Furuncular cutaneous myiasis after travel in South America: case report and epidemiologic, diagnostic and management considerations

Abstract

Background

Dermatologic conditions are among the most frequent health problems in international travelers, following gastrointestinal and febrile illnesses. Myiasis, defined as infestation of human tissue by dipterous fly larvae, represents a noteworthy dermatologic diagnosis, particularly in travelers returning from tropical regions. Furuncular myiasis is the most recognizable form, presenting with painful nodules containing larvae, and is commonly caused by Dermatobia hominis in Central and South America. Increasing international travel is expected to raise the incidence of such conditions in non-endemic regions.

Case report and discussions

We report the case of a 77-year-old Romanian male, with co-morbidities, who developed cutaneous furuncular myiasis following a 12-day trip to Brazil and Argentina. The patient presented with painful nodular skin lesions on the upper limb approximately one month after returning. Initial treatments with anti-inflammatory agents and antibiotics were ineffective. Subsequent surgical drainage revealed the presence of larvae, confirming the diagnosis. Complete healing occurred within 2–3 weeks. Based on clinical presentation and travel history, Dermatobia hominis was considered the most probable etiologic agent, although molecular confirmation was unavailable. Discussion highlights the epidemiology and classification of myiasis-producing flies, emphasizing the geographic distribution of Dermatobia hominis and Cochliomyia hominivorax. Furuncular myiasis is often misdiagnosed as cellulitis or abscess due to nonspecific symptoms. Key diagnostic clues include persistent nodules with central punctum, serous discharge, and recent travel to endemic areas. Ultrasound can aid in identifying larvae, while laboratory confirmation enhances epidemiological surveillance. Management typically involves mechanical or surgical larval extraction, wound care, and monitoring for secondary infection. Preventive measures include insect repellents, protective clothing, and use of insecticide-treated nets. This case underscores the need for heightened clinical awareness in non-endemic countries, where travel-related parasitic infections are increasingly encountered. Pre-travel medical consultations are crucial for providing vaccinations, preventive advice, and education on insect protection. While our patient experienced a favorable outcome, delayed diagnosis and lack of preventive measures may increase morbidity.

Conclusion

With the rising popularity of travel to tropical areas, clinicians should consider cutaneous myiasis in travelers with persistent nodular skin lesions. Prompt recognition and extraction of larvae remain the cornerstone of effective treatment.

Background

Data from the GeoSentinel Surveillance Network indicate that dermatologic conditions are the third most common health issue among international travelers seeking post-travel medical care, following gastrointestinal and febrile illnesses, with 8–34% of international travelers experiencing dermatological issues during or after their trip [1]. A comprehensive analysis of over 4,700 returned travelers revealed that approximately 18% had a skin-related diagnosis and myiasis represented 2.7% of all dermatologic diagnosis, most of them acquired in Belize, Bolivia and Costa Rica [2]. Other authors reported myiasis in 3.5–9.3% of dermatological conditions in travelers returning from the tropics [3]. Myiasis is defined as the infestation of human or animal tissue by dipterous fly larvae. Several Diptera families might be responsible for human myiasis. The classification of myiasis is based on the affected area, leading to categories such as cutaneous, urogenital, and pulmonary myiasis [4]. Furuncular myiasis, one of its most recognizable forms, typically presents with painful nodules containing developing larvae [5]. Furuncular myiasis is most frequently caused by Dermatobia hominis in Central and South America, Cordylobia anthropophaga in sub-Saharan Africa, and Wohlfahrtia spp. in Eastern Europe, the Middle East, and parts of Asia. The distribution of causative dipterous species varies geographically, reflecting differences in fly ecology and host interactions [6, 7]. The rises in international travel could be associated with an expected increase in cases of myiasis and other travel-related diseases. We report the case of cutaneous myiasis in a Romanian traveler to South America and discuss the species biology in this region, as well as medical implications in order to raise awareness about this condition in the medical community and to educate travelers regarding the potential risks and the methods to prevent them.

