Something I often discuss when doing infection control talks is needlestick injuries. The contrast between the approach to needlestick injuries (and blood exposure in general) in veterinary and human medicine is pretty astounding. In humans, there are strong educational campaigns, careful reporting, testing and treatment protocols, and increasing use of "safety engineered sharps devices" like retractable or guarded needles. In veterinary medicine, getting stuck with a needle is often considered "part of the job" and "no big deal". A study we did of veterinary technicians a few years ago found that 74% of techs had suffered a needlestick injury in the past year (Weese & Faires, Canadian Veterinary Journal 2009). I’ve had many such injuries during my career, pretty much all before I started to focus on infection control, and I honestly didn’t put much though into them (beyond ”oh crap, that hurt!”).
There are some valid reasons for the differences between human and veterinary medicine when it comes to needlestick injury prevention, not the least of which is the risk of HIV and hepatitis B virus transmission. In some ways, getting people to pay attention to needlesticks in veterinary medicine is tough because we don’t have viruses such as these in our patients. Needlesticks can cause pain, significant trauma and rarely severe (including fatal) problems (e.g. from drug reactions or infections), but the vast majority are rather inconsequential. However, a line that I frequently use is: “We don’t have an analogue of HIV or hepatitis B… at the moment. New diseases continue to emerge and you never want to be the index case.”
Is this really a risk? Well, yes. Beyond some new disease that could emerge and be a serious problem, we also have new issues being identified from bugs that we’ve known about for a while. Recent concern has been expressed about transmission of Bartonella species. This is a strange group of bacteria that are commonly found in cats and dogs. Bartonella henselae is the cause of cat scratch disease, a well-known problem, but Bartonella are attracting a lot more attention these days because they are being implicated in a range of often vague human diseases. Bartonella can be found in the blood of healthy cats (and to a lesser degree dogs), raising questions about whether a needlestick could result in transmission of these bacteria to people.
Two case reports highlight these concerns.
The first one (Lin et al, Vector Borne and Zoonotic Diseases 2011) tells the story of a veterinarian who developed a fever of unknown origin and back pain. Ultimately, he was diagnosed with Bartonella henselae infection which they speculated may have been transmitted following a needlestick injury. The needlestick link is weak here though. As a veterinarian, there are lots of other opportunities to be exposed to Bartonella henselae. It’s not uncommonly present in the blood of healthy cats and the main route of exposure is through fleas. Fleas feed on the cat, pick up the bacterium, then shed it in their feces. Cat scratches are a common route of transmission as the contaminated flea feces may be driven into the body. The veterinarian in the report didn’t recall having been bitten or scratched recently, but recall bias is an issue since scratches are common and often forgotten if not severe. Flea exposure wasn’t queried. Also, the needle with which he was stuck was a clean needle that had not been used yet. It still could have been the source of infection if it acted like a scratch, driving infected flea dirt on his skin into the wound, but I don’t think this report is very strong.
The second article (Oliveira et al, Journal of Veterinary Internal Medicine 2010) describes infection by a different Bartonella speces, B. vinsonii berkhoffii, also in a veterinarian. The person was taking an aspirate from a mass with a needle and syringe and was poked in the finger as the dog was struggling. Five days after the needlestick, the person was still healthy. A blood sample was taken from the person and Bartonella was not found. However, by day 34 after the incident, the veterinarian reported having had frequent headaches for the past week, fatigue and some intermittent numbness in one arm. Bartonella vinsonii berkhoffii was detected in the person’s blood at that time. There was also an increase in anti-Bartonella antibodies between the two blood samples, which supports an active infection. The bacterium was not found in the tumour aspirate, but as a dog-associated bacterium and one that is rarely identified in people, and with the timing of exposure and disease, it’s quite suggestive that the needlestick was the source.
These may just be two reports, but they may just be the tip of the iceberg, because disease caused by Bartonella infections is often vague and probably routinely gets missed. There’s also increasing evidence of wide-ranging types of infection that may be overlooked, so people (and particularly veterinary staff) need to be aware and pay attention to the potential risk.
Needlestick injuries shouldn’t be considered part of the job. There are risks, but a little common sense goes a long way.
Information sheets on both cat scratch disease and needlestick injuries (and how to avoid them) are available on the Worms & Germs Resources – Pets page.