Plague Outbreak in Madagascar

A total of 40 deaths have been recorded in the latest outbreak of bubonic and pneumonic plague in Madagascar.

While most of the world’s attention has been focused on the current Ebola outbreak in West Africa, public health officials are faced with another remerging infectious disease.

According to a November 21, 2014 report issued by the World Health Organization (WHO), Madagascar is in the midst of an outbreak of the plague.

Plague, or Yersinia pestis, is a disease of rodents that spreads through fleas. Bubonic plague, known historically as the black death, may lead to swelling and necrosis lymph nodes, whereas pneumonic plague affects the lungs.

Humans may contract plague through fleas or through contact with droplets from a person with the pneumonic form of the illness. Because plague is a bacterial illness, it can be treated with antibiotics, but antibiotics are most effective if a diagnosis of plague is established early. Often, patients with pneumonic plague do not benefit from antibiotic treatment because the time between the first symptoms and death is typically fewer than 24 hours.

The Madagascar Ministry of Health reports that the first case was a young man from Soamahatamana village, whose symptoms were first identified as plague on August 31, 2013. Since then, the young man has died, and 119 more cases have been confirmed as of November 16, 2014.

The outbreak has caused 47 fatalities as of November 25, 2014. The vast majority (98%) of cases identified to date are of the bubonic form of plague and the remaining 2% are pneumonic.

To date, officials have identified 2 total cases of plague in Madagascar's capital city, Antananarivo. WHO officials worry that the high population density and insufficient medical infrastructure of Antananarivo may hasten the spread of the plague.

Precautionary measures, such as spraying insecticides to reduce populations of fleas, may help control the spread of plague in Madagascar. The effectiveness of pesticides, however, is limited due to the high prevalence of insecticide-resistant fleas on the island.

Plague first arrived in Madagascar in 1898, but was nearly eliminated by the 1930s through widespread use of antibiotics. Unfortunately, by the late 1990s officials noted a resurgence of cases. Approximately 200 cases of plague are recorded annually, which accounts for nearly half of the recorded cases of the plague on the African continent between 1982 and 1996. In 1995, a multidrug-resistant form of plague was identified.

Strains previously identified in Madagascar have shown evidence of resistance to several antibiotics commonly used in the treatment of plague, including ampicillin, chloramphenicol, kanamycin, streptomycin, spectinomycin, sulfonamides, tetracycline, and minocycline. Scientists were able to identify resistance factors in the bacteria, such as beta-lactamase, and other enzymes that break down specific active structures in antibiotics, including the active moiety in aminoglycoside antibiotics.

Also concerning was the finding that plasmids carrying resistance factors spread to Yersinia pestis bacteria in the gastrointestinal tract of fleas. This finding suggests that resistance factors can spread in the natural environment—not just in humans.

Several organizations are actively working to contain the epidemic, including the WHO, the Pasteur Institute of Madagascar, the Red Cross, and the African Development Bank.

References:

• World Health Organization. Plague — Madagascar. http://www.who.int/csr/don/21-november-2014-plague/en/. Accessed November 2014.
• Chanteau S, Ratsifasoamanana L, Rasoamanana B, et al. Plague, a reemerging disease in Madagascar. Emerg Infect Dis. 1998;4(1):101-104.
• Galimand M, Guiyoule A, Gerbaud G, et al. Multidrug resistance in Yersinia pestis mediated by a transferable plasmid. N Engl J Med. 1997;337(10):677-680.