May 24, 2017
São João Pequeno, Brazil – Two years of drought had been hard on Valdemar Braun and his three grown sons. They lived in the hilly, picturesque Brazilian village of São João Pequeno, and when the rains quit, the coffee would not grow. The farmers were forced to sell some of their cows.
Then at last the showers returned, and 2017 dawned full of promise for the plantations.
Valdemar had given each son two alqueires of land (almost 11 acres). In mid-January, one son helped another clear out forest to plant more coffee.
The portion of forest belonged to Edson Braun, who had recently divorced. He wanted to transfer the land to his ex-wife so that she could provide for their daughters. His brother, Virlei, agreed to help.
Virlei, 30, with pale blue eyes and a handsome face, had his own family to provide for: a wife and toddler son. On the day he went to help his brother, Virlei had already worked on the farm for 14 days straight. Never in his life had he been to a doctor for a health problem.
That day in the forest, relatives believe, a mosquito bit Virlei.
In just 10 days, he would die, doctors desperately trying to lower his fever by packing his abdomen in ice, his mother crying out, “God, don’t take my son. Don’t take my son.”
“Go back home and help raise my child,” Virlei told her. “I’ve already put myself in the hands of God.”
Brazil, hit hard by the Zika virus in 2015 and 2016, is once again in the throes of a devastating mosquito-borne disease.
The illness that killed Virlei and at least 263 other Brazilians so far is yellow fever, a virus that can cause victims to vomit blood, suffer liver damage, and even descend into organ failure and coma. In some of Brazil’s forests, the virus recurs every six or seven years.
The current outbreak is the nation’s worst on record; yellow fever deaths in the first four months of 2017 already exceeded all those from 1989 through 2008.
At the epicenter of this epidemic is a group of states that had just recovered from their worst droughts in 80 years. This intersection of drought and disease raises a complex and troubling question for scientists:
Is our changing climate contributing to flare-ups of infectious diseases?
“Yes, this is a factor that is present in our modeling,” says Márcia Chame, a researcher who has been examining the outbreak for the Oswaldo Cruz Foundation in Rio de Janeiro.
But climate alone cannot account for Brazil’s latest bout with yellow fever, according to Chame, coordinator of the foundation’s biodiversity research unit.
Other contributors include the clearing of forests for farms and plantations, an activity that brings humans into areas thick with mosquitoes; the grinding rural poverty that makes insect repellent a luxury for many villagers; and the reluctance of many Brazilians to receive the yellow fever vaccine.
Still, it is clear that the recent climate in the areas most affected by yellow fever — severe drought followed by rainfall — benefits the forest mosquitoes. Their eggs can survive dry weather in a state of suspended animation “for years and years,” according to Michael T. Osterholm, co-author of the new book, “Deadliest Enemy: Our War Against Killer Germs.”
When rains do come, they unleash several years’ worth of mosquito offspring. Whether the current outbreak is linked to climate change “is unclear,” Osterholm cautions. “It wouldn’t surprise me, but I don’t think we can say that.”
So far, yellow fever has been confined to rural, wooded areas, mostly in four states on Brazil’s eastern flank: Minas Gerais, Espírito Santo, São Paulo and Rio de Janeiro. But the virus has already spread much farther than in previous outbreaks, raising an unsettling possibility.
“If this thing takes off in the urban areas of Brazil, we’re in big trouble,” says Osterholm, who serves as director of the Center for Infectious Disease Research and Policy at the University of Minnesota.
Large cities, with their high densities of people and mosquitoes, can fuel an outbreak, just as dry tinder feeds a forest fire.
In late April, Brazilian authorities announced that the latest victim to die had lived just 35 miles from the city of Rio de Janeiro, population 6.3 million.
Experts say it is unlikely the U.S. will see a comparable outbreak of yellow fever, in part because air conditioning and window screens are commonplace, allowing us to keep mosquitoes out of our homes in hot weather. Still, any cases — even those brought here by travelers — could prove unnerving, especially since the currently-approved vaccine is in short supply.
Sanofi Pasteur, the sole manufacturer and supplier of the yellow fever vaccine to the U.S., is experiencing production delays as it moves to a new facility. The vaccine approved for the U.S. is likely to be unavailable from June 2017 until mid-2018, though the company says it has received FDA permission to distribute a different vaccine, unlicensed here, but used in 70 other countries.
The U.S. has not experienced an outbreak of yellow fever in more than a century; the 1905 epidemic in New Orleans that killed more than 430 people was the last. Yet the past 20 years have seen the appearance or reappearance of several other mosquito-borne diseases in this country.
In 1999, it was West Nile virus, which arrived in the U.S. in New York and has since spread through almost the entire country.
