Pathogenicity in the context of Protozoan

Leprosy, also known as Hansen's disease (HD), is a long-term infection by the bacteria Mycobacterium leprae or Mycobacterium lepromatosis. Infection can lead to damage of the nerves, respiratory tract, skin, and eyes. This nerve damage may result in the loss of nociception, which can lead to the loss of parts of a person's extremities from repeated injuries or infection through unnoticed wounds. An infected person may also experience muscle weakness and loss of eyesight. Leprosy symptoms may begin within one year or take 20 years or more.

Leprosy is spread between people, although extensive contact is necessary. Leprosy has a low pathogenicity, and 95% of people who contract or who are exposed to M. leprae do not develop the disease. Spread is likely through a cough or contact with fluid from the nose of a person infected by leprosy. Genetic factors and baseline immune function play a role in how easily a person catches the disease. Leprosy is not spread during pregnancy to the unborn child or through sexual contact. Leprosy occurs more commonly among people living in poverty. There are two main types of the disease—paucibacillary and multibacillary, which differ in the number of bacteria present. A person with paucibacillary disease has five or fewer poorly pigmented, numb skin patches, while a person with multibacillary disease has more than five skin patches. The diagnosis is confirmed by finding acid-fast bacilli in a biopsy of the skin.

Xanthomonas campestris is a gram-negative, obligate aerobic bacterium that is a member of the Xanthomonadaceae, a family of bacteria that are commonly known for their association with plant disease. This species includes Xanthomonas campestris pv. campestris, the cause of black rot in brassicas (cruciferous vegetables), one of the most important diseases of brassicas worldwide.

These bacteria are facultative saprophytes, meaning that they are typically parasitic while also having the ability to live on dead or decaying organic matter under the proper conditions. Upon initial infection, the bacteria remain in the epiphytic stage; however, the harmful endophytic stage is reached when the bacteria actually enter the plant host through natural openings. In general, the genes that contribute significantly to the plant-bacteria relationship are the avirulence (avr) genes, the hypersensitivity response and pathogenicity (hrp) genes, and the pathogenicity factors (rpf) genes. Additionally, the virulence determinants associated with the seedborne diseases that result from this bacterium include extracellular enzymes, polysaccharides, lipopolysaccharides, etc.