Urban Legend Dogma of Bubonic Plague Infection Exploit Corrected

""For decades, scientists have thought the bacteria that cause the bubonic plague hijack host cells at the site of a fleabite and are then taken to the lymph nodes, where the bacteria multiply and trigger severe disease. But UNC School of Medicine researchers discovered that this accepted theory is off base. The bacteria do not use host cells; they traffic to lymph nodes on their own and not in great numbers.

In fact, most of the plague-causing bacteria – called Yersinia pestis – get trapped in a bottleneck either in the skin, while en route to the lymph node, or in the node itself. Only a few microbes break free to infect the lymph node and cause disease.

“Anytime you find something where the host is winning, you want to exploit it,” said Virginia Miller, PhD, professor of microbiology and immunology and senior author of the paper in PLoS Pathogens. “If we can understand how the host and the bacteria contribute to this bottleneck, then this could become something we’d target so we could either ramp up what’s causing the bottleneck or slow down the infection.”

The discovery offers much needed information about how virulent insect-borne diseases, such as plague, malaria, and dengue virus cause infection. The findings also present new routes for research on how bacterial strains cause disease despite the immune system’s best efforts.

The plague, which killed millions of people during the Middle Ages, is contracted by several people each year in the western United States. Outbreaks have occurred in the recent past in India and Africa, and one is unfolding right now in Madagascar. Standard antibiotics are effective against Y. pestis if taken early enough. But infection can go undetected for days, making diagnosis difficult and antibiotics less effective the longer the bacteria take root.

There are three kinds of plague all caused by Y. pestis: bubonic, which is contracted through fleabite; pneumonic, which is contracted by breathing in the bacteria; and septicemic, which is a severe infection of blood.

Miller’s team studies the pneumonic and bubonic versions. Three years ago, Rodrigo Gonzalez, PhD – a UNC graduate student at the time and now a postdoctoral fellow at Harvard – searched the scientific literature for data confirming the accepted notion that Y. pestis gets trafficked by human phagocytic cells from the fleabite site to the lymph nodes.

Scientists readily accepted this idea because when Y. pestis microbes are added to phagocytic cells in culture, the cells do soak up the bacteria.
Phagocytes essentially eat harmful microbes, and because these cells traffic through the lymphatic system, scientists came to the logical conclusion that phagocytes take the Y. pestis to the lymph nodes.""

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http://www.biosciencetechnology.com/news/2015/02/scientists-overturn-dogma-bubonic-plague