Gnathostomiasis, another emerging imported disease

Abstract

Gnathostomiasis is a food-borne zoonosis caused by the late-third stage larvae of Gnathostoma spp. It is being seen with increasing frequency in countries where it is not endemic and should be regarded as another emerging imported disease. Previously, its foci of endemicity have been confined to Southeast Asia and Central and South America, but its geographical boundaries appear to be increasing, with recent reports of infection in tourists returning from southern Africa. It has a complex life cycle involving at least two intermediate hosts, with humans being accidental hosts in which the larvae cannot reach sexual maturity. The main risks for acquisition are consumption of raw or undercooked freshwater fish and geographical exposure. Infection results in initial nonspecific symptoms followed by cutaneous and/or visceral larva migrans, with the latter carrying high morbidity and mortality rates if there is central nervous system involvement. We review the literature and describe the epidemiology, life cycle, clinical features, diagnosis, treatment, and prevention of gnathostomiasis.

FIG. 1.

Map of countries with reported acquisition of gnathostomiasis.

FIG. 2.

Life cycle of Gnathostoma spinigerum. (Adapted from an image from the CDC-DPDx [www.dpd.cdc.gov/dpdx/HTML/gnathostomiasis.htm].)

FIG. 3.

Photograph of a third-stage larva of Gnathostoma spinigerum, showing the entire larva (A) and the head with hooks (B).

FIG. 4.

Photograph showing cutaneous larva migrans due to Gnathostoma spinigerum on the forehead (A) and shoulder (B). (Reprinted from reference .)

FIG. 5.

Magnetic resonance image of thigh with Gnathostoma sp. larva. (Reprinted from reference .)

FIG. 6.

(A) Hematoxylin- and eosin-stained cross-section of a Gnathostoma organism taken from a subcutaneous nodule above the right breast of a patient, showing the esophagus. Note the presence of cuticular spines (arrow). (B) Another hematoxylin- and eosin-stained cross-section of a Gnathostoma organism, taken from the same specimen as for panel A, showing the intestinal cells and characteristic large lateral chords (LC). (Panel A is from Diagnostix Pathology Laboratories LTD and the CDC-DPDx and panel B is from the CDC-DPDx [www.dpd.cdc.gov/dpdx/HTML/gnathostomiasis.htm].)