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Questions and Answers
What is the structure of the rabies virus?
What is the structure of the rabies virus?
Which animal is primarily responsible for the transmission of rabies to humans?
Which animal is primarily responsible for the transmission of rabies to humans?
What is a crucial first step in rabies post-exposure prophylaxis?
What is a crucial first step in rabies post-exposure prophylaxis?
Which of the following is NOT considered a main reservoir for rabies virus?
Which of the following is NOT considered a main reservoir for rabies virus?
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What type of RNA genome does the rabies virus possess?
What type of RNA genome does the rabies virus possess?
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What percentage of people bitten by rabid animals are children under 15 years old?
What percentage of people bitten by rabid animals are children under 15 years old?
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Which of the following is an effective method to prevent rabies?
Which of the following is an effective method to prevent rabies?
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What is a significant characteristic of the rabies virus that aids in its attachment to host cells?
What is a significant characteristic of the rabies virus that aids in its attachment to host cells?
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What is the primary method of virus transmission for rabies?
What is the primary method of virus transmission for rabies?
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Which of the following factors does NOT influence the consequence of rabies exposure?
Which of the following factors does NOT influence the consequence of rabies exposure?
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Which phase of rabies is characterized by symptoms such as hydrophobia and irritability?
Which phase of rabies is characterized by symptoms such as hydrophobia and irritability?
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What is the typical incubation period for rabies?
What is the typical incubation period for rabies?
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What type of virus travels retrograde along peripheral nerves to reach salivary glands?
What type of virus travels retrograde along peripheral nerves to reach salivary glands?
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Which body location has the highest probability of developing rabies following a bite from an infected animal?
Which body location has the highest probability of developing rabies following a bite from an infected animal?
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Which of the following does NOT typically occur during the rabies prodromal phase?
Which of the following does NOT typically occur during the rabies prodromal phase?
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What are Negri bodies associated with in rabies infection?
What are Negri bodies associated with in rabies infection?
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What is the correct dosage of rabies immune globulin (RIG) for a person who is not previously vaccinated, based on body weight?
What is the correct dosage of rabies immune globulin (RIG) for a person who is not previously vaccinated, based on body weight?
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Which route of rabies vaccination is considered equivalent or more effective than the intramuscular route?
Which route of rabies vaccination is considered equivalent or more effective than the intramuscular route?
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When administering rabies immune globulin (RIG) and rabies vaccine, what important consideration must be made?
When administering rabies immune globulin (RIG) and rabies vaccine, what important consideration must be made?
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What is the maximum number of doses for rabies vaccination for someone who has not been previously vaccinated?
What is the maximum number of doses for rabies vaccination for someone who has not been previously vaccinated?
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What is the site of vaccination recommended for adults and older children receiving rabies vaccination?
What is the site of vaccination recommended for adults and older children receiving rabies vaccination?
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Which of the following rabies vaccines is considered the gold standard?
Which of the following rabies vaccines is considered the gold standard?
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How should rabies immune globulin (RIG) be administered with respect to the wound?
How should rabies immune globulin (RIG) be administered with respect to the wound?
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What is the primary type of virus present in rabies vaccines?
What is the primary type of virus present in rabies vaccines?
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Which animals are considered high-risk for rabies exposure?
Which animals are considered high-risk for rabies exposure?
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What should be done immediately after a bite from a potentially rabid animal?
What should be done immediately after a bite from a potentially rabid animal?
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In which case is post-exposure prophylaxis (PEP) withheld?
In which case is post-exposure prophylaxis (PEP) withheld?
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What is the role of rabies immunoglobulins (RIG) in PEP for previously unvaccinated individuals?
What is the role of rabies immunoglobulins (RIG) in PEP for previously unvaccinated individuals?
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What post-exposure action is NOT recommended after a bite from a rabies-suspected animal?
What post-exposure action is NOT recommended after a bite from a rabies-suspected animal?
