Health authorities in Burundi recently said that they had detected eight samples of polio, officially declaring the landlocked African nation’s first outbreak in more than 30 years.
- Heath authorities said there was a confirmed case in an unvaccinated four-year-old child in Isale district, in western Burundi, as well as two other children with whom he had been in contact.
About Polio
- Polio is highly infectious and timely action is critical in protecting children through effective vaccination.
- The disease is transmitted through contaminated water and food, or by contact with an infected person, many do not become seriously ill, but some can go on to develop acute flaccid paralysis.
- Its early detection is critical in containing a potential outbreak.
- 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.
- Circulating poliovirus type 2 is the most prevalent form of polio in Africa and outbreaks of this type of poliovirus are the highest reported in the region, with more than 400 cases reported in 14 countries in 2022.
- Type 2 infection can occur when the weakened strain of the virus contained in the oral polio vaccine, circulates among under-immunized populations for long periods.
- 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.
- The oral poliovirus vaccine (OPV) is used in many countries to protect against polio disease. Oral poliovirus vaccine contains attenuated or weakened version of either one (monovalent OPV), two (bivalent OPV), or all three (trivalent OPV) poliovirus types. After wild poliovirus type 2 was declared eradicated in 2015, the world switched from trivalent OPV to bivalent OPV. Bivalent OPV contains poliovirus type 1 and 3. This switch means that the bOPV used globally no longer protects against WPV2.
- Countries that use bOPV for routine immunization have added a single dose of IPV to protect against WPV2.
- In rare instances, the vaccine-virus may be able to circulate over time and mutate in communities with insufficient immunity or immunocompromised individuals. These mutated OPV strains can cause polio disease. They are called vaccine-derived polioviruses (VDPVs).
- IPV protects people against all three types of poliovirus. IPV does not contain live virus and cannot cause disease. It protects people from polio disease but does not stop transmission of the virus.
- OPV can be used to contain a polio outbreak. Use of all OPV will stop when polio is eradicated globally. This will prevent re-establishment of transmission from VDPVs.