In 2001, it was dengue fever, thought to have been eliminated from the U.S. 30 years earlier. Hawaii, Texas and Florida have all reported outbreaks of dengue, a virus that produces flu-like symptoms but can lead to severe illness and death.
Last year, it was the Zika virus making its first appearance in the U.S. in South Florida and Brownsville, Texas, a port city on the Mexican border.
Osterholm notes one parallel between Brazil’s latest bout with yellow fever and the appearance of West Nile virus in New York. “In 1999, when West Nile virus broke in the U.S., lack of rainfall favored the mosquito,” he says.
There is another parallel.
With West Nile, animals fell sick before humans did. Tracey McNamara, then-head pathologist at the Bronx Zoo, noticed crows dropping dead in and around the zoo. Soon afterward, doctors began seeing patients with symptoms resembling encephalitis, including fever, dizziness and fatigue.
In Brazil, monkeys served as sentinels for the latest outbreak of yellow fever. In April 2016 — eight months before any people became sick — a single monkey was found dead on a farm in Montes Claros, about 530 miles north of Rio de Janeiro.
Even in areas where monkeys are plentiful, it is unusual to find one dead. Their bodies generally decompose quickly, or are consumed by scavengers.
In this case, health officials came to Montes Claros to collect the monkey’s remains for testing. Waldney P. Martins, a professor at Universidade Estadual de Montes Claros who studies monkeys, says it took four months to determine the cause of death.
José Luis Machado, housekeeper for Fazenda Macacos, the “Farm of Monkeys,” was born just two miles away in the village of Itapina, which lies about 400 miles northeast of Rio de Janeiro.
He has been there so long, he says, that he feels like part of the forest, much like the howler monkeys he used to watch feasting on mango leaves. A group of eight to 10 monkeys were permanent residents. They clambered through the trees. Sometimes their shouts could be heard clear across the Rio Doce, or Sweet River, a mile away.
“This was full of monkeys,” Machado says, staring at a hollow of empty trees. Like many of the Brazilians interviewed for this story, he speaks through an interpreter.
“They were very happy,” he says. “They make the house happy too.”
But on this morning in early April, the house and forest are quiet.
The property’s owner found the first dead monkey on the last day of 2016. Soon after, Machado watched other monkeys fall ill.
“When they were already very sick,” he says, “they would fall down from the tree and die on the (forest) floor.”
About the same time Machado was watching the monkeys die in Itapina, University of Wisconsin-Madison researcher Karen Strier was discovering that a similar tragedy had already played out on a reserve 140 miles to the west.
In mid-January, the professor of anthropology arrived from Wisconsin to find an unnatural quiet in the reserve. In a place she has been coming to for more than 30 years, where she was accustomed to seeing hundreds of howler monkeys, she and her Brazilian colleagues saw fewer than a dozen.
“The forest was really, really different,” she says. “It was actually pretty terrifying.”
Back east in São João Pequeno, Valdemar Braun had also been wondering about the monkey population. Two dozen or so used to come right onto his covered porch to eat juicy guava.
“They have all disappeared,” he says.
Although he cannot remember precisely, he believes the monkeys vanished around the end of last year. Before his son Virlei grew ill and died.
The idea that climate and disease are related dates back at least 2,000 years to the Greek physician Hippocrates. He wrote:
“Whoever wishes to investigate medicine properly should proceed thus: in the first place to consider the seasons of the year and what effects each of them produces … Then the winds, the hot and the cold, especially such as are common to all countries, and then such as are peculiar to each locality.”
For some of the most serious diseases, including yellow fever, it is not so much the effect of climate on humans that matters; it is the effect on insects.
“There are some people that argue that global warming’s greatest threat may also be the smallest, and, of course what we’re thinking about are insect-borne diseases,” explains Jonathan Patz, director of the Global Health Institute at the University of Wisconsin-Madison.
“And we all know that insects are cold-blooded, unlike us, and when the temperature changes a little bit, their body temperature changes with it.”
Decades of research has established that Aedes aegypti, a species of mosquito that carries yellow fever, Zika, dengue and chikungunya, thrives in warmer climates.
The mosquitoes are more active, reproduce more frequently and enjoy a longer breeding season, though there’s a catch. If the climate becomes too hot and dry it can shorten their lifespan.
In general, warmer temperatures also lead to smaller mosquito offspring which require more blood meals. In other words, they bite more.
Mosquitoes that transmit West Nile virus show a similar sensitivity.
“Every degree above 70 degrees exponentially expands the mosquito’s ability to transmit West Nile virus,” says McNamara, the former Bronx Zoo official, now a professor of pathology at Western University of Health Sciences in Pomona, Calif.
