10. World Rabies Day
• …… to reduceto reduce
the sufferingthe suffering
from rabiesfrom rabies
11. At the end of session you will learnAt the end of session you will learn
• Rabies: an invariably fatalRabies: an invariably fatal encephalitisencephalitis
• Only mammals affectedOnly mammals affected
• Always endemic in the wildAlways endemic in the wild
• VirusVirus descendsdescends from brain to salivary glandsfrom brain to salivary glands
• 90% are from rabid dog90% are from rabid dog
• Bats spread it byBats spread it by aerosolaerosol
• It can be prevented (100%)It can be prevented (100%)
• Bangladesh stands 2Bangladesh stands 2ndnd
in mortalityin mortality
12. Key factsKey facts
• Globally >Globally >60k deaths/60k deaths/yy in >in >150150 countriescountries
• 1111thth
biggest c/of deathbiggest c/of death
• 95% in Asia Africa95% in Asia Africa
• 50% children50% children
• India: (~30k)India: (~30k)
• Wound cleansing & immunization can prevent itWound cleansing & immunization can prevent it
• Bangladesh: mBangladesh: most people are unprotectedost people are unprotected
• Rabies costs theRabies costs the world $124 billion/yworld $124 billion/y
13. What is Rabies?What is Rabies?
• .. a zoonosis c/by.. a zoonosis c/by rabiesrabies virusvirus
• Infects both domestic & wild animalsInfects both domestic & wild animals
• Causes ac. EncephalitisCauses ac. Encephalitis
Symptomatic rabies:Symptomatic rabies: 100% fatal100% fatal
14. Rhabdo/lyssa viruses
• Bullet shaped.Bullet shaped. RNARNA
• EnvelopedEnveloped
• Killed byKilled by ethanol ether, iodine,ethanol ether, iodine,
soap/detergents,soap/detergents,
chloroform, acetone, heatchloroform, acetone, heat (60(6000
cc
x5 min)x5 min)
Lyssa means rageLyssa means rage
15. EpidemiologyEpidemiology
• Fixed virusFixed virus (lab virus)(lab virus):: R. virus after serial passage throughR. virus after serial passage through
rabbits to stabilize its virulence & IPrabbits to stabilize its virulence & IP
• Street virus:Street virus: wild viruswild virus
• Primary reservoirs:Primary reservoirs: wild mammalswild mammals
• OnlyOnly mammalsmammals affected; exceptaffected; except mice !mice !
• ManMan, dogs, raccoons, skunks, foxes, bats, cats, cattle, dogs, raccoons, skunks, foxes, bats, cats, cattle
commonlycommonly affectedaffected
• It is endemic in many countriesIt is endemic in many countries except Australia, Malaysia,except Australia, Malaysia,
Japan, Bhutan, NepalJapan, Bhutan, Nepal
IP: incubation periodIP: incubation period
23. Pathogenesis ..Pathogenesis ..
• RV replicates in muscles: enters nerves & ascends toRV replicates in muscles: enters nerves & ascends to
CNS (CNS (3 mm/h)3 mm/h)
• Spread within CNS is rapidSpread within CNS is rapid
• Then spreads centrifugally by nerves to salivary g., eyes,Then spreads centrifugally by nerves to salivary g., eyes,
kidneys, breastskidneys, breasts
• This time the classic CF developThis time the classic CF develop
RV: rabies virusRV: rabies virus
25. HistopathologyHistopathology
• EncephalomyelitisEncephalomyelitis
• Perivascular inflammatory cellsPerivascular inflammatory cells
• Neuronal cytoplasmic inclusion (Negri bodies)Neuronal cytoplasmic inclusion (Negri bodies)
esp. in pyramidal cellsesp. in pyramidal cells
• Inclusion bodiesInclusion bodies (elementary bodies):(elementary bodies): are nuclear/cytoplasmic aggregates; usuallyare nuclear/cytoplasmic aggregates; usually
proteins: typically represent sites of viral replication & consist of viral capsidproteins: typically represent sites of viral replication & consist of viral capsid
• Pyramidal neurons (pyramidal cells):Pyramidal neurons (pyramidal cells): found infound in c. cortex, hippocampus, & amygdalac. cortex, hippocampus, & amygdala..
They are primary excitation units of mammalian prefrontal cortex &They are primary excitation units of mammalian prefrontal cortex &
corticospinal tractcorticospinal tract
26. Early CF: (often vague)Early CF: (often vague)
• Flu-like:Flu-like: malaise, F:malaise, F: 38C or above38C or above, chills, HA, f, chills, HA, fatigue,atigue,
problems sleeping, anorexiaproblems sleeping, anorexia
• Anxiety, irritability, sore throatAnxiety, irritability, sore throat
• Discomfort/ paresthesiaDiscomfort/ paresthesia at bite site (50%)at bite site (50%)
• BBizarre behavior, fear of death!izarre behavior, fear of death!
