The early symptoms of an Ebola infection include fever, headache,...

The early symptoms of an Ebola infection include fever, headache, muscle aches and sore throat. It can be difficult to distinguish between Ebola and malaria, typhoid fever or cholera. Only in later stages do people with Ebola begin bleeding both internally and externally, often through the nose and ears. Credit: AP

An experimental medication with no discernible track record was administered last week to two Americans who were whisked home from the epicenter of the West African Ebola outbreak.

The drug, developed through a technologically advanced technique, was identified only in January as a potential treatment for the viral infection now sweeping through four African nations.

In the absence of clinical data, no one knows with certainty how well the cloned medication works. There is nothing else in medicine's arsenal to combat Ebola, a problem that applies not only to that disease but an ever-growing list of emergent infections. Few, if any, treatments exist for contagious conditions smoldering in global hot zones:

Exotic forms of flu in China and Southeast Asia.

A respiratory illness with high mortality in the Middle East.

Lassa fever, a West African hemorrhagic viral infection.

Chikungunya fever virus, once relegated to East Africa, but now an epidemic in the Caribbean and recently established in Florida.

Old diseases in new places: dengue fever and West Nile.

No vaccines or medications exist to treat any of them.

"We need to spend time studying emergent infections with an eye toward developing antimicrobial medications and vaccines," said Dr. Janet Hearing, an associate professor of molecular genetics and microbiology at Stony Brook University's School of Medicine.

Exotic infections are no longer relegated to remote parts of the world. Virtually any infectious agent is just an air flight away, Hearing and other experts say.

"The interconnected nature of our world today makes the Ebola virus a greater threat internationally than it might otherwise be," said Dr. Bruce Hirsch, chief of infectious diseases at North Shore University Hospital in Manhasset.

Although officials from the Centers for Disease Control and Prevention said last week chances were minuscule that Ebola would make it into the United States, the agency was hot on the trail of another West African pathogen earlier this year.

CDC documents from this spring describe an all-out effort to trace the movements of a Minnesota resident found to be sick with Lassa fever contracted while traveling in West Africa.

The traveler arrived in Minnesota via Kennedy Airport, according to federal health officials. Disease detectives fanned out in airports in both states searching for people the passenger might have encountered. Fellow airline passengers were also contacted.

More Lassa fever cases

Viral and deadly, Lassa causes a severe hemorrhagic fever similar to Ebola, although each is caused by pathogens belonging to vastly different viral families. There has been an uptick in Lassa fever in parts of Africa this year. The death rate can reach 50 percent in hospitalized patients.

Like Ebola, the Lassa pathogen -- in its later stages -- can cause severe internal bleeding visible in the infected as hemorrhaging from every bodily orifice. There is no effective therapy and no vaccine.

The Minnesota case is the seventh known Lassa occurrence in a returning U.S. traveler. The last one was reported in Pennsylvania in 2010, CDC data show.

While Lassa is endemic in the same countries where Ebola is common, other regions of the world are incubators of different infections.

On May 2, an Indiana man returned home after a stay in Saudi Arabia and tested positive for the virus that causes a newly emergent infection called MERS -- Middle East respiratory syndrome. Nine days later a second MERS-infected U.S. passenger arrived back in this country, this time in Orlando, Florida.

MERS has been percolating in Saudi Arabia since 2012 and is triggered by a virus belonging to the same broad family of pathogens -- coronaviruses -- that ignites SARS, severe acute respiratory syndrome.

SARS emerged in China in 2003, affecting more than 7,000 people and killing more than 750 of them. The virus was transported to Canada by infected airline passengers. An estimated 251 Canadians contracted the infection and 44 died. About 27 people in this country also developed SARS; all survived.

As a coronavirus, MERS shares a transmission feature with SARS that makes it highly transmissible: Either infection can be conveyed through aerosol droplets -- coughing and sneezing. Both Lassa and Ebola are more difficult to contract. The Lassa virus is transmitted to humans when food or household items are contaminated by rodent excrement. Ebola virus is spread through close contact with an infected person.

MERS has killed more than a third of the people in Saudi Arabia who've become infected, the World Health Organization has found.

Unlike Ebola, for which a vaccine and medication are under study, there is nothing in the pipeline to combat MERS.

The Indiana patient was treated in a hospital isolation unit but was released within days after doctors concluded the patient had dramatically improved, said Dr. David Swerdlow, the CDC's lead medical officer on the MERS investigation.

MERS isn't the only viral condition that has arrived in the United States unexpectedly. The perfect storm occurred recently in Florida when the tropical chikungunya virus found its way into mosquitoes.

A Florida man last month, according to the CDC, tested positive for chikungunya fever. This highly debilitating illness, which causes a relapsing arthritic-like joint pain, has swept through the Caribbean and parts of South America since late last year.

Chikungunya on Long Island

Doctors at North Shore University Hospital in Manhasset also have diagnosed the infection in Long Islanders who have returned from travel abroad.

Hearing, the molecular geneticist and microbiologist at Stony Brook, said the two mosquito species capable of transmitting it are well-established in the United States.

Virus trackers also have their eyes on a relatively new strain of flu virus, avian influenza A, or H7N9, that emerged in China last year and is associated with infected poultry. Evidence suggests limited person-to-person spread so far in rare circumstances, according to WHO. The first case outside of China occurred in Malaysia in February.

An older avian strain, called bird flu, or H5N1, has been in circulation since 2003 and has now been detected in 15 countries. In January, a human infection was found in Canada. The strain has a 60 percent fatality rate.

Ebola, nevertheless, has captured the international spotlight.

The CDC last week announced it was deploying teams of health care workers in the African nations where the infection is spreading.

Affected countries include Guinea, Liberia, Nigeria and Sierra Leone. Out of more than 1,700 cases, nearly 1,000 people have died. "This is the biggest and most complex Ebola outbreak in history," said CDC director Dr. Tom Frieden. "Far too many lives have been lost already."

He doesn't see the task ahead as simple, and treatment will have to rely on some of the oldest techniques in public health: barrier protection, such as head-to-toe protective gear for health care workers and quarantine for patients. Isolation was used at the beginning of the 20th century to stabilize outbreaks of cholera, smallpox and typhoid fever.

"It will take many months, and it won't be easy, but Ebola can be stopped," Frieden added.

Yet even though U.S. disease detectives are headed to West Africa, they will not bring with them the cloned drug, ZMapp, developed by the San Diego biotech company, MappBiopharmaceutical. The drug was administered to both Americans who contracted Ebola in West Africa and later were admitted to an Atlanta hospital.

The company, founded in 2003, is developing the medication in cooperation with the U.S. Defense Department and the Public Health Agency of Canada, according to MappBiopharmaceutical's website.

The medication is called a "humanized" monoclonal antibody produced in tobacco leaves.

A monoclonal antibody is a cloned protein, the product of a single cell, and its production is usually ramped up in a living cellular milieu. In the case of ZMapp, that milieu is tobacco leaves. Final product yields, as with any monoclonal antibody technology, are small. Antibodies deactivate viruses.

A team of bioethicists is soon to convene and weigh arguments about using the untested medication in the Ebola outbreak.

Infectious disease expert Dr. Peter Piot, director of the London School of Hygiene and Tropical Medicine and co-discoverer of the Ebola virus, said in a message to students and alumni Friday morning: "This epidemic is now so extensive that we can expect it to last for some months. That means the West must fast-track safety testing of drugs and vaccines."

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