Add camels and fruit bats to the list of animals - ducks, geese, chickens and pigs, for starters - that transmit deadly diseases to humans. And to avian flu and swine flu, add Middle East Respiratory Syndrome (MERS) and the Ebola virus. Both are creating public health havoc - the camel-borne MERS in the Persian Gulf area and the fruit-bat-transmitted Ebola in West Africa. And quarantine may be the only prevention against a wider spread.

Both are deadly. There is no vaccine against either. And both are only a plane flight away from infecting other parts of the world.

The World Health Organization said last week it has confirmed 261 cases of MERS since 2012, most of them in Saudi Arabia, with 93 deaths, about 46 percent. Cases have been reported in Europe, and the current outbreak in Saudi Arabia includes 15 confirmed cases and three deaths. MERS is a coronavirus, similar in some respects from the one that caused a major outbreak of severe acute respiratory syndrome (SARS) in China in 2003. Transmission between persons is by contact, but hospitals in Saudi Arabia are also disinfecting areas where patients have been treated. No known cases have reached the United States, but the U.S. Centers for Disease Control says it is keeping a watchful eye out.

Ebola is an altogether nastier virus, with a death rate on average of 67 percent, and in the case of current victims in West Africa, closer to 80 percent. The World Health Organization reports that from the first outbreak in central Africa in 1976, which happened near the River Ebola - hence the name - through 2012, this virus had infected 2,387 people, of whom 1,590 died.

In the last six weeks an unprecedented new outbreak has occurred in urban centers with greater air access to the outer world. Those include cities in Guinea, with 218 suspected or confirmed cases and 141 deaths as of a week ago; Liberia, with 35 suspected or confirmed cases and at least 6 deaths; and Sierra Leone, with three suspected cases.

The virus causes external and often fatal internal bleeding. About the only effective treatment is intravenous transfusions to replace lost body fluids.

Transmission is by close contact with the infected person, placing family members and health care workers at greatest risk.

Dr. Sanjay Gupta, CNN's chief medical correspondent, reported earlier this month from Conakry, Guinea, that health workers will wait 42 days - two incubation periods - from the last reported case before they can declare that this outbreak is over.

So far no cases have been reported outside Guinea,Liberia and Sierra Leone. And so far the World Health Organization does not recommend travel restrictions to or from these countries.

Nevertheless, the longest recorded gestation period is 21 days, so it would be possible for an infected person to travel long distances before displaying symptoms.

The easy availability of air travel, the severity of these two communicable diseases and the potential for exponential infection are a frightening combination. It is vital that the diseases be contained. And it is more important than ever for world health groups to be vigilant and make sure they stay that way.