12.1  What is a malaria epidemic?

An epidemic, in general, is defined as the occurrence of cases in excess of the number expected in a given place and time period. Malaria epidemics are defined in this way.

In some places, malaria transmission increases after the rainy season and then decreases during the dry season every year. If this is what normally occurs in your village, then an abnormal increase above this normally expected seasonal variation is considered an epidemic.

  • Imagine that your village is in an area where there is no malaria. How many malaria cases would be expected? Giving reasons, say how many malaria cases would have to occur in your village for an epidemic to be recognised?

  • Zero malaria cases would be expected. If even one case of malaria occurs in the village, then this would be recognised as a malaria epidemic, because it is more than the number that would be expected in this village.

In order to know whether there is malaria in the village you are working in, look at the patient register in your Health Post and see if there are malaria cases for the past three to five years. If there are malaria cases, and the patients had no travel history to a malarious area prior to their infection, then your village is in a malarious area. If there are no malaria cases for these years, then your village is malaria-free.

Learning Outcomes for Study Session 12

12.2  Factors that trigger epidemics