New data released by the World Health Organization (WHO) reveals that for the six years from Jan. 1, 2010 to Dec. 31 2015,  3248 cases of plague in humans were reported, resulting in 584 deaths.

Oriental rat flea, Xenopsylla cheopis/CDC

Of this total, Madagascar is the most seriously affected country in the world with 74 percent of all cases globally with 2,404 and eight out 10 human plague deaths (476). More serious forms of plagues such as pneumonic plague has resulted in an increase in the overall case fatality rate.

The Democratic Republic of the Congo (586 cases), Uganda (72) and Tanzania (61) round out the top four countries.

In the Americas, Peru regularly reports cases in 4 regions in the north-west of the country, where new foci emerged in 2013. These are essentially sporadic cases of bubonic plague associated with farming activities in rural areas. During the six year period, Peru saw 64 cases and 7 deaths.

The United States saw the second most human plague cases in the Americas with 39, including 5 deaths. Sixteen cases and 4 deaths were reported in 2015 alone.

Asia saw 17 human plague cases and eight fatalities during the past six years with more than half reported from China (10).

Related: Congo, Madagascar top countries reporting most plague 2000-2009, US reports 57 cases

Plague is a bacterial infection mainly affecting small mammals and transmitted by fleas. The geographical distribution of the disease is very focalized. Occasionally, the pathogen Yersinia pestis can infect humans through infected flea bites. Human plague is a serious disease, particularly in its septicaemic and pneumonic forms. The pneumonic form, invariably fatal unless treated early, is especially contagious and can trigger terrifying epidemics through direct person-to-person contact. In these circumstances, plague is simultaneously a medical and a public health emergency.