Survival of Hepatitis C Virus in Syringes Is Dependent on the Design of the Syringe-Needle and Dead Space Volume

Many people who inject drugs (PWID) use syringes with detachable needles, which have high dead space (HDS). Contaminated HDS blood may substantially contribute to the transmission of HIV, hepatitis C (HCV), and other blood-borne viruses within this population. Newly designed low dead space (LDS) syringe-needle combinations seek to reduce blood-borne virus transmission among PWID. We evaluated the infectivity of HCV-contaminated residual volumes recovered from two LDS syringe-needle combinations.

We tested two different design approaches to reducing the dead space. One added a piston to the plunger; the other reduced the dead space within the needle. The two approaches cannot be combined. Recovery of genotype-2a reporter HCV from LDS syringe-needle combinations was compared to recovery from insulin syringes with fixed needles and standard HDS syringe-needle combinations. Recovery of HCV from syringes was determined immediately following their contamination with HCV-spiked plasma, after storage at 22°C for up to 1 week, or after rinsing with water.

Insulin syringes with fixed needles had the lowest proportion of HCV-positive syringes before and after storage. HCV recovery after immediate use ranged from 47%±4% HCV-positive 1 mL insulin syringes with 27-gauge ½ inch needles to 98%±1% HCV-positive HDS 2 mL syringes with 23-gauge 1¼ inch detachable needles. LDS combinations yielded recoveries ranging from 65%±5% to 93%±3%. Recovery was lower in combinations containing LDS needles than LDS syringes. After 3 days of storage, as much as 6-fold differences in virus recovery was observed, with HCV recovery being lower in combinations containing LDS needles. Most combinations with detachable needles required multiple rinses to reduce HCV infectivity to undetectable levels whereas a single rinse of insulin syringes was sufficient.

Our study, the first to assess the infectivity of HCV in residual volumes of LDS syringes and needles available to PWID, demonstrates that LDS syringe-needle combination still has the greater potential for HCV transmission than insulin syringes with fixed needles. Improved LDS designs may be able to further reduce HCV recovery, but based on the designed tested, LDS needles and syringes remain intermediate between fixed-needle syringes and HDS combinations in reducing exposure to HCV.

Below:  Comparison of Syringe Combinations Tested in This Study. (A) From left to right, the photo shows an insulin syringe with attached needle, a 1 ml tuberculin syringe with detachable needle, a 3 ml Luer-lock syringe with detachable needle, a 2.5 Noloss syringe with the piston withdrawn from the hub of the syringe. (B) Going clockwise from the upper left, the photo shows a 23 gauge, 1¼” standard needle, a 25 gauge, 5/8” standard needle, a 25 gauge, 5/8” lower dead space (LDS) needle, and a 23 gauge, 1¼” standard lower dead space (LDS) needle. Note the addition plastic inside the LDS needles that serve to reduce the dead space.

Full article at: http://goo.gl/XIIr6X

By: Binka M1, Paintsil E1,2,3, Patel A1, Lindenbach BD4, Heimer R1,3

• 1Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, Connecticut, United States of America.
• 2Departments of Pediatrics & Pharmacology, Yale School of Medicine, New Haven, Connecticut, United States of America.
• 3Center for Interdisciplinary Research on AIDS, Yale University, New Haven, Connecticut, United States of America.
• 4Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut, United States of America.  

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