Clinicians should consider the possibility of novel poxviruses when presented with cutaneous infections, particularly in patients with known exposure to barnyard animals, according to recent findings.
In the study, researchers characterized two cases of a cutaneous poxvirus infection caused by an unknown, currently unclassified virus. The first case, a female aged 17 years from Tennessee who owned and cared for a horse, presented with an erythematous macule on her right cheek. The patient had undergone orthotopic heart transplantation in 2007 and was being maintained with tacrolimus and mycophenolate-mofetil. The macule grew, and the patient developed new lesions that were painful and pruritic. These lesions advanced from macules to papules and eventually grew into 1-cm to 1.5 cm brown nodules. A right temple lesion was excised, and histopathology showed ballooning keratinocytes with eosinophilic cytoplasmic inclusions consistent with a poxvirus infection.
After treatment with imiquimod for 2 weeks failed to halt lesion progression, the CDC was enlisted to confirm poxvirus infection. A dermatologist excised the larger lesions, and the smaller lesions were removed through cryotherapy.
The second case occurred in a woman aged 28 years from Missouri who developed a nodule between her right index finger and thumb. This patient had traveled to Tanzania, where she cared for donkeys and dogs. While rescuing a donkey from a watering hole, the patient’s hands were submerged in murky water. The patient was referred to an infectious disease specialist and dermatologist, and the physician excised the lesion for dermatopathologic analysis. Histopathology revealed eosinophilic inclusions consistent with poxvirus infection. The patient underwent a regimen of oral doxycycline and levofloxacin, and symptoms resolved within 4 to 5 days.
Genetic analysis of samples from both patients suggested the presence of a novel poxvirus. Additional analysis indicated that the virus was 88% similar to viruses in the Parapoxvirus genus and 78% similar to the molluscum contagiosum virus. Of 83 specimens collected from the animals that came in contact with the patients, none tested positive for the poxvirus using a pan-pox PCR assay.
According to the researchers, the origin of the virus could not be determined, but this does not preclude the possibility of zoonotic transmission.
“Although we were unable to identify the source(s) of this novel poxvirus, we recommend the use of nonporous gloves for persons in contact with stable or barn environments, or involved in animal handling, particularly those individuals that are immunosuppressed or have open wounds on the hands,” the researchers wrote. “Also, all open wounds should be covered when handling animals, and skin should be immediately washed after contact with animals as poxviruses are known to infect damaged skin.”
Disclosure: The researchers report no relevant financial disclosures.