A Study on Inapparent Infection of Scrub Typhus in Japan

III. Serological survey of mild febrile diseases on inapparent infection of scrub typhus

Abstract

For the purpose of finding the inapparent infection of scrub typhus among sporadic cases of mild febrile diseases of which causes are unknown, the following serological surveys were carried out.
1) Twelve sporadic cases of mild febrile disease were reported at Yanai, Yamaguchi Prefecture during the season from November, 1960 to March, 1961. Among the 12 cases, 11 were positive in CFT against Karp antigen of scrub typnus. Furthermore, one of the 4 healthy inhabitants investigated was positive. The Clinical symptoms of these patients were, however, quite different from those of the scrub typhus, so that the confirmation of the inapparent infection of scrub typhus could not be done.
2) An outbreak of a febrile disease with rash was reported in infantrymen of the Japanese Self-Defence Forces at Nayoro, Hokkaido. Only one case showed a positive reaction in a low titer against Gilliam antigen in CFT, suggesting a possibibility of inapparent infection with Gilliam type of scrub typhus in Hokkaido.
3) A case of scrub typhus was reported among a group of infantrymen at Kijima highhill, Oita Prefecture. However, no inapparent infection was proved by serological survey using CFT among the group which took part in the manuever with the patient.