Pneumonic plague, measles, and “Covid-19”...which are more likely to spread?

- The World Health Organization announced on Wednesday that it still lacks clear information regarding the recent death of a worker at a Russian institute specializing in plague research. This death raised increasing global concerns about a rare form of the disease, especially after hundreds of direct contacts were subjected to isolation, amid reports that another worker might be infected with pneumonia.

Pneumonic plague is a rare and fatal lung infection caused by the bacterium Yersinia pestis. Pneumonic plague is the only form of bacterial infection that is transmitted directly from person to person, and the last documented case of pneumonic plague being transmitted between humans in the United States dates back to 1924, during an outbreak of the disease in the American city of Los Angeles.

How does the spread of pneumonic plague compare to other infectious diseases? Studies suggest that the basic reproduction rate (R₀) of pneumonic plague is between 1.1 and 1.3, meaning that an infected person may infect between 1.1 and 1.3 people on average, through respiratory droplets from coughing or sneezing.

The infection can also be transmitted through droplets from infected animals. The basic reproduction rate measures the average number of people a single infected person can infect, before outbreak control measures are put in place.

Compared to other infectious diseases, pneumonic plague is less likely to spread, as its basic reproduction rate is about 1.3, compared to 1.95 for Ebola, 2.12 for Hanta virus, and 5.94 for the delta variant of Covid-19, while measles tops the list with a rate ranging between 12 and 18 secondary infections per case. Plague can be treated with antibiotics, usually for 10 to 14 days. The most commonly used medications include ciprofloxacin, levofloxacin, moxifloxacin, gentamicin, and streptomycin.

Patients' chances of survival increase significantly when treatment with antibiotics begins within the first 24 hours of the onset of symptoms. Treatment may also include supportive care, such as providing the patient with oxygen and fluids, along with adequate rest.

At the same time, the World Health Organization emphasized that the level of risk to the general population appears low.