Academic journal article Bulletin of the World Health Organization

World Malaria Situation in 1991

Academic journal article Bulletin of the World Health Organization

World Malaria Situation in 1991

Article excerpt

In 1991, 90 countries or areas were considered malarious. In nine of these, falciparum malaria does not exist or its proportion is less than 1%. For comparison, there were 140 countries or areas where malaria were considered endemic in 1955.

The total world population of about 5340 million people may be classified according to the status of malaria and their residence as follows:

-- areas, situated mainly in tropical Africa, where

endemic malaria remains basically unchanged

and most control programmes are still at a plan-

ning or early implementation state (490 million

people; 9% of world's population);

-- areas where endemic malaria was considerably

reduced or even eliminated but where transmis-

sion was reinstated and the situation is unstable

or deteriorating (1750 million people; 33%); and

-- malaria-free areas (3100 million people; 58%).

The most recent estimates indicate that the incidence of malaria in the world may be 300-500 million clinical cases each year, with countries in tropical Africa accounting for more than 90% of them.

In the great majority of countries of the WHO African Region, strict notification of cases does not exist and reporting is fragmentary. The number of cases registered is not comparable with that from other regions and is therefore not included in the total figures in Table 2. In the other regions, the total number of cases has not changed much over the last years; however, trends in the individual countries vary. Approximately 5.6 million cases were reported during 1991, but the actual number of caes is estimated to be about four-to-five times higher. Of the total number of cases reported annually to WHO (excluding the African Region), 90% come from only 19 countries. More than 70% are concentrated in seven countries (in decreasing order): India, Brazil, Sri Lanka, Afghanistan, Thailand, Viet Nam, and Colombia. India and Brazil alone account for 38% and 11% of all cases reported, respectively. Furthermore, within countries, malaria is concentrated in certain areas.


Below is presented a summary of the situation.


In Africa north of the Sahara, the total number of cases reported annually has been around 1000 during recent years.

The Libyan Arab Jamahiriya and Tunisia are considered free from malaria transmission.

In Egypt, the number of cases recorded declined from 75 in 1990 to 24 in 1991. Most of them (falciparum infections) were from a new focus in Biahmo, Sennoris District, El Faiyum Governorate. No cases were found in the previous foci of Khour Saoudi (1990) and Terssa (1989) in the same district. In Algeria, 42 local cases were reported, all vivax infections, in two foci in Ain-Defla (Arib) and Illizi (Ihrir) Wilayas. In Morocco, the number of cases detected decreased from 839 in 1990 to 494 in 1991. The situation improved in El Kelaa Sraghna and Settat Provinces. Transmission continued in the foci in Khenifra, Khouribga, Taza, Khemisset, Beni Mellal and Larache Provinces.

In Africa south of the Sahara, 12--22 million cases per year were reported over the period 1985--89. It has been estimated, however, that 270--480 million clinical malaria cases may occur every year, with about 140--280 million of these occurring in children less than 5 years of age. Africa has the highest levels of endemicity, with very large areas classified as holoendemic (in forest or savannah at altitudes up to 1000 m with an average rainfall 2000 mm/year). At altitudes >1500 m and rainfall <1000 mm/year, endemicity decreases and the potential for epidemic outbreaks increases. Ecological, demographical and meteorological factors including quasi-cyclic occurence of heavy rains have led to epidemics or serious exacerbations of endemicity (Botswana, Burundi, Ethiopia, Kenya, Madagascar, Rwanda, Swaziland, Sudan, Zaire and Zambia). …

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