Zoonoses are human diseases of animal origin. Bats world-wide harbour a greater proportion of viruses than several other groups of mammals. These viruses often don’t seem to harm the bats that carry them, which points to a long history of co-evolution. ‘Spillovers’ from bats to people either occur directly, through contact with infected bats or indirectly through intermediate hosts such as domestic animals or wildlife that have been contaminated by blood, saliva, urine or faeces of bats.
Zoonotic diseases are diseases that originate in animals and can be infected by humans. Bats around the world carry more viruses than other mammals. These viruses usually do not seem to harm bats that carry them, suggesting that viruses and bats have undergone a long history of co-evolution. Transmission from bats to humans occurs either directly through contact with infected bats or indirectly through intermediate hosts, including domestic or wild animals contaminated with blood, saliva, urine, or feces from bats.
Outbreaks of such zoonotic diseases have increased in recent decades often as a result of bushmeat consumption as well as human encroachment into natural habitats involving deforestation and agricultural intensification. This article reviews some of the bat borne zoonotic viruses that have made the headlines in recent years, including Ebola, Marburg, SARS-CoV, MERS-CoV, Hendra, Nipah, and Lyssavirus.
Outbreaks of zoonotic diseases have increased in recent decades, one due to predation on wildlife and the other due to human invasion of natural habitats through deforestation and increased agricultural land. This article describes some of the zoonotic viruses carried by bats that have attracted attention in recent years, including Ebola, Marburg, SARS, Middle East Respiratory Syndrome, Hendra, Nipah, and Lisa.
<h2 class="page-small-heading" > Ebola virus</h2>
In late August 2007 information began to trickle in to health authorities on an unidentified illness in a remote area of the Kasai-Occidental Providence in the Democratic Republic of Congo. The case reports listed a number of bad symptoms-fever, severe headache, vomiting, major abdominal pain, bloddy diarrhea, and severe dehydration. The first recognized cases were on June 8, following the funerals of two village chiefs. Tellingly, the entire first group of individuals infected had assisted with the burials. Researchers discovered that it was caused by the Ebola virus.
At the end of August 2007, the health authorities of the Democratic Republic of the Congo continued to receive reports of an unknown disease in a small, remote village in Providence, Kasai Western Province. Case reports list a range of severe symptoms, including fever, severe headache, vomiting, stomach aches, bloody diarrhea, and severe dehydration. The first cases were detected on 8 June, just after the funerals of two village leaders. It is worth noting that the first infected people have helped at funerals. The researchers found that these cases were caused by the Ebola virus.
Ebola, is the most serious of these recently emerged zoonotic viruses, in terms of human mortality. Sporadic outbreaks of this haemorrhagic disease have been known for 40 years in isolated forest villages across central Africa. The outbreaks spread in waves, accounting for up to a few hundred deaths before abruptly dying out, often before public health authorities could respond. In the recent outbreak in West Africa, the virus had mutated to become more infectious and improved transport links meant that it soon entered towns and cities. Nearly 30,000 people were infected of whom over 11,000 died.
Ebola has the highest fatality rate among zoonotic diseases that have emerged in recent years. The haemorrhagic disease has been erupting from time to time in isolated forest villages in central Africa for more than 40 years. The virus spread in waves, killing hundreds of people before it suddenly disappeared, and the public health departments did not have time to respond. In the most recent outbreak in West Africa, the virus mutated more contagiously, and coupled with a well-developed transportation network, the virus quickly spread to towns. Nearly 30,000 people were infected in the outbreak, including 11,000 deaths.
It is thought that fruit bats of the Pteropodidae family are natural Ebola virus hosts.
Fruit bats of the family Pterocarpus are the natural hosts of the Ebola virus.
<h2 class="page-small-heading" > Marburg Marburg virus</h2>
Marburg virus was first recognized in 1967, when outbreaks of hemorrhagic fever occurred simultaneously in laboratories in Marburg and Frankfurt, Germany and in Belgrade, Yugoslavia (now Serbia). Thirty-one people became ill, initially laboratory workers followed by several medical personnel and family members who had cared for them. Seven deaths were reported. The first people infected had been exposed to imported African green monkeys or their tissues while conducting research.
Marburg virus was first detected in 1967, when a disease called haemorrhagic fever broke out simultaneously in laboratories in Marburg and Frankfurt, Germany, and Belgrade, Yugoslavia (now Serbia). A total of 32 people fell ill, initially lab workers, followed by several paramedics and family members caring for them. There were 7 deaths. The first person infected had contact with imported African green monkeys or their tissues while doing the study.
