Prepatent periods of different Oesophagostomum spp. isolates in experimentally infected pigs

To define prepatent periods of different Oesophagostomum spp. isolates we carried out two separate experiments, one using two monospecific laboratory isolates and another using laboratory isolates as well as isolates obtained from pig herds having different management systems and with different anthelmintic treatment histories. Pigs were inoculated with 1,000–2,000 infective larvae. Fecal samples were collected daily beginning on days 15 and 16 postinoculation (p.i.). Fecal cultures were set up at different times to yield larvae that could be identified by DNA analyses. All pigs started to excrete eggs on days 18–24 p.i. The mean prepatent period was 20.2 ± 1.4 days, with no significant difference being observed between species and isolates. Prepatent periods of 17–19 days were found for the monospecific laboratory isolates of O. dentatum and O. quadrispinulatum. These findings conflict with parasitology textbooks; therefore, suggestions as to the possible reasons for the observed short prepatent periods are given. Received: 13 November 1996 / Accepted: 15 January 1997     

Haematological changes in sheep experimentally infected with Trypanosoma evansi

 Sheep were infected with 2×10⁶ Trypanosoma evansi TREU 2143 through the external jugular vein. The parasite kinetics as well as the effects on body temperature, packed cell volume (PCV), erythrocyte counts and total and differential white blood cell counts were monitored twice weekly for 3 months. The results showed that T. evansi produced a chronic form of the disease in sheep characterised by low-level and often cryptic parasitaemia, with self-cure occurring in two cases; mild anaemia as evidenced by decreases in PCV and erythrocyte counts; and significant (P<0.02) leucocytosis by day 22 post infection (p.i.). The leucocytosis was a result of marked lymphocytosis whose significant rises (P<0.02) parallelled the rises in total white blood cell (TWBC) counts. These changes were less obvious in the animals that underwent self-cure. We conclude that T. evansi produces pathological changes in the peripheral blood of sheep similar to those produced by its tsetse-transmitted counterparts. It would thus appear that the sheep/T. evansi model is suitable for long-term study of the immunopathology of pathogenic trypanosomes since the sheep is easily available, easy to handle and a natural host to all pathogenic trypanosomes. Received: 17 July 1995 / Accepted: 11 January 1996     

Precipitating antibodies against maedi-visna virus in experimentally infected sheep

Summary Precipitating antibody was demonstrated by the Ouchterlony technique in sera of sheep, intrapulmonary or intracerebrally infected with maedi-visna virus. Debris from virus infected cultures of sheep choroid plexus cells served as an antigen. The precipitating activity of the serum was located in the IgG-fraction. The course of precipitating antibody was investigated in 16 experimentally infected animals and 11 controls divided over three experiments, which were terminated after 14 to 16 months, 4 years and 5 1/2 years, respectively. Precipitating activity could be detected within 2 to 8 weeks after exposure and persisted for the entire duration of the experiments. In the experiments lasting 4 and 5 1/2 years, four animals were encountered in which a positive precipitin test could not be confirmed by typical macroscopic or microscopic lesions at autopsy, despite the isolation of virus from the blood at irregular intervals during the experiment and the isolation of virus from the spleen of one of these sheep at the time of autopsy.     

Distribution of muscle larvae and antibody dynamics in goats experimentally infected with Trichinella spiralis

Herbivorous animals can play a very important role in spreading trichinellosis. In the study presented here, the susceptibility and distribution of Trichinella spiralis infection was examined in 16 goat kids. The goats were inoculated with 10,000 T. spiralis larvae isolated by artificial digestion methods. The animals were necropsied per two animals in weekly intervals, and the larval burdens in different muscle tissue and anti-Trichinella antibodies measured with the indirect enzyme-linked immunosorbent assay (ELISA) serological method using excretory–secretory (E/S) antigen for detecting anti-Trichinella antibodies were assessed during the experiment. T. spiralis larval burden was maximal at 6 weeks postinoculation (480–5,057 larvae/g according to locality), and the larvae were also found in the myocardium (0.77 larvae/g). In this paper, our next step was to compare the specificity and the time of seroconversion by means of ELISA based on E/S antigen prepared from T. spiralis. Antibody response was detected in all 16 goats. The ELISA test carried out showed the first increments in optical density 2 weeks postinfection (p.i.), reached their peak 4 weeks p.i., and remained elevated from that day until the end of the experiment (10 weeks p.i.). These results indicated that specific anti-Trichinella antibodies in goats persist for a relatively long time.     

Plasma ascorbic acid levels in sheep experimentally infected withFasciola hepatica

Three groups of sheep, one control (A) and two infected withFasciola hepatica metacercariae (B&C), were investigated. Each animal of group B was orally dosed with about 270 metacercariae and each sheep in group C received two such doses administered 14 days apart. In both infected groups, plasma ascorbic acid levels progressively decreased after exposure reaching a minimum by week 9, and then slightly increased during the subsequent five weeks. The decrease in ascorbic acid concentrations was mainly related to impaired synthesis as a result of the hepatic damage caused by the flukes.     

