Around the world in a thousand fleas


The International Congress for Tropical Medicine and Malaria (ICTMM) kicks off in Brisbane, QLD, Australia this week running from 18 through 22 September. This is a big conference and wonderful for local researchers to be showcased to an audience of international scientists from our own backyard in QLD.

I couldn’t make this meeting unfortunately but luckily my wonderful PhD student Andrea Lawrence will be presenting some of our flea research as part of the Australian Society of Parasitology conference that is incorporated into ICTMM this time around.

Andrea has been doing some excellent research during her candidature and you can read some of it here [Evaluation of the bacterial microbiome of two flea species using different DNA isolation techniques provides insights into flea host ecology] and here [Integrated morphological and molecular identification of cat fleas (Ctenocephalides felis) and dog fleas (Ctenocephalides canis) vectoring Rickettsia felis in central Europe].

This week she will be sharing her research into the genetics of global cat flea populations. You can catch Andrea on Tuesday 20 September in the Zoonoses session in M4, 13:00-15:00.

Our abstract is below:

One thousand fleas from fifty countries: global genetic structure and morphometrics of the common cat flea (genus Ctenocephalides) reveals phylogeographic patterns and resolves the generic complex.

Andrea Lawrence, Cameron E. Webb and Jan Šlapeta

School of Life and Environmental Sciences (SoLES), Faculty of Veterinary Science, The University of Sydney, Australia and Department of Medical Entomology, The University of Sydney and Pathology West, ICPMR, Westmead, Australia

The common cat flea and its relatives (genus Ctenocephalides) are considered the most successful ectoparasites on earth. The widespread parasitisation of these insects on mammals closely associated with humans (e.g. dogs and cats) represents significant potential for vector borne disease transmission. Fleas of the genus Ctenocephalides represent a unique model to study the effects of modern human migration and geographic and climatic barriers on parasite diversity and diversification. We have amassed a world-wide collection of Ctenocephalides over a period of 7 years, and analysed over 1000 flea samples from ca. 50 countries representing all continents bar Antarctica. Novel integration of morphology, morphometrics and molecular identification and phylogenetics using a combination of four mitochondrial and nuclear DNA markers, reveals phylogeographic patterns and evolutionary relationships of global cat flea populations. These techniques provide resolution of the long disputed Ctenocephalides generic complex, which has not yet been definitively resolved despite its significance in veterinary and public health. Understanding of contemporary population structure inferred from global phylogeographic analysis has implications for parasite and flea-borne disease management. It is hoped that this work will form the authoritative estimation of the origin of the genus Ctenocephalides and the subsequent species evolution and migratory radiation.

Keep an eye on the official conference hashtag [#ICTMM2016] and why not follow Andrea on Twitter for more!

The lead image on this article is modified from Andrea’s paper, “High phylogenetic diversity of the cat flea (Ctenocephalides felis) at two mitochondrial DNA markers






Summer summary of mosquito media madness


Summer is always a busy time for me. As well as plenty of time sloshing about in the wetlands, there is often lots of interest from mosquito-curious media. There has been some intense bursts of activity in previous summers but the 2015-2016 was particularly interesting.

I certainly covered some new ground this summer. I responded to over 160 individual media requests in the past 6 months. From flies and food safety to the emergence of Zika virus. Here is a wrap from my media adventures and some valuable lessons learned for future science and public health communication.


The good news of new virus discoveries

Usually, the discovery of a new mosquito-borne virus brings with it new concern for public health. This time though, there was some good news.

Towards the end of 2015, a paper reporting on a collaborative research project between University of Queensland, QLD Health and University of Sydney was published in Virology. This was the first publication detailing the discovery of Parramatta River virus, an insect specific virus that exclusively infects the mosquito Aedes vigilax. This virus does not infect people and poses no health risk.

A joint media release was issued by University of Queensland and University of Sydney and there was plenty of media attention. Not surprising given the usual negative associations with mosquito-borne pathogens!

There were dozens of articles, much of the attention focused on the team at University of QLD. Dr Jody Hobson-Peters was kept busy with local media including ABC and Brisbane Times. It was a great experience sharing the research with colleagues in Queensland, particularly great seeing so much exposure for PhD student Breeanna McLean and her newly published research.

