In the past two nights, doctors in London have seen 207 cases of a disease that they cannot identify, 143 of them diagnosed just yesterday. Patients have been experiencing vomiting and profuse diarrhea. There also seems to be a rise in a milder “stomach flu” of some form that they aren’t sure is related to the more serious cases. No fevers have been reported in these patients. The doctors have been supporting their patients with rehydration, but that seems to be all they can do for now. Many of the patients are slipping into shock from the loss of fluids before a doctor can be called. This particular neighborhood has a street festival over the weekend and doctors are trying to draw a link between people who ate at certain stalls and people who are sick. So far, nothing obvious has appeared. They have, however, noticed that in a house with one sick person, they often find at least one more severely or mildly ill patient.
A number of the sick patients are young children who all attend a nearby school. Parents are starting to believe that the school is to blame and the building has been shut down until the outbreak subsides.

Day one: afternoon

You have received blood and urine samples from one of the case patients. Additionally, this patient’s stool has been cultured and the plate has been sent over for you.

Day two: morning

Now that doctors have been alerted to an outbreak, another 116 cases were reported last night. Rumors are spreading that there was a terrorist attack on the street festival or the school (the rumors vary) and residents are fleeing quickly, increasing fears that this disease may disperse throughout the world if it is not identified and controlled soon. One doctor has reported seeing stools from several patients containing bits of mucus that look like grains of rice in water.

Day two: afternoon

Another 54 cases have been discovered. It has been noted that the cases remain clustered in a single neighborhood and parents are still suspicious of the school, despite the fact that it has been closed for a week and people are still getting sick. The attached map of the neighborhood shows the locations of the school (on Broad street), the street festival (intersection of Berwick and Broad), a public water fountain (intersection of Broad and Poland), and a nearby animal slaughterhouse (square at Marshall and Silver) that residents have complained is a health hazard for years.
The current cases include: 2 cases at a home on the corner of Broad and Dufours Ct., 3 in the house next door, five next to that, a total of 17 on the block across the street, 15 dispersed throughout Dufours Ct., 23 at houses on Broad street immediately adjacent to the school, 20 on Bentinck, 9 on Poland north of Portland, 5 on Great Marlborough St., 15 on Silver Street near the slaughterhouse, 18 along Berwick St. between Broad and Portland and at least 18 cases along Peter Street west of Berwick. The other cases are dispersed mostly in the neighborhoods between Silver and Brewer streets. People attending the festival and children attending the school are drawn mostly from the area bordered by Regent St., Oxford St., Dean St. and Coventry St. (in gray on your map).
Blood tests on patients have been inconclusive and doctors are hesitant to continue to try and get blood samples from already badly dehydrated patients if they are not going to yield any information. Doctors are especially concerned because patients have started dying from this disease and appear to be suffering from a collapse of their circulatory system in some cases. Some doctors are reporting that as many as half of their patients have died.

Day three: morning

The good news is that the epidemic appears to be falling off somewhat. Only 46 new cases have been reported, possibly because the affected area of the city is largely empty as people have been fleeing in panic. Disturbingly, two of the newest cases occurred far outside the initial area of infection. Although analysis of food and other samples from the initial patients’ homes have yielded nothing unusual, an analysis of water from a public water fountain in the center of the neighborhood over the past several days has shown variable levels of bacteria normally associated with fecal contamination. On day one, they were normal and so the water was not considered as a source of the outbreak. However, over the past two days, these levels have risen dramatically and then fallen back down. It is unclear if this is related to the outbreak.
Interviews with family members have indicated that many of the case patients had not only been at the festival, but had been in the center of the neighborhood earlier in the day on the day they got sick (in the vicinity of the public water fountain).
People have panicked and refuse to return to their homes until this epidemic is identified and controlled. Meanwhile, it is clear that case patients have fled the initial infection area and may be spreading it to other areas.
Doctors are reporting that so far all that has worked is supporting their patients with intravenous fluids to keep them from going into shock. The patients that can survive seem to be clearing the disease within about 5 days. One doctor has insisted on treating all of his patients with antibiotics, but other doctors in the same hospital report that his patients do not seem to be recovering any faster or more often than the patients that have only been on IV fluids.