Cruel and deadly in equal measure, Ebola has killed nearly 5,000 people in west Africa - most of them, like Mr Cardoso's mother, dying without the benefit of a loved one to comfort them in their dreadful final hours.
But for him there is one consolation: the knowledge that while Ebola may have killed his mother, she in turn may have stopped it killing thousands or even millions of other Nigerians.
Dr Stella Adadevoh, as his mother was known professionally, was not a virology or public-health expert, simply a duty consultant at the First Consultant Hospital, a private clinic in Lagos. It was her sharp-eyed diagnosis, however, that identified Nigeria's first case of the virus - a 40-year-old civil servant called Patrick Sawyer, who flew in to Lagos from Ebola-devastated Liberia in July.
Unfortunately, Nigeria's "Patient Zero", as he is now referred to, was also suffering from acute "Ebola denial" syndrome. His sister in Liberia had died of the virus just two weeks before, and he knew that he too was a likely carrier. Yet in defiance of all common sense, he had boarded a flight to Nigeria, insisting he simply had a bad case of malaria even when he collapsed on arrival at Lagos airport.
It was Dr Adadevoh, 57, who first suspected he was lying - and, crucially, then stood her ground when he began screaming to be let out of hospital and threatening staff. At one point, he had to be physically restrained after pulling out his medical drips and splashing blood around his room.
Her courage had a high price. On August 19, nearly a month after Mr Sawyer's death, she too died - one of eight people he passed the virus on to directly. Were it not for her quick thinking, however, the current Ebola outbreak would almost certainly be far worse than it is. Nigeria, with 170 million people, has nearly 10 times the population of the other infected nations of Liberia, Sierra Leone and Guinea. And Lagos, a chaotic megacity of 17 million people, would have been a perfect petri dish for the virus to start spreading in. Had Mr Sawyer been allowed to leave his hospital room - let alone boarded a flight to a business conference in another Nigerian city, as he had intended - the consequences could have been catastrophic.
This weekend, health officials are trying to avert a similar disaster in Mali, after discovering that a two-year-old girl who was the country's first victim had travelled by bus more than 600 miles from Guinea, potentially infecting hundreds of other travellers.
Once again, it demonstrates the difference a vigilant medic can make - although so far Dr Adadevoh's extraordinary bravery has attracted little attention in the outside world. She did, however, receive an implicit accolade last week when the World Health Organisation (WHO) declared that Nigeria was Ebola-free again, with no new cases in the past six weeks. While credit also went to officials in Lagos who tracked down and quarantined hundreds of Mr Sawyer's fellow airline passengers, had it not been for Dr Adadevoh's early warning to the health ministry, an already difficult task would have been far harder.
As Rui Gama Vaz, a WHO spokesman, put it: "This is a spectacular success story. It shows that Ebola can be contained."
Such compliments are rare for Nigeria, where stories of sacrifice in the line of duty are vastly outweighed by those of corruption and incompetence. It is in stark contrast to the criticism that the government received for its bungled response to the kidnapping of more than 200 schoolgirls by the Boko Haram Islamist group in April.
But as ever in Nigeria, things worked out as much by accident as design. If it had been business as usual in Lagos, Dr Adadevoh would never have treated Mr Sawyer. When medics first picked him up from Lagos airport, the city's doctors were in the middle of a strike, meaning that medical services were even worse than normal. However, that proved to be a blessing in disguise. Rather than being taken to a public hospital, where he could have spent hours or even days waiting for treatment - potentially infecting hundreds of other patients and medics - he ended up at Dr Adadevoh's privately run clinic, which happened to be near the airport.
"My mum first saw him on her rounds the next day, at which point nobody had yet sussed him out - he was still being treated for malaria," says Mr Cardoso. "But she realised immediately that something was very wrong. She said it was as if blood was oozing right beneath his skin. She asked where he'd come from, the staff said 'Liberia', and straight away it clicked. Ebola. But I can understand why the others didn't realise: they'd never had Ebola in Nigeria before. One of the nurses had already given him a full body bath, so she died after getting a massive dose."
Had Dr Adadevoh been in Britain, where she worked at Hammersmith Hospital in the early 1990s, this would probably have been where her involvement ended. Officials would have swung into action, she would have been thanked for her efforts, and told the matter was now in expert hands. But this was Nigeria, and there were no experts. Instead, she spent the next few days learning on the job, hammering out a treatment protocol from scratch, trying to stop fellow staff panicking, and facing down threats from Mr Sawyer.
"When she and another doctor told him that he would have to be tested for Ebola, which would take two or three days, he flipped out," says Mr Cardoso. "He called the Liberian ambassador to Nigeria, who said they were going to sue the hospital for detaining him, that he was a VIP and had to go to this important conference.
"He was even trying to infect people intentionally, removing his drip. One doctor told me that blood was dripping from him like a tap, and that he tried to urinate all over the room."
Faced with such threats, it would have been all too easy for the medics to back down. Sticking up for the rules against well-connected functionaries is not always good for one's job prospects in Nigeria.
Dr Adadevoh, who is from a prominent Nigerian family - her son was educated at Rugby School in Warwickshire - refused to be intimidated. But that was no protection against the virus. While her family insists she always observed strict safety procedures, within three weeks of Mr Sawyer's death, an ambulance was taking Dr Adadevoh to Lagos's new Ebola ward - a "wretched place", her son says, set up in a disused TB clinic.
Mr Cardoso, an only child, and his father visited the ward every day, meeting a WHO Ebola specialist who would step out of his protective hazmat suit and give them an update. The father and son were also monitoring their own medical conditions closely, having been told that they too might have caught the virus from Dr Adadevoh.
"It was just an awful period," says Mr Cardoso. "Every morning we were waking up and checking our temperature, and little things like a sore throat or diarrhoea would make you panic."
Mr Cardoso did his best to rally his mother, speaking to her via mobile phone, and pleading with her to drink the eight litres of rehydration fluid that the doctors prescribed for her every day. On her fifth day in the clinic - Mr Cardoso's birthday - she seemed to rally. "The doctor said he thought she might be through the worst of it," he said. "But the next day, when we came in feeling the most optimistic we had been, they told us to prepare for the worst. My dad and I were just crushed."
Not surprisingly, Mr Cardoso holds Mr Sawyer partly responsible for his mother's death. "It was an irresponsible and wicked thing to do, to come to another country and infect other people," he says.
But the pain he feels about that has been offset by the endless plaudits for his mother in Nigeria's newspapers, which have hailed her as a national heroine. "The tributes make me proud because she deserves it. In somewhere like Lagos, Ebola could have been a nightmare."
Mr Cardoso - a prominent entrepreneur who has set up an Uber-style taxi app in Lagos - is now planning to honour his mother by founding a charitable health trust in her name.
However, in what some say is a typical example of old-school Nigerian bureaucracy, calls for her to be given a national award have so far gone unheeded. In September, the Nigerian government published its 2014 National Honours award list - mostly a bland roll-call of public worthies - but said that she could not be among them because such awards are never given posthumously.
However, universities, churches and even the country's 'Nollywood' film industry are already paying tribute to her with everything from honorary degrees to buildings named after her. A street vendor near Mr Cardoso's house even stocks CDs of songs and poems made in her honour. It is proof, perhaps, that whatever indifference the government has shown, ordinary Nigerians have already made up their mind.
"People are inspired by her story," says Mr Cardoso. "And for me, that is particularly good, because it is a Nigerian story."
* For more information on the health trust for Dr Stella Adadevoh, visit drasatrust.org
