Comparison of the effects of infection with Trichostrongylus colubriformis, T. vitrinus and T. rugatus in merino lambs

Groups of six worm-free merino lambs were infected with 100,000 larvae of T. colubriformis, T. vitrinus, T. rugatus or a mixture of the three species and were slaughtered 21 days later. Nematodes were distributed predominantly in the first 3 m of the small intestine where they caused subtotal villus atrophy. T. vitrinus caused severe erosion of the epithelium; erosion was less severe with T. colubriformis infections and mild with T. rugatus infections. Plasma concentrations of albumin declined during the experiment and were most marked in sheep infected with T. vitrinus. Plasma phosphate concentrations declined during infection with all three species, while plasma concentrations of globulin and calcium declined only in sheep infected with T. vitrinus. Food intake was reduced in all groups, but was most marked with sheep infected with T. vitrinus. T. vitrinus appeared to be more pathogenic than the other species.     

Distribution and pathogenicity during development of Camelostrongylus mentulatus in the abomasum of sheep

Fifteen lambs were each inoculated orally with 150 000 infective Camelostrongylus mentalutus larvae. Lambs were killed 3, 4, 8, 12, 16, 21 and 28 days after infection (DAI). Feed consumption and plasma total protein levels of the lambs killed 21 and 28 DAI did not differ significantly from those of uninfected controls. Three and 8 DAI most larvae were recovered from the fundic mocusa, but the intensity of establishment of larvae per gram of tissue was greatest at the cardia and diminished gradually toward the pylorus. Emergence of worms from the cardia and fundus occurred between 8 and 12 DAI, and a proportion of the lume-dwelling population shifted into the antral area, while the number of worms in the antral mucosa remained stable. Nodularity of the mucosa, mucous metaplasia of fundic epithelium, and vascular permeability as indicated by colloidal carbon label, were evident 3–4 DAI, and were most severe 8–12 DAI, when erosion of and inflammatory cell effusion from heavily infected mucosa was marked. pH and Na⁺ concentration in abomasal content were elevated at all times after infection, with peak values 12 DAI. Plasma pepsinogen levels in infected lambs were elevated beginning 3–12 DAI.     

The use of detector dogs in the diagnosis of nematode infections in sheep feces

This study was conducted to assess a dog's ability to differentiate between nematode-infected and uninfected sheep feces. Two German shepherd bitches were trained for scent detection over a 6-month period using operant/clicker conditioning. On completion of the training, testing was undertaken with 9 paper bags containing uninfected and 1 with infected feces, placed randomly around a circle. The dog and handler were not able to observe the placement of the bags. The 10th bag contained feces from sheep infected with either Teladorsagia circumcincta, Trichostrongylus vitrinus, Haemonchus contortus, or a mixed infection of all 3 species. Over 80 trials the dog had a mean success rate of greater than 80% in the detection of T. circumcincta- or T. vitrinus-infected feces and H. contortus-infected feces was detected with a slightly lower reliability of 76%, but mixed infections were detected at 92% reliability (one-proportion binomial analysis, P < 0.05). Trials were then undertaken to determine the time after administration of infective larvae that the dog was first able to differentiate T. circumcincta infection in sheep feces. At 7 days postinfection (dpi), the dog was capable of identifying T. circumcincta at least 85% of the time. These trials demonstrate that dogs are able to detect the common parasite infections in sheep with reliability equal to immunological assays. The results suggest that diagnostics based on odor detection using dogs to identify signature odors which could then be used to create sensitive detection devices might allow parasite detection on-farm and on all sheep in a flock.     

Expansion of intracellular IFN-γ positive lymphocytes during Mycoplasma agalactiae infection in sheep

A method to assess the expansion of antigen-specific intracellular IFN-γ positive T cell subsets during the infection will be helpful for a better understanding of mycoplasmal infections physiopathology in the sheep. We analysed the percentage of antigen-specific lymphocytes positive for intracellular IFN-γ during the infection of sheep with Mycoplasma agalactiae by culturing peripheral blood mononuclear cells of infected or uninfected animals with irradiated M. agalactiae. The expansion of antigen-specific IFN-γ positive lymphocytes in infected sheep was initially sustained by CD4⁺ T cells at day 15 after infection, when antigen specific IgG start to be detectable, followed by CD8/IFN-γ double positive cells. γδ T-cells were not expanded at any time point analysed. IFNγ⁺ T cells disappear 60 days after infection, suggesting that antigen specific IFNγ⁺ T cells, mainly detected in the early phase of the disease, could be useful to understand the role of cell-mediated immunity during M. agalactiae infection.     

