Development of Strongylus vulgaris-specific serum antibodies in naturally infected foals.

Strongylus vulgaris is regarded as the most pathogenic helminth parasite infecting horses. Migrating larvae cause pronounced endarteritis and thrombosis in the cranial mesenteric artery and adjacent branches, and thromboembolism can lead to ischemia and infarction of large intestinal segments. A recently developed serum ELISA allows detection of S. vulgaris-specific antibodies during the six-month-long prepatent period. A population of horses has been maintained at the University of Kentucky without anthelmintic intervention since 1979, and S. vulgaris has been documented to be highly prevalent. In 2012, 12 foals were born in this population, and were studied during a 12-month period (March-March). Weekly serum samples were collected to monitor S. vulgaris specific antibodies with the ELISA. Nine colts underwent necropsy at different time points between 90 and 300 days of age. At necropsy, Strongylus spp. and Parascaris equorum were identified to species and stage and enumerated. Initial statistical findings indicate a significant interaction between foal age and ELISA results (p<0.042). All foals had initial evidence of S. vulgaris-directed maternal antibodies transferred in the colostrum, but then remained ELISA negative during their first three months of life. Foals born in February and March became ELISA positive at about 12 weeks of age, while those born in April and May went positive at about 15 and 21 weeks, respectively. Foal date of birth was significantly associated with ELISA results (p<0.0001). This could be explained by birth date-dependent differences in parasite exposure. One foal remained ELISA-negative throughout the course of 30 weeks during the study. A significant association was found between ELISA values and larval S. vulgaris burdens (p<0.0001) as well as a three-way interaction between S. vulgaris, S. edentatus, and P. equorum burdens (p<0.001). A plateau with a subsequent decline in ELISA values corresponded with S. vulgaris larvae leaving the bloodstream and migrating back to the intestine.

Histopathology associated with angiostrongylosis in Akodon species (Rodentia: Sigmodontinae) from Sierra de la Ventana, Buenos Aires, Argentina.

Angiostrongylus is a metastrongylid nematode genus that includes species found in carnivores, rodents, and occasionally primates (including humans). About 100 species of wild sigmodontine rodents occur in Argentina, 16 of which are species of Akodon. The lungs of Akodon azarae and Akodon dolores from Sierra de la Ventana, Buenos Aires, Argentina, were examined, and 2 of 10 A. dolores specimens were positive for angiostrongylosis, showing macroscopic lesions of verminous pneumonia. Adults found were identified as Angiostrongylus morerai. Histopathology of the lungs revealed multiple nodules in the interstitium, alveoli, and vessels, resulting in interstitial fibrosis and the destruction of small capillaries and arterioles. Since extensive pathology in the lung was noted here from only 2 adults, it is probable that heavier infections may cause mortality in their hosts. This is the first record of this nematode species from A. dolores , expanding its geographic distribution to the southwest of Buenos Aires Province, and the first description of the histopathology of larval angiostrongylosis in a wild rodent from South America.

A new blood fluke of the genus Cardicola (Trematoda: Sanguinicolidae) from Pacific bluefin tuna Thunnus orientalis (Temminck & Schlegel, 1844) cultured in Japan.

A new sanguinicolid blood fluke, Cardicola orientalis n. sp., is described from the afferent branchial artery and heart of Pacific bluefin tuna Thunnus orientalis (Temminck & Schlegel) cultured in Mie and Nagasaki Prefectures, Japan. The new species is most similar to C. ambrosioi Braicovich, Etchegoin, Timi et Sardella, 2006 from the Brazilian flathead, Percophis brasiliensis Quoy & Gaimard, but can be differentiated by the position of the female genital pore (in midline or slightly sinistral in C. orientalis vs. sinistral in C. ambrosioi) and much longer distance between male and female genital pore (101microm vs. 27microm). In wet mount preparations of infected fish, eggs were accumulated in great numbers in the gill lamellae and afferent filament arteries. Importance of this blood fluke infection of cultured Pacific bluefin tuna in Japan is discussed.

Ultrastructure of the body wall of female Philometra obturans (Nematoda: Dracunculoidea).

