Science students investigate Zika virus

  • Published on June 4, 2019
  • By Caroline O’Leary and Susan Gates

    Does Brisbane have mosquitoes that can spread Zika virus?

    Twelve intrepid Year 9 Science students from Indooroopilly State High School recently volunteered for a STEM immersion experience to find out.

    They were transported into the bushland education facility at the Toohey Forest Environmental Education Centre at the Nathan Campus of Griffith University to develop their skills in Biology.

    students use microscopes
    Angela, Ameera, Austin, Ayden and Ewan use microscopes to identify the species of adult mosquito.
    Releasing labelled mosquitoes
    Priya and Madison release labelled mosquitoes as part of a label recapture method of estimating mosquito population.

    Students started the day with a walk through the eucalypt and rainforest surrounding the Education Centre, and did investigations using the interactive exhibits inside the building.

    Research scientists from QIMR and the Queensland Department of Health explained their career pathways into a life of research.

    Students then entered the world of the rapidly spreading Zika virus. Zika virus is an emerging viral infection affecting people who live in areas where suitable mosquitoes that can spread the disease live.

    The bite of an infected female mosquito (males don’t bite people) seeking a high-protein blood meal before laying her eggs, can pass the virus to people. The virus may cause flu-like symptoms in some infected people, but the main problem is the birth defects that can appear in the babies of women bitten during their pregnancy. These babies can have microcephaly: a very small brain.

    Does Brisbane have the mosquitoes to spread this virus? Well, it’s up to the students to find out. The research project has extended into a community research project, in which citizen scientists will monitor the presence of these Zika-carrying mosquitoes across Brisbane.

    Our students participated in several activities, using techniques commonly used by the mosquito researchers.

    The first activity was to tag captured mosquitoes with a fluorescent powder which were then observed using a UV light.  The tagged mosquitoes were then released into Toohey forest.  The students learnt about the Mark-Release-Recapture method of estimating mosquito populations using the Lincoln Index (a ratio of tagged/untagged mosquitoes recaptured).  They also learnt about methods used to control mosquito populations, including the release of sterile male mosquitoes into an environment.

    Another activity focused on identification of mosquito species, in particular the Zika vectors Aedes aegypti and Aedes albopictus.  Students examined adult mosquitoes using stereomicroscopes, and learnt to recognise the distinguishing features of each species. They also learnt about the mosquito life cycle, and used a stereo microscope to observe and sketch the four main stages: egg, larva (wriggler), pupa (tumbler) and adult.

    PCR products
    Agarose gel electrophoresis tank for running PCR products to identify mosquito species. PCR products are pieces of copied DNA from the mosquito eggs.

    The first activity was to tag captured mosquitoes with a fluorescent powder which were then observed using a UV light.  The tagged mosquitoes were then released into Toohey forest.  The students learnt about the Mark-Release-Recapture method of estimating mosquito populations using the Lincoln Index (a ratio of tagged/untagged mosquitoes recaptured).  They also learnt about methods used to control mosquito populations, including the release of sterile male mosquitoes into an environment.

    Another activity focused on identification of mosquito species, in particular the Zika vectors Aedes aegypti and Aedes albopictus.  Students examined adult mosquitoes using stereomicroscopes, and learnt to recognise the distinguishing features of each species. They also learnt about the mosquito life cycle, and used a stereo microscope to observe and sketch the 3 main stages: egg, larva (wriggler), and adult.

    Students next learnt about the use of a DNA-based PCR method of mosquito identification.  This method uses the Polymerase Chain Reaction (PCR) to amplify a small piece of DNA isolated from mosquito eggs.  Each mosquito species has slightly different DNA, which produces different sized PCR products.  These products are analysed by agarose gel electrophoresis which sorts the products by size and allows rapid, automated identification of the species the eggs came from.  Our students were able to practice the techniques of loading and running an agarose gel in the laboratory.  This method will be used to identify eggs collected by our students, as part of the Zika Mozzie Seeker project.

    Students at work on the Year 9 Science Excursion.
    Students log their results on the STEM immersion experience.

    Finally students were introduced to the mosquito egg collection method that will be used in the Zika Mozzie Seeker project.  They practised an egg strip Manual Count activity, and were shown how to set up a mosquito egg trap at home which will be used to collect mosquito eggs.  The samples collected by students will be analysed by the researchers using PCR to determine the distribution and numbers of different mosquito species around SE Queensland.

    With their newly acquired skills in mosquito identification and mosquito egg counting techniques, these citizen scientists will be estimating mosquito egg numbers, and identifying mosquito breeding hotspots across Brisbane.

