Washington, Oct 16 (IANS) The fact that humans eat often and a lot may explain why most people are protected from the majority of fungal pathogens, says a new study.
The study showed that the elevated body temperature of mammals, the familiar 98.6 degrees Fahrenheit, is too high for the vast majority of potential fungal invaders to survive.

“Fungal strains undergo a major loss of ability to grow as we move to mammalian temperatures,” said Arturo Casadevall, a professor at the Albert Einstein College of Medicine.

Casadevall conducted the study with Vincent A. Robert of Fungal Biodiversity Centre of Utrecht, the Netherlands.

“Our study makes the argument that our warm temperatures may have evolved to protect us against fungal diseases,” said Casadevall.

“And being warm-blooded and therefore largely resistant to fungal infections may help explain the dominance of mammals after the age of dinosaurs.”

There are roughly 1.5 million fungal species. Of these, only a few hundred are pathogenic to mammals. Fungal infections in people are often the result of impaired immune functioning.

Conversely, an estimated 270,000 fungal species are pathogenic to plants and 50,000 species infect insects. Frogs and other amphibians are prone to fungal pathogens. Fungi are also important in the decomposition of plants.

Researchers examined how 4,082 different fungal strains grew in temperatures ranging from chilly - four degrees Celsius or 39 degrees Fahrenheit - to desert hot, 45 degrees Celsius or 113 degrees Fahrenheit.

They found that nearly all of them grew well in temperatures up to 30 degrees celsius. Beyond that, though, the number of successful species declined by six percent for every one degree Celsius increase.

Most could not grow at mammalian temperatures. Those that did well in hotter conditions were often from warm-blooded sources.

Casadevall noted that the current study covered thousands of fungal strains and made use of a computerised database from Utrecht.

In the past, this type of research would have required retrieving this information manually, which would have been an extremely time-consuming task, Casadevall pointed out.

The results of the study, he added, could help explain why mammals maintain a seemingly energy-wasteful lifestyle requiring a great deal of food. Conversely, reptiles need to eat only once a day or even less often.

These findings were published in the Journal of Infectious Diseases.