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Questions and Answers
What is the implication of an R0 value greater than 1 in a population?
Which of the following statements is true regarding the R0 of rabies in humans?
What factor largely contributes to the rabies R0 being greater than 1 in dogs?
What was a contributing factor in the five rabies deaths reported in the U.S. in 2021?
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Which of the following animals is NOT identified as a rabies reservoir in Canada?
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What was the significance of Pasteur's observation regarding old bacterial cultures?
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How did Joseph Meister contribute to the development of the rabies vaccine?
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What is the role of human rabies immune globulin (HRIG) in postexposure prophylaxis?
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In what year did Louis Pasteur create the first rabies vaccine?
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What is the R0 value indicating when R0 is less than 1?
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What was the vaccination protocol for the 1911 rabies vaccine developed by H.K. Mulford?
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What does postexposure prophylaxis (PEP) for rabies involve?
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What procedure was used to create the first rabies vaccine by Pasteur?
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What percentage of human rabies cases are attributed to dog bites?
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In which regions do the majority of human rabies deaths occur?
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How long can the rabies virus take to travel from the peripheral nervous system to the brain?
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What is the main characteristic of the rabies virus's genome?
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Which historical figure suggested a preventative measure for rabies in puppies?
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What is the rabies virus primarily inactivated by?
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Which animal is not typically involved in the zoonotic transmission of rabies?
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What role did the goddess Gula play in ancient Babylonian culture concerning rabies?
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What is the leading cause of human rabies cases worldwide?
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What characteristic of dogs contributes to the higher R0 value for rabies in this species?
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What does the R0 of rabies in humans signify in the context of disease transmission?
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Which regions account for approximately 99% of human rabies deaths?
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Which of the following animals is a recognized rabies reservoir in Canada?
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What type of virus is rabies classified as?
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What was a contributing factor to the rabies deaths reported in the U.S. in 2021?
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What historical preventative measure did Columella describe pertaining to rabies?
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How long can the rabies virus take to travel from the peripheral nervous system to the brain?
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What historical event is associated with the first rabies case in Canada?
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Which of the following measures can inactivate the rabies virus?
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What was a significant action taken by the Babylonian king Adadapla-iddina related to rabies?
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In which continents is rabies primarily transmitted, excluding Antarctica?
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What was the method used by Pasteur to create the first rabies vaccine?
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What was the vaccination protocol for the rabies vaccine developed by H.K. Mulford in 1911?
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What immediate treatment is provided alongside the rabies vaccine in postexposure prophylaxis?
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What impact would the absence of postexposure prophylaxis (PEP) have on rabies-related deaths?
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What phenomenon did Pasteur observe in bacterial cultures that led to his development of vaccines?
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What does R0 indicate in relation to rabies transmission among dogs?
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How many inoculations did Joseph Meister receive after being bitten by a rabid dog?
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What is the role of postexposure prophylaxis (PEP) for rabies in humans?
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Study Notes
Rabies: A Deadly Zoonotic Disease
- Rabies is one of the most deadly zoonotic diseases, responsible for approximately 60,000 deaths worldwide each year, primarily affecting children in developing countries.
- Dog bites are responsible for 95% of human rabies cases.
- Almost all human rabies deaths occur in Africa and Asia, where dog rabies control is poor.
- Despite its danger, tools exist to eradicate rabies.
Ancient History of Rabies
- The Eshnunna Code (2300 BC) mandated that the owner of a rabid dog was responsible for its containment.
- Babylonian king, Adadapla-iddina (1068-1047 BC), built a temple to the goddess Gula, a healer and protector from rabies.
- Aristotle (384-322 BC) observed that rabid dogs become irritable and transmit the disease through bites.
- Columella (60 AD) suggested cutting puppies' tails as a preventative measure against rabies.
Rabies Transmission and Global Distribution
- Rabies is spread primarily through the saliva of infected animals, most commonly rabid dogs.
- Rabies affects all continents except Antarctica.
- Asia, Africa, and India experience the highest number of human deaths from rabies, with approximately 59,000 deaths per year.
- In Europe and the Americas, human rabies deaths and transmissions from dogs are relatively low due to vaccination efforts.
- Wildlife, such as bats, foxes, skunks, and raccoons, are the primary sources of rabies transmission in these regions.
