A typical day in environmental health - a Friends ‘My Place’ story

  • Mosquito trap. Andrew Waters collecting blood samples from a chicken
  • Collecting mosquito larvae by the river.

Photos: Andrew Waters

As an environmental health professional working for the local council in Broome, Western Australia, my working day can be summarised as one of protecting the environment from the effects of human activity and protecting people from hazards in their environment.

In practical terms this means: ensuring drinking water is safe to drink and waste water (sewage, sullage) is safely disposed of; that the food people buy is safe and suitable to eat; and that mosquito borne viruses are kept at bay through monitoring and control of mosquitoes. On occasions environmental pollutants such as asbestos containing materials, and noise, dust, even light – escaping from one property and affecting residents of neighbouring properties – cause concerns and require investigation and control.

Looking at mosquitoes, in Broome and the Kimberley region there are four significant diseases that can be spread to humans by mosquitoes. The most well-known are Ross River Virus and Murray Valley Encephalitis (MVE). Ross River Virus can be debilitating for weeks or even months and MVE can be fatal in severe cases. There is no cure or vaccination for either. Prevention is the only approach.

Each week I visit a number of sites where water can gather to check for mosquito larvae. If there are larvae present then the water is treated with one of a choice from three methods – a surface ‘oil’ which leads to their suffocation, a hormone mimic which acts as a growth inhibitor preventing them from progressing to the adult mosquito stage, or a bacterial spore for a bacterium which specifically damages the larvae’s digestive system, killing them.  

Then once per month (or twice per month in the wet season), I visit a dedicated flock of domestic chickens and take blood samples from which the pathology laboratory determines if they have been exposed to MVE. New positive results indicate that the virus is active in the environment. Birds are the main host for MVE and Broome is on Roebuck Bay which is a feeding ground for thousands of birds on their annual migratory flight path between Siberia and Antarctica.  

Finally, when adult mosquitoes are active in the community and causing nuisance to people, I will set traps for adult mosquitos. The catch is frozen and then the individuals are looked at under a microscope to determine the species. Not all mosquitoes transmit diseases to people, and knowing which species are active helps determine if adulticide treatments are worthwhile, and gives information on where the larvae might be coming from so larvicide can be used. Some mosquitoes breed in dirty water, some in clean fresh water and some in salty or brackish water. Some breed in open water bodies and some in contained water such as plant pot saucers, discarded tyres or bromeliad plants. Detective work is necessary.

Regardless of this effort there will always be mosquitoes around us depending on the season so the key messages to people are: cover up – wear long sleeves and loose fitting clothes when mosquitoes are active; clean up – places in your yard where water can collect and put sand in pot plant saucers; and use repellent. Repellents containing DEET (diethyltoluamide) or picaridin have been shown to repel mosquitoes.

Showcasing the diversity of life in rural and remote Australian, in the Friends 'My Place: where I live and work' series, members of Friends of the Alliance talk about their life and work and what's special about where they live.


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