Scavengers are exposed to endless infections due to their diet based on decomposed organic matter. Various research has attempted to explain how these species avoid getting sick. No one has been able to discover it with certainty. Despite this, the scientific community assures that understanding in detail the immunological defense mechanisms of these living beings could improve medicine and human health.
Researchers around the world have put forward multiple theories that try to explain how some animals can eat carrion. A study led by Daniel Blumstein, an ecologist at the University of California, Los Angeles (UCLA), analyzed eight hypotheses in this regard that have been presented over the last few decades. The objective was to evaluate the validity and strength of its foundations.
Studying scavengers can save humans
The revised conjectures cover different explanations. A work published in 1975 suggests that vultures eat at high speed to prevent bacteria from forming spores. Another one released in 2009 indicates that these birds urinate on their legs before eating food to kill pathogens. One more points out that the baldness characteristic of some of these species is a physiological modification that facilitates cleaning and reduces exposure to viruses. For its part, research from 2015 qualifies the food washing behavior seen in raccoons as a protection technique.
Blumstein and his colleagues dismissed these approaches. “We did not find any solid basis that using urine to sterilize corpses, having a bald head, eating quickly or washing food reduce the risk of disease in scavengers,” they explain. On the contrary, they explain that the best supported claim involves the existence of enhanced immune systems in scavengers. These include physical barriers such as the skin and immune surveillance adaptations such as natural killer cells and phagocytic leukocytes (white blood cells).
Seven of the studies considered evaluated hypothetical immune processes in mammals, birds and reptiles. They agree that vultures have an enriched innate immunity, compared to their peers that prefer fresh food. Experts point out that maintaining a low gastric pH, avoiding foods with several days of decomposition and the presence of a specialized microbiome and optimized immune defenses are the theories that most accurately justify how scavengers survive their diet. However, the authors note that the current data are insufficient to determine a single strategy. “The limited number of studies tells us that we need more research to really understand how they do it,” adds Blumstein.
The UCLA specialist emphasizes that accelerating the exploration of the topic can lead to the discovery of new alternatives to combat infections in humans and counteract the resistance of pathogens to drugs.
Today, resistant bacteria kill more than a million people a year. A new study of the project Global Research on Antimicrobial Resistance (GRAM) reveals that without a change in disease prevention and the search for new antibiotics, deaths caused by these ‘superbacteria‘ could approach 2 million annually in 2050.
“Antibiotic resistance is an immense threat to global public health. Scavengers can disperse pathogens over long distances as they search for their next meal. From a biomimetic perspective, some of their defense mechanisms could potentially be used to improve human and veterinary medicine,” concludes Blumstein.
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