Effect of isometamidium on infections by Trypanosoma vivax and T. Evansi in experimentally-infected animals

Assays dealing with the therapeutic and prophylactic activity of isometamidium on experimental infections by Trypanosoma vivax and T. evansi were carried out. The drug was found to be highly effective against T. vivax infection in sheep and cattle in which periods of protection ranging from 118 to 195 days were achieved. No complete effects against infection by T. evansi were observed. The drug was well tolerated in sheep and cattle while side-effects were noted in treated mares. It was concluded that isometamidium could be used to prevent damage and economical losses caused by T. vivax in Venezuela.     

Synthesis of glucose-6-phosphatase in small intestine mucosa during experimental coccidiosis in suckling piglets]

Glucoso-6-phosphatase activity (EC. 3.1.3.9.) was evaluated microdensitometrically in the small intestine mucosa of 19 conventional piglets infected with Eimeria debliecki coccidium oocysts (infection dose of 200,000 oocysts) on day 1 after delivery (DAD). The synthesis of the observed hydrolase was followed within days 1 to 10 after infection (DAI). The activity of the same enzyme was also determined in four control conventional piglets at the age of two to five days. The small intestine mucosa of healthy piglets was found to have relatively balanced glucoso-6-phosphatase concentrations in all observed sections (duodenum, middle and posterior jejunum and ileum). The topographic gradient failed to be demonstrated in control piglets. In piglets experimentally infected with E. debliecki coccidium the glucoso-6-phosphatase activity was decreasing during infection already since DAI 1. The enzyme hypoactivity was still lower in the following days and reached the minimum value at the end of the target period (DAI 10), when its value made only 33% of the concentration recorded in the intestine mucosa of control piglets. The topographic predisposition to the lower activity of glucoso-6-phosphatase was not found to be high. The only exception are DAI 6 and 7, when the lowest enzyme concentration was observed in the duodenum mucosa (52% on DAI 6; 54% on DAI 7). The activity of the observed enzyme was higher in the other sections of small intestine (57% on DAI 6; 62% on DAI 7).     

Morphogenesis of Trichostrongylus rugatus and distribution during development in sheep

Morphogenesis of Trichostrongylus rugatus was examined in 16 sheep experimentally-infected with 120 000 third-stage larvae and killed 2, 4, 6, 8, 10, 12, 16 and 20 days later (DAI). Third stage larvae moulted between Days 4 and 6, and fourth stage larvae moulted on Day 10 after infection. Four sheep first passed eggs in the faeces between Days 16 and 18 after infection. Rate of growth of larvae was constant between 2 and 10 DAI followed by a period of rapid growth from 10 to 16 DAI. Major features of larval development are described. Nematodes were largely restricted to the first 6 m of gut with 71% of worms occurring in the first 3 m.     

Dehydrogenase activity in small intestine mucosa in experimental coccidiosis in suckling pigs]