Case report

A 77-year-old Romanian male, with a medical history of obesity, hypertension, dyslipidemia, atrial fibrillation, gonarthrosis, and prior myocardial infarction with angioplasty, presented with painful skin lesions on his left upper limb. The patient had recently returned from a 12-day trip (February 16–27, 2025) to Brazil and Argentina, where he visited rural regions, the Pampas, favelas, the Iguazu Falls, agricultural zones, and open-air markets. He had no prior travel medicine consultation and was unaware of repellent use. He denied any history of pre-existing lesions on the affected limb.

Approximately one month after returning, he presented to a dermatologist with two painful nodular lesions on the left upper limb, measuring 0.5–1 cm each, erythematous and covered by a hematic crust. He reported a localized sensation of electric current around the lesions. There was no fever or systemic involvement. He received local anti-inflammatory treatment, but showed no improvement. A month later, the nodules became larger (2–3 cm), indurated, with serosanguinous secretion and hematic crust (Fig. 1).

Fig. 1.

Clinical presentation of the furuncular lesion on the left upper limb (surgical stage)

He presented to the emergency surgical department, where incision and drainage were proposed. However, he refused the procedure and hospitalization at that time and was prescribed a 5-day course of amoxicillin-clavulanate. He returned after five days due to escalating pain. Surgical drainage revealed a larva and a second larva was extracted 48 h later from the adjacent lesion. He was then referred to an infectious disease specialist where furuncular myiasis was diagnosed based on the clinical presentation and the presence of larvae.

The extracted sample was sent to the parasitology laboratory. Using a stereomicroscope, the extracted sample was identified as a larval fragment. The white - coloured fragment presented rings of backward-pointing spines, encircling each body segment and mouth hooks at the anterior end (Fig. 2). The posterior end with the spiracles was missing. In this case, species-level identification was not performed. Definitive species confirmation would have required extraction of the entire larva for microscopic identification or molecular techniques which were not available. However, given the patient’s travel itinerary and clinical presentation, Dermatobia hominis was be considered the most probable etiologic agent. Healing was complete within 2–3 weeks.

Fig. 2.

Fragment of extracted larva, stereomicroscope 10x magnification

Discussion

The case presented here involved a traveler returning from South America, where Dermatobia hominis would typically be the expected agent for a nodular lesion [3–6, 8]. To date, over 20 fly species have been identified with biophagic larvae capable of causing myiasis in both humans and animals. In the Americas (New World), two notable species—Cochliomyia hominivorax (New World screwworm fly) and Dermatobia hominis (botfly)—are particularly widespread in tropical and subtropical regions [9]. The Old World species are often Cordylobia anthropophaga (furuncular) and Chrysomya bezziana (wound). Hypoderma spp. (warble flies) occur in both but primarily in livestock and Oestrus ovis (sheep nasal botfly) is classically Old World but now widespread [10].

Myiasis-producing fly species are classified based on their relationship with the host into the following categories: (a) Obligate myiasis producers: these parasites require a host to complete their life cycle and typically infest only living organisms. Examples include Cochliomyia hominivorax, Dermatobia hominis, and Gasterophilus intestinalis. (b) Facultative myiasis producers: these parasites are usually free-living flies that may opportunistically feed on decomposing organic matter or necrotic tissue, such as Sarcophaga species. (c) Accidental or false myiasis producers: these cases occur when free-living larvae are unintentionally ingested or inhaled [9]. Cochliomyia hominivorax and Dermatobia hominis differ in their patterns of infestation. Cochliomyia hominivorax typically affects open wounds or natural body openings (e.g., mouth, nose, ears), whereas Dermatobia hominis is primarily responsible for furuncular myiasis [11]. Dermatobia hominis is a member of the Diptera order commonly referred to as “myiasis-causing flies,” and is distinguished by the ability of its larvae to develop within the flesh of animals. Beyond its medical and economic significance, this botfly attracts scientific interest due to its unique biological features, particularly its reliance on aphoretic diptera to complete its life cycle. The larvae invade the host’s skin, leading to boil-like lesions that are itchy, painful, and resemble subcutaneous lumps, ultimately resulting in permanent skin damage.

