A recent lab experiment indicates that human body lice may be better at spreading Yersinia pestis, the bacterium responsible for the plague, than previously believed. This supports the idea that they may have played a role in past pandemics. David Bland and his team at the National Institute of Allergy and Infectious Diseases in the United States shared these findings.The findings were published in the open-access journal PLOS Biology on May 21.
Y. pestis has caused many pandemics, such as the Black Death in the Middle Ages that killed millions of people in Europe. It naturally moves between rodents and fleas, and sometimes fleas infect humans through bites. Therefore, fleas and rats are believed to be the main causes of plague pandemics. Body lice, which feed on human blood, can also carry Y. pestis, but are generally considered to be too inefficient at spreading it to substantially contribute to outbreaks. However The efficiency of lice transmission varies widely. Bland and colleagues conducted laboratory experiments to better understand the potential role of body lice in the transmission of the plague. They used membrane feeders to simulate human skin and studied the transmission potential in a controlled environment. Their experiments showed that body lice could become infected with the plague bacteria, Y. pestis, and were able to transmit it after feeding on blood containing similar levels of the pathogen found in actual cases.
Research has shown that Y. pestis, the bacteria responsible for the plague, can infect the Pawlowsky glands in body lice, leading to more consistent transmission of the pathogen. The Pawlowsky glands are salivary glands found in body lice, and it is believed that they secrete lubricant onto the lice’s mouthparts. Infected lice may contaminate mouthparts with Y. pestis, which can then spread to humans when they are bitten. This suggests that body lice may be more effective at spreading Y. pestis than previously thought.
The researchers discovered that human body lice are better at spreading the Yersinia pestis bacteria than previously believed, and they might have played a part in past plague outbreaks. They also found that lice can transmit the bacteria in more than one way. The study revealed a new bite-based mechanism in which a specific set of salivary glands unique to lice, called the Pawlowsky glands, become infected with Y. pestis and secrete lubricant containing plague bacilli onto the insect’s mouthparts before feeding on blood.
