Limited or Suggestive Evidence of No Association

Evidence from well-conducted studies is consistent in not showing an association between exposure to a specific agent and a specific health outcome after exposure of any magnitude. A conclusion of no association is inevitably limited to the conditions, magnitudes of exposure, and length of observation in the available studies. The possibility of a very small increase in risk after exposure cannot be excluded.

For many potential long-term adverse health outcomes of the nine identified diseases, there is no evidence of an association. In this report, the committee focused on identifying positive associations between specific infectious diseases and specific long-term adverse health outcomes and did not present the numerous long-term adverse health outcomes for which there is no association.


Each branch of the US military has polices regarding tuberculin skin testing and treatment of latent TB infection (LTBI). The most effective way to mitigate TB transmission and activation is to identify and treat for LTBI. In addition, the only way to determine whether military personnel and reservists have become infected with M. tuberculosis during their service is to test all personnel for TB shortly before and after deployment. Such testing would make it possible to trace cases of active TB to periods of military service if that is when infection occurred.

Department of Defense (DOD) policy specifies that predeployment serum specimens for medical examinations will routinely be collected within 1 year of deployment and that postdeployment serum specimens for medical examinations will be collected no later than 30 days after arrival at the demobilization site, home station, or in-patient medical treatment facility. The committee agrees with DOD’s overall policy regarding collection and use of serum specimens. However, for banked serum specimens to be most useful for determining whether infectious exposures occurred during deployment, the predeployment specimens need to be collected before travel. Current policy allows for collection of predeployment serum specimens up to 1 year after deployment. If the collection of serum is not done until after deployment, it would be difficult to ascertain whether any signs of infection found in the “predeployment” specimen are due to exposure during the current deployment or before it.

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