4304.pdf ALCES VOL. 43, 2007 LANKESTER ET AL. - DIAGNOSING PARELAPHOSTRONGYLOSIS IN MOOSE 49 DIAGNOSING PARELAPHOSTRONGYLOSIS IN MOOSE (ALCES ALCES) Murray Lankester1,2, Wm. Peterson3, and Oladele Ogunremi4,5 1Retired, Professor Emeritus, Lakehead University, 955 Oliver Road, Thunder Bay, ON Canada P7B 5E1; 3Retired, Minnesota Department of Natural Resources, 4541 Lake Creek Road, Troy, MT 59935, USA; 4Centre for Animal Parasitology, Canadian Food Inspection Agency, Saskatoon Laboratory, 116 Veterinary Road, Saskatoon, SK, Canada S7N 2R3 ABSTRACT: Thirty-six moose (Alces alces) reported as acting abnormally were examined in north- western Ontario and adjacent northeastern Minnesota in 1986 – 2000. Thirty-four typically had little fear of humans, remained in an area for some time, and showed clinical signs of neuromotor inco- Parelaphostrongylus tenuis - P. tenuis typical neurological signs was found in 14 more, but examination was impossible or incomplete for 9 P. tenuis for P. tenuis the sample (21/34) and 10 were judged underweight. The remaining 2 moose in the sample, although P. tenuis. Moose with adult P. tenuis (U = 20, P - the P. tenuis P. tenuis exposure experienced by moose populations sharing range with infected white-tailed deer. Key words: Alces, meningeal worm, moose disease, moose sickness, parelaphostrongylosis, Parela- phostrongylus tenuis Parelaphostrongylosis is a disease in moose (Alces alces) and other ungulates caused by a neurotropic nematode, Parela- phostrongylus tenuis, spread by white-tailed deer (Odocoileus virginianus) which is the - ester 2001). In extreme cases, infected moose may show a pronounced posterior weakness - fected may lack fear of humans or show only slight, transitory signs such as unsteady gait experimental work (Lankester 2002), the 2Present address: 101-2001 Blue Jay Place, Courtney, BC, Canada V9N 3Z6 Road, Ottawa, ON, Canada K2H 8P9 DIAGNOSING PARELAPHOSTRONGYLOSIS IN MOOSE – LANKESTER ET AL. ALCES VOL. 43, 2007 parasite burden, the age of the infection, and possibly the host’s immunological familiar- ity with the parasite. In the wild, only the be reported. Yet, because of their large size, careful post-mortem examination of animals showing signs is a daunting task and may be typical suite of recognizable neuromotor signs accurately predicts P. tenuis infection in moose has not been examined thoroughly. - losis has been known for many years but important aspects of its pathogenesis and impact on moose populations remain unclear. An early experiment demonstrated that when to calf moose, P. tenuis can cause a rapidly - derson 1964). As well, naturally infected in the cranium, making it tempting to think that moose were particularly susceptible. The only where they were almost totally isolated study of contemporary moose populations the impact of parelaphostrongylosis on moose is likely more subtle and complex (Whitlaw and Lankester 1994a,b). Moose currently persist in many areas of eastern North America where deer densities (Whitlaw and Lankester 1994b). When deer 2, P. tenuis may cause only low, and marginally limiting mortality (Karns 1967, Lenarz and Kerr 1987, Whitlaw and Lankester 1994a, Dumont and P. tenuis marked moose population declines (Whitlaw and Lankester 1994a) and could again with numbers. The current and future impact of parelaphostrongylosis on moose populations may be underestimated because of our limited exposed animals. This paper describes the clinical manifes- period in northeastern Minnesota and north- procedures and tools used to determine which had parelaphostrongylosis. METHODS by the authors (Murray Lankester and Wm. of 14 years (1986 – 2000). A description of taken on occasion. When possible, the age of animals was estimated by tooth eruption and wear. On the basis of their size alone, 7 animals whose teeth could not be exam- ined were simply categorized as adults (i.e., conducted and the head, feces, and serum (in 4 instances) collected and frozen until exam- surface inspected using a stereomicroscope at 16X. Within the cranium, the inner surface of the dura was examined for worms and all searched for adult P. tenuis using the method and decanted, and the sediment examined for initially using the classical Baermann funnel technique and in later years (after 1994), the - rester and Lankester 1997). Numbers of ALCES VOL. 43, 2007 LANKESTER ET AL. - DIAGNOSING PARELAPHOSTRONGYLOSIS IN MOOSE No. Date examined Location1 Sex Age (years) Abnormal signs P. tenuis meningitis2 feces 13 9/22/1986 MN Yes ? ? 