An Ebola patient racked with acute symptoms may shed nearly three gallons a day of highly infectious blood and other body fluids, feces and decomposing tissue. It makes caring for patients suffering from this dreadful disease difficult and dangerous.
As in all Ebola episodes, preventing infection in West Africa during what has been the worst outbreak in history has placed a lot of effort on looking after those dealing with the victims. New high-tech equipment is now available for use by health care workers, but in some countries it may be inappropriate.
The Ebola virus is spread by direct contact, which can be through the tiniest piece of broken skin or via mucous membranes. Protective equipment is needed. But when Nichodemus Gebe, head of biomedical engineering at Ghana's Ministry of Health, started looking for specialist gear he was unable to find any easily transportable treatment units able to contain the virus. Last July, he asked Odulair, a company in Cheyenne, Wyo., if it could help. The firm makes mobile medical clinics.
Two months later Odulair put a modular Ebola-isolation unit on the market. The unit maintains a differential air pressure between rooms to help prevent the virus from spreading; although not an airborne disease, it can attach to particles which drift in the air. A higher pressure is maintained in areas reserved for medical staff and those awaiting diagnosis. The air in each room is purified up to 36 times an hour with filters that trap almost all particles larger than a third of a micron, or three millionths of a meter, which is smaller than the Ebola virus. Air is also zapped with germ-killing ultraviolet light.
The doors in the unit can open automatically, allowing a "telepresence" robot to patrol. It displays live video of a doctor or nurse, allowing them to speak to a patient. The RP-VITA, as the robot is called, greatly reduces the number of times staff must put on protective suits and step inside, says Anita Chambers, Odulair's boss.
But only two Odulair isolation units have been sold. One unit was delivered to a contractor working for America's Department of Homeland Security and the other will soon be sent to Trinidad and Tobago. For poor countries, such equipment is unaffordable, says Gebe. An Odulair unit to house 10 confirmed and eight suspected patients costs about $900,000, robot not included. A Q-10 comes in at around $53,000 and a Xenex robot at some $100,000.
Nevertheless, some new technology is helping in West Africa, where the number of cases has fallen, but the disease is hanging on. The bible on stopping transmission in poor countries was for many years a 1998 report by the World Health Organization and the Centers for Disease Control and Prevention (CDC) entitled "Infection Control for Viral Haemorrhagic Fevers in the African Health Care Setting." It enshrined a "sort of lowest common denominator" realism based on what was widely available rather than most appropriate, says Armand Sprecher, a Doctors Without Borders epidemiologist. It helped to establish surgical garb as the thing to wear.
But clothing designed for operating rooms is not the best for, say, collecting corpses lying in infectious body fluids. Aprons and surgical gowns leave the wearer's back mostly unprotected so, when squatting to lift a body, material on their boots is likely to wet the cotton surgical scrubs on their buttocks and thighs. "That's an uncomfortable feeling," Sprecher says. He began working on Ebola outbreaks with MSF in 2000, several years before coveralls made with a DuPont synthetic fiber called Tyvek became widely available.
Tyvek is produced from high-density polyethylene fibers. These are not woven, as most fabrics are, but "flashspun" in a process that involves the evaporation of a solvent. Although tear-resistant and waterproof, Tyvek does allow air molecules under high pressure to pass through. This has now led to the wide adoption of a more impermeable laminated DuPont fabric called Tychem.
Coveralls made with Tychem, however, have a big drawback. The material restricts gas exchange enough to prevent evaporative cooling, so wearers in hot weather may quickly overheat, becoming confused or even suffering a heat stroke.
In the past decade latex gloves have largely been replaced by those made with nitrile, a synthetic rubber that better resists disintegrating in chlorine disinfectants. Goggles are increasingly designed with ventilation slits not placed on the top, lest sweat or rain wash contaminants into the eyes. And surgical masks are now more widely used because their cost has dropped some 75 percent in the past 15 years, says Juan Martínez Hernández, an epidemiologist and Ebola expert based in Madrid.
Surgical masks, however, lose effectiveness when soaked with sweat. More expensive "duckbill" designs that protrude from the face work better. MSF is field-testing a handful of respirators, which are powered by a battery pack.
Copyright 2013 The Economist Newspaper Limited, London. All Rights Reserved. Reprinted with permission.