People vaccinated against meningitis are supposed to have protection for three years but health officials have announced that meningitis epidemics have occurred in several areas where populations had recently been immunized.

“[Health researchers] are currently collecting information so as to identify the factors explaining the recurrence of the epidemic in districts where populations have been vaccinated”, Ousmane Badolo, head of the epidemiologic surveillance department at the ministry of health, told IRIN.

Vaccination campaigns target people between 2 to 30 years old; according to the ministry of health, 80 to 90 percent of the victims of meningitis belong to that age group.

A total of 714 people have died since 1 January out of 7,184 cases.

Several different bacteria can cause meningitis which is an inflammation of the protective membranes covering the central nervous system. The Neisseria sero-group is one of the most important to watch because it often leads to epidemics, experts say.

Badolo, the epidemiologist, said that health research teams from the UN World Health Organization and US-based Centers for Disease Control and Prevention have come to Burkina Faso to investigate. “This is the first time that such research is being conducted,” Badolo said, adding that at this stage he could only guess why the vaccination programmes have not worked.

“Perhaps it is because of population displacement,” he said, “for instance in gold mining areas people are often coming and going.”

The health researchers will focus their work on the districts of Réo in the central west of the country, Boulsa in the central north, Titao in the north and in Sig-nonghin a district in the north of the capital Ouagadougou.

The populations in each of those four districts were vaccinated last year yet each has reached epidemic thresholds.

A total of five out of the country’s 55 districts have reached the epidemic threshold and 14 others are on alert.

Meanwhile, 3.5 million people have been vaccinated this year out of a population of 14 million. The government said it is in the process of procuring a million more vaccines with the help of UN Children’s Agency UNICEF.