Communicable and Non-Communicable Diseases
This section covers communicable and non-communicable diseases. The exam tests the distinction, modes of transmission, common examples, risk factors and prevention.
Communicable diseases
These are caused by pathogens and can spread between people, animals or through vectors and contaminated food or water. Examples include tuberculosis, caused by Mycobacterium tuberculosis and spread by airborne droplets; malaria, caused by Plasmodium and spread by female Anopheles mosquitoes; dengue, caused by dengue virus and spread by Aedes aegypti; typhoid, spread by contaminated food or water; HIV, spread through blood, sexual contact and mother-to-child transmission; and COVID-19, spread mainly by respiratory droplets and aerosols.
Non-communicable diseases
These are not transmitted from person to person. Major examples are type 2 diabetes, hypertension, cardiovascular disease, cancer, obesity and asthma. Risk factors include tobacco, alcohol, unhealthy diet, physical inactivity, obesity, raised blood pressure and genetics.
Prevention
Communicable disease control uses immunisation, safe water, food hygiene, handwashing, vector control, ventilation and isolation when needed. Non-communicable disease control uses screening, balanced diet, regular exercise, tobacco control and adherence to treatment.
Worked example
A person has fever, chills and an enlarged spleen after mosquito bites in a malaria-endemic area. Reasoning: the vector and symptoms point to malaria. It is communicable in the sense of being transmitted by a vector, but it is not spread directly from person to person. Prevention focuses on nets, repellents and eliminating standing water, not on isolating the patient.
Traps
Do not say malaria spreads by casual contact. Do not call all non-communicable diseases non-infectious in every context. Do not confuse dengue and malaria vectors. Do not reduce prevention to medication alone.