Some more on tropical diseases
Cholera, dengue and malaria are endemic in Sarawak. This section
gives a brief description of each disease, including method of transmission,
symptoms, treatment, and what you can do to protect yourself from
infection.
Cholera is an illness caused by ingesting bacteria from contaminated
food and water, or from direct contact with stool from an infected
person. It is not spread through the air. The incubation
period for the disease is between a few hours to one week.
Cholera may cause sudden severe watery diarrhoea which is usually
painless. Many cases may also involve vomiting, and some may develop
leg cramps. Most people will only have a mild episode of illness
that is similar to simple food poisoning, and they recover spontaneously.
Only 5% go on to develop full-blown symptoms of cholera, and 99%
of these will recover quickly with adequate fluid intake. When cholera
causes problems, it is because of fluid loss.
Cholera is very easily avoided. Simple hygiene is the most important
measure and will alone reduce the risk of catching cholera to virtually
nil. Boiling for a few seconds kills the bacteria, but they may
live for up to six weeks in ice.
How to avoid catching cholera
There are periodic outbreaks of cholera, and at such times, take
the following precautions to avoid catching the disease.
If you are eating at home:
- Make sure all foodstuffs are washed in clean, chlorinated water
- Cook food thoroughly
If you are eating out at a restaurant:
- Drink only water that you know is safe (boiled, chlorinated
or bottled)
- Drink other safe beverages, such as tea made with boiled water
and canned drinks
- Avoid ice unless you know it is made from clean water
- Eat only foods that have been thoroughly cooked and are still
hot, or fruit that you have peeled yourself
- Avoid undercooked or raw fish or shellfish, including umai
- Make sure all vegetables are cooked
- Avoid salads unless they are washed in clean, chlorinated water
- Avoid food and beverages from street vendors
Some protective steps to take:
- Ensure good personal hygiene - always wash your hands in clean
water before eating, and avoid handling or preparing food for
others if you have diarrhoea.
- Ensure good kitchen hygiene and make sure your food preparation
tools are washed thoroughly. If you are not sure of water quality,
boil it for at least two minutes.
- Wash hands thoroughly with soap and clean water after visiting
the toilet, or after contact with any person having diarrhoea.
- Keep towels separate and washed regularly.
- The stools from a person with cholera are very infectious. Any
mess should be cleared up with bleach. Bacteria from cholera will
stay in the stool for up to two weeks, so hygiene precautions
must stay in place for at least that length of time.
Treatment of cholera
If you get severe diarrhoea, particularly with a fever, see a doctor.
Small children are more likely to be seriously affected by diarrhoea.
Danger signs to look for that indicate severe dehydration and require
immediate medical attention are:
- Drowsiness
- Dry sunken eyes
- No pulse noticeable at the wrist
- Very thirsty but unable to drink
Cholera can be treated simply and effectively by immediate replacement
of the fluid and salts lost through diarrhoea. Patients can be treated
with an oral rehydration solution, a pre-packaged mixture of sugar
and salts mixed with water and drunk in large amounts. Adults may
require up to 20 litres of fluid in the first 24 hours. Severe cases
also require intravenous fluid replacement. Antibiotics shorten
the course and diminish the severity of the illness, but they are
not nearly as important as rehydration.
A vaccine for cholera is available. However, it gives only brief
and incomplete immunity and is not generally recommended. Hygiene
measures are more effective and much more important.
There are two distinct illnesses: Dengue fever and Dengue haemorrhagic
fever (DHF).
Dengue fever is a flu-like illness that affects infants,
young children and adults. It is unpleasant, but very rarely causes
death. Infants and young children usually have fever with a red,
blotchy rash that looks like measles. Older children and adults
may have either a mild flu-like fever, or the classical disease
characterized by sudden onset of high fever, severe headache, pain
behind the eyes, no appetite, muscle and joint pains, and red rash.
Many people who contract dengue fever think they simply have the
flu and make a complete recovery without ever discovering the true
cause of their illness.
Dengue haemorrhagic fever (DHF) is much less common,
but may have serious complications with high fever, bleeding, and
in most severe cases, collapse. The illness often begins like dengue
fever. Signs that then cause concern are:
- Severe continuous stomach pains
- Pale, cold, clammy skin
- Excessive thirst
- Frequent vomiting, sometimes with blood
- Rapid weak pulse
- Constant crying
- Restlessness
- Difficulty breathing
- Fainting
- Bleeding (nose, mouth, gums)
- Bruising.
If you have any of these, in addition to the symptoms of dengue
fever, see a doctor immediately. Even in moderately severe DHF the
patient will make a full recovery after the fever drops. DHF, if
treated properly, has a mortality rate of 1 to 2%. Untreated, the
mortality is much higher.
