Washington: Researchers have found that populations living in higher altitudes, especially 3,000 meters (9,842 feet) above the sea level significantly report lower levels of coronavirus infections than their lowland counterparts.
The Washington Post cited one peer-reviewed study, published in the journal Respiratory Physiology & Neurobiology, in which researchers from Australia, Bolivia, Canada and Switzerland looking at epidemiological data from Bolivia, Ecuador and Tibet found that Tibet’s infection rate was “drastically” lower than that of lowland China, three times lower in the Bolivian Andes than in the rest of the country and four times lower in the Ecuadoran Andes.
Cusco in Peru, a picturesque Andean valley, the high-altitude city of 420,000 residents, had only recorded the death of three tourists from Mexico, China and Britain, between March 23 and April 3, at the start of Peru’s strict national lockdown. Since then, 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 916 of Peru’s 141,000 cases come from the Cusco region, meaning its contagion rate is more than 80 per cent below the national average.
The contagion’s connection to high-elevation regions has prompted speculation from researchers that the coronavirus gets ‘soroche’, the Quechua word for altitude sickness.
Similarly, Ecuador has suffered one of Latin America’s worst outbreaks, with more than 38,000 reported cases and more than 3,300 deaths, according to official figures. But it has been centred on the Pacific port of Guayaquil. Bolivia’s 8,387 cases have been concentrated in the department of Santa Cruz, just a few hundred feet above sea level. But the department of La Paz, home to the world’s highest capital, has had just 410 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, the media reported further.
Just three populations in the world have been found to have genetic adaptations to altitude: Himalayans, Ethiopian highlanders and Andeans. Yet Clayton Cowl, a pulmonologist at the Mayo Clinic and a former president of the American College of Chest Physicians, suspects the trend may be more closely related to acclimatization, the body’s ability to adjust temporarily to altitude, than to DNA.
Cowl notes that prolonged exposure to altitude triggers a chain reaction in the lungs involving a protein known as ACE2 that might prevent pulmonary shunting, a problem common among COVID-19 patients.
Ordinarily, when a part of the lung is damaged, the body redirects the flow of blood toward healthier areas that are better able to absorb oxygen. Shunting stops that process of redirection, resulting in hypoxia. It is, according to Cowl, a common element among the roughly 30 per cent of COVID-19 patients who exhibit mild symptoms yet have unusually low levels of oxygen in their blood — and who sometimes take a sudden turn for the worse.
But researchers are still looking for more evidence to establish the 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, a researcher on infectious diseases from the University of California in 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,” he added.