The activities of 3-beta-hydroxybutyrate dehydrogenase (EC. 1.1.1.30.; HBD) and isocitrate dehydrogenase (EC. 1.1.1.41; ICD) were evaluated microdensitometrically in the mucosa of duodenum, jejunum and ileum of 19 conventional piglets infected on the first day after parturition (DAP) with oocysts of Eimeria debliecki coccidium (infection dose of 200,000 oocysts). The two investigated enzymes are deposited in mitochondria which are dispersed in the supra-, para- and infranuclear region of absorption cells (Fig. 1). The synthesis of the two dehydrogenases was investigated in the small intestine mucosa in the period of 1st to 10th day after infection (DAI). The HBD and ICD activities were also followed in the small intestine of four control conventional piglets at the age of 2-5 days (Tab. I). The two dehydrogenases could be characterized by a topographic gradient; it means that their activity was increasing in the small intestine mucosa through duodenum in an aboral direction. The ICD activity is higher in the intestinal mucosa of healthy piglets (Figs. 2 and 3), where its topic concentration was more marked while the HBD activity is dispersed in enterocytes (Fig. 4). In infected piglets the density of the two enzymes was demonstrated to decrease already in the starting period of experimental infection, and it reaches the lowest values for the first time on DAI 5-6 (Fig. 5, Tab. II), then on DAIs 9 (HBD; Fig. 6, graph 11)) or 8 (ICD, Fig. 7 and 10). In the period of experimental infection no statistically significant predisposition to the hypoactivity of target dehydrogenases nor its marked shift were observed. Somewhat rapid resumption of synthesis was demonstrated as soon as on DAI 8 in ICD (Fig. 8); its activity on DAI 10 in the intestinal mucosa corresponded to the 93% activity of this dehydrogenase recorded in the small intestine of control piglets. The density of HBD to the same day (DAI 10) reached in the intestinal mucosa of infected piglets the values making only 44.7% of those demonstrated in the intestinal mucosa of the control group of animals.     

Experimental toxoplasmosis in buffalo calves

Eight buffalo calves were inoculated with infectious oocysts of a virulent strain of Toxoplasma gondii, five with 1 × 10⁵, and the other three with 5 × 10⁵ oocysts each while two more were kept as non-inoculated controls. Infected animals developed pyrexia, anorexia, conjunctivitis and dyspnoea. The clinical symptoms, haematological changes and serological response were of a low order. The appearance of haemagglutinating antibodies at significant levels (? 1:64) was first observed at 21 days after inoculation (DAI), peaked at 42 DAI and rapidly declined after 63 DAI. The inoculated calves were killed (or died) at intervals from 11 DAI to 110 DAI. The organism could be recovered from several times of a calf that died 11 DAI, but was rapidly removed subsequently. Only the lymph nodes were infective till 32 DAI. Parasitism of the retina was demonstrated in one calf. The significance of these findings is discussed.     

The establishment and development of Trichostrongylus colubriformis in goats

Twelve goats were inoculated with 20,000 infective larvae of Trichostrongylus colubriformis and two were killed on each of Days 4, 7, 11, 14, 18 and 21 after inoculation (DAI). The number of worms that established, and the site of development were recorded. Most of the worms established within the first 3 m of the small intestine. There was little relocation or loss of nematodes after establishment. The worms started to migrate from the mucosa to the lumen 11 days after infection. At 4 DAI, 63% of the worms were still at the late L3 stage; the remainder of the worm population had completed the third moult to the L4 stage. The population at 11 DAI comprised largely young adults. When 21 DAI was reached, about 57% of the female worms had eggs in their uteri.     

Thymus atrophy during early pregnancy and its effect on a Trichinella spiralis infection in mice,including intestinal pathology and blood eosinophilia

The effects of pregnancy on the course of a $\text{Trichinella spiralis}$ infection and associated histopathological changes in thymus and small intestine were studied in outbred Swiss mice. For this purpose pregnant mice were orally infected with $\text{T. spiralis}$ on various days (1 to 8) $\text{post coitum}$. Virgin, age-matched infected and non-infected mice served as controls.Pregnancy induced a severe but reversible thymus atrophy, which was even more marked during a $\text{T. spiralis}$ infection. Thymus atrophy was most dramatic during mid and late pregnancy. During the involution phase a distinct increase in mast cells was observed.In animals infected during early pregnancy a not statistically significant inhibitory effect on worm expulsion was observed, whereas no effect was seen on the yield of muscle larvae, small intestine pathology (numbers of eosinophils, intestinal mast cells and globule leucocytes), blood eosinophilia and antibody production.Infection given during mid-pregnancy exerted an inhibitory effect on blood eosinophilia.On the basis of these results, it is concluded that although a severe atrophy of the thymus occurs during mid and late pregnancy, no effect on worm expulsion and intestinal pathology was observed when the infectious agent was given before thymus depletion started.     

