Malaria situation in Bulgaria and surveillance measures (1991-2000)

The malaria situation in Bulgaria during the past decade of the century was analysed and the evaluation
of the risk of re-emerging of the diseases and factors determining it in the phase of maintanence
of malaria eradication was carried out. The epidemiological analysis of malaria cases notified during
the period 1991-2000 in Bulgaria is presented. Of a total of 382 malaria episodes registered, 363
(95.03%), were imported into Bulgaria from endemic countries, 1 (0.26%) occurred after haemotransfusion
and 18 (4.71%) were indigenous introduced ones. Plasmodium falciparum accounted for 68.59%
of all imported cases, P.vivax, for 23.82%, P.ovale, for 2.36%, P.malariae, for 1.85%. In 1.83% more
than one species was detected, and in 6 cases, the species was not identified. The import of malaria
came mainly from Africa-299 (82.37%) cases, followed by Asia-63 (17.36%) and Oceania-1 (0.27%).
Four cases with falciparum malaria resulted in death. A great number of imported cases-231 (63.81%)
was diagnosed during the potential malaria season in Bulgaria (April-October). The analysis of present
entomological situation showed a high density of Anopheles population. As an indication for existence
of potential risk of spread of indigenous malaria, especially in cases of delayed diagnosis and treatment,
18 indigenous cases of vivax malaria were recorded in 1995-1996 in the region of the town of Sandanski,
for the first time after malaria eradication in 1965. The cases were classified as introduced ones. The
analysis of the essential malaria import in Bulgaria, climatic conditions and presence of Anopheline
species revealed a fairly high level of malariogenic potential. The stratification of the country was carried
out in accordance with the degree of hazard of malaria spreading, and the territory was divided
into three categories of regions: with high-, medium- and low-risk. The present situation, that probably
will be valid for the future, too, requires a scientific based prognosis and improvement of a system of
surveillance activities aiming at prevention of indigenous endemic and epidemic spreading of malaria
in the country, as well as elaboration of adequate activities of the health network in case of reappearance
of autochthonous cases.