Download Gongylonema Infection of the Mouth in a Resident of Cambridge

BRIEF REPORT
Gongylonema Infection
of the Mouth in a Resident
of Cambridge, Massachusetts
Mary E. Wilson,1,2 Carol A. Lorente,3 Jennifer E. Allen,1,2
and Mark L. Eberhard4
1
Mt. Auburn Hospital, Cambridge, 2Harvard Medical School, Boston,
and 3Harvard Vanguard Medical Associates, Massachusetts General Hospital,
Harvard School of Dental Medicine, Boston, Massachusetts; and 4Division
of Parasitic Diseases, National Center for Infectious Diseases, Centers
for Disease Control and Prevention, Public Health Service, United States
Department of Health and Human Services, Atlanta
We report a case of Gongylonema infection of the mouth,
which caused a migrating, serpiginous tract in a resident of
Massachusetts. This foodborne infection, which is acquired
through accidental ingestion of an infected insect, such as a
beetle or a roach, represents the 11th such case reported in
the United States.
Several nematode parasites can migrate within the superficial
soft tissues after being ingested or after entering through the
skin. These migrations typically are restricted to the skin, as in
the case of cutaneous larva migrans that is caused by various
hookworm or Strongyloides species in animals, or they may
occur in the skin and other tissues, as in the case of Gnathostoma and zoonotic filarial infections. In humans, only 1 type
of nematode localizes primarily in the oral cavity: Gongylonema
species. Some 40–50 cases of gongylonemiasis in humans have
been reported, including cases from Europe, North Africa,
China, New Zealand, Sri Lanka, and the United States [1, 2].
We report the 11th case of gongylonemiasis that has occurred
in the United States, to alert physicians to the characteristic
clinical and parasitologic findings associated with such infection.
Case report. In September of 1999, a healthy, 38-year-old
schoolteacher sought medical evaluation for what she described
as the presence of a worm in her mouth. Approximately 6
months earlier, she had noted in her cheek an irregular area
that she could feel with her tongue. She thought that it was a
Received 19 June 2000; revised 21 September 2000; electronically published 9 April 2001.
Reprints or correspondence: Dr. Mark L. Eberhard, Division of Parasitic Diseases F13, CDC,
4770 Buford Hwy. NE, Atlanta, GA 30341-3724 ([email protected]).
Clinical Infectious Diseases 2001; 32:1378–80
2001 by the Infectious Diseases Society of America. All rights reserved.
1058-4838/2001/3209-0020$03.00
1378 • CID 2001:32 (1 May) • BRIEF REPORTS
patch of dry mucosa. Two days before she was seen, the patient
had noted that the patch was a mass that was migrating. She
had been able to see a serpiginous, transparent form that she
described as looking like a cellophane noodle. She estimated
that the rate of movement of this form was 2–3 cm per day.
She had no associated symptoms, and she denied having fever,
chills, nausea, vomiting, sore throat, or other skin lesions.
In April 1999, the patient had vacationed for a week in
Mexico near the Guatemalan border. During a day trip to the
mountains, she had gone swimming in a pond located adjacent
to waterfalls and had also eaten a local dish, which she thought
might have contained cabbage. She said that the food was raw,
crunchy, and saladlike. Approximately 12 h after eating this
food, she and 5 other individuals became ill with nausea, vomiting, and dizziness. The acute illness resolved without specific
treatment. The patient reported that she had frequently eaten
sushi in the United States, but she indicated that she had never
(intentionally) ingested beetles.
The patient had moved from France to the United States in
1981, but she returned to France at least once each year for
visits. She had spent 3 weeks in France in July 1999, after the
onset of symptoms. She had also visited Italy in 1995, but she
had never visited Asia or Africa. Her only trip to Latin America
was the aforementioned trip to Mexico.
The patient’s past medical history included appendectomy
and tonsillectomy. Her complete blood count was normal and
showed no increase in eosinophils.
Examination of the patient’s mouth revealed a superficial,
filamentous, submucosal mass (diameter, 0.2 mm) in a sinusoidal shape. The total size of the mass was ∼1.0 cm2. During
a period of 4 days, it migrated from the right side of the buccal
mucosa to the midline of the lower lip, and at one point it
migrated to a deeper position under the vermilion border of
the lip and was barely visible. It subsequently (within 24 h)
migrated to a more superficial position. With use of topical
anesthesia (20% benzocaine gel), the mandibular buccal mucosa was anesthetized, and a small spoon curette was placed
under the middle of the filament. The filament was gently teased
from the mucosa, removed intact, and placed in a 95% alcohol
solution. There was no local bleeding or discomfort.
Albendazole, 200 mg given twice daily, was prescribed for 3
days. After having taken 3 doses, the patient discontinued taking albendazole because of nausea. She noted no changes in
her mouth after the removal of the parasite.
Specimen.
A small, female nematode was received for
study; the specimen was intact and was ∼25 mm in length by
the feces of the aforementioned species and require ingestion
by an appropriate insect host, such as a cockroach or a dung
beetle. The parasite undergoes obligate development to the infective stage within the insect (20–30 days after ingestion), and
infection of the definitive vertebrate host occurs after ingestion
of the insect. Adult worms require some 60–80 days to develop
in the definitive host after ingestion of an infected insect.
