Dog Bite and Rabies

Rabies is one of the major public health problems in four WHO regions – AFRO, EMRO, SEARO and WPRO. It is estimated that each year 50,000-55,000 people die of rabies worldwide, 95% of them in Asia. Children in the 5-15 age-groups represent 40% of the people exposed to dog bites (principal animal vector) in the rabies endemic areas. The majority of the bites that occur in children go unreported, leading to lack of timely post-exposure treatment. Thus it is likely that a disproportionately high number of children die of rabies undiagnosed and unrecorded. Rabies is a 100% fatal and 100% preventable disease. However, due to inevitability of death once the disease sets in, most victims die at home rather than the hospital. This accounts for the general lack of surveillance data, under-reporting, lack of awareness among policy makers and as a result, the low priority allocated to this disease and grossly inadequate resources. Consequently, the tag of ‘neglected disease’ perfectly fits rabies.

The rabies virus is bullet shaped with a single stranded RNA genome. Bat Lyssavirus is closely related to classical human rabies virus in many parts of the world.

After a bite, millions of virus particles enter the tissues through the broken skin or mucous membrane. Within a few days to weeks the virus particles enter nerve endings in the muscle and surrounding tissues and travel along the long peripheral nerves toward the brain. Once they reach the brain tissue, symptoms begin and the disease becomes irreversible and invariably fatal.

Human mortality from endemic canine rabies is estimated by WHO to be around 55,000 deaths annually. The estimated annual death toll for Asia is over 31,000. Most deaths occur in underdeveloped countries where population is dense and the number of stray and feral dogs is high. India reports the highest incidence in the world with one bite occurring every 2 seconds and one death from rabies every half hour, adding up to over 17 million bites and 20,000 deaths a year. Thailand, Sri Lanka and Phillipines have controlled rabies reasonably well, reporting only a few deaths per year through mass awareness, because of which dog bite victims seek early and proper medical care.

There are no reliable data from Pakistan but the number of annual rabies deaths here is estimated to be between 2000-5000. Rabies remains a major public health problem in many countries in Asia, South and Central America, Africa, and some Pacific Islands, where unvaccinated dogs roam freely. The highest risk countries for travelers include Colombia, Ecuador, El Salvador, Guatemala, India, Mexico, Nepal, Philippines, Sri Lanka, Thailand, and Viet Nam. Most human rabies in the Americas and Europe are due to bites by rabid wild animals, including bats. Most rabies cases in the USA and Canada are of bat origin. Australia has never reported human rabies. Children under 15 years age are most affected as they usually play in the streets and are unable to run away or defend themselves against an attacking animal.

Only four rabies survivors have been reported in literature, all related to bat bite and presenting with atypical rabies. A few other anecdotal cases have been reported but not substantiated with lab tests.

Rabies is primarily a disease of animals (zoonotic disease) and is transmitted to man by the bite or scratch of an infected animal. Many mammals can transmit the rabies virus, but in Pakistan it is usually spread through infected dogs; however cats have occasionally been reported to transmit the disease as well. Saliva from the infected dog can contaminate the paws, and hence a scratch is capable of transmitting the virus. A rabid dog may have bitten other animals such as another dog, cat, mule or cattle which can become rabid as well. Thus the infection is transmitted from animal to animal and the disease is perpetuated. The infected animal demonstrates signs of rabies and dies due to the infection within 5-10 days of showing signs of illness.

The initial manifestation of encephalitis may be confused with other viral encephalitides, illicit drug overdose, and hysterics. The subsequent syndrome is unmistakable and should present no other differential.

Symptoms develop within 2 weeks to 6 months or even longer after a bite. The length of the incubation period depends upon the body site where the bite has occurred, and the number of virus particles entering into the wound. For instance, a bite on the head, neck, shoulders or arms will produce symptoms earlier than if the bite occurred on the leg or feet.

Classical rabies presents with feverishness, headache, and periods of mental confusion alternating with periods of normal mentation. These symptoms are unique to rabies. Patients with Japanese encephalitis, herpes and other viral encephalitides do not have alternating symptoms. These are signs of viral encephalitis. This is followed by involvement of the muscles of swallowing and breathing, so that the victim has difficulty in swallowing water and actually begins to fear even a glass of water. This is called “hydrophobia”. (This symptom is responsible for the myth that drinking water or washing the wound with water is harmful for the victim!) Blowing air on the face also causes spasms, provoking fear of breeze, called “aerophobia”. There is intense sweating, tachycardia and acute hypertension as a result of autonomic dysfunction. Over 1 to 7 days the condition worsens, swallowing and breathing become difficult, the number of spasms increase and slow, painful death occurs while the doctors and family members watch helplessly. There is no going back once symptoms have started.

One third of rabies cases may present as slow, ascending paralysis of legs and arms, followed by weakness of cranial nerves and muscles of respiration, similar to the condition of Guillain Barre Syndrome. Approximately one third of patients have the paralytic form, but this occurs more commonly with bat rabies, and only a history of animal bite may lead one to suspect rabies. History taking in a patient presenting with these symptoms is therefore important. The condition is also fatal.

