Aspects of the life cycle and pathogenesis of Elaphostrongylus alces in moose (Alces alces).

Aspects of the migratory life cycle and pathogenesis of Elaphostrongylus alces were studied in 7 randomly selected moose calves and 7 yearlings killed during August to November. One calf and 1 yearling were uninfected. The 6 infected calves had recent infections, whereas the 6 yearlings showed older infections from the summer of the previous year. The 2 calves killed in September had a total of 26 adult E. alces in the epidural space of the caudal vertebral canal and none in the skeletal muscles, whereas the remaining calves killed 1 to 2 mo later had 25 nematodes in the caudal and cranial vertebral canal and 7 in the skeletal muscles. The yearlings had a total of 101 adult E. alces in the skeletal muscles and 2 in the vertebral canal. There were no findings indicating involvement of the central nervous system in the life cycle of E. alces. Our findings suggest that E. alces migrates directly from the gut to the epidural space of the caudal vertebral canal where development to the adult stage takes place. During development, the nematode produces inflammation of the epidural tissue and spinal nerves. Development in the caudal vertebral canal is followed by some anterior dispersion of nematodes along the canal, and migration into skeletal muscles. Here the nematodes seem to live in reproductive pairs and groups. The predilection site for E. alces in moose is the muscles of the thigh.     

The Prevalence of Elaphostrongylus Cervi Infection in Moose (Alces alces) in Southern Norway

The prevalence of Elaphostrongylus cervi infection in moose shot during the hunting season 1983 in 47 different municipalities in Southern Norway was studied. E. cervi seemed to occur endemically in the population, as infection was found in 35 % of 1,982 moose examined. Diagnosis was made on the basis of the presence of eggs and first-stage larvae (L1) and associated histopathological lesions in the lung, and on the presence of L1 in the faeces. The prevalence varied considerably between different municipalities. No relationship was found between the prevalence of E. cervi and the population density of moose. The highest prevalence was found in municipalities where red deer harbouring E. cervi were also present. The prevalence among males was higher than among females, and that among yearlings higher than among calves and adults. In no case was infection found in animals 51/2 years of age or older. Carcass weight in infected adult moose was significantly lower than in non-infected adults.     

Larvae of Elaphostrongylus cervi in a population of free-living red deer in Italy

Hunter-killed red deer (n = 68; Cervus elaphus) harvested from the Italian provinces of Bologna (Emilia Romagna) and Pistoia (Tuscany) (44 degrees 00'N 11 degrees 00'E) from October 2001 to January 2002 were examined for protostrongylid larvae. Twenty-eight animals (41%) had protostrongylid larvae in feces, lungs, and inguinal and iliac lymph nodes. Of these 28 animals, 20 were adults (71%), four were yearlings (14%), and four were calves (14%). Shape, length, width, and the location to the nematodes were consistent with Elaphostrongylus cervi, which has not been previously reported in Italy.     

Cerebrospinal nematodiasis in a moose in Norway

A case of cerebrospinal nematodiasis in a young adult moose (Alces alces) from Telemark county, southeastern Norway, is described. The moose was found by bird hunters during January, displaying signs of severe posterior paresis. It was killed and submitted for autopsy. The carcass was emaciated, and there were skin excoriations and subcutaneous edema over both metacarpi. Histopathologic examination revealed traumatic malacia throughout the spinal cord and meningeal accumulations of mononuclear inflammatory cells and eosinophils in brain and spinal cord. Two adult female nematodes were found in sections, respectively, of the subarachnoid and subdural spaces of the thoracic spinal cord. The nematode cross sections were similar with those of the two neurotropic Elaphostrongylus species, E. rangiferi and E. cervi. The moose originated from an area overlapping the grazing area of a large population of wild reindeer (Rangifer tarandus tarandus) living on the mountain plateau of Hardangervidda, suggesting the moose was infected with E. rangiferi from reindeer.     

