A Turning Point for Ebola? Possible Reinfection?

Larry Hand

October 23, 2014

Although the global response to the Ebola virus outbreak in West Africa has been too slow and too small, this week may be a critical time in turning the tide, one expert says.

However, as a sign of how serious the Ebola epidemic is, other experts say that someone who is infected with Ebola virus and gets treated successfully may not be completely clear of the disease.

"Our ability to work out what to do in a decisive, well-coordinated manner lags well behind where it needs to be in the 21st century," Jeremy Farrar, MD, PhD, from Wellcome Trust, said during a webcast presented yesterday by the New England Journal of Medicine. "This week will be the week we look back on...where we got the coordination, the leadership."

Dr Farrar was one of six experts to speak during the webcast that spanned the topics of the route of transmission, environmental factors, possible novel therapeutics, restriction of flying, and history, impact, and extent of the epidemic.

He based his optimism on the stepped-up response by the United States, World Health Organization (WHO) efforts, United Nations efforts, and the pending responses by other countries such as China and Cuba.

Going forward, he said, a combination of classic public health practices, isolation of suspected and confirmed Ebola cases, and respect for the dignity of people in the most affected areas can help build a "robust, ethical framework and within a social context."

Reinfection, Reemergence Unknown

In response to a question from a webcast participant, experts discussed the possibilities of reinfection and reemergence of disease after initial clearance.

"We know that patients who have survived do have specific antibodies in their blood," said Armand Sprecher, MD, from Médecins Sans Frontières. "Of course, what we don't know is the threshold at which antibodies give you a surrogate marker of protection. It's possible we may gather that over the course of this epidemic, as we hopefully move toward vaccination."

Paul Farmer, MD, PhD, from Partners in Health, Boston, Massachusetts, added, "In Monrovia, a couple of children under 5 who had negative [polymerase chain reactions (PCRs) after treatment] then returned some weeks later with positive PCR.

"These are children who had a normal course of illness...and had a clinical recovery, and both of these children became ill in a day or two," Dr Sprecher continued. "They came back and were found to be febrile and [PCR-]positive again. Both children had some neurologic signs. The feeling amongst the virologists is...the virus gets into some parts of the body with immunologic protection, like the central nervous system. The immune response clears the virus from the periphery, the patient has a clinical recovery, while the viral infection progresses in the [central nervous system] and eventually returns and reemerges as a renewed positivity. At least one of the children became negative again."

Transmission Route Is Understood, Experts Say

"The vast evidence that we have is that the overwhelming route of transmission is through contact with contaminated fluids with broken skin or mucous membranes," said Arjun Srinivasan, MD, from the Centers for Disease Control and Prevention (CDC). "There can be splashes that are involved, given the significant amount of diarrhea, the severe vomiting, but the issue of aerosol transmission is not thought to be an important route of transmission."

He continued, "The route that we need to protect against, most importantly, is contact with this infectious material, although the use of respiratory equipment would prevent that transmission in the healthcare setting."

As far as possible environmental exposures to Ebola virus, officials are not concerned, said Matthew Arduino, DrPH, from the CDC. "If there were significant airborne transmission we would see spontaneously generated cases that were not linked to a known case. There would be casual transmission."

New Cases 5000 Per Week in December

Christopher Dye, DPhil, from the WHO, said the index person for the current epidemic was identified on December 26, 2013, as a boy living in a wooded area who may have gotten the infection from a bat. The first recognition that this epidemic was truly dangerous, however, did not come until June 2014, when officials determined that this is an epidemic like none seen before.

At that time, the cases started doubling every 2 to 4 weeks, and the current number of cases hovers close to 10,000. He said 5000 cases a week are expected by early December for this "extraordinarily large-scale" epidemic, and "no country is safe."


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