Post-exposure prophylaxis
Post-exposure prophylaxis (PEP) is the time-limited use of antimicrobials, immune globulin, or vaccine after a defined exposure to prevent an infection from establishing. For HIV, the standard regimen is tenofovir disoproxil fumarate/emtricitabine plus raltegravir or dolutegravir, started within 72 hours and continued for 4 weeks; rabies, hepatitis B, tetanus, meningococcus, pertussis, and varicella each have their own pathogen-specific regimen.
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What this article covers
- Overview
Post-exposure prophylaxis (PEP) is a time-limited antimicrobial, immune globulin, or vaccine course given after a specific exposure, to prevent infection before it establishes, covering human…
- Epidemiology
HIV exposure: a percutaneous needlestick occupationally, or condomless sex, sexual assault, or shared injection equipment nonoccupationally; transmission risk from a single needlestick is about 0.3%…
- Risk factors
Exposure route: percutaneous or mucous-membrane/nonintact-skin contact with blood carries the highest bloodborne risk; non-bloody saliva, tears, or urine is negligible risk.
- Pathophysiology
HIV: exposure infects local dendritic cells and CD4 T cells, then spreads systemically over days; a three-drug regimen blocks reverse transcription and integrase-mediated proviral DNA integration.
- Clinical features
Occupational or bloodborne exposure: a percutaneous or mucosal exposure to blood or body fluid, evaluated within minutes to hours; if source hepatitis B surface antigen status is unknown or positive…
- Differential diagnosis
Pre-exposure prophylaxis: ongoing daily antiretroviral therapy started before any exposure, unlike PEP, which requires a discrete exposure within the preceding 72 hours.
- Diagnosis
Exposure classification establishes the need for treatment, not a test result in the exposed person: PEP is offered when there is percutaneous injury or mucosal/nonintact-skin contact with blood from…
- Management
First, irrigate any wound with soap and water or saline.
- Complications
Antiretroviral adverse effects: nausea, diarrhea, fatigue, and headache are the leading cause of early discontinuation; monitor renal function with tenofovir disoproxil fumarate.
- Prognosis
HIV PEP: historically studied with zidovudine monotherapy, associated with an approximately 80% reduction in seroconversion risk; modern regimens perform at least as well, and efficacy falls sharply after 72 hours.
- Prevention
HIV pre-exposure prophylaxis: daily tenofovir disoproxil fumarate or alafenamide plus emtricitabine, or a long-acting injectable, for ongoing high risk; check HIV, hepatitis B, kidney function, and…
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Acute HIV infection, also called the acute retroviral syndrome, is the symptomatic viremic phase in the days to weeks after HIV acquisition, presenting with fever, fatigue, myalgia, rash, and pharyngitis at a time when antibody testing may still be negative. Diagnosis requires an HIV RNA viral load, and antiretroviral therapy should begin as soon as the patient is ready, regardless of CD4 count.
- Rabies
Rabies is a bullet-shaped rhabdovirus transmitted by bat, raccoon, skunk, or dog bites that causes a uniformly fatal encephalomyelitis once symptoms begin, marked by hydrophobia and aerophobia. Prevention is everything: thorough wound washing plus rabies immune globulin and vaccine given before symptom onset prevents disease, but there is no effective treatment after clinical rabies develops.
- Hepatitis B virus (HBV) infection
Hepatitis B virus is a bloodborne and sexually transmitted DNA virus that causes acute hepatitis and, when infection becomes chronic, progresses through immune-tolerant, immune-active, immune-control, and reactivation phases toward cirrhosis and hepatocellular carcinoma. Diagnosis rests on hepatitis B serology, chronic infection is treated with entecavir or tenofovir, and reactivation during immunosuppression is prevented with prophylactic antiviral therapy.
- Tetanus
Tetanus is a clinically diagnosed neurologic syndrome caused by Clostridium tetani toxin (tetanospasmin), which blocks inhibitory neurotransmitter release and produces trismus, risus sardonicus, opisthotonos, and autonomic instability. Treatment is hospitalization with tetanus immune globulin, wound debridement, benzodiazepines for spasm control, and airway support, since consciousness remains intact throughout.
- Meningococcal meningitis
Meningococcal meningitis is an acute bacterial infection of the meninges caused by Neisseria meningitidis, an encapsulated gram-negative diplococcus that spreads by respiratory droplets and classically causes a petechial rash. It is an infectious disease emergency treated with empiric ceftriaxone and vancomycin plus dexamethasone, followed by penicillin or ceftriaxone once confirmed, with chemoprophylaxis for close contacts.
- Bordetella pertussis (whooping cough)
Whooping cough is a highly infectious bronchitis caused by the gram-negative coccobacillus Bordetella pertussis, marked by catarrhal, paroxysmal, and convalescent stages with lymphocytosis; diagnosis is clinical, confirmed by nasopharyngeal PCR, and treated with azithromycin plus prophylaxis of close contacts.