Differential pulmonary immunopathology of domestic sheep (Ovis aries) and bighorn sheep (Ovis canadensis) with Mycoplasma ovipneumoniae infection: A retrospective study

Mycoplasma ovipneumoniae is a respiratory pathogen that impacts domestic sheep (Ovis aries; DS) and bighorn sheep (Ovis canadensis; BHS). BHS are reported to be more susceptible than DS to developing polymicrobial pneumonia associated with M. ovipneumoniae infection. Using formalin-fixed paraffin-embedded tissues, we performed a retrospective study investigating the pulmonary immune response of DS and BHS to M. ovipneumoniae infection. M. ovipneumoniae infected DS exhibited a more robust and well-organized BALT formation as compared to BHS. Digital analysis of immunohistochemical chromogen deposition in lung tissue was used to quantitate T cell marker CD3, B cell markers CD20 and CD79a, macrophage markers CD163 and Iba1, and cytokine IL-17. A significant interaction of species and infection status was identified for CD3, CD163, and IL-17. BHS had a greater increase in bronchiolar CD3 and bronchiolar and alveolar CD163 with infection, as compared to DS. BHS had an increase in bronchiolar associated lymph tissue (BALT) and alveolar IL-17 with infection, while these remained similar in DS regardless of infection status. IL-17 in respiratory epithelium of bronchi and bronchioles comparatively decreased in DS and increased in BHS with infection. These data begin to define the interspecies differential immune response to pulmonary M. ovipneumoniae infection in DS and BHS and provide the first investigations of respiratory epithelium-associated IL-17 in ovine.     

Densitometric analysis of aminopeptidase M activity in small intestine mucosa in piglets experimentally infected with Isospora suis

In gnotobiotical and conventional piglets infected a day post partum (DPP) with oocysts of the coccidium Isospora suis, densitometrical analysis of the activity of aminopeptidase M (EC.3.4.11.2; APM) was performed in the area of microvillous zone of the small intestine. Piglets were infected with different infection doses of oocysts (100,000 oocysts) in gnotobiotical piglets and 200,000 oocysts in conventional piglets). In infected gnotobiotical piglets, the APM activity was studied in the period from the 3rd to 11th day after infection (DAI) and in infected conventional piglets in the period of to the 2nd to 10th day after infection (DAI). Control piglets, in the group of the gnotobiotical animals at the age of 2 to 5 days in the group of the conventional animals at the age of 4 to 7 days, had different APM activity in the microvillous zone of the intestinal mucosa. It was stated that the microvillous zone of the intestinal mucosa gained higher values in control conventional piglets (+7.01 mean values of density). In infected gnotobiotical piglets the density fall of the reaction product of APM was demonstrated already on the third day with further marked reduction of APM density on the 4th day after infection in the whole small intestine with predominance of the persisting APM activity in ileum. Even despite the slight increase in the density of the reaction product of APM in the period from the 5th to 7th DAI (the highest increase in APM density on the 6th DAI), a further decrease of the activity was recorded again on the 8th and namely the 9th DAI in the whole small intestine (the lowest value of density was found in the rear jejunum), the ileum mucosa being affected, too. A slightly higher density of the reaction product of APM was found in the duodenum. On the 10th DAI the APM density started to change and on the 11th DAI in the duodenum and in the middle jejunum it even reached higher values in comparison with the control data. Some differences were proved in the infected conventional piglets in comparison with the development of the APM activity in the small intestine mucosa in the infected gnotobiotical piglets. On the 3rd and 4th DAI APM defect occurred in the whole small intestine, with APM density prevailing in the ileum mucosa (like in the group of infected gnotobiotical piglets). The second period of decrease in APM activity lasted for almost four days (6th to 9th DAI).(ABSTRACT TRUNCATED AT 400 WORDS)     

The therapeutic efficacy and prophylactic activity of doramectin against Dictyocaulus viviparus in cattle

