I. AIDS:
Aids is a retrovirus infected by human immunodeficiency virus. Because of the destruction of the immune system, AIDS has gradually become the target of many opportunistic diseases, resulting in a variety of clinical symptoms.
Second, tuberculosis:
Tuberculosis is a chronic infectious disease caused by Mycobacterium tuberculosis, which can invade many organs, especially tuberculosis infection. Bacterial secretions are an important source of infection. The human body may not get sick after being infected with tuberculosis, but it may cause clinical diseases only when the resistance decreases or the cell-mediated allergic reaction increases.
Three: malaria:
Malaria is an insect-borne infectious disease, which is caused by the bite of Anopheles or the transfusion of blood from patients with plasmodium. There are four kinds of plasmodium parasitic on human body, namely Plasmodium vivax, Plasmodium vivax, Plasmodium falciparum and Plasmodium ovale.