Eosinophilia with pruritus

General

There is sometimes an incidental combination of eosinophilia and pruritus (no causal relation). In a traveller to the (sub)tropics, it occasionally concerns a cosmopolitan disease, though there is often an exotic cause. Scabies (Sarcoptes sp.) and pubic lice (Phthirus pubis) are a frequent cause of pruritus, but do not so frequently cause eosinophilia.

Reactions to bites and stings

Reactions to insect bites and stings (Culicoides sp, bedbugs, etc.), trombiculosis (harvest mites), contact dermatitis (e.g. to plants) and allergic reactions to medications taken during a trip sometimes raise diagnostic problems. Itching dermatitis can be elicited by the hairs of caterpillars of certain Lepidoptera. The hairs of certain bird spiders can also cause prolonged, severe pruritus.

Worm infestations

Worm infestations must be considered. Certain infections are obvious at a glance (e.g. typical larva currens, larva cutanea migrans). Other diseases are much more difficult to identify (e.g. gnathostomiasis). It should be borne in mind that a positive parasitological result may confirm the diagnosis, but that a negative result is less conclusive. In filarioses one is often confronted with the difficulty of amicrofilaraemic infections. This latter problem frequently occurs with Loa loa infections. Calabar swellings and subconjunctival migration of the adult worm will suggest the diagnosis in these cases. Note that Onchocerca volvulus microfilariae are only found in dermal fluid (not in blood). Serological tests have only a limited sensitivity and specificity. Ectopic localisations of worms can cause various cutaneous symptoms (e.g. Poikilorchis infestations, sparganosis). Cercarial dermatitis can occur after skin contact with contaminated fresh water. Early after infestation no Schistosoma ova will yet be detectable. If the infection is casued by a parasite species which has an animal (e.g. birds) as its normal host, the cercarial dermatitis will be more pronounced, but no patent infection will ensue. One of the frequent causes of urticaria in travellers is anisakiasis. This condition is frequently misdiagnosed as allergy to fish.

Itching after swimming in seawater

A planula larva dermatitis will occur shortly after bathing in seawater in which these microscopic animals (coelenterata) are present in large numbers. Fire coral dermatitis can cause quite annoying discomfort (irritation due to nematocysts). Contact with jellyfish can cause linear skin lesions. Traditional aquagenic urticaria is not related to travel.

Category: Medicine Notes