Human Health and Diseases
Human Health and Diseases tests pathogen biology, transmission, diagnosis, immunity, AIDS, cancer and substance abuse.
Core rules
- Malaria is caused by Plasmodium species and transmitted by female Anopheles mosquitoes. Sporozoites infect liver cells, then red blood cells; gametocytes are taken up by mosquitoes.
- Typhoid is caused by Salmonella typhi and diagnosed by the Widal test; pneumonia is commonly caused by Streptococcus pneumoniae.
- HIV is a retrovirus with reverse transcriptase; it infects CD4 helper T cells and causes AIDS.
- Cancer arises from uncontrolled cell division; malignant tumours invade and metastasise.
Worked example
A patient has cyclical fever and chills after a forest visit. Malaria is suspected. The reasoning is that female Anopheles bites inject sporozoites; liver-stage multiplication is followed by RBC infection, and synchronous RBC rupture releases merozoites and pyrogens, producing periodic fever. Diagnosis uses blood smear or rapid antigen test. Mosquito control and bed nets interrupt transmission.
Traps
- Malaria is not spread by casual contact or by all mosquitoes; the vector is the female Anopheles.
- AIDS is not transmitted by mosquito bites, sharing food or casual touch.
- Benign tumours do not metastasise; malignant tumours do.
- Antibiotics treat bacterial infections, not viral infections such as common cold or AIDS.