Various clinical types of Q-fever disease.

Q-fever is the generic name for infections mainly occurring as respiratory tract infections with Coxiella burnetii, a obligate intracellular infectious agent belonging to Coxiella genus which is a near relation of Rickettsia family, and its most common type of disease is respiratory infections such as pneumonia and bronchitis. Q-fever has the mortality of 1 to 2%, which is a self-limiting disease and a frequently occurring common disease of relatively good prognosis, but it has been less recognized in clinical practice especially in Japan. The first report of Q-fever is the outbreak occurring at the slaughterhouse in Brisbane, Australia in 1935 (1), and its pathogen was discovered in 1937 (2). In Japan, the report in 1989 was the first spontaneous infection except for the case infected in the laboratory (3). In Western countries in 1990's, it was shown by many reports that this bacteria accounted for the fourth or fifth rank of frequency next to Chlamydia pneumoniae as a causative pathogen of community-acquired pneumonia (4). However, there are types of disease, including hepatitis and fever unknown origin, other than respiratory infections, and it has been shown that there are various problems and some cases show persistent or chronic progress and there are unclear relationships among the types of diseases. In addition, it has been said that, even if infections are established, only about one half of them develop diseases and the rest remain as latent infections. Table 1 summarizes various types of Q-fever disease observed to date. The most common Q-fever is the acute one, which shows flu-like symptoms and acute upper respiratory tract infections such as the common cold. There are many cases showing a form of mycoplasma pneumonia and atypi-cal pneumonia similar to chlamydial pneumonia or Legionella pneumonia, but there are also many cases showing a form of acute hepatitis marked by hepatic dysfunction only. In addition, there are many cases preoccupied with fever of unknown origin, but there are not many cases with encephalitis or meningitis. The diagnosis is determined by confirming a significant increase in the serum antibody titer to Q-fever Coxiella in the time-course determination, but no quick diagnosis has been established, which is an issue to be resolved. Regarding treatment, tetracyclines, macrolides and quinolones of good migration into cells are effective, but since Q-fever is a self-limiting disease, it is considered that there are many spontaneously healed cases showing apparent improvement in spite of the …