I was surprised at how little attention there was in the news from Sydney media. The lesson here though was more about bad timing than uninteresting research. A couple of weeks after the initial media release, I forwarded around a few emails and sent out a couple of tweets and next thing you know, we made the front page of the local newspaper, the Parramatta Advertiser (see above). It was some great local coverage, not only about the virus discovery but it also provided an opportunity to raise awareness of mosquitoes and mosquito-borne disease on the eve of summer!

Lesson learned: A good reminder that if your research isn’t picked up immediately, give it another shot a few weeks later. Timing may make all the difference but perseverance does too!


To stop sickness, swat or spray

Just in time for Christmas lunch and summer holiday picnics, I published an article on flies and food safety at The Conversation. I really expected this article to slip under the radar of most people. Coming out on Christmas eve doesn’t seem likely many would be clicking about on the internet but within a few days over 600,000 people had clicked on the piece!

Many of those clicks were thanks to the article being shared by IFLS but there was also plenty of interest from local media and I was busy with interview requests from ABC Local Radio across the country. Who doesn’t love hearing about how flies poop and vomit on your food? I was even interviewed by Grey Nomad Magazine!

Lesson learned: Applying a little science to seasonal urban myths and common uncertainties can prove popular and may be a good opportunity to promote a little science!


Rain, rain everywhere with mozzies soon to come

With all the talk of El Nino and predictions of a hot and dry summer for the east coast of Australia, the summer was actually reasonably mild and extremely wet. Sydney was particularly battered by a series of storms and intense rainfall early in 2016.

More water generally means more mosquitoes. In response to the rain, many media outlets were interested in chatting about the prospects of a bumper mosquito problem. As well as talking about the prospects of an increase in mosquito-borne disease risk, it was a great opportunity to talk about personal protection measures.

There were some radio, print and tv spots that provided opportunities to talk about how to choose and use the right repellents.


In 2015 I published a paper in the Medical Journal of Australia explaining that health authorities need to provide more guidance on how the community can get mosquito repellents working more effectively.

Typical health warnings and media release from health authorities (usually limited to grabs on news bulletins) but when there is an opportunity to do longer form radio interviews, there is a chance to put an emphasis on aspect of public health messages. The hook to get these longer spots is giving more than just warnings, by mixing up some interesting things about mosquitoes, you can catch a little extra attention and sneak in the public health messages between the fun and fascinating facts about mosquitoes!

One news outlet was really insistent in grabbing a hold of me for some comments ahead of the evening bulletin. They even sent a crew to meet me in the city while I was taking the kids along to the Sydney Festival!

Lesson learned: When doing tv for the evening news, it is ok to wear a t-shirt, shorts and runners just so long as you have a rain jacket handy to make you like like you could have just stepped straight out of the wetlands!


From African forests to South American cities

While many of us were keeping our eyes on the developing outbreak of mosquito-borne Zika virus in South America towards the end of 2015, it wasn’t until February 2016 that the situation really grabbed the attention of the world’s media.

In late January, I published a piece at The Conversation titled “Does Zika virus pose a threat to Australia?” It prompted a little interest but it was the media conference coordinated by University of Sydney Media and Communications together with Australian Science Media Centre (AusSMC) that coincided with the announcement of the World Health Organization that the Zika virus outbreak was a Public Health Emergency of International Concern.

Together with colleagues from the University of Sydney’s Marie Bashir Institute of Infectious Disease and Biosecurity, I spoke at a media conference broadcast nationally on ABC News 24. There was a huge amount of media stories stemming from this media conference with over 500 individual articles identified across radio, tv, print and online. During the days and weeks following, I felt like I was spending more time at the ABC studios in Ultimo than I was in our lab! There were days when I spent hours on the phone doing radio interviews.

There were a couple of great longer form interviews that I really appreciated the opportunity to contribute to such as ABC Radio National’s Health Report and Rear Vision. There were also a couple of podcasts too, check out Science on Top and Flash Forward.

