Graduate Student Profile
BS in Zoology with an emphasis in fisheries, wildlife, ecology, and behavior from North Dakota State University
My PhD work has focused on the ecology of Cryptosporidium parasites in wild small mammal populations. Cryptosporidium is a genus of ubiquitous parasites that can cause the disease cryptosporidiosis. There are at least 26 species and more than 70 different genotypes of Cryptosporidium (aka crypto) that have been found in more than 450 vertebrate host species, of which, more than half are mammals. Many of these parasites are considered to be host-adapted, which means we tend to find specific types of Cryptosporidium in a particular host species or group of hosts. This knowledge has been used to track sources of water contamination and characterize human health risk. Cryptosporidium research has largely focused on the Cryptosporidium species and genotypes affecting humans and livestock, because of human and animal health as well as the economic importance. However, relatively little is known about Cryptosporidium in wildlife host species besides “X” Cryptosporidium was detected in “this” host species, and if the Cryptosporidium species or genotype detected in non-human hosts has been found in humans.
I focused my research on some of the lesser studied Cryptosporidium parasites found in wildlife host species. Although “focused” may not be the right word since I found more than 18 types of Cryptosporidium - mainly genotypes of which we know very little about, in over 14 host species (voles, muskrats, Peromyscus mice, tree and ground squirrels). My background in ecology and zoology has given me a unique perspective to studying Cryptosporidium-host interactions, as I aim to look at both the host and parasite perspectives. I believe by gaining a better understanding of the ecology of Cryptosporidium parasites in wild host populations, we can learn a lot about basic Cryptosporidium biology and evolution. To understand an obligate, internal parasite such as Cryptosporidium, we also need to take into account the host ecology, biology, and evolution. We can better assess the public health impact of the changing boundaries between humans and wildlife by studying how and why host-parasite dynamics vary between communities.
A few important outcomes of my research include: 1) There are highly divergent copies of the 18S rRNA gene (only ~93% similarity) of Cryptosporidium chipmunk genotype II in eastern chipmunk (Tamias striatus) hosts. This degree of divergence between 18S rRNA gene copies is more similar to what is found in some Plasmodium species, where the types are expressed at different life stages of the parasite. 2) Although the 18S rRNA gene is the most popular target for identifying and sequencing Cryptosporidium, there can be a large degree of heterogeneity in 18S rDNA sequences within a Cryptosporidium genotype. The identification and phylogenetic relationships of Cryptosporidium genotypes can be clarified with the addition of other loci such as the actin and HSP70 genes.
I now have even more questions than answers that I would like to follow-up on. I would like to continue to work on the ecology of Cryptosporidium parasites in wildlife, but also branch out to other parasites and wildlife diseases. One area I am particularly interested in is parasites (Cryptosporidium or other parasites) in hibernating animals. How do Cryptosporidium parasites survive when the host animal is in hibernation and undergoes significant physiological changes? I am also interested in the ‘phylobiogeography’ of hosts to better understand host-parasite relationships, specifically of Cryptosporidium in voles of the genera Myodes and Microtus. On another note, but still in keeping with multiple species interactions, I am interested in animal predation on crops (vineyards, orchards, or row crops) and how vineyards and orchards can be used to help conserve animal and plant biodiversity.
Environmental & Conservation Sciences Ambassador, ECS Graduate Student Association, VMS Graduate Student Association, Wildlife Society, Society for Conservation Biology, Wildlife Disease Association, American Society for Parasitology
Selected Publications/Notable Achievements:
Martin Kváč, John McEvoy, Brianna Stenger, Mark Clark. 2014. Chapter 5: Cryptosporidiosis in other vertebrates. Pg. 237-323. Cryptosporidium: parasite and disease. Editors: Simone M Cacciò and Giovanni Widmer. Publisher: Springer.
Peer Reviewed Publications
1. Kváč M, McEvoy J, Loudová M, Stenger B, Sak B, Květoňová D, Ditrich O, Rašková V, Moriarty E, Rost M, Macholán M, Piálek J. 2013. Coevolution of Cryptosporidium tyzzeri and the house mouse (Mus musculus). International Journal for Parasitology 43: 805-817.
2. Rasková V, Kvetonová D, McEvoy J, Edwinson A, Stenger B,Kvác M. Human cryptosporidiosis caused by Cryptosporidium tyzzeri and C. parvum isolates presumably transmitted from wild mice. 2013. Journal of Clinical Microbiology 51: 360-362.
3. Kváč MKestřánová M, Pinková M, Květoňová D, Kalinová J, Wagnerová P, Kotková M, Vítovec J, Ditrich O, McEvoy J, Stenger B, Sak B. 2013. Cryptosporidium scrofarum n. sp. (Apicomplexa: Cryptosporidiidae) in domestic pigs (Sus scrofa). Veterinary Parasitology 191: 218-227.
4. Feltus, D.C; Giddings, C.W.; Schneck, B.L.; Monson, T; Warshauer, D; McEvoy, J.M.; 2006. Evidence supporting zoonotic transmission of Cryptosporidium in Wisconsin. Journal of Clinical Microbiology 44: 4303-4308.
Stenger, B.L.S., Clark, M.E., McEvoy, J.M. Technical Report: Source Tracking of Cryptosporidium in the Red River Valley. North Dakota Water Resources Research Institute, Technical Report No: ND12-07, June, 2012.