Identification of antigens with potential for immunodiagnosis of Parelaphostrongylus tenuis and Elaphostrongylus cervi infections in red deer (Cervus elaphus elaphus)

Red deer (Cervus elaphus elaphus) were infected experimentally with Parelaphostrongylus tenuis in New Brunswick, Canada, and with Elaphostrongylus cervi in New Zealand. Excretory-secretory (E-S) antigens from adult P. tenuis were evaluated for their serodiagnostic potential in identifying P. tenuis and heterologous E. cervi infections in a Western blot. The antigen recognition profile of sera from animals infected with P. tenuis varied between individuals and with duration of infections, whereas that of pooled sera from animals infected with E. cervi showed less variation. A single molecule of 42-43 kDa was recognized consistently by sera from all animals infected with either P. tenuis or E. cervi. Sera from unexposed control deer and from those with other heterologous nematode infections did not consistently identify this antigen. Serorecognition of the 42-43-kDa antigen by deer infected with P. tenuis resulted in a sensitivity of 99% and a specificity of 85% (> or =1 mo postinfection). Although antibody to this antigen waned with time, the persistence of recognition up to 34 mo postinfection with P. tenuis exemplifies its diagnostic value. The sensitivity and specificity of diagnosis using this molecule were each 100% for identifying deer infected with E. cervi (> or =3 mo postinfection). Two other molecules from E-S of adult P. tenuis, 26-28 and 10-12 kDa, were also diagnostic, although their recognition was not persistent throughout infections. These 2 molecules may prove useful in combination with the 42-43-kDa antigen to help identify all infected animals during all phases of infections. This research represents the first conclusive identification of antigens with real potential for reliable antemortem immunodiagnosis of both P. tenuis infections and heterologous E. cervi infections.     

Elaphostrongylus cervi in a population of red deer (Cervus elaphus) and evidence of cerebrospinal nematodiasis in small ruminants in the province of Varese, Italy

Thirty-one faecal samples were collected from red deer in the northern area of Varese, in the Italian region of Lombardy, between August and October 2008. The animals had either been hunted or accidently killed. Examination for internal parasites showed a prevalence of 45.2% for Elaphostrongylus cervi larvae and species identification was confirmed by polymerase chain reaction (PCR). Ninety-seven faecal samples were also collected from two goat flocks grazing in the same area between December 2007 and May 2008. These showed a prevalence of 74.7% for lungworms. Furthermore, the central nervous systems from five goats and one sheep from this area with a history of neurologically related lameness were examined. Histopathology confirmed E. cervi cerebro-spinal nematodiasis in five cases out of six. This study demonstrates E. cervi transmission from wild to domestic ruminants when the animals graze in the same area, and the possible occurrence of clinical disease in infected goats and sheep associated with high prevalence in deer.     

Nervous Tissue Lesions Caused by Elaphostrongylosis in Wild Swedish Moose

During the first 5 months of 1985, 35 moose were obtained for necropsy at the National Veterinary Institute, Uppsala, Sweden. 17 (49 %) of these cases were found to be infected with Elaphostrongylus sp. The nematodes were found in the epidural space of the spinal cord and brain, around and in the sciatic nerves and in muscle fasciae. Predilection sites appeared to be near cauda equina and the fasciae of the thoracic, gracilis and sartorius muscles. Most of the infected animals were calves. Both sexes were equally represented. Pathological changes found were characterized by focal haemorrhages and oedema. The changes were present in the muscle fasciae and in the leptomeninges of the brain and spinal cord. Beside infiltrates of mainly lymphocytes and plasma cells, adult nematodes, larvae and eggs were observed. Cases with mild gliosis in the cerebrum and degenerative changes of peripheral nerve roots affecting the epi- and perineurium were also found. In one case the inflammatory changes reached the endoneurium of a sciatic nerve bundle and in another case into a ganglion. Inflammatory reactions against the parasite were mainly directed towards eggs. In loose connective tissue close to nerve tissue in the central nervous system larvae were found close to eggs and remains of eggs indicating that eggs may hatch at this site. This investigation shows that natural infections with Elaphostrongylus sp. occur in wild moose and may produce pathological changes in large peripheral nerves and in the central nervous system.     

