Rabies Flashcards
What is Rabies?
- Zoonotic viral infectious disease
- Primarily of warm-blooded animals
- Dogs are the main source of human rabies deaths
- -99% of human rabies transmission
- Vaccine-preventable disease
Zoonotic means?
spread from animals to humans
Epidemiology triad of Rabies
- Host: human
Risk factors - Agent: lyssavirus
Mode of transmission
Reservoir: domestic dogs, wild animals, bats - Environment
the population of stray dogs and bats
Rabies virus
- The virus belongs to the Lyssavirus genus of the Rhabdoviridae family
- RNA virus
- Bullet-shaped
- Neurotropic: has an affinity for localizing selectively in nerve tissue
Transmission of Rabies
> Spreads through the saliva of an infected animal: Bite, Scratch, Lick: open wound or mucous membranes (mouth or eyes)
> Human to human transmission: is rare
- Organ transplant
- Direct contact with the saliva of an infected person and mucous membranes or broken skin is possible (however no reported cases of this mode of spread)
> Inhalation of aerosols (containing the virus): also rare
Rabies in animals
You cannot tell if an animal has rabies by just looking at it.
- Strange behavior
- Aggressive
- Timid
- Excessive saliva – foaming at the mouth
- Hydrophobia
- No definitive signs
- Rabid animals may exhibit no symptoms!
Host of Animals
The host of rabies are Humans:
> Those more likely to come into contact with an animal infected with rabies
- -Veterinary workers
- -Hunters
- -Children
> Poverty: people unable to afford to vaccinate their pets; in some countries, post-exposure prophylaxis unaffordable
Global burden of disease
–>95% of human rabies cases are from Africa and Asia
- -Approx. 59 000 deaths in 2016
- -40% of people bitten by suspect rabid animals are children < 15 years
–A neglected disease in ‘developing’ countries:
Preventable but strategies not prioritized
The burden of Rabies in South Africa
–2019: 10 cases of human rabies
all human cases reported were transmitted by bites from dogs or involved likely exposure to dogs
–Additional 6 deaths reported as probable cases of rabies
=cases that presented with a clinical and epidemiological history compatible with a diagnosis of rabies, but for which laboratory investigations were not possible to confirm or exclude the diagnosis
- -56% (9/16) were in children
- -7/16: EC; remainder KZN and Limpopo
Rabies burden of disease 2020 and 2021
2020: 6 lab-confirmed human deaths due to rabies 5: KZN, 1: Limpopo 3 probable cases Lower than 2019 ? Effect of covid-19 ? Missed cases May 2021: 2 cases reported 1 KZN, 1 Limpopo
Global Alliance for Rabies Control
Call to end rabies by 2030
Increase community awareness of the disease and its prevention
Preventable in almost 100% of cases if correct post-exposure preventative treatment is given timeously following exposure to suspected rabid animals
World Rabies Day: 28th September
Clinical presentation of Rabies
The incubation period is typically 2–3 months but may vary from 1 week to 1 year,
-Once clinical symptoms occur, the disease is 100% fatal
Few, sporadic case reports of patients surviving
-Initial symptoms may be non-specific:
general weakness, discomfort, fever, and/or headache
tingling at the bite site
The 2 forms of the Rabies disease
- Furious rabies
2. Paralytic rabies
Furious rabies
- signs of hyperactivity, excitable behavior, hydrophobia (fear of water), sometimes aerophobia (fear of drafts or of fresh air)
- death occurs after a few days due to cardio-respiratory arrest
Paralytic rabies: ≈20% of human cases
- less dramatic and usually longer course than the furious form
- muscles gradually become paralyzed, starting at the site of the bite or scratch
- coma slowly develops, and eventually, death occurs
- a paralytic form of rabies is often misdiagnosed, contributing to the under-reporting of the disease
Diagnosis of Rabies
Diagnosis is made post-mortem
Management of Rabies
Is done through:
- Prevention
- PEP - Post-exposure prophylaxis
Community participation as a management tool of rabies
Remember community engagement as a principle of PHC
Pre-exposure immunization is recommended for people in certain high-risk occupations such as laboratory workers handling live rabies and rabies-related (lyssavirus) viruses; and people (such as animal disease control staff and wildlife rangers) whose professional or personal activities might bring them into direct contact with bats, carnivores, or other mammals that may be infected.
Prevention of Rabies.
-Eliminating rabies in dogs: vaccination
-Awareness of rabies and preventing dog bites
education and information on responsible pet ownership
how to prevent dog bites
immediate care measures after a bite
engagement and ownership of the program at the community level increases reach and uptake of key messages
-Immunization:
Pre-exposure to those at high risk (uncommon)
Animal Diseases Act, 1984
Animal Diseases Act, 1984 (Act No 35 of 1984) law mandates owners to have their pets vaccinated against rabies between the ages of 3 and 7 months, 12 months later, and then every 3 years
Post-exposure prophylaxis (PEP)
Extensive wound washing
=immediate and thorough flushing & washing of the wound for at 15 minutes with soap and water, to wash out the virus
-a course of potent and effective rabies vaccine
ensure patient completes the course
-administration of rabies immunoglobulin (RIG), if indicated
>derived from the blood of humans (hRIG) or horses (eRIG)
>neutralizes the virus at the wound site within a few hours
>passive immunization
Rabies exposure categories as defined by the WHO.
Category I [Touching or feeding animals or being licked on intact skin]: so then no action required, provided exposure history is reliable
Category II [Nibbling of uncovered skin, and minor scratches or abrasions without bleeding]: so then the full course of rabies vaccine is required, RIG not indicates
Category III [Transdermal bite or scratch, Contamination of mucous membrane with saliva from lick, licks on broken skin, exposure due to direct contact with bats]: full course of rabies vaccine plus RIG
Note
Wounds do not have to be large or bleed profusely to be considered category 3
Exposure risk and indications for PEP
Increased risk of rabies if:
The biting mammal is a known rabies reservoir or vector species
The exposure occurs in a geographical area where rabies is still present
The animal looks sick or displays abnormal behaviour
A wound or mucous membrane was contaminated by the animal’s saliva
The bite was unprovoked
The animal has not been vaccinated
Management of the wound and pain.
Antimicrobial if complication from bacterial infection suspected
Analgesic
Do not suture the wound
If the vaccination status of the animal is unknown, what should be done?
then the patient must be vaccinated – do not wait to confirm the vaccine status of the animal.
