But while a monkeypox test already existed, it required lab workers to do each step by hand, Morice says. Federal guidelines say that testing should only be done by sampling the lesions of a person suspected of having the virus. These lesions look like pimples or blisters and can appear on the face, hands, feet, around the genitals or anus, or inside the mouth or rectum. The swabs then undergo a PCR, or polymerase chain reaction, test, which involves extracting genetic material and amplifying it to look for the presence of monkeypox virus DNA. When done manually, it means multiple steps of adding liquid, mixing reagents, and isolating the DNA.
This makes tests run slowly. Commercial laboratories such as the Mayo Clinic have worked to automate the process. Until recently, the clinic was only able to process 20 to 30 tests a day using the manual protocol, but soon it will be able to run several hundred tests a day, Morice says.
This kind of testing also raises some other problems. “The current tests force you to inoculate a lesion. For people with internal lesions, that might not be possible or it’s very painful,” says Makofane.
A monkeypox test cannot be given until a person has visible symptoms – and it can take several days for a rash to appear. Some people may have very subtle or very few lesions. While it’s not clear whether the disease can spread before the blisters form, Rivers says it would be better to catch an infection earlier so people can access treatment and vaccines as soon as possible. For the best chance of preventing outbreaks of the disease, the CDC says, the vaccine should be given within four days of the date of exposure.
Like Covid-19 tests in the early days of the pandemic, monkeypox tests must be ordered by a doctor. Morice says many doctors may not know whether to test for monkeypox because it is such a new disease in the United States, or they may not consider referring patients who are not in what they think of as an at-risk population. While most cases have been in men who have sex with men, not all are. For example, health officials in Indiana have reported that approx 20 percent of the state’s cases have been with women, and two infections in the United States has been identified in children.
Financial constraints, stigma, and lack of insurance or transportation to testing sites may also be barriers that keep some people with symptoms from seeking testing.
The US Food and Drug Administration says monkeypox should only be diagnosed by cleaning lesions, but a study published in June of researchers in Spain point to other possible ways to test for the virus. They detected monkeypox virus DNA in both saliva and semen samples from 12 patients with a confirmed infection.
The idea is already being pursued by Flow Health, a California company that has offered Covid-19 testing. The company is working on a monkeypox test that requires a person to spit into a plastic tube. Then, laboratory workers perform a PCR test, extracting and amplifying viral DNA from the sample.
CEO Alex Meshkin says a saliva-based test could have advantages; for example, it could enable screening of pre-symptomatic cases, something that has been crucial for Covid-19 testing. It could also be done at a pharmacy, mass testing site or even at home, to avoid the possible embarrassment of seeing a doctor. “Relying on a lesion graft that’s painful and invasive and can only really be done in a clinic is inherently going to have a pretty low demand because of the roadblocks to traditional health care,” says Meshkin.
But in a security notice issued on July 15 The FDA warned that testing samples not taken from a lesion can lead to false results. The agency noted that it is not aware of clinical data supporting the use of other sample types, such as blood or saliva.
Rivers says that developing other modalities so that testing can reach as many people as possible should be a research priority: “It’s important to determine whether testing oral fluids, for example, is as accurate as swabbing of lesions.”