climate change and the muskox nematode biology 3700 emilie ontko march 23 rd 2011

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