Haematological and plasma protein changes in sheep experimentally infected with Corynebacterium pseudotuberculosis

Two groups of sheep, experimentally infected with different doses of Corynebacterium pseudotuberculosis, were investigated; animals receiving high doses developed a septicaemia and died within 4 days of infection, while those inoculated with moderate doses survived, and were killed 4 weeks after infection with typical lesions of caseous lymphadenitis. A severe haemolytic anaemia, described as transitory macrocytic hypochromic, occurred in animals of the former group, while a less severe normocytic hypochromic anaemia was observed in the latter. Marked changes in plasma proteins and the haematological picture were found in animals of both groups, and these are discussed in relation to post mortem and histopathological findings.     

Observation on the schizont stage of an unidentified Theileria sp. in experimentally infected sheep

The schizont stage of an unidentified Theileria sp. infective for small ruminants was observed. Intact sheep were infected with adult Haemaphysalis qinghaiensis collected from fields where ovine theileriosis was prevalent. When the infested sheep developed theileriosis, tissue and organ smears were prepared. Theileria schizonts were demonstrated in liver, spleen, lung, kidney, lymph node and peripheral blood. Most of the schizonts were found outside the host cells, which was probably a smear artifact. This study adds our knowledge that lung and kidney can be parasitized by schizonts of Theileria sp.     

Actinobacillus spp. and related bacteria in infected wounds of humans bitten by horses and sheep.

We describe the isolation of Actinobacillus lignieresii and an A. equuli-like bacterium from an infected horse-bite wound in a 22-year-old stable foreman and A. suis from a bite injury in a 35-year-old man who had been attacked by a horse. A. lignieresii was also isolated in pure culture from an infected sheep-bite wound in a rural worker. These species of the genus Actinobacillus are primarily associated with animals and animal diseases and are rarely isolated from humans. The purpose of this report is to raise awareness of the possible occurrence of Actinobacillus spp. in bite wounds inflicted by farm animals and to discuss the difficulties encountered in the identification of species of Actinobacillus and related bacteria.     

Fasciola hepatica: Plasma ascorbic acid,plasma iron and iron-binding capacity in experimentally infected sheep

Six sheep were infected with about 520Fasciola hepatica metacercariae. Plasma ascorbic acid decreased after infection attaining minimum values by week 10 and subsequently increased. Plasma iron concentrations were elevated during the first 6 weeks of exposure and then decreased till week 10; the levels approached pre-infection values at weeks 11–13 and again dropped. The iron-binding capacity rose during infection especially between weeks 13 and 19.     

Studies on vertical transmission of Trichinella spiralis in experimentally infected guinea pigs (Cavia porcellus)

Parasitology Research - An experimental study to enhance knowledge on the capability of Trichenella spiralis to pass from guinea pigs to progeny at different periods of pregnancy or lactation was...     

Human antibody recognition of Anisakidae and Trichinella spp. in Greenland

High levels of total IgE are observed among children in Greenland. To evaluate the extent to which Anisakidae and Trichinella spp. contribute to the high total IgE level, an ELISA and a western blot were developed for the detection of IgG antibodies to Anisakidae, based on excretory/secretory antigens from Anisakidae larvae. Western blots with Anisakidae and Trichinella antigens discriminated between Anisakidae and Trichinella infections, enabling cross-reactivity between the two parasite infections to be eliminated. Serum samples from 1012 children in Greenland were analysed for specific antibodies to Anisakidae and Trichinella. Eleven children were IgG-positive for Trichinella and nine were IgG-positive for Anisakidae, indicating a relatively low prevalence of both infections among children in Greenland. Faecal samples from 320 children were also examined for other intestinal parasites. Enterobius vermicularis was found in one sample and Blastocystis hominis in 32 samples, but no other intestinal parasites were identified. In total, 304 children had elevated total IgE levels. There was a significant association between Trichinella seropositivity and high levels of total IgE, but not between Anisakidae seropositivity and total IgE. The data indicate that parasitic infections alone do not explain the high level of total IgE observed among children in Greenland.     

Capripoxvirus tissue tropism and shedding: A quantitative study in experimentally infected sheep and goats

Sheeppox virus and goatpox virus cause systemic disease in sheep and goats that is often associated with high morbidity and high mortality. To increase understanding of the pathogenesis of these diseases, we undertook quantitative time-course studies in sheep and goats following intradermal inoculation of Nigerian sheeppox virus or Indian goatpox virus in their respective homologous hosts. Viremia, determined by virus isolation and real-time PCR, cleared within 2 to 3 weeks post inoculation. Peak shedding of viral DNA and infectious virus in nasal, conjunctival and oral secretions occurred between 10 and 14 days post inoculation, and persisted at low levels for up to an additional 3 to 6 weeks. Although gross lesions developed in multiple organ systems, highest viral titers were detected in skin and in discrete sites within oronasal tissues and gastrointestinal tract. The temporal distribution of infectious virus and viral DNA in tissues suggests an underlying pathogenesis that is similar to smallpox and monkeypox where greatest viral replication occurs in the skin. Our data demonstrate that capripoxvirus infections in sheep and goats provide additional and convenient models which are suitable not only for evaluation of poxvirus-specific vaccine concepts and therapeutics, but also study of poxvirus-host interactions.     

