Rabies PDF

RABIES Prof. Ameer kadhim Hussein M.B.Ch.B. FICMS (Community Medicine)  OBJECTIVES Describe and discuss the epidemiology and mode of transmission of Rabies. Describe and discuss preventive and control measures including (pre- exposure and post exposure prophylaxis) of Ra...

RABIES Prof. Ameer kadhim Hussein M.B.Ch.B. FICMS (Community Medicine)  OBJECTIVES Describe and discuss the epidemiology and mode of transmission of Rabies. Describe and discuss preventive and control measures including (pre- exposure and post exposure prophylaxis) of Rabies  DEFINITION Rabies is an acute highly fatal viral disease of central nervous system caused by Lyssa virus type 1. It is zoonotic disease of warm blooded animals especially carnivorous animals such as dogs, cats and wolves. It is transmitted to man usually by bites or licks of rabid animals.  INTRODUCTION Rabies is a viral zoonotic disease that causes progressive and fatal inflammation of the brain and spinal cord. Clinically, it has two forms: 1. Furious rabies – characterized by hyperactivity and hallucinations. 2. Paralytic rabies – characterized by paralysis and coma. Although fatal once clinical signs appear, rabies is entirely avoidable; vaccines, medicines and technologies have long been available to prevent death from rabies. Nevertheless, rabies still kills tens of thousands of people each year. Of these cases, approximately 99% are acquired from the bite of an infected dog.  INTRODUCTION Dog-mediated human rabies can be eliminated by tackling the disease at its source: infected dogs. Making people aware of how to avoid the bites of rabid dogs, to seek treatment when bitten and to vaccinate animals can successfully disrupt the rabies transmission cycle. Rabies is estimated to cause 59 000 human deaths annually in over 150 countries, with 95% of cases occurring in Africa and Asia. Due to underreporting and uncertain estimates, this number is likely a gross underestimate. Approximately half of cases attributable to children under 15 years of age.  GEOGRAPHICAL DISTRIBUTION Rabies is an enzootic and epizootic disease of world wide importance. Some countries have achieved (rabies free) by vigorous campaign of elimination while in others the disease has never been introduced. Water is regard as the most important barrier for rabies. Rabies free area is defined as area in which no case of indigenously acquired rabies has been reported in man or animal in previous 2 years in presence of surveillance system and health regulations.  GLOBAL DISTRIBUTION OF HIGH-RISK LOCATIONS FOR HUMAN RABIES (WHO, 2018) Infectious agent: Lyssa virus type1 which is RNA virus belong to rhabdoviridae family. Reservoir of infection: Wild and domestic animal including dogs, foxes, wolves and other biting animals. Bats also regard as a reservoir of infection in some area like Mexico. 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 to 4 days before the onset of disease and persist during the course of illness until death. THE SOURCE OF INFECTION TO MAN IS THE SALIVA OF RABID ANIMALS Susceptibility: All mammals are susceptible. Studies show that not every person bite by rabid animal and not receive treatment develop disease but those develop disease represent about 40%. Mode of transmission: 1. Animal bites. 2. Licks on abraded skin and mucosa. 3. Aerosols: in caves harboring rabies infected bats. 4. Person to person: man to man transmission although rare but possible by corneal and organ transplants. Incubation period: The incubation period in man is highly variable commonly 3 to 8 weeks (sometimes as short as 4 days and may persist to many years). The incubation period depend on the following: 1. Site of bite. 2. Severity of bite. 3. Number of the wounds. 4. Amount of virus injected. 5. Species of the biting animal. 6. Protection provided by clothes and treatment. Shorter incubation period occur in: (Sever exposure, bite in head, neck, face and upper extremities and bite by wild animal).  CLINICAL PICTURE AND DIAGNOSIS Clinical picture: The disease begins with prodromal symptoms such as headache, malaise, sore throat and slight fever for 3-4 days. This stage is followed by widespread excitation of nervous system. The patient is intolerant to noise, bright light with aerophobia and hydrophobia which pathognomonic of rabies. Duration of disease is 2 to 3 days the patient may be die abruptly during convulsions or may pass to paralysis or coma. Diagnosis: Rabies can be confirmed in patients by antigen detection using immunofluorescence of skin biopsy and by virus isolation from saliva and other secretions.  METHODS OF CONTROL A.PREVENTIVE MEASURES 1. Immunize all dogs and cats in enzootic countries. 2. Maintain active surveillance for rabies in animals. 3.Observe clinically for 10 days any dog or cat known to have bitten person (unwanted dog or cat can be sacrificed immediately and examine for rabies) if the biting animal was infected at time of bite, sign of rabies will usually occur within 4-7 days with paralysis followed by death. The head of animal must be send to laboratory to confirm diagnosis of rabies by microscopically identification of Negri bodies. 