Cerebral larva migrans in a raccoon (Procyon lotor)

During 1997, gross and histopathologic examinations were performed on an adult female raccoon (Procyon lotor) that was live-trapped in Corvallis, Oregon. Multifocal eosinophilic granulomas indicative of neural and visceral larva migrans were observed. However, within these granulomas, the presence of parasitic larva was seen only in the cerebrum. Morphologic characteristics indicated that the nematode was an ascarid larva. However, it was smaller than the larva of Baylisascaris sp. This appears to be the first documented case of cerebral larva migrans in a raccoon.     

Epidemiological aspects of the first outbreak of Baylisascaris procyonis larva migrans in rabbits in Japan

Larva migrans caused by the common raccoon ascarid, Baylisascaris procyonis, is a zoonotic disease of critical importance in North America. Recently we encountered the first proven outbreak of this disease in Japan in domestic rabbits (Oryctolagus cuniculus) in a small wildlife park. In this park, raccoons (Procyon lotor) had been kept for 9 years, and one raccoon was donated to the park by a pet owner 8 weeks prior to the occurrence of an outbreak in rabbits. Of 12 total raccoons, three raccoons including the donated one shed B. procyonis eggs in the feces, and two of these positive raccoons were kept in metal mesh cages on wooden pedestals, 2 m distant from the rabbit enclosure. Circumstantial evidence indicates that the donated raccoon is the likely source of this outbreak. Treatment of the raccoons with an ascaricide and decontamination by extensive flaming of the cages and the contaminated dirt floor of the park achieved a transient disappearance of ascarids from all 12 enclosed raccoons. Three months after the control measures began, recurrent ascarid infection was detected in three young raccoons of less than 1.5 years of age. The potential risk of serious zoonosis by B. procyonis as well as the difficulty in a clearance of contaminated areas should be considered by pet owners and public health workers in Japan.     

Baylisascariosis (Baylisascaris procyonis)--a rare parasitic zoonosis in Europe

Raccoons (Procyon lotor) were imported from North America into Germany many decades ago, and nowadays they are part of the home wildlife fauna. Unfortunately, the raccoon roundworm, Baylisascaris procyonis, was also imported. This nematode species is well known as an important agent of larva migrans in more than 100 animal species including man in North America, causing a fatal neurological or severe ocular disease. There are also several respective reports from Germany. A review about the biology of B. procyonis as well as the occurrence, epidemiology, pathology, clinical symptoms, zoonotic aspects of the baylisascariosis and possible preventive measurements is given.     

Baylisascaris procyonis in raccoons (Procyon lotor) from eastern Colorado, an area of undefined prevalence

Baylisascaris procyonis is a zoonotic parasite that has been documented in raccoons throughout much of the United States; however, no published information on its occurrence is available for the transition zone from the Great Plains to the Rocky Mountains. Because this parasite can cause neural larva migrans and diffuse unilateral subacute neuroretinitis in humans (as well as other hosts), a more complete understanding of the distribution of this parasite seems warranted for public health reasons. The purpose of this study was to begin to fill in the gaps in our knowledge of the distribution of B. procyonis in an area of the US where there is, currently, no published information available. Fifty-three raccoons were collected throughout eastern Colorado during 2007-2010. Forty-six were examined by necropsy and seven by fecal flotation. Age (11 juveniles, 25 adults) and sex (16 males, 19 females) of the raccoons were recorded when intact carcasses were available. When available, feces were further processed for the detection of Giardia and Cryptosporidium using a direct fluorescent antibody detection method. B. procyonis was found in 31 of 53 raccoons (58.5%, 95% CI=44.1%, 71.9%). Mean intensity was 11.7 with a range of 1-49 worms per infected individual. There was no significant difference between age or sex, and the presence of ascarids or the number of ascarids. Cryptosporidium spp. oocysts and Giardia spp. cysts were detected in 11/44 (25%; 95% CI: 13.2, 40.3) and 3/44 (6.9%; 95% CI: 1.4, 18.7) raccoons, respectively. The genotype of the Giardia present could not be determined. The genotype of five of six cryptosporidial isolates was 100% homologous to the skunk genotype while the sixth was 100% homologous to Cryptosporidium parvum. Based on these results, both B. procyonis and Cryptosporidium spp. appear to be prevalent in raccoons of eastern Colorado.     