This flood of media requests also exposed me to a few more new experiences. There were live tv appearances on Sunrise, ABC News 24 and Sky News but probably one of the most interesting was my spot on Channel Ten’s The Project. It was interesting for a number of reasons.

Firstly, I was warned early on that one of the guests on the panel was comedian Jimmy Carr, a somewhat controversial figure notorious for jokes a little too close to bad taste. I’m not typically one to play the “wacky scientist” during interviews but what I was most cautious of was not being seen to be treating a very serious disease outbreak too lightly. I was determined to play the straight guy. In the end the interview turned ok but there were a couple of awkward moments that, luckily, ended up being edited out.

Secondly, simply doing the interview was unusual. It was a pre-recorded interview with me in a tiny room at the Channel Ten studio in Sydney and the panel in the Melbourne studio. I was sitting in front of a green-screen, staring down the camera with an earpiece blasting away in my ear. I have done live crosses before but they’re all been one-on-one interviews. This time it was with the panel and I found it incredibly difficult to get the feel for each of the panelists when they were asking questions. Missing that eye-to-eye contact was a disconcerting experience. Luckily, all turned out well in the end.

Lesson learned: Lots (I mean LOTS) learned while dealing with the interest in Zika virus! Probably another post in itself…but I would say that managing this volume of media wasn’t easy and it did eat up a lot of time (even though communicating public health messages is central to my “day job”) but this was important work.


A morning with Dr Karl!

When it comes to science communicators in Australia, there are few with a higher profile than Dr Karl Kruszelnicki. We’d spoken on a number of occasions about mosquitoes but I’d never actually met him in person before. “Dr Karl” invited me to hang out for a morning recording interviews for ABC News 24, ABC Local Radio and also guest on his national “Science Talk” segment on Triple J’s Mornings Show with Zan Rowe.

The experience of a behind-the-scenes perspective on Karl’s hectic schedule and how he manages the frenetic pace of work at the ABC was an eye opener. Doing the hour long segment on Triple J was great, enlightening to get questions from a slice of the Australian community I don’t usually cross paths with when doing the usual community engagement. I good reminder of just how much anxiety there can be within the community when news of international disease outbreaks occur. Not surprising given the thousands of Australians travelling to South America each month….with more to come later this year when the Rio Olympic Games kick off!

You can listen to the segment here and you can also follow Dr Karl on Twitter.

Lesson learned: From a public health perspective, this is a great reminder that the concerns and anxieties around infectious disease can change depending on the sector of the community you’re dealing with. The core messages may remain the same but you’ll always need to consider your audience when fine tuning your public health messages.


So, was all this worth it?

It was stressful. It was fun. It eroded much of my time that may have been spent in other ways but I see this as “doing my job” perhaps a little more than pure research scientists do. But how does all this convert into tangible metrics. How do you measure the reach and economics of all these media activities?

I’m fortunate to be supported by the University of Sydney media and communications team that helps out by providing some data on the metrics of my media activities each summer. What was all this time and effort worth?

Between November 2015 and Match 2016, I was quoted in over 160 media items. This adds up to a cumulative audience of around 8.9 million people, that is quite some reach! How much was it worth? Based on current advertising rates, about $1.6 million.

I’ve written before about how we can better value science and public health communication. Collecting these types of metrics can be useful for a range of purposes. Recently, I’ve been including media engagement as an “in kind” contribution to grant applications with valuation calculated on average media coverage that may be expected.

The lesson here is to take the time to record your media activities, not just so you have a list to demonstrate quantity but also so you can assess audience and value to your media activities. Work with your media and communications departments to see what extra information you can collect.

Got any other tips? Share them via Twitter!






Could a mosquito bite make you a Jedi?


On the eve of the release of Star Wars The Force Awakens, I’ve been revisiting bits and pieces of the previous six Star Wars movies. You know what stands out? I’ve been thinking about the possibility that wielding “The Force” may just be a symptom of parasitic infection!

Growing up with the original trilogy of Star Wars films, my perspective on “The Force” was entirely defined by Obi-Wan Kenobi’s explanation to Luke in A New Hope, “The Force is what gives a Jedi his power. It’s an energy field created by all living things. It surrounds us and penetrates us. It binds the galaxy together.”