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What should be done if a human-to-human exposure occurs related to rabies?
What should be done if a human-to-human exposure occurs related to rabies?
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Which of the following is true about rabies exposure and treatment?
Which of the following is true about rabies exposure and treatment?
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Which statement is incorrect regarding rabies and its transmission?
Which statement is incorrect regarding rabies and its transmission?
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What is the main reason why rabies is almost always fatal once symptoms develop?
What is the main reason why rabies is almost always fatal once symptoms develop?
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Which method is NOT used for the ante-mortem diagnosis of rabies in humans?
Which method is NOT used for the ante-mortem diagnosis of rabies in humans?
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What components are included in the post-exposure prophylaxis (PEP) for rabies?
What components are included in the post-exposure prophylaxis (PEP) for rabies?
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What is one of the key post-mortem diagnostic methods for rabies in animals?
What is one of the key post-mortem diagnostic methods for rabies in animals?
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How does the rabies virus typically spread once entering a host?
How does the rabies virus typically spread once entering a host?
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What describes the incubation period for rabies?
What describes the incubation period for rabies?
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What is a common misconception regarding rabies treatment?
What is a common misconception regarding rabies treatment?
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What symptom characterizes 'dumb rabies' in affected individuals?
What symptom characterizes 'dumb rabies' in affected individuals?
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Study Notes
Rabies Virus Structure
- Bullet-shaped with one flat and one tapering end.
- Helical symmetry with coiled nucleoprotein.
- Negative-sense single-stranded RNA genome.
- Enveloped with protruding spikes crucial for host cell attachment.
Rabies: Key Facts
- Serious, infectious, viral disease causing acute fatal encephalomyelitis.
- Zoonotic disease infecting wild and domestic animals.
- Bats are the primary reservoir.
- Dogs are responsible for up to 99% of human transmissions in endemic regions. Other wildlife (foxes, wolves, bats, raccoons) also transmit.
- 100% vaccine-preventable.
- Tens of thousands of annual deaths, mainly in Asia and Africa.
- Children under 15 years account for 40% of rabies cases from animal bites.
- Immediate wound washing with soap and water is crucial for post-exposure prophylaxis (PEP).
- Elimination is possible through dog and cat vaccination and bite prevention.
Main Reservoirs of Rabies
- Dogs
- Cats
- Wild carnivores (foxes, wolves, raccoons, etc.)
- Bats
- Other animals (cattle, camels, horses) are susceptible but don't typically transmit.
Transmission of Rabies
- Primarily through rabid animal bites or scratches, inoculating the virus via saliva.
- Rare non-bite exposures include corneal transplants from infected humans or inhalation of aerosols in bat caves.
- Salivary contamination of skin abrasions or wounds is also a rare transmission route.
Pathogenesis of Rabies
- Virus replicates at the infection site in nerve cell cytoplasm, causing damage and forming Negri bodies (intra-cytoplasmic inclusion bodies).
- Virus travels along peripheral nerves to the CNS (no viremia).
- Retrograde travel along peripheral nerves to salivary glands, eyes, or kidneys for excretion.
Factors Influencing Rabies After Exposure
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Wound severity (depth).
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Bite location.
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Virus quantity (inoculated viral load).
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Virus genotype.
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Timeliness of post-exposure prophylaxis (PEP).
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Probability of developing rabies after a bite from a rabid animal:
- Head: 55%
- Upper limb: 22%
- Lower limb: 12%
Clinical Manifestations of Rabies
- Incubation period: 2 weeks to 16 weeks or longer, depending on distance from bite site to CNS, bite severity, virus amount, and host immunity.
- Three phases:
- Prodromal: mild fever, pain, or paresthesia at bite site.
- Furious rabies (70-80%): strange behavior, irritability, aggression, brainstem encephalitis, hydrophobia, aerophobia, hyperactivity, fluctuating consciousness, death from cardio-respiratory arrest.
