Rabies

Learning outcomes: At the end of this lecture the students will be able to: Define rabies, its epidemiology, mode of transmission. Describe symptoms, diagnosis, treatment and prognosis. Discuss its preventive measures both in humans and animals.

Definition Rabies: An infectious viral disease that causes acute inflammation of brain in humans and other warm-blooded animals. It is almost always fatal after onset of clinical symptoms. Agent: The rabies virus - genus Lyssa.

Epidemiology & Geographical distribution: Rabies is a neglected disease that can affect both domestic and wild animals Spread to people by bites/ scratches of infected animals. Up to 99% of cases, dogs are responsible for rabies virus transmission to humans Rabies is present on all continents, except Antarctica Over 95% of human deaths occur in Asia and Africa

Mostly affects poor and vulnerable populations in remote rural areas Globally, rabies deaths are rarely reported Children between 5–14 years are frequent victims Every year, more than 15 million people worldwide receive a post-bite vaccination preventing hundreds of thousands of rabies deaths annually

Case definitions of humans rabies by WHO Suspected: A case that is compatible with the clinical case definition Probable: A suspected case plus history of contact with a suspected rabid animal Confirmed: A suspected case that is laboratory-confirmed

Transmission Virus enters peripheral nervous system of humans via wound (does not enter blood stream). Then travels toward CNS causing inflammation of spinal cord and brain (transverse myelitis & encephalitis). Once the symptoms develop, treatment is almost never effective and mortality is over 99%.

History An ancient disease, term rabies is derived from Latin word rabies, meaning “madness” and Greeks word lyssa, - Lyssavirus. Aristotle (300BC) noted that rabies affects dogs and animals bitten by dogs. (The dog owners in the Babylonian city (present Iraq) fined heavily for deaths caused by their dogs biting people).

Incubation Period: 2 to 12 weeks in humans but as short as 4 days and longer than 6 months have been documented, Symptoms depend on the, Location of bite Severity of wound Amount of virus introduced

Symptoms: The incubation period for rabies is typically 1–3 months but may vary from 1 week to 1 year, dependent upon factors such as the location of virus entry and viral load. Initial symptoms include fever with pain, tingling, or burning sensation at the wound site. As the virus spreads to the central nervous system, progressive and fatal inflammation of the brain and spinal cord develops.

Symptomatic patients:

Diagnosis: Currently there are no suitable tools for detecting rabies infection before the onset of clinical disease. Rabies specific signs are hydrophobia / aerophobia. Human rabies can be confirmed during life and post mortem by various diagnostic techniques that detect whole viruses, viral antigens, or nucleic acids in infected tissues (brain, skin, urine, or saliva).

Types of contact are: Category I – touching or feeding animals, licks on the skin. Category I no treatment is required. Category II – nibbling of uncovered skin, minor scratches or abrasions without bleeding, licks on broken skin. Require immediate vaccination. Category III – single or multiple bites/scratches with licks. licks. Require immediate PEP and rabies immune globulin.

Management and Prevention: Post-exposure prophylaxis consists of: Local treatment of the wound Anti rabies vaccination

1. Treatment of wound: Wash wound immediately and thoroughly for at least 15 minutes with soap and water, (soap may denature and destruct the virus) Then apply antiseptic lotion Leave the wound open (rabies wound is not stitched as this could expose nerve endings to rabies virus, if suturing is necessary, ensure that immunoglobulin has been applied locally) Give tetanus toxoid (TT) vaccination booster Give antibiotics for secondary infection

Rabies vaccine by Louis Pasteur Louis Pasteur developed live attenuated rabies vaccine by growing the virus in rabbits, then drying the affected nerve tissue to weaken the virus. In 1885, Pasteur administered the vaccine to Joseph Meister (a 9-year-old boy) who had been attacked by a rabid dog. The boy survived.

Louis Pasteur and Joseph Meister, the1st person to receive Pasteur's rabies vaccination.

Rabies Vaccination Vaccination against rabies is is used in two distinct situations: Pre - exposure vaccination: to protect people at risk. Post-exposure prophylaxis: to prevent rabies after exposure. Every year, more than 15 million people worldwide receive post-exposure preventive regimen.

There are two types of rabies vaccine PEP I. Rabies Immunoglobulin Human Rabies lmmunoglobulin (HRIG) Equine Rabies lmmunoglobulin (ERIG)  II: Anti rabies vaccines. Human diploid cell vaccine (HDCV) and Purified chick embryo cell culture vaccine (PCECV)

Rabies Immunoglobulin( Passive immunization) Human rabies immunoglobulin are used for category II & III. Administered just before or shortly after 1st dose of ant rabies vaccine. Can be administered till 7th day Full dose or as much as feasible should be administered into and around the wound site, remainder should be injected IM at a distant site from active vaccine administration. Dosage HRIG is 20 IU/kg, ERIG 40 IU/kg body wt.