SUMMARY Three groups of 8, 4-month-old male Jersey or Jersey-cross calves were infected with 2400 Dictyocaulus viviparus L₃ larvae and either left untreated or injected subcutaneously with 200 μg/kg doramectin 5 or 25 days after infection (DAI). Lungworms were found in all untreated cattle (geometric mean = 49) at necropsy 39 or 40 DAI. None was found in any of the treated cattle. In a second experiment, groups of 6, 8-month-old calves were untreated or injected with 200 μg/kg doramectin 28, 21 or 14 days before each calf was challenged with 2700 D viviparus larvae. Lungworms were recovered at necropsy 32 to 34 DAI. The geometric mean worm burden in the untreated cattle was 550. This was reduced by 100%, 99.5% and 94.1% in calves treated with doramectin 14, 21 or 28 days, respectively, before infection. It was concluded that doramectin is a highly effective anthelmintic against D viviparus adult or L₄ infections of cattle, and that reinfection of treated cattle will be significantly reduced for at least 28 days after treatment.     

Alkaline phosphatase activity in goblet cells in the small intestine of piglets experimentally infected with the coccidium Isospora suis

Alkaline phosphatase activity (EC. 3.1.3.1.) in goblet cells was investigated in the small intestine of 16 gnotobiotic piglets infected one day after delivery (DAD) by different rates of oocysts of Isospora suis coccidia. At a high infection rate of I. suis (750,000) the goblet cells were found to be highly positive to alkaline phosphatase on day 3 to day 4 after infection (DAI). In piglets infected by a low infection rate of I. suis oocysts (100,000) the activity of alkaline phosphatase activity in goblet cells was proved on days 4 to 10 after infection. In the first group of piglets, the positive goblet cells prevailed in the middle region of jejunum, with the peak on 4th DAI. It the second group of piglets a marked increase in the alkaline phosphatase activity was recorded in the goblet cells in the posterior part of jejunum on days 4 to 5 after infection and on 10th DAI. No alkaline phosphatase activity in the goblet cells was demonstrated in the control gnotobiotic piglets at the age of two to seven days.     

Chronic infection with Trichostrongylus vitrinus in sheep. Pathological changes in the small intestine

Eight four-month-old sheep were infected daily for 90 days with 2500 Trichostrongylus vitrinus larvae. Infections were patent by week 3; mean faecal egg counts reached a peak of 645 epg at week 5, then subsequently declined. Mean worm burden at slaughter was 6100 (range 60--25,080). Two sheep had visible lesions in the small intestine at slaughter. In both sheep, numerous shallow red depressed areas extended for 5 to 7 metres distal to the pylorus while, in one, more extensive irregular depressed areas occupied the first 1.5 metres. Microtopographical examination and scanning electron microscopy showed that these affected areas were devoid of villi and contained numerous worms embedded in the mucosa. Histological examination revealed many similarities with the lesions caused by T colubriformis. Subtotal villous atrophy and crypt elongation were present in the intestines from five of the remaining six sheep, and in these the mucosa contained numerous mononuclear cells and intraepithelial globule leucocytes.     

The establishment and development of Haemonchus contortus in goats

Twelve goats were inoculated with 40,000 third-stage Haemonchus contortus larvae and two were killed on each of Days 4, 7, 11, 14, 18 and 21 after inoculation (DAI). The number of worms that established, and the site of development were recorded. More worms established in the fundic, than in the middle or pyloric thirds of the abomasum. Early development occurred within the mucosa; emergence into the lumen started between 7 and 11 days after infection. By 4 DAI, all worms had completed the third moult to the L4 stage. At 11 DAI the majority of the worms were adults. A mean of 13.2% of the female worms had eggs in their uteri at 18 DAI; by 21 DAI more than half of the female worms had eggs in their uteri. The development of H. contortus was essentially similar to that described in sheep.     

The incidence of adult and larval stage Taenia hydatigena in Uttar Pradesh (India)

A total of 1023 dogs of different breeds from different parts of Uttar Pradesh State were examined for the presence of Taenia hydatigena, and 810 sheep, 1015 goats and 1040 pigs were examined for the presence of Cysticerus tenuicollis, to determine the incidence of these parasites. In dogs, the incidence of T. hydatigena was found to be 40.95%. The rate of infection was higher in street dogs than in dogs kept indoors.Cysticercus tenuicollis was found in 37.03% of sheep, 27.29% of goats and 8.30% of pigs. The rate of infection was higher in sheep than in goats or pigs. A high incidence of infection was found in the rainy season. The intensity of infection was higher in old than in young animals.     

