Kala-azar in Portugal. I. Attempts to find a wild reservoir.

Kala-azar is now increasing in Portugal where it has been known since 1910. The natural region studied is made up of the western basins of the Tejo and Sado rivers with their important estuaries and the area south of Lisbon. The climate and vegetation are mainly of the mediterranean type. Kala-azar has always been endemic in the sub-region southwest of Lisbon (45 cases from 1961 to 1978). In the Setubal peninsula the disease has always had a low incidence (10 cases from 1961 to 1978). The Alcácer do Sal subregion was, in the past, the second most active endemic zones in the country although after 1950 there was a sudden fall in prevalence (only two cases reported from 1961 to 1978). In this natural region foxes (Vulpes vulpes silacea Miller, 1907) are abundant. One-hundred and ninety-eight foxes, mostly from the Alcácer do Sal region, were killed and studied using direct examination of spleen and liver, culture in NNN of spleen and bone-marrow, hamster inoculation of spleen and IFAT of serum. All the examinations were negative for Leishmania, while Hepatozoon was found in 40.6% of the foxes and filaria in 11.9%. In spite of some shortcomings of the study methods it is suggested that they may not be an autonomous sylvatic cycle of kala-azar. The negativity of the results, lack of any sporadic cases in rural people and absence of the characteristics of a natural reservoir in the foxes, all seem to point to such a conclusion.