A recently published study has found that the 2013 plague outbreak in Madagascar was a result of a new drug-resistant strain.
Although the ‘Black Death’ took place centuries ago, the plague still remains prevalent in various parts of the world. According to the World Health Organization (WHO), more than 3,000 cases and 584 deaths occurred worldwide between 2010 and 2015. Madagascar, the Democratic Republic of Congo, and Peru are considered the most endemic countries. Additionally, Madagascar accounts for most global human plague cases and has given rise to three drug-resistant strains of the disease.
The causative agent, Yersinia pestis enters the bloodstream thanks to a flea bite. Once inside the blood, it can then infect the lungs, resulting in the pneumonic plague – the most virulent of all. If left untreated, the disease can be 100% lethal. Moreover, pneumonic plague is the most contagious type as it easily spreads human-to-human via respiratory droplets.
Now, researchers at Northern Arizona University’s Pathogen and Microbiome Institute have isolated a drug-resistant strain from Madagascar’s 2013 pneumonic plague outbreak. Moreover, they also found evidence of the drug-resistant strain spreading from person-to-person.
We determined – for the first time – that AMR strains of Y. pestis can be transmitted person-to-person.
Professor Dave Wagner, lead researcher
Streptomycin Resistance
In February 2013, the Faratsiho district in Madagascar experienced a pneumonic plague outbreak. It resulted in 22 cases and three fatalities. The team at North Arizona University analyzed the samples from this outbreak and conducted genome sequencing of the Yersinia pestis isolates. They published their findings in the journal Clinical Infectious Diseases.
According to the study, the strain of Yersinia pestis was resistant to streptomycin. This widely used antibiotic is most effective against plague and is the first drug of choice. Especially, in pneumonic plague.
The [antimicrobial resistant] AMR strain from this outbreak is resistant to streptomycin due to a spontaneous point mutation, but is still susceptible to many other antibiotics, including co-trimoxazole. Luckily, the 19 cases that were treated all received co-trimoxazole in addition to streptomycin, and all of them survived.
Professor Dave Wagner, lead researcher
Professor Dave Wagner, who led the study, further added that such drug-resistant strains are rare. Moreover, no other outbreaks with the mutated strain have occurred since then.
Antibiotics and symptomatic treatment are quite effective against plague. However, they are only effective if administered in time. Especially, in pneumonic plague where the case can become fatal within 18-24 hours of disease onset. Since most cases are located in remote areas, early diagnosis and treatment are not only possible. Moreover, antibiotic resistance further complicates matters. Therefore, researchers are looking into plague vaccines for preventing and controlling outbreaks. One such vaccine is already undergoing a clinical trial at the University of Oxford.
Reference:
Voahangy Andrianaivoarimanana, David M Wagner, Dawn N Birdsell, Birgit Nikolay, Faniry Rakotoarimanana, Lovasoa N Randriantseheno, Amy J Vogler, Jason W Sahl, Carina M Hall, Nawarat Somprasong, Simon Cauchemez, Herbert P Schweizer, Harimahefa Razafimandimby, Christophe Rogier, Minoarisoa Rajerison, Transmission of Antimicrobial Resistant Yersinia pestis During a Pneumonic Plague Outbreak, Clinical Infectious Diseases, 2021;, ciab606, https://doi.org/10.1093/cid/ciab606
