Early Development of and Pathology Associated with Strongylus edentatus

Pony foals inoculated with infective Strongylus edentatus larvae were monitored for clinical signs and selected blood changes and were examined at necropsy from two to 56 days postinfection. Larvae penetrated the intestine and reached the liver intravenously before 40 hours postinfection. Occasional thrombi and larval tracks associated with the intima of cecal and colic veins suggested aberrant paths. Larvae in the liver doubled in width between seven and 15 days postinfection and a sudden increment in circulating eosinophils occurred between 11 and 15 days. These changes were probably associated with the third molt. At 30 days fourth stage larvae were migrating in the liver; at 42 days they were present in the hepatorenal ligament.

White foci were observed in the liver from two to 56 days. They contained mononuclear cells and eosinophils and later necrotic cores of eosinophils. By one month foci were overshadowed by tortuous tracks of migrating larvae. Aberrant larvae in the lungs were confined in granulomas. Massive granulomas in the wall of the cecum and colon contained small larvae which were probably inhibited by antibody associated with the third molt. Severe disruption of omental architecture and adhesions involving the intestine occurred several weeks after infection.

     

The effect of radiation on the viability and migratory ability of second-stage larvae of Toxocara canis in mice

Larval counts were made on mice 2 days after oral inoculation with X-ray (0-320 Krad) or of gamma ray (0-6 Mrad) irradiated eggs containing second-stage Toxocara canis larvae. The majority of the larvae irradiated with 0-40 Krad were recovered from the liver and lungs, while most of the larvae irradiated with 80 or 160 Krad remained in the digestive tract, mainly in the stomach and the proximal half of the small intestine. Only a small number of the 320 Krad irradiated larvae was recovered from the mice. No significant difference was observed in the viability of irradiated larvae incubated in vitro up to 13 days after irradiation. However, a substantial percentage of the 160 and 320 Krad-irradiated larvae hatched during that period. Very few larvae were recovered from the digestive tract of mice inoculated with eggs irradiated with 0.5 Mrad, and only one and four larvae were recovered from the liver and lungs of a mouse. No visceral larval migration was observed in mice inoculated with 1 Mrad-irradiated eggs. The minimum lethal radiation dose for second-stage T. canis larvae in eggs is proposed to be 1 Mrad.     

Experimental infection of pups with Ancylostoma caninum-infected mouse tissues

Migration and distribution of Ancylostoma caninum larvae in the tissues of mice orally infected with 1000 larvae, and establishment of patent infection from the mice to the definitive host, were studied. Larval yield from different organs of mice, after digestion with artificial gastric juice, indicated that the highest recovery was at 4 h post-infection (62.8%), and thereafter a slight decline occurred up until 30 days post-infection (51.5%). Migration of larvae to the lungs occurred within 4 h, to the liver within 12 h and into the heart within 24 h. No larvae were recovered from spleen and kidney tissues. From the 9th day onwards larvae were also recovered from the brain. Migration in the muscles of head and neck occurred within 4 h, in the thoracic and abdominal muscles at 24 h and in lumbosacral and leg muscles at 48 h. The establishment of patent infections in the definitive host was studied by feeding the orally- and percutaneously-infected mice to hookworm-free pups at 10 and 30 days post-infection. The mean necropsy worm burden in the pups fed with the orally-infected mice was comparatively higher than in the pups fed cutaneously-infected mice.     

Canine mammary cancer

Microscopic examination showed that mammary cancer in the dog, especially the more infiltrating types, had often been removed (±50%) in an incomplete way. Local recurrence, detected clinically or at post mortem examination, is frequent.
Metastasis is the most frequent cause of death. Dyspnoea is often, but not always, associated with pulmonary metastasis. Lymphogenous and haematogenous metastasis are common.
By-passing of regional lymph nodes and lungs is extremely uncommon. Pleural metastasis was only found in combination with pulmonary metastasis.
Tumours in the posterior glands had more frequently spread to the lungs and liver than those in the anterior glands. Haematogenous spread to other mammary glands was not detected. Multiple malignant mammary tumours were found to be rare (4%).
Mammary cancer should be treated both surgically and systemically.     

