The circular ones are used as landing pads by T helper cells the immune system

The circular ones are used as landing pads by t

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The circular ones are used as landing pads by T helper cells, the immune system managers. Activation commences following docking. The T killer cell has its own landing pad on the square shape. The killer cell is activated by a command from the helper cell. It divides itself and the hunt for virus-infected cells can begin. The infected cells also highlight parts of the pathogens. They are thus identified as targets for killer cells, and messenger chemicals trigger the cell's demise. The destruction of infected cells nips virus reproduction in the bud. Pathogenic agents are often very difficult to identify. Immunofluorescence has proven to be a helpful method. Specially prepared fluorescent antibodies attach to certain viruses or parasites. Their light trails unmask the pathogens. Slow-growth parasites are often not noticed until several weeks after a trip to the tropics. This type is diagnosed as Leishmania, caused by a monocellular organism transmitted through the bite of a sand fly. A visible sign is a deep wound on the back, caused by the body's futile defensive reaction. Leishmania has an especially devious survival strategy. The oblong parasite lets itself be captured and carried by a phagocyte as a stowaway into the body's interior. There it hides in a cavity, where it is able to reproduce undisturbed. Leishmaniosis is one of the seven common tropical diseases. Twelve million people
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are affected worldwide, among them an increasing number of tourists. Leishmania can attack not only the skin, but also inner organs. Treatment usually lasts several weeks. Patient: I was in a Peruvian jungle in May and June, in a tropical forest, for about five weeks. There, we were bitten by all sorts of creatures. I think that's where this happened, from a mosquito." Simon Karalus's trip through the Manu National Park in Peru unexpectedly turned into a survival training adventure. Poorly prepared and with insufficient food and medicines, he lost his way and wandered aimlessly in the rainforest for weeks. Half starved, he finally found his way back. He had no idea that he might be one of the 400,000 people infected by Leishmania each year. Prof. Kurth: On holiday trips, especially into the tropics, people are naturally at risk because they come in contact with a totally or largely different world of pathogenic agents. This may result in a harmless infection of the respiratory or gastrointestinal tract that then leads to Montezuma's Revenge, which ends up as diarrhea. Or there may be graver consequences if the pathogens are nastier, such as those transmitted through mosquitoes, of which there are plenty. With this degree of risk, the natives are not any yardstick for making comparisons, because they get infected in their own environment as youths. Whoever survives such an infection, becomes immune and will rarely get sick in adulthood. On the other hand, we are at a relatively high level of risk when traveling to these regions without such natural immunity."
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  • Fall '16
  • Jeff Miller

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