[The malaria situation in the WHO eastern Mediterranean region]. / Maliariinaia situatsiia v regione VOZ Vostochnogo Sredizemnomor'ia.

About 45% of the population of the Eastern Mediterranean Region live under the risk of both falciparum and vivax malaria, and additional 15% under the risk of P. vivax alone. The estimated annual number of malaria cases is about 14 million, out of which 95% occur in four countries: Afghanistan, Somalia, Sudan and Yemen. In Afghanistan malaria is endemic throughout the country at altitude below 1500 m. About 80-90% of malaria cases belong to P. vivax, the rest to P. falciparum (the latter is prevalent mostly in the South and in Badakhshan). In Islamic Republic of Iran 16% of the population live in initially non-malarious areas, 66% in areas freed from malaria, 12% in areas with sporadic transmission, mostly of P. vivax, and only 6% in areas of continuous transmission with a high proportion of P. falciparum. As much as 77% of the recorded cases belong to the latter territories. Iraq. After the Gulf war, the situation deteriorated in the three north-eastern governorates, and malaria spread outside this area and rooted in the south (Basra). Syria. Transmission of P. vivax still occurs, mostly along the western part of the border with Turkey and in the north-eastern corner of the country. At present, there are three areas that causes concern along borders between the European and Eastern Mediterranean Regions: Afghanistan is a source of importation of malaria to all its neighbours; areas on the borders between Iran, Azerbaijan and, to some extent, Armenia; 4 northern governorates of Iraq and parts of southeastern Turkey, with repercussions in Syria and, to a Lesser extent in Iran, along its western border. To some extent, Cyprus is also threatened, since importation of malaria to the northern part of the island from Turkey has been documented. In practical terms, there is a need for co-ordination of antivectorial activities and standardization of control methods between the countries with strong programmes and relatively intense transmission in border areas, i.e. between Iran, and Azerbaijan, Iraq and Turkey, Syria and Turkey.

Parasitological profile of the surveyed population for malaria in an endemic area in Faiyoum Governorate, Egypt.

Egypt represents the only focus in the Mediterranean region where Plasmodium falciparum transmission still occurs. A longitudinal parasitological study has been implemented (September 1995 to December 1996) in Faiyoum, Egypt. A total of 9065 blood slides for malaria parasites were taken from all people in the study area as mass blood examination (MBE); those attending the malaria unit as passive case detection (PCD) as well as from neighborhood of the detected cases (NOD). They were stained by Giemsa stain and examined under standard conditions for positivity, parasite species and parasite density. Our results show that MBE detected 61.5% of malaria cases while 23.1% and 15.4% of the confirmed cases were detected through PCD and NOD respectively. The overall parasite rate was 5.7/1000 examined population. P. falciparum was the most predominant species (96.1%), followed by P. vivax (3.9%). The epidemiological factors causing the persistence of malaria transmission in the study area are discussed.

Studies on malaria transmission in Orissa State, India 1981 through 1986. II: Observations on the Anopheles fauna.

A general presentation is made of data derived from systematic trend studies on the Anopheles fauna in 12 study villages of Orissa State, India. Adult and larval species prevalences, seasonal densities of prominent anophelines and predilections of various species to feed on human blood are discussed and demonstrated.

Studies on malaria transmission in Orissa state: Part I. Development of a methodology for systematic studies.

Standardized collections of Anopheles were conducted by three Entomology Field Investigation Units (FIU's) working in three distinctively different areas of Orissa State. The FIU's conducted identical routine weekly work schedules in each of 12 mesoendemic or hyperendemic study villages every month. In addition, monthly house-to-house fever case surveys were conducted in each study village and biannual malariometric surveys were carried out with the timing being shifted, so that eventually all seasons were included. Such complete, extensive and meticulous entomological and epidemiological data have not been obtained earlier from this area. In fact, until the present longitudinal data became available, it was necessary to rely upon information which was gathered some 40 years ago, when environmental conditions were substantially different. The ensuing article describes the methodology that was employed to establish these systematic studies.

Population studies of Plasmodium vivax. 1. The theory of polymorphism of sporozoites and epidemiological phenomena of tertian malaria.

The understanding of clinico-epidemiological phenomena of tertian malaria has been the subject of controversy. The authors suggest a system of postulates which give a non-contradictory explanation of the phenomena of relapses and long incubation. The main idea is that the duration of exoerythrocytic development of Plasmodium vivax is a polymorphic characteristic controlled by a set of genes. According to these postulates sporozoites may be subdivided into two groups designated as tachysporozoites and bradysporozoites, responsible for early and late manifestations, respectively. The logical analysis of the system suggests that it does not contradict the experimental facts. Moreover, the theory of polymorphic sporozoites permits an explanation and quantification of interrelations between different phenomena. The authors stress that the variation of genes is much greater in natural populations of parasites than in individual isolates and strains and therefore that the features of strains do not fully reflect the features of populations. Classical laboratory experiments should be combined with epidemiological experiments which allow a study of the population as a whole. The methodology of experiments to be undertaken in further investigations of the long latency period is discussed.

Population studies of Plasmodium vivax. 2. Distribution of manifestations in foci of tertian malaria.

The authors investigate a mathematical model based on the theory they proposed in a previous publication. The model fits field data collected in re-established foci of tertian malaria. The patterns of distribution of manifestations of tertian malaria among the population may readily be explained on the basis of the theory of polymorphism of sporozoites.

An analysis of the geographical distribution of Plasmodium ovale.

For a long time Plasmodium ovale was considered a very rare causal agent of malaria, but recently it has been shown to be a fairly common parasite in Africa. The authors analyse all the findings of P. ovale outside tropical Africa and describe its distribution. This species is distributed in 2 areas, the first confined to tropical Africa and the second to islands in the Western Pacific. The authors make a medico-geographical analysis of the distribution of P. ovale, and attempt to explain particular features of it.