Toxocara cati larvae persist and retain high infectivity in muscles of experimentally infected chickens

The distribution of Toxocara cati larvae in the organs of chickens (n=31), experimentally inoculated with 3000 embryonated eggs, was examined 1, 2, 3, 7, 29, 86 and 175-176 days post-infection (dpi), and the infectivity of recovered larvae was evaluated by bioassay in mice. The duodenum, liver, lungs, heart, brain, pectoral muscles (white meat), and hindlimb muscles (red meat) of the chickens were HCl-pepsin digested for larval recovery. Larvae were recovered from all chickens [mean=220.4 ± 114.9 (SD)], and although no decrease of total larval recovery was observed over time, predilection sites changed: liver (92.6% of larval recovery) at 1 dpi; lungs (77.3%) and liver (20.9%) at 2 dpi; lungs (80.8%), muscles (9.4%), and liver (8.5%) at 3 dpi; muscles (52.0%) and lungs (45.6%) at 7 dpi, whereafter most larvae were recovered from muscles: 29 dpi (99.5%), 86 dpi (99.3%) and 175-176 dpi (99.6%). In the bioassay, 52.9% of larvae from 175 to 176 days old infections in chickens established in mice, which demonstrates that T. cati larvae retain infective in the muscles of chickens for half a year. These results highlight the zoonotic potential of poultry meat as a causative agent of human toxocarosis.     

The development of Ascaris suum in calves.

To determine the development of Ascaris suum after a primary and a secondary infection, 18 calves were inoculated with 2,000,000 infective eggs and examined from 18 hours to 13 days postinfection. At 18 hours larvae were recovered from the wall of the abomasum, duodenum and jejunum. They were found in small intestine lymph nodes on the third day, in the liver at five days and were most abundant in the lungs on days 7 and 9. The pattern of recovery of larvae from the lung between days 5 and 13 postinfection was similar after a primary or a secondary infection. Slower growth of larvae following a secondary infection was the only evidence of resistance to A. suum. There were no pathological changes observed in the alimentary canal. White foci were found on the surface of the liver as early as the third day. The rapid decline in the number of A. suum in the lungs after the ninth day was considered to be related to immobilization or death of larvae soon after the reaction to them commences.     

Strongylus edentatus: development and lesions from ten weeks postinfection to patency.

Pony foals inoculated with infective Strongylus edentatus larvae were examined at necropsy from ten to 72 weeks postinfection. At ten weeks postinfection larvae were visible retroperitoneally in the liver and flanks and were recovered from the ligaments of the liver. The fourth molt was detected at 16 weeks postinfection and larvae were also recovered from the wall of the cecum at this time. By 40 weeks adult S. edentatus containing eggs were found in the contents of the cecum and colon. While many larvae migrate to remote parts of the body, it is likely that only those that attain the base of the cecum are successful in establishing in the cecum and colon as adult forms. By 36 weeks postinfection no larvae were found in the liver and up to this time none were found in the peritoneal cavity. Larvae were not recovered from the parenchyma of the lungs. Adhesions and disruption of omental architecture were frequent changes observed throughout infection. Casts of necrotic eosinophils enclosing tracks and larvae were observed beneath the intima of major veins of the cecum and colon. The liver was rough and the capsule thickened at 16 and 20 weeks postinfection and the flanks remained edematous until 36 weeks postinfection.     

Bacterial pathogens associated with lung lesions in slaughter pigs from 125 herds

Relationships between macroscopic lesions and Polymerase Chain Reaction (PCR) detection of Mycoplasma hyopneumoniae (Mhp), Pasteurella multocida (Pm), Actinobacillus pleuropneumoniae (App), Haemophilus parasuis (Hps) and Streptococcus suis (Ssuis) of the lungs of 3731 slaughter pigs from 125 herds were assessed in France. Pneumonia and pleuritis were the most frequent lesions (69.3% and 15% of the lungs, respectively). Mhp, Pm, App, Ssuis and Hps were detected in 69.3%, 36.9%, 20.7%, 6.4% and 0.99% of the lungs, respectively. Mhp and Pm were associated with pneumonia at both the pig and herd levels. Pleuritis was not associated with any pathogen at the pig level, but was associated with a high percentage of pigs PCR-positive for App at the herd level. Measures focused on control of Mhp, Pm and App should significantly reduce the occurrence of both pneumonia and pleuritis.     

