A disease is endemic when it is always present in a particular population or region, at a fairly constant, expected level. Malaria is endemic in much of sub-Saharan Africa and parts of Asia and South America. Chickenpox is endemic in the UK.Compare these terms:
• epidemic: a sudden rise in cases well above the expected level in one area or population
• pandemic: an epidemic that spreads across several countries or continents, such as the 2009 H1N1 flu pandemic or COVID-19.Malaria is endemic where conditions suit both the parasite and the vector:
• warm temperatures; below about 18 °C P. falciparum cannot complete its development in the mosquito, so malaria is rare at high altitude
• high rainfall and standing water where Anopheles can breed
• poverty, housing without screens, and limited access to health care and drugs.In endemic areas, adults who have survived many infections have partial immunity, so most deaths are among young children and pregnant women. Travellers and people moving from non-endemic areas have no immunity and are at high risk.Health workers compare regions using incidence, the number of new cases in a time period per unit of population.Worked example: a district of 250 000 people records 45 000 new malaria cases in a year.incidence = 45 000 ÷ 250 000 × 1000 = 180 cases per 1000 people per year
• epidemic: a sudden rise in cases well above the expected level in one area or population
• pandemic: an epidemic that spreads across several countries or continents, such as the 2009 H1N1 flu pandemic or COVID-19.Malaria is endemic where conditions suit both the parasite and the vector:
• warm temperatures; below about 18 °C P. falciparum cannot complete its development in the mosquito, so malaria is rare at high altitude
• high rainfall and standing water where Anopheles can breed
• poverty, housing without screens, and limited access to health care and drugs.In endemic areas, adults who have survived many infections have partial immunity, so most deaths are among young children and pregnant women. Travellers and people moving from non-endemic areas have no immunity and are at high risk.Health workers compare regions using incidence, the number of new cases in a time period per unit of population.Worked example: a district of 250 000 people records 45 000 new malaria cases in a year.