Cameroon - Confirmed case of poliovirus type 2 detected in an environmental sample in Mada, Far North region

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Outbreaks and Emergencies Bulletin, Week 22: 27 May - 02 June 2019

Circulating vaccine derived polio
virus outbreak Cameroon

1 Case (environmental sample)

EVENT DESCRIPTION

On 23 May 2019, the Global Polio Laboratory Network (GPLN) notified
WHO of a confirmed circulating vaccine-derived poliovirus type 2
(cVDPV2) in an environmental sample collected from Mada health
district in the Far North Province of Cameroon, at the border with Borno
State in Nigeria and Chad. The environmental sample was collected on
20 April 2019 from Mada Hospital surveillance sample collection site
and confirmed at the National Institute for Communicable Disease
(NICD) regional reference laboratory in South Africa. Genetic sequencing
showed that the strain is closely related to the cVDPV2 strain circulating
in neighbouring Nigeria, which originated in Jigawa State and spread to
other parts of the country, as well as to the Republic of Niger in 2018.
There have been no associated human cases of acute flaccid paralysis
(AFP) in Cameroon. However, the identification of the pathogen in the
environment is extremely significant as poliovirus spreads easily and
across large distances. Poliovirus is slated for global eradication.

Cameroon reported the last autochthonous polio case in 1999 while the
last imported case was reported in 2014, in the district of Kette located
in the eastern region of Cameroon. The case was confirmed in child who
developed acute flaccid paralysis in a refugee community. The province
shares borders with Chad and Borno State in Nigeria, the state which
reported the last wild polio virus (WPV) outbreak in the African region
in 2016.

Cameroon introduced the inactivated poliovirus vaccine (IPV) into the
national routine immunization schedule in 2015. However, the IPV1
national immunization coverage for 2018 has been suboptimal at 78%.
The coverage for oral polio vaccine 3 is also suboptimal at 78%.

PUBLIC HEALTH ACTIONS

The Ministry of Health and local health authorities in Cameroon,
with support from partners of the Global Polio Eradication Initiative
(GPEI), are conducting a detailed investigation, including assessing
the extent of circulation of this strain, identifying sub-national
immunity gaps and supporting efforts to strengthen sub-national
surveillance sensitivity.

SITUATION INTERPRETATION

The confirmation of poliovirus in an environmental sample in Cameroon highlights the
threat of spread of both wild and vaccine derived polio viruses in the African region,
especially as many countries are struggling to attain optimal immunization coverage. The
virus, which originated in Nigeria, has been detected in Chad, Niger and now Cameroon.
Accordingly, a sub-regional response focusing on the countries in the Lake Chad Region
has been adopted.

It is important that all countries, particularly those reporting frequent travel to polioaffected countries and areas, strengthen surveillance of AFP cases in order to rapidly detect imported cases and facilitate a rapid response. All countries should maintain a high routine immunization coverage at the district level to minimize the impact of any new virus introduction.

https://apps.who.int/iris/bitstream/handle/10665/325086/OEW22-270502062019.pdf

https://www.afro.who.int/publications/outbreaks-and-emergencies-bulletin-week-22-27-may-02-june-2019