Toxoplasma gondii의 가토감염에 관한 실험적 연구

Abstract

[한글]

Experimental Study on Infection of Toxoplasma gondii to Rabbits

Chang-Eui Hong, M.D.

Department of Medical Science, The Graduate School, Yonsei University

(Director: Professor Chin-Thack Soh, M.D.)

Toxoptasma gondii was first described by Nicolle and Manceaux(1908) from an

African rodent (Ctenodactylus gundi). Since that time the protozoa was detected

from various avian animals and mammals including human being in a number of

reports(Jacobs,1967; Faust et al.: 1970).

The first human case of toxoplasmosis was reported by Janku (1973) in

Czechoslovakia, who died with hydrocephalus and microphthalmus, and it is now

recognized that one-half billion people are involved as asymptomatic and

symptomatic toxoplasmosis(Kean 1972).

In related to the life cycle, Hutchison(1965) first suggested the oocyst could be

infective to animal and man, and he also reported that the cat was infected with

T.gondii by feeding them the mouse brain containing Toxoplasma cysts.

Dubey et al. (1970**a) found the coccidian oocyst, which was similar to Isospora

bigemina from the cat feces after feeding Toxoplasma-infected mice. Three typos of

infective form of Toxoplasma gondii have been reported: trophozoite in the acute

stage, cyst imbedded in the tissues and oocyst. The gametogony was also established

in the intestinal epithelium of the feline order. However, no report was appeared

on possibility of the gametogony in herbivorous animals.

The present study was designed to study the infectivity of Toxoplasma gondii, to

rabbit, a herbivorous animal. The possibility of Toxocara cams eggs and Ancylostoma

caninum larvae to transmit the protozoa into tissues was also studied. The

experimental animals were cat, rabbit and mouse. They were the hybrids, and

confirmed parasitesfree in intestines before experiment. Dye test was also

performed to identify the previous infection of T. gondii. Beverly strain of T.

gondii was used for inoculation test to rabbit, and RH strain for the dye test.

Toxocara canis eggs and Ancytostoma caninum larvae were obtained from usual

parasitological means. Serologic determination was done with revised Sabin-Feldman

dye test using the citrated plasma.

Administration of T. gondii oocysts to rabbits was grouped according to the

purpose of experiment.

Group Ⅰ was subjected mainly for infectivity study:

ⅰ). Oocysts 370 + Toxocara cansis eggs 300

ⅱ). Oocyats 300+ Ancyfostoma caninum larvae 300

ⅲ). Oocysts 300 only

ⅳ). Toxocara canis eggs 300 only

ⅴ). Ancylostoma caninum larvae 300 only

ⅵ). Control

Group Ⅱ was subjected:

ⅰ). Oocysts 50,000 to detect the parasitemia

ⅱ). Oocysts 50,000 for histopathology

The inoculated rabbits were examined with the subjects: body temperature, stool

test to find oocysts and blood samplings for dye tests. In all the animals

associated with the oocysts T. gondii infection was established regardless the

means of administration.

The results obtained are summarized.

No difference was observed between the experimental groups: Toxoplasma infection

only and mixed infection groups with Toxocara canis or Ancylostoma caninum. Body

temperature of the rabbits increased to the clinical level one week after the

administration and the dye test titer increased to peak on the 24th day of

inoculation. Four out of 6 rabbits which fed T. gondii oocysts expired within the

25th day of inoculation. The cysts were found in the brain of rabbit on the 24th

day of inoculation. Although no cyst was found from the brains of other 3 expired

rabbits, Toxoplasma oocysts were detected from the cat feces by feeding them to the

animal.

To study the parasitemia, 50,000 oocysts were fed to rabbit, and the venous blood

was taken out daily for 10 days, then injected to mouse intraperitoneally. The

cysts were found in the mouse brains 30 days after inoculation and confirmed the

parasitemia was established.

All of the expired or sacrificed rabbits showed pathologic changes: multiple

local necrosis associated with granulomatous inflammation in the brain and liver,

superficial ulcer with acute non-specific inflammation in the intestine and passive

congestion in spleen and abdominal lymphnodes. No specific finding in others

organs; lung. heart, kidney and abdominal muscles was observed.

Gametocytes were detected from the intestinal epithelia of the cat which fed with

Toxoplasma gondii infected mouse. However, in no case, oocyst excretion was found

from the rabbit feces throughout the present study.

