[Seroprevalence of anti-hepatitis A antibodies in Czech soldiers serving in U.N. forces--suggestions for a hepatitis A vaccination schedule].

Viral hepatitis A is a frequent disease particularly in developing countries. All workers and UN forces (UNO) are vaccinated against VHA with Havrix vaccine. The Czech units which were and are engaged on the territory of former Jugoslavia are not yet vaccinated against this contagious disease. The main purpose of the present study was to assess the immunity rate of VHA among Czech soldiers of the UN forces before their departure to the site of action. Another objective was to assess a suitable vaccination procedure. Sera were examined by the MEIA method (Microparticle Enzyme Immunoassay) in a fully automated IMx system in the Military Health Institute, Ceské Budĕjovice. For investigation HAVAB kits of Abbott Co. were used. A total of 667 serum samples were assembled, 19 had to be discarded because of small amounts (less than 50 microliters or because of haemolysis. The positive titre of "total" antibodies was set at 35 mIU anti-HAV; thus a total of 648 specimens were examined in 1991 - 1994 (1991 - 65, 1992 - 296, 1993 - 265, 1994 - 22). Of these 249 (38.4%) were positive and 399 (61.6%) were negative. The examined subjects were divided into four age groups (20 - 29, 30 - 39, 40 - 49, 50 - 59), the approximate distribution being 23%, 50%, 25%, 2%. The ratio of negative and positive specimens in different age groups was 1:0.3, 1:0.6, 1:1, 1:2.7. The seroprevalence of anti-HAV antibody increases from 25.3% in the first age group, in the second one it is 37.9%, in the third one 49.5% and 72.7% in the last age group, i.e. in the age bracket of 50 - 59 years. The results indicate a very low immunity rate in the lower age brackets and the necessity to vaccinate them before they depart. It is beyond doubt that it pays to examine the soldiers for the presence of total anti-HAV and immunize only subjects with a negative antibody titre. The vaccination approach Havrix 2 x 720 EU was recommended.