Studies on Influenza Virus Transmission between Ferrets: the Public Health Risks Revisited

Fouchier, Ron A. M.

Research on influenza virus transmission via respiratory droplets or aerosols between ferrets is performed in facilities and under conditions that are specifically designed for the purpose of such studies (12) (13) (14) (15) (16) . In ordinary BSL3 laboratories, including diagnostic laboratories, work is performed in open-front class 2 biosafety cabinets with directional airflow, aimed at protecting the environment from release of pathogens and protecting laboratory workers from exposure. Contrary to ordinary BSL3 conditions for work with viruses, all in vivo and in vitro experimental work on influenza virus transmission in the Erasmus MC facility is carried out in class 3 isolators or class 3 biosafety cabinets, which are airtight boxes with negative pressure (ϽϪ200 Pa), to ensure inward flow in case of leakage (12, 16) . Handling is done through airtight gloves fitted to the front of these cabinets. Air released from the class 3 units is filtered by high efficiency particulate air (HEPA) filters and then leaves directly via the facility ventilation system, again via HEPA filters. Only authorized and experienced personnel that have received extensive training can access the facility. For animal handling, personnel always work in pairs to reduce the chance of human error. Although the laboratory is considered "clean" because all experiments are conducted in closed class 3 cabinets and isolators, special personal protective equipment, including laboratory suits, gloves, and FFP3 (class 3 filtering face piece) facemasks, are used, and all personnel are vaccinated with the homologous A/H5N1 vaccine. All equipment in the fa-cilities is monitored electronically, and alarm systems are employed to ensure that workers do not enter the facilities if equipment is malfunctioning. All personnel have been instructed and trained how to act in case of incidents, which are handled upon consultation between a senior staff member, a clinical microbiologist, the institutional biosafety officers, and the facility management. Antiviral drugs (oseltamivir or zanamivir) are used immediately in the event that an incident should occur. Every incident in the laboratory is followed up by actions to prevent such incidents from happening again. The facilities, personnel, and procedures are inspected by the U.S. CDC every 3 years, in agreement with the U.S. select agent regulations for overseas laboratories and by the Dutch government (Inspectie Leefomgeving en Transport [ILT] inspection) (12, 16) .