Atypical gnathostomiasis-confirmed cutaneous larva migrans, Vietnam
- 1 School of Population Health, University of New South Wales Faculty of Medicine, Sydney, New South Wales, Australia
- 2 Department of Infectious Diseases, MEDIC Medical Center, Ho Chi Minh City, Viet Nam
- 3 Viet-Anh Department, Cho Quan Hospital, Ho Chi Minh, Viet Nam
- 4 Therapeutic and Research Department, Institute of Malariology, Parasitology, and Entomology Quy Nhon, Quy Nhon, Viet Nam
- Correspondence to Dr Cuong Minh Duong; minh.duong@unsw.edu.au
Abstract
We reported a case of gnathostomiasis in a 42-year-old woman with an unclear history of eating high-risk foods and had a non-migratory skin lesion, negative serological testing and normal blood eosinophil counts. A diagnosis of gnathostomiasis was based on a live, third-stage Gnathostoma spinigerum larva that was randomly taken from the patient’s skin lesion by herself. The presenting case report demonstrates challenges in correctly diagnose cutaneous gnathostomiasis even in endemic countries due to atypical skin lesions, negative serology testing and the absence of eosinophilia and thus, the widely used classic triad of suggestive evidence of gnathostomiasis is not fulfilled.
Background
Gnathostomiasis is caused by the migration of the third larval stage of nematodes of the Gnathostoma spp. through human tissues.1 Although the disease is endemic in Southeast Asia, Japan and Latin America, it has been increasingly reported in non-endemic countries as an emerging imported disease.1 2 In countries where Gnathostoma is not endemic, correctly diagnosing the disease is a challenge as few clinicians are familiar with this condition.3 Therefore, diagnosis is often missed or prolonged, with potentially serious consequences.2 In Vietnam, infections with all four species including G. spinigerum, G. hispidum, G. doloresi and G. vietnamicum have been found in animals.4 However, human gnathostomiasis is still a rare disease and only G. spinigerum has been identified to cause human cases.4 The first case was reported in 1965.5 No further case was documented until 1998 when three cases with cutaneous larva migrans (CLM) were reported, followed by one reported case in 2020.6 7 The clinical presentations include cutaneous form and visceral form.2 Since isolating larvae from the lesions is often difficult, a classic triad of eosinophilia, migratory lesions, and obvious exposure risks suggesting gnathostomiasis is widely used in the clinical setting.2 Exposure risks include residence in or travel to an endemic area and eating contaminated food such as raw or undercooked fish, eels, frogs and chickens.2 8 9 We presented a case with cutaneous gnathostomiasis who did not meet any criterion of the classic triad of suggestive evidence of gnathostomiasis. We also highlighted the challenge in correctly diagnosing this disease in the clinical setting by discussing the reliability of the classic triad of suggestive evidence of cutaneous gnathostomiasis.
Case presentation
A 42-year-old female farmer presented with a problem of having a bug under her skin. Two weeks before admission, she developed body itching with raised, red lines when scratching, but they disappeared afterwards. A red, painful, ill-defined, non-movable nodule appeared in the right upper quadrant (RUQ) on day seventh. Despite using paracetamol and antihistamine, her condition remained unchanged. On day 14th at 07:00, she felt something moving under her skin at the nodule. She accessed to the inside of the nodule and picked up a live, dull-white, mosquito larva sized worm. The worm was placed into a container and was brought to our clinic at around 16:00 the same day. She did not have any history of liver abscess and parasitic infection as well as similar symptoms. The patient never contacts livestock and wild animals. She always uses personal protective equipment including long rubber gloves and boots, face mask and waterproof hat when doing farming to minimise her exposure to soil, chemicals and sunlight. She never walked barefoot but could not remember if she ate inadequately cooked freshwater fish, and frogs.
Investigations
She was well and did not have fever, cough, abdominal pain, abnormal bowel habit, headache, nausea and blurred vision. Physical examination found no nodule, but a small, non-specific rash in the RUQ (figure 1). She was asked to undertake a complete blood count, aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyltransferase (GGT), ELISA to detect IgG against Toxocara spp., Cysticercose, Fasciola sp., and Strongyloides stercoralis, and Gnathostoma spp., and abdominal ultrasonography (table 1). Microscopy of the detected worm was also ordered.
