A Glossary of Ebola Contact Types

Since Ebola made landfall in the US in September, officials at the US Centers for Disease Control and their counterparts at the state and local levels have campaigned to educate the public about how the virus can—and can’t—move from person to person.

The effort has resulted in communiqués about the difference between “casual,” “direct” and “close” contact.

With that in mind, here is a guide to help you stay Ebola-free while maintaining whatever interaction with others you (and they) prefer.

Casual Contact

The word “casual” is fraught with ambiguity.

NYC Mayor de Blasio: Ebola not spread through casual contact; no reason to be alarmed. http://t.co/AsypHTR7eA

— CNN Breaking News (@cnnbrk) October 24, 2014

New York’s mayor, who has talked of “casual contact” at two press conferences in as many days, seems to have borrowed the phrase from the US Centers for Disease Control, which distinguishes casual contact from other forms of connection.

“Everything we have seen in our decades of experience with Ebola indicates that Ebola is not spread by casual contact,” Dr. Thomas Frieden, the CDC’s director, testified Oct. 16 before the US House Energy Subcommittee on Oversight and Investigations.

That’s because Ebola is contagious only when someone starts to show symptoms.

Until then, breathing the air, using public transportation, sharing an elevator or doing the myriad things that require us to interact with one another presents nearly zero risk of infection.

“We think this is not a disease that you can get from simply being next to somebody,” Dr. Jay Varma, New York City’s Deputy Commissioner for Disease Control, told ABC News.

Though body fluids can contain the virus, evidence suggests that sweat tends to harbor Ebola less effectively than substances such as blood, saliva and breast milk. Grazing a carrier’s arm on a summer’s day or sharing gym equipment presents little risk until that person becomes symptomatic.

Hook-ups can be casual—but not in the context of Ebola. Those who recover from the disease can no longer spread the virus. Still, the CDC recommends abstaining from sex for three months, because the virus can survive that long in semen.

RT to share the facts on #Ebola: http://t.co/RMFwal2IB8 #EbolaInNYC pic.twitter.com/IJYNF2Uyp1

— The White House (@WhiteHouse) October 24, 2014

Close contact

A second category of contact covers people who have been in proximity for some amount of time with someone who later shows symptoms of the virus.

That can include an Ebola patient’s friends, family members and fellow passengers. Officials in New York City have quarantined three people close to Dr. Craig Spencer, who on Thursday became the fourth person to be diagnosed with Ebola in the US.

"So we have three individuals. Fiancee and two friends. All well. All quarantined." - Mayor @BilldeBlasio live on http://t.co/10woidEfEd.

— NYC Mayor's Office (@NYCMayorsOffice) October 24, 2014

City officials said that the driver of an Uber taxi who shuttled Spencer to Manhattan from Brooklyn did not come into close contact with the physician and has little risk of contracting the virus.

Close contact also applies to people who enter the US from Sierra Leone, Guinea or Liberia, the nations at the epicenter of the outbreak. The CDC said Wednesday that public health officials will monitor such travelers closely for 21 days. On Friday, the governors of New York and New Jersey said that their states would quarantine anyone who enters the US through Kennedy and Newark Liberty airports who has had direct contact with Ebola patients in those three countries.

Direct contact

According to the CDC, Ebola spreads through direct contact of the eyes, nose, mouth or other openings with blood or bodily fluids of a person who is sick with the disease.

Infection “inevitably tracks back to a significant exposure” with either a very sick person or a dead body teeming with Ebola virus, Dr. Armand Sprecher, a physician with Doctors Without Borders, told reporters at a briefing Wednesday.

That makes the risk greatest to healthcare workers, family members and others who come into that level of contact with sick patients.

Treating Ebola patients can expose healthcare workers to bodily substances and blood, as well as contaminate medical supplies and diagnostic devices.

The CDC recently tightened guidelines for healthcare workers who care for Ebola patients. The polices aim to protect “skin and mucous membranes from all exposures to blood and body fluids during patient care,” the CDC says.