From the above results it is concluded that the rabbit can be infected only with

the oocyst stage but no gametocyte stage is established in the intestine of the

rabbit. The rabbit may serve as an intermediate to transmit the parasite when

victimized by the stronger animals.

[영문]

Toxoptasma gondii was first described by Nicolle and Manceaux(1908) from an African rodent (Ctenodactylus gundi). Since that time the protozoa was detected from various avian animals and mammals including human being in a number of

reports(Jacobs,1967; Faust et al.: 1970).

The first human case of toxoplasmosis was reported by Janku (1973) in Czechoslovakia, who died with hydrocephalus and microphthalmus, and it is now recognized that one-half billion people are involved as asymptomatic and symptomatic toxoplasmosis(Kean 1972).

In related to the life cycle, Hutchison(1965) first suggested the oocyst could be infective to animal and man, and he also reported that the cat was infected with T.gondii by feeding them the mouse brain containing Toxoplasma cysts.

Dubey et al. (1970**a) found the coccidian oocyst, which was similar to Isospora bigemina from the cat feces after feeding Toxoplasma-infected mice. Three typos of infective form of Toxoplasma gondii have been reported: trophozoite in the acute

stage, cyst imbedded in the tissues and oocyst. The gametogony was also established in the intestinal epithelium of the feline order. However, no report was appeared on possibility of the gametogony in herbivorous animals.

The present study was designed to study the infectivity of Toxoplasma gondii, to rabbit, a herbivorous animal. The possibility of Toxocara cams eggs and Ancylostoma caninum larvae to transmit the protozoa into tissues was also studied. The

experimental animals were cat, rabbit and mouse. They were the hybrids, and confirmed parasitesfree in intestines before experiment. Dye test was also performed to identify the previous infection of T. gondii. Beverly strain of T. gondii was used for inoculation test to rabbit, and RH strain for the dye test.

Toxocara canis eggs and Ancytostoma caninum larvae were obtained from usual parasitological means. Serologic determination was done with revised Sabin-Feldman dye test using the citrated plasma.

Administration of T. gondii oocysts to rabbits was grouped according to the purpose of experiment.

Group Ⅰ was subjected mainly for infectivity study:

ⅰ). Oocysts 370 + Toxocara cansis eggs 300

ⅱ). Oocyats 300+ Ancyfostoma caninum larvae 300

ⅲ). Oocysts 300 only

ⅳ). Toxocara canis eggs 300 only

ⅴ). Ancylostoma caninum larvae 300 only

ⅵ). Control

Group Ⅱ was subjected:

ⅰ). Oocysts 50,000 to detect the parasitemia

ⅱ). Oocysts 50,000 for histopathology

The inoculated rabbits were examined with the subjects: body temperature, stool test to find oocysts and blood samplings for dye tests. In all the animals associated with the oocysts T. gondii infection was established regardless the means of administration.

The results obtained are summarized.

No difference was observed between the experimental groups: Toxoplasma infection only and mixed infection groups with Toxocara canis or Ancylostoma caninum. Body temperature of the rabbits increased to the clinical level one week after the

administration and the dye test titer increased to peak on the 24th day of inoculation. Four out of 6 rabbits which fed T. gondii oocysts expired within the 25th day of inoculation. The cysts were found in the brain of rabbit on the 24th day of inoculation. Although no cyst was found from the brains of other 3 expired rabbits, Toxoplasma oocysts were detected from the cat feces by feeding them to the animal.

To study the parasitemia, 50,000 oocysts were fed to rabbit, and the venous blood was taken out daily for 10 days, then injected to mouse intraperitoneally. The cysts were found in the mouse brains 30 days after inoculation and confirmed the parasitemia was established.

All of the expired or sacrificed rabbits showed pathologic changes: multiple local necrosis associated with granulomatous inflammation in the brain and liver, superficial ulcer with acute non-specific inflammation in the intestine and passive congestion in spleen and abdominal lymphnodes. No specific finding in others

organs; lung. heart, kidney and abdominal muscles was observed.

Gametocytes were detected from the intestinal epithelia of the cat which fed with Toxoplasma gondii infected mouse. However, in no case, oocyst excretion was found from the rabbit feces throughout the present study.

From the above results it is concluded that the rabbit can be infected only with the oocyst stage but no gametocyte stage is established in the intestine of the rabbit. The rabbit may serve as an intermediate to transmit the parasite when victimized by the stronger animals.