In Haiti, the body blows just keep coming. About 200,000 died in the January earthquake. Then the recovery was hampered by poverty, an ineffective and corrupt government, and a long tradition of class antagonism and social chaos.

And now Haiti is stricken by a cholera epidemic that has already killed about 1,300.

Cholera is a fast-moving bacterial disease that causes intense diarrhea and can kill within hours. Despite efforts to contain it, Haiti’s epidemic is spreading from its epicenter north of Port au Prince, the capital, and has reached the vast tent cities that still house earthquake survivors.

In cholera, the Vibrio cholerae bacterium multiplies in the intestines, forcing the patient to release vast quantities of highly infectious watery stool. Lacking proper disposal and treatment, the diarrhea can pollute drinking water and start new infections.
Cholera is vanishingly scarce in the developed world, and cholera thrives on poverty, disorganization and under-development.

Photo: PAHO

Drinking water contaminated with the cholera bacterium is the major cause of new infections. The Artibonite river, a source of drinking water for many Haitians, is suspected to be transmitting the cholera epidemic.

Haiti, where cholera had not been seen for a century, has been rocked by controversy about the source of the bacterium. Some angry Haitians blame United Nations peacekeeping troops for bringing it from Nepal, but at this point, treating patients and providing clean drinking water seems more pressing than doing genetic forensics to track the disease to its origin.

From the viewpoint of V. cholerae, chaotic, post-earthquake Haiti may be paradise, but outbreaks have also occurred in Latin America, Africa and India in recent years. The World Health Organization estimates that cholera annually infects three to five million people and kills 100,000 to 120,000.

Prompt treatment with electrolytes dissolved in clean water can prevent death in 99 percent of cases.

A violent announcement

Cholera announces itself with a sudden, violent outbreak of diarrhea – a “rice-water stool” named for its semblance of water used to cook rice. Diarrhea — and sometimes vomiting — can cause massive water loss and electrolyte imbalance. Muscles cramp and eyes recede into the skull.

Falling blood pressure and oxygen starvation cause a state of shock that can kill within minutes. A graphic description of cholera is mortifying: “A mid-nineteenth-century English newspaper report described cholera victims who were ‘one minute warm, palpitating, human organisms-the next a sort of galvanized corpse, with icy breath, stopped pulse, and blood congealed-blue, shriveled up, convulsed.’”

Saint Nicolas Hospital, St. Marc, Haiti; PAHO

Haiti’s hospitals, like this one north of Port au Prince, are being tested by the cholera outbreak, but most patients can be treated at an early stage with oral rehydration salts.

An incubation period as short as two hours is one reason for cholera’s dreadful reputation, but its efficient spread through contaminated water is another. As Haiti demonstrates, the conditions of poverty, filth and social chaos that help spread cholera also hinder prevention and treatment efforts.

At present, health organizations in Haiti are focusing on sanitation, clean water, hand washing, and other tactics to interrupt the chain of infection. Treatment is taking place in dedicated wards.

To restore the body’s electrolyte balance, patients with moderate to severe diarrhea need treatment with an oral rehydration mixture — essentially a medical-grade sports drink containing sodium and glucose dissolved in clean water. Treatment is simple and many patients need no hospitalization if treated promptly.

In severe cases, antibiotics are used to kill V. cholerae, although the main benefit is often a faster return to health and a reduction in the load of bacteria released in the feces.

Photo: PAHO

A patient in Saint Nicolas Hospital, St. Marc, Haiti, during the cholera outbreak. That hole in the bed accommodates the violent diarrhea that is cholera’s trademark.

Very versatile vermin

The cholera bacterium, like any self-respecting microbe, has evolved genetic tricks for optimizing its survival in changing circumstances. Once it passes through the human mouth, V. cholerae:

Photo: Dartmouth Electron Microscope Facility

The cholera culprit Vibrio cholerae infects its host quickly and spreads easily via diarrhea.

Cholera’s big gifts

Like an execution in the morning, fast-spreading cholera has served to concentrate the medical mind. Cholera was first seen for sure in 1817 in India; the disease then traveled with people and their commerce around the world and eventually gave humanity two durable gifts.

