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Our lot is a perilous age … but where shall we fly to escape from pestilences that come and pestilences that do not come, from ships that bring us yellow fever, from cattle diseases that can only be exterminated by exterminating the cattle, from infectious patients whose pulses must be felt with a pair of tongs and their chests explored with tarred stethoscopes.
JACOB BIGELOW 1860
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Doctors in western countries—including Australia, with its own tropical diseases in the far north—are more likely to encounter tropical diseases in the traveller returning from countries where these disorders are endemic. Many of these diseases are likely to be encountered in newly arrived refugees (see CHAPTER 135). The diseases include bacterial infections such as tuberculosis (a huge problem), plague, melioidosis, leprosy, typhoid/cholera, zoonoses. Other infections to be considered are parasitic, Rickettsia and myriad viral infections including haemorrhagic fevers, various types of encephalitis, yellow fever, polio, trachoma, hepatitis, lyssavirus such as rabies and bat bite infections, dengue and influenzas.
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It is worth reviewing the various protozoal and helminthic parasitic infections that need to be considered in the sick returned traveller.1 The helminths (worms) include cestodes (tapeworms), trematodes (flukes) and nematodes (roundworms).
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Protozoal infections: African trypanosomiasis (sleeping sickness), American trypanosomiasis (Chagas disease), amoebiasis, babesiosis, coccidiosis and microsporodiosis, cryptosporidiosis, giardiasis, leishmaniasis—cutaneous and visceral (kala-azar), malaria, toxoplasmosis, trichomonas
Cestodes (tapeworms): Cysticercosis (Taenia solium, T. saginata), echinococcus (hydatid disease)
Trematodes (flukes): Schistomiasis (bilharziasis), clonorchiasis, paragonimiasis
Nematodes (roundworms): Ascariasis, enterobiasis (pinworm), Dracunculus medinensis (Guinea worm), filariasis, hookworm, larva migrans (cutaneous and visceral), strongyloidiasis, trichinosis (Trichinella spiralis), trichuriasis (whipworm)
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PROBLEMS IN THE RETURNED TROPICAL TRAVELLER
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Most will present within 2 weeks except HIV seroconversion infection.
Common infections encountered are dengue fever, giardiasis, hepatitis A and B, gonorrhoea or Chlamydia trachomatis, malaria and helminthic infestations.
An important non-infection problem requiring vigilance is deep venous thrombosis (DVT) and thromboembolism.
The asymptomatic traveller may present for advice about exposure (without illness) or about an illness acquired such as rabies, malaria, schistosomiasis and STIs.
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Red flags in the returned traveller
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Gastrointestinal symptoms
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Stool microscopy and culture
Look for and treat associated helminthic infestation (e.g. roundworms, hookworms)
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Moderate or prolonged (>3 weeks) diarrhoea
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Usually due to Giardia lamblia, Entamoeba histolytica, Campylobacter jejuni (especially South-East Asia), Salmonella, Yersinia entero-colitica or Cryptosporidium.2
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Stool examination (three fresh specimens):
– microscopy
– wet preparation
– culture
Faecal Multiplex PCR (if available)
Treat pathogen (see guidelines under diarrhoea in CHAPTERS 14 and 44)
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Non-pathogens such as Escherichia coli and Endolimax nana are often reported but do not treat specifically.
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Note: Consider exotic causes ...