The committee first identified about 100 naturally occurring pathogens that could potentially have infected US troops during their service in the Gulf War, OEF, or OIF. The identified pathogens comprise viruses, bacteria, helminths, and protozoa that have been reported in southwest and south-central Asia, have historically caused outbreaks of illness in military populations, or have generated particular concern among US veterans of the Persian Gulf War. As required by PL 105-277 and PL 105-368, the pathogens include Escherichia coli, Shigella spp., Leishmania spp., and the Phlebovirus pathogens that cause sand fly fever.
Definition of Long-Term Adverse Health Outcome
The committee then developed a set of criteria for determining which infectious diseases to evaluate for strength of association with specific long-term adverse health outcomes. Long-term adverse health outcomes include secondary diseases or conditions (sequelae) caused by primary diseases, reactivation or recrudescence of diseases, and delayed presentation of diseases. A long-term adverse health outcome, the committee agreed, should have one or more of the following characteristics:
Significant interruption of normal physical and mental function outside the timeframe of acute infection.
Persistent organ dysfunction or damage.
Reproductive effects in military personnel, including birth defects in their offspring.
In addition, a long-term adverse health outcome could be reversible, related to secondary transmission,5 or both.
Development of Inclusion Criteria
Given that definition, the committee identified about 90 infectious diseases that have long-term adverse health outcomes and that were any of the following:
Endemic in southwest or south-central Asia during the period in question.
Diagnosed in US troops during the three deployments under study.
Of special concern to Gulf War, OIF, or OEF veterans.
Historically reported among military populations.
Many of the diseases have never been reported in US military personnel in close temporal relationship to deployment to southwest or south-central Asia for the Gulf War, OEF, or OIF. Even so, the committee could not rule out the possibility that one or more people contracted an unreported disease during deployment. Consequently, the committee created a tabular summary of such diseases’ acute and long-term characteristics.
In this context, secondary transmission means the spread of a pathogen directly from a primary human host to one or more other humans.