- Dumb (paralytic) rabies (20-30%): ascending flaccid paralysis starting at the bite site, pain in affected muscles, death from cardiac or respiratory failure.
- Once symptoms appear, rabies is almost always fatal.
Laboratory Diagnosis of Rabies
- Human Rabies: Diagnosis before clinical disease onset is currently impossible due to lack of viremia and intracellular virus location. Testing occurs after symptoms emerge
- Animal Rabies (Post-mortem):
- Negri bodies in hippocampus and cerebellum.
- Rabies antigen detection by direct immunofluorescence.
- Rabies virus nucleic acid detection by RT-PCR.
- Electron microscopy to visualize bullet-shaped virus particles.
Management of Rabies
- No cure for clinical disease; antiviral agents, interferons, and rabies immunoglobulins are ineffective.
- Prevention through post-exposure prophylaxis (PEP) is crucial due to the long incubation period.
- PEP involves local wound treatment, rabies vaccine, and rabies immune globulin (RIG).
Rabies Post-Exposure Prophylaxis (PEP)
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Based on risk of exposure:
- High Risk: Immediate PEP
- Less Risk: Delayed PEP
- No Risk: No PEP
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High-risk exposure includes unprovoked animal attacks, bites/scratches from high-risk animals (bats, foxes, wolves, stray dogs/cats), contact with bats (bite or non-bite), and bites with anticipated short incubation periods (children, head/neck bites, extensive/deep bites).
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Less-risk exposure relates to bites or mucous membrane exposure from vaccinated domestic animals that can be quarantined for 10 days. PEP can be withheld if the animal survives and shows no signs of rabies.
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Bites from small rodents (rats, mice, rabbits, guinea pigs, hamsters) do not require treatment.
Rabies Post-Exposure Prophylaxis (PEP) Schedule
- Previously unvaccinated: emergency care, rabies immunoglobulins (RIG), rabies vaccine (five doses on days 0, 3, 7, 14, and 28).
- Previously vaccinated: emergency care, no RIG, rabies vaccine (two doses on days 0 and 3).
Rabies Post-Exposure Prophylaxis (PEP): Emergency Care
- No sutures.
- Immediate and thorough wound washing (15 minutes) with soap and water or water alone.
- Disinfection with detergent, 70% ethanol, or iodine.
- Tetanus prophylaxis and antibiotics.
Rabies Post-Exposure Prophylaxis (PEP): Rabies Immune Globulin (RIG)
- Administered as early as possible.
- Infiltrated into and around the wound(s).
- Not administered in the same syringe or site as the vaccine.
- Recommended dose: 20 IU/kg body weight.
- Human (hRIG) or equine (eRIG) derived; hRIG has fewer adverse events.
- A monoclonal antibody (mAB) is licensed in India.
Rabies Post-Exposure Prophylaxis (PEP): Rabies Vaccine
- Previously unvaccinated: five doses of cell-derived vaccine (IM or ID) on days 0, 3, 7, 14, and 28. Intradermal (ID) administration is equally or more effective than intramuscular (IM) and uses less vaccine.
- Previously vaccinated: two doses of cell-derived vaccine (IM or ID) on days 0 and 3.
Rabies Vaccines
- Inactivated virus (fixed rabies virus inactivated by beta-propiolactone).
- Deltoid area is the preferred vaccination site for adults and older children; outer thigh for younger children.
- Never administer in the gluteal area.
Cell-Derived Rabies Vaccines (CCEEVs)
- Inactivated, safer, and more immunogenic than older vaccines.
- Used in both pre-exposure and post-exposure prophylaxis.
- Include human diploid cell rabies vaccine (HDCV), which is the gold standard.
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Description
Explore the structure and essential facts about the rabies virus in this informative quiz. Learn about its unique properties, transmission dynamics, and prevention strategies. Understand the impact of rabies as a serious zoonotic disease affecting both animals and humans.
