Nine-year-old Tristan Ang was healthy in his fourth year when he became ill a month ago, first with what appeared to be a mild summer bug, then with more disturbing symptoms: confusion, forgetfulness, bad headache.
Six days later, he died in the intensive care unit of a hospital located near his home in Milpitas. The doctors explained to their parents that the cause was a brain infection caused by the virus most commonly associated with the common cold. In the case of Tristan, for reasons that no one understands, it was fatal.
"I do not know why it happened to him. It was just this extraordinary accident, "said Mark Ang, Tristan's father. "Maybe God really wanted it up there."
Just before his death on June 28, Tristan was tested positive for the adenovirus, which is actually a family of viruses made up of more than 50 strains. The strain infected with Tristan is unclear.
Adenoviruses usually cause symptoms such as sore throat, runny nose and cough. It is thought that up to 10% of colds are caused by adenoviruses. They are the most common cause of conjunctivitis, also called pink eye. Some strains cause diarrhea.
Almost all children were infected with at least one adenovirus strain at Tristan age. The infection immunizes immunity against this strain of the virus, but since there are so many other strains, adenoviruses can get sick many times.
Some strains are known to cause much more serious diseases, including pneumonia and, rarely, meningitis or encephalitis – infections of the brain or spinal cord. But fatal cases almost always affect people whose immune systems are weakened – for example, organ transplant recipients – and even in these cases, it is unusual to die of an adenovirus.
"These are normal childhood infections. It's almost shocking to see someone die of this disease, "said Dr. Yvonne Maldonado, head of pediatric infectious diseases at Stanford. Maldonado did not know the details of Tristan's case.
It is not known how many people die of adenovirus each year, because the virus can not always be found in the blood, tissues or cerebrospinal fluid. Last year, at least six children died of adenovirus infection during an outbreak in a New Jersey rehab center. The children all had a compromised immune system and had been infected with an adenovirus strain, one of the most serious.
Adenoviruses are contagious, but they usually require close contact to be passed from person to person. Outbreaks can occur in environments such as daycares, dormitories and military barracks. A major outbreak occurred in 1997 at a US Navy training center – 541 young healthy adults were infected at the time, most cases of adenovirus-associated pneumonia.
How to help the boy's family
A friend has opened a GoFundMe account for Tristan's family to cover funeral and other expenses: www.gofundme.com/f/in-loving-memory-of-tristan-michael-o-ang
In fact, as early as the 1950s, adenoviruses were the cause of epidemics among the military. A vaccine for two particularly virulent strains was developed in the early 1970s and, for several decades, the military routinely entrusted it to recruits. But the only manufacturer of the vaccine stopped making it in the mid-1990s and the military ended its vaccination program. A small amount of vaccine still exists, but it is only available for the military.
And generally, people should not think about being vaccinated against adenoviruses because they rarely cause serious diseases, said experts in infectious diseases.
"We can not really vaccinate the entire population against an extremely rare disease – the cause of a serious disease," said Dr. Charles Chiu, director of the UCSF-Abbott Viral Diagnostics and Discovery Center.
Chiu said that the unusual death of a healthy child from an adenovirus should result in a public health survey. Officials can monitor people in close contact with the child for signs of illness, especially if the strain involved is particularly virulent. Mark Ang said that no one else in the family was sick.
The Santa Clara County Department of Public Health would not say whether there are any cases of adenovirus currently under investigation or commenting on Tristan's death. A spokesman said the county was reviewing all cases of meningitis or encephalitis; Last year, there were 53 such cases caused by various infectious agents, including viruses and bacteria.
Chiu – who is not involved in Tristan's care – said there are several reasons why a normally domesticated virus can kill an apparently healthy child. A child may have an underlying immune disorder that has not been detected before. It could be infected with another pathogen that makes it vulnerable to serious diseases caused by adenovirus.
Or it could be infected by a virus strain that has mutated, making it more aggressive. This is part of the reason why a public health survey is important, Chiu said.
A spontaneous mutation of the virus is not probable, but is not unknown. In 2012, Chiu investigated an outbreak of adenovirus in laboratory monkeys at UC Davis, in which the virus suddenly developed the transmission capacity between animals and humans. A veterinarian and another person were infected with the new strain, which happily caused mild illness in humans. He killed about 80% of infected monkeys, however.
There is no specific treatment for adenovirus infection, even the most serious strains. An antiviral drug exists, but it is not clear if it helps, and it has serious side effects, said Maldonado.
People can prevent the spread of the disease by regularly washing their hands and avoiding contact with other people recognized as such, said Dr. Darvin Scott Smith, infectious disease specialist at Kaiser Permanente Redwood City. Anyone with symptoms such as cough, fever, runny nose, sore throat and itchy, burning eyes should stay at home instead of going to work or to school.
But in most cases, adenoviruses will circulate and there is not much that can stop them.
"I do not know what matters, other than washing your hands. And that goes a long way, but there are limits to what you can do, "said Smith.
Tristan's parents, who are both nurses, repeated the events that led to his death in recent weeks, trying to understand what had happened and if they could have done anything else. There was none, said Mark Ang. He knows it, but he can not help asking the question.
He and his wife, Belle Ang, tried for 14 years to become pregnant before Tristan's birth. They ended up having two more kids, but it's Tristan who's been doing their whole life, said Ang. He was competitive in taekwondo nationally – he was scheduled to participate in a tournament in Minnesota this month – and his training defined the family's schedule.
But he was also the heart of the family emotionally, said Ang.
"He would kiss you out of nowhere, kiss you, tell you that he loved you," Ang said. "He was a child so good hearted. I know that he would have helped a ton of people.
"I hope that other people will be able to draw something from what has happened to us, even if it's just, love your children. Keep them close, because you can lose them so fast.
Erin Allday is a writer at the San Francisco Chronicle. Email: firstname.lastname@example.org