Since May 17, when the first case related to a new outbreak was detected on American shores, the United States has identified some 110 cases of monkeypox, a disease caused by a virus similar to smallpox. In contrast, Britain has reported five times as many cases, despite having a population about 20 percent the size. One explanation for this discrepancy could be the relatively larger volume of travel between Britain and countries in which monkeypox is endemic — mainly in western and central Africa. But we strongly suspect another explanation, as well: Britain is doing a far better job of testing than the United States.
Does that story sound familiar? Throughout much of the coronavirus pandemic, the United States has relied on data from Britain to provide insights into infections that are within our borders. Britain has detected and described new variants faster, for example, and it continuously tests a representative sample of the population to estimate coronavirus transmission rates in communities. Nothing similar is supported by the Centers for Disease Control and Prevention, leaving local officials — in the era of at-home tests — largely guessing at the true prevalence rate (or reliant on the work of university researchers).
Now the United States, once again, appears to be responding to a new health threat with an underpowered testing response.
In the case of the coronavirus, recall that testing was delayed at first because the CDC had trouble producing a polymerase chain reaction (PCR) test kit; the problem was then compounded by shortages of swabs and other testing components. None of this is an issue with monkeypox testing. The PCR test already exists, there are no shortages of test components, and at least 74 state, federal, local and veterinary labs in the United States — those that participate in the Laboratory Response Network — are approved to perform this test; they have a capacity of up to 7,000 tests per week. (Technically, the CDC considers a positive PCR test from one of these labs a “preliminary” diagnosis, since the test identifies a family of viruses, not monkeypox itself; confirmatory testing can only be performed at a CDC facility. But the initial testing is sufficiently accurate to let doctors initiate treatment because monkeypox is the only disease from the family currently circulating.)
The problem for monkeypox testing right now is not capacity but access. For most disease testing, clinics and hospital-based medical practices have routine systems in place for ordering, transporting and receiving results from either the hospital or a contracted commercial lab. Getting a test at a facility in the Laboratory Response Network, in contrast, takes considerable work: It can involve contacting a local health department for approval, negotiating a lab’s unique electronic system and arranging transportation of the sample. Even clinicians deeply experienced with infectious diseases tell us that they’ve spent hours navigating the system. The logistical challenges make it less likely that primary-care doctors will request tests for patients with ambiguous symptoms.
Very early in the onset of a new outbreak of a rare disease, it is important that testing be conducted by specialized public health labs staffed by people trained to identify unusual pathogens; indeed, that’s why this network of facilities exists. But as an unusual virus begins spreading broadly throughout the community, testing needs to be quickly decentralized and integrated into the systems that health-care providers regularly use. Every aspect of outbreak response — supporting the isolation and care of patients, directing medicines to those who may have been exposed, and identifying and publicizing the extent of the problem — relies on rapid diagnosis.
We know that monkeypox has gotten ahead of our testing because most monkeypox cases in the United States have not been linked to known infected contacts. If a patient doesn’t know who infected them, that means there is at least one person in the community who is spreading infection to others without knowing it.
Skin lesions are a characteristic of this disease, but they can sometimes look innocuous, so it is very easy for a doctor to misdiagnose the patient, sending them home with treatments for a different infection (which will do nothing). The CDC recently reported that it is taking, on average, 11 days for patients to be diagnosed after they first spot a rash on their body — possibly a sign that patients are bouncing among multiple health providers. Easily accessible tests, combined with alerting doctors to the many different forms monkeypox lesions take, will make it far less likely that such cases will slip through the net. (Of course, delayed diagnoses mean more time for a patient to spread the disease.)
Infections so far have been concentrated among men who have sex with men; as a result, clinics specializing in sexual health are where most patients are being diagnosed right now. Providers in these clinics are more likely to consider monkeypox as a diagnosis and can grow used to working with specialized lab to do testing. But there is no biological reason for the current pattern of patients to hold. Making tests more easily available makes it more likely that nonspecialist doctors will identify monkeypox when patients present with its symptoms.
The CDC should work with some of the same commercial and hospital labs that were authorized early on to offer coronavirus testing to perform preliminary monkeypox testing. An initial step could be to give these labs access to the same test kits that are being used by the Laboratory Response Network. After that, companies and hospitals could be encouraged — as with the coronavirus — to develop their own tests. (The CDC will have to provide access to specimens needed to validate these tests.) We also need to develop other methods of testing beyond PCR, including point-of-care antigen tests, to give health-care providers maximum flexibility and to promote early isolation of infected patients.
As the new tests roll out, the CDC’s new forecasting center should produce more timely and comprehensive reports about the current status and dynamics of the outbreak — along the lines of what Britain’s Health Security Agency is publishing. Better information will encourage doctors to do more testing; in a virtuous circle, more testing will offer a clearer picture of the disease’s trajectory — while also helping to stop transmission.
Reports that the CDC and the White House are considering expanding testing for monkeypox are a welcome development, but it isn’t not happening fast enough. The window to contain this virus — and prevent it from causing more severe disease if and when it reaches more vulnerable patients than it has so far — is closing rapidly.