TROPICAL MEDICAL CONDITIONS

Living in Darwin and the Top End exposes people to a number of tropical diseases.
Our doctors are experienced with treating THESE conditions.

1. Allergic reactions to insect bites in the tropics.

(Advice from Dr David M. Welch of Stuart Park Surgery, 2016)

Allergic reactions to mosquitoes and sandflies (midges) are common in northern Australia and can be persistent and troublesome for some patients. Reactions are most commonly experienced when one first arrives into a new geographic location (tourists and newcomers), and gradually one builds up an immunity to the bites. Sometimes it takes a year for a person’s sensitivity to bites to settle, and occasionally a patient will suffer allergic reactions to bites for several years. Females of all ages tend to suffer bite allergies more commonly than males.

Scattered bite reactions on the face, upper and lower limbs are generally caused by mosquitoes, while multiple bites confined mainly to the legs are caused by sandflies (midges). Single bite reactions may be caused by spiders or mosquitoes. A severe reaction on the lower limb may be due to an unrecognised snake bite.

Sandflies live on tidal flats and are common in the Darwin and Palmerston regions. They bite most commonly at sunrise and sunset. Both mosquitoes and sandflies can be troublesome during spring tides, when they are flushed from low-lying areas and tidal flats, moving overland to higher ground. People may not notice they are being bitten, and are then puzzled by the allergic reaction they experience a few days later, with multiple itchy red spots.

Management of insect bites

  • (a) Preventing insect bites:

    Bites can be prevented by covering up with loose full-length clothing, which can be hot in the tropics.
    DEET repellent is best – there are various strengths of “Bushmans”.
    Avoid being out at sunset and on spring tides, or cover up more at these times.

  • (b) Treating the allergic component:

    Callamine lotion is cheap and readily available for less severe reactions and as a first-line treatment for children.

    Hydrocortisone cream is available without prescription, “over-the-counter”, and is safe for use on children and on the face. For severe reactions, prescription-only Diprosone cream and other strong steroid creams will need to be used, but must not be used on the face (sometimes they induce another type of rash on the face).

    Antihistamine tablets will control itching and swelling, and are available from pharmacies and supermarkets.

    Oral prednisolone (prescription only) is reserved for the most severe allergic reactions.

  • (c) Treating infected bites:

    Allergic reactions to bites result in skin inflammation and itching, opening the skin to the risk of infection. In order to avoid skin infections while suffering bite allergies, it is important to wash the whole body with an antiseptic soap (eg Sapoderm, Gamophen, Dettol etc) to reduce skin bacteria, and / or dab an antiseptic lotion (Mercurochrome, Betadine, Dettol etc) onto any open sores from the bites. The antiseptic can be applied first, followed by the application of any cortisone cream. Oral antibiotics may be required if a skin infection develops.

2. SCHOOL SORES (IMPETIGO), boils and other skin infections.

  • Bacterial skin infections are common amongst people living in the tropics, particularly during the wet season. This is because heat and high humidity allow bacteria to thrive on the skin surface.

  • Between 10 % – 25 % of the population carries Staphylococcus aureus, the bacteria causing most skin infections. Carriers have no symptoms until the bacteria penetrates the skin, causing an infection. Carriers may infect those around them.

  • Skin infections may develop following a break in the skin from a cut, abrasion, or an itchy rash. They may also occur without any break, travelling down the pores in the skin. This is particularly the case with children suffering impetigo (school sores).

  • Multiple surface infections causing blistering and sores are known as impetigo or school sores.

  • A deep infection with pus is known as a boil or abscess.

  • Multiple boils in the one location are referred to as a carbuncle.

here's the tip:

  • If you develop a skin infection necessitating a visit to the doctor and a prescription for antibiotics, then make sure you also use an antibacterial soap (e.g. Sapoderm, Gamophen, or Dettol) or an antibacterial wash (e.g. Chlorhexidine) for the following few months, particularly if it is during the wet season, to avoid a recurrence of the infection.

    This is because the antibiotic treatment kills the bacteria within the skin (the impetigo or boil), but does not prevent you continuing to carry the bacteria on the skin. If you do not use antibacterial soaps after suffering a skin infection (when living in the tropics), it is common for a small scratch or break in the skin at a later date to become infected again.

  • When living and working in the tropics in the long term, the risk of bacterial skin infections can be greatly reduced by regularly using an antibacterial soap (e.g. Sapoderm, Gamophen, or Dettol) or an antibacterial wash (e.g. Chlorhexidine). Those people who are allergic to soap can generally tolerate Chlorhexidine.

3. Tropical Ear Infection (otitis externa)

(Advice from Dr David M. Welch of Stuart Park Surgery, 2016)

  • Tropical ear infection is commonly acquired during one’s first stay in the tropics, particularly during the wet season (November to April) and after swimming. It is caused by an overgrowth of the normal ear flora (bacteria and fungi) due to high humidity and subsequent high levels of moisture in the ear canal.

    Treatment usually requires a visit to the doctor for a prescription of ear drops (generally Sofradex or a similar preparation) and an examination of the ear to exclude other possible conditions. If the ear canal contains an excess of debris (wax, skin flakes, pus or fungus), this debris should be removed by the doctor or nurse if possible, even if it requires gently syringing the ear. Apart from the ear drops, the ear should be kept dry for a week. For kids, this means no swimming.

  • Severe tropical ear infection (with much pain and swelling of the ear canal) is often caused by a pseudomonas bacteria, and requires oral medication (e.g. Ciproxin) or injections of antibiotics. The problem with pseudomonas is that it is resistant to all the commonly-used antibiotics like Penicillin, Amoxycillin, Cephalexin and Erythromycin. Ciproxin is not on the PBS list for treating tropical ear infection, but can be prescribed on a “private” script. (The people who determine such rulings obviously don’t live in the tropics.)

