Could a better understanding of birds’ natural defense against fungus assist in humanity’s own fight against infections?
A new study says yes, finding that a specialized white blood cell in birds can destroy a potentially deadly fungal infection that strikes in over a million people each year.
A team of researchers at the University of Sheffield showed that the macrophage, a specific white blood cell in birds’ blood, blocks the growth of Cryptococcus neoformans, a fungus that leads to fatal infections in immunocompromised individuals.
Cryptococci, thought to result in hundreds of thousands of human deaths each year and especially endanger AIDS patients, are carried by birds, whose droppings are believed to be a human infection source. It has been unknown, however, why the creatures themselves do not fall ill from the fungi.
Dr. Simon Johnston and his colleagues discovered that the fungus undergoes slow growth in the bird’s digestive tract, and can still be spread even by healthy ones. However, the catch is it gets destroyed by the birds’ immune system once it attempts to invade their bodies.
“By studying bird cells under the microscope, we have seen that macrophage cells have the ability to completely block the growth of the fungus, which can be fatal in humans,” explains Dr. Johnston.
He added that that birds’ higher body temperature of 42 degrees Celsius (compared to humans’ 37 degrees C) alone is insufficient in stopping fungus dead in its tracks, making the role of macrophages highly critical in their protection.
The researchers are working on a global collaboration to study cryptococcosis further and how the human immune system can better defend against this fungus and related sicknesses.
The findings were published in the journal Nature Scientific Reports.
Birds are deemed key in spreading many human diseases – there are steep agricultural costs, for instance, when 170,000 poultry were culled because of a suspected outbreak of bird flu.
Viruses in bird flu, also referred to as avian flu, are carried by wild aquatic birds and then transferred to domesticated animals such as poultry chickens. Humans may get the viruses through direct contact with infected birds or a contaminated environment, or through an intermediate host such as a pig.
However, a look at birds’ resistance of deadly infections may lead to better intervention in a diverse range of human health issues, argues Dr. Johnston.