Answer: Typhoid fever.
- A Malaria
- B Typhoid fever
- C Dengue
- D Tuberculosis
Correct answer: B. Typhoid fever
Explanation: The Widal test detects antibodies against Salmonella typhi antigens (O and H antigens) in patient's serum. It is a diagnostic test for typhoid fever. A rising titre (4x increase) over two tests is diagnostic.
The Plasmodium parasite needs both hosts: the female Anopheles mosquito injects sporozoites while biting (infecting the human liver and RBCs, causing the malaria fever cycle), then picks up gametocytes from an infected person's blood, completing the parasite's sexual stage inside the mosquito.
Concept context
Pathogens, infectious diseases, non-infectious diseases, drugs, cancer, and public health. High NEET importance.