The reservoir host of Marburg virus is the African fruit bat, Rousettus aegyptiacus. Fruit bats infected with Marburg virus do not to show obvious signs of illness. Primates (including humans) can become infected with Marburg virus, and may develop serious disease with high mortality.
The reservoirs of Marburg virus are African fruit bats, Egyptian fruit bats. Fruit bats infected with Marburg virus have no obvious signs of illness. Primates, including humans, can be infected with Marburg virus, which can lead to serious diseases with high lethality rates.
<h2 class="page-small-heading" > Severe Acute Respiratory Syndrome severe acute respiratory syndrome</h2>
Severe Acute Respiratory Syndrome (caused by the coronavirus SARS-CoV) first occurred in 2002 in China and spread throughout the world (thus becoming a pandemic) with over 8000 confirmed cases of which nearly 800 were fatal. Soon after the outbreak, the virus was found in masked palm civets and raccoon dogs in a market in Guangdong Province and it took some time before horseshoe bats were identified as the natural hosts, from which the virus had spilled over to the carnivores.
Severe acute respiratory syndrome (caused by the SARS-CoV coronavirus) first appeared in China in 2002 and then spread around the world (thus becoming a global epidemic), eventually with more than 8,000 confirmed cases, including nearly 800 deaths. After this outbreak, the virus was found in civets and tanuki in a market in Guangdong Province, and it took some time to determine that the horseshoe bat was the natural host, and the virus was transmitted from the horseshoe bat to the carnivores.
<h2 class="page-small-heading" > Middle East Respiratory Syndrome Middle East Respiratory Syndrome</h2>
Middle East Respiratory Syndrome (also caused by a coronavirus, MERS-CoV) was first reported on the Arabian peninsula in 2012, is spread mainly by human to human contact and has infected around 1200 people worldwide, about 450 of whom have died. Because a small fragment of viral DNA from an Egyptian tomb bat (Taphozous perforatus) was found to be identical with that from the first MERS patient, it was suspected that bats were the natural reservoirs, but that has not been substantiated, and no other bat has been found to carry MERS. Instead most human infections have been traced to close contact with dromedary camels.
Middle East respiratory syndrome (also caused by a coronavirus called MERS-CoV) was first reported in the Arabian Peninsula in 2012 and spreads mainly through human-to-human contact, with about 1,200 people infected worldwide, of whom about 450 died. Because a small fragment of viral DNA from an Egyptian tomb bat was found to be identical to that of the first MERS patient, bats were suspected to be the natural reservoir of MERS virus, but it was not confirmed or found that other bats carried MERS virus. Conversely, most infected people have had close contact with dromedaries.
<h2 class="page-small-heading" > Hendra virus</h2>
Hendra was first detected in Australia during an outbreak of infectious respiratory disease in horses and humans in 1994. There have been several subsequent spillovers resulting in seven human cases and four deaths. Pteropodid bats have been confirmed as reservoirs of the disease. Horses became infected when they grazed on pastures infected with bat urine and passed on the disease to those caring for them. However with appropriate horse husbandry, the disease has been contained.
Hendra virus was first detected in Australia in 1994, when infectious respiratory diseases broke out in horses and humans. There were several subsequent transmissions, resulting in 7 infections and 4 deaths. Pterodactyl bats have been shown to be reservoirs of Hendra virus. When horses graze on pastures infected with bat urine, they become infected and pass the disease on to those who care for them. However, with proper horse rearing management, the disease was brought under control.
<h2 class="page-small-heading" > Nipah nipah virus</h2>
Nipah, was first isolated in 1998 in pigs and pig workers suffering from encephalitis in Malaysia, where 265 cases resulted in 105 deaths. Cessation of pig movements and culling over a million pigs brought the disease under control. The experience with Hendra soon led to fruit bats being identified as the source of infection, with pigs eating fallen fruit contaminated by bats.
Nipah virus was first isolated from pigs and pig breeders suffering from encephalitis in Malaysia in 1998, and this time a total of 265 people were infected, 105 of whom died. Stopping the flow of hogs and culling more than 1 million pigs brought the disease under control. Because of their experience in dealing with Hendra virus, fruit bats were quickly identified as the source of infection, and pigs ate fruit that fell to the ground after being contaminated with bats.
Since 2001 however human cases have occurred almost annually in Bangladesh and occasionally nearby in India, with higher fatality rates than in Malaysia and with a different route of infection. This occurs mainly by drinking palm sap infected with the virus by the Indian flying fox (Pteropus giganteus). Preventing access by bats to the pots which collect the sap has reduced the infection rate.
