Emergencies preparedness, response

Plague

Madagascar plague: preventing regional spread

Two women and two men discussing, at a port in Seychelles
WHO/E. Musa

2 November 2017 - More than 1800 suspected, probable, or confirmed plague cases were reported in Madagascar from August to late October 2017, resulting in 127 deaths. WHO has moved quickly in response to this unusually severe outbreak by supporting the Government of Madagascar, while at the same time working with nearby countries and territories to prevent regional spread.

Suspected cases from Seychelles test negative for plague

18 October 2017 - Samples from patients in Seychelles suspected to be ill with pneumonic plague tested negative at a WHO partner laboratory in Paris, France on Tuesday, 17 October 2017.

WHO is working with the Seychelles health authorities to reduce the risk of plague spreading from neighbouring Madagascar, which faces an unprecedented outbreak that has killed more than 70 people since August. No plague cases have been confirmed in the Seychelles.

Everything you need to know about plague

WHO

How can I protect myself from being infected with plague? What should I do if I suspect I have plague? How can plague be treated?

Read this story to find out answers to these and many other frequently asked questions related to plague.

WHO scales up response to plague in Madagascar

6 October 2017 – WHO has delivered nearly 1.2 million doses of antibiotics and released US$1.5 million dollars in emergency funds to fight plague in Madagascar. The outbreak has spread to the capital and port towns, infecting more than 100 people in just a few weeks. Plague can be cured using common antibiotics if delivered early. Antibiotics can also help prevent infection among people who have been exposed to plague.

Knowledge resources for plague responders

This introductory-level online course aims to equip decision-makers and frontline responders with a set of resources containing critical information on human plague. These resources, including a video lecture and a presentation, can be used as a refresher for experienced personnel or as an introduction of the topic for everyone else. Most of the materials are available in English and French, and can be downloaded for offline use.

What is plague?

WHO/E. Bertherat

One of the oldest identifiable diseases known to man, plague remains endemic in many natural foci around the world. It is still widely distributed in the tropics and subtropics and in warmer areas of temperate countries. Essentially a disease of wild rodents, plague is spread from one rodent to another by flea ectoparasites and to humans either by the bite of infected fleas or when handling infected hosts. Recent outbreaks have shown that plague may reoccur in areas that have long remained silent.

Untreated, mortality - particularly from pneumonic plague - may reach high levels. When rapidly diagnosed and promptly treated, plague may be successfully managed with antibiotics such as streptomycin and tetracycline, reducing mortality from 30%-100% to less than 15%.

Plague is an infectious disease caused by the bacteria Yersinia pestis, a zoonotic bacteria, usually found in small mammals and their fleas. It is transmitted between animals from their fleas. Humans can be contaminated by the bite of infected fleas, through direct contact with infected materials or by inhalation. Plague can be a very severe disease in people, particularly in its septicaemic and pneumonic forms, with a case-fatality ratio of 30%-100% if left untreated.

People infected with plague usually develop “flu-like” symptoms after an incubation period of 3-7 days. Typical symptoms are the sudden onset of fever, chills, head and body-aches and weakness, vomiting and nausea.

There are 3 forms of plague infection, depending on the route of infection: bubonic, septicaemic and pneumonic.

Bubonic plague is the most common form of plague and is caused by the bite of an infected flea. Plague bacillus, Y. pestis, enters at the bite and travels through the lymphatic system to the nearest lymph node where it replicates itself. The lymph node then becomes inflamed, tense and painful, and is called a "bubo". At advanced stages of the infection the inflamed lymph nodes can turn into suppurating open sores. There is no inter human transmission of bubonic plague.

Septicaemic plague occurs when infection spreads through the bloodstream Septicaemic plague may result from flea bites and from direct contact with infective materials through cracks in the skin. Advanced stages of the bubonic form of plague will also lead to direct spread of Y. pestis in the blood.

Pneumonic plague-or lung-based plague- is the most virulent and least common form of plague. Typically, the pneumonic form is caused by spread to the lungs from advanced bubonic plague. However, a person with secondary pneumonic plague may form aerosolized infective droplets and transmit plague via droplets to other humans. Untreated pneumonic plague has a case-fatality ratio close to 100%.

Confirmation of plague requires lab testing. The best practice is to identify Y. pestis in a sample of puss from a bubo, blood or sputum. A specific Y. pestis antigen can be detected by different techniques. One of them is a Rapid dipstick test, which was validated in the field and is now widely used in in Africa and South America, with the support of WHO.

Untreated plague can be rapidly fatal, so early diagnosis and treatment is essential for survival and reduction of complications. Antibiotics and supportive therapy are effective against plague if patients are diagnosed in time.

Preventive measures include informing people when zoonotic plague is present in their environment and advising them to take precautions against flea bites and not to handle animal carcasses. People, especially health workers, should also avoid direct contact with infected tissues such as buboes, or close exposure to patients with pneumonic plague.

Based on the available information to date, the risk of international spread of plague appears very low. WHO advises against any restriction on travel or trade on Madagascar based on the available information. International travellers should be informed about the current plague outbreak, the fact that plague is endemic in Madagascar, and should receive advice on prevention, post exposure chemoprophylaxis, and where to seek medical treatment should they develop plague related symptoms. Read the full travel advice here.