A serological investigation wm conducted in Tunisia to obtain preliminary information on the arboviruses that might be present among the population. Altogether 1406 serum samples were drawn, 1094 of them from persons living on the island of Djerba; all but 36 of the total sera were from children of school age. The haemagglutination-inhibition test was used for most sera, but serum neutralisation tests were also perfomed on 25 sera and complement-fixation tests on 170. Seven antigens representative of the more important arboviruses isolated in the Mediterraneml area were usedÑnamely, Sindbis, chikungunya, West Nile, Japanese encephalitis, Central European tick borne encephalitis, Sicilian sandfy fever and Tahyna.
It was shown that arbovirus infections are present among the Tunisian population, some 5 % of the total sera tested containing antibodies to one or more of the antigens. The highest proportions of antibody were to West Nile (4.7 %) and Sicilian sandfly fever (2.5 %); rather few sera were positive for Central European tick-borne encephalitis and Japanese encephalitis (0.5% each) or to Sindbis (0.2 %), and none to chikungunya or Tahyna.
The authors point out that, since birds are known to be important in the West Nile and Sindbis virus cycles and may play a role in the transcontinental transmission of other arboviruses and since Tunisia is on the spring and autumn bird-migration route between Europe and Africa and also serves as an important wintering territory, a variety of arboviruses already known from other countries elsewhere in the Mediterranean area may well be endemic in Tunisia.