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Department of Medical Entomology |  |
| ? Frequently Asked Questions ? |
Mosquitoes
Can mosquitoes transmit AIDS or hepatitis?
Does Ross River only occur in northern Australia?
Can I get Ross River disease in Sydney?
How do I prevent mosquito bites?
How do I treat mosquito bites to stop the itch?
How many species of mosquitoes are there?
How long does a mosquito live?
Mosquitoes are coming into the house, how do I stop them?
Will Global Warming (from the Greenhouse Effect) result in
an increase in mosquito-borne diseases?
Are mosquitoes from wetlands a health or pest risk?
Ticks
Is there Lyme disease in Australia?
I left the head of the tick behind, what should I do now?
Is it ok to use kerosene on the tick to remove it?
How do I remove a tick?
How do I prevent tick bite?
How
do I treat tick bite?
I have ticks in the backyard, how can I get rid of
them?
I had a severe reaction after removing a tick, what can
I do?
Do ticks jump?
How long does a tick have to be attached before paralysis
occurs?
Mites
What is scabies?
Do dogs carry human scabies?
Can bird mites burrow under the skin?
How do I get rid of a bird mite infestation?
Lice
Do head lice only affect dirty children?
Do I need to treat all family members if one child has
head lice?
Can I get pubic lice from dogs, toilet seats or towels?
Spiders
What symptoms result from the bite of a
White-tailed spider?
Other
Something seems to be biting me and
causing a severe itch, what can it be?
Send your FAQ to Stephen L. Doggett
Mosquitoes
Can mosquitoes transmit AIDS or hepatitis?
No, despite testing by several
laboratories, no conclusive evidence has been found to suggest that mosquitoes can
transmit these diseases. The virus that causes AIDS can not survive in the mosquito like
some other viruses such as Ross River virus. The mouthparts of a mosquito (the proboscis)
are not like a syringe, i.e with a single channel where blood can go up and down. Rather,
the proboscis has separate channels for saliva flow and blood intake, hence these diseases
are not likely to be transmitted in the manner they can be with syringes. (BACK)
Does Ross River only occur in northern Australia?
No, the disease occurs right across
Australia in all states, including Tasmania. The locations that have little disease
include those areas that are very dry such as the deserts (although disease transmission
may occur after heavy rains), much of the mountain range of eastern Australia, and the
major southern cities (although there may be cases on the outskirts). (BACK)
Can
I get Ross River disease in Sydney?
The chances are small. Within Sydney there are none
of the animals (such as kangaroos) that act as the major host for the virus. However,
there are known mosquito vectors present and with infected people returning from country
areas where the virus is present, it is possible that human-mosquito-human transmission
(normally the cycle is animal host-mosquito-human) may occur, although this has never been
documented. Occasionally outbreaks of Ross River virus occur on the fringes of major
cities, where both mosquito vector and animal hosts occur together, and this has happened
in Perth, Brisbane, and in Sydney in the summer of 1996-97. (BACK)
How
do I prevent mosquito bites?
Prevention of mosquito bites can be achieved either
through undertaking active mosquito control or by the use of personal protective measures.
A variety of active mosquito control measures are available, including habitat
modification in order to reduce water availability for breeding of the larval stage,
through to the use of appropriate insecticides for controlling the larval or adult stage.
These are large scale control measures which can only be undertaken by government bodies
such as local councils. On a small scale, householders can ensure that their own backyard
does not contain water holding containers which can provide suitable mosquito larval
habitats (e.g. undrained pot plants, blocked gutters, disused bottles, old tyres, etc).
Personal protective measures include: avoiding known mosquito infested areas, especially
at dawn and dusk when mosquitoes are most active; ensuring that houses are adequately fly
screened; using insect repellents that contain the chemical DEET, and reapplying it
regularly; and wearing long sleeved shirts and pants. Other preventative measures include
government based programs that undertake mosquito monitoring and virus surveillance from
mosquitoes. These programs aim to act as an early warning system for virus activity by
monitoring weather patterns, mosquito populations and viruses such as Ross River, Barmah
Forest, Murray Valley encephalitis and Kunjin. In New South Wales, such a program has been
running for several years at the Department of Medical Entomology at Westmead Hospital. (BACK)
How
do I treat mosquito bites to stop the itch?
