Coronavirus: the animal to human connection

Coronavirus is a virus passed from animals to humans.

This transfer of disease between species is called zoonoses. There are more than three dozen we can catch directly through touch and more than four dozen that result from bites.

Bacteria and viruses that are deadly to one type of creature can evolve quickly to infect another. While the coronavirus outbreak in China is the latest example , a host of infectious and deadly diseases have hopped from animals to humans and from humans to animals.

The cross-species infection can originate on farms or markets, which harbour ideal conditions for the swapping of genes. The latest coronavirus outbreak is believed to have originated at an illegal wildlife market in Wuhan.

The transfer can also occur from such seemingly benign activities as letting a performance monkey on some Indonesian street corner climb on your head. Microbes of two varieties can even gather in your gut, do some viral dancing, and evolve to morph you into a deadly, contagious host.

But disease-carrying parasites are not picky about hosts. Human diseases can decimate animal populations, too, from such well-meaning activities as ecotourism.

Coronavirus 

On 31 December 2019, the World Health Organisation was alerted to several cases of pneumonia in Wuhan City, in China. The virus did not match any other known virus. One week later, on 7 January, Chinese authorities confirmed that they had identified a new virus, a coronavirus, which is a family of viruses that include the common cold, and viruses such as SARS and MERS.

Coronaviruses are transmitted by animals and people, and this Wuhan strain has been linked to a market selling seafood and live animals. Chinese officials said human-to-human transmission of the virus has been confirmed. As of January 27, almost 3000 cases of the disease were reported in China, with 80 people confirmed dead. The number of cases found in the US and Europe was climbing.

To avoid contracting the virus:

  • Travellers are particularly at risk of this newest outbreak and should avoid direct unprotected contact with live animals and surfaces in contact with animals in markets
  • The consumption of raw or undercooked animal products should be avoided. Raw meat, milk or animal organs should be handled with care, to avoid cross-contamination with uncooked foods, as per good food safety practices.
  • Frequently clean hands by using alcohol-based hand rub or soap and water
  • When coughing and sneezing cover mouth and nose with flexed elbow or tissue – throw tissue away immediately and wash hands
  • Avoid close contact with anyone who has fever and cough
  • If you have fever, cough and difficulty breathing seek medical care early and share previous travel history with your health care provider

Influenza pandemics

Flu history is frightening: The 1918 influenza pandemic swept the world within months, killing an estimated 50 million people — more than any other illness in recorded history for the short time frame involved.

Unlike some flu strains that mainly kill the elderly, children, and those with compromised immune systems, the 1918 strain hit young adults hard. In one year, the average life expectancy in the United States dropped by 12 years.

Today, governments are more prepared, scientifically and logistically, to handle flu outbreaks.

Bubonic plague

Nothing beats the 14-century Black Death (also called Bubonic Plague) for sheer global impact of a single disease outbreak. Some 75 million died — at a time when there were only about 360 million to start with. Death came in a matter of days, and it was excruciatingly painful.

Plague is a bacterial disease and is carried by rodents and even cats, but becomes most deadly to us when transmitted between people. Symptoms include fever, chills, weakness, and swollen and painful lymph nodes. Even today, if not treated, death ensues.

Diseases that bite

The problem is growing, with insect-borne disease outbreaks becoming more common and more virulent. Scientists say the warming climate will only make matters worse.

Malaria infects 350 million or more people every year, and more than 1 million die, most of them young children in Africa south of the Sahara. Mosquito-borne dengue fever infects some 50 million people annually; about 500 000 are hospitalised and about 2.5 percent of those die.

Rabies kills about 55 000 people globally each year, mostly in Asia and Africa. Most deaths follow a bite from an infected pet dog, though wild animals can carry rabies too.

Hantavirus is carried mostly by deer mice. You can catch it by breathing dust contaminated with mouse droppings.  It is incurable, but most people recover. About 1 percent die.

Humanimmunodeficiency virus (HIV), the virus that causes AIDS, originated from chimps and other primates and is thought to have first infected humans at least a century ago. It destroys the immune system, opening the door to a host of deadly infections or cancers. Two-thirds of HIV infections are in sub-Saharan Africa.

• Ebola is a widespread threat to gorillas and chimps in Central Africa, and may have spread to humans from people who ate infected animals. It is now transmittable human-to-human, by contact with the blood or body fluids of an infected person. It’s deadly somewhere between 25 and 90 percent of the time depending on the strain. Ebola may be carried by bats, researchers think, because when bats are infected with it, they don’t die.

Pubic lice, or ‘crabs’ were given to humans by gorillas. We likely picked up the disease, not by sleeping with gorillas, but by sleeping in gorilla nests or eating the gorillas, scientists concluded in 2007.

Article extracted from Live Science