Lab Matters Winter 2018 - Page 13

from the bench Alaska communities, 160 miles apart and both experiencing parvovirus outbreaks. The hope was the lab’s NGS technology could reveal whether they were due to gaps in canine immunization, a novel strain or possibly both. The Alaska State Virology Lab is one of a growing number of public health labs with NGS technology. In a year, all state labs are expected to have acquired NGS technology, many with support from the US Centers for Disease Control and Prevention’s (CDC’s) Advanced Molecular Detection (AMD) initiative. Part of the early wave of adopters, the Alaska State Virology Lab first brought its NGS technology on site in 2014. The lab is still in the process of validating its use as an official diagnostic tool , rather than only a reference tool. The parvovirus experiment helped move that validation process forward, Chen said, adding to a growing evidence base that NGS technology can be effectively used in outbreak investigation. Canine Parvovirus Parker noted that the NGS results did seem to match the parvovirus strains used to make the canine vaccine, which means better immunization coverage may have prevented or slowed the outbreaks. To conduct the parvovirus study, results from which were published last August in Scientific Reports, Parker, Chen and colleagues tested 12 rectal-swab specimens from dogs involved in the larger outbreaks and with clinical signs consistent with parvovirus. Using NGS, they were able to detect and characterize replicating canine parvovirus in the samples—that’s significant, Parker said, because it means the virus was mostly likely the cause of the dogs’ symptoms. NGS also revealed two distinct subtypes of parvovirus that were geographically distant. The NGS results, coupled with more traditional serological testing for virus antibodies, suggested that the outbreak wasn’t due to a novel strain of parvovirus, but likely to exposures within an under- or unvaccinated dog population. Parker noted that the NGS results did seem to match the parvovirus strains used to make the canine vaccine, which means better immunization coverage may have prevented or slowed the outbreaks. “It was surprising because we had thought it was one giant outbreak,” Parker said. “But instead, one community had one virus and the other had a different one—they were two distinct events.” PublicHealthLabs @APHL Beyond demonstrating the capacity for NGS in outbreak investigation, the study also helped demonstrate its use in post-mortem testing, said Chen, who also serves as an associate professor in the Department of Biology and Wildlife at the University of Alaska- Fairbanks. It’s difficult to find assays validated for cadaver blood, Parker said, but NGS was able to reveal reliable information using rectal swab samples from deceased canines. Overall, Parker, Chen and study co-authors Molly Murphy and Karsten Hueffer concluded that the “NGS methodology proved to be an effective diagnostic tool.” While both the Fairbanks lab and the state public health lab in Anchorage are still validating their NGS methodology, they’re the only labs in the state with the capacity to use NGS in infectious disease outbreak investigation. That’s important, Parker said, because it will allow lab workers to turnaround critical epidemiological information much quicker than before. For example, Chen said the lab hopes to use NGS to better understand transmission networks related to hepatitis C infection, case counts of which have tripled nationally in the past few years among young adults with a history of injection drug use. If the Fairbanks lab can use NGS to reveal a clearer geographic picture of transmission risks, fellow public health workers could more precisely target hepatitis C prevention strategies, such as disease screening and education. In fact, the Fairbanks lab is already immersed in such work as one of four state labs participating in the CDC/APHL project GHOST—Global Health Outbreak and Surveillance Technology—which is focused on hepatitis C transmission. Back to the parvovirus outbreak, Parker said the NGS results didn’t come out until after the state’s big mushing races, so researchers weren’t able to alleviate any fears of a novel strain before the dog-sledding races took off. Still, the findings do underscore the importance of keeping Alaska’s dogs fully immunized. “Dog mushing is our state sport,” Parker said. “Bad publicity can be really hurtful to our communities and to our state, so it’s important to everyone to get a handle on it.” n Winter 2018 LAB MATTERS 11