“Forget the cockroach inheriting the Earth. It’s going to be the mosquito.”
Already, warmer temperatures have helped mosquitoes settle into new regions. For example, Aedes albopictus, another of the mosquitoes that carries the viral diseases dengue and chikungunya, “has undergone a dramatic global expansion facilitated by human activities,” according to the European Centre for Disease Prevention and Control.
Found originally in the tropical forests of Southeast Asia, Aedes albopictus, commonly known as the Asian tiger mosquito, has spread into Europe, the Middle East, Africa, and North and South America — largely in the last 30 years. The mosquito, first discovered in the United States in Houston in the mid-1980s, has since spread to 37 states, though not to Wisconsin.
Researchers believe the Asian tiger mosquito’s rapid advance has been fueled by international transport of old tires and bamboo, objects that retain water, making them ideal places for mosquitoes to lay eggs.
Once carried overseas, however, the mosquitoes are finding the warming climate to their liking. In a 2013 paper in the journal PLOS ONE, researchers said the Asian tiger mosquito “is poised to significantly expand its range in the northeastern United States in the next few decades primarily due to warming winter temperatures.”
Where the mosquitoes migrate, disease often follows.
In the summer of 2007, Europe experienced its first epidemic of chikungunya in northeastern Italy. In the years since, France and Croatia have experienced their own outbreaks. The disease, which causes fever and severe joint pain, had been found mostly in Africa, Asia and India.
In December 2013, chikungunya was detected for the first time in the Americas, on the Caribbean island of Saint Martin. Since then, the disease has been found in 45 countries or territories in the Americas, though it has rarely appeared in the U.S., according to the U.S. Centers for Disease Control and Prevention.
And mosquitoes aren’t the only bearers of disease that flourish in warmer climates.
Sand flies, which transmit the parasite that causes leishmaniasis, a skin disease, are also more active and take more blood meals in warmer temperatures.
Blacklegged ticks have prospered in the heat, aiding the northward expansion of Lyme Disease. Lyme cases in Canada have risen more than five-fold since 2009; Lyme cases in Wisconsin have doubled since 2000.
“The growing season’s longer. It’s great for ticks and not so great for human health, because if those ticks have another couple of weeks in which to find a host, then many more of them are likely to survive,” says Richard Ostfeld, senior disease ecologist at the Cary Institute of Ecosystem Studies and director of a study aimed at preventing tick-borne diseases.
In a 2005 paper in The New England Journal of Medicine, Harvard University tropical health expert Paul R. Epstein offered one example of how a change in climate can ripple through an ecosystem. Epstein described the arrival of a new disease with flu-like symptoms, carried by rodents and passed to humans:
“Six years of drought in the Southwest apparently reduced the populations of predators, and early heavy rainfall in 1993 produced a bounty of pinon nuts and grasshoppers for rodents to eat. The resulting legion of white-footed mice heralded the appearance of hantavirus in the Americas.”
Few scientists, if any, attribute the spread of these diseases to climate change alone.
Studies suggest that other likely factors include global reductions in pesticide use and massive increases in waste plastics, such as bags, suitable for breeding by mosquitoes. In a larger sense, the growth and spread of the world’s population into rural areas is undoubtedly bringing more humans onto the turf of mosquitoes, ticks and other parasites and insects.
In Brazil, some point to another possible culprit for the current bout of yellow fever, though the theory is controversial.
“(It is) due to the environmental disaster which happened in Mariana,” says Antônio Thadeu Tardin Giuberti, the health secretary for the municipality of Colatina.
He refers to the Nov. 5, 2015, dam failure at a mine in Mariana, 250 miles north of Rio de Janeiro. When the dam failed, a torrent of iron ore waste flooded the countryside, killing 19 people and contaminating the Doce River, the same river that flows past the villages where José Luis Machado watched the monkeys die and where Valdemar Braun lost his son.
While Giuberti also attributes the severe outbreak to low vaccination rates and the droughts, he says that the mosquito population rose sharply after the Mariana disaster. He believes the flood of waste material from the dam killed off frogs, the mosquito’s main predator.
At the Oswaldo Cruz Foundation, Márcia Chame says “there is no scientific data that links the disaster with yellow fever.”
On one point, however, she and Giuberti agree.
The outbreak turned a critical corner when the virus spread from the state of Minas Gerais, where it was regularly found, to the neighboring state of Espírito Santo, where it was not.
With no previous experience of yellow fever, many in Espírito Santo remained unvaccinated. The state began vaccinating rural residents on Jan. 23, a week after learning of its first human case, according to Giuberti.
