Epidemiologists Speak Out About The Transmissibility Of Ebola And
Adequacy Of Control Measures
CDC Director
Sees Positive Developments In Controlling Ebola But A Long Hard
Fight Ahead
“Transmission I
think is the ultimate boogey man in the United States for a lot of
people,” said one reporter at a CDC press conference characterizing
the dramatic increase in the level of US public concern or anxiety
about the transmissibility of Ebola. Dissecting this public concern
in greater detail, Columbia University epidemiologist Abdulrahman
El Sayed told New York Magazine “Ebola’s the kind of disease
that zombie movies are made out of…It’s the kind of thing where if
you’re notclose to the science and don’t understand the epidemiology
of it, it’s a very scary-sounding disease — you bleed all over the
place, it kills more than 50 percent of the individuals who contract
it, it’s spreading like wildfire in West Africa.”
The increase in public concern follows the occurrence of the first
imported and spread cases in Dallas Texas, and the first spread case
in Europe in a Spanish nurse who cared for anEbola
patient. These US and European experiences reveal potential
inadequacies or shortcomings in airport screening programs or
breakdowns in the recommended safety protocols for handling infected
persons in hospitals. With public alarm running at high levels, the
US has announced it will begin screening at selected US airports and
providing additional training to hospital staff.
Epidemiologists On
The Spot
Epidemiologists
seemingly everywhere are being asked about the disease, the risks it
may pose, and the adequacy of control strategies. The answers have
in some cases been encouraging and reassuring while other statements
have raised concerns even further.
Robert Haley,
chief of epidemiology and professor of internal medicine at UT
Southwestern, played down the risk of spread to the general public
in a radio interview in Dallas. “I don’t know if we can limit it to
one case because his family, the people who were in the home with
him over the last several days before he came in, they are at grave
risk…There may be some additional cases in the family but they are
now under quarantine or surveillance by the local health department.
If any of those become ill, they’ll be carefully controlled. So it
won’t spread beyond them…There could be an ER person or maybe an
ambulance driver who would possibly come down with it. I would be
very surprised because our hospital workers and paramedics are very
well trained to protect themselves. If they develop fever they will
immediately go to hospital and not be infectious to others.”
[Ed: This has now occurred in Dallas with the first spread case to a
nurse].
More Reassurance
Oklahoma state
epidemiologist Kristy Bradley said “We do understand it’s a
scary disease…But we want people to understand it’s not spreading
anywhere in the United States…The likelihood that anyone in Oklahoma
would be exposed is not very high…If an Oklahoman did not travel to
Liberia, Guinea, or Sierra Leone and come into contact with a person
who has Ebola, they have a very low risk.”
The Good News
CDC Director Thomas Frieden told the press on October 7 there
are real signs of progress in controlling the outbreak both in Texas
and in other parts of the world. He said the teams in Dallas
carrying out contact tracing and monitoring are doing “a terrific
job dealing with what is really an unprecedented situation”. In
Liberia, he recounted the example of one district which had been at
the epicenter of the outbreak and where cases have now plummeted
possibly due to an increase in the number of isolation beds and
changes in burial practices. “So even in West Africa, even in a
place that [was] at the heart of the outbreak, there are signs of
progress, ” said Frieden.
On October 13 after announcing the spread case in
Dallas, Frieden reiterated that "we know how to stop Ebola" and he
is confident we will stop Ebola in the US.
Halting Spread In Africa
Likewise, a report
from the World Health Organization about the interruption of Ebola
transmission in Telimele district of Guinea provides an example
local success in halting spread. Some of the interventions carried
out were creating a treatment center close to the population,
obtaining WHO experts to provide technical support, constituting a
local crisis committee which delivered one strong message—come
early for treatment you survive; you come late—you die, and
allowing loved ones to talk to patients from a distance. Also
religious and traditional leaders worked together to quell rumors,
and a contact tracing team on motorbikes cruised throughout the
district. The mortality rate locally was 38% which appears to be
much lower than in other parts of Guinea, and cases have ceased in
the area while continuing elsewhere in Guinea.
Success in Nigeria
and Senegal
Also encouraging are the reports from Nigeria and Senegal which each
had imported cases. According to WHO, both countries faced many
difficult challenges yet now have achieved good prospects for
success. No new cases have been reported for almost 6 weeks which is
the time period required to be considered disease free (2 times the
21-day incubation period).
The Bad News
Other
epidemiologists provide less encouraging assessments. A NEJM paper
on September 23 concluded that “the current epidemiologic outlook is
bleak. Forward projections suggest that unless control
measures—including improvements in contact tracing, adequate case
isolation, increased capacity for clinical management, safe burials,
greater community engagement, and support from international
partners—improve quickly, these three countries [Liberia, Sierra
Leone, and Guinea] will soon be reporting thousands of cases and
deaths each week…” They add that there is the possibility that Ebola
could become endemic in West Africa and this prospect calls for
“forceful implementation of present control measures.”
Ebola Is Winning
Other voices
continuing to raise alarm include that of Doctors Without Borders.
Its international director told the UN in late September “…the
promised surge has not yet delivered…Fear and panic have set in, as
infection rates double every three weeks. Mounting numbers are dying
of other diseases like malaria because health systems have
collapsed…Today, Ebola is winning.”
Admitting Defeat in
Sierra Leone
A
discouraging news report in the NY Times on October 10 described the
situation in Sierra Leone where a decision had been taken to
distribute kits to help families tend to patients at home because
the treatment centers are overwhelmed and cannot meet the need. A
similar distribution effort was planned for Liberia where even more
people are dying from the disease, according to the Times report.
Modern Tragedy
Epidemiologist Mike Osterholm from the Center for Infectious
Disease Researh and Policy has written on September 30 that “Ebola
is spreading faster than anyone would like to admit, and the current
slow international response to the deadly disease is morphing into a
modern tragedy…The truth is that we are failing miserably at
containing Ebola…
Slow Speed Response
The essence of
criticisms is not with the control strategy but with the slow speed
of the response which has so far not been rapid enough to get ahead
of the virus. A worst case scenario is that the outbreak will remain
out of control long enough to spread even further to other countries
and create even more of a catastrophe. According to Osterholm, an
international coordinated plan to respond to this even greater
potential outbreak is needed as are urgent efforts to produce
millions of doses of a vaccine that could be administered broadly in
Africa. He called for mobilizing people and resources on a massive
scale. ■
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