The first gift came when a mid-19th-century outbreak of cholera in London spawned the science of epidemiology — the study of epidemics. The story is often told of how, in 1854, physician John Snow marked where cholera cases lived, and realized that they all had gotten water from the same pump.

Even though the germ theory of disease was yet nascent, authorities removed the handle from the pump and the epidemic subsided. Although that removal is credited with ending the epidemic, it may have already been waning.

Images: Map; Snow: UCLA Department of Epidemiology

This map, drawn by Dr. John Snow (1813-1858), correlated London cholera cases (each marked by a dash) with drinking water from the Broad St. pump. Mouseover image for a photo of Snow, the founder of epidemiology.

Photo: Madison Metropolitan Sewerage District

Sewage treatment is essential for dozens of reasons, but many countries cannot afford expensive treatment systems.

Snow’s achievement is especially awesome considering that the bacteria that causes cholera would not be identified until 1883, by the great German microbiologist Robert Koch.
By correlating a disease with foul water, Snow showed that epidemics could be understood by analyzing the timing and location of the illnesses — two rudiments of epidemiology. And that led to a second gift: As epidemiologists realized that drinking feces was dangerous, not just disgusting, the health-giving revolution of sanitation got under way.

Virtuous vaccines?

Antibiotics kill cholera bacteria. But carpet-bombing with antibiotics (“mass chemoprophylaxis” in medico-lingo) is inadvisable because it stimulates bacteria to resist the drugs.

Vaccines must be given before an epidemic gets under way, and thus are most suitable in regions where cholera is endemic, like South Asia. But oral cholera vaccines are showing progress:

Breaking the chain

Infections are contained by interrupting the chain of infection; and no fundamental scientific or social hurdles prevent this from being done with cholera. Unlike HIV, cholera is not spread by sexual contact. Unlike tuberculosis or influenza, it is not spread by coughing.
Instead, cholera prevention requires attention to boring, even repulsive, topics like safe drinking water and sewage treatment. Granted, the technology can be expensive, but water and sanitation are also the primary defense against microbes, viruses and parasites that cause dozens of other waterborne diseases.

The United Nations’s Millennium Development Goals aim to raise the proportion of people getting clean water and adequate sanitation, but Unicef says progress is mixed: “Two and half billion people are still without access to improved sanitation – including 1.2 billion who have no facilities at all and are forced to engage in the hazardous and demeaning practice of open defecation. The news is better for water: the number of people without an improved source has dropped below one billion for the first time in history.”

Map: Unicef

Improved sanitation parallels national wealth. In Latin America and the Caribbean, 117 million people live without adequate sanitation.

In 2010, 884 million people have no access to “improved” drinking water, including 330 million in Sub-Saharan Africa, 222 million in Southern Asia and 151 million in Eastern Asia.
India and China account for the lion’s share of progress in both water and sanitation. Globally, city folks usually score higher in these basic barometers of human development.
So do rich people.

In terms of public health, clean water, clean air and sanitation are the big three environmental goals. By themselves, diarrhea diseases cause 4 percent of all time lost to illness, when measured by disability-adjusted life years.
The cholera question is scientifically straightforward, and is quickly solved when resources and social organization are available. Yet even if the victims of cholera are poor and powerless, the benefits of clean water and sanitation are so manifold that it’s hard to accept that these basic requisites for health are not for everybody.

But as the population soars, as people continue flooding into shantytowns around megacities, and as income inequality remains a fact of life, we anticipate this is not the last article you’ll read about such an avoidable epidemic.

Restaurant menu, illustrated fruit on top, menu items like bad bananas foster, rotten apple pie.

Going to choose between cheesecake and lean beef? Between beefcake and chicken Caesar salad?

NBC’s storyboards may suggest that you eat lean, and you may want to become the biggest loser, but your food choices could be less the result of a conscious decision than a response to some tongue-twisting chemicals floating through your cerebral backwaters.

In fact, there are signs that this decision could result from the same mechanism that operates in fruit flies — but we’re flying ahead of ourselves.

A study of fruit flies published today in Current Biology explores a “dietary switch,” a chemical mechanism that forces the fly to eat what it needs. After a female mates, for example, the switch guides her toward the protein-rich fungus on a rotten peach.