Cold water and ice can be useful, although ice
should not be applied directly to the skin. A variety of commercial preparations can be
obtained from the chemist including Eurax® and Stingose®. In
severe cases, oral antihistamines may have to be administered and if symptoms persist, a
physician should be consulted. (BACK)
How
many species of mosquitoes are there?
In Australia there are around 400 species but only
approximately 10 are commonly abundant and represent a serious pest threat because of
their nuisance biting or their ability to transmit disease. (BACK)
How
long does a mosquito live?
This varies with the mosquito species and the time
of the year. Some species may only live for less than a week, while others can live for
several months over the winter months. (BACK)
Mosquitoes
are coming into the house, how do I stop them?
Intact flyscreens on all windows and doors will
prevent mosquitoes entering. The main species that tend to enter houses are those that
breed around houses. Thus it is important that any container that can hold water be
emptied or removed. (BACK)
Will
Global Warming (from the Greenhouse Effect) result in an increase in mosquito-borne
diseases?
This is very difficult to determine. Currently
there are different theories as to the level and amount of climate change. Some models
predict large changes in rainfall patterns, while other predict small changes. We may
expect with increases in rainfall there would be an increase in mosquito numbers and a
subsequent increase in mosquito-borne diseases, however this may not be the case. The
biology of mosquito-borne diseases is a very complex issue and involves the mosquito
vector, reservoir hosts and even sociological factors. In some areas, an increase in
rainfall may even lead to a decrease in mosquito numbers! All we can be certain of, with
global warming, is that there will be a change in the amount and distribution of disease,
but to what extent, it is not known. (BACK)
Are
mosquitoes from wetlands a health or pest risk?
They can be under certain circumstances, this is described in detail in the Fact Sheets on
"Mosquito Production and Management - Saline
Wetlands, Freshwater and Constructed Wetlands, and Irrigation Wetlands". (BACK)
Ticks
Is
there Lyme disease in Australia?
There is some debate as to the presence of Lyme
disease in Australia. Some workers believe that it is here. However, the most
comprehensive tick survey undertaken in Australia to date, found no conclusive evidence
for any spirochaete bacteria that may be responsible for the disease (see fact sheet on Lyme Disease for more information). If Lyme Disease
is present in Australia, then that it must be very rare. (BACK)
I
left the head of the tick behind, what should I do now?
When a tick is removed, commonly a portion of the
head or the mouthparts are left behind. Generally this does not cause any problems as the
head of the tick will fall out as the skin sloughs off in time. However, if a local
reaction does occur, then a physician should be consulted. (BACK)
Is
it ok to use kerosene on the tick to remove it?
No, this often causes the tick to inject its saliva
into the host and can increase the risk of transmitting disease causing organisms, or
increase the risk of death from paralysis. (BACK)
How
do I remove a tick?
Insect repellent may be applied to the tick, which
will kill it. The tick should be removed with the aid of a pair of fine tipped forceps;
the tick needs to be grasped as close the skin of the host as possible, and then forcibly
removed. (BACK)
How
do I prevent tick bite?
A variety of methods exist to reduce the
possibility of tick bite and prevention is best achieved via some form of personal
protection. People who bushwalk in tick infested areas need to use an insect repellent,
particularly one containing the chemical DEET, and this should be applied regularly to
clothing. Wearing light coloured clothing is useful as ticks can be more easily spotted.
Bushland locations which are highly tick infested should be avoided. (BACK)
How
do I treat tick bite?
Treatment is the same as that for mosquitoes; cold
water and ice can be useful to relieve itching, although ice should not be applied
directly to the skin. A variety of commercial preparations can be obtained from the
chemist including Eurax® and Stingose®. In severe cases, oral
antihistamines may have to be administered and if symptoms persist, a physician should be
consulted. (BACK)
I
have ticks in the backyard, how can I get rid of them?
