G. Sabatinelli, M. Ejov, P. Joergensen
WHO EURO, Copenhagen, Denmark

The number of autochthonous reported cases of malaria fell from 90 506 to 37 170 between 1996 and 1999 in the WHO European Region. There has been, however, an eight-fold increase in imported cases since the 1970s: 1500 cases were reported in 1972, 13 000 cases in 1999. France, Germany, Italy, and the United Kingdom are the west European countries with the largest numbers of cases.

Introduction

A campaign launched at the end of the 1950s eradicated malaria in all countries in the World Health Organization (WHO) European Region, with the exception of the Asian part of Turkey and some residual foci in Azerbaijan and Tajikistan. By the 1980s, malaria was an almost forgotten disease in the European Region, but in recent years it has dramatically re-emerged as a result of political and economic instability, massive population movements, and changes in land use (1, 2).

Another substantial problem in the European Region are cases of malaria imported from endemic tropical countries (2). The continual increase in international travel (communication from the World Tourist Organization, 1998) and population movements have led to a massive import of communicable diseases into countries where they had been eradicated (3). Coinciding with the development of resistance to drugs used for the treatment and prophylaxis of malaria, the risk of plasmodium species being imported into areas that are receptive to malaria is increasing (4).

This paper presents the malaria situation in the member states of the WHO European Region over the past 30 years.

WHO monitoring system

The 51 countries in the WHO European Region (EURO) are located in an area corresponding geographically to Europe, Anatolia, the Caucasus (Georgia, Armenia, Azerbaijan), Siberia, and central Asia (Kazakhstan, Kyrgyzstan, Tajikistan, Uzbekistan). This area corresponds to north Eurasian and Mediterranean malaria epidemiological areas.

These 51 countries are asked every year to provide information on the number of laboratory confirmed cases of malaria registered. The Roll Back Malaria EURO programme maintains a database on five main epidemiological indicators: the total number of malaria cases, the number of autochthonous endemic malaria cases, the number of imported cases of malaria, the number of cases with Plasmodium falciparum malaria, and the number of deaths. All this information is available for the years since 1971 and is searchable on the web at http://cisid.who.dk/mal.

Since 1997, for imported cases the countries have been required to provide information by country where the infection was acquired, by plasmodia species, by sex, by standard age groups, and by profession. Almost all countries of the region now provide complete information in a reasonable time limit.

Autochthonous malaria

Since the early 1990s, the malaria situation has deteriorated considerably in some of the countries of the WHO European Region, owing to political and economic instability, massive population movements, and large scale hydro-agricultural projects.

In recent years, Azerbaijan, Tajikistan, and Turkey have had massive epidemics, whereas Armenia, Turkmenistan, and Georgia experienced small outbreaks. Sporadic cases of endemic malaria were also reported in Kazakhstan, Kyrgyzstan, the Russian Federation, Uzbekistan, Moldova, Bulgaria, Greece, and Italy. In 1995, a total of 90 712 cases of endemic malaria were reported in the region (table). In 1996-1999, the reported number of cases declined from about 90 506 to 37 170, and it is expected that the malaria cases will slightly increase to about 42 000 in 2000.

Table. Number of autochthonous malaria cases registered in the countries of WHO European Region (the other 37 countries did not register any case)

Despite a noticeable reduction in the reported incidence of malaria in the region, the situation is currently complicated by transmission of P. falciparum in Tajikistan, where about 400 cases were reported in 2000, and by the spread of transmission to the northern and other parts of Tajikistan. The risk of a massive re-establishment of transmission is comparatively high in some areas of Uzbekistan, Turkmenistan, Georgia, Kyrgyzstan, and Kazakhstan that border countries where malaria is epidemic. This is particularly due to their high receptivity (favourable conditions for malaria transmission) and to the frequent introduction of malaria parasites by infected carriers.

Malaria remains a problem in Turkey, where its incidence remains high (20 905 autochthonous cases in 1999), and over 15 million people or 23% of the total population still live in areas where malaria is endemic. Almost 44% of the total population live in non-endemic areas, where the risk of a resumption of malaria transmission is high.

Imported malaria

Imported malaria is a growing medical and health issue in Europe, and mortality from malaria presents a challenge to the medical profession there.

Since the early 1970s there has been an eightfold increase in the number of imported cases, from about 1 500 cases in 1972 to 13 000 in 1999. In 1972-83 the number of cases increased steadily, but from 1983 to 1985 it practically doubled, and this explosive growth continued up to 1989, when almost 12 000 cases were reported. In the period that followed, the number of malaria cases declined until 1992 when it once more increased and reached 13 037 in 1998—the highest number registered in the period.

