Epidemiological classification - stable versus unstable malaria

There is no completely satisfactory epidemiological classification of malaria. Stable malaria means that the clinical disease is characterised by preferentially affecting children and achieving a protective "immunity" in adults. Stability does not mean that there can be no variation in transmission. In some regions seasonal malaria occurs. In other areas there is unstable malaria: transmission differs greatly from year to year and sometimes epidemics occur. The disease then also occurs in older persons. This is important in many respects, including the fact that irregular control of malaria may lead to changes in the immune status of the population. Sometimes malaria may appear again in a region. For example: in 1972 the disease was eradicated in South Korea following an intensive eradication campaign with case detection and vector control. In 1993 one case of P. vivax was observed. There then followed 22 cases in 1994, in 1995 there were 107 cases, 356 in 1996 and more than 1600 in 1997. In 1995 all cases were still limited to the border area with North Korea, but in 1996 there was also transmission outside the demilitarised zone. After entomological surveys had shown that Anopheles sinensis was the chief vector, measures were taken to control the disease.

Category: Medicine Notes