Susceptibility of Amblyomma americanum to natural and experimental infections with Theileria cervi

One hundred fifty Amblyomma americanum were examined between March and September 1986 from Cookson Hills Wildlife Refuge in eastern Oklahoma (USA). Of these ticks, 11% (17 of 150) were infected with Theileria cervi. Field-collected nymphal ticks had an 8% (3 of 37) prevalence of infection averaging 1.0 infected acini/nymph. Female ticks had a 16% prevalence of infection averaging 1.6 infected acini/female; T. cervi was not observed in salivary glands of field-collected male ticks. When laboratory reared A. americanum nymphs were allowed to feed on experimental white-tailed deer (Odocoileus virginianus) with varying T. cervi parasitemias (less than 1, 2, 6 and greater than 20%), only ticks which fed on deer with parasitemias greater than 1% became infected. Although prevalence and intensity of infection varied in the infected ticks, there was no significant difference in prevalence of infection between males and females. However, females did acquire significantly greater intensities than males. The data from these studies confirm that T. cervi overwinters in A. americanum and suggests that the prevalence, intensity and abundance of infection of T. cervi in ticks is influenced by the parasitemia of the deer host. Furthermore, fawns may play a more important role in the epidemiology of T. cervi transmission than do adult deer because of the coordination between tick activity patterns and deer fawning.     

Prevalence of Muellerius capillaris in free-ranging spotted deer (Cervus axis) in India and its experimental cross-transmission to goats

A survey to assess the prevalence of parasitic infections among axis deer (Cervus axis) in three National Parks in India revealed infections with the lungworm Muellerius capillaris. Clinical signs were not evident in infected animals. Therefore, it is suggested that C. axis is probably a carrier of the infection. Under laboratory conditions, terrestrial molluscs (Macrochalamys sp.) were infected with first stage larvae of M. capillaris collected from fecal pellets of C. axis. Feeding of third stage larvae collected from these snails on day 14 post exposure produced patent infections in goats. On day 31 post infection, adult M. capillaris could be collected from the lungs of infected goats. This study establishes the possibility of cross-transmission of M. capillaris between wild and domestic animals in India.     

Factors influencing the infectivity of a Canadian isolate of Steinernema kraussei (Nematoda: Steinernematidae) at low temperature

The effectiveness of Canadian isolate 76 of Steinernema kraussei, at 10 degrees C, in penetrating Galleria mellonella larvae (percentage parasitism and number of IJs developed to adult nematodes) was measured at different host densities (differing number of larvae and size of experimental arena) and for different durations of exposure. The greater the size of the inoculum of infective juvenile nematodes per unit area and the longer the duration of exposure, the greater the number of larvae that were killed and the larger the number of mature nematodes in the larval host. The infection rate (alpha) and the adjusted infection rate (beta) were determined using the modified Anderson model. This model successfully described the behavior of the S. kraussei-G. mellonella interaction.     

Migration behaviour and pathogenesis of five ascarid nematode species in the Mongolian gerbil Meriones unguiculatus

To understand the characteristic features of the Mongolian gerbil, Meriones unguiculatus, as an animal model of ascarid infections, the migration behaviour and pathogenesis of larvae were investigated in experimentally infected gerbils. Embryonated eggs from each of Toxocara canis, Baylisascaris procyonis, B. transfuga, Ascaris suum, and A. lumbricoides were orally inoculated into gerbils and larvae were recovered from various organs at designated periods. In T. canis-infected gerbils, larvae were present in the liver 3 days after infection and in the skeletal muscle and brain via the heart and lungs at a similar rate. In B. procyonis- and B. transfuga-infected gerbils, larvae were present in the lungs within 24 h after infection, with some having reached the brain by that time. After 24 h, larvae of B. procyonis tended to accumulate in the brain, while those of B. transfuga accumulated in skeletal muscles. In A. suum- and A. lumbricoides-infected gerbils, larvae remained in the liver on day 5 post-infection and elicited pulmonary haemorrhagic lesions, which disappeared 7 days after initial infection. Thereafter, no larvae of any type were recovered. Ocular manifestations were frequently observed in T. canis- and B. procyonis infected gerbils, but were rare in B. transfuga-infected gerbils. In the cases of A. suum and A. lumbricoides, migration to the central nervous system and eyes was extremely rare, and larvae had disappeared by 2 weeks post-infection. Fatal neurological disturbances were observed in B. procyonis-infected gerbils, whereas irreversible non-fatal neurological symptoms were observed in the case of B. transfuga.     

Evidence of prenatal infection in the bottlenose dolphin (Tursiops truncatus) with the lungworm Halocercus lagenorhynchi (Nematoda: Pseudaliidae)

Adult lung nematodes identified as Halocercus lagenorhynchi were collected from the lungs of four Tursiops truncatus calves. The calves ranged in age from newborn to 3-wk-old and were found on both the Atlantic and Gulf coasts of Florida (USA). This finding suggests the possibility of a more cosmopolitan distribution of prenatal infection with lung nematodes in cetaceans than previously suspected.     