    Students will collect their mosquito egg samples, estimate their egg numbers, and send off their egg samples to have the species of mosquitoes that laid the eggs identified. Students will then discover who is breeding the most mosquitoes in their backyards, and if they are mosquitos that could carry Zika virus. Samples will come in over the next month, but if seasonal factors affect mosquito populations, the project may have to be resumed in summer.

    The mosquitoes believed to be the main risk vectors in Brisbane are Aedes species mosquitoes (Ae. aegypti and Ae. Albopictus).

    The first mosquito lives approximately 200km north of Brisbane but does not fly more than 200m and is very fragile so is unlikely to be spread by winds. However, this mosquito used to live in Brisbane about 50 years ago when water tanks without grids over tank entrance points were common. As water tanks disappeared from Brisbane so did this vector and Dengue fever. However, with the reintroduction of water tanks to Brisbane, and global warming, there is a risk this mosquito may return. These mosquitoes also transmit Zika virus or Dengue fever, both of which are serious diseases, so monitoring for these vectors is important for several reasons.

    The second mosquito of interest, Aedes albopictus, is in the Torres Strait, may also be introduced into Australia, and is likely to survive well in the Brisbane climate.

    Human cases with Zika virus have been diagnosed in Australia, however all cases appear to have been caught overseas. The problem is that if a vector bites such an infected person (and some infected people may not know they have the virus as the disease is very mild in some people) the virus may become established in the mosquito vectors in Australia.

    Aedes larva
    Aedes species larva (wriggler), viewed under a stereomicroscope. Lives in fresh water and feeds on plant material.
    About Zika
    • Zika virus disease is caused by a virus transmitted primarily by Aedes mosquitoes, which bite during the day.
    • Symptoms, which typically last for two to seven days, are generally mild and include fever, rash, conjunctivitis, muscle and joint pain, malaise or headache. Most people with Zika virus infection do not develop severe symptoms.
    • Zika virus infection during pregnancy can cause infants to be born with microcephaly and other congenital malformations. This is known as congenital Zika syndrome. Infection with Zika virus is also associated with other complications of pregnancy including preterm birth and miscarriage.
    • An increased risk of neurologic complications is associated with Zika virus infection in adults and children, including Guillain-Barré syndrome, neuropathy and myelitis.
    Caroline O'Leary
    Caroline O’Leary
    Caroline O’Leary

    BVSc MACVSc PhD Grad Dip Ed

    Caroline graduated as a Veterinarian from The University of Queensland, spending time treating pets and farm animals in Australia and the United Kingdom. Enjoying the James Herriot lifestyle, Caroline then decided to further develop her clinical skills by gaining Membership in the Australian and New Zealand College of Veterinary Scientists in the chapter of Canine Medicine. During this process Caroline bumped into the heady world of research, and went on to complete a PhD in Veterinary Pathology and Molecular Genetics. This foray focused on describing and investigating several inherited heart and kidney diseases affecting the unlucky but incredibly stoical English Bull Terrier. Caroline then joined The School of Veterinary Science at the University of Queensland, where she worked for 15 years conducting research into inherited diseases and cancers affecting several dog breeds, diabetes in cats, and developed a love for teaching. While Caroline has lectured to large groups of Veterinary students, she most enjoyed individual or small group teaching, and this has eventually led her into teaching Science in High School. Caroline has three teenage children, lots of animals, and keeps a toe in the world of Veterinary research.

    Susan Gates
    Susan Gates
    Susan Gates

    BVSC, Grad Dip Biotech

    Growing up in rural Queensland, Susan had a love of animals from an early age and developed a strong interest in Science during high school. She went on to study Veterinary Science at the University of Queensland. She worked in a small animal practice in Brisbane for a number of years before further study in the (then new) area of molecular biology at Queensland University of Technology (QUT), which led to a career in scientific research. She worked in research labs at the University of Queensland and Queensland University of Technology on a number of projects including the development of a patented DNA-based diagnostic test for genetic diseases, using cystic fibrosis as a model. After having three children, now aged 25, 22, and 16, she re-entered the workforce as a Science Operations Officer (Laboratory technician) at Indooroopilly State High School. She says the job has been very rewarding and a great way to continue her involvement in science in a family-friendly way. “I have been working here for more than 12 years, and every day brings something new.  I can honestly say it has been the most varied, interesting and rewarding job I’ve had.” she says.

Memberships & Associations

The Queensland Department of Education and Training: Trading Name, Education Queensland International CRICOS Provider Number: 00608A