In a sunny courtyard of the Evelina Levy School for Girls, hundreds of girls in blue uniforms did their part to rid Haiti of an ancient and reviled disease.
They lined up in pairs to get three pills dropped into their mouths. They swallowed them down with a quarter-cup of water. They got a second medicine, a flavoured tablet, to chew as they walked back to class.
Two middle-aged women treated 12 girls every 2 1/2 minutes, one pouring the water and the other shaking out the pills. Another woman ticked the columns for age, sex and drug on a white form with a green pen.
"Mass drug administration" is easy if your target is elementary school students. It's harder when you want to reach nearly everyone else in a country of 10 million people.
That is the goal Haiti set this year in its campaign against a parasitic infection called lymphatic filariasis that is present in 80 per cent of the country. Spread by mosquitoes, in severe cases it leads to permanent swelling of an arm or leg. That condition, called "elephantiasis", can be grotesque and life-changing. In men, the worms can cause a swelling of the scrotum that is even more stigmatising.
Lymphatic filariasis is a "neglected tropical disease", the name for a group of maladies that have disappeared from industrialised countries or never existed there. Others include onchocerciasis ("river blindness"), schistosomiasis ("snail fever"), soil-based intestinal worms, and the eye infection trachoma. For 1.9 billion people, most of them poor, they are still threats.
Eliminating the diseases has been an object of intense effort and research over the past decade. The work is largely unknown outside the global health community, overshadowed by higher-profile campaigns against AIDS, malaria and tuberculosis.
In 2010, 484 million people worldwide took drugs against filariasis - more than for any other neglected tropical disease but still only one-third of the people at risk for it.
"You could argue it's the world's largest public health programme," said Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine in Houston.
Most of the neglected diseases can be cured in their early stages with drugs taken once or twice a year.
Pharmaceutical companies are donating drugs for mass administration. A bonus is that some treat more than one infection.
Ivermectin, donated by Merck, cures river blindness and filariasis. Albendazole, donated by GlaxoSmithKline, gets filariasis and intestinal worms. Some subsidiary effects are only now being discovered. When ivermectin was distributed for river blindness in Senegal, it reduced malaria transmission. When azithromycin (provided by Pfizer) was distributed twice a year to Ethiopian villagers for trachoma, childhood mortality fell 50 per cent.
"What's that all about? That's the US$64,000 question," Hotez said.
Congress began earmarking money for mass drug administrations in 2006, and in 2008 President George W Bush announced a five-year programme to fight neglected tropical diseases. This year, the United States will spend US$89 million on them - roughly 10 per cent of the Obama administration's global health budget.
After years of mass drug administrations, nine countries - Burundi, Cape Verde, Costa Rica, Mauritius, Rwanda, Seychelles, the Solomon Islands, Suriname, and Trinidad and Tobago - were declared free of lymphatic filariasis in 2011 by the World Health Organisation. Haiti hopes to join them.
Until the earthquake of January 12, 2010, Haiti and its foreign donors fought the disease only where it was most prevalent. Over time, more and more parts of the country were included in the campaign. However, Port-au-Prince, a place where the disease was uncommon, was always judged out of reach. The capital was simply too crowded and chaotic for mass drug administration.
Ironically, the earthquake changed people's minds about what was possible - and necessary.
One-third of Haiti's population was affected by the quake. More than 2 million people became homeless or chose to move. Internal migration threatened to redistribute the disease, interrupt the every-year treatment for many people, and generally undo all the gains of the previous decade.
At the same time, the earthquake brought a flood of money and human energy to Haiti. Suddenly, nationwide drug administration - including in Port-au-Prince - became just one more ambitious task that had to be done.
"There was this feeling that we just couldn't quit. Things had come too far to walk away," said Patrick Lammie, a scientist at the US Centers for Disease Control and Prevention (CDC) who has worked on filariasis in Haiti for more than two decades.
As a consequence, for four weeks this past winter, two medicines - albendazole and diethylcarbamazine (DEC) - were handed out in Port-au-Prince's schools, markets, churches, factories and public places. They were also delivered to the squatter camps where more than a half-million earthquake-displaced people still lived. In all, about 70 per cent of the capital's population took them, according to a CDC survey in the spring.