  • Recurrent tropical ear infection is caused by the following conditions:

    1. Repeated exposure to moisture, particularly from swimming
    2. Inadequate drying of the ear canal after showering and bathing
    3. Underlying dermatitis of the ear canal



    1. Keeping the ears dry

    A common scenario in tropical northern Australia is when there is a family swimming pool, and the children suffer recurrent otitis externa. This can be overcome by:

    (a) Keeping one’s head out of the water when swimming (often difficult with young children).

    (b) Pouring baby oil into the ears prior to swimming. The oil coats the ear canal and helps to repel water.

    (c) Using a spirit ear drop immediately after swimming – described in the next section.

    2. Inadequate drying of the ear canal after showering and bathing


  • In a southern temperate climate, the ears quickly dry naturally after swimming and showering, and most people are not troubled by otitis externa. There, the condition is known as “swimmers ear” because it is most common amongst swimmers.
  • People living in the tropics (which includes Darwin and the Top End of Australia) frequently suffer otitis externa and quickly learn to be meticulous about drying their ears after swimming and showering in order to prevent infections.
  • First, excess water can be drained from the ears simply by tipping the head to each side for a few seconds.
  • Next, a towel or tissue can be held to each ear to mop more water.
  • If needed, a tissue spear can be made and gently inserted to mop up more water. (A tissue spear is made by pulling and twisting the edge of a tissue to produce a small cone of compressed tissue.)

    For those who are particularly prone to recurrent tropical ear infections, the use of spirit ear drops is advised. Spirit ear drops come in three forms:

    (i) Commercial preparations such as Aqua-ear.

    (ii) Chemist’s formulae made by some pharmacies.

    (iii) By making your own ear drops, you will never run out. This is the ideal situation for families with swimming pools when children and adults may be prone to ear infections. A simple formula is 50% methylated spirits and 50% boiled water (allowed to cool, of course). This is much stronger than Aqua-ear, and can also treat an early infection, though it tends to sting once the ear is inflamed. If this is too strong for the kids, make the methylated spirits component weaker. If it stings, it suggests there is an infection, so one may wish to change over to Sofradex to treat the infection.
    The use of 50% methylated spirits and 50% water has been my family remedy for preventing ear infections for over 35 years of living in Darwin.

    3. Underlying dermatitis of the ear canal

    People suffering recurrent otitis externa (tropical ear infection) often find one particular ear causing the problem. Their doctor has examined the ear and told them there is a white fungal growth, and antifungal ear drops have been prescribed, but the ear continues to feel blocked and there is occasional pain. The ear discomfort persists or recurs for many months.

    The problem here is that a doctor with limited experience in tropical medicine is often unaware of dermatitis of the ear canal, which can appear quite different to dermatitis of the skin. On the skin, dermatitis is often dry and flaky. In the ear canal, it will appear dry and flaky when air humidity is low during the dry season, but during the wet season in tropical Darwin and northern Australia, the flakes of lifting skin fill with moisture and become thick soggy layers, often mistaken for a fungus. (When white fungus does occur, it appears as fluffy raised spores, due to Candida albicans.)

    Dermatitis often affects just one ear, which will be itchy and have flake, in a similar way that dermatitis of the skin often affects only one part of the body.

    The correct management of otitis externa caused by underlying dermatitis of the ear canal includes:

    (i) Ear toilet, meaning that the ear canal needs to be cleaned out (by the doctor or nurse).

    (ii) Use of steroids: Any steroid ear / eye drops can be applied to the ear canal to treat mild dermatitis. However, persisting infected dermatitis will probably require packing with a steroid-containing ointment such as Kenacomb, which often brings about a cure. The pack is applied by the doctor and needs to be changed every few days (e.g. Tuesdays and Fridays), with treatment continuing several weeks until the ear canal returns to normal.

4. Molluscum Contageosum (“tropical warts”)

Small clear vesicles common on children living in Darwin. The most common site is on the sides of the chest, under the arms. Click here for more information.

5. Tinea versicolor (Pityriasis versicolor or “white handkerchief”)

A fungal infection that removes pigment from the skin, leaving pale or whitish patches. Occasionally it does the opposite, producing darker, brownish patches. The most common sites are on the upper chest and upper back. It tends to recur after a single treatment, so the trick is to repeat the treatment every month for several months.

6. Mosquito-borne tropical viruses.

Download information sheets FRom N.T. health. Note: download can be slow.

Ross River Virus pdf icon
Barmah forest virus pdf icon

7. SCABIES.

Scabies, caused by a mite, is common throughout the Northern Territory and especially in the warm tropical north. It typically causes itching around the fingers, elbows and buttocks, and is worse at night. Any part of the body may be affected, except for the head and neck. A Northern Territory Department of Health fact sheet is available. Note: download can be slow.

SCABIES pdf icon

8. head lice and nits.

Head lice (small biting insects) and nits (the eggs) are common in the tropics. Two Northern Territory Department of Health fact sheets are available. Note: download can be slow

head lice and nits pdf icon
head lice advice pdf icon

9. hand, foot, and mouth disease

Although not a tropical disease, Human Hand Foot and Mouth Disease is common in Darwin. It is often mild – no worse than the common cold – and is diagnosed by the presence of small red spots or blisters on the palms and soles, and blistering of the tongue and inside the mouth. Complications are uncommon, and treatment is essentially symptomatic, with oral paracetamol to provide pain relief, and fluids to prevent dehydration. A Northern Territory Department of Health fact sheet is available. Note: download can be slow

hand, foot, and mouth disease pdf icon