For six days straight, health care teams worked furiously, vaccinating an average of 15,000 people a day.
Though rarer than it once was, yellow fever retains a hellish reputation among doctors.
“This disease has struck fear in the hearts of man ever since it was discovered. It’s so severe, so lethal, such a horrible death,” says Thomas P. Monath, who has been studying yellow fever since 1968, and now serves as chief scientific officer for BioProtection Systems Corp., an Iowa-based company involved in vaccine work.
Named for the sickly yellow color that permeates a patient’s skin and eyes, the virus likely emerged about 5,000 years ago, when it was transmitted from primates to humans in Central or East Africa.
In the 1600s, the disease and its most common carrier, Aedes aegypti, came to the Americas aboard slave ships. The U.S. experienced at least half a dozen epidemics, including one in Philadelphia in 1793 when the city was still the nation’s capital. Nearly 5,000 people died in three months, and more than one-third of Philadelphia’s 50,000 residents fled the city.
During construction of the Panama Canal in the early 1900s, yellow fever and malaria killed thousands of workers, prompting U.S. authorities to launch a campaign to improve sanitation and water, and to eliminate mosquito breeding sites.
Only in 1937 was a yellow fever vaccine developed by the South African biologist Max Theiler. Since then, vaccinations have helped rid many countries of yellow fever, though outbreaks continue to flare up in South America and Africa.
In Brazil, the outbreaks have not reached the cities in decades, remaining instead in the sylvatic, or jungle, cycle. Mosquitoes in the jungle pick up the virus from monkeys and pass it to other monkeys or humans working nearby.
In late December 2016, Angola declared the end of a year-long yellow fever epidemic that had spread to its African neighbor the Democratic Republic of Congo, causing 400 deaths in the two countries.
A week after Angola sounded the all-clear, Brazil’s human outbreak began in the state of Minas Gerais.
On Dec. 30, the first two yellow fever patients showed up at the bustling Santa Rosália Hospital in Teófilo Otoni, about 450 miles north of Rio de Janeiro.
The patients, both from the nearby town of Itambacuri, entered in critical condition, “vomiting blood,” says Rodrigo Lobo, a doctor of emergency medicine at Santa Rosália. “There was blood in their feces. The whites of their eyes went yellow and their urine looked darker.”
They were initially diagnosed with dengue fever, but the 39-year-old doctor wasn’t so sure. Lobo remembered hearing that monkeys had been found dead in Itambacuri several months prior; the cause was determined to be yellow fever. So he diagnosed the patients with yellow fever, and sent blood samples to be tested.
By the time the tests confirming his diagnosis came back more than two weeks later, both patients were long dead.
On New Year’s Day, sick people began arriving from other nearby towns and villages. Most were in the third and final stage of the disease. They had yellow eyes and skin, and were bleeding from their mouths.
“The walking dead,” Lobo called them.
The doctor worked around the clock, though there was little he could do. Every patient that first week died — 16 in all.
“In the beginning, I used to have nightmares,” Lobo says. “The evolution of the sickness is so quick. With all of the resources we were applying, to see young people dying was not easy. It was very hard to see people in the last stage bleeding, and you cannot do anything to stop the bleeding. It was horrifying.”
To make matters worse, doctors at Santa Rosália, which serves more than 60 municipalities, had not been paid for eight months due to a decrease in funding for public health. By the time of the outbreak, many employees had quit to pursue other jobs, forcing the hospital to cope with a scarcity of workers and even shortages of basic materials such as gauze and certain medicines.
Vaccination is mandatory for children born in 2002 or later, and many mothers get vaccinated when they bring in their children. Vaccination is far less common among men. The vast majority of yellow fever patients at Santa Rosália were men, usually age 50 or under. Many worked in the forest where they frequently came in contact with mosquitoes.
“There is a masculine attitude,” says Lobo, the doctor of emergency medicine. “ ‘I’m a Superman. I’m strong. I’m not going to get this.’ ”
“What happened here was a catastrophe,” Vitorio says. “A lot of young adults died because of a sickness that could have been avoided … A lot of children, they remain without family. The children were required to get the vaccine. The parents weren’t.”
Within a few weeks, the virus had spread to the state of Espírito Santo, where the population was even less prepared.
In São João Pequeno, 3-year-old Vitor Hugo Braun plays with LEGOs on the floor, while his grandparents describe what happened to his father, Virlei Braun.
“It was too quick,” Valdemar says, staring into the distance.
Virlei, who had never been vaccinated, fell ill almost three weeks after the first yellow fever patients had arrived at Santa Rosália. After lunch on a Sunday, he became feverish. The veins in his forehead bulged, his mother, Cecilia Braun, remembers.
