Why Data Mining the Cell Phone Records In Germany is Important in Identifying the HUS Outbreak Source ?

This is a follow-up to Using the Cell Phone Data of Foreigners/Visitors to Find the German E.Coli Source

You will find below two documents from the European Center for Disease Prevention and Control and the Robert Koch Institute (RKI) that point to their level of understanding back on May 26/27th. The Health Ministry of Germany still seems to say that they don't know the source of the outbreak eight days later. The other news are hat the specialists are still asking people what they have eaten when in fact, the two reports below show you that you just need to be in physical contact (hand to hand) with people that have been exposed to it to get sick. In short, getting the cell phone records of sick people might be a much better way to evaluating second hand exposure than asking people if they have eaten raw tomatoes. If the exposure to a large part of the population is due to uncleaned surfaces touched by first exposed people then asking whether they have eaten tomatoes won't help. We now have 12 countries with citizens who have been exposed to this outbreak and so we are beginning to have enough statistics to find out the culprit. 

From a May 27th European Center for Disease Prevention and Control risk assessment:

"...The update provided by Germany on 27 May reports 276 cases of HUS since 25 April. While HUS cases are usually observed in children under 5 years of age, in this outbreak 87% are adults, with a clear predominance of women (68%). Cases in children of school age are also reported. Two people affected by HUS have died. The onset of disease relating to the latest reported case was 25 May. New cases are still being reported.
Laboratory results from samples taken from patients have identified STEC strain of serotype O104:H4 (Stx2-positive, eae-negative). A German study has shown that eae-negative STEC strains generally affect adults more than children. Two strains isolated from patients from Hesse and Bremerhaven were shown to be highly resistant against third  generation cephalosporins (ESBL) and resistant to trimethoprim/sulfonamid and tetracyclines. Most cases are from, or have a history of travel to, northern Germany (mainly Hamburg, Northern Lower Saxony, Schleswig-Holstein). Clusters of cases were reported from Hesse and linked to a catering company that supplies cafeterias. These most likely constitute a satellite outbreak.
The source of the outbreak has not yet been confirmed and intensive investigations are ongoing. German health authorities suspect that contaminated food is the vehicle of the outbreak, based on the epidemiological description (e.g. age and geographical distribution) of the cases. Current investigations are focused on raw vegetables. Preliminary results of a case-control study (with 25 cases and 96 controls) conducted by the Robert Koch Institute (RKI) and the health authorities in Hamburg demonstrate a significant association between disease and the consumption of raw tomatoes, fresh cucumbers and lettuce. Considering that the ongoing outbreak included many cases with a severe course of disease, the RKI and the Federal Institute for Risk Assessment (BfR) recommend people in Germany to abstain from consuming raw tomatoes, fresh cucumbers and leafy salads, especially in the northern part of the country, until further notice. Regular food hygiene rules remain in effect. .."

the Robert Koch Institute (RKI) 

"...
Preliminary results of the STEC/HUS Case Control StudyPreliminary results of the epidemiological case-control study conducted jointly by the Robert Koch Institute and Hamburg Health Authorities show that the patients affected by the current EHEC outbreak consumed raw tomatoes, cucumbers and lettuce significantly more often compared to the healthy controls. However, whether only one or more of these three vegetables are associated with the outbreak remains unclear.Although the consumption of the described food items could explain the majority of the HUS-cases, other food items cannot be definitely excluded as the source of infection. The study was carried out in Hamburg only; therefore results cannot be generalized to other affected areas in Germany.In total 25 cases with HUS and 96 controls from Hamburg were included in the study since Friday, 20th of May 2011. They were matched according to gender, age group and area of residence. Detailed information concerning consumed food, eating habits and other possible sources of infection was compared between the hospitalized patients and healthy individuals (controls).The outbreak has affected the Northern part of Germany most severely, suggesting that the contaminated food items were mainly distributed there. Nevertheless, as HUS-cases were reported from other parts of Germany as well, contaminated food items could be present in other regions as well.As the outbreak is still ongoing and the public health impact is serious, the RKI and the BfR recommend as a precaution until further notice - in addition to the usual hygienic measures concerning handling of fruits and vegetables – not to eat raw tomatoes, cucumbers and lettuce, especially in the Northern Germany.It remains of vital importance for all persons with diarrhea to follow strict hand hygiene, especially if in contact with small children and immunocompromised individuals. Recommendations for good kitchen hygiene practice, as described in the BfR information sheet (www.bfr.bund.de), remain valid.Date: 26.05.2011.."

Great Thoughts Friday: Using the Cell Phone Data of Foreigners/Visitors to Find the German E.Coli Source

Dirk sent as a comment to the suggestion to use cell phone data to uncover the source (or sources)

Well that approach seems interesting. However, a first issue is that Germany and especially the Germans are peculiar with data privacy and probably there will be an outcry in the media about such an approach. A second issue: How should one interpret the outcome of such an approach. Isn't is probable that the outcome will be something like: "These people visited public restroom frequently" or "have been at Pharmacies or Doctors". In short: How to distinguish cause and effect?

On the first issue: In a democracy, the use of data that has already been collected can always be used for other purposes as long as you have the right filtering tool in effect. I am sure Germany can find ways to set up a privacy commission that oversees the use of this data in times of crisis. Five hundred sick people and  some twenty dead  count as a crisis in my book. 

On the second issue, I recall how John Snow discovered the source of a Cholera source in London: By mapping the location of the sick/dead people by their habitation.

Even he had to do additional thinking after having collected the data (use a diffusion model) to find the epicenter of the disease ( a water handle on Broad street). The way I see I see it, the authorities have no clue. We still don't know if it's in the water system, transportation system, airborne, foodstuff, everything is on the table. Throwing this new layer of information might put additional constraint on the infinite number of solutions they already have (an underdetermined system of some sort).

Of specific interest are the outliers: the foreigners and the Germans not living in Hamburg. Some of them were there for a short time and so are likely the ones whose locations are most interesting. They are probably the ones putting the most constraints on this underdetermined system.

Mining the Cell Phone Data to Find the Source of the German Super E-Coli outbreak

A commenter to A solution to finding the E-Coli outbreak source in Germany stated that with 500 cases, mining the cell phone data was not a major undertaking. Let me make the case it is. As far as we understand, we still don't know the nature of the contamination, in effect everything is on the table: water, food, aerial pathogen and it looks like the incubation period is three to eight days. It is not a case of finding out if all these people went to one restaurant or something similar. the issue is figuring out if given all these records, there are other records linking them together. For instance, let us imagine it is a cucumber foodstuff (it looks like it is not), the data mining would figure out all the paths of the sick people and then figure out if all these locations are connected by other cell phone location data ( those of the people selling the sick people the foodstuff). In the end, it may take two or three iterations and additional constraints before having some sorts of the places of interest.  

A solution to finding the E-Coli outbreak source in Germany

The current E-coli outbreak in Germany seems to stun the specialists. Maybe they ought to use other specialists! Here is my proposition, since everybody has a cell phone, including the sick foreigners, get the people at telecom companies to cooperate with the health authorities and provide a travel map of each and everyone (Germans and foreigners) who has become sick (we are talking more than 500 people now) and start some major data mining.

From afar, the problem looks like an instance of randomized group testing.