climate change and the muskox nematode biology 3700 emilie ontko march 23 rd 2011
TRANSCRIPT
Climate Change and the Muskox Nematode
Biology 3700 Emilie Ontko
March 23rd 2011
Nematode
• Umingmakstrongylus pallikuukensis
• Large protostrongylid lungworm
• Dioeceous• Forms large cysts
deep in the lungs• Discovered in
Nunavut in 1988
Novel Parasite or New Discovery
• No historical baseline for parasites• Not a recent host switch• Reasons for non-detection before 1988:
– Low infection levels– Minimal contact between people and Muskox– Hunters discard lungs– Cysts mistaken for hydatid cysts– Highly restricted range
• Only detected by luck after follow-up of death of a radio-collared individual
Life Cycle
Life Cycle Facts
• Pre-patency period ~91-95 days• Patent period > 22 months • L3 larvae ingested during summer• Takes two years to mature from L1-L3 in
gastropod host• Migration route from GI tract to lungs not known• Cysts: tough, grey and well defined
– Contain at least 1 male, 1 gravid female, free eggs and L1 larvae
Experimental Results
• 1999: Prevalence up to 92% of L1 in fecal samples
– Up to 258 cysts in one animal
• 2004: Prevalence of infection 100%
– Intensity >100 cysts/animal
Hypotheses on Pathology
• No clinical sign of pathology
• In established infections pathology is limited to the cysts
• Inflammatory response and small lesions found in developing infection
• Exercise intolerance
Hypotheses on Pathology
• Caused by displacement and compression of alveoli and lung spaces
• Infected animals move slower and have been reported to bleed from the nostrils
• Predators prey on slow moving animals
• Exercise intolerance may be significant
Other Definitive Hosts
• Investigations of parasite with:– Domestic Sheep– Dall’s sheep– Sympatric moose– Sympatric caribou
• Restricted to Muskox• Post mortem Dall’s sheep: no encysted or
living parasites, but legions on liver and lungs
Climate Change
• Significant and unprecedented warming in West-Central Canadian Arctic and Subarctic– Increase of an
average of 2.0 degrees
• Earlier springs and later autumns
Effect on Muskox
• Warmer summers larvae can develop from L1-L3 within the summer
• Longer summer increase chance that larvae can develop to L3 in one summer
• 50% decline in population in infected areas, other areas increased significantly (Studied 1988-1994)
Future Worries
• Spread to areas with suitable gastropod host
• Prevalence of infection in all infected populations will increase
• Possible host switch to more domesticated and utilized host
• Switch of other ungulate parasites to Muskoxen
References• Kutz, S.J., Hoberg, E.P., and Polley, L. Experimental infections of muskoxen
(Ovibos moschatus) and domestic sheep with Umingmakstrongylus pallikuukensis (Nematoda:Protostrongylidae): parasite development, population structure, and pathology. Canadian Journal of Zoology; Oct 1999. 77(10): 1562-1572
• Kutz, S.J., Hoberg, E.P., Nagy, J., Polly, L. and Elkin, E. “Emerging Parasitic Infections in Arctic Ungulates. Integrative and Comparative Biology, Apr. 2004. 44(2): 109-118
• Kutz, S., Garde, E., Veitch, A., Nagy, J., Ghandi, F., and Polly, L. Muskox Lungworm (Umingmakstrongylus pallikuukensis) does not establish in experimentally exposed thinhorn sheep (Ovis dalli). Journal of Wildlife Diseases, 2004. 40(2): 197-204
• http://mottafied.com/?p=48• http://www.cdc.gov/eid/content/14/1/10-g1.htm• http://www.rvc.ac.uk/review/parasitology/LungwormSheepGoat/
Dictyocaulus.htm• http://www.enr.gov.nt.ca/_live/pages/wpPages/muskox_lungworm.aspx• http://www.elcivics.com/mount_mckinley_alaska_3.html