When Germs Get Tougher

Tracking infectious diseases has become more complex and more crucial than ever before. It used to be enough for individual health units in Canada simply to count the number of reported cases of tuberculosis or norovirus or E. coli in their area. That was sufficient when people worked, socialized and vacationed close to home. But today, with worldwide travel, changing immigration patterns and the frightening rise of drug-resistant strains of disease, this tracking system falls short.

Dr. Frances Jamieson, a professor in the department of laboratory medicine and pathobiology, has designed and created a new Internet-based surveillance and alert system called the Ontario Universal Typing of Tuberculosis Surveillance Program, or OUT-TB Web. So far, it’s just for tuberculosis, but it has the potential for expansion to other infectious diseases, other provinces and other countries.

Jamieson started with tuberculosis because the lab at Public Health Ontario, where she’s a medical microbiologist, was already identifying TB strains by their molecular “fingerprint” when requested by public-health units. “But the information was getting more complex,” says Jamieson. Most strains of TB are treatable by a six- to nine-month course of four antimicrobials, with a cure rate of 97 per cent. But the multi-drug-resistant strains, which are on the increase, require a very different regimen, lasting up to two years and with a cure rate of 70 per cent. There’s also a new, extensively drug-resistant strain, which requires yet a different course of treatment.

“We wanted to be able to provide the capacity to visualize and track cases and clusters in real time, as the cases were identified in the laboratory,” Jamieson explains. With OUT-TB Web, a sample from every newly diagnosed TB patient is sent to the lab for genotyping. When layered with confidential data and maps on where patients live, work and travel, patterns clearly emerge. Public-health units with access to the secure site can then see each case, including information about drug resistance, which helps determine treatment strategy.

OUT-TB Web can also help determine what constitutes an outbreak and what doesn’t. For instance, until now, four cases of TB in a single apartment building would likely instigate a large, costly investigation to confirm or refute if an outbreak is occurring. But OUT-TB Web could find the answer much more quickly. If the four strains match, it could be an outbreak, requiring changing the ventilation system, installing air filters or adding UV lighting (which kills tuberculosis) to dramatically reduce the transmission of this airborne pathogen. If the four strains are all different, it suggests it’s not an outbreak. This allows for better control of the disease and a smarter use of public-health resources.

With about 1,600 new cases a year in Canada, tuberculosis isn’t the concern it is in Asia and Africa, with more than eight million cases; at least, not yet. “TB is not a problem – until it is,” says Dr. Michael Gardam, a professor of medicine and director of infection, prevention and control at the University Health Network in Toronto. “All it takes is one case, and then it can get away from you.” TB is second only to HIV-AIDS as the largest killer worldwide due to a single infectious agent, killing one person every 20 seconds. “Most diseases are still tracked purely by adding up the number of cases by region, and one of our biggest challenges is that provinces don’t share data well. With this OUT-TB concept, we’re getting much more detailed information, which helps determine our intervention strategies.”

Jamieson, who has led the laboratory response in Ontario to many recent outbreaks, including SARS and the Walkerton water tragedy, says that other provinces and the United States have already shown interest in OUT-TB Web. Jamieson hopes to expand it to include E. coli and norovirus cases, layering on restaurants and agricultural and socioeconomic data, as well as sexually transmitted infections such as syphilis, whose rates in Toronto alone have skyrocketed 18-fold over the past decade.