0 2 12/7/1986 MN Yes 0 ? ? 3 MN M 1 Yes 0 ? 0 4 9/24/1987 MN Yes ? 0 11/17/1988 MN 3+ Yes Yes 0 6 12/26/1988 M 0.6 Yes ? 2.8/g 7 1/10/1989 TB A Yes 0 Yes ? 8 2/7/1989 MN Yes 0 Yes 0 9 6/9/1989 TB M 1+ Yes Yes 2.2/g 10 2/3/1991 A Yes Yes 0.3/g 114 3/26/1991 M 2+ Yes ? ? 0 12 MN M 1 Yes ? 0 13 6/18/1991 MN M Yes 0 Yes 0 14 12/2/1991 TB A Yes 0 Yes 0 2/13/1992 8+ Yes 0 ? 0 16 2/17/1992 MN M A Yes 1M Yes 0 174 3/16/1992 MN ? A Yes ? ? 0 18 3/19/1992 MN M 0.8 Dead Yes 0 19 9/7/1992 MN Yes Yes 0 20 10/24/1992 MN Yes 0 No 0 21 12/3/1992 3+ Yes 0 No 0 22 12/9/1992 A Yes 0 ? 0 236 3/19/1993 MN 2 Atypical 0 No 0 243 1/1/1994 MN M 0.6 Yes ? ? 0 4/18/1994 KE 1+ Yes Yes 0.2/g 26 ??/06/94 SGPK A Yes 0 No ? 276 6/18/1994 MN 4 Atypical 0 No ? 28 7/4/1994 MN 14 Yes 0 (cord only) Yes 0 29 7/7/1994 1+ Yes Yes 0 (cranium+) Minnesota, 1986-2000. 1 2 3 4 Lens or cornea of 1 or both eyes opaque. 6 7 DIAGNOSING PARELAPHOSTRONGYLOSIS IN MOOSE – LANKESTER ET AL. ALCES VOL. 43, 2007 fresh fecal material. An enzyme-linked im- munosorbent assay (ELISA) was conducted on serum from 4 clinically abnormal moose and on 4 control moose from an area without P. tenuis. The method was similar to that and natural parelaphostrongylosis in moose (Ogunremi et al. 2002a) and white-tailed an anti-IgG conjugate produced according to Ogunremi et al. (2002a). Mean ages and mean number of adult worms found include Statistical analysis of mean ages was carried out with the Mann-Whitney (U) test. RESULTS Marais, Minnesota (n Ontario (n Ontario (n = 10) in 1986 – 2000 (Table l). animals (#23 and 27) were described as being otherwise showed normal gait and coordina- and 10 of the 36 were judged to be underweight or undersize for their age. The mean age of 29 animals for which tooth-age estimates reported in all months of the year including the remaining seasons. moose included 1 or more of the following: lack of fear upon human approach (13 moose), remaining in an area for an extended period (13, including the 1 found dead), walking or swimming in circles (8), inability to stand (incoordination) (7), partial paralysis mani- tilted to one side (4), head and neck turned posteriorly (torticollis) (6), standing with legs No. Date examined Location1 Sex Age (years) Abnormal signs P. tenuis meningitis2 feces 30 8/3/1994 MN 4 Yes Yes 0 313 8/20/1994 KE M 1+ Yes ? ? 0.12/g 32 10/19/1994 SGPK M Yes Yes 0 337 MN M 0.9 Yes Yes 0 (cranium+) 34 KE Yes 0 No 0 7 6/14/1999 TB 1 Yes Yes 0.7/g 36 1/6/2000 MN Yes 0 No 0 northeastern Minnesota, 1986-2000. 1 2 3 4 Lens or cornea of 1 or both eyes opaque. 6 7 ALCES VOL. 43, 2007 LANKESTER ET AL. - DIAGNOSING PARELAPHOSTRONGYLOSIS IN MOOSE positioned wide apart (wide base stance) or twitching (nystagmus) (3), unsteady gait (2), knuckling of lower limb joints or stumbling of these signs were not collected for further examination. Of 13 animals described as re- maining in the same area for extended periods, the initial sighting while one was reportedly present in the area for up to 10 months. Adult P. tenuis were found in the cranium parelaphostrongylosis. An additional animal its feces identical to those of P. tenuis. The mean age of 14 animals with adult P. tenuis (U = 20, P = 0.006). Worms in the cranium were most fre- quently located on the surface of the brain or 3 animals, portions of worms penetrated into brain tissue. Worms in 2 moose were located The mean number of adult P. tenuis found moose with adult worms in the cranium were - but none in feces. All moose with adult P. tenuis in the cranium (except 3 unsuitable for detailed - and across the surface of the pia-arachnoid The piarachnoid had a whitish