Zoonosis: An infection or infectious disease transmissibleunder natural conditions from vertebrate animals to man.e.g.,•Rabies•Anthrax•Undulant fever/ brucellosis/ malta fever•plague/ black death•Tetanus ( locked jaw)•Bovine tuberculosis etc.
RabiesPrimarily zoonotic disease of warm blooded animals particularly carnivores e.g.,Dogs, foxes, cats, tigers, jackals, wolves.Characterized by :Classical hydrophobiaLong and highly variable incubation periodA short period of illness due to encephalitis ending in death.Only communicable disease which is always fatal despite intensive care.
Source of infection: saliva of rabid animalsReservoir of infection: in 3 epidemiological forms1. Sylvatic (wild life) rabies – wild life cycle perpetuated by jackals, foxes, tigers etc; unidentified reservoir of infection.2. Urban areas:From wild life to domestic dogs and maintained by them i.e., from dogs to dogs which leads to 99% of human cases.3.Bat rabies:Vampire bat – importanceProvides constant source of infection for wild animals thus enabling virus to be present in nature.Agent: Lyssa-virus type I family Rhabdo viridae
Mode of transmission:Animal bitesLicks over abraded/ un-abraded skinAerosols (respiratory)Person to person rare but on recordIncubation period:6-60 days but highly variable otherwise at site, severity, no dose.
EpidemiologyWhere: Approx. 40 countries including England, Japan, New Zealand are reported to be free of rabies because of strict importation of animals.In Indo-Pak subcontinent, it is a major public health problem due to large number of stray dogs.WHO(population at risk):Dog-handlersLab-workersCave-explorers (bat rabies)VeterainariansHuntersWild-life officers etc.When : endemic
P.O.C: In days 3-5 before the onset, rarely communicable from man to man.Susceptibility/ Resitance: No natural immunity, prophylactic anti-rabies if started will prevent the disease.Diagnosis:History of exposureClinical signs/ symptomsMicroscopic examination Characteristic eosinophilic inclusions(Negri – bodies)can be found inside nerve cells particularly in hippocampus and this is pathognomic sign in rabies.
Method of ControlDog detention for 10 days, if dies – Rabid.Pets – preventive vaccinationDestruction of stray dogsPets – leash applicationPublic – health educationIf animal clinically rabid, even though the P.M brain examination fails to reveal negri-bodies vice versa or animal disappears after bitingun-identified, un-provoked attack, bitten by wild animals – control of infected - person, contract environment.
PreventionPost exposure prophylaxis:Local treatment of woundImmunization + ARS ( N.T.V D.E.V H.D.C.V)Pre-exposure prophylaxis:Population at risk should be vaccinatedPost exposure treatment of persons previously vaccinated.
Beware of friendly animal (rabies and its treatment) Mode of infection:• Animal bite• Contamination of wound by virus laden saliva Media of transmission:SalivaUrineTearsSerumOther body fluids
Routes of transmission:Licks on damaged skinBites or scratchesInhalationCrossint through intact mucous membranesContamination of wounds Incubation period: Highly variable ranging from few days to several years (commonly 30-90 days) depends upon the site & intensity of bite. Long incubation period makes rabies a suitable disease for post exposure prophylactic immunization.
Concept of therapy:Neutralization or removal of virus before its lodging on the nerveEnhancement of body immune system for long lasting antibody response.No lab tests (antibodies titre) are required before initiation of anti-rabies treatment.
Prevention & Treatment Pre-exposure prophylaxis (PEP):3 standard IM doses of cell-cultured vaccine on day 0, 7, 21, 28. Persons who are in close contact or at high risk e.g., rabies research & diagnostic lab-workers, rabies biological product workers, spelunkers, veterinarians, animal control & wild life workers, animal hunters. Post exposure management:Local wound treatmentVigorous cleansing of wound with soap water, detergent, ether, alcohol or aqueous sol. of Iodine.Avoid wound suturing until and unless unevitableAnti-tetanus injectionAnalgesics & antibiotics symptomatically
Active immunization: Semple type( sheep brain suspension) – 2.5ml SC for cosecutive 14 days on anterior abdominal wall, followed by 2 boosters with 10 days interval & 3 rd booster dose on 90th day Intramuscular regimes: Essen schedule (5 doses)On day 0, 3, 7, 14 & 28 or 30 plus RIG (only once as soon as possible) Reduced or Alternate regime: (4 doses) 2-1-1 on day 0, 7 & 21 2 doses on day 0 plus RIG 3rd on day 7 4th (last) on day 21 Previously immunized persons: Having adequate rabies antibody titre , if exposed again, require 2 doses of ant-rabies vaccine on days 0 & 7.
