"More than 900 people are showing symptoms of chikungunya, which is transmitted by mosquito," Director-General of Health Alexis Elira Dokekias told a news conference on 14 June.
The disease's symptoms include muscle pain, headache, nausea, fatigue and rash, and are similar to those of dengue fever. There is no known cure; treatment consists of relieving the symptoms.
Dokekias said the first cases appeared in early June in the poor neighbourhoods of Bacongo and Makelekele in the south of Brazzaville.
Of 48 samples analysed in a laboratory in neighbouring Gabon, just over half tested positive for the virus, he said.
Dokekias urged anyone showing symptoms of the disease to report to the nearest medical centre, and called on all citizens to clean up potential mosquito habitats.
Chikungunya takes its name from a word in the Kimakonde language meaning "to become contorted" - a reference to the stooped appearance of those infected.
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