Hepatitis C virus couldn’t be transmitted through shared drug preparation paraphernalia, but sharing paraphernalia was associated with sharing syringes nevertheless, according to researchers at Yale University, New Haven, Conn.

That makes sharing paraphernalia a “surrogate” for HCV transmission “resulting from sharing drugs,” the investigators said, but it should not be a primary focus of harm-reduction and education programs.

In their experiment, Robert Heimer, PhD , and his colleagues prepared syringes contaminated with HCV and attempted to replicate the conditions in which persons injecting drugs share packages of drugs, syringes, and paraphernalia.

“Water was introduced into the barrel of a contaminated ‘input’ syringe and expelled into a ‘cooker,’ and the water was drawn up into a ‘receptive’ syringe through a cotton filter,” the study authors explained. “The ‘input’ syringe, ‘cooker,’ and filter were rinsed with tissue culture medium and introduced into the microculture assay. The water drawn into the second syringe was combined with an equal volume of double-strength medium and introduced into the microculture assay” (J Infect Dis. 2017. doi: 10.1093/infdis/jix427 ).

The researchers tested syringes (with fixed or detachable needles), cookers, and filters (single or pooled). They were significantly more likely to recover HCV from detachable-needle syringes than from fixed-needle syringes. In the input syringes, they recovered no HCV from 70 fixed-needle syringes while they did recover HCV from 96 of 130 (73.8%) detachable-needle syringes. HCV passed to both types of syringes in the experiment’s receptive syringes but at a much higher rate for those with detachable needles than for those with fixed needles (93.8% vs. 45.7%, respectively).

No HCV was recovered from any of the cookers, regardless of syringe type. Some was recovered from filters, at higher rates with detachable needles than with fixed (27.1% vs. 1.4%).

“Money spent on ‘cookers’ and filters would be better spent on giving away more syringes,” Dr. Heimer and his coauthors concluded. “Because HCV and HIV transmission are more likely if the syringe has a detachable rather than a fixed needle, efforts should focus on providing more syringes with fixed needles.”