The man in his 20s came to the emergency department with blisters on his lips, hands and back. Doctors diagnosed him with monkeypox within a day.

Their certainty came to an end at that location. The patient did not have any of the symptoms of the disease. He didn't know how he became sick. He hadn't had sex with anyone for months, and hadn't touched anyone with pox, even though it's a symptom of the disease.

Scientists thought at the start of the outbreak that they knew when and how the monkeypox virus was spread, who was most vulnerable, and what the disease looked like. Many expectations have been upended by the 44,000 cases identified.

Patients with monkeypox have turned up with small bumps on their skin, not the large blisters usually associated with the disease. Some people felt pain when swallowing, urinating or emptying their bowels, even though they didn't have any visible disease.

Some of them had headaches or depression. Other people had infections of the heart muscle. Three of the six deaths have been linked to encephalitis.

The infectious disease physician at a clinic in Atlanta that serves people living with H.I.V. said they are seeing a wide range of presentations.

The monkeypox virus can be found in saliva, semen and other bodily fluids after a recovery. It is known that the virus can be spread through close contact, but it is also thought to be transmitted through sex.

The California patient had a virus in his throat but no respiratory symptoms and no pain. The case shows that the virus can be spread even by people who don't have any symptoms.

In a study published this month, anal samples from 200 men with no symptoms turned up 13 who were positive for monkeypox. Two of them had symptoms.

ImageA patient with monkeypox sores in a hospital in Lima, Peru.
A patient with monkeypox sores in a hospital in Lima, Peru.Credit...Ernesto Benavides/Agence France-Presse — Getty Images
A patient with monkeypox sores in a hospital in Lima, Peru.

Dr. Orkin is an infectious disease physician at Queen Mary University of London I think that it means that our model of how it's spread is wrong.

The C.D.C. said that people who don't have symptoms can't spread the disease. Scientists are still researching the possibility of asymptomatic transmission according to the agency.

A spokeswoman for the agency said in a statement to The New York Times that it was still unclear whether people without symptoms could spread the virus and that more research was needed.

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Monkeypox is what it is. The symptoms of monkeypox are not as severe as those ofpox. There was an outbreak in monkeys kept for research. Most of the people who have sex with men who have the virus are from Central and West Africa.

What does it do? The monkeypox virus can be spread by coughing or sneezing, or by touching items that have previously touched the rash, or by touching items that have not touched the rash. During and after birth, monkeypox can be transmitted from the mother to the fetus.

I'm afraid I might have a disease. I don't know what to do. You can't test for monkeypox if you only have flu symptoms. You can get a monkeypox test from an urgent care center or your primary care doctor. If you have to come in contact with other people for medical care, you should be isolated at home.

I live in the city. Is it possible to get the vaccine? Adult men who have sex with men and have had multiple sexual partners in the last 14 days are eligible for a vaccine in New York City. People with conditions that weaken the immune system or have a history of allergies are encouraged to get the vaccine. There is a website that people can use to book an appointment.

Many scientists were surprised when the first dozen cases of monkeypox appeared in Europe. That shouldn't have happened.

Many young men with genital ulcers were documented by Nigerian researchers. The patients identified as heterosexual were from Nigeria.

The first cases in Nigeria in 40 years were reported by the World Health Organization.

The strange symptoms of the patients were not noticed. Dr. Dimie Ogoina said that the paper wouldn't be discussed if the cases hadn't happened.

He said that the disease has been around for more than 50 years and that it has been mostly restricted to Africa.

The largest study of monkeypox was put together by Dr. Orkin in May. The physicians from 16 countries gave information about the cases they were seeing.

As the disease came into sharper focus, they changed the reporting forms to include the possibility of a single pox, a sore throat, and medical problems.

The analysis of over 500 patients was published in The New England Journal of Medicine. The findings should change the case definitions that doctors use when they diagnose patients.

ImageDr. Chloe Orkin, an infectious disease physician at Queen Mary University of London. “I’ve got a loud voice,” she said, “and I’m still finding it difficult to get a response.”
Dr. Chloe Orkin, an infectious disease physician at Queen Mary University of London. “I’ve got a loud voice,” she said, “and I’m still finding it difficult to get a response.”Credit...Suzie Howell for The New York Times
Dr. Chloe Orkin, an infectious disease physician at Queen Mary University of London. “I’ve got a loud voice,” she said, “and I’m still finding it difficult to get a response.”

The European Centers for Disease Control and Britain's Health Security Agency both responded to the same question. Some of the new symptoms were added to the definition by Britain. Dr. Orkin presented her findings.

In an interview in July, Dr. Orkin said that during a Pandemic, public health agencies are the experts and doctors are educated on the disease. The symptoms are seen by clinicians.

She thinks that consulting with clinicians in the field may have helped. She said that national health agencies have been slow to understand the symptoms of the disease.

A governing council member of the International AIDS Society, Dr. Orkin is also president of the Medical Women's Federation. She said that she was still finding it hard to get a response.

The senior members of the W.H.O inquired about the cases that she and her colleagues had described. The C.D.C. added rectal pain and bleeding to its guidance for clinicians on August 5.

The range and importance of pox in the mouth, eyes, and urethra are not described in the new definition. The agency said it was aware of Dr. Orkin's findings and had begun studies to better understand the range and importance of lesions.

In light of reports that the monkeypox virus can persist in semen for weeks, Britain recommended that men who have recovered from the disease use condoms for a year.

The C.D.C. said that they are working with their partners to find out if the virus is being spread through semen.

Britain has advised men to wear condoms for a short period of time. He said they don't know how long people can transmit. They should tell that clearly.

Old case definitions and guidance can have serious consequences for patients. The man was exposed to the virus on July 6. He developed a sore throat, head and body ache, painful urination, and bumps on his face, thigh, and elbow after two weeks.

His doctor didn't connect the symptoms on his first visit. She told him that he had an ingrown hair and that he needed to get a urinary tract infection.

Three days later, he returned. He was going to be tested for monkeypox this time. He had to push again to get the tecovirimat after he tested positive.

Mr. French said he was most frustrated by the lack of guidance on how to distinguish between a new pox and a pimple. He said that the question mark was ambiguous. It has been difficult.