Without the benefit of appropriate laboratory tests or a rabies experienced veterinarian it is not possible to accurately diagnose rabies in the rogue animal. Hence one depends upon the animal’s observed behavior, i.e. “sick looking”, apathetic or aggressive, chewing strange objects, glazed look, or simply “abnormal behavior”.

Human rabies, too, is a clinical diagnosis. Rabies virus antigen at neck hair follicles demonstrated by ?uorescent antibody technique (FAT) or immunohistochemistry have rarely been of clinical value

Treatment of Dog Bite:
	1) Wearing protective latex gloves immediately flush the wound/s with clean, flowing tap water and scrub with ordinary soap and water. If the wound is deep, flush with a saline filled syringe. Severe wounds are often contaminated with dust and dirt from the street. By proper cleansing for 10 – 15 minutes, dirt and saliva should be removed and then a local antiseptic like pyodine (but not tincture iodine as this causes skin and tissue burn), should be applied. Soap causes denaturing of the virus protein and destroys the virus Proper and early wound cleansing can reduce chances of developing rabies by 1/3rd Wound washing should actually be taught in the community to save time and improve outcome before the victim reaches a hospital. Do not suture as surgical manipulation further traumatizes the tissues and pushes the virus deeper. 2) Wound categorization is essential to help guide further management
	Category depth Action I No risk • Touching or feeding of animals, licks on intact skin Reassurance only No vaccine needed II Moderate risk • Nibbling of uncovered skin. Minor scratches or abrasions without bleeding Start Vaccine series Day 0 III High risk - Single or multiple transdermal bites or laceration. - Scratches on broken skin contaminated with saliva. - Contamination of mucous membrane of eyes, mouth, nose or wounds with saliva or discharges from rabid animals. Start Vaccine Series Day 0 Plus infiltrate RIG into wound at same time
	3) Rabies Vaccines The purpose of using vaccine is to get the the immune system to produce antibodies against the virus actively. A protective antibody level of 0.5 IU/ml or more is achieved in 2 weeks after giving the first 3 doses of the Essen regimen. Thereafter, the 4th and 5th doses boost the immune response further and maintain the protective levels even a year later. Cell culture Vaccines available in Pakistan:
	TCV Brand Name Pharmaceutical Volume Purified Vero Cell Vaccine (PVRV) Verorab® Abhayrab® Sanofi Pasteur, France Human Biolog. Institute, India 0.5 ml 0.5 ml Purified Chick Embryo Cell (PCEC) Rabipur® Novartis Vaccines Switzerland 1.0 ml Purified Duck Embryo Vaccine (PDEV) Lyssavac ® Zydus Cadilla, India 1.0 ml
	Essen Regimen: is the gold standard for PEP Schedule: Day 0, 3, 7, 14, 28 (5 vials, 5 visits) Day 0 is the day the first dose is given IM into the deltoid Thai Red Cross (TRC) - ID regimen. In an effort to decrease vaccine volume and make quality cell culture products affordable WHO has developed intradermal (ID) schedules which, if properly administered, have the same efficacy as the intramuscular regimen TRC - ID regimen requires 4 outpatient visits. In order to treat 5 patients, you use 1 vial of PCEC (1 ml) or 2 vials of PVRV (0.5 ml each). Give two 0.1 ml on days 0, 3, 7, 28 (called 2-2-2-0-2 regimen. 0 means none on day 14). - Insert the tip of the needle, bevel upwards, and almost parallel to the skin surface of the upper arm and slowly inject the vaccine into the uppermost layer of skin. A raised papule should begin to appear immediately causing orange peel appearance. The procedure is similar to giving BCG intradermally. Give the patient a vaccine record and return appointment Rabies Immune Globulin (RIG) Since the incubation period of rabies may be several weeks to months, it is important to give immediate protection by giving passive, prepared antibodies that neutralize the virus on site. RIG provides protection for the first 14 days until the vaccine takes effect. RIG must be given in all Category III wounds once, at the same time as the vaccine on Day 0. It may be given up to Day 7, but not later since it is likely to interfere with vaccine induced antibody production. ERIG is from heterologous (horse) serum. The dose is higher and it is less costly than Human RIG. A skin test must be done. Weigh the patient and calculate the exact quantity required of RIG. Do not guess or estimate the dose. Excess dose of RIG may suppress antibody production from vaccine. Dose: 40 IU/kg Wearing latex gloves infiltrate into the depth and around all sides of the wound in all directions, to neutralize virus particles. If there is any remaining RIG, inject into a muscle away from the vaccine site.

Prognosis
	Once symptoms of rabies have emerged, the disease is 100% fatal

www.idspak.org
www.rabiesinasia.org
http://www.worldrabiesday.org/EN/mediacenter/perspective.html
www.rabiescontrol.net/ARCnewsletter10.pdf
linkerstrade@gmail.com
www.who.int/zoonoses/
www.who.int/neglected_diseases/diseases/zoonoses/en
www.who.int/zoonoses/vph/en/
www.who.int/rabies
Rabnet: www.who.int/rabnet