Post-exposure prophylaxis

Post-exposure prophylaxis
eMedicine 1991375

Post-exposure prophylaxis, also known as post-exposure prevention (PEP), is any preventive medical treatment started after exposure to a pathogen (such as a disease-causing virus), in order to prevent the infection from occurring.

Rabies

PEP is commonly and very effectively used to prevent the outbreak of rabies after a bite by a rabid animal. The treatment consists of a series of injections of rabies vaccine and immunoglobulin.[1] Rabies vaccine is given to both humans and animals who have been potentially exposed to rabies.[2]

Tetanus

Tetanus toxoid can be given in case of a suspected exposure to tetanus. In such cases, it can be given with or without tetanus immunoglobulin (also called tetanus antibodies or tetanus antitoxin[3]). It can be given as intravenous therapy or by intramuscular injection.

The guidelines for such events in the United States for non-pregnant people 11 years and older are as follows:[4]

Vaccination status Clean, minor wounds All other wounds
Unknown or less than 3 doses of tetanus toxoid containing vaccine Tdap and recommend catch-up vaccination Tdap and recommend catch-up vaccination
Tetanus immunoglobulin
3 or more doses of tetanus toxoid containing vaccine AND less than 5 years since last dose No indication No indication
3 or more doses of tetanus toxoid containing vaccine AND 5–10 years since last dose No indication Tdap preferred (if not yet received) or Td
3 or more doses of tetanus toxoid containing vaccine AND more than 10 years since last dose Tdap preferred (if not yet received) or Td Tdap preferred (if not yet received) or Td

HIV

History

AZT was approved as a treatment for AIDS in 1987. As AIDS patients started seeking treatment in medical centers, it sometimes happened that a healthcare worker would be exposed to HIV during work. Some people thought to try giving health care workers AZT to prevent seroconversion. This practice dramatically decreased the incidence of seroconversion among health workers when done under certain conditions.[5]

Later the question arose of whether to give HIV treatment to people who had non-occupational exposure, for example, when a condom breaks while a person with HIV has unprotected sex with an HIV-negative person in a single incidence, or in the case of unprotected sex with an anonymous partner, or in the case of a non-habitual incident of sharing a syringe for injection drug use. Evidence suggests that PEP also reduces the risk of HIV infection in these cases.[6]

Since taking HIV-attacking medications shortly after exposure was proven to reduce the risk of contracting HIV, this led to research into pre-exposure prophylaxis by taking medication before a potential exposure to HIV occurred.

Risk evaluation

Risk factor are considered in HIV post-exposure prophylaxis. For example, having unprotected sex with HIV positive partner is considered risky, but sharing sex toys, spitting and biting considered to be negligible risk for evaluation of pep. The highest non-sexual risk is blood transfusion and the highest sexual contact risk is receptive anal intercourse.[7]

Treatment

In the case of HIV exposure, post-exposure prophylaxis is a course of antiretroviral drugs which reduces the risk of seroconversion after events with high risk of exposure to HIV (e.g., unprotected anal or vaginal sex, needlestick injuries, or sharing needles).[8] The CDC recommends PEP for any HIV negative person who has recently been exposed to HIV for any reason.[8]

To be most effective, treatment should begin within an hour of exposure.[9] After 72 hours post-exposure PEP is much less effective, and may not be effective at all.[8] Prophylactic treatment for HIV typically lasts four weeks.[8][10]

While there is compelling data to suggest that PEP after HIV exposure is effective, there have been cases where it has failed. Failure has often been attributed to the delay in receiving treatment (greater than 72 hours post-exposure), the level of exposure, duration of treatment (lack of adherence to the 28-day regimen), or all three. However, given that—for non-occupational exposures—the time and level of exposure are based on patient-supplied information, absolute data is unavailable. The standard antibody window period begins after the last day of PEP treatment. People who received PEP are typically advised to get an antibody test at 6 months post-exposure as well as the standard 3 month test.[8]

The antiretroviral regimen used in PEP is the same as the standard highly active antiretroviral therapy used to treat AIDS. It requires close compliance and can have unpleasant side effects including malaise, fatigue, diarrhea, headache, nausea and vomiting.[8]

A report from early 2013 revealed that a female baby born with the HIV virus displayed no sign of the virus two years after high doses of three antiretroviral drugs were administered within 30 hours of her birth. The findings of the case were presented at the 2013 Conference on Retroviruses and Opportunistic Infections in Atlanta, U.S. and the baby is from Mississippi, U.S. The baby—known as the "Mississippi baby"—was considered to be the first child to be "functionally cured" of HIV.[11] However, HIV re-emerged in the child as of July 2014.[12]

Hepatitis A

For exposure to hepatitis A, human normal immunoglobulin (HNIG) and/or hepatitis A vaccine may be used as PEP depending on the clinical situation.