Most of the cases of malaria imported into WHO's European Region are imported into the western part of Europe, especially into member states of the European Union (EU) (figure 1). The largest numbers of cases have been recorded in France (5 940 in 1998), the United Kingdom (2 500 in 1996), Germany (1 021 in 1997), and Italy (1 006 in 1999). Together these countries account for almost 75% of all imported cases of malaria in the WHO European Region in 1999.

From 1971 to 1999 the ratio between P. falciparum and other plasmodium species changed. From the 1970s until the early 1980s the proportion of cases with P. falciparum malaria constituted less than 30% in average. Between 1984 and 1987, however, the ratio of imported cases of P. falciparum infection compared with other plasmodia began to increase steadily when the proportion of P. falciparum cases increased to almost 70%, a level at which it remains . This is due to the fact that P. falciparum is largely prevalent in Africa, and currently more than 80% of the imported malaria infections acquired by European travellers are acquired in Africa, more specifically in the western and central parts of the continent.

In the past 10 years (1989–99), 680 people died from infection with P. falciparum in the WHO European Region. On the basis of the number of P. falciparum cases and number of deaths, the average case fatality rate was calculated for the region (only countries for which data both on deaths and on P. falciparum cases were available in the same year were included).

As indicated in figure 2, the number of deaths increased in the beginning of the 1980s concurrently with the sharp increase in the number of cases of P. falciparum malaria. In the same period the yearly case fatality rate decreased from more than four to one to two. These rates seem to be higher than the fatality rate registered in endemic countries (7). People living in non-endemic countries are at higher risk of death once they are infected. Although the immunity status is playing a part, the main discriminating risk factor identified by some studies is the delay in seeking medical care in specialised centres (5, 6).

Conclusion

The situation of malaria in the WHO European Region present a complex epidemiological picture that is characterised by:

• the variation in malaria endemicity levels in Turkey;
• the resurgence of malaria in the newly independent states (NIS) of the Caucasus and central Asia; and
• imported malaria cases from tropical and subtropical endemic countries.

Different determinants influence each context.

Malaria endemicity levels in Turkey

The explosive malaria epidemic in Turkey in recent years has caused a dramatic emergency situation and affected the socioeconomic development in the south eastern part of the country. The situation is conditioned by many factors arising from historical presence of fertile but marshy soils in the Seyan plains and irrigation of arid territories in Urfa district. The complex ecological situation resulting from rapid agroindustrial developments that attracted numbers of people from less developed and still malarious areas and simultaneously increased the vector densities. This created the basis for epidemic development. The inability of the public health infrastructure to keep abreast of this particular situation allowed the uncontrolled spread of the epidemic. This sudden resurgence of malaria has shown that malaria epidemics may spread in a country in the future, if no preparations have been made to combat malaria epidemics.

Resurgence of malaria in the newly independent states

Unfortunately the recent political, social, and economic events in the newly independent states have had a negative impact on the malaria situation. All the NIS in central Asia and the Caucasus experienced considerable problems in preventing and controlling malaria in the 1990s. The disruption of traditional links between the former republics of the Soviet Union has resulted in difficult economic conditions, massive human migration, and a sudden reduction in the access and quality of health care. All these factors have resulted in a dramatic reduction in access to primary health care and an inability to respond to changes in the epidemiology of malaria in the most southern states. The epidemic in Afghanistan (2 - 3 million estimated cases, WHO 1998) played a particularly important part in the spread of malaria in central Asia, through the military troops employed as peacekeepers along the border with Tajikistan. Massive population movements within countries as well as crossborder migrations, including infected people, have introduced malaria into areas that were previously free of the disease while the potential breeding places for malaria vectors have broadened owing to poor maintenance of irrigation systems.

Imported malaria cases from endemic tropical and subtropical countries

In the past decade, the number of malaria cases imported into Europe has steadily increased, mainly because of:

• the constant increase in the number of foreigners, from countries with endemic malaria, who have immigrated into European countries;
• the growing number of intercontinental passengers visiting tropical and subtropical areas mainly for tourism;
• the development of multiresistance to drugs used for the treatment and prophylaxis of malaria; and
• the increase in the levels of endemicity of malaria worldwide particularly in Africa.

Although it is evident that there is a positive correlation between the increase in the number of cases of imported malaria and an increase in travel it has not been possible to verify the correlation statistically because the travel statistics are incomplete.

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