Plague bacteria

A digitally-colourized scanning electron micrograph of a number of yellow-coloured Yersinia pestis bacteria that had gathered on the purple spines of a flea. Human plague infections continue to occur in the western United States, but significantly more cases occur in parts of Africa and Asia, the U.S. Centers for Disease Control says. (U.S. National Institute of Allergy and Infectious Diseases)

A plague outbreak in Madagascar has infected 119 people, including 40 deaths, the World Health Organization said Friday in warning about the risk of spread in the densely populated capital.

In the capital of Antananarivo, there's been two cases and one death from the bacterial illness that is mainly spread between rodents by fleas. 

"There is now a risk of a rapid spread of the disease due to the city's high population density and the weakness of the healthcare system," WHO said. 

The UN health agency noted that a high levels of resistance to an insecticide used to control fleas complicates the outbreak.

Only 2 per cent of reported cases are the pneumonic form. Doctors say pneumonic plague kills faster than the bubonic form. As the name implies, pneumonia can result, which spreads from person to person by coughing.

Humans bitten by an infected flea usually develop a bubonic form of plague. It results in swelling of the lymph nodes, WHO said. If diagnosed early, bubonic plague can be successfully treated with antibiotics.

The first known case of the plague was a man from Soamahatamana village in the district of Tsiroanomandidy, identified on Aug. 31. He died on Sept. 3 and authorities notified the WHO of the outbreak on Nov. 4, the agency said.
 
No trade or travel restrictions are recommended, WHO said. It did suggest surveillance in urban areas such as the capital.

Plague has been around for millennia and human cases occur worldwide every year. In Madagascar, there's been more than 200 cases reported every year since 1990, according to the U.S. Centers for Disease Control and Prevention.

In the U.S. southwest for example, the CDC says plague bacteria circulate at low rates within some rodent populations. Occasionally, other species such as humans become infected.

With files from Reuters