Hepatitis B

If the person exposed is an HBsAg positive source (a known responder to HBV vaccine) then if exposed to hepatitis B a booster dose should be given. If they are in the process of being vaccinated or are a non-responder they need to have hepatitis B immune globulin (HBIG) and the vaccine. For known non-responders HBIG and the vaccine should be given whilst those in the process of being vaccinated should have an accelerated course of HBV vaccine.

Hepatitis C

Persons exposed to hepatitis C should get monthly PCR, and if seroconversion occurs then interferon, with possible ribavirin.

See also

References

  1. ↑ "Rabies: Guide for post-exposure prophylaxis". World Health Organization. Retrieved 2013-05-28.
  2. ↑ Wiktor TJ, Macfarlan RI, Reagan KJ, Dietzschold B, Curtis PJ, Wunner WH, Kieny MP, Lathe R, Lecocq JP, Mackett M (1984). "Protection from rabies by a vaccinia virus recombinant containing the rabies virus glycoprotein gene". Proc. Natl. Acad. Sci. U.S.A. 81 (22): 7194–8. PMC 392104 Freely accessible. PMID 6095272. doi:10.1073/pnas.81.22.7194.
  3. ↑ tetanus in Encyclopædia Britannica. Last Updated 7-17-2013
  4. ↑ , from Centers for Disease Control and Prevention. Page last updated August 12, 2013.
  5. ↑ Cardo, D. M.; Culver, D. H.; Ciesielski, C. A.; Srivastava, P. U.; Marcus, R.; Abiteboul, D.; Heptonstall, J.; Ippolito, G.; Lot, F.; McKibben, P. S.; Bell, D. M. (1997). "A Case–Control Study of HIV Seroconversion in Health Care Workers after Percutaneous Exposure". New England Journal of Medicine. 337 (21): 1485–1490. PMID 9366579. doi:10.1056/NEJM199711203372101.
  6. ↑ Katz, M. H.; Gerberding, J. L. (1997). "Postexposure Treatment of People Exposed to the Human Immunodeficiency Virus through Sexual Contact or Injection-Drug Use". New England Journal of Medicine. 336 (15): 1097–1100. PMID 9091810. doi:10.1056/NEJM199704103361512.
  7. ↑ "Updated Guidelines for Antiretroviral Postexposure Prophylaxis After Sexual, Injection Drug Use, or Other Nonoccupational Exposure to HIV— United States, 2016" (PDF). Centers for Disease Control and Prevention, U.S. Department of Health and Human Services. Retrieved June 24, 2016.
  8. 1 2 3 4 5 6 Smith, Dawn K.; Grohskopf, Lisa A.; Black, Roberta J.; Auerbach, Judith D.; Veronese, Fulvia; Struble, Kimberly A. (21 January 2005). "Antiretroviral Postexposure Prophylaxis After Sexual, Injection-Drug Use, or Other Nonoccupational Exposure to HIV in the United States". cdc.gov. Centers for Disease Control. Retrieved 7 July 2011.
  9. ↑ Diprose, P; Deakin, C.D.; Smedley, J (2000). "Ignorance of post-exposure prophylaxis guidelines following HIV needlestick injury may increase the risk of seroconversion". British Journal of Anaesthesia. 84 (6): 767–770. PMID 10895754. doi:10.1093/oxfordjournals.bja.a013591. Retrieved 7 July 2009.
  10. ↑ "HIV/AIDS Bureau - HIV Care Pocket Guide 2006 - Occupational HIV Postexposure Prophylaxis (PEP)". Retrieved 2008-03-05.
  11. ↑ Saundra Young (4 March 2013). "Researchers: Toddler cured of HIV". CNN. Retrieved 4 July 2013.
  12. ↑ National Institute of Allergy and Infectious Diseases (10 July 2014). ""Mississippi Baby" Now Has Detectable HIV, Researchers Find". NIH. Retrieved 12 August 2014.

Further reading

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