I always thought of it as more a spiritual, rather than a scientific, thing. If I thought about it really hard, I could snatch that tv remote into my hand from across the room. Apparently it doesn’t quite work that way. I’d need to be infected with a parasitic pathogen. Midi-chlorians.

Midi-chlorians were explained to a young Anakin Skywalker by Jedi Master Qui-Gon Jinn in The Phantom Menace as “Midi-chlorians are a microcopic lifeform that reside within all living cells and communicates with the Force. We are symbionts with the midi-chlorians. Life forms living together for mutual advantage. Without the midi-chlorians, life could not exist, and we would have no knowledge of the Force. They continually speak to you, telling you the will of the Force.”

So, these intracellular microbes speak to us? Do they control the host? Are Jedi just doing the dirty work of midi-chlorians? I know midi-chlorians have sparked a sea of frustration among some Star Wars fans but lets just assume for a moment that the only reason Force users can do what they do is because they’re infected with special strains of these parasites.


How many times have you imagined you could snatch the remote from coffee table through nothing more than concentrated thought alone?

Can pathogens and parasites control their hosts?

We know that in a galaxy not so far away and not so long ago, parasites have been described that alter the behaviour of their hosts. See here  and here and here. From mind-controlling fungi to parasites that break down your fear of predators there are plenty of examples of how parasites change the behaviour of hosts to their own benefits.

There are insect symbiotes and mostly they’re beneficial. But when it comes to mosquitoes, microbes including viruses, bacteria, fungi and protozoa can influence their role in disease outbreaks.

Viruses, such as dengue, may even influence the behaviour of mosquitoes to increase the chances of their transmission to new hosts. Infection with a virus may also change the way mosquitoes respond to insect repellents. But when some mosquitoes are infected with an intracellular bacteria, a bacteria that’s not naturally found in this mosquito, their ability to transmit dengue viruses is blocked. It can also disrupt their blood feeding and reduce their lifespan.

Now, if mosquitoes are capable of transmitting blood-borne pathogens, could they also transmit midi-chlorians? If a mosquito bites you after its taken a blood meal from Yoda, Obi-Wan Kenobi or Luke Skywalker, could you start using the force? Is the ability to use the force a symptom of vector-borne disease?

Aedes aegypti

Itchy yet? Dozens of mosquitoes drinking in a mosquito researcher’s blood! (Image: Alex Wild)

Are there Medical Entomologists in the Star Wars universe?

I don’t know how many medical entomologists will be featured in The Force Awakens. According to Wookiepedia there are mosquitoes (or at least mosquito-like insects called Msqitoes) in the Star Wars universe but how would you go about working out if theses or any other blood feeding arthropods could transmit midi-chlorians between Jedi and us normal non-Jedi folk?

When investigating outbreaks of suspected mosquito-borne disease, there is a number of things to consider. Are there clusters of cases that may suggest localised exposure to mosquitoes? If there is widespread disease with little or no link to environments associated with mosquitoes, it is usually enough to suggest the pathway of pathogen transmission doesn’t include mosquitoes. But where there is evidence to suggest mosquitoes are playing a role, where to next?

Collecting and testing field collected specimens can provide some evidence. There are mosquito-borne pathogen surveillance programs in many parts of the world. They rely on collecting and testing adult mosquitoes but can also involve taking blood from wild or domestic birds to determine the circulation of mosquito-borne pathogens in the environment. However, just because a mosquito tests positive to a pathogen, it doesn’t mean it is spreading it to people.

There are thousands of mosquito species worldwide but relatively few effectively transmit mosquito-borne pathogens. For example, in Australia around 40 mosquitoes have been implicated in the transmission of Ross River virus but only one mosquito can transmit dengue viruses. Unless there is a specific relationship between the pathogen and the mosquito, the pathogen wont be transmitted.

Complex path of pathogens from host blood to mozzie spit

Mosquitoes aren’t like dirty syringes. They don’t transfer infected droplets of blood between people. Mosquitoes must become infected with the pathogen before it can then pass it on. Taking a virus as an example, the virus must be ingested by the mosquito together with a blood meal from an animal and then the virus must pass into and out of the cells lining the insect’s gut before spreading throughout the body of the mosquito. Once the salivary glands are infected (a process that takes about a week), the virus is passed on through the spit of the mosquito when it next bites (when feeding on an animal, a mosquito will inject some saliva to get the blood flowing).

