How Monkeypox Is Diagnosed

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Like many other viruses, monkeypox cannot be diagnosed by symptoms alone. Although infections are sometimes treated based on symptoms (typically in areas where an outbreak is occurring), lab testing is needed to confirm the diagnosis and ensure that monkeypox is the cause and not some other disease.

Monkeypox is diagnosed with lab tests that detect genetic evidence of the virus from a swab of a skin sore. Blood tests and other lab tests may be used to rule out diseases that look similar to monkeypox, such as chicken pox or syphilis.

This article walks you through what is involved in diagnosing monkeypox, including when monkeypox testing is recommended.

Swabs to be tested for monkeypox virus

Sebastian Condrea / Getty Images

Self-Checks

There are no at-home tests to diagnose monkeypox.

While you may assume you have monkeypox because you've been in contact with someone who has it, the signs and symptoms can vary from one person to the next. In the early stages, there may only be mild, flu-like symptoms (like fever, headache, muscle pain, and fatigue) or no symptoms at all.

The first recognizable sign of monkeypox is the appearance of a characteristic blister-like rash on the skin. Although rash symptoms can vary, there are some tell-tale signs to look out for, including:

  • Rash distribution: Typically, the rash starts on the face before moving to the trunk and then elsewhere on the body, such as on the palms of the hands and soles of the feet.
  • Sexual exposure: If the virus is transmitted through sexual contact, the rash may start on the groin, genitals, or anus and either remain there or spread to other parts of the body, such as the arms, trunk, legs, and face.
  • Number of rashes: The rash may involve only one or two pimple-like bumps or as many as 200 or more bumps.
  • Rash appearance: The bumps rapidly grow into firm, blistery lesions filled with clear fluid and then pus. These pus-filled bumps eventually burst and scab over.
  • Pain and itch: The bumps can be extremely painful until they burst, after which the sores are more itchy than painful as they start to heal.

Who Is at Risk?

During the 2022 outbreak in the United States, most monkeypox cases were among men who have sex with men (MSM) exposed through intimate or sexual contact. Even so, the Centers for Disease Control and Prevention (CDC) reports that anyone can get monkeypox regardless of age, race, ethnicity, sex, gender identity, or sexual orientation.  

Physical Exam

Most people seek a diagnosis for monkeypox after a painful, unexplained rash develops. The diagnosis typically starts with a review of your symptoms, medical history, and risk factors for infection (including recent sexual exposures).

The healthcare provider will then perform a physical exam to check for the usual signs and symptoms of infection.

With monkeypox, the rash will develop in a characteristic pattern—from bumps to blisters to pus-lesion lesions—before breaking open and crusting over. They tend to develop and evolve simultaneously. Those occurring around the anus may be accompanied by rectal pain, bleeding, or a pus-like discharge.

The timing of the rash outbreak is also key as it tends to develop three to 17 days after a suspected exposure.

How Monkeypox Differs

One of the signs that differentiates monkeypox from similar viral infections like chicken pox is lymphadenopathy (swollen lymph nodes). With monkeypox, swollen lymph nodes may appear behind the ear, below the jaw, in the neck, or in the groin, often before the rash even appears.

Labs and Tests

Monkeypox is diagnosed definitively with a swab of an open sore. The swab is then sent to a lab for evaluation using polymerase chain reaction (PCR) technology.

PCR works by amplifying (multiplying) the genetic material of the virus, called DNA, to levels at which it can be positively identified. PCR is used to diagnose many diseases and to customize treatments based on the characteristics of the person's DNA.

Only a healthcare provider can order a monkeypox test. The provider may either take the swab themselves or send you to a lab to get one.

Here is what to expect when undergoing monkeypox testing:

  • The healthcare provider will rub the swab vigorously over open lesions to obtain a sample of fluid and cells. More than one lesion will be swabbed.
  • The procedure may be a little uncomfortable, but obtaining an ample quantity of genetic material is necessary.
  • Once the swab is submitted to the lab, the test results should be returned within a few days.
  • Until the results are received, you will be advised to take standard precautions to avoid spreading the virus to others.

CDC Testing Recommendations

According to the CDC, testing is only recommended for people with a rash consistent with monkeypox. Because the test relies on a sample of fluid from a lesion, it is of little value if you have no lesions.

What Test Results Mean

The results of the monkeypox test, called the orthopoxvirus PCR, are pretty straightforward and mean one of the following:

  • Positive: This means that you have monkeypox and need to take precautions to avoid transmitting it to others until you are completely recovered. You are considered contagious until all scabs have fallen off and the skin beneath has amply healed.
  • Negative: This means that no evidence of monkeypox DNA was found and you probably do not have monkeypox. Even so, you should continue to take steps to protect yourself and others.
  • Inconclusive: This means that the results of the test are unclear (usually because not enough of a specimen was obtained) and the test needs to be repeated.

Differential Diagnosis

Although monkeypox has distinguishing features (such as pain and swollen lymph nodes) and tends to occur in outbreaks (including the 2022 outbreak affecting over 100 countries), the signs and symptoms are often distinguishable from many other viral and non-viral diseases.

Because of this, your healthcare provider may opt to run other blood, tissue, or urine tests to rule out conditions with similar features. This is referred to as a differential diagnosis.

Among some of the conditions that may be explored in the differential diagnosis are:

Summary

While monkeypox may be recognized by the outbreak of a painful, blister-like rash, it can only be diagnosed with a lab test. The test involves a swab of fluid from an open sore, which is sent to a lab for evaluation. The results are usually received within a few days.

Other lab tests may rule out infections or diseases with similar features, such as genital herpes, MRSA, or chicken pox.

A Word From Verywell

If you think you've been exposed to monkeypox, don't wait until symptoms appear; tell your healthcare provider as soon as possible. Monkeypox vaccines are available which may help avert the infection if given within four days of the exposure.

Vaccination is also advised for men who have sex with men (MSM) if they have had group sex, sex in a commercial sex venue, or multiple sex partners within the prior two weeks. The same applies to transgender or gender-diverse people who have sex with men.

Frequently Asked Questions

  • How long does monkeypox last?

    Most people recover from monkeypox within two to four weeks. Symptoms usually start within three weeks of exposure to the virus. The initial flu-like symptoms may be followed by a rash one to four days later.

  • How do you treat monkeypox if you get it?

    There are no specific treatments for monkeypox. But, because the viruses that cause monkeypox and smallpox are similar, an antiviral drug used to treat smallpox, called tecovirimat (TPOXX), may help. TPOXX is generally reserved for those who are at risk of severe infection, such as people with advanced (human immunodeficiency virus (HIV).

  • Can monkeypox kill you?

    Monkeypox, a viral infection similar to smallpox, is rarely fatal. Of the roughly 60,000 infections reported worldwide in 2022, only around 20 deaths have occurred. With that said, monkeypox can be excruciatingly painful for some people and can cause permanent scarring.

19 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By James Myhre & Dennis Sifris, MD
Dennis Sifris, MD, is an HIV specialist and Medical Director of LifeSense Disease Management. James Myhre is an American journalist and HIV educator.