Tuesday, September 1, 2009
Post-exposure treatment of previously vaccinated persons
source:WHO
Administration of rabies immunoglobulin
Rabies immunoglobulin of human origin (HRIG) is available in some countries; however, it is expensive and only limited amounts are available.
Rabies immunoglobulin of equine origin (ERIG) is available in many countries and is considerably cheaper than HRIG. Most of the currently available preparations of ERIG are highly purified and quite safe; however, a skin test should always be carried out prior to its use.
source: WHO
Preventing rabies with the Verorab vaccine: 1985-2005 Twenty years of clinical experience.
Burggartenstrasse 32, 4103 Bottmingen, Switzerland. malaria@freesurf.ch
Purified rabies vaccine cultured on Vero cells (Verorab, sanofi pasteur) is WHO-approved for pre- and post-exposure prophylaxis by intradermal and intramuscular routes. During 20 years of use, over 40 million doses of Verorab have been administered in more than 100 countries. No serious adverse event due to Verorab has been reported in clinical trials involving 3937 persons, and Verorab is better tolerated than human diploid cell vaccine (HDCV). Pre-exposure prophylaxis is confirmed immunogenic in 1437 subjects by all routes, with prompt responses following boosting; Verorab boosts effectively subjects pre-immunized with HDCV. Unlike HDCV, Verorab is not associated with post-boosting serum sickness. In the absence of data in immunodeficient/HIV-positive individuals, pre-exposure immunization is urged as early as possible. Essen, Zagreb, Thai Red Cross Intradermal (TRC-ID) and other post-exposure intramuscular and intradermal regimens are documented. Two thousand one hundred and eighty-three subjects received post-exposure prophylaxis, including 874 high risk, severe or confirmed rabid attacks. Co-administration of rabies immune globulin (RIG) does not affect neutralizing antibody levels when Essen or TRC-ID regimens are employed; levels are lower with the Zagreb regimen. Verorab has been administered safely and effectively post-exposure to 251 pregnant women, without any increase in congenital malformations or spontaneous abortions. From a pediatric perspective, safety and efficacy have been demonstrated in 759 children (0-15 years). Intradermal post-exposure Verorab is an effective and inexpensive option for developing countries. Inadvertent subcutaneous administration does not reduce immunogenicity. WHO already strongly recommends the replacement of nerve tissue vaccines with modern vaccines. Extensive clinical experience supports the use of Verorab for intramuscular and intradermal pre- and post-exposure prophylaxis, including in special situations.
Source: PMID: 17983973 [PubMed - indexed for MEDLINE]
Monday, August 31, 2009
Rabies Vaccine
French scientist Louis Pasteur developed the first vaccine against rabies. In 1885, he injected his attenuated (weakened) virus into a nine-year-old boy who had been bitten by a rabid dog. The child's life was saved. Over the following century several generations of rabies vaccines were developed. In the 1980s scientists developed a highly effective vaccine that provides protection from the virus both before exposure—pre-exposure prophylaxis—or after exposure—post-exposure prophylaxis. The vaccine consists of killed rabies virus that, when injected, induces the child's immune system to produce antibodies that bind to and destroy the virus. The antibody response develops within seven to 10 days of vaccination and provides protection for up to two years. A second type of rabies vaccine, rabies immune globulin (RIG), provides immediate, short-term protection after exposure to the virus.
Different Class of Rabies Vaccine:
Nerve Tissue Vaccine
Avian Embryo Vaccine
Cell Culture Vaccine
The tissue culture vaccines available in India .
# HUMAN DIPLOID CELL VACCINE (HDCV)
Human diploid cell vaccines (HDCVs) use inactivated rabies viruses. HDCV comes in two formulations: one for intramuscular (IM) injection and one for intradermal (ID) injection into a deep layer of skin. HDCV are based on Pitman-Moore L503 strain or in one case Flury strain of Rabies virus.
# PURIFIED CHICK EMBRYO CELL VACCINE (PCEC)
Purified chick embryo cell (PCEC) vaccine is made from rabies virus grown in cultures of chicken embryos and then inactivated. The drug is formulated for IM administration only.The PCEC is prepared from inactivated rabies virus of the Flury LEP-25 strain.
