RABIES community medicine japnese encephalitis.pptx

Rabies

1. DEPARTMENT OF COMMUNITY MEDICINE . Sharda Nagwanshi – 86 . Shashank Mehar – 87 . Shilpa Prithwani – 88 . Shiv Ram Choyal – 89 . Shreeji Choudhury - 90

2. RABIES

3. Definition Rabies, also known as hydrophobia is an acute, highly fatal viral disease of the central nervous system, caused by Lyssavirus type 1. It is primarily a zoonotic disease of warm- blooded animals, particularly carnivorous such as dogs, cats, jackals and wolves. It is transmitted to man usually by bites or licks of rabid animals. Classical hydrophobia is clinically characterized by a long and variable incubation period, a short period of illness due to encephalomyelitis ending in death, despite intensive care. It is the only communicable disease of man that is always fatal.

4. Epidemiological determinants AgentFactors AGENT: The causative agent (Lyssavirus type 1) is a bullet shaped neurotropic RNA containing virus It belongs to the family Rhabdoviridae serotype 1 and is the causative agent of rabies. Serotype 2, 3 and 4 are rabies-related but antigenically distinct viruses they cause rabies like disease in man and animals.

5. Rabies virus particles contain two distinct, major antigens a glycoprotein (G protein) antigen from the virus membrane and an internal nucleoprotein antigen. The glycoprotein seems to be the only antigen capable of inducing the formation of virus-neutralizing antibodies. The presence of neutralizing antibodies in the blood of man and animals is considered an index of protection against infection with rabies virus Recently, surface glycoprotein of rabies virus has been cloned and expressed in E coli in a bid to develop genetically engineered rabies vaccine.

6. The virus is excreted in the saliva of the affected animals The virus recovered from naturally occurring cases of rabies is called " street virus" . It is pathogenic for all mammals and shows a long variable incubation period (20-60 days in dogs). Serial brain-to-brain passage of the street virus in rabbits modifies the virus such that its incubation period is progressively reduced until it becomes constant between 4-6 days. Virus isolated at this stage is called a fixed virus A "fixed" strain of virus may be defined as one that has a short, fixed and reproducible incubation period (4-6 days) when injected intracerebrally into suitable animals. It does not form Negri bodies, It no longer multiplies in extra-neural tissues. The fixed virus is used in the preparation of antirabies vaccine. There is evidence that fixed virus can be pathogenic for humans and mammals under certain conditions, as for example parenteral injection of antirabies vaccine inadequately inactivated.

7. SOURCE OF INFECTION The source of infection to man is the saliva of rabid animals. In dogs and cats, the virus may be present in the saliva for 3-4 days (occasionally 5-6 days) before the onset of clinical symptoms and during the course of illness till death. HostFactors All warm blooded animals including man are susceptible to rabies. Rabies in man is a dead-end infection, and has no survival value for the virus. Laboratory staff working with rabies virus, veterinarians, dog handlers, hunters and field naturalists face bigger risks of rabies than do general public.

8. Mode of transmission People are infected following a deep bite or scratch by an infected animal. Dogs are the main host and transmitter of rabies. Bats are the source of most human rabies deaths in the United States of America and Canada. Bat rabies has also recently emerged as a public health threat in Australia, Latin America and western Europe. However in these regions the number of human deaths due to bat rabies remains small compared to deaths following dog bites.

9. Transmission can also occur when infectious material usually saliva-comes into direct contact with human mucosa or fresh skin wounds. Human-to-human transmission by bite is theoretically possible but has never been confirmed Rarely, rabies may be contracted by inhalation of virus- containing aerosol or via transplantation of an infected organ. Ingestion of raw meat or other tissues from animals infected with rabies is not a source of human infection.

10. IncubationPeriod The incubation period in man is highly variable, commonly 1-3 months following exposure but may vary from 7 days to many years . The incubation period depends on the site of the bite, severity of the bite, number of wounds, amount of virus injected, species of the biting animal, protection provided by the clothing and treatment undertaken, if any. In general, incubation period tends to be shorter in severe exposures and bites on face, head, neck and upper extremities and bites by wild animals.

11. Pathogenesis Rabies virus replicates in muscle or connective tissue cells at or near the site of introduction before it attaches to nerve endings and enters peripheral nerves. It spreads from the site of infection centripetally via the peripheral nerves towards the central nervous system; most likely it " ascends " passively through the nerve associated tissue space. Following infection of the central nervous system, the virus spreads centrifugally in peripheral nerves to many tissues, including skeletal and myocardial muscle, adrenal glands and skin. The salivary glands invasion is crucial for the transmission of the virus to another animal or human.

12. Rabies in Man

13. Rabies in man is called hydrophobia. It begins with prodromal symptoms such as headache, malaise, sore throat and slight fever lasting for 3- 4 days. 80% of patients complain of pain or tingling at the site of the bite. The prodromal stage is followed by widespread excitation and stimulation of all parts of nervous system involving the sensory system then the motor system.