Recommended Standard Protective Rabies anitbody titreRecommended WHO rabies antibody titer is 0.5IU/ml, 25-30 days after 5th or last injectionRabies antibody titer has no significance before initiation of treatment.If the titer is below the required level, booster dosage should be administered.The protection afforded lasts for 6 months from the completion of anti-rabies treatment.For long term protection, 1st booster after one year & subsequent booster after 5 years.
Method of AdministrationIntramuscular injection into deltoid region or antero-lateral part of the thigh in small children.Infiltrate half of the dosage of RIG in & around the wounds locally & remaining should be administered distant from the site of vaccine administration.Never inject vaccine or sera into gluteal region because of dalayed absorption.Use different syringes each time.
Dosage Human Rabies Immune-globulin (HRIG) 20IU / kg body weight.Equine Rabies Immune-globulin (ERIG) 40IU / kg body weight.Dilute 2-3 folds with sterile saline solution if the calculated dosage of RIG is insufficient to infiltrate all wounds.Skin testing should be performed with ERIG and if found to be positive, treatment should proceed but precautionary measures should be at hand & observe the patient for at least one hour after injection. A negative skin test must never reassure the physician that no anaphylactic reaction will occur.
WHO Guidelines for Post exposure treatmentCategory Type of contact with suspected or Recommended Treatment confirmed rabid or wild animal or animal unavailable for observationI •Touching or feeding of animals None required if reliable •Licks on intact skin history is availableII •Nibbling of uncovered skin •Administer vaccine •Minor scratches or abrasions without bleeding immediately •Licks on broken skin •Stop treatment if animal remains healthy throughout an observation period of 10 days or if animal is euthanized & found to be negative for rabiesIII •Single or multiple transdermal bites or •Administer rabies immune- scratches globulin & vaccine •Contamination of mucous membrane with immediately saliva i.e., licks •Stop treatment if animal remains healthy throughout an observation period of 10 days or if animal is found to
Exposure to hare and rodent seldom, if ever, requires specific anti-rabies treatment.If an apparently healthy dog or cat in or from a low risk area is placed under observation, it may be justified delaying the specific treatment.This observation period applies only to dogs and cats.
AnthraxThis is an acute bacterial infection of animal transmissible to man.ANTHRAX / ANTHRACOSISOrganism: Bacillus-AnthracisSource: tissue, skin & hides, hair & wool of animals dying of anthrax.Reservoir: farm animals / infected cattle, sheep, goats & horses.Occurrence: wide spread in agricultural areas
Mode of Transmission According to Clinical form1-Cutaneous anthrax or malignant pustule – contact of spores over skin of population at risk. Sequence of events: Small red indurate area Later becomes edematous and soft Lastly become hard, edematous & necrotic Also characterized by lymphadenopathy, cellulitis & septicemia.
2- Inhalational anthrax or Wool sorter’s disease (W.S.D) or pulmonary anthraxOccurs due to inhalation of infected material3- Intestinal or ingestion material:Ingestion of infected meat / other material.Incubation period 1-7 days
Preventive/Control Measures1-Animals: Sick must be isolated and treated. Carcases 6feet buried or burnt.Precaution: Never opened or bledVaccination with alum precipitated antigen of animals.2-Factors:Control of effluentsTrade-wasteDust control / ventilation
3- At Community level:Health educationMedical care of skin4- Material :Disinfection:Hair – steamingWool – formaldehydeHides – bin chloride of formic acid /HClIn epidemic – quarantine for 10 days.