Infectious Diseases at High Altitude

Abstract

Travel to elevations above 2,500 m is an increasingly common activity undertaken by a diverse population of individuals. These may be trekkers, climbers, miners in high-altitude sites in South America, and more recently, soldiers deployed for high-altitude duty in remote areas of the world. What is also being increasingly recognized is the plight of the millions of pilgrims, many with comorbidities, who annually ascend to high-altitude sacred areas. There are also 400 million people who reside permanently in high mountain ranges, which cover one-fifth of the Earth's surface. Many of these high-altitude areas are in developing countries, for example, the Himalayan range in South Asia. Although high-altitude areas may not harbor any specific infectious disease agents, it is important to know about the pathogens encountered in the mountains to be better able to help both the ill sojourner and the native high-altitude dweller. Often the same pathogens prevalent in the surrounding lowlands are found at high altitude, but various factors such as immunomodulation, hypoxia, poor physiological adaptation, and harsh environmental stressors at high altitude may enhance susceptibility to these pathogens. Against this background, various gastrointestinal, respiratory, dermatological, neurological, and other infections encountered at high altitude are discussed.

A Higher Altitude Is Associated with Increased Incidence of Infections following Primary Total Hip Arthroplasty

“…High altitude surgical procedures constitute a unique challenge due to the hypoxic environment in which they are performed, which may lead to several postoperative consequences. Within this oxygen-depleted environment, a patient's oxygen-saturation curve is altered, and saturation percentages are decreased rendering patients more susceptible to systemic infection 6 7 8) . A literature review found little detail regarding the effect of high altitudes on postoperative infections in primary THA.…”

“…With a decrease in the partial pressure of oxygen at higher altitudes, systemic variations in the oxygen-hemoglobin curve and oxygen saturation percentages can lead to a state of constant endothelial cell damage and repair 2 3 4 5) . Higher altitudes also alter immune responses, therefore potentially creating an immunosuppressive environment for patients 6) . The hypoxic environment, paired with the various systemic physiological changes associated with higher altitudes, can lead to an increased susceptibility to infectious pathogens postoperatively 6 7 8) .…”

“…Higher altitudes also alter immune responses, therefore potentially creating an immunosuppressive environment for patients 6) . The hypoxic environment, paired with the various systemic physiological changes associated with higher altitudes, can lead to an increased susceptibility to infectious pathogens postoperatively 6 7 8) . Further exploration of the relationship between higher altitude and postoperative infections in primary total hip arthroplasties (THA) is important given that the hypoxic conditions and systemic stress on the body could potentiate such complications.…”

Differential expression of skeletal muscle mitochondrial proteins in yak, dzo, and cattle: a proteomics-based study

“…Research into the molecular mechanisms that enable high-altitude adaptation in mammals of the plateau is important for preventing and treating hypoxia and related diseases [ 2 , 3 , 12 , 17 , 19 , 25 ]. The yak, an essential animal in Tibet, provides food, shelter, fuel, and transport for the local people, largely due to its ability to adapt to cold, low-oxygen, and low-atmospheric pressure environments.…”

AMPK and the Need to Breathe and Feed: What’s the Matter with Oxygen?

“…When considering metabolic and respiratory disease in the context of oxygen supply at altitude, it is of further intrigue to note that while there is evidence of increased susceptibility to some infections at high altitude [210], those living at and adapted to high altitude (Andeans and Tibetans) may be less likely to develop severe adverse respiratory dysfunction during other infections, such as SARS-CoV-2 (COVID-19) [211]. Given that the innate and adaptive immune responses are subject to modulation by hypoxia [212], it is significant that they can be modulated by AMPK, in addition to HIFs-α, in either a beneficial or detrimental way depending on the nature of infection [213].…”