![]() When rodents die from the plague, fleas jump to a new host, biting them and transmitting Y. Scientists have more recently discovered that a flea that lives on rats, Xenopsylla cheopis, primarily causes human cases of plague. Rats have long been thought to be the main vector of plague outbreaks, because of their intimate connection with humans in urban areas. When the bacteria pass to other species, during an epizootic cycle, humans face a greater risk for becoming infected with plague bacteria. pestis can circulate at low rates within populations of rodents, mostly undetected because it doesn’t produce an outbreak. Many small mammals act as hosts to the bacteria, including rats, mice, chipmunks, prairie dogs, rabbits, and squirrels. Once these cells are knocked out, the bacteria can multiply unhindered. pestis disables the immune system of its host by injecting toxins into defense cells, such as macrophages, that are tasked with detecting bacterial infections. ![]() pestis is an extraordinarily virulent, rod-shaped bacterium. In 1894, Alexandre Yersin discovered the bacterium responsible for causing plague: Yersinia pestis. But keen observations and advances in microscopes eventually helped unveil the true culprit. ![]() What is plague? How many people died from the Black Death and the other plague pandemics? Learn about the bacterium behind the plague disease, how factors like trade and urbanization caused it to spread to every continent except Antarctica, and how three devastating pandemics helped shape modern medicine.įor hundreds of years, what caused plague outbreaks remained mysterious, and shrouded in superstitions.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |