Ticks: a global issue

Veterinary Parasitologist, Shona Chandra, is finishing up her PhD at the University of Sydney. While you may not be familiar with Shona’s field, you are likely familiar with her chosen subjects: ticks. We caught up with Shona to learn more about her research, what she’s learned and why she’s sharing it with the scientific community.

Shona Chandra, Veterinary Parasitologist

What led you down this path of study? I was born in Malaysia – the brown dog tick is very common there. It thrives indoors and replicates so fast. My family loves dogs and if our dog ever picked one up, we’d find him completely covered after a few days. That started the fascination for me. As I grew up I learned more about all of the problems these small arachnids can cause.

What kind of damage do ticks cause in Australia? When I moved to Australia I learned about the paralysis tick which can paralyze animals and people. They’re so tiny but have so much power to cause harm. Most people have heard of Lyme disease, too, but there’s debate around if we actually have it in Australia or not. The bacteria that causes Lyme disease hasn’t been found here but people have reported “Lyme-like” symptoms.

Your latest paper is on nymph ticks, why did you focus on them? I wanted to know if there was any pathogenic material in Australia’s ticks that could potentially cause disease. ‘Nymph’ refers to their life stage. Ticks start as larvae, develop into poppy seed sized nymphs and moult one final time into adults. When ticks first hatch they tend to be free of disease. When they feed on a host they pick up lots of bacteria. By the time they moult into a nymph they are just full of material that can cause disease. I wanted to look at this stage because it’s generally when ticks have the highest potential to cause harm. It’s difficult to study ticks then though because you have to collect them before they have a chance to feed on a host.

This is what the “average” day looked like for Shona as she collected nymph ticks. Top left: Shona checking for ticks. Top right: A nymph tick (circled, black) compared to an Australian five-cent coin. Bottom: The view from one of the collection sites in Sydney, Australia. 

Collecting ticks, what did that process look like? I looked like a crazy person dragging a white towel around. I got a few disapproving looks from locals so I just explained my research to them. I used a white towel, the texture was enough for the ticks to grab on to. I did feel a bit strange, stopping every ten paces to check the towel. I gathered about 150 nymphs which took five months. The beach views made it worth it, though.

After collecting nymph ticks, Shona sequenced their DNA to determine species. Then she sent DNA samples to another lab to get a full report on each ticks’ microbiome.

What did you find? We found two bacterias that we weren’t expecting. One had only been reported in one Australian paper before and even in that paper they didn’t find the bacteria in a high number of ticks. We found that most of our nymph ticks carried a lot of it. We realized that this bacteria is potentially acquired by nymph or larvae ticks but then migrates to the host. The ticks we studied generally feed on humans and dogs and this bacteria is closely related to one that causes disease in humans. We were surprised to find this potentially pathogenic material.

All of Shona’s data (even her collection site coordinates) are publicly available via LabArchives.

Why did you choose to make your data publicly available? The damage ticks can cause is a global issue. I think in science it’s really helpful to share your data. I notice that some scientists  tend to not make their data available but I think that is quite restrictive. Other people could find something similar but they won’t know if you don’t share your data. We’re in a world where it’s so easy to share and compare data and really it benefits the community. 

View Shona’s research within LabArchives, here.