Prevalence of Salmonella agglutinins among the population of a non-epidemic and an epidemic area in south-western Finland.

Although very few of the salmonellae are encountered in Finland, epidemics of salmonellosis are not infrequent. The purpose of the study reported in this paper was to establish to what extent the Widal reaction might facilitate the diagnosis of typhoid and enteric fever.Sera were collected in two areas of south-western Finland: from the population of a non-epidemic area, and from that of an epidemic area during an epidemic and two years later.In the non-epidemic area, Salmonella agglutinins were rarely encountered, but they were abundant in the epidemic area, as expected. Two years after the epidemic, only slightly raised O agglutinin titres were observed. In persons vaccinated at least 12 months before the start of the study, the O agglutinin titre was not increased, but H agglutinins were found in high titre 11-15 years after vaccination.The author concludes that the Widal reaction may be of considerable diagnostic assistance, particularly in the light of the patient's past history of Salmonella infection and prophylaxis and of his place of residence. Even in the absence of information on these factors, the occurrence of O agglutinins is of diagnostic importance.