Laboratory and imaging test results
| Laboratory and imaging tests | Results |
| Leucocyte counts | 7490/mm3 (reference range 4000–10 000/mm3) |
| Absolute eosinophil counts | 60/mm3 (reference range 0–500/mm3) |
| AST | 22.07 U/L (reference range <35 U/L) |
| ALT | 17.17 U/L (reference range <30 U/L) |
| GGT | 10.23 U/L (reference range <36 U/L) |
| ELISA detecting IgG against Toxocara spp. | Negative |
| ELISA detecting IgG against Gnathostoma spp. | Negative |
| ELISA detecting IgG against Cysticercose | Negative |
| ELISA detecting IgG against Fasciola sp. | Negative |
| ELISA detecting IgG against Strongyloides stercoralis | Negative |
| Abdominal ultrasonography | Normal hepatobiliary system |
Skin lesion in the patient’s right upper quadrant at the time of hospital admission. Note: an arrow indicates the area of skin lesion.
Differential diagnosis
Potential diagnoses included gnathostomiasis, CLM, toxocariasis, cutaneous fascioliasis and larva currens (Strongyloides). CLM is caused by the migrating Ancylostoma ceylanicum larvae in the skin.10 CLM rashes are an erythematous, serpiginous, pruritic, cutaneous eruption and usually in the feet and associated with walking barefoot. However, a case of CLM was reported with a typical serpiginous skin lesion that was observed at the submammary region.11 Despite the atypical location of the lesion, this case was correctly diagnosed based on the typical CLM skin lesion.11 Although the lesion location of our patient is similar to that of this case, the lesion pattern of our patient is not clinically compatible with CLM. Moreover, our patient never walked barefoot making a diagnosis of CLM less likely. Cutaneous lesions may be caused by a transdermal migration of Strongyloides larvae, in which the rashes are usually linear and recurrent with an intervening symptoms-free period.10 Since this manifestation was not present in our patient, larva currens was excluded. Cutaneous manifestations of human toxocariasis include generalised chronic pruritus associated with nodular prurigo, chronic urticaria and eczema.12 Given her generalised itching, toxocariasis could not be excluded. However, her painful nodule made this diagnosis less likely. Patients with cutaneous fascioliasis usually have a history of liver abscess, followed by a painful swelling surrounded by a serpentine red coloured vesicular lesion in the RUQ.13 Our patient’s clinical symptoms and lack of history of liver abscess made this diagnosis less likely. Cutaneous gnathostomiasis usually causes nodular migratory panniculitis located at the trunk.1 These lesions are ill-defined and pruritic, painful, or erythematous.1 Our patient’ painful, ill-defined nodule located at the trunk suggested cutaneous gnathostomiasis. The removal of the worm may explain the disappearance of the nodule on admission. Microscopy found a live, third-stage larva of Gnathostoma spinigerum confirming cutaneous gnathostomiasis (video 1).
Treatment
Complete removal of the worm is the best treatment for cutaneous gnathostomiasis.1 14 Since the worm had been removed and the patient refused to undertake oral anthelmintics, no further specific treatment was provided.
Outcome and follow-up
To prevent relapse as suggested elsewhere,7 our patient was followed up at 2 weeks after admission and every 3 months until 1 year and showed no relapse.