Cerebrospinal nematodiasis in pheasants

Infection with larvae of Baylisascaris procyonis, the raccoon ascarid, was the cause of neurologic disease affecting young pheasants on a commercial pheasant ranch in Wisconsin. The disease was chronic and insidious, affecting 1% to 2% of the birds over a period of 2 years. Histologic lesions in the brain consisted of multifocal areas of necrosis and inflammation associated with Baylisascaris larvae. Onset of the disease at the farm correlated with introduction of chopped straw as bedding for the young birds. The straw was from a neighbor's barn and was contaminated with raccoon feces that contained B procyonis eggs. Cessation of use of the contaminated straw resulted in cessation of CNS disease in pheasants on the ranch.     

Visceral and presumptive neural baylisascariasis in an orangutan (Pongo pygmaeus).

A 32.5-year-old female hybrid orangutan (Pongo pygmaeus) developed hind-limb stiffness that progressed to tetraparesis over 2 wk. Repeated diagnostic evaluations, including serial magnetic resonance imaging of the central nervous system, revealed nonspecific lesions involving both the deep white and gray matter with an intact blood-brain barrier. Multiple empirical treatments failed to produce improvement and the animal was humanely euthanized. Histology of a granuloma in the ileum contained a nematode parasite, most consistent with Baylisascaris procyonis. Additionally, neuropil vacuolization, rarefaction, astrocytic scarring, and an eosinophilic granuloma and lymphoeosinophilic perivascular cuffing in the brain were suggestive of nematode migration. These findings confirm the presence of visceral larval migrans and support the presence of neural larval migrans. This case report of Baylisascaris procyonis confirms the presentation for the first time in an ape and documents the difficulty in antemortem diagnosis of neural larval migrans.     

Intestinal parasites of raccoons (Procyon lotor) from southwest British Columbia.

This is the first extensive survey of metazoan parasites (particularly of the roundworm Baylisascaris procyonis) from the intestines of raccoons in British Columbia. The sample collected in 1997-1998 consisted of 82 raccoons that had been sick or had been killed accidentally by automobiles. Fifteen parasite taxa were found: 3 nematodes, 9 digenetic trematodes, 2 acanthocephalans and 1 cestode. Ten of these parasites constitute new host records for raccoons, including 4 digenetic trematodes that have been reported in marine birds and mammals on the Pacific Coast of North America. Baylisascaris procyonis infected 61% of the raccoons with a mean intensity of 27. The high rate of infection indicates a large potential for environmental contamination and, thus, human and animal exposure to infectious eggs. Prevention of larva migrans is discussed, particularly for people in contact with raccoons in wildlife rehabilitation centers.     

Experimental infection of domestic swine with Baylisascaris procyonis from raccoons

Six 8-week-old ascarid-naive pigs which were experimentally infected with 72,000 embryonated Baylisascaris procyonis eggs of raccoon origin developed lesions limited to the intestines and liver. Intestinal lesions consisted of multifocal areas of inflammation by macrophages, eosinophils, and lymphocytes in the mucosa and submucosa, in association with Baylisascaris larvae; similar lesions were seen in the mesenteric lymph nodes. Typical white, granulation type, multifocal interstitial hepatitis ("milk-spots"), 1 to 5 mm in diameter, were seen in the livers by 7 days, with resolution by 47 days. Microscopically, these consisted of multifocal areas of marked periportal and interlobular edema, and influx of eosinophils, and large intralobular aggregates of eosinophils. At 47 days, hundreds to thousands of small white granulomas were seen on the serosa of the intestines; microscopically, they were discrete collections of macrophages, lymphocytes, and eosinophils in the submucosa and muscle layers surrounding nonviable remnants of Baylisascaris larvae. Larvae or lesions were not seen in other tissues, including the brain. These experiments indicated that B procyonis will undergo limited migration in swine and can produce typical white spots in the liver. The larvae were killed by cellular reactions in the intestinal wall and liver, and, unlike the situation in most other animals infected with this parasite, no somatic migration or CNS disease occurred after infection.     

