How Bats Are Increasing Chances Of People Getting Infected With Novel Viruses

It’s no coincidence that some of the worst viral disease outbreaks in recent years — SARS, MERS, Ebola, Marburg originated in bats. And Bats are the most likely reservoir of the new coronavirus, SARS-CoV-2 as well.

A study published in the Science Daily finds that bats’ fierce immune response to viruses could drive viruses to replicate faster, so that when they jump to mammals with average immune systems, such as humans, the viruses wreak deadly havoc.

Some bats — including those known to be the original source of human infections — have been shown to host immune systems that are perpetually primed to mount defenses against viruses. Viral infection in these bats leads to a swift response that walls the virus out of cells. While this may protect the bats from getting infected with high viral loads, it encourages these viruses to reproduce more quickly within a host before a defense can be mounted.

This makes bats a unique reservoir of rapidly reproducing and highly transmissible viruses. While the bats can tolerate viruses like these, when these bat viruses then move into animals that lack a fast-response immune system, the viruses quickly overwhelm their new hosts, leading to high fatality rates.

Vigorous flight leads to longer lifespan — and perhaps viral tolerance

As the only flying mammal, bats elevate their metabolic rates in flight to a level that doubles that achieved by similarly sized rodents when running.

Generally, vigorous physical activity and high metabolic rates lead to higher tissue damage due to an accumulation of reactive molecules, primarily free radicals. But to enable flight, bats seem to have developed physiological mechanisms to efficiently mop up these destructive molecules.

Ecological Importance of Bats

There are over 1,000 species of bats, which make up over one-fifth of all mammal species on Earth. Bats are critical for the survival of several ecosystems — in dispersing seeds, pollinating rare flowers or eating large quantities of insects.

Bats have long been postulated to play important ecological roles in prey and predator, arthropod suppression, seed dispersal, pollination, material and nutrient distribution, and recycle.

Remains of 12 orders or classes of prey belonging to 18 taxonomic families of insects were reported in the diet of bats . The prey items include Acari, Arachnida, Coleoptera, Diptera, Hemiptera, Homoptera, Hymenoptera, Isoptera, Lepidoptera, Neuroptera, Orthoptera, and Trichoptera.

They also predate on frogs, fish, small mammals, and even blood of mammals and birds. Some species also eat unusual prey items such as scorpions and spiders. Bats exhibit high species diversity with multiple species forage sympatrically to avoid competition.

A resource partition is possible through the use of diverse mechanism like difference in wing shape, body size, and sensory cues.

In addition to insect suppression through predation, some bat species primarily the two families of bats (Pteropodidae in the Old World and Phyllostomidae in the New World) play important roles in plant pollination. Although bat pollination is relatively uncommon when compared with bird or insect pollination, it involves an impressive number of economically and ecologically important plants.

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Loss Of Habitat

Popular literature and entertainment instill fears in our minds about bats. They are associated with darkness and death.

Since they are a huge reservoir of viruses, the species is also plagued by its own group of diseases. The white-nose syndrome is one of the diseases that kills bats in large numbers.

Habitat loss has also led to large-scale economic impact and structural damages to forest ecosystems. It has forced bats to inhabit cities and other places with dense human population, increasing the risks of transmitting novel viruses.

Along with rats, bats are also considered as having the ability to transmit more deadly viruses to humans in the future.

The most common source of human rabies has been bats. These are also thought to be the hosts for ebola virus. Bats were also the reservoir host for nipah, marburg and the hendra virus. Read More here.