Abstract. To evaluate the prevalence and risk factors of Clonorchis sinensis infection, an epidemiologic survey was performed (3,169 residents; age range: 30-87 years; mean age ‫ס‬ 59; 1,973 women) in three areas with different mortality rates of cholangiocarcinoma. C. sinensis prevalence was 2.1% in Chuncheon, 7.8% in Chungju, and 31.3% in Haman, where cholangiocarcinoma incidence rate was 0.3, 1.8, and 5.5 per 100,000 persons, respectively. Of the four major risk factors for C. sinensis (male sex, alcohol consumption, raw freshwater fish intake, and area of residence), area was the strongest. Efforts to discourage raw freshwater fish intake, treat egg carriers, and protect water sources from C. sinensis contamination should be strengthened in the Republic of Korea.

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Pulsed-field gel electrophoresis techniques were used to examine the chromosomes of Pneumocystis carinii isolated from laboratory rats and two human subjects. P. carinii organisms isolated from each of four rat colonies and from two patients each produced a distinct band pattern, but in all cases the bands ranged in size from 300 to 700 kilobase pairs. P. carinùi from three rat colonies produced patterns containing 15 prominent bands. Of these 15 bands, 2 stained more intensely than would be expected of bands of their size, suggesting that the P. carinii haploid genome contains 17 to 19 chromosomes. Summing the molecular sizes of the bands and accounting for staining intensities suggested that the haploid genome of rat-derived P. carinii contains on the order of 107 base pairs. Human-derived P. carinii produced patterns containing 10 to 12 bands which appeared to be similar to the 15-band patterns seen in rat-derived P. caring with respect to the size range of the bands. P. carinii from the fourth rat colony produced a more complex band pattern containing approximately 22 bands, most of which appeared to comigrate with the bands present in one of the 15-band P. carinii patterns, suggesting that these animals were simultaneously infected by two different varieties of P. carinii. Hybridization experiments using oligonucleotide probes specific for the P. carinu 18S rRNA gene supported this possibility. The band pattern of P. carinii derived from a given rat colony was generally stable over time. P. carinii band patterns were not strictly rat strain specific and appeared to be transferable between animals housed in the same room.

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