UN officials on the peacekeeping mission feared that outbreaks of violence would occur during the trial.
Dr. Lubroth showed that outbreaks appeared in areas with the largest concentrations of domestic chickens, pigs and people.
The animals have always been present on the reef but it is possible that outbreaks are now more severe and more frequent.
Both he and Dr. Lubroth, speaking at a Rockefeller University conference on animal-human diseases, showed that outbreaks had not followed flyways or migration schedules.
"We've been lucky so far but we have to be prepared" for the possibility that outbreaks will occur in this country.
It also means that outbreaks that once might have faded away unnoticed now set off alarms, for better and for worse.
Consumer groups said that outbreaks had persisted under the current system, and noted that a significant share of imports were brought to the United States by smaller companies.
This suggests that outbreaks such as the one in Haiti in 2010 11, where cholera had long been absent, are not rare.
That does not mean that outbreaks of hemorrhagic fever are inevitable, said Kevin J. Olival, leader of the bat-hunting team at EcoHealth Alliance.
Dr. Mack argues that outbreaks can be stopped quickly by vaccinating exposed people, and that unless the risk of an attack is high, there is no real need to expose workers to the vaccine's risks.
According to the C.D.C., noroviruses are associated with cruise ships partly because cruise ships are monitored by health authorities, so that outbreaks on board are more likely to be identified and reported.
