Answer :

organ specific and tissue manifestation. human body has a number of organs, tissues and systems. every pathogen has developed adaptation to infect a particular organ, tissue or system. in some cases the organ or tissue specificity depends upon the portal of entry while in others it is not so. a few examples are mentioned as follows:
1. if disease-causing microbes enter with air via the nose, they are likely to go to the lungs, e.g., bacteria which causes T.B of lungs.
2. virus that causes HIV infection, enters the body through sexual organs during sexual contact and then tends to spread to lymph nodes throughout the body.
3. malaria-causing microbes are transmitted through mosquito bite, and move to the liver and then to the red blood cells

Different species of microbes seem to have evolved to home in on different parts of the body. In part, this selection is connected to their point of entry. If they enter from the air via the nose, they are likely to go to the lungs. This is seen in the bacteria causing tuberculosis. If they enter through the mouth, they can stay in the gut lining like typhoid causing bacteria Or they can go to the liver,like the viruses that cause jaundice. But this needn.t always be the case. An infection like HIV,  that comes into the body thru the sexual organs, will spread to lymph nodes all over the body. Malaria-causing microbes, entering through a mosquito bite, will go to the liver, and then to the red blood cells. The virus causing Japanese encephalitis, or brain fever, will similarly enter through a mosquito bite. But it goes on to infect the brain. 

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