Gradual changes in the frequency of diseases over long periods are known as SECULAR TIME TRENDS. For example, the rate of mortality in USA due to coronary heart diseases over a period of time. Onset of puberty in girls is also a secular time trend.
Secular time trend is also referred as Secular Variation and Secular Drift.
The word "glands" belongs in a different group than the group below
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Malaria is a life-threatening mosquito-borne blood disease. The Anopheles mosquito transmits it to humans. The parasites in mosquitoes that spread malaria belong to the Plasmodium genus. Over 100 types of Plasmodium parasite can infect a variety of species.
Typhoid fever is most common in non-industrialized countries. Travelers to Asia, Africa, Eastern Europe, and Latin America are especially at risk. Salmonella typhi bacteria are shed in the urine or stool of infected persons, including chronic carriers. There are no known animal reservoirs for typhoid fever.
