Human Diseases, Pathogens & Epidemiology
Pathological conditions in humans are classified into communicable infectious diseases caused by pathogens (viruses, bacteria, protozoa, fungi, helminths) and non-communicable lifestyle disorders. Bacterial diseases include tuberculosis (caused by Mycobacterium tuberculosis), typhoid (Salmonella typhi, confirmed via the Widal test), and cholera (Vibrio cholerae). Viral infections include influenza, rabies, hepatitis, dengue, and HIV/AIDS, which attacks CD4+ T-lymphocytes. Vector-borne protozoan illnesses include malaria, caused by Plasmodium parasites transmitted by female Anopheles mosquitoes. Non-communicable diseases—including cardiovascular conditions, hypertension, type 2 diabetes mellitus, and cancer—constitute the leading causes of global mortality, monitored through public health surveillance frameworks.
Key Concepts & Examination Highlights
- Malaria is caused by the protozoan parasite Plasmodium and is transmitted to humans through the bite of an infected female Anopheles mosquito.
- The Widal test is the standard serological diagnostic test used to detect enteric fever caused by Salmonella typhi (Typhoid).
- Tuberculosis is caused by the acid-fast bacterium Mycobacterium tuberculosis, primarily affecting pulmonary lung tissue.