# Verocell Vaccine:
The purified verocell rabies vaccine contains the Winstar strain of the virus, but with vero cell line as substrate
RABIES IMMUNE GLOBULIN (RIG) Human rabies immune globulin (RIG, HRIG) is a vaccine made from human serum that contains high levels of antibodies against rabies. It is used in conjunction with an inactivated-rabies vaccine for post-exposure prophylaxis. RIG provides immediate but short-lived protection against rabies. Approximately one-half of the antibodies are lost within 21 days after administration. RIG is separated from the blood plasma of hyperimmunized human donors. Numerous procedures are used to clear the serum of rabies virus.
Source:Wikipedia,Essentialdrug.org
RABIES - SYMPTOMS,PREVENTION
Symptoms of Rabies
Symptoms usually develop between 20 and 60 days after exposure. Rabid animals may become aggressive, combative, and highly sensitive to touch and other kinds of stimulation. And they can be vicious. This is the "furious" form of rabies, the kind traditionally associated with mad dogs. There is also a "dumb" form of the disease in which the animal is lethargic, weak in one or more limbs, and unable to raise its head or make sounds because its throat and neck muscles are paralyzed. In both kinds of animal rabies, death occurs a few days after symptoms appear, usually from respiratory failure.
In humans, the course is similar. After a symptom-free incubation period that ranges from 10 days to a year or longer (the average is 30 to 50 days), the patient complains of malaise, loss of appetite, fatigue, headache, and fever. Over half of all patients have pain (sometimes itching) or numbness at the site of exposure. They may complain of insomnia or depression. Two to 10 days later, signs of nervous system damage appear, hyperactivity and hypersensitivity, disorientation, hallucinations, seizures, and paralysis. Death may be sudden, due to cardiac or respiratory arrest, or follow a period of coma that can last for months with the aid of life-support measures.
The advent of scientific medicine makes rabies control possible, not by cure but by prevention. Unlike other immunizations, the rabies vaccine is administered after exposure to the virus. This unusual technique is successful because the rabies virus takes a comparatively long time to induce disease, a minimum of 10 days, and in rare cases, up to a year. The length of the incubation period apparently depends on both the location of the wound - the farther from the brain, the longer the incubation - and the dose of virus received. No matter where the wound, authorities emphasize that the first and most valuable preventive measure is thorough cleaning of the site with soap and water, and immediate medical attention. If rabies vaccine treatment is called for, it should be started as soon as possible after exposure. Counting the first day of vaccine treatment as day 0, injections are administered on days 0, 3, 7, 14, and 28. In addition to vaccine, patients who have not previously been vaccinated for rabies also receive an injection of rabies immune globulin (RIG) on the day they get the first vaccine (day 0). RIG is prepared from the blood of persons who have been immunized against rabies and contains antibodies to the rabies virus. This "passive" immunity helps protect patients during the period before the rabies vaccine causes their own immune system to counter the virus (active immunity).
source:wikipidea,google
Treatment after exposure
Wound cleansing and immunizations, done as soon as possible after suspect contact with an animal and following WHO recommendations, can prevent the onset of rabies in virtually 100% of exposures.
Recommended treatment to prevent rabies depends on the category of the contact:
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
Post-exposure care to prevent rabies includes cleaning and disinfecting a wound, or point of contact, and then administering anti-rabies immunizations as soon as possible. Anti-rabies vaccine is given for Category II and III exposures. Anti-rabies immunoglobin, or antibody, should be given for Category III contact, or to people with weaker immune systems. When humans are exposed to suspect animals, attempts to identify, capture or humanely sacrifice the animal involved should be undertaken immediately. Post-exposure treatment should start right away and only be stopped if the animal is a dog or cat and remains healthy after 10 days. Animals that are sacrificed or have died should be tested for the virus, with results sent to responsible veterinary services and public health officials so that the situation in the area is well documented.
source : wikipedia,google
FAQ SERIES 1
Q: How do people get rabies?