cloudy appear- ance and loose patches of yellowish exudate were often seen on the brain surface. An cloudy meningitis but neither adult worms in one or both eyes (Table 1). All heads had been frozen and thawed before examination. Histologically, the eyes of #36 were considered Wildlife Health Centre, Saskatoon), despite the lens of one eye appearing enlarged and opaque. The eyes of the remaining 4 moose were not examined histologically. had neurogical signs typical of P. tenuis infec- tion except #23 that was killed because it was P. tenuis exposure. The highest titre (1,140 units occurred in a 10-month-old calf (#33) with 1 adult worm in the cranium, but a lower titre (140). Its serum sample was contaminated with ingesta (titre < 10 units). DISCUSSION Thirty-four of the animals examined here showed a reasonably consistent set of clinical signs not unlike those described by some of the earliest workers studying moose sick- ness (Thomas and Cahn 1932, Lamson 1941, stage of infection (Anderson 1964, Lankester 2002). Animals recently infected with only can appear lethargic, walk with occasional DIAGNOSING PARELAPHOSTRONGYLOSIS IN MOOSE – LANKESTER ET AL. ALCES VOL. 43, 2007 knuckling, stumbling, or an unsteady gait. unaffected. Other animals, presumably with manifestations of P. tenuis infection. Signs include marked paresis or weakness of the hind-quarters, wide-base stance needed to maintain balance, circling, head tilted or turned - ing, or being unable to stand. Total paralysis Nystagmus, or twitching of the eyes, often seen suggest a balance disorder. Animals showing - nial nematode infections, for example, moose in Sweden with Elaphostrongylus alces and caribou in Newfoundland with E. rangiferi - - cal of parelaphostrongylosis. Interestingly, an P. tenuis. On the basis of typical neuromotor signs, this diagnosis could be corroborated in only 22 P. tenuis P. tenuis no head examined), and no worms or cloudy remaining 12 moose with typical neuromotor infection on examination (3) or examination was incomplete (9). These results are compa- rable to those of Smith and Archibald (1967) and Gilbert (1974) who both found worms in It is impossible to determine whether their - able P. tenuis. - losis in moose of North America is possible when long slender nematodes can be located within the cranium. Male worms can be P. tenuis is expected in that location (E. rangiferi in moose of Newfoundland is an exception). But conducting a reliable cranial examination requires appropriate necropsy tools and facili- ties and some experience on the part of the muscle worm, P. andersoni, also becomes moose of the study area since it is not known in deer of northeastern Minnesota (Peterson and P. tenuis can now be distinguished from those of P. andersoni (and other related species) using molecular diagnostic methods (PCR-polymerase chain reaction and SSCP- single-strand conformation polymorphism) 2006). accumulation of lymphocytes, plasma cells and eosinophils is a known feature of P. tenuis infection (Anderson 1964, Smith et al. 1964, Smith and Archibald 1967, Lankester 1974) examination. Thus, brain tissue must be in in formalin or quickly frozen. Animals found dead in the warmer months, or heads left for periods in the sun before freezing, will be un- to yellowish) of the meninges, especially in the pia-arachnoid membrane against the brain ALCES VOL. 43, 2007 LANKESTER ET AL. - DIAGNOSING PARELAPHOSTRONGYLOSIS IN MOOSE the presence of loose, yellowish-red accumula- in the subdural space, on top of, or beneath the brain. Meningitis is most easily appreciated and thawing and any degree of post-mortem change decreases the likelihood of recognizing it. Meningitis resulting in cloudiness of the examined moose with P. tenuis in the cranium - mal moose in which no worms were located. Either worms were missed in the latter group of killing worms in the cranium and abnormal worms is gone (Lankester 2002, Ogunremi an eosinophilic meningoencephalitis along the diagnosis of parelaphostrongylosis in the P. tenuis (Ogunremi et al. 2002a). Used here, it correctly