Chai Jy

Genetic difference in susceptibility and fatality of three strains of mice experimentally infected with Neodiplostomum seoulense.

The genetic influence on host susceptibility to Neodiplostomum seoulense infection and fatality of the host was studied in 3 inbred strains of mice (BALB/c [H-2d], C3H/He [H-2k], and C57BL/6 [H-2b]). The survival of the mice, worm expulsion kinetics, worm size, number of eggs produced per day (EPD), and number of uterine eggs were observed from day 1 to day 40 postinfection (PI) with 100 or 200 metacercariae per mouse. Infection with N. seoulense was highly lethal to all 3 strains of mice, but the lethality was dose-dependent and varied according to the genetic backgrounds of the mice. The C3H/He mice exhibited the highest mortality, the lowest worm burdens and EPD, and the quickest expulsion of worms. It is suggested that different genetic backgrounds of mice appear to affect the hosts capacity to expel N. seoulense and the fatality of the hosts themselves.

Role of Intestinal Goblet Cells in the Expulsion of Gymnophalloides seoi From Mice

Role of intestinal goblet cells (GCs) in the expulsion of Gymnophalloides seoi was studied using 4 strains of mice, ICR, C3H/HeN, BALB/c, and C57BL/6, after infection with 200 metacercariae isolated from oysters. On day 7 postinfection (PI), significantly higher (P < 0.05) worm recovery rates (WRRs) were observed in ICR (29.5 ± 12.0%) and C3H/HeN (14.8 ± 8.2%) than in BALB/c (5.7 ± 5.3%) and C57BL/6 (0.8 ± 1.1%) mice. Alteration of the GC mucins was marked in C57BL/6 mice. On day 14 PI, 5.2 ± 5.2% and 0.6 ± 0.7% of worms were recovered only from ICR and C3H/HeN mice. When C57BL/6 mice were immunosuppressed with prednisolone, WRR on day 7 PI increased to 11.7 ± 13.9%, whereas the GC hyperplasia and mucin alteration diminished significantly. The results suggest that expulsion of G. seoi from the intestine is dependent on immune responses of the host, and GCs may be an important effector.

Suppressed Cytokine and Immunoglobulin Secretions by Murine Splenic Lymphocytes Infected In Vitro with Toxoplasma gondii Tachyzoites

Mechanisms of host immunosuppression after infection with Toxoplasma gondii are unclear. This study was performed to observe cytokine and immunoglobulin secretions by murine splenic lymphocytes infected in vitro with live, nonreplicating (irradiated) RH tachyzoites on stimulation with concanavalin A (Con A) or lipopolysaccharide (LPS). For lymphocyte cultivation, 3 groups were prepared: coculture with live nonirradiated tachyzoites separated by a transwell (group T), live irradiated tachyzoites without a transwell (group R), and no tachyzoites (group C). Compared with group T, groups R and C, on stimulation with Con A, revealed significantly (P < 0.05) lower levels of interleukin-2 (IL-2) and IFN-γ, but not IL-10. The levels of IgG1, IgG2a, IgG2b, IgG3, IgA, and IgM were also significantly (P < 0.05) lower in groups R and C than in group T after stimulation with LPS. The results suggest that intracellular infection of murine splenic lymphocytes with T. gondii tachyzoites could impair their capacity to produce cytokine and immunoglobulin secretions.

Stictodora lari (Digenea: Heterophyidae): The Discovery of the First Human Infections

Stictodora lari Yamaguti, 1939 (Digenea: Heterophyidae) was originally reported as an avian intestinal parasite and is here reported in humans. The patients were adults, aged 46–69 (2 men and 4 women), who resided in coastal villages in Sachon-gun, Kyongsangnam-do, or Shinan-gun, Chollanam-do, in the Republic of Korea. The worms were recovered after praziquantel treatment and purgation with magnesium salts. A total of 15 S. lari specimens (1–10 per individual) was collected, together with 5 other species of intestinal flukes. The flukes were morphologically characterized by a small body size (0.70–0.86 mm long and 0.27–0.36 mm wide), a ventrogenital sac, and a gonotyl armed with 70–80 spines in the form of a comma or reversed comma lying along their lateral margin. The patients had eaten the raw flesh of mullets and gobies that had been caught in an estuary near their villages. To the best of our knowledge, this is the first record of a human S. lari infection.

A Human Case of Plagiorchis vespertilionis (Digenea: Plagiorchiidae) Infection in the Republic of Korea

Plagiorchis vespertilionis (Digenea: Plagiorchiidae) is generally considered a bat parasite, but here it is reported for the first time in a human. The patient was a 34-yr-old male who lived in a coastal village of Haenam-gun (county), Jeollanam-do (province), Republic of Korea. Only 1 worm, 2.6 mm long and 0.7 mm wide, was recovered after praziquantel treatment and purging with magnesium salts. The fluke was characterized by a large body size, a sucker ratio of 1:1, a straight cirrus organ, a short distance between the ventral sucker and ovary, well-developed vitellaria, a uterus with descending and ascending loops, and fully developed eggs with an average size of 32.5 × 17.5 μm. The patient had habitually eaten the raw flesh of snakehead mullet and gobies that had been caught near his village. The present case represents the first record of a human P. vespertilionis infection.

Surface Ultrastructure of the Advanced Third-stage Larvae of Gnathostoma nipponicum

The surface ultrastructure of advanced third-stage larvae (AL3) of Gnathostoma nipponicum was studied using scanning electron microscopy. The larvae were recovered from the grass snake Rhabdophis tigrina in the Republic of Korea. Parasites had a globular head bulb with a pair of lips at the anterior end and 2 labial papillae and an amphid on each lip. The head bulb was characteristically armed with 3 transverse rows of hooklets, averaging 36, 38, and 43 in number, increasing posteriorly. A total of 213–232 minute unidentate cuticular spines were present along the entire length of the larvae, forming the transverse striations. Two pairs of cervical papillae were located between the 8th and 12th transverse striations, and a pair of body papillae was seen laterally on the posterior third of the body. A pair of caudal phasmids was recognized near the posterior extremity. The surface ultrastructure of AL3 of G. nipponicum is unique compared with that of other species.

Recovery, Growth, and Development of Acanthoparyphium tyosenense (Digenea: Echinostomatidae) in Experimental Chicks

Chicks were experimentally infected with Acanthoparyphium tyosenense (Digenea: Echinostomatidae) metacercariae per os, and the growth and development of worms in this host were observed from days 1 to 38 postinfection (PI). The worms grew rapidly and matured sexually in the small intestine (chiefly in the jejunum) of chicks by day 5 PI, and survived at least up to day 38 PI, although worm recovery decreased after day 5 PI. Both parenchymal and reproductive organs increased greatly in size from day 2 to day 10 PI and then continued to increase gradually in size up to day 38 PI. The number of uterine eggs reached a peak on days 10 and 15 PI and then decreased gradually. The results suggest that chicks are a fairly suitable definitive host for experimental infection with A. tyosenense.