An outbreak of plague has killed 47 people in Madagascar and reached the island's densely populated capital, raising fears of a "rapid spread".
Cases have been reported in seven regions, with two cases in the capital of Antananarivo, the largest city in Madagascar with a population of approximately 1.4 million.
The disease, which is similar to the Black Death that swept medieval Europe, is endemic in parts of Madagascar. But the World Health Organisation (WHO) says there is a "risk of rapid spread" now that it has reached Antananarivo, due to the city's high population density and the weakness of its healthcare system.
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Health workers have mounted a pest control campaign through slum areas around the city, but WHO says the situation has been further complicated by a high level of resistance to deltamethrin, an insecticide used to control fleas.
The bacterial disease is caused by Yersinia pestis, which is spread by fleas and mostly affects rats. Humans bitten by an infected flea usually develop a bubonic form of plague, which causes a swelling of the lymph node and can prove fatal. Other symptoms can include chills, fever, muscle pain and seizures. If detected early enough, it can be treated successfully with antibiotics.
If the bacteria reach the lungs, it can then develop into pneumonic plague, which can be spread to other humans by coughing and can kill within 24 hours. Health officials says only two per cent of the cases in Madagascar were of this type.
Untreated bubonic plague can also develop into septicemic plague, where skin and other tissues can turn black and die, especially on fingers, toes and the nose.
The first case of the latest outbreak in Madagascar is believed to be a man from Soamahatamana village in the district of Tsiroanomandidy, around 130 miles from the capital. He was identified on 31 August and died three days later.
In Africa, plague is consistently reported from the Democratic Republic of the Congo, Madagascar and Tanzania. Although rare in the United States, it has been known to occur in parts of California, Arizona, Colorado and New Mexico. No British cases have been reported since 1918, says the National Travel Health Network and Centre.
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