Rabies ,microbiology

pathogenesis ,diagnosis, treatment, types

1. RABIES LUBNA S SUBAIR 1 ST SEMESTER M.Sc.BIOTECHNOLOGY CUSAT

2. CONTENTS Importance to know rabies Causative agent Transmission Pathogenesis Types of rabies Diagnosis Management P revention

3. WHY IT IS IMPORTANT TO KNOW ABOUT RABIES? Acute fatal disease that causes fatal encephalomyelitis in all the warm blooded animals including man. It is a zoonotic disease. The disease is invariabble fatal and is the most painful and dreadful of all communicable diseases in which the sick person is tormented at the same time with thirst and fear of water(hydrophobia) Till date there is no accurate cure , once developed the death is inevitable.

4. However the development of the disese can be prevented to a large extent when the animal bites are treated in time and appropriately.

5. Mainly in rural areas and in children India: 20,000 deaths per year India accounts for 36% o f the global human rabies death. Execpt Lakshadeep and Andaman and nicobar all states have reported rabies.

6. CAUSATIVE VIRUS Family- Rhabdoviridae Genus - Lyssavirus Serotype 1 Shape- Bulletshaped Neurotropic Single stranded RNA Non segmented structure Consists of 11,932 nucleotides and encodes 5 proteins.

7. All the rhabdovirus has 2 structural components R ibonucleoproteincore RNP Surrounding envelope The rabies genome encodes 5 proteins Nucleoprotein, N Phosphoprotein , P Matrix protein,M Glycoprotein ,G Polymerase ,L

8. Transmission The virus is found in wild animals and some domestic animals Through their saliva- bites,scratches,licks on wounded skin, mucous membrane. In I ndia dogs are responsible for about 97% of human rabies followed by 2%cats,jackals,and others 1% Rabies is mainly caused by the bite of a rabid dog.

9. TYPES OF RABIES VIRUS Street virus Fixed virus

10. Street virus Naturally found in saliva of infected animals Incubation period is long- 20 to 90 days Cannot be used for vaccine preparation Produce negri bodies

11. NEGRI BODIES An important pathological CNS finding of rabies. An eosinophilic cytoplasmic inclusion Composed of - rabies virus proteins viral RNA Purkinje cells of cerebellum P yramidal neuron of hippocampus

12. FIXED VIRUS Prepared by repeated culture in rabbit brain such that its IP is reduced and fixed Do not produce negri bodies Incubation period is short- 4 to 6 days Can be used for vaccine preparation.

13. PATHOGENESIS

14. 1. Stage of inoculation Period before the virus enter the PNS-incubation period Usually 20-90 days During this period, the rabies virus is present at or close to the site of bite.

15. 2. CNS DISSEMINATION The virus now bind to post synaptic nicotinic acetylcholine receptors ( AChR -N) Then it spreads along the PNS towards the CNS .

16. 3.ENCEPHALITIC FORMATION Inflammation in the CNS region occurs Symptoms- fever,confusion,hallucinations,combativeness ,seizures Autonomic dysfunction- hypersalivation , gooseflesh,cardiac arrhythmia.

17. FEATURES OF RABIES

18. AGGRESSION AND ANGER - virus attack the emotional control centre of brain.

19. HYDROPHOBIA /AEROPHOBIA Swallowing of food or exposure to air-results in involuntary,painful contraction of diaphragm and respiratory muscles

20. HYPERSALIVATION/PHARYNGEAL DYSFUNCTION Due to autonomic dysfunction Produce characteristic foaming at the mouth

21. TYPES OF RABIES 1. Encephalitic/Furious rabies - 80% 2. Paralytic rabies - 20%

22. Paralytic rabies Muscle weakness or flaccid paralysis predominates Early and prominent muscle weakness in bitten area & spreading ,resulting in quadriparesis and facial weakness. Spinchter involvment and sensory disturbances Lacks cardial features like hyperphobia,aerophobia,hyperexcitability etc.

23. DIAGNOSIS One or more of the following 1. Detection of rabies viral antigens by direct fluorescent antibody test (FAT) or by ELISA ,preferably brain tissue (collected post mortem ). 2. Detection by FAT on skin biopsy (ante mortem ) FAT positive after inoculation of brain tissue, saliva or CSF in cell culture, or after intracerebral inoculation in mice or in suckling mice . 3. Detectable rabies-neutralizing antibody titre in the serum or the CSF of an unvaccinated person. 4. Detection of viral nucleic acids by PCR on tissue collected ( brain tissue or skin, cornea, urine or saliva).

24. Broadly classified as - antemortem tests -postmortem tests

25. Antemortem diagnostic tests

26. Ante-mortem specimens for rabies testing include saliva, nuchal skin biopsy and cerebrospinal fluid (CSF). Saliva specimens Collect at least 500μl of saliva into a universal specimen container – often easiest using a syringe or suction device It is recommended to collect a saliva specimen as soon as rabies is considered as part of the differential diagnosis of a patient. CSF specimens Collect at least 500μl of CSF . CSF is typically collected in untreated sterile plastic tubes

27. Nuchal skin biopsy -Section of skin, 5-6 mm in diameter and ≈5-7 mm depth, must be taken from the nape of the neck . - It is important that specimen contained hair follicles and should be of sufficient depth to include the cutaneous nerves at the base of hair follicles .