Rabies Virus
- The rabies virus is an RNA virus belonging to the family Rhabdoviridae.
- Its genome consists of 12 kb of negative-sense RNA.
- Species-specific variants exist for different animals, including bats, skunks, and foxes.
- The virus is environmentally labile and can be inactivated by heat (50°C for 15 minutes), sunlight, and desiccation.
Rabies Infection and Symptoms
- The rabies virus travels from the periphery of the nervous system to the brain, taking 3-12 weeks.
- Once in the brain, the virus replicates rapidly.
- The virus then spreads to salivary glands, leading to the shedding of the virus in saliva.
- Clinical symptoms of rabies develop quickly, leading to death within a week.
- Treatment for rabies must be administered before clinical signs appear.
- There is minimal to no transmission during the preclinical phase of rabies.
Detection and Control
- The long incubation period of rabies makes clinical detection difficult.
- Targeting affected dogs is crucial for rabies control.
Rabies Vaccination: Origins and Development
- Louis Pasteur (1885) developed the first rabies vaccine using attenuated rabies virus from rabbits.
- He used spinal cord tissue from infected rabbits, ground and dried, to create a series of progressively more virulent samples for vaccination.
- The first person to receive the rabies vaccine was Joseph Meister, who was bitten by a rabid dog in 1885. He received 13 inoculations over 3 weeks and did not develop rabies.
The Mulford Rabies Vaccine (1911)
- H.K. Mulford, a Philadelphia drug company, developed a rabies vaccine protocol that was accessible to doctors with no prior experience.
- The protocol consisted of 25 injections of rabies vaccine, with progressively more potent doses.
Rabies Vaccination Today
- Rabies vaccination of dogs helps prevent infection in animals.
- In humans, rabies vaccination is a crucial part of post-exposure prophylaxis (PEP) after a bite or scratch from a potentially rabid animal.
Post-exposure Prophylaxis (PEP)
- PEP for rabies involves administering a dose of human rabies immune globulin (HRIG), which provides immediate antibodies.
- PEP also includes a series of rabies vaccinations on the day of exposure and on days 3, 7, and 14.
- The World Health Organization estimates that 29 million doses of PEP are administered globally each year, potentially preventing 3 million deaths.
Rabies Transmission and R0
- Rabies has an R0 (basic reproduction number) of greater than 1 in dogs, due to the high social interaction and frequent biting amongst dogs.
- R0 in humans is considered zero because humans are considered a dead-end host.
- Rabies control strategies focus on vaccinating dogs and animals, as human-to-human transmission is extremely rare.
Rabies in Canada
- Charles Lennox, 4th Duke of Richmond, is thought to be the first recorded rabies case in Canada in 1819.
- Rabies virus reservoirs in Canada include arctic foxes, red foxes, skunks, raccoons, and bats.
Rabies in the US (2021)
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In 2021, there were five recorded rabies deaths in the US.
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The deaths highlight the importance of rabies vaccination and awareness of the risk of potentially rabid animals.
Rabies: A Deadly Zoonotic Disease
- Rabies is one of the most deadly zoonotic diseases, responsible for approximately 60,000 deaths globally each year, with a large majority occurring in children residing in developing countries.
- Dog bites are the primary cause of human rabies cases, accounting for 95% of infections.
- The majority of human rabies deaths occur in Africa and Asia, where dog rabies control is poor.
- Rabies is a preventable disease with readily available tools for eradication.
Historical Perspective
- The Eshnunna Code (2300 BC) held the owner of a rabid dog responsible for containing the affected animal.
- Babylonian King Adadapla-iddina (1068-1047 BC) built a temple dedicated to the goddess Gula, known for her healing abilities and protection against rabies.
- Ancient Greek philosopher Aristotle (384-322 BC) described rabies as a form of madness in dogs that transmitted disease through bites.
- Roman author Columella (60 AD) suggested cutting the tails of puppies as a preventative measure against rabies.
Rabies Transmission and Distribution
- Rabies is primarily transmitted by rabid dogs and is present on all continents except Antarctica.
- The highest number of human rabies deaths occur in Asia, Africa, and India, with an estimated 59,000 fatalities each year.
