(AP) -- Blood specialist Dr. Cay-Uwe von Seydewitz has been making his rounds 16 to 18 hours a day, seven days a week, since the outbreak of a deadly bacterial epidemic.
The wing he's in charge of was a construction site a month ago - hastily converted back into useable space to keep up with the spike in patients needing massive blood plasma exchanges to try and purge their systems of the toxins from the aggressive, previously unknown form of E. coli.
Like other doctors, nurses and hospital staff around Germany, for von Seydewitz taking a day off has not been an option.
"If you have a new illness, it's important to have the same doctor from the start to the end to see how it changes over time," said von Seydewitz, wearing blue hospital scrubs and sporting a 5 o'clock shadow at midday, standing near stacks of supplies in brown boxes still on their pallets.
Investigators on Friday breathed a sigh of relief, saying that their epidemiological probe of the pattern of the outbreak produced enough evidence to conclude vegetable sprouts from a farm in Lower Saxony were the cause of the outbreak - even while noting that work for medical professionals was far from over. As of Saturday, the outbreak had killed 33 people and sickened nearly 3,100.
"There will be new cases," warned Reinhard Burger, head of the Robert Koch Institute - Germany's national disease control center.
In Kiel and Luebeck, which have also been hit hard in the outbreak, doctors have been taking only short naps on stretchers in hospital hallways and staying in the building for days in a row, said Oliver Grieve, the spokesman for the university hospitals in the northern cities.
Others canceled their vacations or called in from hospitals around the country to offer their help for overwhelmed clinics in northern Germany.
"There has been a very high level of commitment," Grieve said. "It is amazing to see how everyone has done the utmost to help out in this crisis."
More than 700 of the patients in Germany are suffering not only from diarrhea and cramps but have also developed a life-threatening complication that can cause kidney failure, and require round-the-clock medical care.
Dr. Friedrich Hagenmueller, the medical director of Asklepios Hospital Altona, the hospital where von Seydewitz works which has seen about 200 patients total, noted that with such an illness it's not just the doctors and nurses working overtime but the cleaning staff.
"We brought people back from the holidays - they must constantly clean and disinfect the toilets," he told The Associated Press during a break in making his rounds. "The turnover of the patients is relatively quick, and when a patient is released they have to quickly clean and disinfect the toilets and I haven't heard a word of complaint."
While the numbers of newly infected patients are slowly declining, hospitals are still working to the limit with hundreds of people still in intensive care. Earlier this week, health authorities said there were still some 670 patients suffering from severe complications including kidney failure, paralysis and epileptic seizures.
"We still have some extra 12 dialysis nurses from southern Germany working with us" at the university hospitals in Kiel and Luebeck, Grieve said.
At Asklepios Hospital in Hamburg this week, von Seydewitz was overseeing 22 patients undergoing blood plasma exchange to try and remove the toxins from their system. In the procedure, doctors remove which four liters (quarts) of blood plasma and replace it with fresh plasma for three days in a row - or longer if needed.
At the start of the outbreak von Seydewitz said he only had two machines to perform the relatively rare procedure, but since then has leased more machines, and borrow others from the hospital's dialysis treatment area and now has a total of eight functioning.
"Now we also have patients from other hospitals for the procedure as well," he said.
With the high demand for blood plasma, Germany's Red Cross has begun special blood drives.
In normal times, hospitals need between 500 and 700 250 milliliters (8.5 fluid ounce) portions of blood plasma in 14 days, they used 12,000 portions in the last two weeks, said Jense Lichte from the Red Cross.
People responded, with donations up 14.5 percent since the outbreak began, he said.
"Luckily, Germans have been coming to our blood drives," Lichte said, saying that despite the high demand the country never ran close to a real shortage.
In addition to physical exhaustion, some doctors say the epidemic has also taken a high emotional toll.
"It has been very stressful for all of us because we are dealing predominantly with younger patients without significant previous diseases ... many of us were deeply moved when a lot of these cases developed in such a dramatic way," said Marc Voss, a senior internist at Regio Clinic Elmshorn northwest of Hamburg. "The identification with the patients is very high, because one thinks 'it could have been me.'"
Some 77 percent of patients in Germany are women and the majority of them are between 20 and 50 years old, most fit and with healthy lifestyles.
"Our staffers are used to seeing very severe cases," said Grieve. "But to see those young, healthy girls break down from one day to the next, getting cramps and slipping into coma - that's been the most stressful thing ever."
Grieve added that even the psychologists at the hospitals were working day and night to comfort the traumatized family members of the sick who have been waiting for weeks in some cases for signs of recovery.
Karolin Seinsche, 29, has been in the hospital for the last two weeks slowly recovering from seriously complications from the sickness.
In that time she said she has received 11 blood exchanges on von Seydewitz's floor, and needed near constant care when she was first admitted to the intensive care ward with bloody diarrhea and cramping.
"There were a lot of ups and downs," she said, lying in her bed near the window, propping her head up with a pillow. "Just when I'd think it was getting better it would then get worse again - but now it's stable."
A vegetarian, Seinsche said she did not see herself doing an about-face on her eating habits, but that the sickness was so frightening and recovery so long that she was going to double wash everything before she ate it in future - even bananas.
"I've never done that before - who does - but now I will," she said.
Explore further: CDC: Raw tuna suspected as Salmonella source in outbreak