This is very difficult, if not impossible to
achieve. As ticks are very susceptible to desiccation, removing trees and shrubs will
increase the amount of light to the ground, thereby decreasing the humidity levels and
making conditions unfavourable for tick survival. Often this involves considerable
environmental destruction and is not advisable. The presence of ticks in an area indicates
that there are native animal hosts present (usually bandicoots) and this suggests that the
environment is natural and healthy. If ticks are present, then it is best to undertake
tick avoidance measures as discussed above. (BACK)
I
had a severe reaction after removing a tick, what can I do?
If an individual reacts severely to a tick bite,
then potentially a life threatening anaphylactic reaction may occur in the future and tick
avoidance measures must be a priority. Until recently it was possible for such people to
be desensitised, however this is no longer possible do to the non-availability of
reagents. (BACK)
Do
ticks jump?
No. People often think that because a tick often
attaches in the head, that the tick has jumped out of the trees. As ticks are susceptible
to desiccation, they tend not to climb very high in the vegetation. Once on a host, the
tick may take several hours before finding a site to attach to, which is often on the
head. Ticks do not have legs that are adapted for jumping. (BACK)
How
long does a tick have to be attached before paralysis occurs?
This varies with individuals and some may not even
experience paralysis with a fully engorged tick. Generally symptoms of paralysis start
showing 2-4 days after the tick has attached. (BACK)
Mites
What is scabies?
Scabies is a condition caused by the mite Sarcoptes
scabiei, which burrows under the sensitive sections of skin, causing severe
irritation. Transmission is usually from one infected individual to another. Diagnosis can
only be achieved with a skin scraping, which is examined by microscopy, Scabies is easily
treated with various readily obtained preparations from chemists. (For more information
see the Scabies fact sheet). (BACK)
Do
dogs carry human scabies?
No, scabies mites are generally host specific and
human infections are typically acquired from another infected human. (BACK)
Can
bird mites burrow under the skin?
No, bird mites do not do this. Bird mites will
repeatedly "test bite" but do not feed continuously. (BACK)
How
do I get rid of a bird mite infestation?
Bird mite infestations originate from birds that
are nesting within the house. The mites become a problem when the young birds fledge and
the mites in the nest search for a new host to feed on. It is thus important that all
nesting material is removed, sealed in plastic bags and discarded, and all access points
for birds into the roof be sealed to prevent further reinfestations. (BACK)
Lice
Do
head lice only affect dirty children?
No, all children are equally at risk of acquiring
head lice. Transmission occurs very easily through contact from one infected child to
another. Being clean does not prevent infection. (BACK)
Do
I need to treat all family members if one child has head lice?
Yes, head lice are very easily transmitted from one
family member to another. Not everyone will show signs of an infestation and thus all
members should be treated at the same time. Likewise all bed linen should be washed in hot
water and left to dry in the sun (or a hot clothes dryer). (BACK)
Can
I get pubic lice from dogs, toilet seats or towels?
No, pubic lice are host specific and are not a
parasite of dogs. Acquiring public lice from toilet seats is unlikely, although sharing
towels with an infested person can result in transmission. (BACK)
Spiders
What
symptoms result from the bite of a White-tailed spider?
Generally there is local pain, swelling and itching
at the site of the bite. There is some evidence that local skin ulceration can occur
although this is appears to be uncommon. (BACK)
Other
Something
seems to be biting me and causing a severe itch, what can it be?
This is very difficult to determine as there are
many things that can irritate, and individual reactions vary from person to person.
Insects may be the problem and there are a large variety that can bite (e.g. fleas, flies,
mosquitoes, bird mites, etc) or irritate (various urticating caterpillars). However,
humans are typically exposed daily to a huge variety of chemicals and other irritants, and
these could be cause of the problem rather than insects or mites. (BACK)
Send your FAQ to Stephen L. Doggett