14. The patient is intolerant to noise, bright light or a cold draught of air. Aerophobia (fear of air) fanning a current of air across the face causes violent spasms of the pharyngeal and neck muscles. Dilatation of the pupils and increased perspiration, salivation and lacrimation (sympathetic). Mental changes include fear of death, anger, irritability and depression. Symptoms are progressively aggravated and swallowing of liquid become unsuccessful (hydrophobia). Aerophobia & hydrophobia are pathogenomic of rabies .

15. Diagnosis On the basis of history of bite by a rabid animal and characteristic signs and symptoms (hydrophobia). It is confirmed by antigen detection using immunofluorescence of skin biopsy, and by virus isolation from saliva and other secretions.

16. T r e a t me n t There is no specific treatment for rabies. Case management includes the following procedure : (a) patient should be isolated in a quiet room protected from external stimuli such as bright light, noise or cold draughts which may precipitate spasms or convulsions.

17. Use of sedatives : Morphia in doses of 30- 45 mg may be given repeatedly, it is well tolerated & there appears no reason to restrict the administration of a drug which does so much to allay acute suffering. If spastic muscular contractions are present use drugs with curare- like action. Ensure hydration and diuresis Intensive therapy in the form of respiratory and cardiac support may be given.

18. This may be considered under 3 heads. P o s t - exposure prophylaxis. Pre- exposure prophylaxis. P o s t - exposure treatment of previously vaccinated. PREVENTION OF HUMAN RABIES

19. P O S T - EXPOSURE PROPHYLAXIS 1. General consideration Aim of post- exposure prophylaxis is to neutralise the inoculated virus before it can enter the nervous system. Administration of a single dose of rabies immunoglobulin if indicated with a course of vaccine, together with local treatment of the wound is the best specific prophylactic treatment after exposure to rabies.

20. 2. Local treatment of wound Local wound treatment is of utmost importance as it can reduce chances of developing rabies by upto 80% The purpose is to remove as much virus as possible from the site of inoculation before it can be absorbed on nerve endings. a) Cleansing : Immediate flushing and washing the wounds, scratches and the adjoining areas with plenty of soap and water, under a running tap, for at least 15 minutes.

21. Chemical treatment : tincture or 0.01% aqueous solution of iodine or povidone iodine. Suturing : Bite wounds should not be immediately sutured to prevent additional trauma which may help spread the virus into deeper tissues.If needed it should be done 24- 48 hours later. d) Use of antibiotics and anti- tetanus measure

22. 3. Immunization Cell- culture vaccine (CCV) and embryonated egg-based vaccine (EEV) for pre- exposure as well as post- exposure prophylaxis. CCEEVs consist of rabies virus that has been propagated in cell substrates such as human diploid cells (embryonic fibroblast cells), fetal rhesus diploid cells, Vero cells (kidney cells).etc. All CCEEVs should comply with the WHO recommended potency of 2.5 IU/ im dose.

23. Categories of contact and recommended post- exposure prophylaxis (PEP) The guidelines for the post- exposure treatment by the WHO

24. All category II and III exposures assessed as carrying a risk of developing rabies require P E P . This risk is increased if : the biting mammal is a known rabies reservoir or vector species, the animal looks sick or has an abnormal behaviour; a wound or mucous membrane was contaminated by the animal’s saliva the bite was unprovoked the animal has not been vaccinated.etc. P o s t - exposure prophylaxis may be discontinued if the suspected animal is proved free of rabies or remains healthy throughout a period of 10 days observation.

25. Intramuscular administration of vaccine for post- exposure prophylaxis schedule is based on injecting 1 ml or 0.5 ml into the deltoid muscle (or anterolateral thigh in children aged <2 years) Essen regimen: the 5- dose regimen prescribes 1 dose on each Day 3 7 14 28 Dose: one IM dose (1.0 or 0.5 ml) into deltoid (or thigh) Zareb regimen : the 4- dose multisite regimen 2 doses on day (1 in each of the 2 deltoid or thigh sites) followed by 1 dose on each of days 7 and 21,

26. 2- site intradermal regimen ( 2 + 2 + 2 + + 2 ) days 0, 3 , 7 , 14 , 28 Dose : one ID dose = one fifth of IM dose (0.1 ml) ID per site P o s t - exposure prophylaxis for previously vaccinated individuals: CCEEV 1 dose IM or CVV ID on days & 3 is sufficient. OR Single- visit 4- site ID regimen consisting of 4 injections of 0.1 ml equally distributed over left and right deltoids or thighs

27. Immunization of immunocompromised individuals series of 5 doses IM CCEEV in combination with wound management and local infiltration with human rabies immunoglobulin Rabies immunoglobulin for passive immunization is administered only once The dose of human rabies immunoglobulin is 20 IU/kg body weight; for equine immunoglobulin it is 40 IU/kg body weight. Most new equine immunoglobulin preparations are potent, highly purified, safe and considerably less expensive.

