Zebra-eating plants spread anthrax

Carnivorous plants have always fascinated me. So when I saw this link on Facebook a few years ago, I was quite excited! The link (and this video) claim that the bromeliad Puya chilensis eats sheep. That’s right. A plant that eats sheep! The sheep are ensnared in the plant’s thorns until they succumb to exhaustion and die, and then their rotting carcasses feed the plant. We don’t actually know that the plants have evolved to “catch” and eat mammals, of course. An alternative explanation is that sheep are just rather unintelligent. But the idea is fascinating.

Whether some plants intentionally kill mammals or not is up for debate, but plants do eat mammals. Kind of. For instance, in Namibia, zebra carcasses increase soil nutrient concentrations for at least a year after the animal dies (Turner et al. 2014), and during that initial year, grass biomass near carcasses is higher than randomly-selected carcass-free sites (Turner et al. 2014).

The higher grass biomass near carcasses causes zebra and other ungulates to be attracted to carcass sites to forage (Turner et al. 2014). You might be thinking that foraging near a dead zebra body might be a bad idea for a zebra, and you’d be right. Namibia is one location where anthrax (caused by the bacterial pathogen Bacillus anthracis) naturally infects wildlife, so contacting a carcass could mean contacting anthrax spores. And zebras should worry about more than just the carcasses; the soil, grass roots, and grass at carcass sites all harbor anthrax spores, at least for the first year after the carcass appears (Turner et al. 2014).

If visiting carcass sites exposes zebras to a potentially lethal pathogen, why don’t zebras avoid carcasses? Well, they do, but only a little bit. When a carcass is relatively fresh, zebras are less likely to visit carcass sites than control sites, but that avoidance doesn’t last until all of the anthrax has left the grass. Therefore, sexy, delicious grass may facilitate anthrax infections in zebra.


Turner WC et al. 2014 Fatal attraction: vegetation responses to nutrient inputs attract herbivores to infectious anthrax carcass sites. Proc. R. Soc. B 281: 20141785. http://dx.doi.org/10.1098/rspb.2014.1785

Parasites in the News – January 2017

If you haven’t voted on the best 2016 Parasite Ecology cartoon yet, please do! If you did, thanks! Have some links!

Not Up for Debate: The Science Behind Vaccination (New York Times)

We are resurfacing this article in light of the news that Robert Kennedy Jr., an anti-vaccine crusader, has said he has been asked by President-elect Trump to lead an immunization safety committee.

Relatedly, it looks like the measles vaccine protects children from more than measles.

A research crew went on a quest for the ‘Lost City of the Monkey God.’ They nearly lost their faces for it.”

And finally, the prawns-eat-snails-to-reduce-Schistosoma-transmission project in Senegal was covered by BBC news, reminding me of that one time I tried to draw a motorcycle.


Yikes. That prawn terminator, though.

Have a good weekend!

Best parasite ecology cartoon of 2016?

It’s the first week of the new year, which means that you get to vote on the best parasite ecology cartoon from last year! In 2013, the winner was “Social Networking in Lemurs,” a cartoon about this study that painted lice on lemurs to infer lemur contacts. In 2014, the winner was “Oldest Trick in the Book,” a romantic cartoon about a snail who was castrated by trematodes. And in 2015, the winner was “Bring out yer dead (prairie dogs),” a Monty Python reference tied to a cool prairie dog plague paper. So which 2016 cartoon was best? I’m opening up the voting for these candidates:

(1) The case of the not-so-boring isopods


(2) A sworm of soldier trematodes


(3) Slugs. Ruin. Everything.


(4) The Curse of the Magical Seed Dispenser


(5) Frogald Stump bans immigration and destroys frog metapopulation stability


(6) “Parasite” fashion show


(7) House cats out of the dog house after Toxoplasma accusations 


(8) Overly-frequent arousal can kill you


(9) Weird vibrations


(10) Survival of the fattest


(11) May the force of infection be with you


Let the voting begin! You can pick your top three favorites using this poll:






2016 Parasite Ecology #260papers

Happy New Year!

I started blogging roughly four years ago with several goals in mind, one of which was to spend more time reading the literature. There is no question that blogging caused me to read more. But last January, Meg Duffy posted about her progress on her goal to read 260 papers in 2015,* and that made me wonder: how many papers do I actually read in a year?

I’m a big fan of tracking my personal productivity by keeping a time journal, so Meg’s idea for keeping an academic reading journal was instantly appealing. And thus I wrote down every paper that I read in 2016. I learned a lot about my work habits by doing this, so I decided to write a post about the experience, in case some of you are also interested in giving it a go in 2017.

Like Meg, I only recorded the papers that I read thoroughly (i.e., to the level that I would read a paper for a lab meeting). I must have skimmed at least three times as many papers as I actually read, especially during periods where I was reading to prepare to write grant proposals and manuscripts. To get an idea of how consistently I read thoroughly, I made this plot of my paper-reading timeline for 2016. I made an Excel spreadsheet that automatically updated this plot every time I added a paper, which helped me to track my progress.


