Needlesticks

Needlesticks

Rob Orman MD and Greg Moran MD

 

Take Home Points

• The highest risk exposure with known HIV positive blood and a large hollow needle has a 1 in 300 seroconversion rate.

• A housekeeper stuck by a needle in the trash with an unknown source is highly unlikely to seroconvert.

• HIV does not last long in dried blood or on needles.

• Human bites are unlikely to transmit HIV.

 

• We frequently have to care for employees with body fluid exposure. Much of the encounter involves talking with the patients and reassuring them.  Bloodborne pathogen transmission in the workplace is exceedingly rare. Even with the highest risk exposures, the risk of transmission is still very low. Is there an algorithmic approach to make this easier?

• There are three main infectious pathogens we worry about with body fluid exposure; hepatitis B, C and HIV. The focus for exposures to hepatitis B is on the vaccination status of the exposed person. Have they had post-vaccination antibody titers?

• For HIV, you need to consider how much blood the patient was exposed to and how much HIV do you think was in the blood? These are often unknowns. You don’t always know the HIV status of the source and if they have a high or low viral load. Sometimes it is a judgement call as to how much blood was involved. Was it a hollow or solid needle stick? Was there a lot of blood present? Mucous membrane exposures are generally lower risk. We ask the patient to participate in the determination of risk. Some are willing to accept a risk of 1 in a million and others will want to take the antiretroviral medications and risk the associated toxicity.

• A frequent presenting scenario is a housekeeper stuck by a needle in the trash with an unknown source.

• Patients are primarily worried about contracting HIV. The probability that the needle is contaminated by HIV is relatively low.  There are 1.2 million infected with HIV out of more than 300 million people. Most patients in the hospital do not have HIV.

• HIV does not survive long in dried blood or on needles. It probably lasts hours at most.  If the needle has dried blood, the risk of transmission is very low.

• Even the highest risk exposure with a hollow needle and fresh blood with a known HIV positive source has conversion rate of 1 in 300.

• The risk of transmission from a needle stick in the trash would range from one in tens of thousands to millions. It would be unusual circumstances that would prompt recommendations for post-exposure prophylaxis in this setting. It would have to be a fresh needle with a high probability of HIV and a deep stick from a hollow bore needle. This constellation of findings would be unlikely.

• A healthcare provider experiences a needle stick from a hospitalized patient. A rapid HIV test is drawn on the source patient and is negative. Is this enough to tell them not to worry? Yes. You are done. In the rare circumstance that the patient has acute retroviral infection but no antibodies, many facilities are using testing that detects the p24 antigen and are able to detect these acute HIV infections before the antibody becomes positive.

• We frequently see cops who are bitten. What should you do? These are low risk exposures. There have been some very rare case reports of HIV transmission allegedly carried through a human bite. Saliva doesn’t really contain large amounts of HIV relative to other body fluids. If there is a blood to blood component of exposure through the bite, you might consider prophylaxis. However, it would be very rare to recommend post-exposure prophylaxis for this type of exposure.

• What is the time interval from exposure to post exposure prophylaxis? The sooner the better. There is no specific cutoff. You want to get the antiretrovirals on board before the virus can enter the cells and start to replicate. This can happen over hours. The data is poor. Workplace transmission is so rare that we are unlikely to ever have robust data. We have some evidence that post-exposure prophylaxis reduces risk based on case control studies for high risk exposures.

• If you aren’t sure, it is reasonable to give the first dose. This toxicity of the antiretroviral medication happens over time. The toxicity of a single dose is relatively low. Many emergency departments have these readily available. In most cases the source patient is HIV negative. However, if it will be difficult to obtain rapid HIV testing due to an uncooperative patient, there is no available blood, etc and it is a high risk exposure, it is reasonable to treat.

• What is the time cutoff for when post-exposure prophylaxis does not have benefit? 72 hours is commonly cited. At this point, the strategy is to follow them for seroconversion. Even for a high risk exposure, the risk is only 1 in 300.

• Can you test the needle? No.

• It is a high risk needle exposure with a known HIV positive source, large hollow-bore needle with a deep stick and you want to give medications. What do you give and when do they need follow-up?

• Get your infectious disease doctor involved.

• In general, you treat for four weeks.

• Baseline labs to assess liver function and CBC are obtained.

• Patients will usually have follow-up for antibody testing for HIV in 8-12 weeks and then at 6 months. Some will follow-up even later but six months is usually considered the usual window for seroconversion.

• Patients should usually have follow-up within a week to make sure they are tolerating the medications.

• Does follow-up testing differ if the source patient is unknown status versus known HIV positive? Not really. However, if the patient’s status is known, testing can evaluate for drug resistance patterns.

• What if the source patient refuses a blood draw or can’t consent? The laws vary between states. However, most states allow some avenue for testing in these circumstances. In most states you no longer need written consent to test available blood. If the patient is refusing a blood draw, some states require a court order to draw blood against their will. In the meantime, you are going to have to make a decision to treat based on perceived risk.

• What do you advise people with a high risk exposure regarding intercourse with their partner? The risk is exceedingly low but not zero. It may be prudent to use barrier precautions in the interim.

• Hierarchy of risk of transmission; fresh blood>dried blood>semen>urine>saliva>vomit. Once you get past fresh blood, the risk of transmission goes down. The risk of transmission for a single instance of vaginal intercourse between an HIV positive male and HIV negative female is estimated at 1 in 1000. This may increase in certain circumstances such as sexual assault with associated trauma.

• What is the risk of transmission? Hollow-bore needlestick has a risk around 1 in 300. Mucous membrane exposure is 1 in 1000. Non-intact skin exposure has a risk of greater than 1 in 1000.

• Should we give post-exposure prophylaxis to victims of sexual assault? If there is reason to believe the assailant is more likely to be infected with HIV and there is some blood exposure, then yes.

• More resources include MDcalc or the UCSF clinicians post-exposure prophylaxis line at 1-888-448-4911