Introduction

The comprehensive data available for Estonia, Latvia, and Lithuania begin from the Soviet period (postSecond World War), the pre-war data about parasitic infections being fragmentary. We will thus, in this review, concentrate on the period beginning from the end of the 1940s to the present. The helminth fauna of the three Baltic states localized in the temperate climate zone is represented mainly by parasites of animals. Humans are hosts for eight main local helminthosis: two geohelminthosis [ascariosis due to A. lumbricoides, and trichiuriosis due to T. trichiurus (also known as Trichuris trichiura)], four biohelminthosis [taeniosis due to T. solium and Taeniarhynchus saginatus

(also known as Taenia saginata)], diphyllobothriosis due to D. latum, and trichinellosis due to Trichinella spiralis), and two contact helminthosis (hymenolepiosis due to Hymenolepis nana, and enterobiosis due to Enterobius vermicularis).

In the end of the 1940s and during the 1950s, helminthosis screening and control programmes were introduced in the territory of all Baltic states of the former Soviet Union. From the 1960s to the end of the 1980s, between 30 and 50% of the total population in all

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three countries was tested yearly for helminth eggs by coprological analysis or perianal scrapings. For instance, in 1949 in Lithuania only 17103 persons were tested for helminthosis. The following year the number was already 76572 and the number of people tested increased every year reaching about 1.5 million in the 1970s. The largest number of people were screened at the end of the 1980s, reaching 1.85 million in 1988 in Lithuania and more than 1.5 million in Latvia in 1986, constituting about 60% of the population. The individuals tested positive for helminths were treated free of charge. So for instance in Lithuania every fourth (520096) person was tested for helminths and every eighth was dehelminthized in 1955 (Biziulevicius, 1958). After restoration of independence of the Baltic states in 1991, the proportion of the population screened has declined to 15-30%.

The statistics of parasitoses from the three Baltic states embrace mostly the eight helminthoses mentioned earlier, so these form the main theme of the current review, supplemented with a brief overview of the data available about other parasites.

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