RABIESDr.Muhammad Umair

Pharm.D, M.Phil. Clinical PharmacyLecturerLahore Pharmacy College OfLahore Medical & Dental College (Pakistan)

Rabies

• Zoonotic viral infectious diseases; almost invariably fatal

• Virus attacks on the nerves system and later excreted in saliva

• A person can become victim in following ways;• Bites of diseased animals• Non-bites exposure• Human to Human Transmission

Virology

• Rabies virus belongs to Lyssavirus genus of Rhabdoviridae family

• Virus is enveloped and has a single stranded RNA genome

• All rahbdoviruses have two major structural components;• Helical ribonucleoprotein core (RNP)• Surrounding envelops

Epidemiology• Asia

• Most of the developing countries in Asia are the victims

• Over 30,000 people die every year due to rabies in Asia

• 15% are likely to be the children under 15 years

• India, Srilanka, Bangladesh, Pakistan, Nepal are high risk areas

• Africa• More than 24,000 deaths per year in Africa• Majority of them are from poor rural

communities or children• Angola, Namibia, Mozambique, Zimbabwe are

high risk areas

• Europe and united states• On verge of disappearance from

many countries• Policy of animal vaccination

Rabies free zones

Pathogenesis

• Transmission• Bite of a rabid animal (Dogs, Bats, Racoons, Foxes,

Skunks)• Contamination of scratch wounds by virus infected

saliva

• Incubation• Replication in the striated or connective tissue at the

site of inoculation• Enters the peripheral nerves through the

neuromuscular junction

Clinical manifestation• Initial symptoms (Prodrome)• nonspecific

• Neuropathic pain at site of bite pruritus tingling

• Fever, anxiety, and malaise• The initial symptoms of rabies are often vague and it can be easy to

mistake them for other, less serious, types of infection. They include:• Fever• Headache• Feeling generally unwell• Feeling scared or anxious

• After 2–10 days neurological signs appear• Encephalitic and Paralytic forms• Encephalitic manifestations

• May appear in episodes• cerebral dysfunction and autonomic

dysfunction• Agitation, confusion, hydrophobia,

aerophobia,• hyperventilation, hyper-salivation, priapism,

and convulsions

• Paralytic manifestations• Peripheral nerves accompanied by fever• Within 2–12 days, coma and cardiorespiratory

failure starts

• Advanced symptoms• After 10-14 days of prodromal phase, more severe

symptoms start to develop.• Aggressive behaviour, hallucinations, agitation and

producing lots of saliva• Paralysis, and eventually death

Clinical forms ofrabies

• Encephalitic = furious• ~ 80%

• Paralytic = dumb• ~ 20%

Encephalitic rabies

• Prodromal symptoms• Paresthesia, Pain, Pruritus at site of bite• Episodes of generalized arousal or hyper-excitability

separated by lucid periods• Autonomic dysfunction• Hydrophobia

Paralytic rabies• Paresthesia, Pain, Pruritus at site of

bite• Early flaccid muscle weakness• Often begins in bitten extremity• Progresses to produce Quadriparesis

• Bilateral facial weakness• Sensory examination is usually

normal• Sphincter involvement• Fatal outcome• Often misdiagnosed as Guillain -

Barré syndrome

Diagnosis

• Tests are also performed on the samples of saliva, serum, and skin biopsiesof hair follicles at the nape of the neck

Human rabies prevention

• Pre-exposure prophylaxis

• Post-exposure management

Post-exposure immunization individuals

not previously vaccinated• Wound site(s)• Immediate thorough cleansing of all wounds with

soap and water.• Tetanus prophylaxis; antibiotics

• Human Rabies Immune Globulin (RIG)• 20 IU/kg body weight• As much of the RIG as possible should be

infiltrated in wound(s)• The remainder should be given IM at a site

distant from vaccine• Rabies Vaccine

• IM (1 mL) in the deltoid area on days 0, 3, 7, 14, and 28

Pre-exposure prophylaxis

• Populations at increased risk of exposure to rabies• Rabies research laboratory workers

• Veterinarians, staff, veterinary students

• Animal control and wildlife workers

• Bat handlers

• Spelunkers

• Travellers to certain rabies-endemic areas

• Rabies Vaccine• 3 doses of rabies vaccine (days 0, 7, and 21

or 28)• May check rabies antibody titer periodically

(>0.5 IU/mL)

• After a rabies exposure• 2 doses of IM rabies vaccine (days 0 and 3)

•No HRIG