Plague – Madagascar
On 23 August 2017, a 31-year-old male from Tamatave, visiting Ankazobe District in central highlands, developed malaria-like symptoms. On 27 August, he developed respiratory symptoms during his journey in a shared public taxi from Ankazobe District to Tamatave (via Antananarivo). His condition worsened and he died. His body was prepared for a funeral at the nearest hospital, Moramanga District Hospital, without safety procedures. Additionally, 31 people who came into contact with this case either through direct contact with the primary case or had other epidemiological links, became ill, and four cases of them died.
The outbreak was detected on 11 September, following the death of a 47-year-old woman from Antananarivo, who was admitted to a hospital with respiratory failure caused by pneumonic plague. The public health authorities Direction de la Veille Sanitaire et de la Surveillance Epidémiologique (DVSSE) immediately launched field investigations.
As of 28 September 2017, a total of 51 cases (suspected, probable and confirmed) of pneumonic plague, including 12 deaths were reported in the country. The diagnosis was confirmed by the Institut Pasteur de Madagascar by polymerase chain reaction test and using rapid diagnostic test.
In addition to the 51 suspected, probable and confirmed cases of pneumonic plague, and during the same period another 53 cases of bubonic plague including seven deaths have been reported throughout the country. One case of septicaemic plague has also been identified and they were not directly linked to the outbreak.
Public health response
The Ministry of Health activated crisis units in Antananarivo and Toamasina and all cases have been provided access to treatment at no cost. Active case finding and contact tracing are on-going and all pneumonic cases are being isolated and treated, and all contacts are receiving chemoprophylaxis.
There are additional ongoing key public health response measures which include:
- Ongoing investigation of new cases.
- Strengthening of the epidemiological surveillance in the affected and surrounding districts, including contact identification, administration of chemoprophylaxis, and monitoring close contacts of pneumonic plague cases.
- Disinsection of affected areas, including rodent and vector control.
- Raising awareness of the population about prevention and actions after exposure.
- Raising awareness among health care workers and providing information including infection control measures, and implementation of safe burial practices.
WHO risk assessment
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.
There are three forms of plague infection, depending on the route of infection: bubonic, septicaemic and pneumonic.
- Bubonic plague (known in mediaeval Europe as the 'Black Death') is the most common form of plague and is caused by the bite of an infected flea. Plague bacillus, Yersinia 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 open sores filled with puss.
- Pneumonic plague-or lung-based plague- is the most virulent form of plague. Incubation period can be as short as 24 hours. 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 is always fatal.
- Septicaemic plague occurs when infection spreads through the bloodstream, following a bubonic or a pneumonic plague.
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. The pneumonic form is invariably fatal unless treated early, is especially contagious and can trigger severe epidemics through person-to-person contact via droplets in the air.
Plague is an endemic disease in Madagascar; cases of bubonic plague are reported nearly every year, during the epidemic season (between September and April). However, the ongoing pneumonic plague event has been reported in a non-endemic area and in densely populated coastal cities for the first time.
Pneumonic plague is a form of plague that is transmissible from person-to-person, with a potential to trigger severe epidemics if inadequately controlled. Detection of this outbreak occurred more than two weeks after the first case died during which cases travelled to different parts of the country, including the capital Antananarivo. Therefore, the overall risk at the national level is high. The overall regional risk is moderate due to frequent flights to neighboring Indian Ocean islands. The global risk is low.
Prevention and control measures
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. The most rapid and effective method for controlling fleas is to apply an appropriate insecticide formulated as a dust or low-volume spray. People, especially health workers, should also avoid direct contact with infected tissues such as buboes, or close exposure to patients with pneumonic plague. Important prevention and control measures include:
- Find and stop the source of infection.
- Protect health workers: inform and train them on infection prevention and control.
- Isolate: patients with pneumonic plague. They should be isolated so as not to infect others via air droplets.
- Surveillance: identify and monitor close contacts of pneumonic plague patients and give them a seven day chemoprophylaxis.
- Obtain specimens which should be carefully collected and sent to labs for testing.
- Ensure safe burial practices.
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.
WHO advises against any restriction on travel or trade on Madagascar based on the available information. It is recommended to provide information at the ports of entry (airports, seaports) of Madagascar about the disease and the necessary protection measures required.
For more information, please see the WHO plague fact sheet link below: