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DISEASE
RISK
Malarial
The risk of dying from Malaria in
short term travellers (2 - 6 weeks) is around 1 in 4000 if no preventative
medication taken.* A recent German study of travellers spending 2 -6 weeks in
Kenya showed that on average 20% had evidence of malarial antibodies (ie. were
bitten by malarial carrying mosquitoes)**
*Ref 1..www.who.int\ith\chapter07_02.html** Ref 2/. Travel seminar notes May 2000
Other
Common infections acquired by
travellers include those which follow ingestion of contaminated food or water.
Most of these are diarrhoeal diseases due to enteric pathogens such as
enterotoxigenic Escherichia coli, Salmonella, Campylobacter, Shigella and
Giardia species but infections with extraintestinal manifestations, such as
typhoid fever, amoebiasis, poliomyelitis, hepatitis A, brucellosis and
cysticercosis are also acquired this way.
Mosquito-borne infections, mostly malaria and dengue, are important causes of
fever in Australian travellers returning from southeast Asia, Papua New Guinea,
the Solomon Islands and Vanuatu. Japanese encephalitis occurs throughout Asia
but the risk to most Australian travellers is low. Yellow fever occurs only in
parts of Africa and Central and South America.
Vaccine-prevent able infections transmitted via the respiratory tract include
diphtheria, pertussis, measles, influenza, and invasive meningococcal diseas e.
Tuberculosis is mostly acquired by expatriates who live in high-risk areas for
long periods.
Viral
infections transmitted by blood transfusion or contaminated needles, such as
hepatitis B, hepatitis C and human immunodeficiency virus (HIV), may pose a
threat to some Australian travellers. In remote areas of some countries there is
the possibility that these viruses are transmitted by health-care workers using
unsterile medical equipment.
Travellers
may be exposed to other diseases such as rabies from dog (and other animal)
bites in countries such as Thailand, schistosomiasis after swimming in African
lakes, cutaneous larva migrans after sunbathing on contaminated beaches,
hookworm and strongyloidiasis after walking barefoot on contaminated soil and
leptospirosis following rafting or wading in contaminated streams. ( p 46. Australian Immunisation
Handbook, 8th Edition - 9/2003 )
Relative risks of
acquiring infections in developing countries |
High : > 1/10 travellers |
Moderate: <l/10->1/200 |
Low. <1/200->1/1000 |
Very low:<1/1000 travellers |
Diarrhoea
Upper respiratory infection |
Dengue
EnteroviraI infection Gastro-enteritis
Hepatitis A
Malaria (not taking preventative drugs)
Sexually transmitted diseases |
Amoebiasis, Ascariasis
Childhood Infections:- (Poliomyelitis, measles mumps,
chickenpox.) Hepatitis B, Hepatitis E TB, Typhoid fever
Leptospirosis
Strongyloidiasis
Trichuriasis
Tropical Sprue |
AIDS, Arboviral infections
Diphtheria, Echinococcus
Legionellosis, Meliodosis
Malaria (even whilst taking preventative drugs)
Q fever, Rabies
Schistosomiasis* Trichinosis
Trypanosomiasis
Viral haemorrhagic fevers
Yellow fever, |
* Schistosomiasis is on
the increase
Malarial
Prevention Medication Considerations
Reference 1/. "No drug is devoid of
side-effects, and chemoprophylactic drugs should not be prescribed in the absence of a
malaria risk. Not all travellers to countries where malaria exists should automatically
be prescribed prophylaxis. This is especially true for tourists and business
travellers who will visit only urban areas that are malaria-free."
"Both travellers and doctors should be aware that no
antimalarial prophylactic regimen gives complete protection. Falciparum malaria, which can
be fatal, must always be suspected if fever, with or without other symptoms, develops at
any time between one week after the first possible exposure to malaria and two months (or
even later in exceptional cases) after the last possible exposure.
The most important factors that determine the survival of patients with falciparum malaria
are early diagnosis and appropriate treatment." (International Travel and Health -
World Health Organisation 2000 pages72 & 75
Non Infectious Risks Occurring
in Overseas Travellers
Although travelling overseas particularly to developing
countries poses many potential health threats, it is important to remember that
considerable stress will be placed on you by factors such as long airflights,
disorientation with time zone changes, unfamiliar countries, roads and cultures. A large
Scottish study on deaths in overseas travellers highlights this point in revealing that
60% were due to effects of heart disease, smoking or alcohol, 21% due to traffic accidents
and only 4% were due to infectious diseases. Jet lag can slow your reflexes for
24>48hrs. It is best not to drive during this period
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