28. Guide for pre- exposure prophylaxis (PrEP) Recommended for anyone at increased risk of exposure to rabies virus IM doses of 1 ml or 0.5 ml, depending on the vaccine type, or intradermal administration of 0.1 ml volume per site (one site each day) given on days 0, 7 and 21 or 28. P e riodi c booster injections recommended for people who are at occupational risk or frequent risk of exposure. veterinarians and animal health officers should have serological monitoring every 2 years.

29. Contraindications and precautions P e o p l e taking chloroquine for malaria treatment or prophylaxis may have a reduced response to intradermal rabies vaccination. These patients should receive the vaccine intramuscularly.

30. Contraindications and precautions P e o p l e taking chloroquine for malaria treatment or prophylaxis may have a reduced response to intradermal rabies vaccination. These patients should receive the vaccine intramuscularly.

31. RABIES IN DOGS

32. RABIES IN DOGS INCUBATION PERIOD: Ranges from 3-8 days but it may be as short as 10 days or as long as year. CLINICAL PICTURE: it manifest in 2 forms : FURIOUS RABIES and DUMB RABIES. FURIOUS RABIES: Typical mad dog syndrome.

33. CHANGE IN BEHAVIOUR - loses its fear of people , aggressive , bites unusual objects stick straw and mud. RUNNING AMUCK : Tendency to run away from home and wander. CHANGE IN VOICE: Barks and growls in a hoarse voice or unable to bark. EXCESSIVE SALIVATION : Foaming at the angle of the mouth. PARALYTIC STAGE : Later stages paralysis of the whole body leading to coma and death.

34. DUMB RABIES: Exciting and irritating stage is lacking. ts predominantly paralytic. Dog withdraws from being seen and disturbed. Dies in about 3 days. LAB DIAGNOSIS: FLUROCENT ANTIBODY TEST : Highly reliable and single test for rabies antigen detection. MICROSCOPIC EXAMINATION : Negri bodies identifies 75% to 90% cases.

35. MOUSE INCCOCULATION TEST : Intracerebral mouse inccoculation of the infected brain tissue shows sign of rabies between 6-8 days if infected. CORNEAL TEST : Antigen detection in the corneal impression or in the frozen skin biopsy by FRA. CONROL MEASURES: IMMUNIZATION OF THE DOGS : Mass vaccination of the dogs. All dogs must receive primary immunization 3,4 months and the booster doses at regular interval. BPL inactivated nervous tissue vaccine : Revaccination done after 6 month and every year subsequently. Modified live virus vaccine : Booster every 3 years.

36. CONTROL OF URBAN RABIES Cost effective approach is either elimination of street dogs and ownerless dogs combined with mass immunization on at least 80% of the area. Registration and licensing of all domestic dogs. Restrain in public places. Immediate destruction of dogs and cats bitten by rabies animal. Quarantine for 6 month of imported dogs. Health education ORAL VACCINE: for immunization of dogs

37. Following an outbreak of JE in Gorakhpur and Basti divisions in eastern Uttar Pradesh during 2005, Directorate of NVBDCP developed surveillance guidelines for endemic states and advised that all the JE cases be reported under Acute Encephalitis Syndrome(AES) as they have common similar clinical manifestations. Their case management usually follows a common protocol along with situation specific treatment. Diagnosis of JE will depend on laboratory investigations. GUIDELINES FOR MANAGEMENT OF AES INCLUDING JAPANESE ENCEPHALITIS IN INDIA (2014)

38. Case definition of suspected case Acute onset of fever, not more than 5-7 days duration Change in mental status with/without New onset of seizures (excluding febrile seizures) Other early clinical findings – may include irritability, somnolence or abnormal behaviour greater than that seen with usual febrile illness.

39. Laboratory-confirmed case A suspected case with any one of the following markers: Presence of IgM antibody in serum and/or CSF to a specific virus including JE/ Enterovirus or others Four fold difference in IgG antibody titre in paired sera Virus isolation from brain tissue Antigen detection by immunofluroscence Nucleic acid detection by PCR Case classification

40. Probable cases Suspected case in close geographic and temporal relationship to a laboratory-confirmed case of AES/JE in an outbreak. Acute Encephalitis Syndrome (AES) due to other agent A suspected case in which diagnostic testing is performed and an etiological agent other than AES/JE is identified. Acute Encephalitis Syndrome (AES) due to unknown agent A suspected case in which no diagnostic testing is performed/no etiological agent is identified/test results are indeterminate.

41. Causes of Acute Encephalitis Syndrome

42. Management of AES including Japanese Encephalitis

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