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article imageEbola virus in the U.S. and contact tracing technology

By Karla Lant     Oct 2, 2014 in Science
Dallas - Contact tracing allows epidemiologists and others fighting the spread of dangerous diseases like the Ebola virus.Technological tools in surveillance and molecular diagnostics, information and communications, and geoinformatics make this tough job easier.
Thomas Eric Duncan, the first person to be diagnosed with Ebola on American soil, is being treated in a Texas hospital in isolation. He is in pain, and has not been able to eat in a week. Mr. Duncan was infected with Ebola while still in his home country of Liberia, most likely while acting as a good samaritan: he helped carry a woman who was seven months pregnant and convulsing to a hospital in Monrovia, only to have her turned away. This was days before he flew to the U.S.
Upon his arrival in Dallas he was still asymptomatic, which according to all relevant medical authority means he was not able to transmit the disease. As soon as he became ill on September 25th, he went to the emergency room. He honestly provided his travel history, telling a nurse he had just arrived from Liberia. Even so, he was released.
Now Ebola virus is in the U.S., and it is a problem for epidemiologists and contact tracers. Contact tracing is a proven public health method that allows doctors, epidemiologists, and others fighting the spread of dangerous diseases such as that caused by the Ebola virus to prevent transmission and new infections. Its goal is to find every single person that an infected individual has contact with during a period of communicability.
This isn't always easy, but advanced technology helps. Experts identify several technological tools that assist in contact tracing of Ebola-infected people specifically within three areas: surveillance and molecular diagnostics, information and communications, and geoinformatics.
Technological tools within the surveillance and molecular diagnostics category include advanced imaging devices, equipment for specimen collection, and PCR molecular diagnostics equipment. Information and communications tools include the obvious things such as smartphones, tablets, and laptops with wireless access, but also data storage and analysis and a high-capability case contacts database. Finally, geoinformatics tools should include planning equipment for case management strategies, and surveillance equipment that allows for the monitoring of spatial and geographical distributions of contacts.
How does contact tracing with tech play out with Ebola? Contact tracing is far easier in a country like the U.S. than it is in rural areas of Western Africa where the outbreak has been at its worst. Liberia, Mr. Duncan's home country, has been hit hard, with more than 1,800 deaths since the end of September, including the death of the woman he tried to save. Lack of access to critical containment technologies has been a serious problem.
The CDC, WHO, and other public health agencies all promulgate the same protocols for contact tracing. First, public health officials identify every single person that has had contact with the infected person. Everyone in this group is monitored for 21 days; this covers the incubation period of the virus.
If symptoms emerge in any contacts, that person is placed into isolation and tested for the virus. Symptoms include: abdominal pain, diarrhea, high fever, muscle pain, severe headaches, unexplained bleeding, vomiting, and weakness. If any contact does test positive, this sets a new round of contact tracing in motion.
“We outline all the movements that could have occurred from the onset of symptoms,” Dr. Thomas Frieden, director of the Centers for Disease Control and Prevention, said Tuesday in a national press conference. “We always err on the side of identifying more contacts rather than less.”
In practice, public health officials have traced the steps in this case. Thomas Eric Duncan is a 42-year-old Liberian citizen, and was previously a healthy man. He came to the U.S. to visit family. Thus, once he left the hospital, he returned to the home of family members where he was staying.
Each family member, friend, or stranger who came into contact with Mr. Duncan will be traced and observed. Up to 20 people we know of so far, including the paramedics who transported Mr. Duncan and five school-aged children who are his family members, are now contacts under observation. So far none have exhibited symptoms. They are all being monitored at home.
These contacts are all known to public health officials. Their temperatures are being taken twice daily — at least for now, since none of them are displaying any sign of fever. They have given their complete medical histories, and they are cooperating with officials.
Can we trace the Ebola back to where Mr. Duncan was infected? That is unclear as yet. He was screened before boarding his flights as is the protocol now during the Ebola crisis. At that time he was asymptomatic, and therefore passed his screening.
This is obviously not 100 percent effective for preventing all spread of the disease. It is, however, effective at preventing someone who is ill and actively communicable from boarding a plane, however difficult the actual prospect of transmitting it to other passengers on a flight is. In this case there is no chance that Mr. Duncan spread the disease before boarding.
The incubation period for the Ebola virus is between two to 21 days. This means that it might lie dormant inside a person for up to three weeks before he or she has any symptoms or is able to transmit it. There is no way to spread the disease before that time.
People who have Ebola can spread the disease, but it is not “contagious.” It is, instead, communicable, which means that it can be spread, but only through contact with the infected bodily fluids. So it is only through direct contact with the bodily fluids of people who display active symptoms of the virus, such as diarrhea and vomiting, a high fever, abdominal pain, a severe headache, and others, that there is any danger. The Ebola virus is not like the flu virus which can be spread through the air, or before symptoms are able to be seen.
“Ebola doesn't spread before someone gets sick. Ebola does not spread ... from someone who doesn't have fever and other symptoms,” Dr. Frieden said Tuesday.
“This is not an airborne transmission,” said Dr. Marty Cetron, director of the CDC's Division of Global Migration and Quarantine. “There needs to be direct contact frequently with body fluids or blood.”
The Ebola virus itself needs to live inside another organism to survive. It is deadly once it is inside you, but outside your body it is fairly easy to kill. Doctors Without Borders indicates that it can be killed by chlorine, detergent, direct sunlight, heat, and soap.
Medicins Sans Frontiers epidemiologist Kamiliny Kalahne argues that points of contact with Ebola virus are typically very obvious: “People who become sick with it almost always know how they got sick: because they looked after someone in their family who was very sick -- who had diarrhea, vomiting and bleeding -- or because they were health staff who had a lot of contact with a sick patient.”
In the case of Ebola in the U.S., proven public health methods coupled with better access to technology, healthcare, medical personnel, and medications will hopefully win the day.
More about Ebola virus, contact tracing, contact tracing technology, Epidemiology, Science
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