Bats and the Origins of Outbreaks
2021-03-08
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1Scientists have long suspected that the rate of new infectious diseases could speed up.
2This is especially possible in developing countries where human and animal contact is increasing.
3Changes in the environment are moving many species of animals into new living spaces.
4Those movements, combined with more human contact with animals as people move deeper into forests, increases the chances of a virus jumping species.
5This is what appears to have happened in China with the coronavirus that causes COVID-19.
6Like many infectious viruses introduced this way, the outbreak seems to have started with bats.
7Diseases that can jump from animals to humans are called zoonotic diseases.
8These diseases can be problematic because the human body is not designed to defend against this kind of invasion.
9The host animal species often shows no signs of disease.
10This is because the animal's body has already learned to deal with the virus.
11However, when such viruses or other disease-causing microorganisms jump from animals to humans, the effects can be deadly.
12Many scientists believe bats were the first carriers of the coronavirus that causes COVID-19.
13The animals have been linked to past outbreaks of coronaviruses in humans.
14Studies have shown that bats are natural hosts to many other viruses as well.
15One example is the Ebola virus, which caused deadly outbreaks in Western Africa.
16The Nipah virus, also carried by bats, has caused human outbreaks across South and Southeast Asia.
17Health experts say Nipah is serious enough to possibly cause a "serious epidemic."
18The coronavirus family of viruses also includes diseases such as Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS).
19Scientists have discovered that SARS and MERS were caused by viruses that started in bats, with other animals serving as intermediate hosts.
20The only other animals coming close to hosting as many viruses as bats are rodents.
21There are about 2,300 species of rodents, making up about 40 percent of all mammals.
22While rodents are believed to have more viruses as a group, bats host more viruses per species.
23Scientists believe the many types of species in both groups can create more possibilities for viruses.
24Some bats live in forests while others are found in caves.
25Most eat insects such as beetles, moths and mosquitoes.
26Some bats eat fruit, nectar, seeds and pollen from flowers.
27Others eat small animals such as birds, fish, frogs and lizards.
28A small number of bats feed on blood.
29Bats also provide many benefits to the environment.
30Some bats play important parts in plant pollination and spreading seeds.
31Bats can pollinate more than 500 species of plants including avocados, bananas, dates and mangoes.
32In Southeast Asia, durian, a highly valued fruit, can be effectively pollinated only by the Dawn Bat.
33In this way, bats are important economically for people.
34Insect-eating bats also serve to naturally control insect populations.
35These bats eat millions of insects at night, including some that cause severe damage to crops.
36I'm Jonathan Evans.
1Scientists have long suspected that the rate of new infectious diseases could speed up. This is especially possible in developing countries where human and animal contact is increasing. 2Changes in the environment are moving many species of animals into new living spaces. 3Those movements, combined with more human contact with animals as people move deeper into forests, increases the chances of a virus jumping species. 4This is what appears to have happened in China with the coronavirus that causes COVID-19. Like many infectious viruses introduced this way, the outbreak seems to have started with bats. 5Diseases that can jump from animals to humans are called zoonotic diseases. These diseases can be problematic because the human body is not designed to defend against this kind of invasion. 6The host animal species often shows no signs of disease. This is because the animal's body has already learned to deal with the virus. However, when such viruses or other disease-causing microorganisms jump from animals to humans, the effects can be deadly. 7Many scientists believe bats were the first carriers of the coronavirus that causes COVID-19. The animals have been linked to past outbreaks of coronaviruses in humans. Studies have shown that bats are natural hosts to many other viruses as well. 8One example is the Ebola virus, which caused deadly outbreaks in Western Africa. The Nipah virus, also carried by bats, has caused human outbreaks across South and Southeast Asia. Health experts say Nipah is serious enough to possibly cause a "serious epidemic." 9The coronavirus family of viruses also includes diseases such as Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS). Scientists have discovered that SARS and MERS were caused by viruses that started in bats, with other animals serving as intermediate hosts. 10The only other animals coming close to hosting as many viruses as bats are rodents. There are about 2,300 species of rodents, making up about 40 percent of all mammals. While rodents are believed to have more viruses as a group, bats host more viruses per species. 11Scientists believe the many types of species in both groups can create more possibilities for viruses. 12Some bats live in forests while others are found in caves. Most eat insects such as beetles, moths and mosquitoes. Some bats eat fruit, nectar, seeds and pollen from flowers. Others eat small animals such as birds, fish, frogs and lizards. A small number of bats feed on blood. 13Bats also provide many benefits to the environment. Some bats play important parts in plant pollination and spreading seeds. Bats can pollinate more than 500 species of plants including avocados, bananas, dates and mangoes. 14In Southeast Asia, durian, a highly valued fruit, can be effectively pollinated only by the Dawn Bat. In this way, bats are important economically for people. 15Insect-eating bats also serve to naturally control insect populations. These bats eat millions of insects at night, including some that cause severe damage to crops. 16I'm Jonathan Evans. 17Julia Janicki and Simon Scarr reported on this story for the Reuters news service. Jonathan Evans adapted this story for Learning English. Bryan Lynn was the editor. 18________________________________________________________________ 19Words in This Story 20epidemic - n. an occurrence in which a disease spreads very quickly and affects a large number of people 21host - n. a living organism on or in which a parasite lives 22intermediate host - adj. a host which is normally used by a parasite in the course of its life cycle and in which it may multiply asexually but not sexually 23mammals - n. a type of animal that feeds milk to its young and that usually has hair or fur covering most of its skin 24pollen - n. the very fine usually yellow dust that is produced by a plant and that is carried to other plants of the same kind usually by wind or insects so that the plants can produce seeds 25outbreak - n. a sudden start or increase of fighting or disease 26species - n. group of animals or plants that are similar and can produce young animals or plants; a group of related animals or plants that is smaller than a genus