DAKAR, SENEGAL (NYTIMES) - In the northern Nigerian city of Kano, some people say they now get four or five death notices on their phones each day: A colleague has died. A friend's aunt. A former classmate.

The gravediggers of the city, one of the biggest in West Africa, say they are working overtime. And so many doctors and nurses have been infected with the coronavirus that few hospitals are now accepting patients.

Officially, Kano had reported 753 cases and 33 deaths attributed to the virus as of Friday (May 15). But in reality, the metropolis is experiencing a major, unchecked outbreak, according to doctors and public health experts. It could be one of the continent's worst.

The coronavirus has been slower to take hold in Africa than on other continents, according to the numbers released daily by the World Health Organisation.

But blazing hot spots are beginning to emerge. Kano is only one of several places in Africa where a relatively low official case count bears no resemblance to what health workers and residents say they are seeing on the ground.

In Somalia's capital, Mogadishu, officials say that burials have tripled. In Tanzania, after cases suddenly rose and the US Embassy issued a health alert, the Tanzanian government abruptly stopped releasing its data.

Kano's state government, until recently, claimed a spate of unusual deaths was caused not by the coronavirus but by hypertension, diabetes, meningitis or acute malaria. There is little social distancing, and few people are being tested.

"The leadership is in denial," said Usman Yusuf, a haematology-oncology professor and the former head of Nigeria's national health insurance agency. "It's almost like saying there is no Covid in New York." He said he thought a significant portion of the population was probably infected in Kano, a city with an estimated 5 million people (although there has been no census since 2006).

Although they have now acknowledged they have a problem with Covid-19, the disease caused by the coronavirus, authorities in Kano spent precious weeks denying it, despite the surge in what Abdullahi Umar Ganduje, the state governor, called "mysterious deaths." "So far, there's been nothing to suggest that they are linked with Covid-19," Ganduje posted on Twitter on April 27, when, according to doctors in Kano's hospitals, the city was already firmly in the grip of a serious coronavirus outbreak.

There was nothing mysterious about what doctors said they were seeing at Aminu Kano Teaching Hospital, the city's main public hospital. Starting well before Kano's first case was reported April 11, the hospital saw a steady stream of older patients with fevers, coughs, difficulty breathing and low oxygen saturation levels, many of them with underlying health conditions.

Doctors at the hospital called the government's response team. Sometimes it took 24 hours to get a call back. Sometimes, the team refused to test or isolate patients, saying they did not qualify because they had not travelled recently.

About 60 per cent to 70 per cent of the elderly patients who went to the hospital and later died had arrived with full symptoms of Covid-19, said a doctor in the medical department, who, along with another doctor, spoke on condition of anonymity because they feared retribution.

One doctor said the department's death registers for April showed far more patients had died than normal. Most patients were sent home, he said, and the hospital's staff members often would hear later that they had died.

With no personal protective equipment except surgical masks, the doctors said they knew the risks they were running in treating these patients. They said that they begged the hospital management for N95 masks, face shields, gloves and aprons, but that none came. They asked for an isolation centre at the hospital, scared that patients with other ailments would be infected. They wanted the facilities fumigated. Nothing happened.

And then it was too late. The doctors began to get sick.

"All of us were exposed," said the other doctor. "Ultimately, what we feared has happened." Twenty of the 91 doctors in the hospital's medical department tested positive, the doctors said. Overall in Kano, 42 doctors and 28 nurses have tested positive, and one doctor has died, according to Dr Sanusi Bala, chair of the Kano branch of the Nigerian Medical Association. Laboratory technicians in what was then Kano's only testing laboratory got sick, too, and it closed for several days. The city's health system, already extremely limited, was crippled.

Nigeria, a country of about 200 million people, says it can in theory do 2,500 tests a day, and Kano up to 500. But it has been conducting far fewer tests, typically 1,000 to 1,200 daily. Test results in Kano can take two weeks. Doctors awaiting their test results cannot go to work. People in quarantine cannot leave.

"If I say thousands of people are dying from Covid, I don't think I exaggerated the figure," said the doctor who begged for PPE. "So many people are dying without being tested, without even going to the hospital." While the government loosened lockdowns May 4 in the capital, Abuja, and biggest city, Lagos, it extended the one in Kano. But few people observe it. The many funerals are well attended, residents said.

Many in the city think the coronavirus is a hoax, perhaps because public messaging about it is mostly in English, which most Kano residents do not speak, health experts said.

Others believe that a Covid-19 diagnosis is a death sentence, the experts said, and do not want their neighbours to think they are infected. So they avoid being tested and try to behave as if all is normal.

By late April, the Kano state government finally admitted there was a Covid-19 problem and asked the federal government for help. Sarkinfada, the medical microbiologist, said that the federal government focused its efforts on increasing Kano's testing capacity, and that test results were now coming in sooner.

"The Kano situation has seen us through deception, denial, defiance, denunciation, disagreement and finally acceptance and action to control the disaster," said Oyewale Tomori, a virologist who leads a Nigerian government committee on Covid-19.

Kano's location, population and connectivity to the rest of the region mean the consequences of an uncontrolled outbreak could be severe.

Already there are reports of hundreds more people dying "mysterious deaths" in Nigeria's northern states of Jigawa, Yobe, Sokoto and Katsina, including three emirs, or traditional Muslim rulers, and a former health minister.

"If Kano falls, the whole of northern Nigeria falls. The whole of Nigeria falls," Yusuf said. "It spreads into the whole of West Africa and the whole of Africa."