Kenneth S. Todd

SOURCES AND RESERVOIRS OF TOXOPLASMA GONDII INFECTION ON 47 SWINE FARMS IN ILLINOIS

Field studies were conducted on 47 swine farms in Illinois during 1992 and 1993 to identify sources and reservoirs of Toxoplasma gondii infection. Blood samples were obtained from swine and from trapped wildlife. Serum antibodies to T. gondii were determined using the modified agglutination test, incorporating mercaptoethanol. Antibodies to T. gondii (titer > or = 25) were found in 97 of 4,252 (2.3%) finishing pigs, 395 of 2,617 (15.1%) sows, 267 of 391 (68.3%) cats, 126 of 188 (67.0%) raccoons, 7 of 18 (38.9%) skunks, 29 of 128 opossums (22.7%), 6 of 95 (6.3%) rats, 3 of 61 (4.9%) white-footed mice (Peromyscus sp.), and 26 of 1,243 (2.1%) house mice (Mus musculus). Brains and hearts of rodents trapped on the farm were bioassayed in mice for the presence of T. gondii. Toxoplasma gondii was recovered from tissues of 7 of 1,502 (0.5%) house mice, 2 of 67 (3.0%) white-footed mice, and 1 of 107 (0.9%) rats. Feces of 274 cats trapped on the farm and samples of feed, water, and soil were bioassayed in mice for the presence of T. gondii oocysts. Toxoplasma gondii was isolated from 2 of 491 (0.4%) feed samples, 1 of 79 (1.3%) soil samples, and 5 of 274 (1.8%) samples of cat feces. All mammalian species examined were reservoirs of T. gondii infection. All farms had evidence of T. gondii infection either by detection of antibodies in swine or other mammalian species, or by detection of oocysts, or by recovery from rodents by bioassay. The possibility of transmission of T. gondii to swine via consumption of rodents, feed, and soil was confirmed.

Risk factors for transmission of Toxoplasma gondii on swine farms in Illinois

Two epidemiologic studies of risk factors for transmission of Toxoplasma gondii to swine were conducted for farms in Illinois. The first study was a cross-sectional survey of swine farms from the state of Illinois pseudorabies testing program, in which farm owners or managers were interviewed by telephone regarding presence of risk factors for transmission of T. gondii on the farm. There were 123 farms surveyed that provided blood samples for at least 30 sows. The mean sow seroprevalence was 19.5% (median = 10.0%). Multiple regression analysis of the association of sow seroprevalence with outdoor housing of sows, cat access to sow areas, number of sows, open feed storage and water delivery, delayed removal of carcasses, and presence of rodents on the farm indicated that higher sow seroprevalence was associated with cat access to sows (P = 0.009) and fewer sows in the herd (P = 0.05). The second study was a field investigation of 47 swine farms (37 from the cross-sectional study). Data collection included obtaining blood samples from swine, cats, and rodents, and fecal samples from cats, heart and brain tissue from rodents, and feed, water, and soil samples for T. gondii examination. The risk of T. gondii transmission from cats and rodents to sows and finishing pigs was evaluated, taking into account housing conditions and herd size. Multiple regression analysis indicated that T. gondii seroprevalence in finishing pigs increased with more seropositive juvenile cats on the farm (P < 0.0001) and higher seroprevalence in house mice (P = 0.0023).(ABSTRACT TRUNCATED AT 250 WORDS)

First Asexual Generation of Eimeria vermiformis Ernst, Chobotar, and Hammond, 1971 in Mus musculus

medium; and (8) treatment with 0.015 M sodium dithionite for 7 min then the complete excystment medium. RE 1. Results of the various treatment groups the excystment of H. rhigedana. See t xt for details. Figure 1 summarizes the results and reveals that the highest percentage of excystment occurred with treatment groups two and eight. These treatments increased the rate as well as the percentage of excystment. Although high percentages of excystment were also obtained with groups three and six, acid pretreatment may not be necessary, because a higher percentage of excystment was obtained with group eight. Since no excystment occurred in medium in which either trypsin and sodium taurocholate was used alone, there seems to be a synergistic effect between these two substances. This observation is in accordance with those of Howell (1970, J. Helminthol. 44: 35-56) on Echinoparyphium serratum, Fried and Roth (1974, loc. cit.) for P. acanathus, Fried and Grigo (1975, Proc. Pa. Acad. Sci. 49: 79-81) for E. flexum, and Fried and Butler (1978, J. Parasitol. 64: 175-177) on Echinostoma revolutum, but differ from those of Kirschner and Bacha (1980, J. Parasitol. 66: 263267) for H. quissetensis. Himasthla rhigedana and H. quissetensis are related species, however, they show some variation in their in vitro excystment patterns. This is possible because the former encysts in the open and the latter in bivalve mollusks. In view of the above, H. rhigedana excysts in the small intestine of the avian host, apparently under the influence of reducing conditions, pH, temperature and the synergistic action of trypsin and bile salts. This study was supported by NIH Grant RR8006 and the Atlanta University Resource Center.

Pathological changes in mice infected with tetrathyridia of Mesocestoides corti

Long-term studies in mice experimentally infected with the tetrathyridia of Mesocestoides corti have revealed disseminated lesions in the liver, lung, kidney, epididymis, and testicle.

EFFECT OF DESICCATION ON THE SURVIVAL OF INFECTIVE HAEMONCHUS CONTORTUS LARVAE UNDER LABORATORY CONDITIONS

When stored in water at 4 and 20 C, respectively, 42 and 36% of free 3rd-stage, infective larvae of Haemonchus contortus were alive after 256 days. When stored at -95 C, 73% of the free, desiccated larvae died during the 1st half hour and 80% during the 1st half day; thereafter no more died for 255 days, the duration of the experiment. Desiccation protected the larvae against death on storage at temperature below freezing, but it was harmful at temperatures above freezing. H. contortus larvae do not withstand a single episode of desiccation as well as Trichostrongylus colubrformis larvae.

