Morphologic and clinicopathologic changes following Strongylus vulgaris infections of immune and nonimmune ponies.
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Biomedical subjects
Publications and source records attributed to T R Klei.
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A controlled test was used in ponies to compare the antiparasitic efficacy of ivermectin (22,23-dihydro-avermectin B1) in an injectable micelle solution administered IM with the efficacy of the same drug in an oral paste formulation. Parasite infections were naturally acquired in southern Louisiana. The drug was tested in both formulations at a dosage level of 0.2 mg/kg of body weight. Ivermectin in both formulations tested had an efficacy greater than 98% against Gasterophilus intestinalis and G nasalis larvae. Trichostrongylus axei, Habronema spp, Strongylus vulgaris, S. edentatus, and species of small strongyles present. Efficacy of ivermectin against Oxyuris equi larvae was 100% in the paste formulation and 93% in the injectable formulation. The ponies were less uniformly infected with S equinus, Draschia megastoma, Parascaris equorum, O equi adults, Anoplocephala perfoliata, and A magna. However, observations indicated that the drug in either formulation was also effective against these parasites, except Anoplocephala spp.
Nonimmune pony foals 9 to 12 mo of age were vaccinated with third-stage Strongylus vulgaris larvae (L3) irradiated with 70, 100, or 130 Kr of gamma radiation. Ponies receiving per os inoculations of L3 irradiated with 70 or 100 Kr were protected from the clinical disease and lesions associated with challenge infections of 4,300 L3, when compared to nonvaccinated controls. Similarly, the numbers of worms from the challenging population recovered from successfully vaccinated animals were significantly lower than from nonvaccinated controls. The degree of resistance that develops in individuals can be semiquantitated based on clinical and pathological responses.
Complement profiles were tested in outbred (LVG) Syrian hamsters (Mesocricetus auratus) and compared to the MHA, LHC, PD4, and CB inbred strains. The total C and C component concentrations in the sera varied among the strains and were in the following ranges in untreated animals (in CH50 units per ml): total C, 140-260 (undetectable in PD4 and CB); Cl, 14,000-25,000; C2, 200-800 (except PD 4 and CB); C3, 40,000 and 80,000; C4, 2,000-2,800 (except PD4 and CB); C4, 40,000-80,000; C6, 3,600-6,000 (undetectable in PD4 and CB); C7, 50,000-350,000; C8, 10,000-30,000; C9, 30,000-60,000. The PD4 and CB strains had undetectable total C and C6, and their exact C2 and C4 levels could not be determined, but were lower than in the other strains. The MHA strain had the highest total C levels, but had significantly lower (1/3 or less) C7 levels than the other strains of hamsters. Infection of hamsters with the filarid nematode Brugia pahangi for four to five months produced moderate decreases in the total C and C3 levels, but varied changes in other C components. Six infected and three uninfected animals died during the experiment from spontaneous enteritis and weight loss.
Two types of experiments were used to study the degree of tissue responsiveness which occurred in Brugia pahangi-infected jirds. In experiment 1, the severity of lymphatic lesions which developed following subcutaneous infection of jirds which has existing intraperitoneal infections was compared to the severity of lymphatic lesions that developed following subcutaneous infection of jirds without previous infections. In experiment 2, comparisons were made of the sizes of granulomas which formed in the lungs around cyanogen bromide-activated Sepharose 4B beads coupled with B. pahangi antigen, which were inoculated intravenously into jirds which: 1. had existing lymphatic infections; 2. were uninfected. Results of both experiments indicated that jirds with intraperitoneal or lymphatic infections of B. pahangi of 120 to 160 days duration were significantly less responsive to B. pahangi or B. pahangi antigens as measured by pathologic tissue reactions than were uninfected jirds. The sizes of granulomas which formed around beads coupled to B. pahangi antigen in noninfected and nonsensitized jirds suggest that this worm material may contain factors which nonspecifically enhance the granulomatous inflammatory reaction.