Polioencephalomalacia in captive harbour seals (Phoca vitulina)

In a colony of 11 harbour seals (Phoca vitulina Linné 1758) two episodes of central nervous disorders occurred within 2 years causing fatalities in seven adult animals. Clinical signs comprised dyspnoea, anorexia, apathy, incoordination and lateral recumbency. Vitamin B complex therapy was successful once. Pathomorphological examination of seven carcasses revealed acute and subacute malacia of the cerebellar grey matter. Additional acute malacic lesions located in the cerebral cortices and basal ganglia were observed. Mesencephalic nuclei were less severely affected and displayed acute changes. Despite intense search for environmental toxins and infectious agents, the cause of the fatalities remained undetermined. However, the type and pattern of the lesions are most suggestive of a thiamine deficiency.     

棕熊蛔虫ITS rDNA的PCR扩增与序列分析

目的以核糖体DNA（rDNA）的第一与第二内转录间隔区序列（ITS-1及ITS-2）鉴定从广州动物园棕熊分离的蛔虫种类。方法应用PCR方法以保守引物NC5和NC2扩增蛔虫样本的ITS及5．8SrDNA序列,将PCR扩增出的片段纯化后克隆至pGEM-TEsay载体,用菌落PCR及酶切鉴定阳性菌落,对阳性菌落进行测序,并与Gen．Bank“公布的人蛔虫（Ascaris lumbricoides）、猪蛔虫（Ascariis suum）、浣熊贝利斯蛔虫（Baylisascaris procyonh）及狮弓蛔虫（Toxascaris leonina）ITS序列比较。结果从棕熊分离的2个蛔虫样本的ITS及5．8SrDNA总长为859—861bp,种内相似性为99．7％,与GenBank^TM公布的人蛔虫、猪蛔虫、浣熊贝利斯蛔虫及狮弓蛔虫的相似性分别为84．6％、84．5％、89．3％及72．3％,序列差异明显。结论棕熊蛔虫不同于上述种类蛔虫,可能为Baylisacaris transfuga.     

Fatal cerebrospinal disease caused by Baylisascaris procyonis in domestic rabbits

Infection with Baylisascaris procyonis, the common roundworm of raccoons, was found to be the cause of an epizootic of fatal CNS disease in domestic rabbits (Oryctolagus cuniculus). Clinical signs included torticollis, ataxia, tremors, and falling. Gross lesions were limited to white, raised nodules (1 to 1.5 mm) on the epicardium, endocardium, and liver serosa, and they were found to be larval granulomas. Microscopic lesions included multifocal myocarditis, multifocal hemorrhagic tracks and associated necrosis and inflammation in the liver, multifocal eosinophilic myositis, focal nephritis, and mild interstitial pneumonia; larval granulomas were seen in the heart, liver, lung, and mandibular salivary gland. Lesions in the brain consisted of multifocal areas of necrosis and inflammation in the cerebrum, cerebellum, midbrain, and medulla, with accompanying perivascular leukocyte aggregates and neuronal and axonal degeneration. Large numbers of large ascarid larvae were seen in the brain. Epidemiologically, infection was linked to the use of contaminated straw from a barn used by raccoons. On the basis of this study as well as that of similar studies, it was concluded that barn use and contamination by raccoons may be an important source of infection of animals and possibly man with this parasite.     

Application of western blotting procedure for the immunodiagnosis of visceral larva migrans in mice by using excretory/secretory antigens

A Western blotting procedure with excretory/secretory antigens from Toxocara canis larvae was developed for immunodiagnosis of visceral larva migrans in mice. In this study, eighty Swiss albino mice were allotted into two groups of 40 each as control and experimental groups, and T. canis ova containing infective larvae were given to mice in the latter group to form visceral larva migrans. Blood samples were taken from 5 infected and 5 control mice on days 25, 30, 35, 40, 45, 50, 55, and 60 after infection. After bleeding, the mice were necropsied. Slides were prepared from their brain tissues and examined for visceral larva migrans. Following this procedure, their guts were also examined for intestinal parasites. Protein bands of excretory/secretory antigens of 2nd stage larvae of Toxocara canis were determined by using SDS-PAGE. Sera from the mice were tested by Western blotting and results were compared to the protein bands obtained by SDS-PAGE to determine specific bands. Specific protein bands for visceral larva migrans were determined as 24, 28, and 48 kDa according to our test results.     

