Table 1. Reported incidents of poliovirus release from laboratories and vaccine production facilities in the pre–polio vaccine era*.
| Year | Location (reference) | Source | Poliovirus type | No. cases* | Exposure |
Description | ||
|---|---|---|---|---|---|---|---|---|
| Primary | Secondary | Tertiary | ||||||
| 1933 |
United States (20,21) |
Lab |
Not indicated |
1 |
Physician |
NA |
NA |
Bitten (cutaneous disruption) by a normal macaque while doing work on poliomyelitis (paralysis); filterable virus capable of reproducing the disease in rabbits was isolated from the case; case was fatal |
| 1935 |
United States (22) |
Vaccine production facility |
Not indicated |
12 |
Vaccine trial patients, age 5 mo to 20 y |
NA |
NA |
12 cases of paralytic poliomyelitis in patients receiving trial vaccination against poliomyelitis; natural infections ruled out as cause; 6 deaths |
| 1941 |
United States (19,20,23) |
Lab |
Not indicated |
1 |
Lab staff |
NA |
NA |
Lab staff member experienced paralysis after preparation of infected tissues for inoculation into monkeys; cutaneous inoculation; no polio outbreaks reported in place of residence or areas of travel |
| 1945 |
United States (20,23) |
Lab |
Not indicated |
1 |
Lab staff |
NA |
NA |
Lab staff member scratched on hand by noninoculated monkey during transport; subsequent virus contamination of hands might have occurred while feeding or inoculating monkeys; patient experienced paralysis and later died |
| 1946 |
Zimbabwe (formerly Rhodesia) (20,25) |
Lab |
Not indicated |
1 |
Lab staff |
NA |
NA |
Infection acquired during inoculation of monkeys with polio virus; paralysis occurred, case was fatal |
| 1949 |
United States (20,24) |
Lab |
WPV2 (mouse- adapted Lansing strain) |
2 |
Lab staff |
NA |
NA |
Two lab technicians were infected in the eyes and nose with Lansing (Armstrong) strain while inoculating mice during polio experiments; both experienced paralysis |
| 1950 |
Canada (20,25) |
Lab |
Not indicated |
1 |
Physician |
Na |
NA |
Doctor acquired poliomyelitis while performing autopsy on poliomyelitis patient; intracutaneous inoculation; residual weakness; case was not fatal |
| 1954 | United Kingdom (20,26) | Lab | WPV2 (MEF-1) strain | 1 | Lab staff | NA | NA | Lab technicians infected by cutaneous inoculation while performing necropsy on animals infected with wild type-2 (MEF-1) strain; subsequent paralysis; cases were not fatal |
*Cases defined as laboratory positive (with or without paralysis) for poliovirus by standard methods of virus isolation or known exposure to poliovirus. Lab, laboratory; MEF-1, wild poliovirus type 2 laboratory reference strain; NA, not applicable; WPV2, wild poliovirus type 2.