Standard Operating Procedure for Rabies. November Key facts

Transcription

1 Standard Operating Procedure for Rabies November 2011 Key facts Rabies occurs in more than 150 countries and territories. Dogs are the source of 99% of human rabies deaths. Worldwide, more than people die of rabies every year. 40% of people who are bitten by suspect rabid animals are children under 15 years of age. Wound cleansing and immunization within a few hours after contact with a suspect rabid animal can prevent the onset of rabies and death In Rwanda, an estimation of 127 Human dogs bites was registered in 11 Health Center and Hospital from January to September 2010 (Ministry of agriculture,animal resources)

2 Contents 1. Introduction Transmission Estimated burden of rabies in the world and in rwanda Symptoms Diagnosis Clinical Diagnosis Laboratory diagnosis Treatment After exposure... 7 Local treatment of the wound Prevention Eliminating rabies in dogs Preventive immunization in people Epidemiological surveillance... 9

3 1. Introduction Rabies is a zoonotic disease (a disease that is transmitted to humans from animals) that is caused by a virus (Lyssavirus). The disease infects domestic and wild animals, and is spread to people through close contact with infected saliva via bites or scratches. Rabies is present on all continents with the exception of Antartica, but more than 95% of human deaths occur in Asia and Africa. Once symptoms of the disease develop, rabies is nearly always fatal. 2. Transmission People are infected through the skin following a bite or scratch by an infected animal. Dogs are the main host and transmitter of rabies. They are the source of infection in all of the estimated human rabies deaths annually in Asia and Africa. Bats scratch can also be a source of rabies infection Transmission can also occur when infectious material usually saliva comes into direct contact with human mucosa or fresh skin wounds. 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. 3. Estimated burden of rabies in the world and in Rwanda The highest financial expenditure in any country is the cost of rabies post-exposure prophylaxis. The type of vaccine, vaccine regimen and route of administration as well as the type of immunoglobulin used all significantly influence the cost of treatment. In Rwanda, an estimation of 127 Human bites dogs was registered in 11 Health Center and Hospital from January to September 2010(Ministry of agriculture, animal resources)

4 4. Symptoms The incubation period for rabies is typically 1 3 months, but may vary from <1 week to >1 year. The initial symptoms of rabies are fever and often pain or an unusual or unexplained tingling, pricking or burning sensation (paraesthesia) at the wound site. As the virus (Lyssavirus) spreads through the central nervous system, progressive, fatal inflammation of the brain and spinal cord develops. Two forms of the disease can follow. People with furious rabies exhibit signs of hyperactivity, excited behaviour, hydrophobia and sometimes aerophobia. After a few days, death occurs by cardio-respiratory arrest. Paralytic rabies accounts for about 30% of the total number of human cases. This form of rabies runs a less dramatic and usually longer course than the furious form. The muscles gradually become paralyzed, starting at the site of the bite or scratch. A coma slowly develops, and eventually death occurs. The paralytic form of rabies is often misdiagnosed, contributing to the underreporting of the disease. 5. Diagnosis 5.1. Clinical Diagnosis No tests are available to diagnose rabies infection in humans before the onset of clinical disease, and unless the rabies-specific signs of hydrophobia or aerophobia are present, the clinical diagnosis may be difficult. After the first exposure (in most people, an animal bite), the symptoms of itching or discomfort like pins or needles pricking the skin occur at the bite area. In addition, the person may develop fever and a headache. Investigators suggest these symptoms may last from about two days to weeks. This is the acute phase or the acute incubation phase of the disease. Unfortunately, there is another incubation period before the next set of signs and symptoms develop.

5 The symptoms and signs of rabies in humans may consist of some or many of the following: Anxiety, stress, and tension,delirium,drooling,convulsions,exaggerated sensation at the bite site, excitability or combative, hallucinations, loss of feeling in an area of the body, loss of muscle function, low-grade fever, muscle spasms, numbness and tingling, pain at the site of the biter, restlessness, insomnia, swallowing difficulty (drinking causes throat spasms and the person may become hydrophobic) Post mortem, the standard diagnostic technique is to detect rabies virus antigen in brain tissue by fluorescent antibody test Laboratory diagnosis Laboratory Diagnosis Definite diagnosis of rabies can only be obtained by laboratory investigations. Biosafety considerations Rabies has the highest case-fatality rate of any currently recognized infectious disease. Safety is of paramount importance when working with lyssaviruses. In general, biosafety level 2 safety practices are adequate for routine laboratory activities such as diagnosis and animal handling. Besides basic facility design, precautions should also include personal protection equipment (e.g. clothing) and pre-exposure vaccination. Certain situations may entail consideration of a biosafety level 3 classification, including production of large quantities of concentrated virus, conducting procedures that may generate aerosols and when working with lyssaviruses for which the effectiveness of current prophylaxis is not known. All national safety guidelines for working with infectious agents should be followed. Transport of specimens Specimens for rabies diagnosis should be shipped according to the national and international regulations to avoid exposure hazards. Information on classification (UN 2814) and packing instructions (P620 packaging) can be found in Transport of infectious substances (15). Diagnostic specimens should either be refrigerated