Although Dermatobia hominis is distributed from Mexico to Argentina, there are data showing that the countries with the highest infection rates in travelers are Belize, Bolivia, and Brazil [12]. A retrospective observational study of patients who presenting with myiasis conducted between 1999 and July 2014 in the post-travel clinics in Israel found that among 90 patients diagnosed with myiasis, 72 (80%) acquired myiasis in Latin America in the Madidi National Park, Amazonas Basin, Bolivia [13].

Cutaneous myiasis is increasingly prevalent in Central and South America, even in urban areas with inadequate sanitary conditions. The spontaneous resolution of these conditions leads to a lack of seeking medical attention, and the countries with the highest number of reports do not necessarily reflect the geographic distribution of the continent. Cochliomyia hominivorax, historically endemic to Panama and other parts of the South American tropics with the Darién Gap acting as a containment barrier for Central and North America, has reemerged since 2023 with thousands of infestations reported in livestock in Panama and neighbouring countries, extending into Mexico during 2024–2025 and posing an increasing risk of incursion into the United States [14].

According to Robbins & Khachemoune, cutaneous myiasis may be divided into three main clinical forms, based on clinical presentation (Table 1) [8].

Table 1.

Clinical classification of cutaneous myiasis

Clinical form	Clinical presentation	Common causative flies
Furuncular myiasis	Presents as boil-like (furuncle-like) nodules in skin; often with central punctum, sometimes with serous discharge; patients may feel movement or pain; larvae localized in a discrete lesion.	Dermatobia hominis, Cordylobia anthropophaga, Wohlfahrtia vigil, Cuterebra spp.
Creeping (migratory) myiasis	Larvae move through subcutaneous tissues, producing serpiginous / linear tracks rather than a fixed nodule; may present as migrating eruption.	Flies such as Gasterophilus, Hypoderma spp.
Wound (traumatic) myiasis	Occurs in preexisting wounds, necrotic tissue, ulcers etc.; multiple larvae may infest; often more destructive; secondary bacterial infection risk is higher.	Screwworm flies like Cochliomyia hominivorax, Chrysomya bezziana, Wohlfahrtia magnifica etc.

Furuncular myiasis, one of the most recognizable forms of myasis, typically presenting with painful nodules containing developing larvae. Diagnosing myiasis is primarily clinical, relying on a patient’s medical history and physical examination. Accurate differential diagnosis of Dermatobia hominis myiasis and knowledge of appropriate treatment strategies are becoming increasingly important for healthcare providers in fields such as primary care, dermatology, surgery, and other specialties that manage patients returning from international travel. Although species-level identification was not performed in our patient, laboratory confirmation through microscopic or molecular methods (e.g., PCR) would have been useful for precise etiological determination and epidemiological surveillance. Such an approach would enhance both clinical management and epidemiological understanding.

In most cases, including the one described, myiasis tends to affect exposed and accessible parts of the body where flies can lay their eggs, such as the limbs or neck. However, it can sometimes occur in less exposed areas, including the inguinal and genital regions, the breasts, and the scalp [4]. Myiasis is also categorized according to the anatomical location it affects, including cutaneous (the most common form), ophthalmic, auricular, buccal, nasal, intestinal, and others [15].

Dermatobia hominis usually produces single lesions (a single larval nodule) because each larva develops independently at the inoculation site. However, it is possible to find several simultaneous lesions, as in this clinical case. In addition, it is important to note that Chrysomya myiasis can also be seen in the Americas, such as Lucilia spp. Both have cuticles with bands of spines that allow them to invade tissue, just like Dermatobia hominis [16].

The incubation period for furuncular myiasis typically ranges from a few days to several weeks, depending on the species involved. In this case, the onset of symptoms approximately one month after travel is consistent with the known incubation period. Importantly, the patient denied any history of pre-existing lesions on the affected limb, supporting the conclusion that the infestation developed de novo following exposure abroad. This case is illustrative of the diagnostic challenge of furuncular lesions in travelers. In the absence of a crawling sensation or visible larva, the condition is frequently misdiagnosed as cellulitis, abscess, or even spirochetal infection. Key clinical clues include persistent nodules with central punctum, serous drainage, and a recent history of travel to endemic areas. Ultrasound might be useful for diagnosing myiasis and locating larvae before extraction. Magnetic resonance imaging or computed tomography may be helpful in rare or atypical cases, especially in uncommon anatomical sites [4]. Details about travel history (countries and region where the patient traveled, exact period of travel) are very important to communicate to the laboratory, as they can be useful for species-level identification in cases of myiasis. Delays in diagnosis may result in inappropriate antibiotic use and prolonged morbidity.

