Parasitic diseases in travelers: a focus on therapy

Abstract

Parasitic infections are an important cause of illness among returned travelers, and can lead to considerable morbidity and, in some cases, mortality. The complexity of parasitic life cycles and geographic specificities can present diagnostic challenges, particularly in non-endemic settings to which most travelers return for care. Clinical manifestations reflect the diverse taxonomy and pathogenesis of parasites, and appropriate diagnosis and management therefore necessitate a high index of suspicion of parasitic illnesses. Much of our knowledge surrounding management of parasitic infections in travelers is extrapolated from evidence derived in endemic populations, or is based on expert opinion and case series. We herein provide an overview of parasitic diseases of short-term travelers, and summarize current therapeutic strategies for each illness.

Keywords::

• diarrhea
• eosinophilia
• fever
• helminthes
• parasites
• pharmacology
• protozoa
• rash
• skin lesions
• travel

Financial & competing interests disclosure

K Kain is supported by a Canada Research Chair in molecular parasitology and by Canadian Institutes of Health Research MOP 13721. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.

Key issues

• Collectively, parasitic infections are relatively common in travelers, occurring in up to one-third of patients who present for medical care post-travel.

• Malaria, cutaneous larva migrans and intestinal protozoa are the most common parasitic diseases of short-term travelers to the developing world.

• Parasitic infections are important to diagnose and treat in returned travelers as they can contribute to significant short- and long-term morbidity and in some cases can be rapidly fatal without prompt treatment.

• Parasitic infections can present in a myriad of ways, though fever, eosinophilia, diarrhea and skin rash are the most common syndromic presentations of parasites in travelers.

• Appropriate diagnosis and management of parasitic infections require knowledge of the epidemiology, geography, pathogenesis and lifecycle stages of parasites that can be acquired by travelers.

• Knowledge of geographical distribution and pharmacoepidemiology is particularly relevant for management of parasitic infections such as malaria, leishmaniasis and giardiasis, where drug resistance can result in clinical failures.

• Rare or complicated cases of parasitic infections in travelers should be referred to specialized tropical medicine centers for management.

• Empirical evidence to support current management practices for parasitic infections in travelers is generally sparse, and much of the evidence surrounding pharmacotherapy is expert opinion or case series level or extrapolated from trials conducted in endemic settings.

• There is a dire need for improved surveillance of parasitic diseases in travelers and for additional evidence to support management practices in this unique population.

• While these infections cause significant morbidity in returned travelers, most of these parasitic infections do not pose a risk to family and close contacts; most cannot be transmitted from person to person through ordinary interactions.

Notes

ⁱUSA: Contact the CDC malaria hotline at [phone] during business hours or [phone] on evenings and weekends. Canada: Contact a regional Canadian Malaria Network affiliated pharmacy listed at www.phac-aspc.gc.ca/tmp-pmv/quinine/index-eng.php

ⁱⁱThe WHO-IWGE standardized classification for cystic echinococcus (CE) describes six cyst stages based on abdominal ultrasound features. CE1 and CE2 represent active cysts, CE3 cysts are transitional, CE4 and CE5 are inactive and CL stage cysts are undifferentiated without a definite parasitic etiology [93].