Infectious diseases are caused by external pathogenic agents such as viruses, bacteria, and other microbes. These agents enter the body, where they begin to multiply and spread. The disease develops when these microorganisms cause damage to the body’s cells and tissues, triggering an inflammatory response and a range of symptoms that affect the individual’s overall health. The interaction between the pathogen and the host’s immune system determines the severity and progression of the infection.
Recent reports from the World Health Organization (WHO) rank infectious diseases among the top 10 causes of mortality in low-income countries. Among the most prevalent infectious diseases are AIDS (caused by the HIV virus), tuberculosis, and hepatitis B and C.
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