Although we do not know whether individual host properties or random events associated with the OPV infection (e.g., the replication site) determine the ability to excrete long-term, we assume a pre-determined patient-specific ability to excrete long-term, if surviving long enough and infected after clinical PID onset.
Released into the air during birthing or miscarriages by infected goats, a single bacterium is enough to infect a human, causing symptoms much like flu, though more persistent.
Although the titers of viremia in JEV-infected humans, horses and cattle seem not to be high enough for infecting mosquitoes [ 2, 4, 5], JEV can cause febrile illness and encephalitis, mainly in humans and horses [ 1- 3, 6], and occasionally in cattle [ 7- 9].
For instance, respiratory viruses severe enough to keep victims in bed are likely to be displaced by less-severe strains whose victims are mobile enough to infect others.
To produce a spore small enough to infect the lungs took great skill.
It is not clear that those levels would be enough to infect anyone, and federal officials have asserted that the muscle meat is safe.
The strain of SARS that Dr. Li brought to Linhe was powerful enough to infect six immediate family members, at least nine medical workers and a county propaganda official who rode on a train with Dr. Li.
That appraisal was based on tests showing that the number of tuberculosis bacteria in the man's sputum were too low to be detected but still enough to infect others.
Dr. Matthew Meselson, a Harvard University biologist who has studied biological warfare, said some monkey experiments suggested that a single spore would be enough to infect and kill particularly vulnerable animals.
House sparrows -- ubiquitous, dust-colored, one-ounce crumb-snatchers -- are probably a principal reservoir here; new tests at federal laboratories show they can harbor the virus for five days or more at levels high enough to infect mosquitoes that bite them.