The somatic cuticle of adult female Philometra obturans (Prenant, 1886) (Nematoda: Dracunculoidea) consists of five zones and an overlying prominent fuzzy epicuticle, closely adherent to the gill arterial wall of the host. The cuticle is fenestrated and infiltrated with electron-dense substances. It protrudes into the hypodermis in the form of numerous protuberances. The plasma membrane of the hypodermis forms prominent infoldings within the subcuticular region. Numerous endosomes bud off from the cuticle into the hypodermis. Glycogen deposits are present within the hypodermis and muscle cells. The muscle cells are well developed, polymyarian in number (up to 30 in each quadrant) and coelomyarian in shape. The body wall of adult female P. obturans reveals several ultrastructural features which are common to the members of Filarioidea.

Pathogenicity of the gill artery worm Philometra obturans (Nematoda) in northern pike (Esox lucius) in southwest Finland.

The pathogenicity of female Philometra obturans (Prenant, 1886) was investigated. Fish samples were taken in May and June 2001 from Lake Littoistenjärvi, in southwest Finland. The intensity of infection varied between 1 and 4 worms, these being found in the afferent artery of the 2 outermost gill arches. The prevalence was 33.9% (n = 59). Host condition and tissue reactions were investigated through dissection and analysis of histopathology. The parasites obstructed the gill arteries, and the arterial wall was stretched around intact worms. Hypertrophy of the arterial wall was observed, especially when only disintegrating remains of the parasites were present. Infected pike were in a poorer condition after catch, transportation, and holding in aquaria and thus less tolerant to stress than uninfected pike. This was correlated with the number of infected gill arteries (P < 0.05). The results show that infection with this nematode has a detrimental effect on the host when combined with environmental or physiological stress and may result in host mortality.

Lesions caused by cardiovascular flukes (Digenea: Spirorchidae) in stranded green turtles (Chelonia mydas).

Evidence of infection with spirorchid flukes (Digenea: Spirorchidae) was sought at necropsy of 96 stranded green turtles, Chelonia mydas, that were examined during the course of a survey of marine turtle mortality in southeastern Queensland, Australia. Three species of spirorchid (Hapalotrema mehrai, H. postorchis, and Neospirorchis schistosomatoides) were identified. Severe disease due to spirorchid fluke infection (spirorchidiasis) was implicated as the principal cause of mortality in 10 turtles (10%), and appeared to be one of multiple severe problems in an additional 29 turtles (30%). Although flukes were observed in only 45% of stranded C. mydas in this study, presumed spirorchid fluke infection was diagnosed in an additional 53% of turtles, based principally on characteristic necropsy lesions and to a lesser extent on the histopathological detection of spirorchid eggs. Characteristic necropsy lesions included miliary spirorchid egg granulomas, which were observed most readily on serosal surfaces, particularly of the small intestine. Cardiovascular lesions included mural endocarditis, arteritis, and thrombosis, frequently accompanied by aneurysm formation. Resolution of thrombi was observed to occur via a combination of granuloma formation about indigestible components (spirorchid fluke egg shells) and exteriorization through the vessel wall, which resulted in granulomatous nodules on the adventitial surface. Septic aortic thrombosis complicated by disseminated bacterial infection, observed in five turtles, was recorded for the first time. Egg granulomas were ubiquitous in turtle tissues throughout this study. Although they generally appeared to be mild or incidental lesions, they were occasionally associated with severe multifocal granulomatous pneumonia or meningitis.

Systemic arterial dirofilariasis in five dogs.

Systemic arterial dirofilariasis is an unusual manifestation of heartworm disease of dogs that results from aberrant migration of Dirofilaria immitis into the peripheral arterial circulation. To expand the clinical characterization of systemic arterial dirofilariasis, 5 dogs evaluated at the North Carolina State University's College of Veterinary Medicine were reviewed. Common clinical presentations included hindlimb lameness, paresthesia of hindlimbs, and interdigital ischemic necrosis resulting from thromboembolic disease. Visualization of heartworms with angiography or ultrasonography confirmed the diagnosis in all cases. All 5 dogs were treated with an adulticide; 3 dogs were treated with thiacetasamide sodium and 2 with melarsomine dihydrochloride. Four of the 5 dogs survived the initial treatment period; 1 dog died of severe thromboembolic complications after thiacatarsamide sodium therapy. The treatment of systemic arterial dirofilariasis creates a therapeutic challenge because of multiple potential complications resulting from thromboembolic disease.

Angiostrongyliasis in a European patient: a rare cause of gangrenous ischemic enterocolitis.

