CONCLUSIONS

The perpetrator of the Anthrax outbreak of 2001 has been identified by the FBI as Bruce Ivins. The conclusions presented here do not address the criminal investigation, but rather how public health officials dealt with the anthrax outbreak.

Public health epidemiologists typically wear three hats, depending on the outbreak phase that is unfolding. The first stage is the crisis manager or fire fighter, trying to contain the outbreak before large numbers are infected. The second stage, more often occurring at the same time, is acting as disease detective, finding out details of what occurred, who was involved, when cases began and ended, and how webs of causation intricately link microbes and humans. The third stage is health educator, guiding the public on modes of prevention both for those at immediate risk and persons who might encounter similar risks in the future.

FIRST STAGE (Fire Fighter)

The first stage of addressing the American Anthrax Outbreak of 2001 has gone well. A deadly outbreak was contained, limited to America's East Coast, with few cases (22 initially counted, but perhaps only 18) and even fewer deaths. Yet while minor in disease burden, the outbreak was large enough to show what a clever and determined terrorist or group of terrorists could do to harm the nation. Thus the outbreak served as a proof-in-concept, now established by a perverse mind or diabolic group.

Details of how epidemiologists address outbreaks have been described at this site, including writings of CDC, clinicians, the news media and others. Clever and thorough detective work has identified the infected cases, determined the mode of transmission, and clarified local conditions that facilitate transmission. Eighteen cases were acquired through direct contact with Anthrax spore-containing letters. Four were possibly infected through contact with letters that earlier had been contact with spore-containing envelopes. What has not yet occurred is finding the perpetrator, a task better handled by criminal detectives, notably the Federal Bureau of Investigation. While the Anthrax outbreak was fearful in content and mysterious in scope, the process of puzzle-solving is similar to other epidemiologic investigations.

The last stage is perhaps the most important since if done well, many lives will be saved.

To help educate the public, CDC epidemiologists during the Anthrax outbreak have regularly presented their findings via their website, held press conferences, and actively involved both the print and electronic media as vehicles of information and education. All of these educational vehicles are included at this site. As a result of such efforts, the public has come to understand the problem, physicians are aware of what to look for among patients, and political leaders understand the importance of leadership, thoughtful reflection, and decision-making to prevent future occurrences.

Cases. By the end of 2001, CDC had identified 22 cases as being part of the outbreak: 11 confirmed as cutaneous anthrax (4 suspected and 7 confirmed) and 11 as the more deadly inhalational anthrax. One person in the first week of December was excluded because he did fit the case definition, accounting for 22 rather than 23 cases, as appeared earlier in the outbreak. More cases are being searched for, with CDC identifying seven needing further evaluation. In March 2002, another case arose in a laboratory worker, contaminated while handling an anthrax specimen that came from the original mailings. This accidental laboratory case of cutaneous anthrax (addenda) is not considered by Professor Frerichs to be part of the outbreak.

Cross-contamination. Perhaps most intriguing in this final stage of the investigation are the potential cases of mail cross-contamination, being four (cases 4, 18, 22, 23). If anthrax-laden envelops could have been pushed or beat during the mail sorting and stamping process so that minute spores are transmitted to surrounding envelopes, then those going through the Trenton, New Jersey postal facility who come in contact with secondary envelopes around September 18 or October 9 might also be at risk. Or alternatively the risk could over a longer duration if the machines are contaminated, passing spores to mail that follows in the coming days or weeks.

How high is the risk? If the four mysterious cases are due to secondary transmission, then the numerator of the risk is 4. But what is the denominator? Possibly there were hundreds of thousands of envelops that came in contact with the seven or more envelops that held the spores. Could these envelopes be laying around households, still unread or untended?

The United States Postal Service has the means to trace envelops by bar-codes, but it is a time consuming and expensive undertaking, not to be done lightly. Thus before embarking on an expensive intervention, the Postal Service is awaiting confirmation on risk of cross-contamination from CDC. As of December 7, CDC has issued incriminating comments about cases 4 and 18, but still views cases 22 and 23 as mysteries. Thus no further action has yet being suggested for the Postal Service to undertake.

How will the situation be resolved? CDC on December 7, 2001 issued the following statement, taking into account the apparent low risk of cross-contamination: "Despite this very low risk (as documented), persons remaining concerned about their risk may want to take additional steps such as not opening suspicious mail; keeping mail away from your face when you open it and not blowing or sniffing mail or mail contents; washing your hands after you handle the mail; avoiding vigorous handling of mail, such as tearing or shredding mail before disposal; and discarding envelopes after opening mail. However, the effectiveness of these steps in reducing any residual risk is not known." They further recommend, "Suspicious persons or situations should be reported to law enforcement authorities. Health-care providers should remain alert for persons with clinical presentations consistent with early anthrax, obtain appropriate diagnostic tests (e.g., blood cultures and chest radiograph), and report suspicious illnesses to local or state public health authorities." Finally CDC concludes with a thought about deaths: "Fatalities can be minimized by promptly initiating combination antimicrobial therapy."

Click for Time magazine article on problems protecting the public's health (1/14/02)