Rabies Management and Symptoms

Rabies Management

• The management of rabies exposure is categorized into category II and III, where the biting animal cannot be observed within 14 days.
  • The risk of rabies transmission is determined based on the animal's behavior, whether the animal can be observed for rabies symptoms, and the type of exposure.
• Rabies Symptoms and Progression:
  • Rabies progresses with symptoms of hydrophobia (involuntary, painful contraction of the muscles in the pharynx, larynx, and diaphragm) and aerophobia (fear of air/open space).
  • These symptoms indicate brainstem involvement, leading to exaggerated reflexes protecting the respiratory tract and hypersalivation (“foaming at the mouth”).
  • If not managed, brainstem dysfunction rapidly progresses to coma and death within a week, often from respiratory or cardiac arrest.
  • A form of rabies, paralytic rabies, presents with flaccid muscle weakness starting from the bitten extremity and progressing to quadriparesis and facial weakness.
  • Urinary incontinence is common in these cases
• Ancillary Tests:
  • Ancillary test examination of cerebrospinal fluid (CSF) may show mild elevations in protein levels and mononuclear cell pleocytosis.
  • Magnetic resonance imaging (MRI) of the brain may reveal signal abnormalities in the brainstem or other gray-matter areas.

Rabies Exposure Categories and Management:

• Exposure Categories:
  • Category I: Feeding/touching an animal, licking of intact skin, exposure to the patient with signs, symptoms of rabies by contact with eating or drinking utensils, casual contact (talking to, visiting, feeding suspected rabies cases), nibbling of uncovered skin with or without bruising/hematoma, minor/superficial scratches/abrasions without bleeding.
  • Category II: All category II exposures on the head and neck, transdermal bites, avulsions, or scratches with spontaneous bleeding, licks on broken skin or mucous membranes, exposure to rabies patient through bites, contamination of mucous membranes or open skin lesions with body fluids.
  • Category III: Unprotected handling of infected carcasses, ingestion of raw infected meat, exposure to bats.
• Management:
  • Category I exposures typically require only immediate washing of the exposed skin with soap and water.
  • Category II exposures necessitate vaccination and, in some cases, administration of rabies immune globulin (RIG).
  • Category III exposures always mandate immediate vaccination and administration of RIG.

Rabies Vaccine Information:

• Available tissue culture vaccines:
  • Purified Vero cell rabies vaccine (PVRV) - 0.5 mL/vial and 1.0 mL/vial.
  • Purified chick embryo cell vaccine (PCECV) - 1.0 mL/vial.
• These vaccines typically provide an immune response within 7-10 days, potentially lasting for years.

Post-exposure Prophylaxis (PEP):

• High rate of immunogenicity at day 14 and day 30 (98% and 100%, respectively).
• PEP schedule: days 0, 3, 7, 14, and 28.
• Intramuscular administration is recommended for individuals with specific conditions such as chronic liver disease, conditions involving chloroquine or systemic steroids, or hematologic disorders.
• Individuals with HIV, cancer, those on immunosuppressive therapy, or who have undergone transplantation should receive both the vaccine and RIG for both category II and III exposures.

Rabies Immune Globulins (RIG):

• Passive immunization products that provide neutralizing antibodies at the site of exposure, especially for category III exposures.
• Two types:
  • Derived from human plasma (20 IU/kg body weight).
  • Purified equine antibodies (F(ab')2, 40 IU/kg body weight).

Wound Infiltration Instructions (RIG):

• Infiltrate the wound around and into the bite wound with the calculated dose of RIG, anatomically feasible, even if the wound has healed.
• Any remaining RIG does not require intramuscular injection.
• RIG should be administered simultaneously with rabies vaccine, only once, ideally on the day of the bite, or up to 7 days after the first vaccine dose if not possible on the day of the bite.
• Avoid RIG after 7 days.

This quiz covers the management practices for rabies exposure, focusing on category II and III cases. It details the symptoms and progression of rabies, including hydrophobia and aerophobia, and highlights the urgency of treatment to prevent severe outcomes. Test your knowledge on rabies and its clinical implications.