Risk Assessment for Arthropod Vectors

THE INTENT OF this section is to provide guidance and to establish a framework for selecting the appropriate arthropod containment level (facilities, equipment, and practices) that reduce risks of release and exposure of laboratory workers and the public to a vector and associated agents. “Risk” implies the probability that harm, injury, or disease will occur among laboratorians or the general public because of accidental release of a competent disease vector and/or associated agents. In the context of vector research laboratories, risk assessment considers two kinds of effects: direct effects, such as biting, infestations, and myiasis, and indirect morbidity and mortality due to the pathogens transmitted. The latter is by far of higher concern, and direct effects will not be considered here. Therefore, in this document, arthropod containment levels are directly correlated with the appropriate BSL levels of the agents with which they are naturally or experimentally infected or may transmit in the event of accidental release (see U.S. Dept. of Health and Human Services, 1999, Section VI). While the focus of this document is public health risk, effects on animals because of arthropods known to transmit animal disease are to be considered. Researchers are encouraged to consult with the U.S. Fish and Wildlife Service and USDA-APHIS regarding risks and regulation before completing a risk assessment. The laboratory director or principal investigator has primary responsibility for assessing risks in order to set the appropriate biosafety level for the work. This is done in close collaboration with the Institutional Biosafety Committee (IBC) to ensure compliance with established guidelines and regulations. Development and review of the risk assessment and the planned safety precautions by consultation with experts in the biology and public health significance of the arthropod is essential. In performing a qualitative risk assessment, all the risk factors are first identified and explored considering related information available such as BMBL, the NIH Recombinant DNA Guidelines, the Canadian Laboratory Biosafety Guidelines, the WHO Biosafety Guidelines, and the ACAV Catalogue of Arboviruses. In many cases, one must rely on other sources of information such as field data, the literature concerning aspects of vector competence, and environmental requirements through consultation with recognized experts in arthropod and pathogen relationships. The greatest challenge of risk assessment lies in those cases where complete information on these factors is unavailable. A conservative approach is advisable when insufficient information forces subjective judgment.