Discussion
Diagnosing the causative agent based on the clinical symptom is not practical because different helminth species can cause overlapping cutaneous manifestations, especially if patients live in or travel to endemic countries of several helminth species such as Vietnam and other countries in South East Asia.10 It is widely agreed that a triad of eosinophilia, migratory skin lesions and exposure risk suggests gnathostomiasis.1 However, our patient had negative serological testing, normal blood eosinophil counts and an unclear history of eating high-risk foods. Regarding the skin lesions, it is suggested that cutaneous gnathostomiasis should be suspected in patients with creeping eruption, migratory swellings, a skin abscess or nodules.14 This is because the third-stage larva of Gnathostoma spinigerum can survive in the human body for more than 10 years if left untreated.14 During this period, symptoms may recur intermittently with brief and less intense episodes of swelling.14 Our patient did not have any history of parasitic infection as well as similar symptoms. However, although the symptoms of our patient were not clinically compatible with cutaneous gnathostomiasis, a non-movable nodule may suggest this disease provided that Vietnam is an endemic area of Gnathostoma spinigerum. The strongest evidence supporting a diagnosis of gnathostomiasis in our patient was the microscopy results. Indeed, given eosinophilia is documented in only 50%–70% of infected cases, normal eosinophil counts do not exclude the diagnosis.1 ELISA for L3 IgG antibody has a low sensitivity, which means false-negative results are highly likely.1 Therefore, western blot assays directed against a crude preparation of G. spinigerum are recommended.1 However, this test is not available in Vietnam.1 It should be noted that in case of atypical localisation of skin lesions like the reported CLM,11 the differential diagnosis with gnathostomiasis may be a challenge. Thus, the microscopic examination of the worm taken from the skin lesion like what we did for our patient is essential in such cases. Alternatively, a western blot analysis should be used, when available.1 It is documented that in cutaneous gnathostomiasis, the induction of the parasite migration towards the surface of the lesion usually takes place one to 5 days after using anthelmintic.1 Although our patient did not receive specific treatment, the worm migrated to the surface of the lesion and was detected randomly. Although removal of larvae is considered the most effective treatment for cutaneous gnathostomiasis,14 empirical treatment with oral anthelmintics may be considered in this case because latent larvae can be present and cause relapse. However, our patient refused to undertake oral anthelmintics because she was concerned about the side effects of these medications. Indeed, oral albendazole and oral ivermectin which are used to treat this disease can cause several side effects such as nausea, diarrhoea and allergic reactions, even when administrated for a short period of time.11 14 Considering her reference and health condition as well as the fact that the worm was removed, she was asked to undertake a long-term follow-up plan which found no relapse after 12 months. The follow-up is still ongoing.
The presenting case report demonstrates challenges in correctly diagnosing cutaneous gnathostomiasis even in endemic countries due to untypical skin lesions, negative serology testing and the absence of eosinophilia. Gnathostomiasis needs to be considered in patients with any suggestive symptoms, especially those coming from or travel to endemic areas although they may not fulfil the classic triad of suggestive evidence of gnathostomiasis.
Patient’s perspective
I was born and grew up in the countryside. I am now living there and working as a farmer. I had not heard about gnathostomiasis until the doctor told me that I had this disease. I do not know how to explain my feeling when I picked up a live worn from my body. It was very scary and disgusting. I believed that I need to bring this worn to the clinic so that the doctor can see it and treat my disease more easily. That was why I brough it to the clinic. The doctor explained to me that Vietnam is an endemic area of this disease. This means that we can acquire this infection if we eat raw or inadequately cooked freshwater fish, eels, frogs, and chickens. I never eat inadequately cooked eels, and chickens, but I am not so sure if I ate inadequately cooked freshwater fish, and frogs. Barbecued freshwater fish or frogs are among the most common foods in my homeland. The doctor said that the worm had been completely removed from my body. I had also been followed up for a while and there was no relapse. This means that I am free from the disease although I still need to undertake a periodic follow-up. I talked my myself that I will not eat anything that is inadequately cooked and will let all my family members and neighbours know about this disease and preventive measures.
Learning points
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Patients with cutaneous gnathostomiasis may present with atypical skin lesions, negative serology testing and the absence of eosinophilia making the diagnosis of this infection difficult.
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Cutaneous gnathostomiasis needs to be considered in patients coming from endemic areas although they do not fulfil the classic triad of suggestive evidence of gnathostomiasis.
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An unclear or a lack of epidemiological history of eating high-risk food does not rule out gnathostomiasis as long as the patients live in or travelled to endemic countries.
Ethics statements
Ethics approval
This case report has been approved by MEDIC Medical Center (reference number: 32/2020/NCKH-YTHH).
Footnotes
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Contributors Conception and design: all authors. Acquisition of data or analysis and interpretation of data: all authors. Drafting the article: CMD, PVDL. Revising the article critically for important intellectual content: all authors. Final approval of the version published: all authors. Agreement to be accountable for the article and to ensure that all questions regarding the accuracy or integrity of the article are investigated and resolved: all authors.
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Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
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Competing interests None declared.
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Provenance and peer review Not commissioned; externally peer reviewed.
- © BMJ Publishing Group Limited 2021. No commercial re-use. See rights and permissions. Published by BMJ.
References
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