Concentration of bluetongue virus in experimentally infected sheep and virus identification by immune fluorescence technique

Summary Most of the bluetongue virus in the blood of reacting sheep infected with unmodified virus is associated with the buffy coat. Although tissue cultures can be used for virus isolations, sheep proved the most sensitive of the systems tested. Spleen and mesenteric gland are the best organs for virus isolation from dead sheep. The reaction using the fluorescent antibody technique is group specific and can be used for rapid virus identification.     

Histopathology of the reproductive system of male sheep experimentally infected with Toxoplasma gondii

The aim of this study was to investigate the histopathological changes in reproductive system (testicles, epididymis, seminal vesicles, and prostate) of small male ruminants after Toxoplasma gondii infection. Eight sheep were inoculated with T. gondii: group I, four sheep (2.0 × 10⁵ P-strain oocysts); group II, four sheep (1.0 × 10⁶ RH-strain tachyzoites); and group III, two uninfected sheep maintained as control. Infection with T. gondii was confirmed by seroconversion (indirect fluorescent antibody test-IgG) in all the infected animals beginning on post-inoculation day (PID) 7. On PID 70, all the animals were euthanized and tissue samples (testicles, epididymis, seminal vesicles, and prostate) were collected and processed for histological analysis. The main changes detected were a focal mononuclear interstitial inflammatory infiltrate in the prostate and seminal vesicles; diffuse testicular degeneration associated with calcification foci and a multifocal mononuclear interstitial inflammatory infiltrate; and a mononuclear interstitial infiltrate and focal necrotic areas of the muscle fibers surrounding the seminal vesicles. The histopathological findings of this work, along with the detection of T. gondii in the examined parenchyma tissues (immunohistochemistry) and the results obtained by other authors examining different tissues, suggest that histological changes diagnosed in the reproductive system of rams infected with T. gondii are strongly suggestive of toxoplasmatic infection.     

Antibody and cytokine responses to hydatid in experimentally infected Kazakh sheep with hydatidosis resistance haplotype

Different MHC haplotype of Kazakh sheep has different resistance and susceptibility of hydatidosis. Notably, the MvaIbc-SacIIab-Hin1Iab haplotype of MHC-DRB1 exon two was associated with resistance hydatidosis. In order to analyze the antibody and cytokine responses to hydatidosis in Kazakh sheep with hydatidosis resistance haplotype, eight Kazakh sheep with the haplotype of MvaIbc-SacIIab-Hin1Iab were chosen as the test group, and other eight, which were not associated with hydatidosis resistance or susceptibility, were taken as control. After experimentally infected with hydatid orally, the blood was collected on 0, 7, 14, 30, 45, 60, 75, 90, 105, and 120 days. Serum and mRNA level of the cytokines IL-2, IFN-γ, TNF-α, IL-4, and IL-10 were evaluated by ELISA and fluorescence quantitative real-time polymerase chain reaction, respectively. The total white blood cells and leukomonocytes were determined by automation cytoanalyze. The level of IgE, IgG, and IgM were evaluated by ELISA. The results showed that the total white blood cells and leukomonocytes in test group were significantly higher than in control on 7, 45, 90, and 105 days post-infection (p.i.). The serum level of IL-2 in test group was significantly higher than in control on 45 days p.i., while the difference of IL-2 mRNA expression between test and control group was not significant. The serum level of TNF-α in test group was significantly higher than in control at 90 and 105 days p.i., and the TNF-α mRNA in test group was also significantly higher than in control on 90 days p.i. The level of IgE, IgG, and IgM in test group was higher than in control, but none was significant. The results suggested that the test group, which was predominant of Th1, could induce the protective immunity, while the control, which was predominant of Th2, could induce the susceptibility to infection of hydatidosis.     

Serum enzyme activity and bilirubin concentration in sheep experimentally infected with Fasciola gigantica

Fasciola gigantica infection in sheep produced liver and lung lesions characterized by damage to blood vessels and parenchymal necrosis. In the lungs, the lesions were those of parasitic bronchopneumonia. The damage to the liver and lung tissues was accompanied by increased activity in serum of AST after 2 weeks, GD and SD after 4 to 5 weeks and GGT and 5′-NT from 8 weeks onwards. Bilirubin concentration was not affected.