A: People usually get rabies from the bite of a rabid animal. It is also possible, but quite rare, that people may get rabies if infectious material from a rabid animal, such as saliva, gets directly into their eyes, nose, mouth, or a wound.
Q: Can I get rabies in any way other than an animal bite?
A: Non-bite exposures to rabies are very rare. Scratches, abrasions, open wounds, or mucous membranes contaminated with saliva or other potentially infectious material (such as brain tissue) from a rabid animal constitute non-bite exposures. Occasionally reports of non-bite exposure are such that postexposure prophylaxis is given. Inhalation of aerosolized rabies virus is also a potential non-bite route of exposure, but other than laboratory workers, most people are unlikely to encounter an aerosol of rabies virus. Other contact, such as petting a rabid animal or contact with the blood, urine or feces (e.g., guano) of a rabid animal, does not constitute an exposure and is not an indication for prophylaxis.
Q: How soon after an exposure should I seek medical attention?
A: Medical assistance should be obtained as soon as possible after an exposure.
Q: What medical attention do I need if I am exposed to rabies?
A: One of the most effective methods to decrease the chances for infection involves thorough washing of the wound with soap and water. Specific medical attention for someone exposed to rabies is called postexposure prophylaxis or PEP. In the United States, postexposure prophylaxis consists of a regimen of one dose of immune globulin and five doses of rabies vaccine over a 28-day period. Rabies immune globulin and the first dose of rabies vaccine should be given by your health care provider as soon as possible after exposure. Additional doses or rabies vaccine should be given on days 3, 7, 14, and 28 after the first vaccination. Current vaccines are relatively painless and are given in your arm, like a flu or tetanus vaccine
Q: Will the rabies vaccine make me sick?
A: Adverse reactions to rabies vaccine and immune globulin are not common. Newer vaccines in use today cause fewer adverse reactions than previously available vaccines. Mild, local reactions to the rabies vaccine, such as pain, redness, swelling, or itching at the injection site, have been reported. Rarely, symptoms such as headache, nausea, abdominal pain, muscle aches, and dizziness have been reported. Local pain and low-grade fever may follow injection of rabies immune globulin.
Q: Can rabies be transmitted from one person to another?
A: The only well-documented documented cases of rabies caused by human-to-human transmission occurred among 8 recipients of transplanted corneas, and recently among three recipients of solid organs (see MMWR article). Guidelines for acceptance of suitable cornea and organ donations, as well as the rarity of human rabies in the United States, reduce this risk. In addition to transmission from cornea and organ transplants, bite and non-bite exposures inflicted by infected humans could theoretically transmit rabies, but no such cases have been documented. Casual contact, such as touching a person with rabies or contact with non-infectious fluid or tissue (urine, blood, feces) does not constitute an exposure and does not require postexposure prophylaxis. In addition, contact with someone who is receiving rabies vaccination does not constitute rabies exposure and does not require postexposure prophylaxis.
Q: What happens if my pet (cat, dog, ferret) is bitten by a wild animal?
A: Any animal bitten or scratched by either a wild, carnivorous mammal or a bat that is not available for testing should be regarded as having been exposed to rabies. Unvaccinated dogs, cats, and ferrets exposed to a rabid animal should be euthanized immediately. If the owner is unwilling to have this done, the animal should be placed in strict isolation for 6 months and vaccinated 1 month before being released. Animals with expired vaccinations need to be evaluated on a case-by-case basis. Dogs and cats that are currently vaccinated are kept under observation for 45 days.
Q: What animals get rabies?
A: Any mammal can get rabies. The most common wild reservoirs of rabies are raccoons, skunks, bats, foxes, and coyotes. Domestic mammals can also get rabies. Cats, cattle, and dogs are the most frequently reported rabid domestic animals in the United States.
Sunday, August 30, 2009
The Rabies Virus
negative-stranded RNA genomes. Rhabdoviruses are approximately 180 nm long and 75 nm wide. The rabies genome encodes five proteins: nucleoprotein (N), phosphoprotein (P), matrix protein (M), glycoprotein (G) and polymerase (L).