Some 2,500 million people - two fifths of the world's population
- are now at risk from dengue. WHO currently estimates there may
be 50 million cases of dengue infection worldwide every year. The
disease is now endemic in more than 100 countries in Africa, the
Americas, the Eastern Mediterranean, South-East Asia and the Western
Pacific. Dengue is present in Malaysia all year, but usually peaks
in August.
How to avoid catching dengue
There are four different viruses which cause dengue, and infection
by one does not offer protection against subsequent infection by
the other three. The viruses are spread only by the bite of the
Aedes egyptii mosquito, so if you can avoid mosquito bites
you are safe.
The Aedes egyptii mosquito is a small striped mosquito.
It prefers to bite in the early morning and late afternoon before
sunset. It likes to live inside houses. Its larvae grow in water.
The mosquito does not travel long distances and becomes infected
from biting people ill with dengue. These facts give us our main
methods of control.
To protect yourself:
- Wear shirts with long sleeves, trousers and socks
- Use insect repellants; those containing ~ 20% DEET (diethyl
toluamide) or permethrin are effective
- Avoid activities that expose you to bites
- Protect people with suspected dengue or fevers from mosquito
bites to prevent further spread
To protect your house:
- Use mosquito coils and electric vaporisers that help repel or
kill mosquitoes
- Spray inside house with fly spray (read the instructions)
- Place mosquito nets over beds
- Spray mosquito nets with pyrethroid insecticide to improve
their performance
- Install screens on windows to reduce the number of mosquitoes
in the house
To eliminate breeding sites:
- Remove rubbish around the house; Aedes egyptii like to
breed in old cans, bottles, tyres...
- Practice general hygiene to prevent spread of the disease
- Cover water containers
- Seal septic tanks or cover the water surface with polystyrene
beads
- Kill the larvae by chemical and biological means
- Ensure regular garbage collection
Treatment of dengue
See a doctor. There is no specific treatment for dengue fever, but
early treatment of DHF is very important and saves lives. The doctor
can diagnose the disease and complications by blood tests. There
is no vaccine currently available, but it is hoped that there will
be one within five years (from 1998).
Malaria is caused by protozoa parasites called plasmodium.
It is transmitted by bites from the anopheles mosquito, which
is the vector for the disease. The saliva in a mosquito's bite contains
infective forms of the parasite.The parasites pass into the blood
and into the liver, where the mature form develops. There are no
symptoms at this stage. The parasites then pass into the red blood
cells, where another form of the parasite multiplies and spreads.
Symptoms occur for the first time. Intermittent spiking fever often
occurs every couple of days. The person is often well between fevers.
What are the symptoms of malaria?
The incubation period for malaria is from a couple of days, to six
weeks in rare cases.The illness can vary in severity, from mild,
recurrent flu-like illness, through to multi-organ failure and death.
The main symptoms of malaria are:
- Fever
- Chills with sweating
- Headache
These symptoms come and go. Many other symptoms can occur:
- Abdominal pain
- Nausea
- Vomiting
- Diarrhoea
- Muscle pain
- Back ache
- Jaundice
If untreated, more severe symptoms may develop. Because the early
symptoms are non-specific, a blood test should be taken as soon
as possible if malaria is suspected so that treatment can start
immediately. Ideally, this test should be taken during a bout of
fever. Women's resistance decreases during pregnancy. Malaria is
more likely to occur and be more severe, and may increase the likelihood
of miscarriage or stillbirth.
Should I take antimalarial drugs while living in Miri?
There is malaria in Miri but in small amounts, and it is not worth
taking malaria prophylactics. Sabah has a bigger incidence of malaria.
Prophylaxis is advised in rainforest areas but not in major towns.
If you are going on a trip to the interior, and wonder whether or
not to take antimalarial drugs, discuss this with your doctor.
How to avoid catching malaria
The only way to catch malaria is to be bitten by an infected mosquito.
Mosquitoes breed in stagnant water, so any measures to reduce open,
stagnant water will reduce the number of mosquitoes. Spraying with
residual insecticide (insecticide which stays active for a long
time) is also important. The anopheles mosquito is mainly
active at dawn and dusk. The best way to prevent malaria is to reduce
personal exposure to this mosquito:
- Use insect repellent containing diethyl toluamide or
DEET
- Use mosquito nets impregnated with permethrin
- Fit wire mesh over the windows
- Use air conditioners
Treatment of malaria
If you think you have malaria, see a doctor. Treatment depends on
the type of malaria, the severity, and the area in which it was
contracted. If you live in a malarial area, you may develop minimal
resistance. There are currently no signs of a vaccine being developed
in the near future although it is a very important area of research.
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