Search

Dimensions and illustrations of the first-, second-, and third-stage larvae of Elaphostrongylus alces are presented for the first time. First-stage larvae were 417 ± 16 µm long (mean ± SD) (range 377-445 µm) and similar in size to those of E. cervi (420 ± 13 µm long; range 392-445 µm) and E. rangiferi, the other recognized members of the genus. The mean length of third-stage E. alces larvae (714 ± 23 µm long; range 675-756 µm) recovered from gastropod intermediate hosts was significantly less than that of E. cervi (831 ± 78 µm long; range 669-954 µm) and E. rangiferi, providing further evidence of the distinct status of E. alces, a recently described species from moose in Fennoscandia.

The three species of the genus Elaphostrongylus occurring in Norway. namely, E. cervi, E. rangiferi and E. alces from Cervus elaphus, Rangijer tarandus and Alces alces respectively are redescribed and figured using light and scanning electron microscopical techniques. The taxonomic status of the three species is reviewed and their validity confirmed.

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.

Six reindeer (Rangifer tarandus), five sheep and six goats (Ovis ovis and Capra hircus) were experimentally infected with the nematode Elaphostrongylus alces. Additionally, one sheep was infected with E. rangiferi. Reindeer infected with E. alces showed no neurological signs. Sheep and goats infected with the same parasite also remained clinically healthy; however, the sheep infected with E. rangiferi showed severe neurological signs and became paralysed. Pathological lesions were minimal in reindeer and domestic ruminants infected with E. alces, but were prominent in the lamb infected with E. rangiferi. Our results indicate that keeping and transferring sheep and goats into ateas inhabited by moose, which is a natural host of E. alces may not harm the livestock, while keeping sheep in areas inhabited by reindeer infected with E. rangiferi may result in petiodic outbreaks of cerebrospinal elaphostrongylosis in sheep.

Moose ( Alces alces ) and reindeer ( Rangifer tarandus ) were experimentally cross-infected with Elaphostrongylus rangiferi and Elaphostrongylus alces , respectively. Both Elaphostrongylus species completed their development in the alternate hosts but produced fewer larvae than in their usual host species. Reindeer infected with Elaphostrongylus alces developed patent infections after 39–130 days. In moose, the prepatent period of this parasite was 39–73 days. Elaphostrongylus rangiferi infections were patent in moose after 133 days. The male morphological characteristics of E. alces in moose and reindeer, and E. rangiferi in moose and their migration pattern retained regardless of the host species. These results provide further evidence that E. alces and E. rangiferi are two distinct species.

Nematodes of the genus Elaphostrongyluscollected from moose (Alces alces L.), reindeer (Rangifer tarandus tarandus L.), and red deer (Cervus elaphus L.), respectively, were studied by means of scanning electron microscopy. Morphological differences in the ribs of the genital bursa were demonstrated. The Elaphostrongylus species from reindeer and red deer differed from each other in four ribs of the genital bursa. These results agree with the morphological characters of E. cervi and E. rangiferi described by Cameron (1931) and Mitskevitch (1960). The genital bursa of Elaphostrongylus sp. from moose, in accordance with the description of E. alces by Steen et al. (1989) showed characteristics differing from those found in Elaphostrongylus spp. from reindeer and red deer respectively. These results support the hypothesis that there are three separate species of Elaphostrongylus present in Scandinavian Cervidae. Svep-elektroniska studier på Elaphostrongylus spp. hos skandinaviska hjortdjur.Abstract in Swedish / Sammandrag: Rundmaskar inom slaktet Elaphostrongylus funna hos alg (Alces alces L.), ren (Rangifer tarandus tarandus L.) och kronhjort(Cervus elaphus L.) studerades med hjalp av svepelelektronmikroskop. De hanliga bursorna med sin a stodjeribbor uppvisade variationer i utseende, langd och placering mellan dessa rundmaskar. De arter av Elaphostrongylus funna hos ren och kronhjort skilde sig åt avseende fyra stodjeribbor på de hanliga bursorna. Dessa resultat stammer val overens med de karaktarer som tidigare ar beskrivna av Cameron(1931) och av Mitskevich (1960). Den hanliga bursan hos arten Elaphostrongylus funnen hos alg, vilken tidigare ar beskriven av Steen et al. (1989), visade upp ett utseende som skilde sig från bursorna hos de Elaphostrongylus-arter funna hos ren och kronhjort. Dessa resultat stoder hypotesen om tre skilda arter av Elaphostrongylus hos skandinaviska hjortdjur.

Six 1 year old female and 6 four months old male goats were inoculated different numbers of E. alces third-stage larvae. Protostrongylid larvae were not detected in the faeces of these animals during the experiment. At the end of the experimental period the animals were euthanized and autopsied. Neither parasites nor pathological lesions related to larval or adult stages of E. alces could be demonstrated.

A description of Elaphostrongylus alces n. sp., a parasite of moose (Alces alces L.), is given. The main features differing E. alces n. sp. from the other two investigated species are the bottle shaped oesophagus and the oval bursa, which is about 150 microns x 200 microns. E. rangiferi Mitskevith, 1960, a parasite of reindeer (Rangifer tarandus tarandus L.) and E. cervi Cameron, 1931, a parasite of red deer (Cervus elaphus L.) have both a club shaped or cylindrical oesophagus and a circular bursa. The bursa of E. rangiferi is about 160 microns in diameter, and the bursa of E. cervi is about 190 microns. Each species has been found only in its normal host.