Abstracts & Commentary
Synopsis: Two recent publications cover common issues pertinent to travelers. There is a new way to expedite the diagnosis and treatment of myiasis, which is reviewed below. Included is also a synopsis of an illustrative article to make available to those who give advice to travelers regarding health care abroad.
Sources: Boggild AK, et al. Furuncular myiasis: a simple and rapid method for extraction of intact Dermatobia hominis larvae. Clin Infect Dis. 2002;35:336-338; Kolars JC. Rules of the road: A consumer’s guide for travelers seeking health care in foreign lands. J Travel Med. 2002; 9:198-201.
A case of furuncular myiasis complicated by staphylococcal infection and streptococcal cellulitis was recently published describing diagnostic issues and complications for this common skin nuisance, its misdiagnosis, and its occasional bacterial superinfections. A novel approach seems to facilitate the extraction of this parasite. The reported case was a 34-year-old male archeologist who presented to an outpatient clinic with a skin lesion on his lower leg that had developed 1 week previously. The patient was treated with oral antibiotics for what was thought to be a bacterial abscess. When there was no subsequent clinical response and his travel history revealed recent travel to Belize, he was referred to the Tropical Disease Unit at the Toronto General Hospital for reassessment.
On further analysis of this process the lesion had evolved from a small painful bump over the course of 4 weeks to a large red lesion that intermittently drained serosanguineous fluid. He had noted a sensation of movement within the lesion accompanied by stabbing pains. Despite antibiotics the lesion and the surrounding skin had become increasingly red, swollen, and tender. On examination of his leg there was a fixed, indurated erythematous 2 cm nodule that had a central punctum leaking serous fluid. Extensive associated cellulitis and edema up to the knees were noted although the patient was afebrile. Cultures of this fluid grew Staphylococcus aureus amd group G Streptococcus. Outpatient treatment with cloxacillin was initiated along with an occlusive dressing containing petroleum jelly that was placed over the lesion in an attempt to suffocate a presumed fly larva. On follow-up 18 hours after the occlusive dressing had been worn, it was removed and the posterior end of a Dermatobia hominis maggot was found to be moving and protruding through the punctum. Suffocation therapy had failed, and lateral pressure was applied to the margins of the lesion; however, the larva could not be extracted. To facilitate removal the attending clinician applied a snake-venom extractor (The Extractor; Sawyer Products) to the lesion according to the manufacturer’s instructions. This resulted in rapid removal of an intact motile maggot 1.5 cm in length. The patient subsequently had an uneventful recovery.
Comment by Maria D. Mileno, MD
The innovative approach applied here has the potential to both become a treatment of choice for furuncular myiasis and to replace "tried-and-true" extraction methods. These often require suffocation of the maggots and pressure applications that take time to perform, yet often fail. Anecdotes concerning various cuts of meat, mineral oil, petroleum jelly, pork fat, superglue, nail polish, and chewing gum applied to such lesions for suffocation are entertaining but generally impractical. Surgical extraction is more often required but may be complicated if there is accompanying cellulitis.
Myiasis represents infestation of human or animal tissues by fly larvae (insect order Diptera.) Human travelers are most often accidental hosts to a benign process. However, facultative infestation (eg, eggs laid on malodorous or festering wounds) may result in considerable pain and tissue damage as fly larvae leave necrotic tissues to invade healthy areas. Obligate myiasis (eg, true parasitism that is necessary for fly development) can be serious or even fatal, as fly larvae feed on healthy tissues. Numerous species of flies have been implicated in facultative myiasis including blowflies (Calliphoridae), the rat-tailed maggot (Eristalis tenax), the black blowfly (Phormia regina), and the housefly (Musca domestica), as well as the latrine fly (Fannia scalaris) associated with urinary or rectal myiasis.
Human botfly (Dermatobia hominis) transmission does not occur in the United States; however, numerous cases are seen by North American physicians evaluating those who return from cruises or vacations to endemic areas. Lesions of the botfly, which are often localized to the scalp, face, forearms, and legs, reflect the unique life cycle of the organism. The botfly preferentially deposits its eggs on the underside of a mosquito. Botfly eggs drop off the mosquito as it feeds on animals. Birds, humans, and other mammals are often targets. Then eggs hatch, producing larvae that penetrate the skin and reside in the subcutaneous tissue for about 100 days. The third-stage maggot exits via the punctum, falls to the ground and pupates during the next 2-3 weeks. Then the fly emerges as an adult, living only for 8 or 9 days during which time it mates and pastes its eggs to the abdomens of mosquitoes or other blood-sucking arthropods to complete the life cycle. Individuals who participate in ecoturism and rural outdoor occupations in areas such as Central and South America, where this forest-dwelling fly is commonly found, are at risk of developing myiasis.
Screw-worm flies are also obligate parasites of living flesh. The Old World species (Chrysomyia bezziana) is found in tropical Africa and Asia, and the New World species (Cochliomyia hominivorax) was at one time distributed from the southern United States to southern Brazil. The Tumbu fly (Cordylobia anthropophaga) is a major cause of cutaneous myiasis in tropical Africa. The adult fly is distinguished by its yellow-brown body and small size (6-12 mm). Lastly a sarcophagid fly, Wohlfahrtia magnifica is distributed over warmer regions of Europe, Asia, northern Africa, the Middle East, and the Mediterranean. Like the screw-worm fly it deposits actual larvae and often can invade mucous membranes, ie, landing inside the nostril while a person sleeps in the daytime.
The following 10 rules of the road are good common sense excerpts regarding health care abroad, which are embellished nicely in the second article.
- Do not assume that the health care system is at all similar to the one you left at home.
- Seek out units that have a reputation of caring for foreigners.
- Clarify payment issues from the start.
- Make the doctors/nurses comfortable and willing to help you.
- Avoid leveraging knowledge from your home country in hopes of "educating" the local providers about what needs to be done.
- Understand that in some cultures, questions from patients or family members are often perceived as challenges to the authority of the doctors.
- Decide which issues you will try and influence and which you are going to leave alone.
- Have "exit strategies" prepared in advance that allow you to bow out gracefully from the care (and for the local providers to save face) if you are dissatisfied.
- Watch for explicit/implicit incentives for people directing your care.
- Carefully consider evacuation/travel insurance.
The table provided from this article is an excellent reference to keep handy, since it contains a partial listing of companies and organizations that provide evacuation and travel insurance services.
Dr. Mileno, Director, Travel Medicine, The Miriam Hospital, Assistant Professor of Medicine, Brown University, Providence, RI, is Associate Editor of Travel Medicine Advisor.
1. Goddard J. Arthropods, tongue worms, leeches, and arthropod-borne diseases. Tropical Infectious Diseases. 1999;2:1325-1342.