Ross River Virus Infection
Updated: February 2001
Know before you go!
Infectious diseases not necessarily common in Canada can occur and may even
be widespread in other countries. Standards of hygiene and medical care may
differ from those at home. Before departure, you should learn about the health
conditions in the country or countries you plan to visit, your own risk of
disease and the steps you can take to prevent illness.
The risk is yours
Your risk of acquiring a disease depends on several factors.
They include: your age, gender, immunization status and current state
of health; your itinerary, duration and style of travel (e.g., first
class, adventure) and anticipated travel activities (e.g., animal contact,
exposure to fresh water, sexual contact); as well as the local disease
situation.
Risk assessment consultation
The Public Health Agency of Canada strongly recommends that
your travel plans include contacting a travel medicine clinic or physician
6 to 8 weeks before departure. Based on your individual risk assessment,
a health care professional can determine your need for immunizations
and/or preventive medication (prophylaxis) and advise you on precautions
to avoid disease. We can help you locate a travel
medicine clinic closest to your home.
Some facts from the experts
The information below has been developed and is updated in consultation
with Public Health Agency of Canada's Committee
to Advise on Tropical Medicine and Travel (CATMAT). The recommendations
are intended as general advice about the prevention of measles for Canadians
travelling internationally.
Disease profile |
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Ross River virus (RRV) infection, or epidemic polyarthritis, is a viral
infection spread by infected mosquitoes. Fewer than one in three humans
will become infected after being bitten by an infected mosquito. It generally
results in a self-limiting flu-like illness, but it can cause long-term
joint pain and fatigue. The virus causing RRV infection is a member of
the Togaviridae family of viruses.
Transmission
Ross River virus infection can be transmitted to humans
by the bite of an infected mosquito. A variety of mosquito species can
transmit RRV, biting day and/or night.
For instance, in Australia the following species have
been found to be RRV carriers:
- Aedes vigilax, a salt marsh mosquito, bites day and night.
- Aedes normanensis, a flood water mosquito, bites by day in
the shade and at night.
- Culex annulirostris breeds in shallow water and bites after
sundown and at night.
- Aedes notoscriptus, found only in urban areas where it breeds
in artificial receptacles, bites during the day in the shade and at
night.
Ross River virus infection cannot be passed from person
to person.
Geographic
distribution and incidence trends |
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Ross River virus infection is found in all States and Territories of Australia,
but occurs more often in the northern States and in coastal areas. Infection
can occur year round, but is more common from late November to the end
of April during the wet season when mosquito activity increases. Ross River
virus is also found in Papua, New Guinea, areas of Indonesia and the Western
Pacific islands.
Symptoms |
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Incubation of the disease following a bite of an infected mosquito varies
from 3 days to 3 weeks with symptoms developing within 7 to 14 days. Symptoms
of RRV infection vary person to person, but commonly include painful and
swollen joints, sore muscles, aching tendons, skin rash, fever, fatigue,
headache and swollen lymph nodes. Less common symptoms include sore eyes,
sore throat, nausea and tingling in the palms of the hands and soles of
the feet. Some individuals will experience reoccurring symptoms, especially
joint pain, fatigue, lethargy and depression that may continue for up to
1 year following infection. Symptoms disappear eventually and leave few
or no after-effects. Children are less troubled by the symptoms of RRV infection
than adults; the disease is usually milder and runs a shorter course. Most
people who have been exposed to RRV are immune for life.
Treatment |
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There is no vaccine and no specific treatment for Ross River virus infection,
but treatment of symptoms can reduce discomfort. Medical treatment is aimed
at easing joint pains and swelling, and minimizing fatigue and lethargy.
Prevention and personal precautions |
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As there is no vaccine that protects against the Ross River virus, using personal
protective measures to prevent being bitten by an infected mosquito remains
the only means to reduce the risk of exposure.
Recommendations
The Public Health Agency of Canada strongly recommends that travellers
consult their private physician or a travel medicine practitioner to discuss
their individual risk of exposure to Ross River virus infection. If you
are travelling to RRV-endemic areas, you should take the following personal
precautions to avoid being bitten at any time.
Personal measures to avoid
mosquitoes:
Protective clothing:
- Wear clothing that reduces the amount of exposed skin.
- Wear light-coloured, long-sleeved shirts, long pants, socks and shoes
when outdoors between dusk and dawn (note: dark colours attract
mosquitoes).
- Impregnate all clothing with 0.5% permethrin to make them repellant.
Screens and bed nets:
- Sleep inside screened areas, under a mosquito net or in an air-conditioned
room.
- Use bed nets that are rectangular in size, impregnated with permethrin
every six months and tucked tightly under the mattress before
dusk (note: treated bed nets are available in Canada).
Insect repellent:
- apply DEET-containing insect repellent to exposed skin when outdoors
between dusk and dawn.
Of the insect repellents registered in Canada, those containing
'N, N diethyl-m-toluamide' (DEET) are the most effective. Although the concentration
of DEET varies from product to product, repellency rates are largely equivalent.
In general, higher concentrations protect for longer periods of time, but
there is little advantage in the duration of repellence with DEET concentrations
greater than 50%, and there may be additional risk of toxicity with higher
concentrations. New micro-encapsulated products containing 33% DEET are
registered in Canada, and they should provide up to eight hours of protection.
Children and DEET
In rare instances, application of insect repellents with DEET has
been associated with seizures in young children (14 cases have been reported
in over 30 years of DEET use and billions of applications every year). The
actual concentration of DEET varies among repellents and can be as high
as 95%. However, repellents with DEET concentrations of 10% are very effective
and should last 3 to 4 hours. For children, DEET in a concentration of not
more than 10% should be applied sparingly to exposed surfaces only and washed
off after children come indoors.
The likelihood of adverse reactions can be minimized by
the following precautions:
- Apply repellent sparingly and only to exposed skin.
- Avoid applying high concentration products.
- Avoid applying repellents to portions of children's hands that are
likely to contact the eyes or mouth.
- Never use repellents on wounds or irritated skin.
- Wash repellent-treated skin after children come indoors. If a reaction
to insect repellent is suspected, wash treated skin and seek
medical attention.
In Canada, DEET products are not recommended for use in children less
than 2 years of age. The risk of DEET use vs. the risk of exposure to
life-threatening mosquito-borne diseases must be assessed by an individual's
physician or travel medicine practitioner. For more information on insecticide
use, go to: Safety
Tips on Using Personal Insect Repellent .
Some things to think about... |
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Fewer than one in three individuals will become infected with Ross River
virus infection after being bitten by an infected mosquito. However, there
is no vaccine against RRV. Using personal protective measures to prevent
being bitten by an infected mosquito remains the only means of prevention.
For more information...
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