Management typically involves mechanical or surgical extraction of the larva, local wound care, and surveillance for secondary infection. In our patient, the evolution was favorable with minimal intervention once the correct diagnosis was established. Among the 90 patients diagnosed with myiasis in the study published by Lachish T et al. in 76% of cases, manual extraction was sufficient to remove the larva and 24% required surgical intervention. Most patients did not receive antibiotic treatment, but secondary infection was noted in only one patient, upon partial removal of the larva [13].

Many treatment schemes have been suggested, including the application of highly dense liquids (petroleum jelly, liquid paraffin, beeswax, nail polish) and adhesive tape to the lesion to cause anoxia in the Dermatobia hominis larvae [12].

Larva should be removed intact to avoid hypersensitivity reaction to the larval antigens [17]. Ivermectin, a larvicide used in the treatment of livestock was successfully used in the treatment of human myiasis [18].

While the outcome in this case was benign, the absence of preventive measures can lead to significantly more serious consequences. Therefore, promoting access to and the use of travel medicine services remains a key component in safeguarding the health of international travelers in an increasingly mobile world. This situation underscores the critical need to raise awareness about the importance of pre-travel medical consultations. Myiasis can be prevented through personal protective strategies aimed at avoiding mosquito bites. These include applying insect repellent to exposed skin, using mosquito nets treated with permethrin or deltamethrin, and wearing clothing that covers as much of the body as possible.

These precautions are important, as removing larvae becomes more difficult as they mature. In the early stages, larvae can be expelled with gentle lateral pressure. However, as they develop, they grow anchoring spines and their front end enlarges. In advanced stages, surgical intervention may be necessary to ensure complete removal [15].

This case also reflects the persistently low utilization of travel medicine consultations in Romania, despite the growing interest in exotic destinations. The traveler’s itinerary would have warranted a series of vaccinations and counseling regarding the use of insect repellents, as well as advice on preventing traveler’s diarrhea. Fortunately, despite the lack of precautionary measures, the traveler developed only a single health issue—dermatologic in nature—highlighting the well-known fact that skin conditions are among the most common health problems encountered by international travelers, particularly in tropical and subtropical regions.

Conclusions

With the growing popularity of travel to tropical regions, healthcare providers in non-endemic areas are increasingly likely to encounter infections caused by parasitic flies. Clinicians should maintain a high index of suspicion for cutaneous myiasis in returning travelers with non-healing nodular lesions. Regardless of the fly species, the effective treatment remains the extraction of the larvae.

Author contributions

Ana-Maria Blănaru: Contributed to case management, data collection, literature review provided clinical images and wrote the case description and discussion section. Approved the final manuscript and agreed to be accountable for its contents. Andreea Ruxandra Toderan: Performed diagnostic evaluation, contributed to the case presentation and drafted the discussion section. Approved the final manuscript and agreed to be accountable for its contents. Adriana Oancea: Performed diagnostic evaluation, contributed to literature review and drafted the background section. Approved the final manuscript and agreed to be accountable for its contents. Adriana Hristea: Conceived the case report, supervised manuscript preparation, and critically revised the final version. Approved the final manuscript and agreed to be accountable for its contents.

Funding

The authors received no specific funding for this work.

Data availability

No datasets were generated or analysed during the current study.

Declarations

Ethics approval and consent to participate

Not applicable. This article reports a single case report based on routine clinical care and does not involve a prospective study, human experimentation, or the use of human tissue requiring ethics committee approval.

Consent for publication

Written informed consent was obtained from the patient for publication of this case report and any accompanying images.

Competing interests

The authors declare no competing interests.