Developmentally regulated expression of the mouse homologues of the potassium channel encoding genes m-erg1, m-erg2 and m-erg3

Deciphering the expression pattern of K+ channel encoding genes during development can help in the understanding of the establishment of cellular excitability and unravel the molecular mechanisms of neuromuscular diseases. We focused our attention on genes belonging to the erg family, which is deeply involved in the control of neuromuscular excitability in Drosophila flies and possibly other organisms. Both in situ hybridisation and RNase Protection Assay experiments were used to study the expression pattern of mouse (m)erg1, m-erg2 and m-erg3 genes during mouse embryo development, to allow the pattern to be compared with their expression in the adult. M-erg1 is first expressed in the heart and in the central nervous system (CNS) of embryonic day 9.5 (E9.5) embryos; the gene appears in ganglia of the peripheral nervous system (PNS) (dorsal root (DRG) and sympathetic (SCG) ganglia, mioenteric plexus), in the neural layer of retina, skeletal muscles, gonads and gut at E13.5. In the adult m-erg1 is expressed in the heart, various structures of the CNS, DRG and retina. M-erg2 is first expressed at E9.5 in the CNS, thereafter (E13.5) in the neural layer of retina, DRG, SCG, and in the atrium. In the adult the gene is present in some restricted areas of the CNS, retina and DRG. M-erg3 displayed an expression pattern partially overlapping that of m-erg1, with a transitory expression in the developing heart as well. A detailed study of the mouse adult brain showed a peculiar expression pattern of the three genes, sometimes overlapping in different encephalic areas.     

A contribution to the study of acute schistosomiasis (an experimental trial)

In an attempt to establish an experimental model of acute schistosomiasis, sequential histological changes were investigated in the skin, lung, liver and spleen of mice infected with 30 or 100 cercariae of Schistosoma mansoni according to four sets of experiments: single infection, repeated infections, unisexual infection and infection in mice born from infected mothers. Animals were killed every other day from exposure up to 50 days after infection. Only mild, isolated, focal inflammatory changes were found before the appearance of mature eggs in the liver, even when repeated infections were made. Severe changes of reactive hepatitis and splenitis appeared suddenly when the first mature eggs were deposited, around the 37th to 42nd day after infection. The mature eggs induced lytic and coagulative necrosis of hepatocytes around them which was soon followed by dense infiltration of eosinophils. So, mature egg-induced lesions appeared as the major factors in the pathogenesis of acute schistosomiasis in mice. Mice born from infected mothers were apparently able to rapidly modulate the egg-lesions, forming early fibrotic granulomas. The murine model of acute schistosomiasis appeared adequate for the study of pathology and pathogenesis of acute schistosomiasis.     

The effects of Ureplasma diversum inoculated into the amniotic cavity in cows

Ureaplasma diversum was inoculated into the amniotic cavity in four cows. Two calves were aborted and two were born alive. One of the latter died shortly after birth and the other was killed. The cows remained clinically normal except that three retained their placenta. On microscopic examination there was a severe placentitis and an alveolitis was present in the lungs of all calves. Ureaplasma was recovered from four placentas and three lungs. Cows remained infected for a maximum of 132 days following inoculation and the organism was recovered in urine and vulvar swabs for a maximum of 17 and 60 days respectively following expulsion of the calf. Ureaplasma diversum has been isolated from natural cases of abortion with similar lesions. This experiment strongly supports a causal relationship between abortion, birth of calves with pneumonia and U. diversum infection.     