4. Individuals who are at high risk for rabies should be protected by pre exposure immunization using potent and safe cell culture vaccine which given in 3 doses of (1ml) IM on days (0,7,21 or 28). If the risk of exposure continue booster doses need to be given at interval of 2 years. Those individuals include the following: a. Laboratory staff working with rabies virus. b. Veterinarians. c. Animal handlers. d. Wild life officers. e. Long term travelers to rabies endemic area. 5. Post exposure prophylaxis: Which is usually done for prevention of rabies after animal bites. Post exposure prophylaxis include the following: a. First aid: Immediate washing the wound with plenty of soap and water under a running tap with at least 15 minutes. b. Chemical treatment: using virucidal agents including alcohol or 0.01% aqueous solution of iodine or povidone iodine. c. Suturing: Bite wounds should be not sutured immediately to prevent additional trauma which may lead to spread the virus to deeper tissues , if suturing is necessary it should be done 24 to 48 hours later with minimum possible stitches under cover of anti rabies serum. Wound cleaning & treatment d. Anti rabies serum: local application of anti rabies serum is very effective in preventing rabies. e. Antibiotics and anti tetanus measures. f. Observe the animal for 10 days: if the animal show sign of rabies it should be killed and the head send to laboratory examination to ensure the diagnosis. If the animal remain alive and healthy at the end of 10 days there is no indication of anti rabies treatment. g. Vaccine administration: By using modern cell culture vaccine with routine intra muscular schedule in deltoid muscle which consist of 6 doses of (1 ml) on days (0, 3, 7, 14 , 28 and 90). VACCINE ADMINISTRATION Indications of anti rabies treatment: a. If the animal show sign of rabies or die within 10 days of observation. b. If the biting animal cannot be identified. c. All bites by wild animals. d. If laboratory tests of brain of animal is positive for rabies. e. Unprovoked bites. 6.Post exposure prophylaxis of person who have been vaccinated previously If the patient antibody titre is unknown or the bite is severe we use (3 IM doses of vaccine on days 0, 3 and 7) while if titre is high or bite is not so severe so give (2 doses on days 0 and 3). No need for systemic passive immunization (IG).  Exposure Type of contact with Treatment category suspected rabid animal touching or feeding animals, licks category I on intact skin None Administer vaccine immediately , stop treatment if nibbling of uncovered skin, minor animal remain healthy category II scratches or abrasions without throughout 10 days of bleeding, licks on broken skin observation or laboratory test negative for rabies Administer vaccine and immunoglobulin immediately , single or multiple transdermal stop treatment if animal remain bites or scratches, contamination healthy throughout 10 days of category III of mucous membrane with saliva observation or laboratory test from licks negative for rabies RABIES VACCINE B. CONTROL OF PATIENT, CONTACTS AND IMMEDIATE ENVIRONMENT 1. Report to local health authority. 2. Concurrent disinfection: of saliva and articles soiled with them. 3. Immunization of contacts: contacts who have open wound or mucus membrane expose to patient saliva should receive anti rabies treatment. 4. Investigation of contacts and source of infection by searching for rabid animals. 6. Specific treatment: only by supportive medical care.  CASE SCENARIO 49 years old male exposed to dog bite on his left knee since one hour and dog run away, the patient was hypertensive and diabetic. The patient visited the emergency department and he was aware and alert. Vital signs (HR= 80 BPM, RR=13 BPM, Blood pressure was 150/90, temperature 37.5 degree Celsius. Doctor in emergency unit treat him as follows (post-exposure prophylaxis) A. Immediate washing the wound with plenty of soap and water under a running tap for15 minutes. b. Povidone iodine for the wound. C. Anti rabies serum: 20 IU/Kg body weight.  CASE SCENARIO D. Antibiotics and anti tetanus measures. g. Vaccine administration: Using modern cell culture vaccine intra muscular injection in deltoid muscle of dose (1 ml) which considered as day 0 and inform the patient about need to continue on vaccine for other 5 doses on days (3, 7, 14 , 28 and 90).  SUMMARY  Rabies is a vaccine-preventable viral disease which occurs in more than 150 countries and territories.  Dogs are the source of the vast majority of human rabies deaths and Rabies elimination is feasible by vaccinating dogs.  Infection causes tens of thousands of deaths every year, mostly in Asia and Africa.  40% of people who are bitten by suspect rabid animals are children under 15 years of age.  After a potential exposure of people to a rabid animal, they can seek post-exposure prophylaxis (PEP), which consists of immediate, thorough wound washing with soap and water for 15 minutes, a series of rabies vaccinations and, if indicated, administration of rabies immunoglobulin or monoclonal antibodies, which can be life-saving..  Every year, more than 29 million people worldwide receive a post-bite vaccination. This is estimated to prevent hundreds of thousands of rabies deaths annually.  SUMMARY  Rabies, a zoonotic disease, requires close co-ordination between animal and human health sectors at the national, regional and continental levels. In December 2015, a global framework to reach zero human rabies deaths by 2030 was launched by WHO and the World Organization for Animal Health (OIE), in collaboration with the Food and Agriculture Organization of United Nations (FAO) and the Global Alliance for Rabies Control. This initiative marks the first time that the human and animal health sectors have come together to adopt a common strategy against this devastating but massively neglected disease.  SUMMARY  Globally rabies causes an estimated cost of US$ 8.6 billion per year  WHO leads the collective “United Against Rabies” to drive progress towards "Zero human deaths from dog- mediated rabies by 2030".  Bangladesh launched an elimination programme in 2010 and, through the management of dog bites, mass dog vaccination and increased availability of vaccines free of charge, human rabies deaths decreased by 50% during 2010–2013. WORLD'S RABIES DAY (ON SEPTEMBER 28) World Rabies Day is celebrated annually to raise awareness about rabies prevention and to highlight progress in defeating this horrifying disease. 28 September also marks the anniversary of Louis Pasteur's death, the French chemist and microbiologist, who developed the first rabies vaccine. GLOBAL PARTNERS ANNOUNCE PLAN TO END HUMAN DEATHS FROM DOG-TRANSMITTED RABIES BY 2030  REFERENCES 1.Park text book of preventive and social medicine. 27th edition (2023). 2.World health organization,2024. https://www.who.int/news-room/fact- sheets/detail/rabies 3.Control of Communicable Diseases Manual, 21th Edition,2022.