present in the cranium. Of equal interest was of P. tenuis could be found. Without the ELISA P. tenuis diagnosis could only of typical clinical signs. Although atypical, of this study, infections in more clinically The P. tenuis SK (contact: gail.krohn@pds.usask.ca). - proximately 1 ml) is required for the ELISA. Although serum ideally is separated from be directed at the chest to cause bleeding into examination). Vehicle-killed animals may between the ribs on the “down side” of the animal will release the pooled blood that can be drained into a container (plastic bag or jam sawn open or accessed through the diaphragm be scooped into a container, although samples badly contaminated with rumen material are room temperature for a few hours allowing a clot to form and then chilled in a refrigerator pipetting the straw-coloured serum into small by red blood cells, the serum will be red and “bloody” and the contaminating red blood serum or allowed to settle and the watery, occur during sample collection and prepara- tion in which case the serum sample will be red or reddish. As long as such samples were promptly frozen after preparation, testing can still be successfully carried out. Whole blood put directly into the freezer may not be used in the ELISA. Results reported here contribute to our understanding of P. tenuis infection rates in feces was used by Lenarz and Kerr (1987) to moose were infected with P. tenuis. Their in Minnesota by Karns (1977) who found DIAGNOSING PARELAPHOSTRONGYLOSIS IN MOOSE – LANKESTER ET AL. ALCES VOL. 43, 2007 Kerr (1987) arbitrarily chose a more conser- infected moose. In our study, determining the all moose exhibiting typical neuromuscular is not appreciably different from that chosen moose with less conspicuous, or sub-clinical signs, were also included, the larger sample denominator would further lower the expected and thereby increase the predicted rates of P. tenuis infection in the population. In addi- tion, it is important to recognize that these are “point in time” estimates that ignore the may be short but ongoing. This could further increase estimates of annual morbidity and mortality. samples because of the habit of sick animals staying for long periods in one area. Thirteen of 36 abnormal moose examined here were 1 – 2 weeks. This can bias fecal collections. studies in the same areas (Upshall et al. 1987, McCollough and Pollard 1993). Animals with parelaphostrongylosis often spend consider- able time in a limited area depositing pellets whether shedding occurs more in one season Other parasitic diseases are known to be important to moose health but the pattern of their epizootics differs from that expected of meningeal worm. Ticks (Dermacentor albi- pictus) kill moose, usually in late winter and hair loss and numerous carcasses being found following a “ticky“ winter (Samuel 2004, dependent on moose densities and on weather only 1or 2 winters and are not dependent on densities of co-habiting deer. In contrast, historical moose declines in which P. tenuis was thought to play a role, were characterized peaked (Whitlaw and Lankester 1994a). The Fascioloides magna) is a parasite whose impact on moose is not fully understood but has recently been implicated in a moose decline in northwestern Minnesota (Murray et al. 2006). In contrast - tion in moose will be related to densities of in moose, but instead requires deer or wapiti (and the presence of appropriate aquatic snail, Lymnaea spp.) for dissemination. They are go unnoticed if present and do not occur in Although some progress has been made in recognizing meningeal worm infections in - and other diseases such as winter ticks in limiting moose numbers, continues to be a challenge. Results reported here demonstrate that the display of a typical set of neuromotor clinical signs is a reasonably good indication ALCES VOL. 43, 2007 LANKESTER ET AL. - DIAGNOSING PARELAPHOSTRONGYLOSIS IN MOOSE - nosis, and the possible detection of sub-clinical animals, can be expected using the P. tenuis ELISA. 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