It is known that X-ray and gamma-ray irradiation damage the living organism.
Erickson(1965) reported that the cercaria of Schistosoma mansoni exposed to gamma-ray could not recovered from mice. Hsii et al.(1962) studied similar experiments using mice and monkeys which were exposed to Schistosoma japonicum.
Immunological studies by using irradiated larvae were also reported by Zaiman et al.(1955), Kim(1957), Larsh et al.(1959) and Erickson and Caldwell(1965).
The present was designed to study the influence of X-ray or gamma-ray irradiation upon the following subjects; hatching, infectivity, and maturity of hookworm egg and larvae.
Ⅰ. Egg hatching.
Dog feces containg hookworm eggs was divided evenly and kept in polyethylene envelops. The doses of irradiation were 1,000∼9,000R(roentgen) of X-ray and 1,000∼]00,000R of gamma-ray from Co**60
The irradiated eggs were cultured and the hatched larvae counted. In the X-ray group, 9,000R irradiated eggs could hatch but we destroyed before reaching the developed into the filariform stage. The control and the lesser-irradiated group filariform stage. In the gamma-ray group, the eggs irradiated above 40,000R showed incomplete hatching only 39% of them hatched.
Ⅱ. Viability of the irradiated larvae.
The rhabditoid and filariform larvae were irradiated with the dose as that above and kept at room temperature changing the media daily. Both the rhabditoid and filariform larvae were still intact in the case of irradiation of X_ray up to 5,000R or gamma-ray up to 100,000R.
108 mice were divided into 10 groups and infected with 500 irradiated filariform larvae of Ancylostoma caninum to each mouse. The doses of irradiation were 1,000R to 100,000R.
The mice were sacrificed three days after the infection and the migrating larvae were collected by Baermann's method from lung, liver and muscle. In the group of 50,000R irradiation, the larvae were recovered in 50%, and in 100,000R group in 26% compared with control.
Nine dogs were infected with 100, 250 and 500 irradiation filariform larvae of Ancylostoma caninum to each dog and sacrificed three months after the infection and adult worms were collected from small bowel. The adults were recovered 50% in the
dogs of 10,000R irradiated group. In the roups of 20,000 and 50,000R irradiation, the adult was not found at all from the small bowel of the host.
Ⅳ. Egg productivity.
The reduction rates of E.P.G.P.F. (Egg per gram per female) were measured by Stoll's egg counting method during 35 days observation fter infection of irradiated filariform larvae of Ancylostoma caninum. In the groups of 10,000R irradiation,
E.P.G.P.F. decreased to 53∼41% compared with the control group, and in 20,000R∼50,000R groups none was seen.
SUMMARY AND CONCLUSION
Eggs and larvae of canine hookworm(Ancylostoma caninum) were irradiated with X-ray and gamma-ray, and the viability, infectivity were examined 1. The eggs which were irradiated by X-ray with intensity of 5,000R hatched about 60% and developed to infective stage, but gradually disappeared. In gamma-ray irradiated group, the hatching of eggs was greatly inhibited at the intensity of over 50,000R.
2. The larvae which were irradiated with gamma-rays even at the intensity of 100,000R neither rhabditoid nor infective stage, survived more than one month.
3. The infectivity of the irradiated larvae was decreased at the intensities of 40,000R and over.
4. Larvae which were irradiated with X-ray and gamma -ray were given to the proper host, the dog. The recovery rates of the adult worm were very low in the group of 9,000R by X-ray and 10,000R by gamma-ray, and no worm was found in the groups of above 20,000R in gamma-ray. The damage was more pronounced in the group of irradiated eggs than in the irradiated larvae group.
5. The egg-productivity was decreased when the larvae were irradiated above 10,000R before infection.
The above findings show that damage by irradiation is more marked in the egg stage than in larval stage and the intensity of irradiation above 10,000R inhibits the infectivity and maturity of the larvae.