Birds do it. Bees do it. Many species practice social distancing to cut down on the spread of disease. From ant colonies that restrict movements within the nest to lobsters that refuse to share dens, animal quarantine is an important aspect of the animal kingdom.
How Do Diseases Spread Through Animals?
Animal quarantine usually involves changing behaviors to interrupt the disease’s route of transmission. So, how do diseases spread through animals? Pathogens typically travel through urine or feces, and many animals use their enhanced sensory abilities to pick out diseased group members.
Some even go as far as to attack and drive them off. Sydney Combs of National Geographic even describes how chimpanzees actively drive off sick individuals. In 1966, Jane Goodall observed the shunning of a polio-stricken chimpanzee while studying them in Gombe Stream National Park. As Combs writes, “In one instance, the partially paralyzed chimp approached chimps grooming in a tree; starved of social contact, he reached out a hand in greeting, but the others moved away without a backward glance.”
Smithsonian Magazine notes that mandrills use olfactory clues from feces to cut down on grooming parasitized troop members, thereby minimizing infection. And National Geographic also explains how spiny lobsters can sniff out infection markers in urine and thus avoid den mates infected with the highly contagious Panulirus argus mininuceovirus.
However, shunning infected individuals is a risky animal quarantine strategy, as it leaves the shunned vulnerable to environmental stress, such as cold, and without protection from predators.
Organizational isolation is an animal quarantine strategy used in highly social societies to cut down on disease transmission. Where population density is unavoidable, animals such as ants reduce interactions between groups within the nest. This minimizes contact with highly vulnerable members, such as the queen and her larvae.
Undark describes how researchers used mini QR codes glued to ants in an experimental colony to track movements within the nest during a disease outbreak. Once the ants sensed disease, social interactions soon reduced. Ants began limiting themselves to defined groups, and these groups then got smaller. Each ant in the nest experienced limits on movement, with those more at risk of harboring the infection locked down the most.
Cutting Down Contamination
By bringing out their dead, ant colonies attempt to minimize disease spread and contamination within the nest. Ants regularly remove dead or diseased insects during outbreaks, according to BBC Future. Similarly, bees will sniff out and discard larvae infected by foulbrood as soon as possible to keep the hive clean.
Some social animals voluntarily sacrifice themselves to reduce disease risk. It’s an extreme animal quarantine tactic seen in mice and ants that leaves the infected individual outside the nest and less of a risk.
The Washington Post reports a study showing that, when mice quarantined themselves outside the nest, infection transmission rates dropped by 40 percent.
And some even sacrifice vulnerable members within their social groups. Termites cannibalize their young to remove a potential pool of vulnerable individuals that could serve as a reservoir of disease.
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