A few days after the treatment for the blastocystis, the gastrointestinal tract symptoms improved, but dermatologic, ocular, pulmonary, and cardiac symptoms persisted. She also began experiencing night sweats and hot flashes. In between visits to the primary care physician, she sought medical attention at an urgent care clinic for worsening pulmonary and cardiac symptoms. At that time, results of a chest radiograph were normal.
The primary care physician referred her to infectious disease and dermatology for further evaluation within a few weeks of returning to the United States. Upon presentation to dermatology, the patient described a waxing and waning nature to the rash on the arm with associated intermittent pain. Physical examination revealed several erythematous patches on the triceps and a 1-cm subcutaneous nodule on the right elbow with overlying skin discoloration. The patient stated that she first noticed the inflamed painful nodule when she returned to the United States. Since its discovery, the nodule increased in size and became firm. The patient also described occasional limited range of motion of the right arm due to the discomfort of the rash and inflamed nodule. Interestingly, the patient’s partner who accompanied her to Peru also developed a similar pruritic rash on the chest. He was evaluated by dermatology and infectious disease; however, biopsies of his rash performed at a different practice revealed nonspecific results. Due to her partner’s inconclusive results, our patient initially refused a biopsy; however, she returned to the office after 1 week with worsening symptoms, and a 4-mm punch biopsy of the right arm was obtained in addition to rapid plasma reagin and QuantiFERON-TB Gold test.
Based on the patient’s travel history, clinical course, and physical examination, the clinical differential diagnosis included nummular dermatitis, panniculitis/nodular vasculitis, tinea corporis, secondary syphilis, pinta, tuberculosis, or cutaneous filariasis. Rapid plasma reagin and QuantiFERON-TB Gold test results were negative, and a periodic acid–Schiff stain of the biopsy was negative for fungal elements. Dermatopathology revealed intradermal filarial nematodes of 120 to 150 µm in diameter and 1-to 2-mm cuticles eliciting a predominantly superficial and deep lymphohistiocytic reaction (Figure 3). The histopathologic differential diagnosis based on the diameter of the nematode included M perstans, W bancrofti, and O volvulus. Clinical correlation was highly recommended to obtain a final diagnosis and management plan. A portion of the biopsy was sent to the Centers for Disease Control and Prevention, which confirmed the presence of a filarial nematode consistent with a zoonotic Brugia but also with zoonotic Onchocerca as a possible differential. Therefore, considering the history, clinical course, and histopathologic analysis, the final diagnosis of cutaneous onchocerciasis was made.
Figure 3. A–C, Histopathology demonstrated intradermal filarial nematodes with a superficial and deep lymphohistiocytic reaction (H&E; original magnifications ×100, ×400, and ×400, respectively).
The patient was referred back to infectious disease and started on combination therapy of ivermectin (25.5 mg) plus albendazole (800 mg) taken at once followed by doxycycline (200 mg) for 6 weeks. The symptoms initially worsened, then she experienced near-complete resolution of dermatologic, pulmonary, and ocular symptoms after approximately 2 weeks of treatment. She continued to report fatigue and palpitations, for she continued to see a cardiologist. We highly encouraged her to continue following up with infectious disease to ensure complete eradication of the infection.
Onchocerciasis is common in individuals who live or work in equatorial Africa, Central America, and South America. The disease process has dermatologic, ocular, and other systemic manifestations if the infection continues long-term without treatment.2,5 Although rare, this infection has been observed in US citizens who have traveled to filarial endemic regions for a period of time ranging from 2 weeks to 39 years.2,6,7
Blackflies (genus Simulium), the intermediate host of O volvulus, breed in areas close to freely flowing water. The blackfly bites a human host, and within 7 days the microfilariae undergo 2 molts to reach the infective stage. The larvae remain in the dermis and subcutaneous tissue for 2 additional molts until they develop into adult worms. Then, adult worms may become encapsulated, eliciting and forming subcutaneous nodules, also known as onchocercomas.2,3