Cross-Species Diseases to Watch Out For

Researchers in California have found that sleeping with, kissing and being licked by your pet can make you sick. It turns out that there's quite a long history of diseases passing between humans and animals.

For starters, lice came to humans courtesy of our cousins, the gorilla. Scientists estimate that the transfer occurred about 3 million years ago.

The human respiratory syncytial virus (HRSV) and human metapneumovirus (HMPV) have been responsible for decimating the chimp population in a section of West Africa between 1999 and 2006. For more, click here.

The ebola virus is believed to be transmitted by infected bats. The virus continues to live even after the animals die. Originally, the threat was confined to gorillas and chimps but ebola outbreaks have also proved deadly during the several outbreaks documented since the 1970s.

It turns out that humans are responsible for giving ulcers to big cats, like tigers. In 2006, a study found that microbes responsible for ulcers in humans, spread to large felines thousands of years ago - likely when a big cat feasted on the remains of a dead body.

Mosquito bites are responsible for spreading malaria and dengue fever.

The Black Death wiped out an estimated 75 million people during the 14th century. The plague - a bacterial disease generated by Yersinia pestis - was found in blood of fleas that traveled with host rats.

A cat-borne parasite called Toxoplasma gondii has been found to make some humans more prone to certain types of neurotic behavior.

A harbinger for our times? Between 1918 and 1919, an influenza pandemic swept the world, killing between 20 million and 50 million people. Most people died because of bacterial pneumonia following influenza virus infection. Though Swine Flu has remained in check, there still remains no antidote.