P. Kafle, Kutz Lab, Department of Ecosystem and Public Health, University of Calgary

Morphological diagnosis of protostrongylids (dorsal - spined) infecting

muskoxen and caribou in the Canadian Arctic

Dr. Pratap Kafle

This is the protocol for the differentiation of the first stage larvae of three protostrongylid

nematodes that infect muskoxen and caribou in the Canadian Arctic with the help of a

compound microscope. The diagnostic features were identified and validated by Pratap Kafle

and published in the two papers: Kafle et al., 2015 and 2017.

The first guide contains the diagnostic keys for two protostrongylids that infect muskoxen:

1. Umingmakstrongylus pallikuukensis

2. Varestrongylus eleguneniensis

These parasites are important pathogens of muskoxen, as reflected by their increasing

prevalence and intensity of infection and expanding geographic range over the past decades.

Previously confined to the North American mainland, these two parasites were discovered in

muskoxen on Victoria Island in the Canadian Arctic Archipelago for the first time between 2008

and 2010. Currently, they are undergoing range expansion to the higher latitudes across

Victoria Island and increasing in prevalence and intensity of infection.

The second guide contains the diagnostic keys to differentiate the two most common

protostrongylids that infect caribou in the Arctic and sub-arctic regions of Canada

1. Varestrongylus eleguneniensis

2. Parelaphostrongylus andersoni

Among the known caribou protostrongylid fauna, V. eleguneniensis and P. andersoni appear to

be the two most common and widespread species. Parelaphostrongylus andersoni, a muscle

worm, was first reported in white-tailed deer but also infects caribou and moose, covering an

extensive geographical area in northern North America. Varestrongylus eleguneniensis, a

recently described lungworm, is found in caribou and muskoxen, and occasionally moose, and

has a wide geographic distribution from arctic to boreal regions of North America. These two

species of protostrongylids co-occur in caribou throughout much of this host's range and can

cause a varying degree of pathogenicity.

P. Kafle, Kutz Lab, Department of Ecosystem and Public Health, University of Calgary

As these parasites are undergoing changes in their distribution and infection intensities along

with rapid Arctic warming, reliable and efficient methods that can diagnose and differentiate

these lungworms are needed to track range changes and inform management decisions

effectively. This protocol presents the validated laboratory guide that can be used to

differentiate these three species of protostrongylids using microscopy.

Methodology:

1. First stage larvae (L1) are isolated from feces using the beaker Baermann technique.

2. Larvae are placed on a clean glass slide in a drop of water and heat killed by passing the

slide 10 times over the Bunsen burner flame.

3. Once heat fixed the slides are examined microscopically in detail under bright-field and

differential interference contrast (DIC) microscope at 40 x objective magnification.

4. Focus on the tail region of the larvae and look for the diagnostic keys described in the guide

below.

5. Perform morphometric measurements (mainly total length, width, tail spike length) if the

morphological identification is not conclusive

P. Kafle, Kutz Lab, Department of Ecosystem and Public Health, University of Calgary

Guide 1

P. Kafle, Kutz Lab, Department of Ecosystem and Public Health, University of Calgary

Guide 2

P. Kafle, Kutz Lab, Department of Ecosystem and Public Health, University of Calgary

Images of first stage larvae

1. Umingmakstrongylus pallikuukensis

P. Kafle, Kutz Lab, Department of Ecosystem and Public Health, University of Calgary

2. Varestrongylus eleguneniensis

P. Kafle, Kutz Lab, Department of Ecosystem and Public Health, University of Calgary

3. Parelaphostrongylus andersoni

Contact information:

Pratap Kafle pkafle@ucalgary.ca

+1 403 926 0529