The latest plague outbreak in Sub-Saharan Africa

There is currently an outbreak of both pneumonic and bubonic plague in Madagascar. This crisis situation was the focus of a November 6 report affirming the countrywide spread of the plague epidemic, with disease cases growing by 37% over five days, from 1,309 to 1,801, according to the World Health Organization (WHO).  As Madagascar enters the expected peak epidemic season (November to April), plague cases have already caused at least 127 deaths.


Early disease onset

Investigators are surprised at this early plague onset this year, which is in sharp contrast to other years when the period November to April usually reported about 400 annual bubonic plague cases. Two-thirds of the recorded cases in Madagascar have been caused by the pneumonic plague, transmitted through coughs and sneezes, and proving fatal within 24 hours, if no treatment is given.

It is important to figure out who was patient zero – the patient who, in early August, progressed from untreated bubonic disease to the pneumonic form, and then transmitted it to someone en route to Toamasina. Since the pneumonic disease occurred at a time when it was not expected to occur, it went undiagnosed for a prolonged time duration, resulting in intense transmission in that locality. While most cases recorded in Madagascar occurred in remote areas, this outbreak has also affected large urban cities such as the capital Antananarivo and the port city of Tamatave.

Understanding how the disease spread and what danger it poses are critical in preventing further spread to other countries. While control measures have been put in action, the WHO has placed nine nearby countries on alert to curb further spread, including international travel zones such as Mauritius and the Seychelles (See Figure 1).


Figure 1: The nine countries neighboring Madagascar that have been placed on alert by the WHO.


It is critical to cut the transmission chain and focus resources to specific disease-ridden areas of the country. Present control measures include the following sanitation procedures: use of face masks to prevent disease spread through coughing and disinfecting affected areas, such as the marketplace of Anosibe (Anosibe district) in Antananarivo. Additionally, patients are being treated at health centers such as the Plague Triage and Treatment Center in Toamasina.

The three forms of plague are as follows:

  • Bites from fleas (often borne by rodents) carryingYersinia pestis spread bubonic plague, causing fever, weakness and painfully swollen lymph nodes.
  • Septicemic plague is characterized by blood infection resulting in the rotting of skin and tissue.
  • When untreated, infections spread to the lungs, causing pneumonic plague which spreads directly from person to person, and is 100% fatal without antibiotics.

The disease can be stopped with rapid diagnosis and quick medical treatment.  With the large numbers currently affected, however, extra resources are needed in the form of trained local health workers to diagnose the disease, treat those infected and trace the potential contacts of infected individuals. Immediate action is necessary to contain this unusual and disturbing outbreak.

This snapshot from the Incidence and Prevalence Database from Clarivate Analytics provides incidence data and highlights the high numbers of new plague infections reported in Madagascar in 2015-2016, as a backdrop to this year’s alarming outbreak:


Incidence (new cases) 

Region/Country Incidence Rate (per 1,000,000) Incidence Number Population*
North America
U.S. 0.05 16 326,625,791
Latin America
Peru 0.8 24 31,036,656
Mongolia 1.0 3 3,068,243
Democratic Republic Of Congo 0.2 18 83,301,151
Madagascar 11.0 275 25,054,161
Tanzania 0.1 5 53,950,935
Uganda 0.1 3 39,570,125
Africa see notes 301 see notes
Americas see notes 16 see notes
Asia see notes 3 see notes
Worldwide 0.04 320 7,400,786,496


* Calculations are based on the current year’s census figure from the U.S. Census Bureau, regardless of the year reported in the original source. Census figures represent the total population or a population subset, depending on the age group specified. See the Notes section for more details.

Original Source: Bertherat E; “Plague Around the World, 2010-2015.” Weekly Epidemiological Record; V.91; No.8; 2/26/16; p89 

Notes: Numbers/rates reported by the original source appear in bold type.

For the countries (U.S., Mongolia, Democratic Republic of Congo, Madagascar, United Republic of Tanzania, and Uganda), number of plague cases are reported for 2015; census figures for all ages applied to incidence number to calculate rate. For Peru, number of plague cases are reported for 2013; census figures for all ages applied to incidence number to calculate rate.

For the regions (Africa, Americas, Asia), number of plague cases are reported for 2015; no census figure available; no calculations made.  For Worldwide data, number of plague cases reported in 2015; census figure for all ages applied to incidence number to calculate rate.

Download the full report, “The plague takes over – Latest plague outbreak in Sub-Saharan Africa” for free here.

For epidemiological data on diseases mentioned in the paper, learn more about the Incidence and Prevalence Database.