2. Anti Rabies vaccine available in Pakistan Active immunisation Purified vebro cell vaccine (PVRV) 0.5ml IM/ID Purified chick embro cell vaccine (PCEVC) 0.1ml IM/ID Purified Duck em bryo Cell Vaccine (PDEV 0.1ml IM/ID

Intradermal regimens: WHO recommends the following intradermal regimen. 0.1 ml of vaccine on 2 - site intradermal (2-2-2-0- 2) on day o, 3, 7, 28 Rabies for previously vaccinated peoples Local treatment of wound ‹ 2 (0.1 ml at 1 site) doses of Cell Culture Vaccine be given on days 0 and 3 IM/ID. No Rabies Immunoglobulin is required

‹ The 2-1-1 regime intramuscular regime 4 dose regimen is administered as 2 doses on day 0 (1 dose in right and left deltoid muscles. 1 dose on day 7th & 1 dose on day 21 in deltoid muscle. Vaccination is not contraindicated in pregnancy and breast feeding. Different studies confirm that anti rabies vaccination are safe during pregnancy. 

Treatment after rabies development 100% mortality after development of symptoms. Only palliative therapy is given at this stage: Pain relief (morphine) Reduction of spasms (muscle relaxants, diazepam). Isolation Staff should be preferably vaccinated, but not obligatory

Prognosis In unvaccinated humans, rabies is almost always fatal after neurological symptoms have developed Vaccination after exposure, PEP, is highly successful in preventing the disease if administered promptly, (in general within 6 days of infection) PEP is 100% effective against rabies 

Prevention

September 28 is World Rabies Day; World Rabies Day is designed to raise awareness about both human and animal rabies by.   Information Prevention Elimination of the disease

Rabies in Pakistan: Rabies is endemic in Pakistan and is not notifiable. Dogs are the main vector. There is a no proper surveillance system Limited access to up-to-date rabies vaccines Inadequate resources and poor political support Weak in collaboration between government departments and health authorities, livestock & veterinaries

WHO response to rabies in Pakistan WHO, in collaboration with provincial health authorities, is working to develop dog bite treatment centres to strengthen post-exposure prophylaxis. Plans are developed to involve other sectors, such as livestock authorities and veterinary research centres

WHO's strategy for rabies control main features Mass awareness on transmission, prevention and self-protection Establishment of rabies treatment centres at district headquarters hospital Training of health-care providers on management and treatment of dog bites Cost-effective and efficacious anti-rabies vaccines in rabies treatment centres

Enactment and enforcement of laws relating to pet vaccination To decrease the stray dog population through use of bait, vaccination and dog elimination. Research and surveillance monitor dog bites, dog rabies and human rabies through the use of the existing death reporting system

Baits with vaccine for oral rabies animal vaccination.

Rabies in the animals

Rabies in animals like dogs, cats and horses leads to, No way to test rabies virus in live animals. The only way to test rabies is by examination of brain tissue of dead animal Rabies in animals like dogs, cats and horses leads to, Changes in behavior Aggressiveness Difficulty in swallowing Hyper salivation Convulsions The animal usually dies within 7 – 14 days

Targeted removal of unvaccinated, ownerless dogs Mass vaccination campaigns is most effective measure for controlling rabies. Veterinary surveillance of rabies and laboratory submission of reports of suspected animal cases. Full incorporation of rabies control activities in all levels of the health services and aligning them with public health programmes such as EPI.

Key Facts Rabies is a vaccine-preventable viral disease which occurs in more than 150 countries and territories. Dogs are the main source of human rabies deaths, contributing up to 99% of all human rabies Rabies elimination is feasible through vaccination of dogs and prevention of dog bites. Infection causes tens of thousands of deaths every year, mainly in Asia and Africa.

40% of people bitten by suspect rabid animals are children under 15 years of age. Immediate, thorough wound washing with soap and water after contact with a suspect rabid animal is crucial and can save lives. WHO in collaboration with other Agencies have established a global “United Against Rabies” collaboration to provide a common strategy to achieve "Zero human rabies deaths by 2030".

Question A 15 year old farmers son was brought to Casualty badly bitten by a stray dog on his left leg. According to a report the stray dog population has been greatly increased in Hayatabad. The Authorities had made a plan to reduce their population. How the doctor will manage the child. Write down the steps taken by the authorities to reduce this population

MCQs Treatment for rabies exposure requires; Anti viral vaccine and rabies immune globulins Anti rabies vaccination and rabies immune globulin Rabies antitoxins and tetanus toxoid Injection of anti rabies vaccine and injectable antibiotics Anti tetanus injection and rabies immune globulin Key: b

The causative agent of is rabies? Bacteria Protozoa Virus Fungi Prions Key: Virus

Thank you