Glenn A. Noble

Stress and parasitism. III. Reduced night temperature and the effect on pinworms of ground squirrels

Abstract Groups of the ground squirrel, Citellus armatus , were subjected to the stress of reduced nighttime temperature to determine the effect on the numbers of the cecal pinworm, Syphacia citelli . Stressed and control groups were given an anthelmintic and each animal was fed 500 infective worm eggs. Bedding was removed from the stressed groups at night and blocks of ice were placed among them, whereas the control animals had bedding and their cages were warmed by electric heat. After 2 weeks all animals were killed, weighed, adrenal glands weighed, and a count taken of the pinworms. The average adrenal weight in the stressed animals was 110 mg per kilogram of body weight and in the control animals it was 81 mg. Twenty of the 47 stressed squirrels became infected with an average of 11.5 worms while 6 of the 30 control animals became infected with an average of 2.8 worms. Results indicated that there was a definite response to cold stress which resulted in an increase in numbers of pinworms.

Stress and parasitism II. Effect of crowding and fighting among ground squirrels on their coccidia and trichomonads

Abstract Forty-six ground squirrels were caged in pairs for 47 days. One marked member of each pair was placed in a box for 2 hours every other day, during which time they fought. The other member of each pair was kept as a control. Fecal pellets of all animals were periodically examined and a record kept of the numbers of coccidial oocysts and trichomonads. Records began in the field at the time of trapping (i.e., field count). During the last 11 days the stressed group was left alone while the original control group was stressed. In the caged control animals the coccidial count went considerably below counts made from field animals. Although there was an increase in numbers of coccidia in all other experimental groups, the increase was not significant. Trichomonads in the stressed group showed significant increases over the field animals. When this group was relieved from stress, the trichomonad count dropped to field count levels. Variations in trichomonad count in other groups were not significant.

Leishmania braziliensis: physical and chemical stress in hamsters.

Abstract Eighty hamsters were inoculated via the skin of the nose with promastigotes of Leishmania braziliensis. Sixty, in groups of 10, were subjected to crowding, swimming, restraint, and to injections of dexamethasone and of ethylene glycol. Twenty were kept as controls. Ninety-five per cent of the injected animals that had nose ulcerations also developed large skin lesions on their backs. No control animals had back sores. Cultivation of tissues showed dissemination of infection to viscera or skin in 13.3% of the stressed and injected hamsters. No dissemination occurred in control animal. Results showed that cortisone, ethylene glycol, and the stress of restraint significantly favored the development and spread of leishmanial infection.

Stress and parasitism. I. A preliminary investigation of the effects of stress on ground squirrels and their parasites

Abstract The Uinta Ground Squirrel, Citellus armatus, in Jackson Hole, Wyoming, was selected for a study of stress and parasitism during the summers of 1959 and 1960. Two hundred and twenty-six squirrels were live-trapped; 72 of the animals were used as controls and 155 were subjected to the stress of heat and light, noxious stimulants, noise, crowding, darkness, hunger, annoyance, extreme confinement or caging without added stimuli. A carefully controlled dilution technique was devised to give a representative count of the cecal protozoa, mostly Trichomonas. Over the period of two summers there was an average increase of 48% in numbers of protozoa in the stressed animals as compared to the controls. The white blood cell count decreased as the numbers of protozoa increased. The weights of the adrenal glands, however, also decreased in the stressed animals. A continuing study will be made of these and of related problems.

Stress and Parasitism

Publisher Summary This chapter presents a study analyzing relationship between stress and parasitism. Groups of the ground squirrel, Citellus armatus, were subjected to the stress of reduced night-time temperatures to determine the effect on the numbers of the cecal pin worm, Syphacia citelli. Stress and control groups were given an anthelmintic and then fed 500 infective worms eggs each. Bedding was removed from the stressed groups at night and blocks of ice were placed among them whereas the control animals had bedding and electric heat warmed their cages. After two weeks all animals were sacrificed, weighed, adrenal glands weighed, and a count was taken of the pinworms. The average adrenal weight in the stressed animals was 110 mg per kilogram of body weight and in the control animals it was 81 mg. Twenty of the 47 stressed squirrels became infected with an average of 11.5 worms while 6 of the 30 control animals became infected with an average of 2.83 worms. There was a definite response to cold stress that resulted in an increase in numbers of pinworms.

Description of Nematobibothrioides histoidii (Noble, 1974) (Trematoda: Didymozoidae) and comparison with other genera.

Nematobibothrioides histoidii, inhabiting the body wall tissues of the sunfish, Mola mola, is characterized by its great length, reaching over 12 m, diverticulated excretory horns, large excretory tube, presence of 2 suckers, rudimentary pharynx, absence of gland cells around pharynx and ceca, oblong vitelline reservoir, and oval eggs, 17 by 15 mu. A description is given of the single species. Of 19 genera in the subfamily Nematobothriinae, 6 that possess the greatest similarity with Nematobibothrioides are compared. A brief discussion of didymozoid affinities is given.

Stress and parasitism: IV. Cold stress and Entamoeba

Fifty ground squirrels were subjected to the stress of lowered night temperature for three consecutive nights. The average number of Entamoeba per milliliter of cecal fluid per 100 gm of squirrel body weight was 2162, whereas the number of amebas in 40 field control animals averaged 1133. The result proved highly significant when evaluated statistically. Amebas in control animals placed in a warm cage increased in number to 1728 per ml per 100 gm of body weight. This increase was not statistically significant. Changing the diet of stressed squirrels did not appreciably alter the results.