The same thing happens, through much the same mechanism, in flies that are deprived of protein.

But when flies are deprived of sugar, they gravitate toward sugary food, says study author Pankaj Kapahi, a geneticist at the Buck Institute for Age Research.

Fruit flies are an ideal organism for studying biology: their genetics have been heavily explored, and genes are widely shared among organisms. “The genes that regulate many processes are conserved,” Kapahi says. “Over 400 human disease genes have been found in fruit flies, so it is very pertinent to use a model like this, where we can get the answer at a fraction of the cost, and get it quickly.”

Rather fight than switch?

“The dietary switch is pretty amazing,” says Kapahi. “During life history and development, all organisms, from simple insects up to humans, need to switch the type of nutrients they consume.” Growing animals need more protein than older ones, and the several dietary switches help ensure they get what they need.

Kapahi admits that the existence of such innate mechanisms has been controversial, and they may seem more old wives’ tale than hard-core science, but he insists they are legit. “When you do not get much protein, or much carbohydrate, there are homeostatic mechanisms that tell the organism, ‘We need to find protein,’ or ‘We are running low on carbohydrate.’”

It stands to reason that evolution would craft such switches, but reason and reality do not always agree. And yet in lab experiments with the fruit fly, Kapahi found evidence that such switches are working, and even tracked down some of their chemical mechanisms.

The activity seems to center on the TOR (target of rapamycin — don’t ask us…) pathway, which helps detect the level of nutrients in the animal, and is also involved in diabetes and cancer. To explore how proteins work in the TOR pathway, Kapahi and colleagues found that certain proteins that triggered the TOR pathway caused un-mated females to eat more yeast.

Although those proteins caused the virgin ladies to eat like mated females, they did not change the choices of mated females, suggesting that their dietary switch had already been activated.

Here's the perfect Atkins diet meal! But fruitflies that eat the Atkins die young, says study author Pankaj Kapahi.

The aging connection

TOR is known to be “a nutrition sensor that’s found from plants to humans,” Kapahi says. “It’s the link between nutrients in the environment and growth. When you eat protein, the TOR signal is part of an ancient natural sensor that says ‘There is now enough food around, let’s turn these nutrients into protein and grow bigger.’”

But the current study “suggests that TOR is also an important pathway for balancing the nutrients, specifically protein and carbohydrate,” Kapahi says. Kapahi observes that TOR has also been linked to aging in four species. “If you inhibit TOR, you get a lifespan extension,” and the mechanism may help explain the anti-aging effects of caloric restriction.

Eventually, monkeying with the TOR signal system could be the basis for drugs against diabetes, obesity, cancer or aging itself. But because TOR does multiple jobs, “that could potentially have effects on how the animal selects its diet,” Kapahi says.

Already, finding that ancient genetic pathways can affect food choice in the fruit fly reinforces the notion that cellular processes are working to decide what we eat. “We humans unconsciously go toward certain foods,” says Kapahi. “Why do we combine rice and beans in so many cultures?”

Neither rice nor beans has all the amino acids needed for a complete protein, but together “they make a very nice mix,” Kapahi says. “We have been practicing this for thousands of years, without realizing why, but it gives us an optimal amino acid balance.”

The decision also took into account viruses found in Australia, South Africa and the tip of South America. “These countries were at the very beginning of the influenza season, when we wee at the tail end,” says Jonathan Temte, an associate professor of family medicine at UW-Madison.

Temte, who is a member of the CDC’s Advisory Committee on Immunization Practices, says jet planes are a virus’s best friend. A person, and any virus they carry, “can reach Wisconsin from anywhere in the world in less than one incubation period [one to three days].”

There is no guarantee that the vaccine will contain the exact strain of flu that is causing fevers, coughs, sore throats, aches and pains next winter, but an imperfect vaccine can still help, Temte says. “In general, if you were immunized with a mismatched vaccine, you would be still be less likely to contract the flu than if you were not immunized.”

Because the benefits of flu vaccine so greatly outweigh the minimal risks, experts say about 83 percent of the population, including virtually all people under age 18 or over age 50, should get vaccinated.

Now is the time to stand up and get your vaccine, Temte says.