Monkeypox Workup

  • Author: Mary Beth Graham, MD; Chief Editor: William D James, MD   more...
 
Updated: May 8, 2012
 

Laboratory Studies

Information regarding procurement and disposition of specimens for the CDC may be obtained at Laboratory Testing of Human and Animal Specimens.

A viral culture should be obtained from an oropharyngeal or nasopharyngeal swab. A skin biopsy specimen of the vesiculopustular rash or a sample of the roof of an intact vesiculopustule should be analyzed.

Tissue for PCR of DNA sequence-specific for the monkeypox virus may be obtained.

Paired sera for acute and convalescent titers may be analyzed. Serum collected more than 5 days for IgM detection or serum collected more than 8 days after rash onset for IgG detection was most efficient for the detection of the monkeypox virus infection.[7]

A Tzanck smear can help differentiate monkeypox from other nonviral disorders in the differential diagnosis. However, a Tzanck smear does not differentiate a monkeypox infection from smallpox or herpetic infections.

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Histologic Findings

Histologically, papular lesions show acanthosis, individual keratinocyte necrosis, and basal vacuolization. This is accompanied by a superficial and deep perivascular, lymphohistiocytic infiltrate in the dermis. Lesions in the vesicular stage demonstrate spongiosis with reticular and ballooning degeneration. Multinucleated epithelial giant cells may be seen. Pustular lesions are characterized by epidermal necrosis with numerous eosinophils and neutrophils, many displaying karyorrhexis. Necrosis may extend through full-thickness epidermis with sharp lateral demarcation from adjacent intact epidermis. The associated perivascular infiltrate includes eosinophils and neutrophils in addition to lymphocytes and histiocytes. Petechial lesions demonstrate secondary vasculitis. Amphophilic intranuclear structures suggestive of viral inclusions may be seen in keratinocytes.

Immunohistochemistry staining for orthopox viral antigens can be performed in a reference laboratory. With electron microscopy, intracytoplasmic, round-to-oval inclusions with sausage-shaped structures centrally, measuring 200-300 µm, are observed.[18] Inclusions are consistent with orthopox viruses, permitting differentiation from parapox and herpes viruses.

Diagnostic criteria

The diagnostic criteria are summarized below; refer to the current criteria established by the CDC at Updated Interim Case Definition for Human Monkeypox, January 2004.

Confirmed case

Meets 1 or more of the following laboratory criteria:

  • Isolation of the monkeypox virus in culture from a sample obtained from the patient
  • Demonstration of the monkeypox virus on PCR in a specimen obtained from the patient
  • Demonstration of the orthopox virus by electron microscopy in samples obtained from the patient in the absence of exposure to other orthopoxviruses
  • Demonstration of the monkeypox virus by immunohistochemical methods in samples obtained from the patient in the absence of exposure to another orthopoxvirus

Probable case

This is contact that meets current epidemiologic criteria per the CDC. It is the occurrence of fever and vesicular-pustular rash, with the onset of the first sign or symptom at most 21 days after the last exposure, meeting the epidemiologic exposure.

Suspected case

This is contact that meets current epidemiologic criteria per the CDC. It the occurrence of fever or unexplained rash and 2 or more other signs or symptoms, with the onset of the first sign or symptom at most 21 days after exposure, meeting the epidemiologic criteria. Symptoms are as follows:

  • Chills and/or sweats
  • Lymphadenopathy
  • Sore throat
  • Cough
  • Shortness of breath
  • Headache
  • Backache
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Contributor Information and Disclosures
Author

Mary Beth Graham, MD  Associate Professor, Department of Medicine, Division of Infectious Diseases, Medical College of Wisconsin

Mary Beth Graham, MD is a member of the following medical societies: American College of Physicians, Infectious Diseases Society of America, and Society for Healthcare Epidemiology of America

Disclosure: Nothing to disclose.

Coauthor(s)

Juliet L Gunkel, MD  Assistant Professor, University of Wisconsin School of Medicine and Public Health; Consulting Physician, University of Wisconsin Hospital

Juliet L Gunkel, MD is a member of the following medical societies: American Academy of Dermatology, American College of Mohs Micrographic Surgery and Cutaneous Oncology, American Medical Association, American Society for Dermatologic Surgery, Wisconsin Medical Society, and Women's Dermatologic Society

Disclosure: Nothing to disclose.

Janet Fairley, MD  Professor and Head, Department of Dermatology, University of Iowa, Roy J and Lucille A Carver College of Medicine

Janet Fairley, MD is a member of the following medical societies: American Academy of Dermatology, American Dermatological Association, American Federation for Medical Research, and Society for Investigative Dermatology

Disclosure: Nothing to disclose.

Specialty Editor Board

Julie R Kenner, MD, PhD  Consultant, Clinical Research, Medical Affairs, VaxGen, Inc; Private Practice, Kenner Dermatology Center

Julie R Kenner, MD, PhD is a member of the following medical societies: American Academy of Dermatology and American Society of Tropical Medicine and Hygiene

Disclosure: Nothing to disclose.

David F Butler, MD  Professor of Dermatology, Texas A&M University College of Medicine; Chair, Department of Dermatology, Director, Dermatology Residency Training Program, Scott and White Clinic, Northside Clinic

David F Butler, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, American Medical Association, American Society for Dermatologic Surgery, American Society for MOHS Surgery, Association of Military Dermatologists, and Phi Beta Kappa

Disclosure: Nothing to disclose.

Jeffrey P Callen, MD  Professor of Medicine (Dermatology), Chief, Division of Dermatology, University of Louisville School of Medicine

Jeffrey P Callen, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, American College of Physicians, and American College of Rheumatology

Disclosure: Amgen Honoraria Consulting; Celgene Honoraria Safety Monitoring Committee

Catherine M Quirk, MD  Clinical Assistant Professor, Department of Dermatology, University of Pennsylvania

Catherine M Quirk, MD is a member of the following medical societies: Alpha Omega Alpha and American Academy of Dermatology

Disclosure: Nothing to disclose.

Chief Editor

William D James, MD  Paul R Gross Professor of Dermatology, Vice-Chairman, Residency Program Director, Department of Dermatology, University of Pennsylvania School of Medicine

William D James, MD is a member of the following medical societies: American Academy of Dermatology and Society for Investigative Dermatology

Disclosure: Elsevier Royalty Other

Additional Contributors

The authors and editors of eMedicine gratefully acknowledge the contributions of previous authors, Michael W. Peterson, DO, and Juliet L. Gunkel, MD, to the development and writing of this article.

References

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Vesicular rash on the dorsal aspect of the hand. Vesicopustules are seen; some have a central umbilication.
Umbilicated papule on the lower part of the leg. This smaller lesion still shows the typical umbilicated morphology.
Lymphadenopathy in monkeypox. Large nodes in the mandibular, cervical, or inguinal region are commonly seen in monkeypox. The presence of significant lymphadenopathy helps differentiate monkeypox from smallpox and chickenpox.
 
 
 
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