Role of water fleas (Daphnia magna) in the accumulation of avian influenza viruses from the surrounding water.

Objective: To determine the role of water fleas in accumulating avian influenza viruses (AIV) from the surrounding water and to estimate their role as a vector of AIV.

Methods: Water fleas were exposed to H4N6 and H5N1 AIV-contaminated water in a closed system. The potential of water fleas to take up and retain the viruses was estimated by quantitative real-time RT-PCR (qRRT-PCR) and titration on cell culture.

Results: Contamination trials showed that significantly higher amounts of viral RNA were detectable per gram of water fleas as compared to per milliliter of the surrounding water at 1, 4, and 6 days of incubation. Viral infectivity was only detectable in the water samples collected immediately after mixing the virus in water containing the water fleas, while no virus was detectable in any of the water fleas or water samples collected afterwards.

Conclusions: Water fleas are able to accumulate AIV from surrounding water based upon the qRRT-PCR detection of viral RNA. Additional studies are necessary to investigate the inactivation potential of water fleas on viral infectivity.