Emergencies preparedness, response

Poliomyelitis in Chad

29 October 2003

Disease Outbreak Reported

Two cases of paralytic poliomyelitis due to type 1 poliovirus, with onset of paralysis on August 2 and 27, 2003 have been confirmed in the Mayo-Kebbi and Logone Orientale provinces of southern Chad, near the Nigerian, Cameroon and Central African Republic borders.

Chad has not reported polio cases since June 2000. The viruses detected in Chad are genetically close to viruses circulating in north-eastern Nigeria in 2002 and 2003. The cases in Chad follow the reporting of paralytic polio due to type 1 poliovirus from Burkina Faso, Togo and Ghana earlier this year. Viruses found in these three countries, which also had not reported wild poliovirus for more than two years, are genetically related to type 1 virus circulating in northern Nigeria and southern Niger in 2002 and 2003.

Nigeria is one of the three remaining poliovirus reservoirs in the world and poses a high risk of re-infecting polio-free areas in the entire west and central Africa.

WHO is currently working with Ministries of Health in Chad and Cameroun to plan for synchronized sub-national immunization campaigns targeting children aged under 5 years with Oral Polio Vaccine starting 11 November. It is critical that every child is reached during these activities to ensure that population immunity is high enough to prevent spread of imported virus and protect against further importations.