GOZ BEIDA, 30 October 2009 (IRIN) - A three-day nationwide polio vaccination campaign began on 30 October throughout Chad, including in the east where according to the World Health Organization the rate of routine immunizations is among the weakest nationwide.

On 27 October lab results confirmed six new polio cases, bringing the number of confirmed cases in Chad in 2009 to 30. Two regions are newly infected, Wadi Fira in the east and Batha in central Chad.

"Type 3 [poliovirus] has broken out in regions with poor routine vaccinations," Mohamed Mohammedi, WHO's polio technical expert covering eastern Chad, told IRIN. Fewer than half of the children living in the eastern districts of Wadi Fira, Ouaddai and Dar Sila have had routine polio immunizations, according to WHO's weekly polio bulletin as of 25 October.

There are three known strains of the polio virus. Type 3 is not as widespread but is as dangerous as type 1, Mohammedi said.

Vaccination campaigns in Chad have helped to wipe out type 1 cases nationwide, with 18 in 2007 to none thus far in 2009. But the number of type 3 cases has increased 10 times in that period.

The most affected areas are the capital N'djamena, which has half the cases, and Chari Baguirmi in southwestern Chad with eight.

Polio vaccinations are to continue till 1 November. The next round is scheduled to begin on 4 December.

Once established in the intestines, poliovirus can enter the bloodstream and invade the central nervous system – destroying nerves and leading to permanent paralysis in about one in 200 infections, according to the Global Polio Eradication Initiative. There is no known cure.

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