In Bangladesh, A New Way to Fight Cholera

Anita Ashfaqunnesa skips over a ditch oozing with raw sewage, her spotlesswhite shawl trailing behind her like a superhero’s cape, then squeezesbetween shacks built on an old rubbish dump. Three years ago, she explains,this slum in northern Dhaka didn’t exist. But with hundreds of thousands ofrural job-seekers pouring into Bangladesh’s capital every year, it now teemswith families, and the water they use for drinking, cooking and bathingcomes from pipes that run alongside, and often through, the sewage ditches.That’s why the area’s oldest living resident is not a person, but a disease.”Cholera is a common ordeal here,” says Anita, 33. “People don’t fear it,but they are happy to hear there’s a vaccine coming to prevent it.”

Anita is one of a small army of field workers collecting household data forthe biggest oral cholera vaccination program in history. It starts on Feb.17 and will involve 240,000 residents in Mirpur, the district that reportsmost of Dhaka’s cholera cases. Two-thirds of them will receive two oraldoses of a cheap new Indian-made vaccine. “We think of it as a demonstrationproject rather than a trial,” says Dr. Stephen Luby, Bangladesh countrydirector for the U.S. Centers for Disease Control (CDC). “We don’t have abig question in our minds over whether this vaccine is going to preventcholera. What we’re trying to do is illustrate the feasibility of using itas a public health intervention.”

(See TIME’s video on the slums of Dhaka.)

Mass vaccination could be a new weapon against an old disease. In Zimbabwe,where cholera claimed 5,000 lives in 2008 and 2009, a swift vaccinationprogram could have cut the death toll by 40%, calculated the authors of astudy published in Jan by PLoS Neglected Tropical Diseases. Such results areavidly followed in Haiti, where cholera has killed about 3,800 people andsickened 189,000 since October. A committee that includes experts from theCDC and the World Health Organization (WHO) recently recommended asmall-scale cholera vaccination project. This rankled Haitian healthofficials, who want millions to be protected against a disease that foreignpeacekeepers almost certainly brought with them after last year’searthquake.

Nobody in Bangladesh disputes the origins of the disease. The Ganges delta,which India and Bangladesh straddle, is cholera’s homeland. Six of the sevenpandemics since the 19th century have originated here. Every year, WHOestimates, there are 3-5 million cholera cases and up to 120,000 deathsworldwide. Dhaka’s dilapidated water and sanitation systems provide idealconditions. Bounded by rivers that are too filthy to purify, the city pumpsup nearly all its water from hundreds of deep wells. It is never enough,especially when those pumps need electricity to run, and Bangladesh isplagued by power shortages too. With no positive pressure in the waterpipes, sewage and other contaminants easily leak in.

The only thing Dhaka doesn’t lack is people. With 13 million residents andcounting, it is a fast-growing megacity in the world’s most denselypopulated large country. New arrivals squeeze into already overflowingslums, or squat on wasteland with zero infrastructure. “Wherever there ishuman misery you will find cholera,” says Dr. Mark Pietroni, MedicalDirector of the International Centre for Diarrhoeal Disease Research,Bangladesh (ICDDR,B) in Dhaka, which is implementing the vaccine projectwith the Bangladesh government. “It thrives on malnutrition, overcrowdingand poor hygiene.”

(See a brief history of cholera outbreaks.)

Cholera outbreaks in Dhaka are as predictable as the seasons. There are twoeach year: roughly one before and one after the monsoon. Dhaka Hospital atthe ICDDR,B treats thousands of cholera patients, who during outbreaks notonly crowd its wards and hallways, but spill out into tents in the parkinglot, forming what might be the world’s only hospital ward with speed bumps.Left untreated, cholera can kill in hours. But treat it promptly andproperly, mainly with oral rehydration salts, and death rates are under 1%.At Dhaka Hospital, even the sickest patients make near-miraculousrecoveries; arrive with just one breath, say locals, and you’ll leave alive.

But as Dhaka’s population grows, so does the hospital’s patient load. EveryMarch and April, a thousand new patients a day is standard. “Cholera is adreaded illness because of its rapid onset, severity and potential to causeoutbreaks that easily overwhelm public health systems,” says Dr. ReginaRabinovich, director of Infectious Diseases at the Bill & Melinda GatesFoundation. “That’s why it’s important to invest in the development of new,more effective vaccines.”

Enter Shanchol, a two-dose vaccine produced by Shantha Biotechnics ofHyderabad and developed with funding from (among others) the GatesFoundation, which also gave $16.5 million to the ICDDR,B for the choleravaccine project. Shanchol is safe and efficacious: a trial in the Indiancity of Kolkata involving nearly 70,000 people showed that the drug gave 67%protection for at least 2 years. Just as importantly for mass vaccinations,it is cheap: its two doses cost about $3, or about a tenth the price of itsonly rival, the Dutch-made drug Dukoral. Shanchol is expected to get WHOapproval this year.

(See the top 10 terrible epidemics.)

Bangladesh’s state-run immunization programs are widely trusted, sopersuading a cholera-weary populace to take the vaccine shouldn’t be hard.Some 80,000 adults and children will receive it; another 80,000 will receivethe vaccine, plus active encouragement to treat household water and washtheir hands with soap. But assuaging those who don’t get it might betrickier. This includes 80,000 people who will unknowingly receive aplacebo, forming a control group that helps validate the project’s results.”That’s what we perceive is going to be our biggest problem: not everybodygets it,” says Luby, who was seconded from the CDC to head the ICDDRB’sProgram on Infectious Diseases and Vaccine Sciences.

One of the project’s broader aims is to get a better idea of cholera’smortality rate. “Right now most of the estimates that people throw aroundare quite speculative,” says Luby. Mortality at the ICDDR,B’s hospital maybe less than 1%, but some patients are dead on arrival — negotiating this vast city’s gridlocked streets can use up precious hours — and others expire at home.

Mass vaccination has its critics. Today’s drugs do not offer long-termcoverage or protect against every cholera strain. And even a cheap vaccine,in high quantities, is expensive and could divert resources from the onlything proven to eradicate cholera: improved water and sanitationinfrastructure. (London suffered centuries of cholera epidemics until theVictorians built sewers.) Improving Dhaka’s infrastructure is vital, agreesLuby, but the task could take decades. The same is true for hundreds ofcities in our rapidly urbanizing world, and indeed for disaster zones suchas Haiti. While that infrastructure is being built or rebuilt, how do youprotect a vulnerable population from cholera? Mass vaccination is oneanswer. “What we’re trying to do is generate some evidence on what’sfeasible and cost-effective,” he says.

Participants in the Mirpur project will be monitored for years. But thevaccine’s impact could be felt as early as March or April, when the moresevere of Dhaka’s biannual epidemics strikes. “That’s why we’re aiming tohave this community immunized by the time that worst peak comes,” says Luby.Haiti — and the rest of the world — will be watching.

See pictures of scenes from Haiti’s cholera outbreak.

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