Malaria
Explanation
Infectious diseases in humans are classified based on the nature of the causative agent (pathogen). These agents include bacteria, viruses, protozoa, fungi, and helminths. Identifying the specific category of the pathogen is essential for understanding the disease's pathology and treatment.
Option Analysis
- Typhoid is incorrect: Typhoid fever is a bacterial disease caused by the bacterium Salmonella typhi. It typically spreads through contaminated food and water.
- Tuberculosis is incorrect: Tuberculosis (TB) is a bacterial infection caused by the bacterium Mycobacterium tuberculosis. It primarily affects the lungs but can spread to other parts of the body.
- Malaria is correct: Malaria is caused by a protozoan parasite belonging to the genus Plasmodium (e.g., P. vivax, P. falciparum). The parasite is transmitted to humans through the bite of an infected female Anopheles mosquito.
- Chickenpox is incorrect: Chickenpox is a viral disease caused by the Varicella-zoster virus (VZV). It is highly contagious and characterized by a skin rash.
Key Takeaway: Malaria is a vector-borne disease caused by a protozoan parasite, whereas Typhoid and Tuberculosis are bacterial infections, and Chickenpox is a viral infection.