PlaguePlague outbreak: where does it still exist, and could it spread?
An outbreak of plague has been occurring in Madagascar, with more than 2,000 cases and 170 deaths reported since August 2017. This island nation is one of the few remaining hotspots for plague in the world, with cases usually reported between September and April each year. It’s not possible to eradicate plague, as it is widespread in wildlife rodents outside the sphere of human influence. Outbreaks generally are managed reactively by “firefighting teams” deployed to clear houses of fleas, identify and treat cases and give pre-emptive treatment to contacts at risk. A more preventative approach, such as the identification of areas at risk using climate models and animal surveys to focus flea and rat control efforts would be better. But this requires a better understanding of transmission pathways in each region where disease persists.
Professor Allen Cheng, Monash University // Source: monash.edu
An outbreak of plague has been occurring in Madagascar, with more than 2,000 cases and 170 deaths reported since August 2017.
This island nation is one of the few remaining hotspots for plague in the world, with cases usually reported between September and April each year.
But this outbreak has been unusual, as it has affected many different areas in Madagascar, including heavily populated cities.
What is plague, and how is it treated?
Plague is a serious disease caused by the bacteria Yersina pestis. It has a high death rate if untreated. There are several different clinical forms, including bubonic plague (affecting the lymph nodes), pneumonic plague (affecting the lungs) and septicaemic plague (involving the bloodstream).
Outside of outbreak situations, deaths from plague are usually due to delays in recognition and diagnosis, rather than a lack of treatment options. Although antibiotic resistant strains have been described, plague can generally be treated with a number of commonly available antibiotics.
Why does plague still exist?
Plague was responsible for hundreds of millions of deaths in three devastating pandemics, including the Plague of Justinian in the 6th century, the Black Death in the 14th century, and the Third Pandemic that originated in China in the 19th century.
In these pandemics, it’s generally thought plague was introduced by rats (often transported on ships) then transmitted to local rats in domestic settings. Fleas then transmit the bacterium between infected rats and humans. But there’s still some debate on the transmission pathways of plague in these pandemics. The classical cycle between an animal reservoir (rats) to humans through an insect vector (fleas) is common to many animal-associated infectious diseases, known as zoonoses.
The pattern of plague cases seems to have changed to a more complex ecology over the past 50 years. There has been a shift in cases from Asia to Africa and the re-emergence of disease in other areas such as the United States.
