A new study examining a previous outbreak of Ebola in Uganda offers the first clues as to why children appear to be better than adults at fighting off the Ebola virus.
Earlier research from the Uganda outbreak, which took place from 2000-2001, and a more recent study from the current outbreak analyzing data from a Sierra Leone hospital, have both suggested that children are more likely to survive the virus than adults. Now, a study recently published in the medical journal Emerging Infectious Diseases is exploring why that might be the case.
A health official dressed in protective gear examines children suffering from Ebola at Makeni Arab Holding Centre in Makeni, Sierra Leone. (AP Photo/Tanya Bindra)
The study was published in October and focuses on the Uganda outbreak, which resulted in 425 Ebola cases, 145 of which were patients aged 21 or under. Until the 2014 outbreak, this was the largest proportion of pediatric patients ever seen in an Ebola epidemic. Of the lab-confirmed cases in this episode, 53 percent of the general population died, while only 40 percent of children and teens died.
There are a number of contributing factors that may help explain the disparity in survival rates, according to Dr. Anita McElroy, M.D., Ph.D., the study's lead author and an assistant professor in the Pediatrics department at Emory University School of Medicine.
McElroy’s work for this study, conducted while she was a guest researcher with the Centers for Disease Control and Prevention’s viral special pathogens branch, focused on biomarkers that could explain why children and adults had different immune responses. One theory, she told The Huffington Post, is that children may simply have better immune responses than adults.
McElroy examined blood serum samples of 45 children and 50 adults from the Uganda outbreak and found some fundamental differences in the immune systems of those under age 21. For one thing, children -- especially children who survived -- were more likely than adults to have elevated levels of a protein called RANTE. McElroy explained that RANTE is a signaling molecule that helps immune cells talk to each other. It also helps T-Cells, which play a big role in fighting the Ebola virus, do their job properly.
“We didn’t see that in adults,” said McElroy. "That led us to think that perhaps kids who survive had better immune responses than their adult counterparts, and that might explain why kids survive at a higher rate than adults do."
Another possible reason for children's higher survival rates is that children are less likely to have poor health behaviors compared to adults. They are less likely to smoke or to suffer from hypertension or other diseases that could weaken the body's ability to fight against Ebola.
Children are also less likely than adults to be the primary caretaker of someone who is sick with Ebola. This is an important distinction, said McElroy, because home caretakers or health workers in hospitals are more likely to come into direct contact with fluids like vomit, diarrhea or blood from an Ebola patient, whereas children might only be exposed to, say, an object covered in that fluid. That introduces smaller amounts of the virus into children’s bodies, while adults might start off incubating larger amounts.
McElroy's team had access to age and survival rate information for 55 pediatric patients with lab-confirmed Ebola from the Uganda outbreak. Children aged five and under died in 76.9 percent of cases, children aged six to 15 had a 37.5 percent fatality rate, and children aged 16-21 had a 41.6 percent fatality rate. In contrast, the 161 adult patients with lab-confirmed Ebola had a fatality rate of 56.5 percent.
McElroy said she wasn’t surprised that infants were more likely to die if they contracted Ebola.
“This is not super surprising, because the immune system takes some time to mature,” said McElroy. “But once you get into that school-aged group, that’s when you saw all the protection from Ebola.”
A child suffering from the Ebola virus receives treatment at Makeni Arab Holding Centre in Makeni, Sierra Leone. (AP Photo/Tanya Bindra)
On the other hand, the study also found that children had some physiological differences that put them at a disadvantage compared to adults. Still, these results were meaningful because they pointed to differences in the way that immature and mature bodies handle the virus.
McElroy's team found that children were more likely than adults to have “endothelial dysfunction," which occurs when the cells that line blood vessels break down, leaking blood vessel fluids into tissue. This problem was especially prominent among children who did not survive, which leads McElroy to believe that children might be better treated with a class of medicines called statins. Statins lower the cholesterol level in blood, but they also have a side effect of strengthening the cells in blood vessels.
Ebola isn’t unique in its tendency to induce different symptoms in people of different ages, the study noted. For example, tuberculosis is often mild in school-aged children and teens, but can cause more serious infection among very young children and can progress to lung disease in adults.
It’s unclear how applicable McElroy’s findings are to the current Ebola crisis or to future outbreaks. The patients she studied had contracted the Sudan strain of the Ebola virus, which typically has a 60-65 percent mortality rate and spreads more easily than others, while the current outbreak in West Africa is infecting people with the Zaire strain, which has mortality rates of up to 85-90 percent.
Before this study, the only age-related analysis that had been published on the current outbreak was based on data from May 2014, gathered from a hospital in Sierra Leone. The data, published in the New England Journal of Medicine, found that patients aged 21 and under were less likely to die than patients over 45 years of age -- a difference of a 57 percent fatality rate versus 94 percent.
Physical survival is not the only component of healing, according to the well-known missionary doctor Kent Brantly, who treated two pediatric patients in Liberia before contracting Ebola himself. Brantly, who was eventually cured of the virus, told HuffPost last week that the children on the Ebola ward where he worked were traumatized by their surroundings.
The doctor told the story of one 14-year-old patient, who would remove himself from the room, at great personal effort, to avoid the dead and dying.
"He’d go outside the unit -- still in a high-risk zone -- and sit on a stump or play with a soccer ball so he would not have to witness what we were doing with that dead body. That’s traumatizing. That’s tragic," said Brantly.
“It’s also traumatic for the staff to know that the horror that we are seeing firsthand, that there’s a young child that is having to face that reality right alongside us," he added.
While there are few studies on how the Ebola epidemic has affected patients and their family members psychologically, research on the psychological effects of HIV shows that children who live through parents' HIV illnesses are at risk for depression and post-traumatic stress disorder.
Caroline Kuo, a public health professor specializing in community-based HIV intervention at Brown University, told HuffPost in an interview earlier this month that both children and adults are susceptible to psychological distress after surviving a devastating illness like HIV or living through a loved one's illness. She says Ebola may be a similar case.
Stigma plays a large role in this distress. Kuo's research shows that it's important not to automatically "pathologize" families -- treat them as unhealthy or abnormal -- just because they've been affected by a disease.
"When there is a very stigmatizing element that appears, such as HIV and Ebola, immediately people want to ask: How do we fix it and what’s wrong?" said Kuo. "But the starting point should really be [to ask] about the inner sources of resilience that individuals have, and how we can identify ways to support them."
"At-risk children have talked to us about their inner source of confidence and pride," Kuo continued. "We're learning that trying to tap into this confidence, identifying children's hopes for the future and trying to support those future hopes and goals is really critical for their resilience."
Promise Cooper, 16, fills a bottle with a chlorine solution with the help of Kanyean Molton Farley, a community activist who visits Promise and her two brothers, Emmanuel Junior, 11, right, and Benson, 15, not pictured, on a daily basis at their St. Paul Bridge home in Monrovia, Liberia. The Cooper children are now orphans, having lost their mother Princess in July, and their father Emmanuel in August. Their 5-month-old baby brother, Success, also succumbed to the virus in August. (AP Photo/Jerome Delay, File)