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A healthy 36-year-old female presented with 4 days of itchy lesions on the right upper extremity

A healthy 36-year-old female presented with 4 days of itchy lesions on the right upper extremity. She stated that she thought she was "bitten by an insect." On physical examination, six grouped vesicles were present with mild surrounding erythema. She had no systemic symptoms. She did have mild lymphadenopathy.

What's your diagnosis?

Varicella zoster virus

Herpes simplex virus

Monkeypox virus

Orf virus

Varicella zoster and monkeypox virus

In this patient, bacterial and viral cultures were taken and varicella zoster virus (VZV) was isolated. Additionally, Orthopox DNA by PCR and Monkeypox (mpox) virus DNA by PCR were detected. Herpes simplex virus and bacterial viral cultures were negative. Valacyclovir was started at the time of presentation and the patient’s lesions resolved without sequelae.

Mpox is a zoonotic double-stranded DNA virus that is part of the Orthopoxvirus family, including the West African and Central African variants. This disease presents similarly to smallpox, so most mpox research was conducted around the time smallpox was eradicated. It was not until 1970, when the disease was isolated from a patient with suspected smallpox in the Democratic Republic of the Congo (DRC), that human mpox was considered a distinct disease. An epidemic outbreak in the United States occurred in 2003 related to infected prairie dogs, and travel-related outbreaks have been more recently reported up until May 2022, in which mpox was reported in nonendemic areas including North America, Europe, and Australia. Most cases in this outbreak occurred in men who have sex with men (MSM), but this is not always the case, and mpox is not necessarily considered a sexually transmitted infection. Mpox presents similarly to smallpox and VZV, so using laboratory tests is important in diagnosing and tracking this disease.

Although it is not easily transmitted, the disease can spread through bodily secretions both directly and indirectly. Mpox typically begins with a prodrome that includes fever, headache, myalgia, and fatigue. This is followed by lymphadenopathy that precedes and coincides with rash development. The lymph nodes are firm, tender, may be painful, and are a defining factor in presentation that differs from smallpox and varicella. The rash typically starts on the face, then presents on the body in a centrifugal distribution. However, cases related to sexual transmission present with anogenital lesions. The lesions are characterized by a progression from maculopapular to vesiculopustular, and can vary widely in quantity.

Notably, individuals are contagious from the onset of the prodrome until the lesions have scabbed over and fallen off. The eruptive nature of the later lesions poses a threat of secondary infection, and is often accompanied by a second febrile period that signifies deterioration of the patient’s condition. Other signs of secondary infection are variable and include pulmonary symptoms, vomiting, diarrhea, ocular infections, and in rare cases, encephalitis. These sequelae are more common in unvaccinated and immunocompromised individuals. Long-term complications of mpox include pitted scarring from cutaneous lesions with children being more susceptible to severe disease. The mortality rate for the disease is very low. (As of May 10, 2023, there have been 30,395 mpox cases reported in the United States, and 42 deaths, according to the Centers for Disease Control and Prevention.)

There are a variety of diagnostic tests that can aid in mpox identification, but they are most strongly supported when combined with clinical and epidemiological data. The best, least invasive method includes collection of lesion exudate or crust on a swab, and viral DNA is best preserved by keeping the specimen in a cool, dry, and dark environment. PCR is considered the standard, and electron microscopy and immunohistochemistry are valid tests, but all modalities require sophisticated technicians with the proper laboratory equipment. This is limiting because many cases present in underserved areas that lack the facilities for proper, real-time analysis. Antigen and antibody-based tests can be used, but cross-reactivity of other orthopoxviridae limits confirmation of mpox infection. Vaccination status, history and location must be considered.

Vaccination is the chief form of prevention for mpox, although it is not considered entirely protective. Smallpox vaccination provides protection, but widespread administration of the vaccine is no longer practiced, and an estimated 70% of the global population is no longer vaccinated. Vaccination is recommended for anyone at risk of exposure, but as this is a live, attenuated vaccine, the immune status of the patient is important to keep in mind. Tecovirimat and other antiviral medications including cidofovir and brincidofovir may be considered in severe cases.

This case is unique as our patient, who had no known risk factors for mpox, presented with mpox and VZV, simultaneously. Although clinical presentation and epidemiological patterns between these diseases differ, there have been a limited number of cases of coinfection reported in the literature, mainly in the DRC where mpox is endemic. Diagnosis must be made by separate laboratory tests and there are differences in presentation between independent and coinfection for these viruses. Notably, patients with mpox/VZV coinfection may be less likely to present with lesions on the face, thorax, arms, palms, and soles than those with only mpox but experience a higher lesion burden than those afflicted by only VZV. Coinfection may be related to reactivation of dormant VZV, or increased susceptibility to secondary infection when infected with one virus.

This case and photo were submitted by Lucas Shapiro, BS, of the Dr. Kiran C. Patel College of Osteopathic Medicine at Nova Southeastern University, Fort Lauderdale, Fla., and Donna Bilu Martin, MD.

Dr. Bilu Martin is a board-certified dermatologist in private practice at Premier Dermatology, MD, in Aventura, Fla. More diagnostic cases are available at To submit a case for possible publication, send an email to


1. Macneil A et al. Clin Infect Dis. 2009 Jan 1;48(1):e6-8.

2. Di Gennaro F et al. Microorganisms. 2022 Aug 12;10(8):1633.

3. Hughes CM et al. Am J Trop Med Hyg. 2020 Dec 7;104(2):604-11.

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