Experimental Toxocara canis infection in cynomolgus macaques (Macaca fascicularis)

Visceral larva migrans was produced in 16 cynomolgus macaques (Macaca fascicularis) experimentally inoculated with 45,000 embryonated eggs of Toxocara canis as a single bolus or in 3 divided doses. The hematologic and serologic changes were similar to those observed in children with visceral Toxocara infection. Neurologic signs developed in 3 animals and were characterized by ataxia and nystagmus. Growth rates were diminished in inoculated animals when compared with the rates in noninoculated controls. Diagnostic antibody titers as measured by enzyme-linked immunosorbent assay were noted in all inoculated macaques by the 4th week, and these titers persisted during the 7-month period of observation. Antibody to Toxocara was not detected in the aqueous or vitreous humors. Lesions comprised severe granulomatous hepatitis and encephalomyelitis. Intraocular lesions associated with larval migration were not observed.     

小熊猫蛔虫ITS及5.8S rDNA序列的克隆与分析

以广州动物园小熊猫体内分离出的蛔虫为研究对象,运用PCR方法,以保守引物NC5和NC2扩增其核糖体DNA（rDNA）的内转录间隔区（ITS）和5.8S序列,并对扩增后的片段进行纯化、克隆至pGEM-Teasy载体、转化、测序和序列分析,以鉴定小熊猫蛔虫的种类。结果显示2条蛔虫样品的ITS及5.8S rDNA序列基本一致,总长为913 bp,样品间序列相似性为99.7%。将序列与GenBank^TM公布的相关序列进行比较分析,结果显示2条蛔虫的ITS及5.8S序列与黑熊横走贝蛔虫（Baylisascaris transfuga注册号AB571304）相似性分别为98.1%、98.4%,与大熊猫西氏贝蛔虫（Baylisascaris schroederi注册号JN210912）相似性分别为96.9%、97.1%,与猪蛔虫（Ascaris suum注册号AB571302）相似性分别为89.9%、90.1%,与人蛔虫（Ascaris lumbricoides注册号AB571296）相似性分别为89.8%、90.1%,ITS-1序列与浣熊贝蛔虫（Baylisascaris procyonis注册号AB053230）相似性分别为92.0%、92.3%。研究结果表明小熊猫体内分离的蛔虫可能为贝蛔属蛔虫,从而为蛔虫的进一步分类、鉴定和遗传变异研究奠定了基础。     

Circulation of Toxocara spp. in suburban and rural ecosystems in the Slovak Republic

Toxocara spp., the common roundworms of domestic and wild animals, are the causative agents of larval toxocarosis in humans. The migration of Toxocara larvae in men causes clinical syndrome, called larva migrans visceralis or larva migrans ocularis. The objective of the present work was to investigate the prevalence of toxocarosis in dogs, red foxes (Vulpes vulpes), and small mammals in the Slovak Republic. T. canis infection was diagnosed in 16.6% out of 145 dogs examined. Young animals showed significantly higher positivity (50.0%) than adults (12.4%). Coprological investigation of 310 red foxes showed 8.1% prevalence of T. canis, with higher occurrence in animals from rural conditions (8.6%) than from suburban environment (5.6%). Out of 710 small mammals examined, anti-Toxocara antibodies were detected in 7.7% of the animals. The most frequently seropositive species was Apodemus agrarius (15.9%). Seropositivity of small mammals from suburban localities was higher (10%) compared with rural areas (5.8%), with adult animals exhibiting higher seropositivity (8.0%) than subadults (6.8%). Our results have confirmed the importance of dogs, red foxes and small mammals in circulation of this serious helminthozoonosis in suburban and rural ecosystems.     

Sheep oestrosis (Oestrus ovis Linné 1761, Diptera: Oestridae) in Sardinia, Italy.

Oestrosis, the nasal myiasis of sheep and goats, is caused by the larvae of Oestrus ovis L. 1758 (Diptera, Oestridae) that develop from the first to the third stage larva in the nasal cavities and frontal sinuses of affected animals. The authors report the results of an epidemiological study of oestrosis of sheep in Sardinia, Italy. Heads of 6-month to 10-year-old Sardinian sheep (n=566) from 124 free-ranging flocks were examined for the presence and location O. ovis larvae from December 1996 to November 1997. Larvae were collected, counted, and larval stages were identified. O. ovis larvae were found in 100% of examined flocks and in 91% (514/566) of examined sheep. The monthly prevalence ranged from 69% in May to 100% in July. First stage larvae were found in 82% (463) of all heads examined, second stage larvae in 65% (367) and third stage larvae in 10% (56). The majority of sheep harboured first stage larvae, with prevalences of over 80% throughout most of the study period. The prevalence of O. ovis found in this study of Sardinian sheep is the highest reported in the Mediterranean area. The high percentage of first stage larvae found throughout the entire study period may be due to a brief period of decreased rate of larval maturation, in particular in December 1996 (96%) and January-October 1997 (94%). Third stage larvae were consistently present, often however, with extremely low prevalences compared to total larval burden.     

