WorkSafe NSW recently issued a safety alert about Japanese encephalitis (JE), a rare but serious disease caused by the Japanese encephalitis virus (JEV), after it was detected in commercial piggeries in Southern, Western and New England areas of NSW as well as Queensland, Victoria and South Australia.
JEV is spread by the bite of infected Culex mosquitoes which are commonly found in NSW. Mosquitoes can become infected with the virus from biting infected animals such as pigs and some species of waterbirds.
The virus cannot be transmitted from human to human, by touching an infected animal or by eating animal products including pork or poultry products.
The alert said the risk of exposure is highest among people who work or live near piggeries that have tested positive for JEV.
Workers who work in close contact with pigs and/or are exposed to mosquitoes may be more at risk of infection unless they have been vaccinated for Japanese encephalitis or have prior immunity, and this may include:
Piggery workers and farmers
Pork abattoir and rendering plant workers
Pig transport workers
Veterinary personnel including veterinarians, vet nurses and students
Mosquito and animal surveillance, control and management workers such as environmental health officers and entomologists
Laboratory workers who work with specimens and virus cultures
People who engage in outdoor activities near significant mosquito populations, particularly near waterways (such as wetlands and national parks) in areas where JEV has been detected, are also at high risk.
The alert said most JEV infections are asymptomatic; less than 1 per cent of people infected will experience symptoms which typically include fever and headache. Occasionally JEV can cause severe illness with symptoms such as neck stiffness, disorientation, tremors, coma and seizures.
Among those who develop a severe infection, some will experience permanent neurological complications and death. Where symptoms do occur, they will usually develop 5 to 15 days after being bitten by infected mosquitoes.
If workers carry out work in an area where JEV is known to be present, the alert said it is unlikely that eliminating the risk of exposure to the virus will be reasonably practicable. This means that a PCBU must minimise the risk so far as is reasonably practicable.
The alert said control measures to prevent mosquito bites may include a combination of environmental and personal protective controls such as:
eliminate mosquito breeding sites around the workplace where possible, including removing any debris which may collect standing water
prevent mosquito entry at the workplace by closing windows, doors, vents and other entrances or covering them with insect screens
use insecticide sprays, vapour dispensing units (indoors) and mosquito coils (outdoors) to clear rooms or repel mosquitoes from an area.
protect workers and others at the workplace from being bitten by mosquitoes by:
ensuring they wear long, light-coloured, loose-fitting clothing and covered footwear when outside to minimise skin exposure,
providing an effective insect repellent (such as those containing diethyltoluamide (DEET), picaridin, or oil of lemon eucalyptus) and ensuring that it is applied correctly on exposed skin. Always check the label for reapplication times. Repellent may need to be reapplied more frequently during hot weather and after strenuous activity and perspiration as the duration of protection is reduced at these times.
ensuring any accommodation provided, including tents, is properly fitted with mosquito netting or screens.
provide information to workers on the risks and symptoms of Japanese encephalitis, and train workers in the use of controls including any personal protective equipment and repellents.