My goal was to stay above the orange line all year, and I pretty much succeeded! As I write this post on 28 December, I have read 245 papers, leaving me 5 papers/day if I really want to reach my #260paper goal by December 31st. That’s not too bad! I would have surpassed my goal if it wasn’t for fall field season. Unsurprisingly, I gave up reading (and regular showers and normal eating habits) for a few weeks of intense data collection, as I do every year. I wish I had kept up with reading during that time, but oh well.

You might be wondering which journals are most frequented by a self-proclaimed parasite ecologist. Of the 245 papers that I read, there were only 12 journals that showed up five or more times: Conservation Biology, Ecological Applications, Ecology, Ecology Letters, Journal of Animal Ecology, Journal of Parasitology, Philosophical Transactions of the Royal Society B, PNAS, Proceedings of the Royal Society B, Science, TREE, and Trends in Parasitology. There weren’t any huge surprises there, except maybe Philosophical Transactions of the Royal Society B, which had some excellent and recent special issues that I dug into.

Also unsurprisingly, most papers were recent, with ~16% of papers published in 2016. I did read some older papers, but I want to do a better job of digging into the older literature in 2017 – partially because I think it’s important, and partially because it’s fun! (The bin sizes on this figure are purposefully uneven.)


I also kept track of why I read each paper, though I don’t think most of those data would be interesting to people besides me. I was somewhat surprised to find that only 19 (8%) of the papers that I read in 2016 were specifically for blogging purposes. It seemed like blogging increased my reading by so much more! But an additional 20 papers were stuck under the heading of “other reading,” and many of those could have ended up on the blog, but for whatever reason I decided not to write about them. Finally, I was not surprised to find that the most common reason for reading a paper was preparing for grant writing. Because it was a busy grant year, grant preparation accounted for a whopping 42% of the papers that I read.

So there you have it! I’d be interested to hear your suggestions on how best to spend my reading time in 2017. Anyone have some neat “old” parasite ecology papers to suggest?

*#365papers was co-founded by Jacquelyn Gill.

North Pole Parasites: Curious Cases of Carnivorous CWalruses

Walruses have awesome faces. (Photo credit: Wikipedia)


If you’ve ever wondered why walruses have mustaches, the answer is that walruses use their sensitive vibrissae whiskers to find delicious benthic organisms to snack on. But do walruses only eat stuff living on the sea floor? Why no, no they don’t. Sometimes, walruses eat seals.

Near Halloween, I read a rather spooky paper from 1960 that claimed that walruses can either be facultative or obligate seal eaters (the paper called the obligate seal-eaters “carnivores”). I haven’t seen any recent literature contradicting Fay (1960), so here is an apparently accurate bit of spooky information for you:

“The obligate carnivore has never to my knowledge been observed by a biologist; the description of this type is based entirely on verbal reports from Eskimos. The obligate carnivores or “rogues” are said to be solitary bulls that feed principally or exclusively on vertebrates. In contrast to the facultative type, which is distinguishable from non-carnivores only by the stomach contents, the obligate carnivore has often a characteristic external appearance. It is relatively lean and slender, with shoulders and forelimbs appearing unusually large and powerfully developed; the chin, neck, and breast are impregnated with oil from frequent contact with seal blubber, and the oxidized oil imparts an amber colour to these regions and to the tusks (cf. Brooks 1954, p. 57). The tusks are exceptionally long, slender, and sharp-pointed, and their labial surfaces are covered with scratches. The exceptional length of the tusks might be due to a lack of the attrition which normally shortens the tusks of benthic feeders (Fay 1955, Mansfield 1958).”

So, there are “rogue” walruses with extra long tusks running around the Arctic, practically bathing in the blubber of the seals they kill. That’s bananas! But even when we ignore the rogues, normal walruses also eat seals sometimes, especially when other prey are hard to come by. And a decade ago, Rausch et al. (2007) predicted that increased sea ice loss would drive increased seal consumption by normal walruses.

You might be wondering why epic walrus-seal battles are interesting from a parasite ecology perspective. I’ll tell you! In the Arctic, there exists a parasitic worm called Trichinella nativa that infects many mammal species, including humans. I’ll talk more about Trichinella next time, but for now, let’s focus on transmission to humans. Humans in Arctic regions sometimes eat walruses, and because cooking walrus meat is not the norm, outbreaks of Trichinella nativa sometimes occur in Arctic populations. This has not been a huge risk, historically, because walrus populations generally have low prevalences of Trichinella infection. But apparently people avoid eating rogue walruses because their high seal diets make them more likely to be wormy. Similarly, Rausch et al. (2007) warned that in a warming world, Trichinella spillover from marine mammals to humans might become more common due to increased seal consumption by facultative seal-eaters.

The moral to today’s story is: you are (infected by) what you eat. And if climate change changes what you eat, climate change can also change what you’re infected by.




Fay, F.H. 1960. Carnivorous Walrus and Some Arctic Zoonoses. Arctic, 13(2): 111-122.

Rausch, R., J.C. George, and H.K. Brower. 2007. Effect of Climatic Warming on the Pacific Walrus, and Potential Modification of Its Helminth Fauna. Journal of Parasitology, 93(5): 1247-1251.