Ticha Padgett-Stewart - May 2018

Hi! I am Ticha Padgett-Stewart and I am a Junior studying Microbiology at MSU. This summer I am working on a disease ecology project under the guidance of Dr. Raina Plowright in the Microbiology and Immunology department. Disease ecology is the study of how environmental and behavioral factors can impact the transmission of disease through a single given species, or even through multiple species. The pathogen I will be focusing on for this project is Hendra virus. Hendra virus is an emerging disease in Australia, meaning a disease that has newly appeared in a population or area where it hasn’t been observed before. Studying emerging diseases is particularly important, because they often lack developed treatments and therefore have higher probability of causing a major epidemic, or even pandemic.

While Hendra virus is a new disease to humans, it naturally exists in the flying fox fruit bats of Australia, making them the ‘reservoir host’ for the disease. Hendra virus only becomes a problem when bats transmit the virus to horses, who can then give the virus in turn to people, where it can be deadly. These transmission events are rare, and only happen when a million little circumstances all happen at the same time. This alignment of circumstances that allows for this to occur can be visualized as slices of swiss cheese laying on top of each other, with some layers having bigger holes than others, representing a higher chance of transmission. What's more, these holes must be aligned in both space and time in order for a transmission event to go all the way from bat to human.

Above, is a figure from the paper “Pathways to Zoonotic Spillover” (Plowright et al., 2017) representing this mental map of disease transmission, which additionally outlines what each layer represents. More specifically, my project will be working mostly on the ‘animal ecology’ layer of transmission. My question is, will the number of parasites a bat has impact its likelihood to have Hendra virus? To test this, I will be capturing flying foxes and testing them for the presence of Hendra virus and also collecting data on the bat’s parasite load. I will also be sampling feces from areas underneath where bats roost and testing for parasite presence in those, to get an idea of a more population wide parasite load.

I leave for Australia on May 16th and will be working with a team of disease ecologists based out of both MSU and Griffith University in Brisbane who have already done a ton of work on the ecological dynamics of Hendra virus. I will be very lucky to have their knowledge and technical expertise to rely on! So far, my work has been mostly reading a lot of journal articles and working on preparing protocols for my sampling, but I will have my first bat capturing day on the 25th. I am extremely fortunate to be working with the Institute on Ecosystems for this project and I am looking forward to a summer of science!


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