Today, more than two years after the earthquake, "everyone in Haiti has gotten the drugs", Lammie said. (The actual estimate is 8.7 million). "That's the success story of Haiti. Now we have to do it on an annual basis."
The rationale for such an ambitious effort is this: Albendazole and DEC kill off the larval form of the filariasis parasite, which if not treated matures into an unkillable worm in about a year. If an entire population takes the drugs regularly - adults once a year, children twice - the amount of parasite larvae circulating in people and mosquitoes falls so low that no new transmissions occur.
Biologists think that 70 per cent coverage for eight years is enough to stop new cases, assuming the same people are not missed year after year. If they are, those people can become a permanent reservoir from whom mosquitoes can pick up the parasite and pass it on to new victims through bites.
Haiti will know by the end of the decade whether it has pulled the trick off.
In Haiti, the government's health ministry is doing most of the work. Two charities, IMA World Health and RTI International, provide advice, along with the University of Notre Dame. A foundation associated with the drugmaker Abbott Laboratories is helping with salaries.
The target in a mass drug administration may be the whole population, but that does not mean you can take your eye off the individual. Abdel Direny, the 39-year-old Haitian physician in charge of the campaign in Jacmel, knows that.
After assuring himself that the drug distribution at Evelina Levy School was going well, he drove to another school. What he found was a platoon of volunteers in campaign T-shirts helping teachers pass out pills. The students, high school girls, were being told to take the medicine when they got home. The city water supply to the school was not working that day, and nobody had brought bottled water as backup.
"They're not supposed to do that," Direny said to Edgar Isidor, a community leader in a porkpie hat who came along to enhance the doctor's authority. "The pills are supposed to be poured into their mouths."
To much consternation, Direny stopped the drug distribution and ordered it rescheduled for the next day. Just as the principal was finally persuaded, somebody rolled a wheelbarrow full of blue five-gallon water jugs into the school's courtyard. But it was too late.
How much difference can some missed mouths make?
In 2000, about 15 per cent of the 150,000 people in the commune of Leogane, west of Port-au-Prince, had microscopically visible parasites in their blood. (Communes are like counties; Haiti has 140 of them). After six years of mass drug distribution, that was down to less than 1 per cent — a level that if maintained for a decade would have stopped the disease altogether. Civil unrest, however, prevented drugs from being handed out in the seventh year.
Filariasis roared back. By 2008, the prevalence of infection was up to 4.6 per cent. More troubling, a survey found that 24 per cent of people said they had never taken a pill against the disease - and thus were probably a hidden reservoir for it.
The lesson: Every mouth counts.
Mass drug administration is the main tool against lymphatic filariasis. But it is not the only tool. In an industrial park in Port-au-Prince, a theoretically easier way to rid the country of the parasite is under way.
The Reverend Jean Michelet Dorescar, a Catholic priest, runs a factory that fortifies salt with DEC, one of the two drugs used in the mass campaigns. Eating that food additive year after year will kill off filarial larvae in an entire population. China used the strategy (which was invented by English biologist Frank Hawking, father of cosmologist Stephen Hawking) to eliminate filariasis in the 1980s.
The Haitian government has not mandated the use of medicated salt. The factory's product, subsidised by charities, must compete with plain salt evaporated from seawater and sold by the handful in Haiti's markets. Fortified salt, promoted heavily in Guyana a decade ago, never really took hold.
Dorescar knows his salt must look good and taste good, first and foremost. He has a hard time finding high-quality salt from Haiti. He recently bought a load from Jamaica and was disappointed by it, too.
"When I opened the bag I was very surprised to see the stones," he said.
He stood next to a table covered with bright white salt. Four men were picking out pieces of gray gravel by hand.
The factory is owned by Haiti's government but operated by the University of Notre Dame, which along with other donors subsidises the product. Last year, it sold 71,000 pounds of treated salt to markets in the three communes with the most filariasis.
A survey is under way to see whether the rate of filariasis infection has changed in the places where people stir it into their rice and beans.
- Washington Post