Disease Overview

Monkeypox is a zoonotic disease caused by monkeypox virus, an enveloped double-stranded DNA virus that belongs to the Orthopoxvirus genus. Other clinically important viruses of the Orthopoxvirus genus are variola virus (the causative agent of smallpox), vaccinia virus (used in the smallpox vaccine), and cowpox virus. Monkeypox was first identified as the causative agent of two pox-like disease outbreaks in monkey colonies housed for research in 1958. Although the exact natural host remains unknown, the monkeypox virus has been isolated from rope squirrels, tree squirrels, Gambian pouched rats, dormice, non-human primates, and other species.

First case of human monkeypox was identified in 1970 in the Democratic Republic of the Congo in a 9 month-old child.

First case associated with the current 2022 outbreak of monkeypox was confirmed in the United Kingdom on May 6.

As of August 1, 2022, 5,811 confirmed cases have been reported in the U.S.

More than 23,000 cases of monkeypox have been confirmed globally in 73 non-endemic countries.

Transmission and Incubation Period

Animal-to-human transmission of monkeypox virus occurs through direct contact with the blood, bodily fluids, or cutaneous or mucosal lesions of infected animals. Human-to-human transmission typically occurs through contact with infectious respiratory secretions, skin lesions of an infected person or recently contaminated objects. Most cases in the current outbreak have been identified in men who have sex with men, leading to the possibility that monkeypox can be transmitted through sexual transmission routes. Transmission can also occur through contact with materials or fomites (e.g. clothing or linens) that have been contaminated with bodily infectious materials. Transmission has also been reported via droplet respiratory particles, via the placenta from mother to fetus or via close contact during and after childbirth.

The incubation period of monkeypox can be 5 to 21 days but typically ranges from 6 to 13 days. The disease manifestation can be divided into two periods:

      Invasion Period

The initial prodromal/invasion period is characterized by fever, intense headache, lymphadenopathy, back pain, myalgia and intense asthenia within 5 days of infection.

      Rash/Skin Eruption

The rash/skin eruption usually occurs within 1 to 3 days of the appearance of fever and continues for a period of 2 to 3 weeks. The rashes are usually concentrated on the face and extremities (palms of the hands and soles of the feet). Other affected sites may include oral mucous membranes, genitalia, and conjunctivae, as well as the cornea. The rash progresses successively from macules to papules, vesicles, pustules, and crusts that dry up and fall off. The number of lesions can be highly variable, from a few to several thousand. In severe cases, lesions can coalesce until large sections of skin slough off.

The disease is generally self-limiting and the symptoms last from 2 to 4 weeks. An individual remains infectious from the onset of illness until all lesions have scabbed over and re-epithelialization has occurred. Complications of monkeypox can include secondary infections, bronchopneumonia, sepsis, encephalitis, and infection of the cornea with ensuing loss of vision. Severe cases and complication may occur in children and immunocompromised hosts. Asymptomatic infections have been documented but the frequency/prevalence of asymptomatic infections is unknown.

About Our Test

Sonic Reference Laboratory's Monkeypox Virus by PCR test methodology is real-time PCR utilizing the CDC Non-variola Orthopoxvirus Real-time PCR Primer and Probe Set. The assay detects non-variola Orthopoxvirus DNA in clinical specimens. Although this assay does not differentiate monkeypox virus from other Orthopoxvirus including vaccinia, cowpox, camelpox, ectromelia or gerbilpox virus, a positive result with this assay in the United States is most likely due to monkeypox virus; however, potential exposure to other Orthopoxviruses should be considered. The test results are intended to be utilized in conjunction with clinical presentation, epidemiological data, other diagnostic test results, and vaccination and exposure history. As monkeypox virus infections can present with rashes/lesions similar to that of varicella zoster virus, herpes simplex virus, and other sexually transmitted infections, consider testing for other pathogens as clinically indicated.

Test Ordering Information

Order Code: Contact your laboratory partner
Test Name: MONKEYPOX VIRUS PCR
Ordering Recommendation: For detection of non-variola Orthopoxvirus, including monkeypox virus, DNA in clinical specimens
Test Contains (LOINC): Monkeypox Virus PCR (100434-0), Specimen (31209-2), Symptomatic (95419-8), Symptom Onset Date (11368-8)
Sample Type: Swabs from skin lesion
Preferred Container: Sterile screw cap tube with O-ring or gasket seal
Alternate Container: Leak-proof sterile screw cap tube
Sample Volume: Two swabs
Handling Instructions: Vigorously swab or brush active lesion with two separate sterile synthetic swabs (e.g. Dacron, polyester, or nylon) with a plastic shaft and breakpoint close to the tip. Do NOT use cotton swabs. Break off or cut the tip of each swab into a sterile tube or container. Each swab should be placed in a separate tube or container. Parafilm may be used to ensure a leak-proof lid if the tube does not have an O-ring or gasket seal. The length of the swabs after breaking or cutting should be no longer than 35mm (1.5 in.). Do NOT add transport media to specimens. Refrigerate or freeze specimen immediately after collection. Freezing is strongly recommended. To maintain optimum specimen viability, transport the specimen to the laboratory as soon as possible.
Transport: Frozen on dry ice
Specimen Stability: Refrigerated: 7 Days; Frozen: 1 Month
Unsuitable Specimen: Single swab. Cotton swabs. Swabs with wooden or metal shafts. Swabs in media designed for preservation and/or transport. Out of stability specimens.
Frequency: Monday, Tuesday, Wednesday, Thursday, Friday
Expected Turn Around: 2 - 3 Days
Reference Range: Negative
Responsible Department: Molecular
NYSDOH Approval Status: Approved
CPT: 87593
Methodology: Real-Time Polymerase Chain Reaction (RT-PCR)

References:

  1. US Monkeypox outbreak 2022. CDC’s 2022 U.S. Map & Case Count. https://www.cdc.gov/poxvirus/monkeypox/response/2022/us-map.html
  2. Global Monkeypox outbreak 2022. CDC. https://www.cdc.gov/poxvirus/monkeypox/response/2022/world-map.html
  3. KD Reed, et al., The detection of monkeypox in humans in the Western Hemisphere. N Engl J Med. 2004. 350, 342– 350. https://pubmed.ncbi.nlm.nih.gov/14736926/
  4. Sklenovská N, Van Ranst M. Emergence of Monkeypox as the Most Important Orthopoxvirus Infection in Humans. Front Public Health. 2018 Sep 4;6:241. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6131633/
  5. Monkeypox fact sheet. World Health Organization. https://www.who.int/news-room/fact-sheets/detail/monkeypox
  6. Laboratory Procedures and Biosafety Guidelines. CDC. https://www.cdc.gov/poxvirus/monkeypox/lab-personnel/lab-procedures.html
  7. Collection, Storage, and Shipment of Specimens for Monkeypox Diagnosis. CDC. https://www.cdc.gov/poxvirus/monkeypox/clinicians/prep-collection-specimens.html