Rabies (Rhabdovirus)

Rabies (Rhabdovirus)

1. Epidemiology

Rabies widely spread in Asia and Africa

Rabies is widely distributed across the globe. There are more than > 55,000 people die of rabies each year. 95% of human deaths occur in Asia and Africa.

Most human deaths follow a bite from an infected dog.

30%-60%: children under the age of 15.

2. What is Rabies?

Rabies is a zoonotic disease, caused by a virus.

Transmitted to humans from animals), infects domestic and wild animals

Spread to people through close contact with infected saliva (via bites or scratches)

Once symptoms of the disease develop, rabies is fatal.

3. Rabies - Common facts

Mad Dog biting Humans lead to Rabies.

Hydrophobia (Fear of Water), Saliva of Rabid dogs

4. Rabies- A Zoonotic Disease

Rhabdovirus family; genus Lyssavirus

Enveloped, bullet-shaped virions

Primary reservoirs are wild mammals

6. Any mammal can get rabies.

Raccoons, skunks, foxes and bats

Dogs, cats, cattle and ferrets

Humans 

7. What kind of animals get Rabies?

The rabies virus can infect all mammals.

Mammals are warm-blooded animals that have hair and mammary glands to produce milk for their babies.

Animals like frogs, birds, and snakes do not get rabies.

8. Transmission

Abrasions or scratches on skin.

Mucous membrane exposed to saliva.

Most frequently via deep penetrating bite wounds.

Other routes

        Inhalation in bat infected caves.

        Ingestion of dead /infected animal meat

        Corneal transplantation 

9. Pathogenesis of Rabies

Bite by Rabid dog or other animals

Virus >>> wound site

If untreated  50% will develop rabies.

Rabies can be produced by licks and corneal transplantation.

Virus multiply in muscle, connective tissue, nerves after 48 – 72 hours.

Penetrated nerve endings.

Virus travels through axoplasam toward the spinal cord, at the rate of 3 mm/hour,

Towards the brain

Spread from brain centrifugally to various parts of the body.

Multiplies in the salivary glands, shed in saliva.

Cornea, facial tissues skin.

            Incubation  1 – 3 months.

May be average  from 7 days to 3 years.

Stages of the disease.

            Prodrome

            Acute encephalitis.

            Coma / Death.

10. Category – WHO

Category I: touching or feeding suspect animals, but skin is intact

Category II: minor scratches without bleeding from contact, or licks on broken skin

Category III: one or more bites, scratches, licks on broken skin, or other contact that breaks the skin; or exposure to bats

11. Clinical Findings

Bizarre behavior, Agitation, Seizures

Difficulty in drinking

Patients will be able to eat solids

Afraid of water  - Hydrophobia

Even sight or sound of water disturbs the patient.

But suffer with intense thirst.

Spasms of Pharynx produces choking, Death in 1-6 d. Respiratory arrest / Death

12. Symptoms

Headache, fever, sore throat

Nervousness, confusion

Pain or tingling at the site of the bite

Hallucinations

◦       Seeing things that are not really there

Hydrophobia

◦       “Fear of water" due to spasms in the throat

Paralysis

◦       Unable to move parts of the body

Coma and death

13. CLINICAL  MANIFESTATIONS

1 – Non  specific  prodrome

2 – Acute  neurologic  encephalitis

      Acute  encephalitis

      Profound  dysfunction  of  brainstem

3 – Coma

4 - Death  (  Rare  cases à  recovery )

14. Diagnosis

              Current diagnostic tools are not suitable for detecting rabies infection before the onset of clinical disease, and unless the rabies-specific signs of hydrophobia or aerophobia are present, clinical diagnosis may be difficult. Human rabies can be confirmed intra-vitam and post mortem by various diagnostic techniques that detect whole viruses, viral antigens, or nucleic acids in infected tissues (brain, skin, urine, or saliva).

15. PREVENTION

Preexposure   Prophylaxis

Postexposure  Prophylaxis

Ist Vaccine for Rabies

Prepared by Pasteur  by drying various periods pieces of spinal cord of Rabbits infected with fixed virus

1885 Joseph Meister 9 year boy vaccinated 13 injections were given

Patient saved

Preexposure vaccination

Indicated in

            Laboratory workers

           Veterinarians and technical staff

           Bat handlers

            Children

Vaccines

•       Sample vaccine

    Contain 5 % suspension. Of infected sheep brain,  ( infected with fixed virus), inactivated with Phenol at 37⁰c

- Used in Developed countries neural complications

Neural Vaccines*

Class I  slight risk

Class II Moderate risk

Class III Great risk

Nerual vaccines may cause Neuroparlytic complications, Laundry’s type ascending paralysis

•          Dose is regulated according to grade/class of bites

•          Many countries do not use in view of neurological complications

HUMAN RABIES cell culture vaccines

Vaccine:

    Human  diploid  cell  vaccine (HDCV)

    Cell culture vaccines:

    Purified  chick  embryo  cell  vaccine (PCEC)

    Purified  Vero  cell  vaccine (PVRV)

    Purified  duck  embryo vaccine (PDEV)

Post exposure Prophylaxis

The vaccination is given on 0, 3, 7, 14, and 30

Injected on deltoid region

  : IM/ID

  : Not to be given in the gluteal region

Cell culture Vaccines in – commonly prescribed

1 Human diploid cell vaccine.

2 Purified chick embryo cell vaccine

3.Purified Vero cell vaccine