I was thinking about this earlier after reading reports of bodies being stacked in the streets. According to Time, it’s actually a myth that corpses lead to outbreaks of disease. What’s not a myth: When a country that didn’t have much medical infrastructure to start with loses what little it has and people are forced to resettle in the close quarters of refugee cramps, you’re staring at epidemics of typhoid, cholera, or worse. Which makes me wonder, even with the death toll already possibly in six figures, how high it’s going to go.

That vulnerability will be felt first in the water. In a major disaster, time is of the essence, and survivors will succumb to thirst and dehydration much faster than malnutrition. With drinking water distribution systems destroyed — and survivors crammed into camps without much sanitation — water supplies could quickly become contaminated. That can lead to rapidly spreading water-borne diseases like cholera and dysentery, which can sweep through refugee camps. (In the 1994 Rwanda refugee crisis, cholera took some 45,000 lives in less than three weeks.) That, in turn, puts emergency responders in a race against time — shipping in clean water or purifying existing supplies before diseases start spreading. And it’s not just drinking water that will be in demand. Latrines need to be set up quickly to prevent contamination. “It’s called WatSan — water and sanitation,” says Patrick McCormick, a spokesperson for UNICEF. “That will be the key.”…

The next danger will be existing infectious diseases that might attack survivors — especially in the cramped and less than hygienic conditions of a refugee camp. Measles and other childhood infections will be particularly worrying, especially since nearly half of Haiti’s population is under the age of 18, and many are already in poor health. Doctors will need to launch vaccination drives to protect the vulnerable and do so fast. In past disasters, like the 2004 Asian tsunami, lack of vaccinations before the event had a major impact on the spread of diseases after it.

The country already has a high incidence of HIV and TB and of course diseases related to malnutrition and rancid food. A U.S. microbiologist expects the aftereffects to last for years and calls, explicitly, for a Marshall plan to help the country rebuild. That’s how total the devastation is, as the photos demonstrate only too well.

Here’s CNN’s interview with Haiti’s president from earlier today. He’s dazed, understandably, but puts out the call for doctors and medical supplies of all sorts in the second half of the clip. The Red Cross’s donation page is here; the Doctors Without Borders donation page is here.