In DepthInfectious Disease

Echoes of Ebola as plague hits Madagascar

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Science  27 Oct 2017:
Vol. 358, Issue 6362, pp. 430-431
DOI: 10.1126/science.358.6362.430

Children in Madagascar's capital city wear masks to protect themselves from pneumonic plague.

CREDIT: ALEXANDER JOE/AP IMAGES

As an unprecedented outbreak of plague sweeps Madagascar, health experts see unsettling parallels with West Africa's Ebola epidemic of 2 years ago. Again, a fearsome disease is spreading from person to person, abetted by local customs and a broken health care system. And like Ebola, this outbreak of plague has moved from the countryside to the cities, where it is flashing out of control. “Exactly like Ebola, it is very challenging to contain urban outbreaks,” says Eric Bertherat, a plague expert with the World Health Organization (WHO) in Geneva, Switzerland, which is helping Madagascar coordinate its response.

In contrast with Ebola, plague can be treated with antibiotics, and so far the case numbers are relatively small. As of 20 October, WHO reported that 1297 people in Madagascar had been infected with plague and 102 had died. (Those numbers include confirmed, probable, and suspected cases.) But cases are doubling almost weekly. In the capital, Antananarivo, schools are shuttered and public gatherings banned. Last week, Madagascar's health minister implored health workers not to take vacations. And hundreds of epidemiologists and technical experts are pouring into the island nation, one of the poorest in the world.

Not only is the disease hitting densely populated urban areas, including Antananarivo and the port city Toamasina, but it has taken an unusual and especially menacing form: pneumonic plague, which is spread from person to person through coughing or sneezing. Without treatment, pneumonic plague is 100% fatal, usually within 48 hours. “I don't think any other disease kills so fast,” Bertherat says. “I personally saw a person in the [Democratic Republic of the Congo] get infected in the morning and die that night.”

CREDIT: J. YOU/SCIENCE

Madagascar is one of the few countries still afflicted by plague, the Black Death of the Middle Ages. The disease, caused by the bacterium Yersinia pestis, is endemic in remote areas, erupting during the rainy season and typically infecting perhaps 400 people. These outbreaks are mostly bubonic plague, which lurks in rats and is occasionally spread to humans by fleas. But when bubonic plague is untreated, it can reach the lungs and morph into the pneumonic form, capable of racing from person to person.

That is apparently what happened to the index case, a 31-year-old man with malarialike symptoms who left Ankazobe district in the central plateau on 27 August in a crowded bush taxi that was heading through Antananarivo. He died along the way. Soon, 31 people who were in contact with him directly or indirectly became infected, and four died.

The outbreak didn't come to light until 13 September, 2 days after a 47-year-old woman with respiratory distress died in a hospital in Antananarivo. The Pasteur Institute of Madagascar in Antananarivo, a global leader in plague response, confirmed the cause as pneumonic plague. By then, it had already started its rampage.

One reason the outbreak spiraled out of control is that health care workers in the capital were not used to seeing plague, which starts with flulike symptoms. “There was a delay in diagnosis, so the chains of transmission continued,” Bertherat says. At least 39 health workers have been infected.

Pasteur has distributed thousands of rapid diagnostic tests. The institute confirms each case with the polymerase chain reaction, which takes about 8 hours, and its plague lab is seriously backed up, Pasteur scientists say. All Y. pestis strains isolated so far are susceptible to antibiotics.

International partners have helped set up nine plague treatment centers and isolation wards, but WHO says more are urgently needed as symptomatic people crowd into clinics and hospitals, risking further spread. “You want to make sure a suspected plague case does not walk through the clinic,” says Nyka Alexander, WHO's communications chief in Madagascar. WHO and its partners, among them the U.S. Centers for Disease Control and Prevention, UNICEF, and the European Centre for Disease Prevention and Control, are positioning supplies around the country, including more than 1.2 million doses of antibiotics and 150,000 sets of personal protective gear for health workers.

Disinfection and rat and flea control are key to curbing bubonic plague. But for pneumonic plague, health workers need to find and prophylactically treat everyone who has come into contact with an infected person. WHO has already trained almost 2000 community health workers in Antananarivo in contact tracing, which began 12 October. Of some 2500 contacts identified to date, 66% have been given oral antibiotics. (For confirmed cases, treatment is far more harrowing—40 antibiotic shots given over 7 days.)

Contact with the dead can be risky. But as in the Ebola epidemic, efforts to reduce risk during burials conflict with deep cultural beliefs and traditions such as washing the body and returning it to the person's birthplace, Bertherat says. “If we don't respect [those traditions], we risk that people will hide deaths.”

WHO is also worried that the outbreak will spread beyond Madagascar; it considers nine neighboring countries and territories at very high risk (see map, above). Departing passengers are closely screened at Madagascar's international airport. And technical advisers are helping at-risk countries set up systems for surveillance and contact tracing, and are positioning medical supplies.

To infectious disease experts, the outbreak underscores the lesson of the Ebola epidemic. As cities burgeon and populations become more mobile, once-isolated diseases are increasingly likely to reach cities, where they can race out of control. “Next time,” Bertherat says, “we need to be ready to manage [plague] in an urban setting.”

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