**Question:** True about epidemiology of malaria -

A. Malaria is endemic in tropical and subtropical regions
B. Malaria is a disease caused by a single bacterium
C. Malaria cases have significantly decreased in the last decade
D. Malaria is primarily found in developed countries

**Correct Answer:**

A. Malaria is endemic in tropical and subtropical regions

**Core Concept:** Malaria is a mosquito-borne infectious disease caused by protozoan parasites of the Plasmodium genus, predominantly affecting humans. It thrives in warm, humid climates where the malaria-carrying Anopheles mosquitoes are present.

**Why the Correct Answer is Right:** Malaria is predominantly found in tropical and subtropical regions due to the optimal environmental conditions for the development and reproduction of the Plasmodium parasites and their vectors, Anopheles mosquitoes. These regions have warm temperatures, high humidity, and rainfall, which provide suitable conditions for mosquito breeding and parasite development.

**Why Each Wrong Option is Incorrect:**

B. Malaria is caused by a single bacterium (Bacteria): Malaria is caused by Plasmodium parasites, not bacteria. It is transmitted to humans via the bite of infected Anopheles mosquitoes.

C. Malaria cases have significantly decreased in the last decade (incorrect statement): Malaria remains a major global public health concern, with around 229 million cases and 409,000 deaths estimated in 2020 alone (World Health Organization, 2021). While efforts to control and eradicate malaria are ongoing, the actual situation may vary across regions and countries.

D. Malaria is primarily found in developed countries (incorrect statement): Malaria is prevalent in developing countries with inadequate healthcare systems and infrastructure. Developed countries have implemented preventive measures and control programs, reducing the risk and prevalence of malaria.

**Clinical Pearl:** Understanding the epidemiology of malaria is crucial for healthcare professionals to accurately diagnose, treat, and prevent the disease. Knowledge of the disease's distribution helps in formulating prevention and control measures, promoting targeted interventions, and educating the public.