Lysosomal activity in enterocytes in the small intestine in piglets experimentally infected with Isospora suis

The lysosomal activity of enterocytes of the small intestine mucosa was investigated in gnotobiotic and conventional piglets experimentally infected on the first day after birth (DAB) by the oocysts of the coccidia Isospora suis. A method of the proof of beta-D-glucuronidase (EC.3.2.1.31.) activity was used to demonstrate lysosomes. The piglets were infected by different infection doses of oocysts (100,000 oocysts in gnotobiotic piglets and 200,000 oocysts in conventional piglets). In the gnotobiotic infected piglets the activity of beta-D-glucuronidase in enterocyte lysosomes was investigated in the period from day 3 to day 11 after infection (DAI) and in the infected conventional piglets in the period from day 2 to day 10 after infection. Comparing the control piglets, the group of gnotobiotic piglets at the age of 2-5 days and the group of conventional piglets at the age of 4-7 days, the higher activity of beta-D-glucuronidase was demonstrated in the lysosomes of intestinal mucosa enterocytes in the gnotobiotic control piglets (+5.30 of the average density value, Dx). In the infected gnotobiotic and conventional piglets the pattern of beta-D-glucuronidase activity was found to have three stages in the course of this infection. Two stages can be characterized by a great increase in the enzyme activity (DAI 3-9 in gnotobiotic piglets, DAI 2-3 and 7-9 in conventional piglets. The third stage, which is manifest mainly in the conventional infected piglets, is characterized by a marked decrease in the activity of beta-D-glucuronidase, reaching the level of control findings (DAI 10 and mainly 11 in gnotobiotic piglets. DAI 4-6 and 10 in conventional piglets). A topographical picture shows that the two stages of increase and the stage of beta-D-glucuronidase activity decrease occur in the whole small intestine without any predisposition defect of the enzyme in the different sections of the small intestine.     

Concurrent parasitic infections of sheep: depression of Trichostrongylus colubriformis populations by a subsequent infection with Oestrus ovis

Concurrent infections of sheep with Oestrus ovis and trichostrongyles of the digestive tract are common in the field. Previous results have shown that a previous infection with O. ovis adversely affects worm populations of either Trichostrongylus colubriformis or Haemonchus contortus. However, no information was available to determine the influence of the succession of infections on the expression of interactions between these parasites located in remote anatomical sites. In order to investigate the role of these modulating factors, an experimental study was conducted on four groups of na?ve sheep, examining the consequences of a delayed infection with O. ovis on a pre-existing population of T. colubriformis. group T was infected four times with 4000 T. colubriformis larvae on days 0, 14, 28 and 42 of experiment; group O received multiple infections with O. ovis first instar larvae on days 42, 49, 56, 70 and 77; sheep from group TO received both infections and animals from group C remained as uninfected controls. Faecal egg counts and eosinophilia were measured weekly throughout the study. At necropsy (day 91), the mucosal cellular responses in the nasal cavities (septum, turbinates, ethmoid and sinus) and in the digestive tract (stomach and small intestine) from all animals were analysed from histological sections. Infection of the digestive tract with nematodes did not modify the biology of Oestrus populations, as measured by the number and weight of larvae. In contrast, infections with O. ovis after T. colubriformis infection was related to significant reductions (P < 0.01) in nematode egg excretion and worm burdens. These changes were associated with significant modifications in populations of mast cells, globule leucocytes and eosinophils in the respiratory and digestive tracts. These results indicate that an antagonistic interaction exists between the populations of O. ovis in the nasal cavities and T. colubriformis in the small intestine but that the order of succession of infections with the two parasites is not a major modulating factor for expression of interactions. They also confirm that parasitic infection in one particular anatomical site induces "at distance" inflammatory reactions of the whole mucosal system.