Not all mosquitoes can transmit all mosquito-borne pathogens. Mosquitoes cannot transmit non-mosquito-borne pathogens. That’s why mosquitoes don’t spread Ebola virus.


For a mosquito researcher, surely Dagobah is top of the list of fantasy field trip destinations! There has to be plenty of mozzies on this swamp covered planet! (Image: Star Wars)

How would you test the ability of mosquitoes to transmit midi-chlorians?

Firstly you need some blood feeding mosquitoes. If there was anywhere in the Star Wars universe where mosquitoes could be found, surely it is Dagobah. The whole planet is essentially covered in wetlands. Once you’ve got the mosquitoes, now all you need is some midi-chlorian-filled blood.

Expose caged mosquitoes to a mix of blood and midi-chlorians (or ask a Jedi to kindly volunteer their arm). For those mosquitoes that feed, they can be put aside and kept alive for as long as possible. Every few days, mosquitoes are removed and tested for infection. Legs and wings can be removed from the mosquito and tested separately from the body. If they’re positive, it indicates the virus has spread through the body of the mosquito.

Next, the proboscis of the mosquito can be inserted into a micro-capillary tube filled with growth media. Once inserted into the liquid, the mosquito will instinctively feed and expectorate saliva. The saliva and growth media mix can then be tested for the presence of virus. If this mix is positive, it indicates the mosquito is transmitting the pathogen.


Known as “vector competence” experiments, studies investigating the ability of different mosquito species to transmit different pathogens help build up a profile of each mosquito and its potential role in the spread of local and exotic mosquito-borne pathogens.

Studies of this nature have been conducted for many, many mosquito species worldwide and many, many different pathogens. Here is a recent example of a study conducted to determine how the transmission of a strain of West Nile virus by mosquitoes influenced an outbreak of mosquito-borne disease in horses.

Things can start to get a little more complicated when you take into account the interaction between the host (e.g. an animal) and the pathogen, the level of viremia that may develop and the propensity of the mosquito to bite people. For example, some mosquito species may be very susceptible to infection and effective at transmitting a pathogen but if those mosquitoes prefer to only feed on birds, the risk to people are generally much lower.

The take home message from all these studies is that the interactions between pathogens, mosquitoes and the animals and people carrying the pathogens are complex. When assessing the risk of mosquito-borne disease outbreak, designing more effective mosquito-borne pathogen surveillance programs or developing strategic public health responses, it is critical to understand the ability of local mosquitoes to transmit pathogens.

In theory, a mosquito taking a blood meal from a Jedi whose blood contains a high concentration of midi-chlorians could potentially pass on some Force-inducing infections to other people. Makes you wonder why Yoda was hanging out in a swamp planet?

Disclaimer: There is little doubt the issue of midi-chlorians has been discussed, dissected and the implications for the ability to wield the force determined within Star Wars Expanded Universe/Legends literature. I know I’ve taken a little artistic license here but if you’re a Star Wars aficionado, please take this article for what it is, a fun way to communicate the science behind mosquito and mosquito-borne disease research.

Why not join the conversation on Twitter?

I’ll leave you with this great CDC video on immunization.

UPDATE! [9 January 2016] So, it seems that not only do mosquitoes potentially help make Jedi in the Star Wars universe but, as the The Force Awakens demonstrates, mosquito-inspired aliens are out and about in the bars and cantinas of the galaxy! Just in the remote chance you haven’t seen the movie, I won’t describe when and where these creatures pop up but they’re known as the “Dengue Sisters” and represent a sentient species of small insectoids known as Culisetto. They look pretty awesome (see photo below from “Star Wars: The Force Awakens Visual Dictionary” by Pablo Hidalgo)


Dengue Sisters from Star Wars: The Force Awakens Visual Dictionary (Thanks Cybergosh for the tip off)!

Perhaps I need to petition Hasbro to create a “Dengue Sister” action figure!