In humans, ingestion is typically accidental and unrecognized. None of the data from recorded cases of G. pulchrum
infection have indicated that the infected patients had knowingly ingested insects. Although the life cycle of G. pulchrum
is well known, the factors that put some people at increased
risk for infection with G. pulchrum are not clearly understood.
It is plausible that the risk of eating insect-contaminated food
is increased in areas where levels of sanitation are poor, including some areas visited by travelers. In some parts of the
world and in some cultures, insects are an important source
of protein and calories, and gongylonemiasis could potentially
be a risk for those who eat uncooked insects. Presumably, a
roasted or otherwise well-cooked insect would pose no risk of
Gongylonema infection.
Entomophagy (eating insects) has been practiced throughout
Figure 1. Photomicrograph of anterior end of worm illustrating the
bosses (arrows) characteristic of organisms of the genus Gongylonema.
Scale bar, 50 mm.
0.2 mm in maximum diameter at midbody. The anterior end
of the worm was slender and threadlike, and it had a maximum
diameter of only 0.05 mm, whereas the posterior end of the
worm was stout and did not taper appreciably. The most anterior 0.8 mm of the worm (figure 1) bore bosses (scutes) that
were typical of organisms of the genus Gongylonema. Beginning
just posterior to the bosses on the anterior end, the cuticle bore
prominent transverse striations (figure 2). These striations continued to the tail, but they diminished in prominence near the
posterior end of the worm.
The esophagus was long (length, 5 mm). The ovejector was
prominent and was located 1.7 mm anterior to the tail. The
tail was conically tapered and was 0.2 mm in length. The worm
was gravid, and fully embryonated eggs were present in the
uteri (figure 2).
Discussion. Gongylonema pulchrum is the species that has
been identified as the cause of Gongylonema infection in humans [1, 2]. Infection caused by this species has been reported
to occur in sheep, cattle, pigs, and other ungulates, and in bears
and monkeys. The life cycle of G. pulchrum requires an insect
as the intermediate host. Fully embryonated eggs are passed in
Figure 2. Photomicrograph of a worm at midbody illustrating the
embryonated eggs in utero. The transverse striations of the cuticle are
visible but out of focus. Scale bar, 25 mm.
BRIEF REPORTS • CID 2001:32 (1 May) • 1379
history, and it remains common today in some parts of the
world [3, 4]. Even though they may not know it, humans
regularly eat insects and insect parts, and the US Food and
Drug Administration has developed guidelines for the allowable
number of insect eggs, immature and adult insects, and insect
parts that can be present in various foods (e.g., up to 30 insect
fragments per 100 g of peanut butter; 475 insect fragments per
50 g of ground pepper; and 35 fruit fly eggs and 10 whole or
equivalent insects in every cup of golden raisins) [5].
Because of the cosmopolitan distribution of Gongylonema
species, travel to an exotic location is not necessary for infection
to occur. The woman who we describe may have ingested the
parasite along with insect parts consumed in Mexico 5 months
before the parasite was identified, but she just as well could
have acquired the infection in the Cambridge, Massachusetts
area. Although there is scant published literature on this topic,
reported experience would suggest that infection may persist
for many months but that it ultimately is self-limiting. The
parasite can be removed without the use of complicated invasive
procedures, and serious complications of infection have not
been reported.
Of the 11 reported cases from the United States, the majority
have been reported among persons living in the southeastern
states, although the last 2 cases have been from large cities in
the Northeast. The infections have been reported in adults,
men and women have seemed to be equally affected, and the
clinical presentation has been relatively uniform. Patients frequently have described the sensation of an object moving in
the mouth, and as often as not, they have removed the worms
themselves.
For urban residents, infection with G. pulchrum should be
an unusual occurrence, given the nature of the usual hosts. On
the other hand, infection with Gongylonema neoplasticum,
which is a natural and common parasite among rats, would
seem to be a much more likely cause of human infection because of the ubiquitous distribution of rats. The specimen from
the present case, and the specimen from the most recent previous report of Gongylonema infection in a resident of New
York City [6] were compared with G. neoplasticum material
(which included 2 lots of worms collected from rats in New
Orleans [kindly provided by Dr. M. D. Little]). Clearly distinct
morphological differences, especially with regard to the shape
of the female tail, were evident in a comparison of the specimens obtained from humans and the G. neoplasticum material.
1380 • CID 2001:32 (1 May) • BRIEF REPORTS
Although worms collected from humans usually have been
smaller than the average size range reported for G. pulchrum,
a wide range in size has been noted for that species, depending
on the host from which the worms were recovered [7]. Because
of an absence of male worms in most cases, it has not been
possible to definitively identify the species, but it most likely
is G. pulchrum.
Treatment with albendazole, a broad-spectrum anthelmintic,
was initiated because of the concern that additional worms
might still be present. There is no confirmed proof that treatment with albendazole or any other anthelmintic results in a
cure in humans. However, because of the wide margin of safety
associated with this drug and the possibility of additional
worms being present, treatment seems to provide some advantages over no treatment. Treatment done by removal of
worms either by use of the fingers or by use of a curette in a
physician’s office can also be successful.
Clinicians, other health care providers, and microbiologists
alike need to be alert to the possibility of infection with Gongylonema species. The characteristic clinical finding of a wormlike object migrating in the mouth area, including the buccal
mucosa, gums, lips, or palate, should be a clear signal for consideration of Gongylonema infection in the differential diagnosis.
References
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