Health) 11. Nicola Watt (Public Health England, Lusaka, Zambia) 12. David Simwaba (Zambia National Public Health Institute, Lusaka, Zambia; Zambia Ministry of Health) 13. Alexis Sciarratta (U.S. Centers for Disease Control and Prevention) 14. Kayeyi Nkomba (Population Council of Zambia, Zambia Ministry of Health) 15. Angela Gama (Zambia National Public Health Institute, Lusaka, Zambia; Zambia Field Epidemiology Training Program, Lusaka, Zambia; Zambia Ministry of Health) 16. LCDR Danielle Barradas (U.S. Public Health Service) 17. Jonas Hines (U.S. Public Health Service) 18. Nyambe Sinyange (Zambia National Public Health Institute, Lusaka, Zambia; Zambia Field Epidemiology Training Program, Lusaka, Zambia; Zambia Ministry of Health) 19. Victor Mukonka (Zambia National Public Health Institute, Lusaka, Zambia; Zambia Ministry of Health).
Citation Style For This Article: Chipoya M, Kapina M , Mwansa et al. Outbreak of Circulating Vaccine Derived Polio Virus Type-2 Chienge District, Luapula Province, Zambia, September 2019. The Health Press Zambia Bull. 2020; 4(4); pp 26
Background
Africa has seen a significant rise in circulating vaccine-derived polioviruses type 2 DPV2) outbreaks following the switch to bivalent oral polio vaccine (OPV) in 2016. In September 2019, the World Health Organisation (WHO) country office notified the Zambian Ministry of Health of a case of VDPV-2 in Chienge District, Luapula Province. This paper describes the investigation and public health response.
Methods
An Investigation was conducted per WHO standard operating procedures, where cVDPV is defined as VDPV demonstrating person-to-person transmission in the community or evidence from human and/or environmental detections of related viruses. The patient’s grandmother and mother were interviewed and blood samples were collected from the patient and 36 stool samples were collected from direct and community contacts aged <5 years from the two villages where the patient resided. Genetic sequencing for intrathymic differentiation was used to determine the relatedness of poliovirus samples.
Results
The patient was an unvaccinated two-year-old boy of Chienge District bordering the Democratic Republic of Congo (DRC); he had spent time in both countries, although his last trip to DRC was in >1 year ago. History indicated the patient developed sudden weakness in his lower limbs following a fever of <24hours in July. The sequencing results of the case showed VDPV2 with nine nucleotide differentiation from Sabin-2. Of the 36 stool samples, three isolated polioviruses (one Sabin-like-type 1 and two poliovirus-type 2[PV2]). The sequencing results of the two PV2 indicated genetic linkage to the index case but no established link to any ongoing cVDPV2 outbreaks in the DRC.
Conclusion
The confirmed presence of the cVDPV2 outbreak in Zambia represents another novel emergence of cVDPV2 since switching to bOPV. A mass vaccination campaign with monovalent OPV2 has been completed in Luapula Province following this outbreak. Furthermore, a catch-up vaccination was conducted in June 2020 countrywide to provide IPV coverage among children aged 3 to 59 months old children who missed type 2 containing polio vaccine from 2015 to March 2020.
Recommendations
Following this outbreak and the finding above we recommend strengthening AFP surveillance systems in rural-border towns with limited environmental surveillance, the establishment of more environmental surveillance sites within the country to investigate the presence of polioviruses in wastewater samples which would indicate the presence of polioviruses in those communities. Furthermore, we recommend improving vaccination coverage for both bivalent Oral Polio Vaccine (bOPV) and Inactivated Polio Vaccine (IPV) in all areas of the country to prevent further outbreaks of VDPV.