Assessment of domestic goats as a patent host of Elaphostrongylus cervi

A study was undertaken to determine whether domestic goats can serve as patent hosts of Elaphostrongylus cervi under natural or experimental conditions. Three-hundred and two fecal samples from 124 domestic goats raised outdoors in New Zealand, where E. cervi is enzootic, were tested for nematode larvae by the Baermann method. All samples were negative for E. cervi dorsal-spined larvae. Twenty juvenile male Nubian and Saanen goats obtained locally were assigned randomly to 5 dosage groups and were orally administered 5, 15, 35, 65, or 125 third-stage larvae of E. cervi, respectively. Two yearling female red deer (Cervus elaphus elaphus) each received 35 or 65 third-stage larvae as positive controls, and 2 uninoculated juvenile male goats served as negative controls. Fecal Baermann testing of pooled samples from the inoculated goats was conducted weekly for the first 80 days postinoculation (DPI) and daily thereafter until 250 DPI. No dorsal-spined larvae were recovered. One goat that had received 15 third-stage larvae displayed a mild transient posterior ataxia suggestive of cerebrospinal elaphostrongylosis. Gross postmortem examination did not reveal any direct evidence of nematodes in any of the goats, and only a few minor lesions were present. Histologically, these lesions were consistent with a parasite etiology. Histological evaluation of grossly normal lumbar and sacral spinal cord from 2 goats that had each received 125 third-stage larvae revealed eosinophilic meningoencephalitis and leukomyelitis, respectively, suggestive of the presence of parasites in the central nervous system. The 2 positive control red deer became patent with dorsal-spined larvae consistent with E. cervi at 131 DPI. These findings suggest that goats, at least those breeds utilized in this study, are not suitable patent hosts for E. cervi.     

Elaeophorosis in bighorn sheep in New Mexico

Two bighorn sheep (Ovis canadensis) in New Mexico (USA) were found to be naturally infected with Elaeophora schneideri. An adult ram examined in 1997 in the Fra Cristobal Mountains had 26 nematodes in the carotid and iliac arteries, and microfilariae were present in the skin, nasal mucosa, brain, and lungs. This ram was markedly debilitated prior to euthanasia and extensive crusty, scabby lesions were observed on its head. In 1998, a yearling ewe found dead adjacent to Watson Mountain near the Gila Wilderness area was found to have 13 nematodes present in its heart. This is the first report of E. schneideri in bighorn sheep, and we suggest that bighorn sheep are susceptible to E. schneideri infection wherever they coexist with mule deer (Odocoileus hemionus hemionus) and appropriate tabanid vectors.     

Epidemiology of cerebrospinal Elaphostrongylus cervi infection in red deer in central Spain

Elaphostrongylus cervi produces a subclinical cerebrospinal disease in many wild and domestic ruminants from Europe, North America and New Zealand and has recently been described in Spain. To determine some aspects of its epidemiology, 121 red deer (Cervus elaphus) from central Spain were sampled during 2000. The prevalence (7%) and mean worm burden (3.8 worms per brain) were similar to the values previously recorded in other European areas. The infection was only detected in young deer during the winter. The estimation of larval production in the faeces was not a reliable method of diagnosing E. cervi infection.     

Nucleopolyhedrovirus infected central nervous system cells of Bombyx mori (L.) (Lepidoptera: Bombycidae)

BmMNPV, a Nucleopolyhedrovirus isolated from infected Bombyx mori (L.) larvae in Paraná State--Brazil, was used to inoculate healthy 5th-instar B. mori larvae and examine the infection on central nervous system (CNS) cells. Samples of nervous tissue were removed from the infected insects, at different sampling times, and processed for cytopathology studies by light and transmission electron microscopy using routine techniques. The experiment included both inoculated and non-inoculated larvae (control). BmMNPV infection was detected on the 5th day after inoculation in CNS cells. Initially, infection was characterized by nuclear hypertrophy and the presence of virogenic stroma, in which the progeny virions were produced. Virions are enveloped and occluded into protein crystal, the polyhedra. Lyses of infected CNS cells were undetected; however, free mature polyhedra were seen in spaces inside the CNS. These polyhedra possibly came from trachea that penetrate the CNS and its cells, which are susceptible to BmMNPV and lyses after infection. We conclude that the tracheal system is responsible for disseminating BmMNPV infection in B. mori CNS and that the tracheal branches allow non-occluded virions to pass through the blood-brain barrier.     

First report of Elaphostrongylus cervi in Spanish red deer Cervus elaphus hispanicus

Elaphostrongylus cervi Cameron, 1931 was identified in six Cervus elaphus hispanicus sampled in Cuenca, central Spain. A total of 23 adult worms were found in the central nervous system with a mean of 3.8. Although E. cervi is reported to be widespread in cervids, this is the first time it has been recorded in Spanish red deer.