28. Nape of neck

29. Postmortem diagnosis

30. It is important to conduct laboratory investigations on persons who died from a suspected rabies virus infections. A brain specimen is the preferred specimen Brain specimens Small sections of the both the cerebellum and the cerebrum should be submitted.

31. RT PCR amplification Highly sensitive &specific in rabies virus d etection. In fresh saliva,skin,csf,brain tissues

32. Other methods -MRI of brain-variable and non specific - EEG -non specific results

33. TREATMENT No established treatment Isolating in a quiet roomwith no bright light,noise,convulsions etc. Sedatives can be given to reduce the anxiety Provide intensive cardiac and repiratory support. 99.99% cases are preventable if managed in TIME.

34. STAGES OF TREATMENT 1.Categorization of the wound 2.Wound treatment 3.Vaccination PEP 4.Immunoglobin 5.Counselling the patients

35. Categorisation o f wound Category1 : touching or feeding suspect animals,but skin is intact. Category2 : minor scratches without bleedind or licks on broken area. Category3 : 1 or more bite,scratches,licks on broken areaor exposure to bats.

36. Pre-exposure prophylaxis The people who are considered as high risk group need pre-exposure prophylaxis. These groups include a veterinarian, animal handlers and laboratory workers are people whose activities bring them in contact with rabies virus or rabid animals c-international travelers likely to come in contact of the animals in the rabies threaten areas . All these groups should be treated with rabies vaccines to avoid the chances of sudden infection.

37. Post-exposure prophylaxis If a person is bitten by an animal, the wound and scratches should be washed thoroughly with soap and water to decrease the chances of infection . Post-exposure prophylaxis involved one dose of rabies immune globulin and five doses of rabies vaccine within the 28 days period. Rabies immune globulin contains antibodies from blood donors who were given rabies vaccine. The rabies vaccine works by stimulating a person’s immune system to produce antibodies that neutralize the virus.

38. Managing bitten person Human rabies immune globulin is injected at the bite area immediately because it attacks the virus and slow down or stop viral progression through the nerves . Timing and the ability of the patient to respond by making a good immune response is a key to patient survival . Case management of bitten patients Immediate and thorough cleaning of the wound with soap, followed by ethanol or aqueous iodine. Postexposure prophylaxis (PEP) : administration of rabies immunoglobulin in case of severe exposure (WHO category 3 ). PEP to be applied as soon as possible – vaccines with a potency at least 2.5 IU per single immunizing intramuscular dose according to one of the following schedules Intramuscular schedules ƒ - 1 dose on days 0, 3, 7, 14 and 28. All intramuscular injections to be given into deltoid region .Never inject the vaccine in the gluteal region.

39. This regimen is particularly recommended when no immunoglobulin is required, i.e. when contact consists in nibbling of uncovered skin, minor scratches or abrasions without bleeding, or licks on broken skin. Intradermal schedules . The following intradermal regimens have been shown to be immunogenic ƒ 2-site intradermal method (2-2-2-0-1-1 and 2-2-2-0-2) for use with purified vero cell vaccine (PVRV), purified primary chick embryo cell vaccine (PCECV) and human diploid cell (HCDV) at 0.1 ml per intradermal injection site – days 0, 3 and 7 Intradermal injections must be given by staff trained in this technique. Vaccine vials to be stored between 2 ºC and 8 ºC after reconstitution and total content to be used as soon as possible, at least within 8 hours . Rabies vaccines formulated with an adjuvant should not be administered intradermally . The standard dose per id injection site is 0.1 ml.

40. vaccine A 1-ml syringe and a needle for each intramuscular injection ( intradermal needles and syringes for intradermal vaccination). Vaccine amounts: between 2 and 5 vials, depending on the method used. Only the following vaccines meet WHO safety, potency and efficacy requirements when used for post exposure intradermal treatment of rabies - ƒ human diploid cell vaccine (HDCV ) eg:Rabivac ™ - ƒ purified vero cell vaccine ( PVRV) eg ; Verorab , Imovax , Rabies vero , TRC Verorab ™ - purified chicken embryo cell vaccine ( PCECV) eg ; Rabipur ™.

41. PREVENTION There is no specific treatment for rabies, which is a fatal disease. WHO promotes human rabies prevention through well-targeted postexposure treatment using modern vaccine types and, when appropriate, antirabies immunoglobulin pre-exposure prophylaxis using modern vaccine types for certain professional groups at higher risk and also if vaccines are easily accessible, of children aged under 15 in areas where rabies is hyperendemic increased access of safe and effective rabies vaccines. dog rabies elimination through mass vaccination of dogs and dog-population management.