The major organs, other than lymphatics, of jirds (Meriones unguiculatus) with prepatent and chronic patent infections of Brugia pahangi were studied by standard histological, electron microscopical and fluorescent antibody techniques. Changes observed and not previously described in detail or in large numbers of animals are reported. Multifocal non-suppurative interstitial nephritis was observed in 4% on animals with patent infections of 163 days duration and in 69% of animals with patent infections of 274 days duration. Glomerular changes were not observed in kidneys of any animals infected with B. pahangi. The occurrence of large granulomata composed of lymphocytes, macrophages, eosinophils and giant cells in the liver and smaller granulomata in the spleen correlated with patency of infections but microfilariae or worm antigens were not observed in these areas. Amyloid deposits were demonstrated in the spleen of 4% of animals with patent infections of 163 days duration and in 38% of animals with patent infections of 274 days duration but were not seen in uninfected animals of the same age or animals receiving only challenge inoculations of 28 days duration.
The effect of existing Brugia pahangi infections on the establishment of a subsequent population was studied using jirds which had pre-challenge infections of 4 and 8 months duration. Necropsies were performed 28 days post-challenge inoculation in order to separate challenge and initial worm populations. The results indicate that existing infections of 4 or 8 months duration increase the susceptibility to subsequent homologous infections. The location of challenge population worms in tissue sites examined did not differ significantly between previously infected and uninfected groups. Previous infections did not affect the early growth of challenge population worms as indicated by their length.
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The controlled test method was used to evaluate the antiparasitic efficacy of IM inoculated 22,23-dihydroavermectin B1 (ivermectin) against gastrointestinal parasites of horses (ponies). Parasite infections were naturally acquired in southern Louisiana. Dose levels of the drug tested were 0.2 mg/kg, 0.3 mg/kg, and 0.5 mg/kg. Ivermectin at all dose levels tested had an efficacy greater than 97% (P less than 0.05) against Gasterophilus intestinalis larvae, Trichostrongylus axei, Oxyuris equi larvae, Strongylus vulgaris, S edentatus, 15 species of small strongyles, and small strongyle larvae. Ponies were less uniformly infected with Habronema sp larvae, G nasalis larvae, Parascaris equorum, O equi adults, Anoplocephala perfoliata, S equinus, and 11 small strongyle species, and statistical analysis was not possible to do. However, observations indicate that the drug was also highly effective against these species. There were no gross or clinical reactions observed in treated animals. Dissections of the injection sites revealed spindle-shaped lesions, 3 to 5 cm long, in a few ponies in all treatment groups, including those given the placebo injection.
Capillaria hepatica infection was diagnosed by histologic examination in 21 of 71 (30%) coyotes in Louisiana. All infected coyotes were at least 1 year old, and most (19 of 21) were more than 2 year years old. Capillaria hepatica was not found in any livers from 31 red foxes and 20 gray foxes examined.
Syrian hamster sera may be assayed for hemolytic complement (C) activity by standard procedures with sensitized sheep erythrocytes as used for human sera, but mongolian gerbil sera had higher complement titers when tested with sensitized guinea pig erythrocytes as target cells. The optimal conditions for in vitro testing of hamster C were pH 7.3, ionic strength 0.15, and presence of 1 micrometer of Mg2+ and 0.3 micrometer Ca2+. For gerbil C the optimum pH was 8, ionic strength 0.074, and the same concentration of Mg2+ and Ca2+ as for hamster. Incubation at 37 degrees C for 60 minutes yielded optimal results. Complement components in the serum of both species could be tested with commercially prepared intermediates of sheep erythrocytes pretreated with guinea pig C1 and human C4 respectively, using purified human C2 through 9 and standard methods applied for testing human C components. Both species have all nine components of the complement system.
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Host suitability, reproduction, effects of temperature on reproduction and pupal development, effects of humidity on pupal development and the effects of photoperoid on puparial deposition, pupal development and adult emergence were studied in a laboratory colony of Pseudolynchia canariensis. Flies were observed to lack strong host specificity. Puparia were produced at regular 24 h intervals by flies maintained at 30 degrees C, averaging 8-8 puparia per female. Optimum temperature for colony maintenance was observed to range between 26-6 and 30-0 degrees C. Temperatures of 13 and 37 degrees C were lethal to pupae. Humidity and photoperiod did not markedly affect pupal development. Puparial deposition and adult emergence occurred only during the photoperiod.
Seasonal prevalence of Haemoproteus columbae and its vector Pseudolynchia canariensis in the feral pigeon (Columba livia) population of Detroit, Michigan has been studied for 5 years. The greated prevalence of H. columbae infection occurs during fall and winter and is lowest during the spring, correlating with changes in the vector population.
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