records, and confirmation by the investigators suggested that those with records had used them when completing the questionnaire. Only 2.8% of veterans without records reported receiving pertussis vaccination despite the fact that the anthrax and pertussis vaccines were always administered simultaneously. Of those with records, 36% reported receiving pertussis vaccination. Reporting of biologic-warfare vaccinations (for example, anthrax, plague, and pertussis) was associated with “CDC syndrome” (that is, Centers for Disease Control and Prevention multisymptom syndrome), irrespective of the use of records. However, an association of routine vaccinations (for example, hepatitis, typhoid, and cholera) with CDC syndrome was present only in those who did not use their records. The analysis, therefore, provides some evidence of bias with regard to self-reporting of vaccinations.

The investigators limited a later analysis focused on the same cohort to the subset of personnel who had vaccination records (Hotopf et al. 2000). That analysis concluded that multiple vaccinations received during deployment (but not multiple vaccinations received before deployment) were associated with symptom clusters.

Kelsall et al. (2004a) specifically asked Australian Gulf War veterans to refer to their own immunization booklets for information regarding the number and timing of immunizations relative to their Gulf War deployment. Although data were not provided in the paper, the authors report that the 52% of the 1,418 survey respondents who had immunization booklets reported higher total numbers of immunizations than those without booklets and were less likely to report not having received any immunizations. That suggests a general pattern of underreporting of exposures among veterans who provided self-reported vaccination information. The paper does not provide specific information on the types of immunizations reported, nor does it evaluate any potential bias regarding the source of vaccination records and the reporting of health outcomes.

Exposure to Pyridostigmine Bromide

Pyridostigmine bromide (PB) is a drug that was used during the Gulf War as a pretreatment to prevent the harmful effects of nerve agents because of its ability to reversibly bind to acetylcholinesterase (AChE).1 The bound fraction is thereby protected from exposure to nerve agents that would irreversibly bind to AChE. PB is not an antidote (it has no value when administered after nerve-agent exposure) and is not a substitute for atropine or 2-pralidoxime chloride; rather, it enhances their efficacy (Madsen 1998).

DOD reported that 5,328,710 doses were fielded and estimated that about 250,000 personnel took at least some PB during the Gulf War.2 It was supplied in a 21-tablet blister pack; the dosage prescribed was one 30-mg tablet every 8 hours. Each pack provided a 1-week supply of PB for one person, and military personnel were issued two blister packs each. Recommended long-term storage was at 2-80°C, and blister packs removed from refrigeration were to be used


AChE is an enzyme necessary to remove acetylcholine (ACh). ACh transmits nerve signals at the cholinergic neuromuscular junction or synapses in the central nervous system. Anticholinesterase agents inhibit (inactivate) AChE, and this results in an accumulation of ACh. The accumulation repetitively activates the ACh receptors, resulting in exaggerated responses of organ (such as excess salivation).


The number of doses fielded was learned through a search of archived Defense Personnel Support Center logistic records for Operations Desert Shield and Desert Storm and reflects the amount of product ordered and sent through supply channels. In most cases, only a review of people’s own medical-treatment records would report the actual number of doses administered, and few records were maintained by them (Office of the Secretary of Defense 1998).

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