Replication:
The fusion of the rabies virus envelope to the host cell membrane (adsorption) initiates the infection process. After adsorption, the virus penetrates the host cell and enters the cytoplasm by pinocytosis (via clathrin-coated pits). The virions aggregate in the large endosomes (cytoplasmic vesicles). The viral membranes fuse to the endosomal membranes, causing the release of viral RNP into the cytoplasm (uncoating). Because lyssaviruses have a linear single-negative-stranded ribonucleic acid (RNA) genome, messenger RNAs (mRNAs) must be transcribed to permit virus replication. The first step in viral replication is synthesis of full-length copies (postive strands) of the viral genome. When the switch to replication occurs, RNA transcription becomes "non-stop" and stop codons are ignored
Transmission:
Transmission of rabies virus usually begins when infected saliva of a host is passed to an uninfected animal. Various routes of transmission have been documented and include contamination of mucous membranes (i.e., eyes, nose, mouth), aerosol transmission, and corneal transplantations. The most common mode of rabies virus transmission is through the bite and virus-containing saliva of an infected host.
Following primary infection, the virus enters an eclipse phase in which it cannot be easily detected within the host. This phase may last for several days or months. Investigations have shown both direct entry of virus into peripheral nerves at the site of infection and indirect entry after viral replication in nonnervous tissue (i.e., muscle cells). During the eclipse phase, the host immune defenses may confer cell-mediated immunity against viral infection because rabies virus is a good antigen. The uptake of virus into peripheral nerves is important for progressive infection to occur.
After uptake into peripheral nerves, rabies virus is transported to the central nervous system (CNS) via retrograde axoplasmic flow. Typically this occurs via sensory and motor nerves at the initial site of infection. The incubation period (see figure, number 4) is the time from exposure to onset of clinical signs of disease. The incubation period may vary from a few days to several years, but is typically 1 to 3 months. Dissemination of virus within the CNS is rapid, and includes early involvement of limbic system neurons. Active cerebral infection is followed by passive centrifugal spread of virus to peripheral nerves. The amplification of infection within the CNS occurs through cycles of viral replication and cell-to-cell transfer of progeny virus. Centrifugal spread of virus may lead to the invasion of highly innervated sites of various tissues, including the salivary glands. During this period of cerebral infection, the classic behavioral changes associated with rabies develop.
Content Source: National Center for Zoonotic, Vector-Borne, & Enteric Diseases (ZVED), http://www.cdc.gov/
What is Rabies
Rabies is a preventable viral disease of mammals most often transmitted through the bite of a rabid animal.Rabies is one of the oldest recognized diseases affecting humans . It has been recognized in India since the Vedic period (1500–500 BC) and is described in the ancient Indian scripture Atharvaveda, wherein Yama, the mythical God of Death, has been depicted as attended by 2 dogs as his constant companions, the emissaries of death.Wild animals like raccoons, skunks, bats, and foxes acts as carrier of Rabies virus. Wihle domestic animals like dog has been, and still is, the main reservoir of rabies in India besides others like cats, cattle,rodents etc.
Rabies virus infects the central nervous system, causing encephalopathy and ultimately death. Early symptoms of rabies in humans are nonspecific, consisting of fever, headache, and general malaise. As the disease progresses, neurological symptoms appear and may include insomnia, anxiety, confusion, slight or partial paralysis, excitation, hallucinations, agitation, hypersalivation, difficulty swallowing, and hydrophobia (fear of water). Death usually occurs within days of the onset of symptoms.
Source: Wiki,WHO Website
About Rabies-Some Key Facts
Most human deaths follow a bite from an infected dog. Between 30% to 60% of the victims of dog bites are children under the age of 15.
Wound cleansing and immunizations, done as soon as possible after suspect contact with an animal and following WHO recommendations, can prevent the onset of rabies in virtually 100% of exposures.
Once the signs and symptoms of rabies start to appear, there is no treatment and the disease is almost always fatal.
Globally, the most cost-effective strategy for preventing rabies in people is by eliminating rabies in dogs through animal vaccinations