6 or shipped at room temperature in 50% glycerine-saline solution. Source of specimens for diagnosis and storage conditions Rabies diagnosis can be performed on fresh specimens from several different tissue sources or on appropriate specimens stored at proper temperatures, preferably refrigerated. The choice of specimens depends on the test to be performed and the stage of the disease in humans. Formalin fixation of brain tissues is not recommended. If specimens are nevertheless received in formalin, the duration of fixation should be less than 7 days. The specimens should be transferred rapidly to absolute ethanol for subsequent molecular diagnosis. Sampling for intra vitam diagnosis Secretions and biological fluids (saliva, spinal fluid, tears, etc.) and tissues can be used to diagnose rabies during life (intra vitam). They should be stored at 20 C or below. Serum should be collected from blood samples prior to freezing and stored at 20 C or below. Sampling for postmortem diagnosis Brain tissue is the preferred specimen for postmortem diagnosis in both humans and animals. In cases where brain tissue is not available, other tissues may be of diagnostic value. In field studies or when an autopsy cannot be performed, techniques of collecting brain-tissue samples via trans-orbital or trans-foramen magnum route can be used (16, 17). The use of glycerine preservation (temperature: +4 C or 20 C) or dried smears of brain tissue on filter paper(temperature: +30 C) also enables safe transportation of infected material.

7 6. Treatment 6.1. After exposure Effective treatment soon (within a few days, but as soon as possible) after exposure to rabies can prevent the onset of symptoms and death. Post-exposure prevention consists of local treatment of the wound, administration of rabies immunoglobulin (if indicated), and immediate vaccination. Local treatment of the wound Removing the rabies virus at the site of the infection by chemical or physical means is an effective means of protection. Therefore, prompt local treatment of all bite wounds and scratches that may be contaminated with rabies virus is important. Recommended first-aid procedures include immediate and thorough flushing and washing of the wound for a minimum of 15 minutes with soap and water, detergent, povidone iodine or other substances that kill the rabies virus. N.B: Stitching of the wound is contraindicated Patient with Confirmed cases of rabies should be isolated, sedated and transferred appropriate medical facility (referral hospital), preferably in a private room with suitable emotional and physical support because of the perceived risk of transmission of the virus through contact. Once rabies diagnosis has been confirmed, invasive procedures should be avoided. N.B: Treatment should centre on comfort care; using heavy sedation (barbiturates, morphine) and avoidance of intubation and life-support measures once the diagnosis is certain.

8 Recommended treatment The recommended post-exposure prophylaxis depends on the type of contact with the suspected rabid animal (see table). Table: Recommended post-exposure prophylaxis for rabies infection Category of exposure to suspect rabid animal Category I touching or feeding animals, licks on intact skin (i.e. no exposure) Category II nibbling of uncovered skin, minor scratches or abrasions without bleeding Category III single or multiple transdermal bites or scratches, licks on broken skin; contamination of mucous membrane with saliva from licks, exposures to bats. Post-exposure measures None Immediate vaccination and local treatment of the wound Immediate vaccination and administration of rabies immunoglobulin; local treatment of the wound N.B: The health officer (Doctor, Nurse, ) should contact immediately the nearest veterinary for dog isolation and follow up. Other factors that should be taken into consideration when deciding whether to initiate postexposure prevention include: the likelihood of the implicated animal being rabid the clinical features of the animal and its availability for observation and laboratory testing. In developing countries, the vaccination status of the suspected animal alone should not be considered when deciding whether to initiate prophylaxis or not.

9 7. Prevention 7.1. Eliminating rabies in dogs Rabies is a vaccine-preventable disease. The most cost-effective strategy for preventing rabies in people is by eliminating rabies in dogs through vaccination. Vaccination of animals (mostly dogs) has reduced the number of human (and animal) rabies cases in several countries, particularly in Latin America. However, recent increases in human rabies deaths in parts of Africa, Asia and Latin America suggest that rabies is re-emerging as a serious public health issue. Preventing human rabies through control of domestic dog rabies is a realistic goal for large parts of Africa and Asia, and is justified financially by the future savings of discontinuing postexposure prophylaxis for people Preventive immunization in people Safe, effective vaccines also exist for human use. Pre-exposure immunization in people is recommended for travellers to high-risk areas in rabies-affected countries, and for people in certain high-risk occupations such as laboratory workers dealing with live rabies virus and other lyssaviruses, and veterinarians and animal handlers in rabies-affected areas. As children are at particular risk, their immunization could be considered if living in or visiting high risk areas Epidemiological surveillance Dogs bites must be notifiable within national surveillance system on weekly basis. Epidemiological data should be collected, processed, analysed and disseminated rapidly between sectors and different administrative levels. Steps supposed to be taken after reporting dog b ite: Dog movement: Is it a stray or restricted dog? Circumstances around the bite: Is the dog provoked or not? Dog vaccination status The offending dog should be contained and observed for 14 days

10 Key message: Rabies Prevention 1. Visit your veterinarian with your dog or cat on a regular basis and keep rabies vaccinations up-to-date for all dogs and cats. 2. Maintain control of your dog or cat by keeping them indoors and keeping dogs under direct supervision. 3. Call animal control/police or local leader to remove all stray animals (dogs and cats) from your neighborhood since these animals may be unvaccinated or ill. 4. Wash the wound with soap immediately after a dog bites 5. Immediate consultation at the nearest hospital for medical care 6. Inform the nearest veterinarian for dog isolation