Angiostrongylus costaricensis causes a clinicopathologic disease first observed in Costa Rica, mainly in children characterized by highly symptomatic eosinophilic gastroenteritis involving the terminal ileum, cecum, appendix, and ascending colon. A case of angiostrongyliasis in an adult Spaniard infected during a brief stay in Nicaragua is reported. We examined the macro-microscopic features of a right ileocolic resection of a 52-year-old patient. In the surgical specimen, multiple confluent ulcers, some perforated, were observed particularly in the terminal ileum. The intestinal wall was thickened, and the arterial branches presented necrotizing arteritis with thrombosis and a heavy infiltrate of eosinophils around the vessels. In addition, some granulomas were observed. Adult male and female forms of A. costaricensis were found in the lumen of many arterial branches and in the tissue of the omentum, surrounded by dense eosinophilic infiltrate. A. costaricensis causes an intense eosinophilic, necrotizing arteritis associated with thrombosis leading to severe ischemic lesions. This is the first case to be diagnosed in Europe. Incubation time was able to be established within a period of at least 14 days.

Histopathological criteria for the diagnosis of abdominal angiostrongyliasis.

An increasing number of cases of abdominal angiostrongyliasis have recently been diagnosed in southern Brazil. A comparative study of 19 confirmed cases and 15 suspected cases was undertaken to review the anatomo-pathology of the disease and to establish histopathological criteria for its diagnosis. The results were similar in both groups, except for the identification of the worm in the confirmed cases. Macroscopic features comprised two types: a predominant thickening of the intestinal wall (pseudo-neoplastic pattern) and a congestive necrotic lesion (ischemic-congestive pattern). Microscopically, three fundamental histopathological findings were detected: (1) a massive infiltration of eosinophils in all layers of the intestinal wall, (2) a granulomatous reaction and (3) eosinophilic vasculitis affecting arteries, veins, lymphatics and capillaries. We conclude that observation of this histopathological triplet excludes other causes of "eosinophilic gastroenteritis" and establishes the diagnosis of probable abdominal angiostrongyliasis.

Protection of yearling ponies against Strongylus vulgaris by foalhood vaccination.

The long-term efficacy of an irradiation attenuated larval (L3) vaccine against Strongylus vulgaris was tested in ponies which were reared on pasture. Prior to foaling, mares were divided into two groups. One group of mares and foals received regular (eight weekly) treatment with ivermectin and the second group remained untreated. Half the foals in each pasture group were vaccinated at eight to ten weeks of age. Foals were weaned at three to four months of age and maintained on separate pastures. At eight to ten months of age, ponies were placed in box stalls and half of each treatment group were challenged with S. vulgaris (5 x 1000 L3). Clinical signs and lesions typical of acute verminous arteritis were found at necropsy in the ivermectin treated non-vaccinated challenged yearlings. Ivermectin treated vaccinated challenged yearlings did not show these clinical signs, had markedly reduced to absent arterial lesions and showed an 89 per cent reduction in arterial larval burdens post mortem. Significant differences in clinical signs, arterial lesions or arterial larval burdens were not seen between vaccinated and non-vaccinated foals reared without benefit of ivermectin treatment.

Strongylus vulgaris in the tunica media of arteries of ponies and treatment with ivermectin.

A preliminary investigation was made into the effect of fourth-stage Strongylus vulgaris larvae sequestered in the tunica media of ileocolic arteries of pony foals treated with ivermectin. The foals had been reared parasite-free, inoculated with infective larvae and given orally a placebo or ivermectin paste. Two foals received subsequently one or two further inoculations with larvae and treatment with ivermectin. Arteriography was used to identify the lesions in the ileocolic artery following inoculation and their regression following treatment. At necropsy, foals were examined for lesions and larvae grossly and histologically. Ivermectin was highly effective against fourth-stage larvae and those present in the media appeared not to unduly affect the integrity of the ileocolic artery. Increased numbers of larvae were not found in the media of foals receiving repeat inoculations and repeat treatments. Larvae were not found in the media of foals treated with a placebo. The major pathological changes in the arterial wall of all foals were attributed to infection with S. vulgaris and there was no strong tendency for the damaged arteries to return to normal after the S. vulgaris were removed.

Elaeophorosis in white-tailed deer: pathology of the natural disease and its relation to oral food impactions.