Ascarid infections of cats and dogs

The ascarids Toxocara canis, Toxocara cati, and Toxascaris leonina are probably the most common gastrointestinal helminths encountered in small animal practice. Both T. canis and T. cati can cause serious disease in kittens and puppies; T. leonina is generally less pathogenic. Prenatal transmission assures that virtually all puppies are born infected with T. canis. Transmammary transmission is probably the major route of infection for kittens with T. cati. In addition, all three species of worm produce resistant eggs and use paratenic hosts to facilitate transmission. Much is now known about the complex biology and life history of T. canis. However, many questions, such as those concerning the mechanisms of larval survival within host tissues and of larval reactivation and migration during pregnancy, await further study. The mechanism of resistance to ascarid infections in cats and dogs has not been clearly defined. Ascariasis is traditionally thought to be a disease of young animals, with older animals being considered immune. However, at least in the case of T. canis, adult dogs can be repeatedly infected. A wide range of anthelmintics is available with extremely high efficacy against patent ascarid infections. The problem of prenatal infection with T. canis may be overcome by strategic use of the newer benzimidazole-carbamates, and the production of ascarid-free puppies now seems possible. However, complete larvicidal activity against somatic stages has not been convincingly demonstrated. Visceral larva migrans-like syndromes are now being recognized in dogs and cats. In addition, visceral larva migrans in children due to T. canis continues to be a significant zoonotic disease in North America and underscores the need for the veterinary profession to control ascarid infections in cats and dogs at every opportunity.     

Visceral larva migrans and alveolar hydatid disease. Dangers real or imagined.

For both visceral larva migrans and alveolar hydatid diseases, it is the feces of companion animals that are the primary source of human infection. Clearly, whatever is done to reduce this form of environmental contamination and the prevalence of the parasites' infective stages will help to protect the health of the human population in the United States and Canada, particularly the children. Very important are appropriate anthelmintic treatment programs, especially for T. canis, and proper control of close associations between pets and people. Probably the known incidence of visceral larva migrans in humans and the range of its known pathogenicity will increase as better diagnostic methods become available. In addition, other animal helminths, for instance Toxocara cati and Toxascaris leonina, may become more substantially documented as causes of human visceral larva migrans. Until more is known of the geographical distribution and prevalence of Echinococcus multilocularis among animals in North America, it will be difficult to assess accurately the future significance of alveolar hydatid disease in the continent's human population. Another important advance would be the development of anthelmintics that are effective for somatic second stage larvae of T. canis, and others effective for adult or larval Echinococcus species. Meanwhile it is a most important responsibility of the veterinary profession to educate its clients thoroughly concerning these dangerous helminths.     

Baylisascaris procyonis encephalitis in Patagonian conures (Cyanoliseus patagonus), crested screamers (Chauna torquata), and a western Canadian porcupine (Erethizon dorsatum epixanthus) in a Manitoba zoo

Neurological disease occurred in 4 Patagonian conures (Cyanoliseus patagonus), 2 crested screamer chicks (Chauna torquata), and 1 western Canadian porcupine (Erethizon dorsatum epixanthus) at a Manitoba zoo. Baylisascaris procyonis, the common raccoon roundworm, not previously identified in Manitoba, is considered the likely cause of neural larval migrans in these cases.     

Effect of glucan preparation on immunocompetent cells and phagocytic ability of blood leucocytes in experimental ascariosis of pigs.

In experimental ascariosis (Ascaris suum) of pigs a preparation of glucan combined with pig immunoglobulin and zinc was found to significantly elevate the levels of both T and B lymphocytes in the blood, and to significantly stimulate the phagocytic ability of monocytes and neutrophilic granulocytes in experimental pigs. The protective effect of the preparation, assessed by the reduction in the number of migrating ascarid larvae in the lungs of pigs was 65%.