Efficacy of ivermectin in oral drench and paste formulation against migrating larvae of experimentally inoculated Parascaris equorum

Twenty-one mixed-breed pony foals, reared and maintained under parasite-free conditions, were used to test the efficacy of ivermectin in oral drench and paste formulations (200 micrograms/kg) against 11-day-old migrating larvae of Parascaris equorum. Three replicates of 4 foals and 3 replicates of 3 foals were formed on the basis of age. Foals in replicates of 4 were randomly allocated to be indicators, or to receive vehicle (control) or ivermectin paste or ivermectin liquid. Foals in replicates of 3 were randomly allocated to receive vehicle or ivermectin paste or ivermectin liquid. The recovery of larvae from the lungs, liver, and small intestines of the indicator foals showed that 99.9% of the larvae were in the lungs 11 days after inoculation (day 0 of treatment). The recoveries of larvae from lungs and small intestines of controls at 25 days after inoculation indicated that all larvae had migrated to the small intestine by this time. The mean length of larvae recovered from the lungs (11 days after inoculation) was 0.87 mm the mean length of those recovered from the small intestine (25 days after inoculation) was 3.65 mm. Using larvae recovered from small intestinal contents for calculations, ivermectin in both formulations was 100% effective against 11-day P equorum (P less than 0.01, compared with control group geometric mean of 1498.4).     

Strongylus equinus: development and pathological effects in the equine host.

The development and pathological effects of Strongylus equinus were studied in 17 pony foals and one horse foal raised in isolation and examined at necropsy from seven days to 40 wk postinfection (PI). Following inoculation of 15000 +/- 6% or 16000 +/- 6% infective larvae by stomach tube foals were monitored for clinical signs and selected blood changes. Larvae penetrated the wall of the ileum, cecum and colon. The molt to the fourth stage occurred mostly in the wall of the ventral colon before 2 wk PI and larvae attained the liver mainly via the peritoneal cavity as early as eight days PI and persisted in the liver until 17 wk PI. Following active migration within the liver, invasion of the pancreas was accomplished at least by 7 wk PI with maximum numbers at 17 wk. The fourth molt occurred about 15 wk PI and preadults were present in the wall of the ventral colon at 30 wk PI and in the lumen of the colon at 40 wk. Strongylus equinus tends to wander retroperitoneally to the flanks, perirenal fat, diaphragm, omentum and occasionally to the lungs. Between 1 and 4 wk PI small raised hemorrhagic areas were present on the serosa of the ileum and colon. Small white foci on the surface of the liver at 1 wk PI were followed by tortuous tracks 3 wk later. Pathological changes in the pancreas were evident at three months PI and more severe by four months. Granulomas containing larvae were common in the flanks, diaphragm, omentum and occasionally beneath the pleura of the lungs. Clinical signs were correlated with invasion of the pancreas, the fourth molt, maximum globulin values and high eosinophil counts.     

Examination of cattle with respiratory diseases for Mycoplasma and bacterial bronchopneumonia agents

A total of 247 mycoplasma strains was isolated from 435 lungs, tracheobronchial secretions and nasal swabs originating from cattle with symptoms of bronchopneumonia. Mycoplasma (M.) bovis was found 89 times (36%) and was the most common mycoplasma species in the lungs. M. bovirhinis, M. bovigenitalium, M. spec. and Acholeplasma (A.) laidlawii were isolated 158 times (64%). Among these mycoplasmas M. bovirhinis was the most widespread species (114 isolations). In 55 cases (62%) M. bovis was associated with Pasteurella or Actinomyces (A.) pyogenes. The other mycoplasma species were found in 67 cases (42%) together with these bacteria. Without mycoplasmas Pasteurella and A. pyogenes occurred in 33 of the probes investigated (21%). Beside mycoplasmas Haemophilus (H.) somnus was isolated from 16 of 162 tracheobronchial secretions investigated. The results confirm earlier suppositions that in most of the cases bronchopneumonia of cattle is a multifactorial event, frequently associated with mycoplasmas--especially M. bovis.     

