On 29 August 2021, the Public Health, Epidemiological Surveillance and Response Department of the Ministry of Health, Madagascar received an alert from Arivonimamo health district, Itasy region, regarding a suspected community death and 15 suspected cases of pneumonic plague that occurred in the municipality of Miandrandra. All the cases presented with fever, headache, weakness, shortness of breath, chest pain and cough. Plague is endemic in Madagascar and outbreaks occur regularly, although every outbreak is cause for concern. Furthermore, pneumonic plague is a notifiable disease under the International Health Regulations 2005.
By the following day, 30 August, 25 suspected cases of pneumonic plague had been notified to the health authorities from Arivonimamo district, Itasy region, including six deaths (three community deaths and three at Miandrandra health facility), 19 of which were admitted at Miandrandra health facility for treatment. A total of 20 samples (8 sputum and 12 blood) were collected the same day for laboratory confirmation at the Pasteur Institute of Madagascar.
As of 15 September 2021, a total of 20 suspected and 22 confirmed cases of plague have been notified. The median age of cases is 36 years (range 3 to 74 years), 22 cases are males and 20 are females. Reported cases are geographically located in two non-bordering regions: Itasy (3 affected municipalities in Arivonimamo district) and Haute Matsiatra (1 affected municipality in Ambalavao district). Both regions are known plague endemic areas, and during the 2017 outbreak they were highly affected with Ambalavao being the main epicenter.
Among confirmed cases, 19 have clinically presented as pneumonic plague and three as bubonic plague. Eight deaths occurred among confirmed cases (2 among bubonic plague cases and 6 among pneumonic plague cases) leading to a case fatality ratio of 37% (8/22). Of them, 4 were males and 4 females, 3 occurred in the community level and 5 at health facilities.
Overall, 1,064 close contacts of cases have been identified, followed up, and received chemoprophylaxis with cotrimoxazole or doxycycline. Active case finding in the communities was undertaken in all the health districts reporting cases. Health authorities, in collaboration with the Pasteur Institute of Madagascar, carried out animal surveillance in Arivonimamo district during the initial investigation on 30 August. Preliminary results showed a carriage of Yersinia pestis, the causative bacterium, in 1.3% of the rats, exceeding the alert threshold of 1%, while the pulicidal index (the ratio between the total number of fleas collected from rats captured over the total number of rats captured) was 1.7, which did not exceed the alert threshold of more than 5. Analyses were also performed in Faratsiho (Vakinakaratra region) and Besarety (Analamanga region), which are part of the endemic regions, resulting in a pulicidal indexes at 3.1 and 3.2, respectively.
Public health response
Interventions against pneumonic plague outbreaks are carried out by the local teams at the community level under the supervision of the district and regional teams. These teams are supported by the central level of the Ministry of Health, the Pasteur Institute of Madagascar and a number of partners including WHO. The following are actions taken and activities carried out for the management and control of this outbreak:
Diagnosis and case management:
- Collection of samples from suspected cases; use of rapid diagnostic tests; shipment of samples for further analysis and confirmation to the Pasteur Institute of Madagascar
- Management of reported cases in healthcare facilities
- Training of health workers on the management of plague cases
- Activation of plague control committees in areas that have notified cases
Epidemiology and surveillance:
- Active case finding, active search for close contacts with subsequent chemoprophylactic management using cotrimoxazole as first-line and doxycycline in case of contraindication to sulphonamides
- Strengthening of community surveillance and surveillance at the level of health facilities
- Animal surveillance
- Disinfection of the homes of affected people: spraying the households of cases with HTH (calcium hypochlorite) solution as a disinfectant
- Vector control and anti-reservoirs measures
- Sensitization of the population on plague prevention measures in the affected areas, what symptoms to monitor for, and when to seek care in health facilities
WHO risk assessment
Plague is endemic in Madagascar and cases are reported each year in bubonic and pneumonic forms. The favorable season for transmission of the disease generally lasts from September to April. Cases are usually reported from the central highlands of the country, located at an altitude of over 700 meters, as is the situation with the current outbreak involving the regions of Itasy and Haute Matsiatra. Between 200 and 400 cases of plague are usually notified each year by the Ministry of Public Health, mainly in the bubonic form.
The country experienced an epidemic of pneumonic plague in 2017, which was unusual because of its magnitude and its urban character affecting major cities of the country.
This form of plague is very severe and almost always fatal if it is not treated promptly. It develops either by inhaling respiratory droplets from an infected person or as a result of untreated bubonic plague after the bacteria have spread to the lungs.
Madagascar has a long history of responding to plague outbreaks. It has already adopted several prevention and response plans, such as the National Strategy for the Prevention and Control of Plague. Unfortunately, the weak financial capacity of the country prevents the establishment of an adequate preparedness and response strategy. The existence of other epidemics like COVID-19 and the ongoing humanitarian nutrition and food crisis in the south of the country are straining the health system and reducing the country's capacity to cope with other crises. The affected areas are geographically close to the capital of the country and the movement of the population increases the risk of spreading the disease to urban areas and other areas of the country.
Thus, the risk at the national level is considered high, while at the regional and global levels this risk is low since there is no known history of exporting plague cases to other countries. Additionally, as Madagascar is an island country, the implementation of response measures is particularly effective at preventing the export of cases.
WHO recommends the following actions for the management of plague outbreaks:
Find and eliminate the source of infection: Identify the most likely source in the area where the human cases have been reported, typically looking for clustered areas where small animals have died in large numbers. Put in place appropriate procedures to prevent and fight infection. Control vectors and rodents. Rodent control should only be undertaken after effective disinfection measures have been implemented.
Protect health workers: inform them and train them in infection prevention and control. Those in direct contact with patients with pneumonic plague should apply enhanced protective measures (personal protective equipment) and take antibiotic chemoprophylaxis for at least seven days or as long as exposure to infected patients lasts.
Ensure rapid and appropriate treatment: check that adequate antibiotic therapy is administered to patients and that there are sufficient stocks of antibiotics locally.
Isolate patients with pneumonic plague: patients with pneumonic plague should wear a mask as long as their clinical condition allows.
Monitor and protect: identify and monitor close contacts of pneumonic plague patients and administer chemoprophylaxis for 7 days. Depending on the circumstances of the contamination, members of a household where patients with bubonic plague live should also receive chemoprophylaxis as they are also likely to have been bitten by infected fleas.
Collect the necessary samples according to the clinical form (blood, pus, sputum) using appropriate procedures to prevent and control infection, and send them as soon as possible to the laboratory for analysis. This procedure should not delay the start of antibiotic therapy.
Perform dignified and safe burials: a person who has died of plague, regardless of the form of the disease, presents a risk of contagion. The body should only be handled by personnel trained in this task.