An epidemiological investigation of congenital Schistosoma japonicum transmission in Hubei Province, PR China.

A cohort study was conducted in Hubei Province, China, following serious flooding of the Yangtze River in the autumn of 1998 to investigate the possibility of congenital transmission of Schistosoma japonicum in humans. The cohort investigated was comprised of 205 women and their 208 infants born between 1 September and 30 December 1998. Blood and fecal samples from all the women and their infants were collected and examined for S. japonicum infection. Positive specific antibody titers were found in 14 (6.8%) of the mothers, but no fecal egg excretion was observed. All infants had negative specific antibody titers and no S. japonicum eggs were found in their feces. Hence, the present study coud not confirm congenital S. japonicum transmission in humans. Further studies are highly wanted to study the impact of prenatal exposure of S. japonicum on the offspring.

Schistosoma japonicum in the pig: the influence of age on the host/parasite relationship.

The current study sought to elucidate a possible association between age and susceptibility to a primary infection with Schistosoma japonicum in pigs. Sixteen Landrace/Yorkshire crossbred specific pathogen-free pigs in three different age groups (group A-C), aged approximately 7, 24 and 37 weeks at the beginning of the experiment, were infected by intramuscular injections of 1,000, 1,500 or 2,400 cercariae, respectively. Fecal egg counts were obtained twice weekly from six to eight weeks post infection (wpi), and the pigs were killed 11 wpi. The number of worms collected were counted and sexed subsequent to perfusion. Tissue egg counts were estimated on samples from the liver. The worm recoveries for group A, B and C were 3.2%, 8.1% and 3.8%, respectively. No differences were observed between the male/female ratios of the three groups. The fecundity parameters, ie, fecal egg counts per mature female and liver egg counts per mature female, showed no significant differences between the three age groups. The results did not indicate any difference in susceptibility between the different age-groups of pigs to a primary infection with S. japonicum.

Recovery and distribution of Ascaris suum superimposed on a Schistosoma japonicum infection in pigs.

The aim of this study was to examine the effect of a primary patent Schistosoma japonicum infection on the establishment and location of a superimposed Ascaris suum infection in pigs. The study comprised two experiments each containing two groups of pigs. In the first experiment, 7 pigs were injected intramuscular (i.m.) with 800 S. japonicum cercariae and inoculated with 1,000 A. suum eggs 11 weeks post primary infection (ppi) and 8 pigs were inoculated with 1,000 A. suum eggs at the time of challenge infection. In the second experiment, 7 pigs were injected i.m. with 1,100 S. japonicum cercariae and inoculated with 1,000 A. suum eggs 16 weeks ppi and 8 pigs were inoculated with 1,000 A. suum eggs at the time of challenge infection. All pigs were slaughtered 10 days after the A. suum challenge infection. The number of white spots caused by A. suum on the surface of the liver was significantly lower in the groups with primary infections of S. japonicum compared with the control groups. However, the present experiments did not demonstrate any effect of a primary S. japonicum infection on the total recovery and distribution of an A. suum challenge infection.

Allozyme variation among six populations of the freshwater-snail Oncomelania hupensis in Zhejiang, China.

Thirteen enzymes encoded by 16 loci of six population of Oncomelania hupensis in Zhejiang, China, were investigated by means of starch gel electrophoresis. Ten loci (AO, 6PGD, ME, AKP, OCT-1, HBDH-1, HBDH-2, XDH, MDH and MPI) were monomorphic and 6 loci (OCT-2, PGI, AAT, PGM-1, PGM-2 and ACP) were polymorphic. Three enzymes (OCT, HBDH and PGM) were encoded by 2 loci. The results indicated that there were allozyme variations in two subspecies, O.h. hupensis and O.h. fausti in Zhejiang, China. Nei's multilocus genetic distances (D) between subspecies ranged from 0.167 to 0.265. Minor genetic distances were detected between populations of the same subspecies. The results indicated that the enzyme acid phosphatase (ACP) is a possible marker to measure the degree of susceptibility of O. hupensis to S. Japonicum.