Diversity of Ectoparasites in Sheep Flocks in Sa~o Paulo,Brazil

The occurrence of ectoparasites in sheep flocks is frequently reported but seldom quantified. Sheep production used to be a predominantly family activity in the state of Sa~o Paulo (Brazil), but it began to become a commercial activity in the past decade. Thus, information about the ectoparasites existing in sheep flocks has become necessary. The present data were obtained by means of questionnaires sent to all sheep breeders belonging to the `Associaça~o Paulista de Criadores de Ovinos' (ASPACO; Sa~o Paulo State Association of Sheep Breeders). Response reliability was tested by means of random visits paid to 10.6% of the respondents. Most of the properties (89.5%) reported the presence of one or more ectoparasites. Screw-worm (Cochliomyia hominivorax) was the most frequent ectoparasite (72.5%), followed by bot fly larvae (Dermatobia hominis, 45.0%), ticks (Amblyomma cajennense) and Boophilus microplus, 31.3%) and finally lice (Damalinia ovis, 13.8%). Combined infestations also occurred, the most common one being screw-worm with bot fly larvae (36.0%) followed by bot fly larvae with ticks (13.9%), screw-worm with ticks (9.3%), bot fly larvae with lice (6.9%), and ticks with lice (5.0%). The most common triple combination was screw-worm, bot fly larvae and ticks (12.8%). Breeds raised for meat or wool were attacked by bot fly larvae and ticks more often than other breeds. Lice were only absent from animals of indigenous breeds. The relationships among these ectoparasites are discussed in terms of sheep breeds, flock size, seasonality and the ectoparasitic combinations on the host.     

The relationship of systemic phycomycosis and aspergillosis,in cattle showing clinical signs of disease,to the occurrence of lesions in different organs

Cases of systemic phycomycosis and aspergillosis in cattle with clinical signs of disease were recorded from the literature. The incidence of these conditions in animals of different ages was noted in conjunction with the organ in which the lesions were found. The forestomachs and abomasum were considered separately from other affected organs. Phycomycosis was most commonly associated with the lungs and the other organ most frequently affected was the liver. Aspergillosis was a comparatively, rare event but appeared to affect the same organs. Of the stomach compartments, lesions occurred most often in the abomasum and the age of the animals may be important. Lesions in the lymph nodes are generally associated with animals showing no clinical signs of disease.     

Bronchus associated lymphoid tissue in the lungs of cattle: relationship to age

The occurrence and morphological features of bronchus associated lymphoid tissue (BALT) were examined by light and electron microscopy in the non-pneumonic left lungs of five age groups of cattle from neonate to aged adult. The amount of BALT was correlated with age. It was absent in neonatal lungs and increased progressively with age until it declined in aged adult cattle. Within age groups the occurrence and morphology of BALT was variable. Widely scattered lymphoid aggregates were the predominant morphological type of BALT in the bovine lung. Follicular development in BALT foci was less frequent and quite variable within individual lungs. Morphologically distinct lymphoepithelium overlying BALT foci could not be demonstrated in non-pneumonic bovine lungs.     

Filaroides hirthi: hyperinfective lungworm infection in immunosuppressed dogs

Filaroides hirthi is a pulmonary parasite found primarily in beagle dogs. The modes of transmission and the life cycle of this parasite have been described recently, and the possibility of an autoinfectious cycle has been suggested. In this paper, we report two cases of experimentally immunosuppressed beagles (4 mg/day of prednisolone for over four months) in which massive disseminated F. hirthi infections developed. Large numbers of F. hirthi adults were present in the lungs, and larvae were found in lungs, mesenteric nodes, intestinal walls, and liver. While only minimal cellular responses were associated with the adult worms, a conspicuous mononuclear cell reaction was found around the larvae in the tissues. Since our dogs were caged to minimize contact with their own feces, we suggest that autoinfection took place in these dogs. Heavy worm burdens probably were reached because the reduced immune responses against the larva facilitated their successful penetration of the intestinal wall and their recirculation within the host.     

Dictyocaulus species: cross infection between cattle and red deer

Aim: To discover whether cross infection between red deer (Cervus elaphus) and cattle is possible with either a bovine isolate of the cattle lungworm, Dictyocaulus viviparus, or with a cervine isolate of the lungworm, Dictyocaulus eckerti which is thought to be maintained primarily in deer. Method: Twelve cattle and 12 red deer were reared parasite-free from birth. At 3-4 months of age, half of each species (n=6) were experimentally infected with D. viviparus and the other half with D. eckerti. The course of infection was monitored for 34 days, after which the animals were slaughtered and the lungs removed to assess levels of infection. Results: Faecal larval counts demonstrated that patent Dictyocaulus infections occurred in all groups. At necropsy, adult worms were found in the lungs in all groups except the cattle that were infected with D. eckerti. The largest numbers of adult worms were found in the red deer infected with D. eckerti. Conclusion: It was demonstrated that both cattle and red deer could be infected with either D. viviparus or D. eckerti. However, D. eckerti larvae that originated from deer established more successfully in deer and D. viviparus larvae that originated from cattle established more successfully in cattle.     