Transplacental transmission of Dirofilaria immitis microfilariae in the dog.

on the rate of development to the fourth-stage larva. Parasitology 59: 215-231. ROGERS, W. P., AND F. BROOKS. 1976. Zinc as a cofactor for an enzyme involved in exsheathment of Haemonchus contortus. Int. J. Parasitol. 6: 315319. , AND . 1978. Leucine aminopeptidase in exsheathing fluid of North American and Australian Haemonchus contortus. Int. J. Parasitol. 8: 55-58. , AND R. I. SOMMERVILLE. 1957. Physiology of exsheathment in nematodes and its relation to parasitism. Nature 179: 619-621. , AND . 1960. The physiology of the second ecdysis of parasitic nematodes. Parasitology 50: 329-348. , AND . 1968. The infectious process, the rate of d velopment to the fourth-stage and its relation to the development of early parasitic stages of nematodes. Adv. Parasitol. 6: 327348. SILVERMAN, P. H., N. E. ALGER, AND E. L. HANSEN. 1966. Axenic helminth cultures and their use for the production of antiparasitic vaccines. Ann. N.Y. Acad. Sci. 139: 124-142. SOMMERVILLE, R. I. 1957. The exsheathing mechanism of nematode infective larvae. Exp. Parasitol. 6: 18-30. 1964. Effect of carbon dioxide on the development of third-stage larvae of Haemonchus contortus in vitro. Nature 202: 316-317. . 1966. The development of Haemonchus contortus to the fourth stage in vitro. J. Parasitol. 52: 127-136. e e elop ent of early para-

Spiroxys utahensis sp. n. (Nematoda: Spiruridae) from the Tiger Salamander, Ambystoma tigrinum nebulosum

Spiroxys utahensis sp. n. is described from the tiger salamander, Ambystoma tigrinum nebulosum, from Dry Lake, Cache County, Utah. The body length is 11.09 to 19.76 mm (avg 16.75) for males and 20.00 to 35.67 mm (avg 27.88) for females. Spicule length is 0.99 to 1.30 mm (avg 1.12). Spiroxys utahensis differs from all other Spiroxys species by having shorter spicules. On 30 May 1965, 20 adult tiger salamanders, Ambystoma tigrinum nebulosum, were collected from Dry Lake, near Wellsville, Cache County, Utah, to examine for intestinal helminths. Of these, two of three females and all of 17 males were found to be infected with an undescribed species of Spiroxys. The number of these nematodes varied from two to 78 (avg 21) per infected animal. A description of the study area was reported by Stanford (1965). After collection, the animals were placed in an aquarium and examined within 4 days. Nematodes were fixed in 70% alcohol + 5% glycerol at 60 C and cleared in glycerol. Permanent slides were made by mounting specimens in glycerol jelly. Some males were mounted in Hoyers solution (Benbrook and Sloss, 1961, p. 161) to allow more detailed study of the spicules. The following description is based on a detailed study of 20 specimens of each sex. Drawings were made with the aid of a camera lucida. All measurements are in microns unless otherwise stated; the mean is in parentheses following the range. Spiroxys utahensis sp. n. (Figs. 1-5)

Effects of repeated desiccation on survival of infective Cooperia punctata laarvae.

observed difference in development to the adult stage was due to inability of some of the larvae to infect the sheep at all or to early destruction by the sheep (before the nematodes reached the age of 7 weeks, when the lambs were killed). We wish to acknowledge the technical assistance in this study of Paul A. Boatman, Walter M. Guterbock, Michael R. Harres, Timed difference in development o the stage was due to inabil ty of some of the to infect the she p at all or to early deion by the she p (before the nematodes e the age of 7 we ks, when the lambs othy P. Howland, Michael W. Lemelin, Allen J. Paul, Robert M. Smith, and James R. Speiser.

Oocysts of Isospora ernsti n. sp. and Isospora blagburni n. sp. (Apicomplexa: Eimeriidae) from the black-capped bulbul, Pycnonotus xanthopygos

Oocysts of Isospora ernsti n. sp. and Isospora blagburni n. sp. are described from the black-capped bulbul Pycnonotus xanthopygos from Lincoln Park Zoo, Chicago, Illinois. The bird came from southwestern Africa seven years earlier. I. ernsti oocysts are ellipsoidal to bluntly ovoid, 28−38 × 23−31μm (mean 34 × 28 μm) and have a single-layered oocyst wall. Micropyle, oocyst residuum and polar granules are absent. Sporocysts are elongate ovoid, 24−30 × 11−16 μm (mean 27×13 μm). Stieda and substiedal bodies and sporocyst residuum are present. I. blagburni oocysts are spherical to subspherical. 21−28 × 19−26 μm (mean 25 × 23 μm) and have a single oocyst wall. Sporocysts are ovoid and 17−23 × 10−13 μm (mean 20 × 12 μm). Stieda and substiedal bodies and sporocyst residuum are present.

APLOPARAKSIS PICAE SP. N. (CESTODA, HYMENOLEPIDIDAE) FROM THE BLACK-BILLED MAGPIE, PICA PICA HUDSONIA (SABINE, 1823)*

Aploparaksis picae, a new hymenolepidid tapeworm from the black-billed magpie (Pica pica hudsonia) from Montana, is described and compared with the species of Aploparaksis from pas- seriform birds. The new species is distinguished by the size, shape, and number of rostellar hooks as well as the size and shape of the scolex and the arrangement and size of other organs. The incidence and intensity of infection in three age groups of magpies is presented.