Skin problems in the traveller
Eczema is often precipitated by or exacerbated by a change in climate. Heat and sweating can make eczema worse, and a cold, dry environment can also cause an exacerbation.
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1 Eczema is extremely common after travel
Eczema is often precipitated by or exacerbated by a change in climate. Heat and sweating can make eczema worse, and a cold, dry environment can also cause an exacerbation. Unless you suspect unusual infection, you will rarely go amiss with an initial two-week trial of a strong topical steroid – or topical steroid with antibiotic – to reduce any superimposed inflammation, helping guide any further investigation and management.
2 Insect bites can lead to nodular prurigo
Insect bites on exposed areas are common after travel to hot countries, but patients rarely remember being bitten unless they have had multiple bites. The pruritus caused by insect bites will frequently lead to scratching, which can result in the development of nodular prurigo. Treatment of nodular prurigo requires use of both emollients and potent topical steroids, sometimes under occlusion. Histology may be necessary for a single nodule, or for treatment-resistant cases.
3 Ecthyma can be travel-related
If a patient presents with nodules on the limbs after travel, it is important to include travel-related ecthyma in the differential diagnosis. Ecthyma may be due to infection with staphylococcus or streptococcus, or after travel may be due to more unusual bacteria. Travel-related ecthyma can occur after direct trauma or from contact with wild animals. If suppurating or ulcerative lesions do not respond to a two-week course of a penicillin or second-generation macrolide, consider referral.
4 Cutaneous larva migrans is a common global infestation
Cutaneous larva migrans is caused by canine hookworm larvae, for whom humans are accidental hosts.
This parasitic infection is widespread in the tropics and sub-tropics, and there is usually a history of walking barefoot on sand or soil.
The larvae cannot complete their life cycle or penetrate beyond the epidermis, and migrate slowly at a rate of 1-2cm per day.
This leaves an itchy, irregular red track with a typical clinical appearance.
Treatment is with albendazole 400-800mg (according to body weight) daily for three days, or ivermectin 200µg/kg stat dose. Avoid these drugs in pregnancy.
5 Always consider fungal infection
If the eruption has a well-demarcated border or pustular appearance, but is not responding to anti-inflammatory or anti-staphylococcal treatment, consider dermatophyte infection.
Consider deep fungal infection with unusual species in the traveller returning with slow-growing, progressive nodular lesions, particularly on the extremities.
Remember to take a good travel history, including exposure to bat or bird droppings, or exposure to spores in soil from tree planting.
6 Think of cutaneous leishmaniasis with slowly progressive lesions
Leishmaniasis is a parasitic infection transmitted via the bite of certain species of sand fly, which is now endemic in all countries bordering the Mediterranean.
It should be considered in any traveller returning from a country of endemicity who has unresolving skin lesions that slowly progress despite initial antimicrobial
The incubation period is typically a few weeks after the bite, with characteristic appearance initially as a papule, which slowly progresses to either dry or wet plaques with a raised, undermined edge.
Referral should be considered to the Hospital for Tropical Diseases in London.
7 Coral and marine life can cause a dermatitis, or atypical mycobacterial infection
Skin contact with coral or other sea life from swimming, snorkelling or diving can lead to a persistent dermatitis.
Seabather's eruption is a relatively common dermatitis, occurring within hours of the toxin's release from particular sea anemone larvae which can become trapped under bathing suits or wetsuits.
Jellyfish stings can cause a persistent contact dermatitis with recurrent eruptions for some months after exposure.
Skin abrasions from coral can cause a contact dermatitis, or a nodular eruption. Atypical mycobacterial infection must then be considered.
8 Consider empirical treatment if symptoms occur after a tick bite
Ticks can carry a variety of pathogens and can cause Lyme disease at temperate latitudes, or typhus or spotted fever at tropical latitudes.
The erythema migrans rash of Lyme disease is an expanding red annular plaque that can appear up to a month after an infectious bite.
Typhus or spotted fever can occur, typically from a tick bite on safari after visiting a game park. These cause a petechial rash, and if the patient is systemically unwell they may require admission.
Empirical treatment for all of these infections should begin as soon as the diagnosis is suspected, prior to serological confirmation. The drug of choice is doxycycline 100mg bd for two weeks.
9 Include in the history country of origin and immunosuppression
The history is vitally important in getting on the right diagnostic track. Cutaneous tuberculosis can have a number of presentations and may need to be suspected in travellers who arrive from high-prevalence areas – such as the Indian subcontinent.
HIV often presents with skin manifestations and needs to be considered with travel from sub-Saharan Africa.
A history of current immunosuppressive medication is also crucial in helping with the differential diagnosis, as this may increase the risk of both unusual infections and malignant skin lesions.
10 Inflammatory disorders can arise coincidentally after travel
Inflammatory disorders can also present after travel.
The dermatological presentation of sarcoidosis can be protean.
Systemic lupus erythematosus and subacute lupus can present with a photosensitive rash.
If the patient has not responded to initial treatment measures, and you don't want to miss an inflammatory aetiology, request blood tests for FBC, erythrocyte sedimentation rate, TFTs, antinuclear antibodies, antineutrophil cytoplasmic antibody and angiotensin-converting enzyme, and consider a chest X-ray.
Dr Sara Ritchie is a GP in Stoke Newington, north London, and clinical assistant in dermatology at University College London Hospital