However, bangladesh has experienced almost every year of human infections since 2001, and neighbouring India has occasionally seen human infections, with a higher fatality rate than Malaysia and different routes of infection. People are infected by drinking palm juice infected by a virus carried by the Indian giant fox bat. Preventing bats from approaching jars where palm juice is collected reduces infection rates.
<h2 class="page-small-heading" > Lyssavirus Lisa virus</h2>
In early July 2002 in Franklin County, Tennessee, a thirteen-year-old boy named Jeremy Watkins picked up a sickly bat on his way home from a day of fishing. None of the other family members handled it, and his stepfather wisely made him release the animal soon after Jeremy revealed his find.
In early July 2002, in Franklin County, Tennessee, U.S., 13-year-old boy Jeremy Watkins returned home from fishing when he picked up a sick bat on the way. After Jeremy told everyone about the bat, the family did not touch it, and the stepfather wisely asked him to let the bat go.
On August 21 Jeremy complained of headache and neck pain. Then a day or so later his right arm became numb and he developed diplopia, or double vision, and a constant, queasy confusion. Three days later he was taken to the local hospital's emergency room but was discharged with the incorrect diagnosis of "muscle strain". The next day he was back in the emergency room, this time with a fever of 102℉. He had the same symptoms, but now his speech was slurred, he had a stiff neck, and difficulty swallowing.
On August 21, Jeremy said she had a headache and a sore neck. After a day or two, his right arm became numb, and there began to be ghosting in front of his eyes, followed by vomiting and confusion. Three days later he was taken to the emergency room of a local hospital but was discharged after being misdiagnosed as a "muscle strain.". The next day he went back to the emergency room, this time with a fever of 102 degrees Fahrenheit. His symptoms were the same as before, but this time he couldn't speak clearly, his neck stiffened and he had difficulty swallowing.
At this point, Jeremy was transferred to a local children's hospital. By August 26 he could no longer breathe or think normally. He was also producing copious amounts of saliva. Highly agitaged to the point of being combative, Jeremy was sedated and put on life support. His mental status deteriorated rapidly and by the next morning he was completely unpresponsive. On August 31 Jeremy was pronounced brain-dead and following the withdrawal of life support, he died of bat-borne lyssavirus.
At this point, Jeremy was transferred to the local children's hospital. By August 26th, he was unable to breathe and think normally. He also spat out a lot of white foam and was so excited that the doctor had to give him a sedative and a life support system. His mental state deteriorated rapidly, and by the next morning he had completely lost his reaction to the outside world. On August 31, Jeremy was declared brain dead and the life support system was withdrawn. He died of the Lisa virus carried by bats.
Lyssavirus causes rabies and the genus is rapidly growing, with 15 species currently recognised (including EBLV), all but two of which have been isolated from bats. The best known is classical rabies virus (RABV) which remains one of the most significant human zoonoses, killing tens of thousands of people each year in Africa and Asia following dog bites, according to the World Health Organisation. Vampire bat rabies, caused by the same virus species, is a major public health threat in Latin America.
Lisa virus causes rabies, and the number of newfound genotypes in the genus is increasing rapidly, with 15 known viruses (including EBLV) of different genotypes, all but two of which have been isolated from bats. The most famous is the classic rabies virus (RABV), which remains one of the most important zoonotic diseases in humans, according to the World Health Organization, killing tens of thousands of people who have been bitten by dogs in Africa and Asia each year. Vampire bat rabies is also caused by the same virus, RABV, and is a major threat to public health in Latin America.
<h2 class="page-small-heading" > words and phrases</h2>
1. Domestic animals, domestic animals.
2. saliva, [səˈlaɪvə], n. saliva.
3. dehydration,[ˌdiːhaɪˈdreɪʃn],n. dehydration.
4. in terms of something, from... Aspect, as far as... Foregoing.
It's a mistake tothink ofFlorida onlyin terms ofits tourist attractions. It's a mistake to think only about Florida from the point of view of tourist attractions.
5. spread, [spred], v. propagation.
6. Care for somebody/something, take care of someone/something.
He thanked the nurses who had cared for him. He thanked the nurses who had taken care of him.
7. Expose somebody to something and put someone in a dangerous situation.
The report revealed that workers had been exposed to high levels of radiation. Reports show that workers are exposed to excessive levels of radiation.
8. rabies, [ˈreɪbiːz], n. rabies, hydrophobia.
<h2 class="page-small-heading" > English source</h2>
https://www.bats.org.uk/about-bats/bats-and-disease/bats-and-viruses
https://www.cdc.gov/vhf/marburg/index.html
https://www.who.int/health-topics/ebola/#tab=tab_1
The Viral Storm: The Dawn of a New Pandemic Age by Nathan Wolfe