Sunday, March 01, 2015

Eliminating a deadly disease ain't easy


Regardless of the size and effectiveness of the efforts to stop it, Ebola is showing an unwanted resilience to its elimination. The example of Sierra Leone shows just one of the variables that can't be controlled.
It seemed as if the Ebola crisis was abating.

New cases were plummeting. The president lifted travel restrictions, and schools were to reopen. A local politician announced on the radio that two 21-day incubation cycles had passed with no new infections in his Freetown neighborhood. The country, many health officials said, was “on the road to zero.”

Then Ebola washed in from the sea.

Sick fishermen came ashore in early February to the packed wharf-side slums that surround the country’s fanciest hotels, which were filled with public health workers. Volunteers fanned out to contain the outbreak, but the virus jumped quarantine lines and cascaded into the countryside, bringing dozens of new infections and deaths...

In Sierra Leone, the hardest hit of the countries, the decline leveled off in late January, and the country has reported 60 to 80 new cases weekly since then. Guinea has experienced months of lower-level spread. Even in Liberia, where only a handful of treatment beds remain occupied, responders lament that a health care worker who recently became ill might have exposed dozens of colleagues and patients, and that a knife fight had exposed gang members to the blood of a man who tested positive for Ebola.

“I doubt it will stop just suddenly,” said Dr. Pierre Rollin, an infectious disease expert with the United States Centers for Disease Control and Prevention. “It’s always bumpy, and the bigger the outbreak, the more chance you have a bumpy thing.”

As large epidemics taper off, it is common to find new complications in the effort to reach zero cases. “Oftentimes we find surprises when we get to a low level that were hidden by the epidemic itself early on,” said Dr. William Foege, a former director of the C.D.C. and a leading figure in the eradication of smallpox.

For example, health officials managed to reduce measles drastically in the United States in the 1970s, but it took some time before experts realized that a few travelers per week arriving from other countries were developing the illness, continuing its spread. Importation of measles is again a problem today, and it is suspected as a factor in the current outbreak linked to Disneyland.

Then there is polio, which experts had resolved to eliminate globally by 2000, before wars and unexpected resistance disrupted the plan.

“I don’t think we ever foresaw a time when people would shoot and kill polio vaccinators,” Dr. Foege said, referring to incidents in Pakistan and Nigeria that interrupted inoculation campaigns.
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Eliminating smallpox about 35 years ago required a deep understanding of the communities in which it hid. During its last stand, in Somalia, people obscured cases, partly out of embarrassment.

“I think Ebola will turn out to be the same thing,” Dr. Foege said. “The surprises will not be so much scientific as cultural: the ability to hide cases; the desire not to be identified as having Ebola or being in contact with Ebola. Those are the things we have to find out how to overcome.”
Ebola and other diseases may yet see their end, but there are many unexpected roadblocks ahead.

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