The lesions of naturally occurring elaeophorosis in white-tailed deer (Odocoileus virginianus) were studied. Arterial changes caused by adult Elaeophora schneideri occurred mainly in cephalic arteries and were characterized by circumferential intimal thickening, disruption of the internal elastic lamina, and verminous thrombosis. Microfilariae caused focal necrosis and fibrosis in the myocardium, but produced only minor changes in other tissues. Radiographic studies indicated that E. schneideri can cause impairment of the cephalic arterial circulation in white-tailed deer. Eleven of 14 (78%) infected deer had oral food impactions, with sublingual impactions being most common. Seven deer with impactions had other oral pathologic conditions, such as gingivitis, loose or absent premolar and/or molar teeth, and remodeling and/or lysis of mandibular bone. The evidence indicates a relation between food impactions and infection by E. schneideri in white-tailed deer, but no definitive connection was established.

Evaluation of ivermectin against later fourth-stage Strongylus vulgaris in ponies at two and five weeks after treatment.

The efficacy of ivermectin against later fourth-stage Strongylus vulgaris larvae was studied in pony foals at 14 and 35 days after treatment. These foals had been reared parasite-free, inoculated with 500 infective larvae and 56 days later given either ivermectin at 200 micrograms/kg or a placebo intramuscularly. At necropsy, foals were examined for lesions and larvae grossly and histologically. Ivermectin was found to be highly effective (98.6%) against later fourth-stage larvae in five foals which were examined at 35 days after treatment, but not in five others examined at 14 days (72.5%). In some foals larvae were found in the tunica media of the ileocolic arteries. The conformation of these larvae appeared normal, but there were degenerative changes which suggested that they were dying or dead. Questions as to how the larvae attained that site and the consequences of their presence there were raised.

Zoonotic filaria in a subcutaneous artery of a child in Costa Rica.

A 2-year-old boy from a rural community of Costa Rica was admitted to hospital with a rash of increasing severity over an area of the flank about 8 cm in diameter. Sections of a biopsy from the center of the affected area revealed a necrotic mature, infertile, female filaria about 120 microns in diameter in a subcutaneous artery, surrounded by a layer of dense eosinophilic granulomatous reaction which at one point, along with the worm, extended into the dermis. The worm, readily distinguished from Dirofilaria, Onchocerca, Wuchereria and Brugia, was unidentified.

Spermatic artery obstruction caused by Angiostrongylus costaricensis Morera and Céspedes, 1971.

An 8-year-old boy was admitted to hospital with acute testicular pain. A diagnosis of torsion of the testicle was made, and an orchidectomy was performed. Histopathological study showed necrosis of the testicular parenchyma caused by arterial obstruction, and adults of Angiostrongylus costaricensis were found within the spermatic arteries. In addition, heavy eosinophilic inflammatory reactions and unfertilized eggs were observed in the excised tissues.

Effectiveness of ivermectin against later 4th-stage Strongylus vulgaris in ponies.

Twelve pony foals were reared worm-free and inoculated with Strongylus vulgaris. Approximately 8 weeks after they were inoculated, 6 foals were given ivermectin IM at a dosage rate of 200 micrograms/kg of body weight and 6 were given a placebo. All foals were necropsied 35 days after treatment. Ivermectin was 98.9% effective in eliminating later 4th-stage S vulgaris larvae located near the origin of major intestinal arteries and in reducing clinical signs and permitting resolution of lesions associated with verminous arteritis. One pony foal reared on pasture and with evidence of arteritis of the cranial mesenteric and ileocolic arteries on arteriography was treated with ivermectin at a dosage rate of 200 micrograms/kg of body weight. On arteriographs taken subsequently, there was evidence of regression of the lesion, and at necropsy 9 weeks after treatment, there was no arteritis or larvae in those arteries.

A random walk model for the migration of Strongylus vulgaris in the intestinal arteries of the horse.

A study of the migration of fourth stage larvae of the parasite Strongylus vulgaris in the intestinal arteries of the horse is presented. It is established, that the larvae migrate along the arteries in almost straight lines. It is suggested that this is primarily due to their ability to sense the curvature of the vessel wall, and not, as might have been expected, because of an ability to sense the direction of blood flow. A larva will sometimes alter its direction of motion when encountering a small off-branching artery. This behaviour suggests, that the migration of S. vulgaris larvae can be modeled as a one-dimensional discrete random walk on a long time scale. This model is simpler than any deterministic model and, in particular, does not require the existence of a predilection site. The available data is not, however, sufficient for a convincing, quantitative test of the model. The proposed reluctance of the larvae to bend into off-branching arteries is used to explain the crowding of larvae in the cranial mesenteric artery.