NEW YORK (Reuters Health) - Contact tracing on its own may be an inaccurate means of determining the degree of transmission in tuberculosis outbreaks, Norwegian researchers report. Because simultaneous reactivation of infection can occur during the development of an outbreak, genotyping is required to establish sources of infection.
Reporting in the February issue of Thorax, Dr. Ulf R. Dahle, at the Norwegian Institute of Public Health in Oslo, and colleagues present findings of an outbreak that occurred in 2003 involving 15 recent immigrants in the same community. All 15 had social contact with each other and 13 belonged to the same church.
Fourteen cultures were positive for M. tuberculosis, but DNA restriction fragment length polymorphism analysis showed that six different genotypes were involved.
It turned out that five patients infected with unique isolates had not acquired the infection from the putative source. The investigators even found that two patients within the same family were infected with different strains.
“The assumed transmission link to the index case is especially important when presuming drug susceptibility patterns in culture negative cases,” Dr. Dahle’s group points out.
They emphasize that “traditional contact tracing needs confirmation by genotyping before transmission patterns of M. tuberculosis can be conducted ... especially between patients with several risk factors for infection.”
Source: Thorax 2005;60:136-137. [ Google search on this article ]
MeSH Headings:Communicable Disease Control: Environment and Public Health: Epidemiologic Methods: Health: Health Occupations: Medicine: Investigative Techniques: Population Characteristics: Preventive Medicine: Public Health: Specialties, Medical: Public Health Practice: Contact Tracing: Analytical, Diagnostic and Therapeutic Techniques and Equipment: Biological Sciences: Health CareCopyright © 2002 Reuters Limited. All rights reserved. Republication or redistribution of Reuters content, including by framing or similar means, is expressly prohibited without the prior written consent of Reuters. Reuters shall not be liable for any errors or delays in the content, or for any actions taken in reliance thereon. Reuters and the Reuters sphere logo are registered trademarks and trademarks of the Reuters group of companies around the world.
