Parasitic Infections
Protozoal and helminth infections acquired in endemic regions or through food/water/vector exposure. UK clinicians encounter imported malaria, intestinal helminths, schistosomiasis, and toxocariasis among travellers and migrants; diagnosis requires geography, eosinophil count, and targeted tests.
Key Facts
Key points
- Malaria (falciparum): artesunate IV first line for severe (specialist); uncomplicated oral artemether/lumefantrine (Riamet) per weight-based dosing.
- Threadworm: mebendazole 100 mg single dose; repeat in 2 weeks; treat household.
- Hydatid disease: albendazole 400 mg BD** for months ± surgery — specialist.
- Schistosomiasis: praziquantel 40 mg/kg** single dose or divided (acute/schistosomal policies vary).
- Strongyloides: ivermectin 200 mcg/kg** for 2 days; albendazole alternative — treat before immunosuppression if possible.
Overview
Approach
Take a travel/food/water exposure history; eosinophilia suggests helminth or certain protozoa.
Protozoa vs helminths
Different diagnostics (stool O&P, serology, PCR) and treatments.
Clinical Presentation
Examples
Intermittent fever (malaria), GI symptoms, rash (acute schistosomiasis), Loeffler syndrome (migrating larvae).
Differential Diagnosis
| Presentation | Consider |
|---|---|
| Eosinophilia | Helminths, allergy, adrenal |
| Fever returned traveller | Malaria, typhoid, dengue |
Diagnosis / Investigation
Tests
Thick/thin films (malaria), stool PCR/O&P, serology (strongyloides, filariasis), eosinophil count.
Management
Principles
- Treat specific parasite; address dehydration and anaemia.
- G6PD screen before primaquine for malaria hypnozoites (vivax/ovale).
Prevention
Travellers' health advice, malaria chemoprophylaxis where indicated (e.g. atovaquone/proguanil).
Prognosis
Varies widely; delayed malaria treatment increases mortality; most intestinal helminths respond well.
Other Relevant Information
Neglected tropical diseases
Many require specialist tropical medicine input.