- Europe and the Americas experience fewer human rabies deaths, likely due to effective dog vaccination programs.
- Transmission in Europe and the Americas primarily occurs through wildlife, including bats, foxes, skunks, and raccoons.
Rabies Virus: Characteristics and Spread
- Rabies is caused by an RNA virus belonging to the Rhabdoviridae family.
- The virus has a genome of 12 kb negative sense RNA and exhibits species-specific variants, such as those found in bats, skunks, and foxes.
- Rabies virus is environmentally labile and can be inactivated by heat (50°C for 15 minutes), sunlight, and desiccation.
Rabies Virus Progression and Clinical Symptoms
- The rabies virus travels from the peripheral nervous system to the brain over a period of 3 to 12 weeks.
- Rapid viral replication occurs in the brain, followed by centrifugal spread to the salivary glands and saliva.
- Clinical symptoms of rabies typically lead to death within a week of onset.
- Treatment is most effective prior to the development of clinical signs, as minimal transmission occurs during the pre-clinical phase.
The Challenge of Long Incubation Periods
- The lengthy incubation period of rabies makes case detection challenging, particularly during the long preclinical phase.
- Detecting clinical rabies can be difficult, further complicating control efforts.
Louis Pasteur and the Development of the Rabies Vaccine
- Louis Pasteur's observations of attenuated bacterial cultures in chicken cholera led to the development of the first rabies vaccine.
- Pasteur's rabies vaccine involved passing the virus through rabbits, attenuating its virulence while retaining its ability to induce an immune response.
- The vaccine was administered as a series of progressively more virulent rabies samples, starting with highly attenuated forms.
- In 1885, Joseph Meister, a young boy bitten by a rabid dog, was successfully treated with Pasteur's vaccine, marking a significant triumph in the fight against rabies.
Rabies Vaccination: Early Protocols and Advancements
- The first rabies vaccine for humans was developed in 1911 by H. K. Mulford, a Philadelphia drug company.
- The vaccine protocol involved 25 injections over 18 days, with each dose increasing in virulence to gradually build immunity.
Prevention and Treatment of Rabies
- Dog vaccination is a crucial step in preventing rabies infection.
- Post-exposure prophylaxis (PEP), consisting of a dose of human rabies immune globulin (HRIG) and a series of rabies vaccines, is essential for individuals exposed to the virus.
- PEP should be initiated immediately following rabies exposure, typically with a first dose of HRIG and additional vaccination doses on days 3, 7, and 14.
Rabies Control: The Importance of Public Health Measures
- The WHO estimates that 29 million doses of PEP are administered globally each year, potentially preventing 3 million deaths due to rabies.
- Rabies is highly transmissible, with an R0 (basic reproduction number) greater than 1 in dogs, indicating that each infected dog can transmit the virus to more than one other dog.
- Humans are considered dead-end hosts for rabies, meaning they cannot spread the virus to other humans.
Rabies in Canada: Historical Perspective and Current Landscape
- The first recorded rabies case in Canada involved Charles Lennox, the 4th Duke of Richmond, in 1819.
- Current wildlife reservoirs for rabies in Canada include artic foxes, red foxes, skunks, raccoons, and bats.
- Canada experienced a significant decrease in rabies cases in 2024.
Rabies Fatalities in the United States
- In 2021, five deaths due to rabies were reported in the United States.
- The majority of these cases involved individuals who were not vaccinated, highlighting the importance of vaccination.
- One case involved a traveler who was bitten by a rabid dog in the Philippines and died in New York.
Key Points to Remember
- Rabies is a deadly zoonotic disease with high mortality rates, particularly in developing countries.
- Dog bites are the leading cause of human rabies infection.
- Rabies is entirely preventable through vaccination and post-exposure prophylaxis (PEP).
- The R0 for rabies is greater than 1 in dogs, highlighting the importance of control measures like vaccination.
- Humans are dead-end hosts for rabies, meaning they cannot spread the virus to other humans.
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Description
This quiz explores the deadly zoonotic disease, rabies, including its historical significance, transmission methods, and global distribution. Learn about ancient practices for prevention and the contemporary challenges in controlling rabies, especially in developing nations. Test your knowledge on the facts and myths surrounding this lethal disease.
