Abidjan — Ivorian health officials are vaccinating people against yellow fever in Abidjan, the commercial capital, and two other major cities, after the disease killed two people and struck nine others in recent weeks.

During the same period, dengue fever - for which there is no vaccine - killed one person, and there have been 10 more confirmed cases, according to the Ministry of Public Health and Hygiene.

Yellow fever and dengue fever, both viral illnesses transmitted by the Aedes mosquito, have struck communities in Abidjan, Grand Bassam and Bouaké, said Health Minister Eugène Aouélé Aka.

"We are working to eliminate mosquitoes in the affected zones," he told reporters on 29 July. "We must contain the problem as quickly as possible - we're in the rainy season when these diseases spread rapidly."

The illnesses commonly occur during the rainy season, when mosquitoes multiply, but poor hygiene is the culprit, an infectious disease expert in Abidjan told IRIN.

"If we are seeing these epidemics, it is because people are not practicing proper hygiene," said Attoh Touré of the National Public Hygiene Institute. He said health authorities have not made prevention campaigns a priority.

There is no cure for yellow fever and vaccination is the single most important prevention measure, according to the World Health Organization (WHO). The disease kills about 50 percent of those who fall ill, mostly due to lack of treatment for associated fever and dehydration, WHO says.

WHO notes that dengue fever can result in a potentially lethal complication called dengue haemorrhagic fever, and that the number of cases has risen dramatically in recent decades; as of March 2009 some 2.5 billion people - two-fifths of the world's population - were at risk.