The following day he went to the hospital in Colatina. Doctors thought he might have dengue or leptospirosis, a bacterial disease that can lead to kidney damage.
“Nobody knew what it was,” Valdemar says. “They left him for two days in bed. They were giving him medicines and putting tubes into him without knowing what it was.”
Virlei remained in the hospital on Jan. 27, his son’s third birthday.
“Mom,” he said, “bring my son. I want to give him a kiss on his birthday.”
Since the hospital would not allow children to visit, Virlei tried to rise from bed to go see Vitor Hugo at his school. But as Cecilia Braun helped her son struggle to his feet, Virlei shuddered in pain.
“Mom,” he said. “I cannot.”
He slumped back onto the bed. Two days later, doctors realized he was bleeding internally. They still had not diagnosed the disease.
Virlei heard his mother crying, and called on her to be strong.
He died a few days later on Feb. 1. Only after death was he diagnosed with yellow fever, his parents say.
They brought his body home for the funeral and tried to keep Vitor Hugo from seeing it. But the little boy peeked in the room where the body lay.
He kept asking his grandmother: “Is he sleeping? Is he sleeping? Is he sleeping?”
A week or two after Virlei’s death, the virus arrived in the state of Rio de Janeiro, in a village known as Córrego da Luz, “River of Light.”
Some of the locals believe the disease was brought by a tourist from the state of Minas Gerais. They had not heard of any sick monkeys.
However, researchers from the Oswaldo Cruz Foundation came to investigate the outbreak and found a dozen dead monkeys in the forests around the village, Márcia Chame says.
The first villager to be sickened was an energetic jokester named Watila Santos, who was 38 and married. Watila worked in construction, drove trucks and grew bananas and oranges. He and his wife had just moved to the village in January to live with relatives in a small cluster of houses built on a cleared patch of forest.
A group of men, including Watila, had gone into the jungle around the end of January to check on an area where oranges had been planted. Soon afterward Watila became sick with a fever and headache. When he went into the local hospital, “they said, ‘This is a simple virus. Go back home,’ ” his brother, Roberto dos Santos, says.
Watila spent four days sick at home. On the fifth day, his vomit was black.
“On Friday he was falling apart. When he went to the hospital and was taken to the infectologist area,” Roberto says, “it looked like his body had been painted yellow.”
It was now early in February. During a visit from his mother, Watila told her, “I’m not going to leave this hospital.”
About this time, a few others from Córrego da Luz fell ill.
Alessandro Valença Couto, a 38-year-old social services worker, who’d never had a serious illness before, felt at first like he had a cold. But on Feb. 5, after two days of illness, he began to vomit. Like others, he had not received the yellow fever vaccine and never wore insect repellent.
“Here, it has always been a lot of mosquitoes,” he says, explaining why many don’t bother with repellent.
Although Alessandro also went to the hospital, doctors said his illness might be meningitis or leptospirosis. He was then transferred to a bigger hospital, the State Infectology Institute in São Sebastião. Doctors diagnosed him with yellow fever and kept him hydrated through an IV line. He would spend 10 to 12 days in the hospital.
“It was horrible,” recalls Alessandro’s wife, Luciana Moreira. “I felt afraid of losing him.”
As she worried, another villager lost his fight. On Feb. 11, at 3 in the morning, Watila Santos died. Although he had always appeared healthy, relatives said he had other medical problems that may have left him unable to fight off the yellow fever virus. Within days of his death, some 30,000 people were vaccinated in the nearby city of Casimiro de Abreu.
Alessandro proved more fortunate than Watila. A little less than a week after his neighbor’s death, Alessandro went home to his wife and their 3-year-old son, Davi Luiz. He still suffers from pain in his stomach and worries that he may have permanent damage. But the family is glad he survived.
In mid-April, Luciana Moreira was pregnant. She and her husband plan to name their new son Bernardo.
Cecilia Braun says that her son, Virlei, had a favorite Bible passage, which was read at his funeral: John 16:32.
A time is coming and in fact has come when you will be scattered, each to your own home. You will leave me all alone. Yet I am not alone, for my father is with me.
She agonizes over her son’s death, thinking maybe they should have taken him to a better hospital the instant his illness appeared serious.
“That’s where we have failed,” Valdemar Braun says quietly.
The sun is beginning to set over their little village. It’s the time of day when Virlei used to return from his farm work to pick up Vitor Hugo. There is a brief silence.
“Now, I want to ask you a question,” says Cecilia Braun, looking as if she is straining to understand something beyond her grasp.
“Do you think that just a little mosquito can take the life of such a big, strong man?”