[bold](Article courtesy of Washington Post)[/bold]
When tourists from Mexico, China and Britain became the first covid-19 fatalities in Cusco, Peru, it seemed as if the onetime capital of the Inca Empire might be headed for a significant outbreak.
Nestled in a picturesque Andean valley, the high-altitude city of 420,000 residents, the gateway to the cloud forest citadel of Machu Picchu, receives more than 3 million international visitors per year — many from pandemic hot spots, including the United States, Italy and Spain.
Yet since those three deaths, between March 23 and April 3, at the start of Peru’s strict national lockdown, there has not been another covid-19 fatality in the entire Cusco region, even as the disease has claimed more than 4,000 lives nationally.
Infections have also remained low. Just 1,062 of Peru’s 164,000 cases come from the Cusco region, meaning its contagion rate is more than 80 percent below the national average.
The relative dearth of cases and deaths in the internationally connected but high-elevation region has prompted speculation here that the novel coronavirus gets soroche, the Quechua word for altitude sickness.
Similar results have been seen elsewhere in the Andes, and in Tibet.
Scientists warn that the apparent pattern might not last, but the as-yet-unexplained phenomenon has them intrigued. Researchers are starting to investigate a possible relationship between the coronavirus and altitude.
In one peer-reviewed study, published in the journal Respiratory Physiology & Neurobiology, researchers from Australia, Bolivia, Canada and Switzerland looking at epidemiological data from Bolivia, Ecuador and Tibet found that populations living above 3,000 meters (9,842 feet) reported significantly lower levels of confirmed infections than their lowland counterparts.
They found that Tibet’s infection rate was “drastically” lower than that of lowland China, the rate in the Bolivian Andes was one-third that of the rest of Bolivia, and the rate in the Ecuadoran Andes was one-fourth that of the rest of Ecuador.
Ecuador has suffered one of Latin America’s worst outbreaks, with more than 39,000 reported cases and more than 3,300 deaths, according to official figures. But it has been centered on the Pacific port of Guayaquil. Bolivia’s 9,982 cases have been concentrated in the department of Santa Cruz, a few hundred feet above sea level. But the department of La Paz, home to the world’s highest capital, has had 507 cases.
The researchers hypothesize that populations living at high altitudes might be benefiting from a combination of an ability to cope with hypoxia (low levels of oxygen in the blood) and a natural environment hostile to the virus — including dry mountain air, high levels of UV radiation and the possibility that lower barometric pressure reduces the virus’s ability to linger in the air.
Other experts question the role of the environmental factors, noting that most coronavirus infections occur indoors, making UV levels irrelevant. But they are calling for more research into high-altitude populations’ response to the coronavirus, including the possibility that when infected, they sicken less and are therefore less likely to seek medical treatment or testing.
“The virus likes people. It doesn’t care about altitude,” says Peter Chin-Hong, who studies infectious diseases at the University of California at San Francisco. “But we’re still learning so much about this disease, and this does provide us with some good clues to try and understand its progression.”
