The Topic of This Month Vol.17 No.10 (No.200)

Genital chlamydial infection, 1993-1995, Japan

The information on sexually transmitted diseases (STD) patients is collected from about 600 sentinel clinics participating in the National Epidemiological Surveillance of Infectious Diseases (NESID) and being situated in every prefecture and designated city in the whole country. The sentinel clinics contain such specialized sections as urogenital/STD clinics (57%), obstetrics/gynecology (31%), dermatology (10%) and other fields (1.2%) (as of March 1990). STD involves five distinct diseases (see Table 1). After 1987, when collection of information on these diseases started, STD patients decreased in number during 1988-1989, increased during 1990-1991, and again have been decreasing since 1992. Of these patients, those of genital chlamydial infection tended to increase during 1987-1992, notably among females (see IASR Vol. 11, No. 9, 1990; Vol. 14, No. 8, 1993).

Reports on STD patients tended to keep decreasing during 1993-1995 (Table 1). Patients of genital chlamydial infection once decreased in 1993, but again increased in 1994; however, gonorrhea patients decreased markedly in 1994. Consequently, the ratio of patients of genital chlamydial infection to those of all STDs increased from 38% in 1992 to 44% in 1994. In 1995, patients of genital chlamydial infection slightly decreased, but those of gonorrhea increased; therefore, the ratio of cases of genital chlamydial infection to those of all STDs decreased slightly. After 1990-1992, the ratio of cases of genital chlamydial infection to those of gonorrhea kept increasing till 1994, but it decreased in 1995.

The incidence of genital chlamydial infection during 1993-1995 was reviewed and is shown in terms of yearly cases per sentinel clinic by sex and age (Table 2). The majority of patients aged 25-29 years among males and 20-24 years among females, as was the case during 1990-1992. Female patients of this age group (20-24 years) inclined to outnumber those of male patients after 1992. The sex ratio of all age groups decreased from 1.45 in 1992 to 1.26-1.29.

IASR, separately from NESID, collects information on detection of pathogenic microorganisms from the cooperating general clinical institutions in the whole country and gives it in a tabular form (no information is given on sex or age of cases). Reports on detection of Chlamydia trachomatis from genitourinary sources numbered 1,747-1,871 during 1993-1995, being slightly less than 1,984 in 1992. On the other hand, those of Neisseria gonorrhoeae tended to decrease after 1992, but increased in 1995 in line with the trend pointed out by NESID (Table 3).

The reports on detection of Chlamydia from individual cases furnished to IASR by 11 laboratories including prefectural and municipal public health institutes (PHIs) during 1993-1995 numbered 706. The sources of detection were genitourinary in 683 cases and eye swabs in 23 cases; the methods for detection were the cell culture in 207 cases, the fluorescence antibody technique in 382 cases, and enzyme immnoassay in 174 cases (including those giving positive results by multiple methods). Of a total of 683 patients with Chlamydia detection from genitourinary sources, except four cases of unknown ages, 679 including 582 symptomatic cases with clinical diagnoses and 97 asymptomatic ones and those who were willing to take examinations are shown according to their sex and age group (Fig. 1). The majority of male cases aged 20-29 years and the percentage of asymptomatic cases in any age group was 6.9% or lower. Among female cases, the age group of 20-29 years was also predominant, but the percentage of asymptomatic cases was much higher, being 36-48%. Also of the 30-44 year group, 44-56% cases were asymptomatic.

Detection of Chlamydia from eye swabs in 23 cases was reported by two PHIs. In 18 cases, clinical diagnoses were made; all were keratoconjunctivitis. The age distribution of patients tells that the majority of male patients were in the 25-29 year group and that of female patients in such a young group as the 15-19 year one (Fig. 2).

According to NESID as of the second quarter of 1996, patients of all STDs, those of gonorrhea in particular, tend to increase, and those of genital chlamydial infection are increasing in larger cities.

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