Migration and growth of Neostrongylus linearis (Marotel, 1913) Gebauer, 1932 in sheep

In order to establish the mammalian parasitic cycle of the nematode Neostrongylus linearis 18 lambs were infected with 5000 third-stage larvae obtained from the snail Cernuella (Xeromagna) cespitum arigonis. In the subsequent days, larvae were found in the walls of the caecum and colon, in the liver and the lungs, suggesting that the bloodstream is the main migratory route. The presence of low numbers of migrating larvae in the mesenteric lymph nodes indicates that this route is probably secondary. The first still sexually undifferentiated, fourth-stage larvae were found in the lungs on the 8th day post-infection (p.i.) and the first sexually differentiated fifth-stage larvae, on the 10th day. Also described are the macroscopic changes of the parasitized organs.     

Locomotion behavior of cao vit gibbon (Nomascus nasutus) living in karst forest in Bangliang Nature Reserve,Guangxi, China

The cao vit gibbon is a critically endangered species. Only approximately 110 individuals remain in degraded karst forest along the China‐Vietnam border. Karst forest is unusual gibbon habitat. Currently, the canopy height of cao vit gibbon habitat is approximately 10 m. Research on the locomotor behavior of gibbons living in this particular forest type might provide important insight into locomotor stability and variability of gibbons. We used 5 min scan samples to record the locomotion mode, support use and canopy strata of gibbons in 3 groups for 2096 h between January 2008 and December 2009. Although cao vit gibbon habitat has a lower canopy in comparison to that of other forests inhabited by gibbons, cao vit gibbons displayed a similar overall locomotor pattern to other gibbon species (Symphalangus syndactylus, Hylobates lar and Hylobates agilis) in which brachiation dominate their locomotor behavior. Cao vit gibbons spent most of their time travelling on inclined branches (2–10 cm) in the middle stratum through the forest canopy. Adult females appear to more often employ safer modes of locomotion (bridging more often and brachiation less), while adult males choose riskier modes (leaping more and climbing less). As gibbons increased in body weight, as they grew from infant to adult, they tended to use larger supports. This research documented that locomotor behavior in Hylobatidae is strongly determined by anatomical characters, but cao vit gibbons also show the ability to use various supports, enabling them to survive in karst forest.     

Pulmonary bacterial deposition and clearance during ascarid larval migration in weanling pigs.

Pulmonary deposition and clearance of bacteria were measured in weanling pigs, half of which had been inoculated at age 31 days with larvated Ascaris suum ova. Seven days later, when breathing signs of larval migration were pronounced, all pigs were exposed to aerosolized Escherichia coli (strain B). Then, either immediately after aerosol exposure (for deposition assessment) or immediately after a 120 minute period in filtered air (for clearance), bacteria in the pigs' lungs were counted. Ascarid ova-inoculated pigs did not differ significantly from control pigs for number of bacteria in the lungs after aerosol exposure, but after the 120 minute clearance period they had 7.2 times more than did the control pigs. Thus, in weanling pigs, the breathing-pattern changes that were evident during ascarid-larval migration did not affect pulmonary deposition of inhaled bacteria significantly, but the presence of ascarid larvae in the lungs was associated with impaired pulmonary bacterial clearance.     

Biology and pathophysiology of Toxocara vitulorum infections in a rabbit model

Ten female New Zealand rabbits were infected via stomach intubation with eggs of Toxocara vitulorum at a dosage of 10 embryonated eggs per gram of body weight on Days 0, 35 and 72. Ten or 4% of the administered parasites passed in the feces during the 3 days following the first or second infection, but 32% after the third infection. Many larvae were passed in the third infection, but not in the first or second. Tissue parasite yields were 4.1% on Day 5, 2% on Day 15, 0.8% on Day 30, 0.1% on Day 65 and 0.06% on Day 101. Five hundred and ninety-three larvae were recovered from liver, 243 from lungs and 0 from muscles on Day 5; 282 from liver, 138 from lungs and 21 from muscles on Day 15; 151 from liver, 21 from lungs and 50 from muscles on Day 30; 0 from liver, 26 from lungs and 15 from muscles on Day 65; 0 from liver, 0 from lungs and 9 from muscles on Day 101. No larvae were found in other tissues. The size of the muscle larvae at 30, 65 and 101 days indicated that the parasites did not develop beyond the infective stage and suggested that they were probably hypobiotic organisms. Erythrocytes, packed cell volume and monocytes decreased, but eosinophils and basophils increased, after each infection. Serum enzyme levels indicated that liver damage occured only after the first infection, but muscle injury occurred after each infection and was increasingly more precocious after each infection.