On progression:On progression: neuro-symptoms:neuro-symptoms:
28. Furious rabiesFurious rabies
• anxiety, confusion, insomnia, nervousness, seizure,anxiety, confusion, insomnia, nervousness, seizure,
aggressivenessaggressiveness,, hallucinations, delirium, fear of deathhallucinations, delirium, fear of death
• biting,biting, delusions, HGF, hyperhydrosis, goose skin, priopism,delusions, HGF, hyperhydrosis, goose skin, priopism,
hypersalivation, dysphagia,hypersalivation, dysphagia, hydro-phobiahydro-phobia (50%),(50%),
aero-, photo-: aaero-, photo-: a few days later coma & deathfew days later coma & death
Dumb/paralytic rabiesDumb/paralytic rabies
• S/of partial/full paralysisS/of partial/full paralysis usually begins in limbs & spreadsusually begins in limbs & spreads
all overall over
• Hydrophobia isHydrophobia is unusualunusual
• Progress to coma & death (heart or lung failure)Progress to coma & death (heart or lung failure)
29. A rabid dog displayingA rabid dog displaying
the classic form ofthe classic form of
paralytic R, cranial-paralytic R, cranial-
nerve deficits &nerve deficits &
hypersalivationhypersalivation
30. Routine rabies tests:Routine rabies tests:
• Direct fluorescent Ab. test (dFA:) (only post mortem)Direct fluorescent Ab. test (dFA:) (only post mortem)
• Biopsy:Biopsy: NegriNegri bodies. Immunohistochemistry (IHC). EMbodies. Immunohistochemistry (IHC). EM
Importance:Importance:
• For timely post-exposure prophylaxis (PEP) orFor timely post-exposure prophylaxis (PEP) or
• avoid unnecessary physical & psychological traumaavoid unnecessary physical & psychological trauma
Diagnosis in AnimalsDiagnosis in Animals
31. dFAdFA detects RVdetects RV
• Ideal tissue is nerve (brain)Ideal tissue is nerve (brain)
• Fl. anti-rabies Ab incubated with brain tissue fixes RV; seenFl. anti-rabies Ab incubated with brain tissue fixes RV; seen
by Fl. MC. Unbound Ab can be washed awayby Fl. MC. Unbound Ab can be washed away
IHCIHC
• Like dFA, IHC uses sp. Ab to detect RV inclusions in tissues.Like dFA, IHC uses sp. Ab to detect RV inclusions in tissues.
More sensitive than histopathologyMore sensitive than histopathology
Fl: fluorescence. MC: microscopeFl: fluorescence. MC: microscope
33. • Negri bodiesNegri bodies are pathognomonic incl. bodies in cytoplasmare pathognomonic incl. bodies in cytoplasm
of certain nerves (of certain nerves (only in 20%)only in 20%)
34. Rabies Dx in HumansRabies Dx in Humans
• No test available before cl. diseaseNo test available before cl. disease
• Confirmed pre- & post mortem by detecting RV, viral Ag inConfirmed pre- & post mortem by detecting RV, viral Ag in
brain, skin, urine, salivabrain, skin, urine, saliva
• Saliva is tested by reverse transcription followed by PCR (RT-Saliva is tested by reverse transcription followed by PCR (RT-
PCR)PCR)
• Antibody: serum, CSFAntibody: serum, CSF
Ag: antigenAg: antigen
35. PreventionPrevention
• Vaccinating pet & killing stray dogsVaccinating pet & killing stray dogs
• Vaccine for at risk personsVaccine for at risk persons
• Care of biteCare of bite
• No contact with stray/wild animals. Don’t capture orNo contact with stray/wild animals. Don’t capture or
provoke stray animalsprovoke stray animals
• Not touching animal carcassesNot touching animal carcasses
• Secure garbageSecure garbage
• Cover chimneys & other entrancesCover chimneys & other entrances
36. • If bitten by bats, skunks, foxes, other carnivoresIf bitten by bats, skunks, foxes, other carnivores
• regard as rabid unless the area is R free or until animalregard as rabid unless the area is R free or until animal
is negative by lab testingis negative by lab testing
• immediate immunization & HRIGimmediate immunization & HRIG
• Bites by squirrel, gerbil, hamster, G. pig, rat, mice, otherBites by squirrel, gerbil, hamster, G. pig, rat, mice, other
rodents, rabbits, hare almost never require anti-R Rxrodents, rabbits, hare almost never require anti-R Rx
HRIG: human rabies immunoglobulinHRIG: human rabies immunoglobulin
Prevention …Prevention …
39. Who should get the Vaccine?Who should get the Vaccine?
Pre-exposurePre-exposure
• High-risk people:High-risk people: vets., animal handlers, R. lab. workers,vets., animal handlers, R. lab. workers,
cave/wild explorers, forestry workers,cave/wild explorers, forestry workers, travelers intravelers in
endemic areas,endemic areas, people having frequent contact with R.people having frequent contact with R.
virusvirus
• 3 doses: 0-7-21/283 doses: 0-7-21/28thth
d d
BenefitsBenefits
• No need of HRIG, less post-expo. vax. dosesNo need of HRIG, less post-expo. vax. doses
• Post exposure Rx might be delayedPost exposure Rx might be delayed
• Protects from inapparent exposures to R.Protects from inapparent exposures to R.
• For repeated exposure screen for boosterFor repeated exposure screen for booster
40. Post-exposurePost-exposure
• Bitten by an animal, or contactBitten by an animal, or contact
• 4 doses: 0-3-7-144 doses: 0-3-7-14thth
daysdays
• They should also get HRIG with first dose vax.They should also get HRIG with first dose vax.
• Pre-vaccinated person get 2 doses: 0-3Pre-vaccinated person get 2 doses: 0-3rdrd
d; no HRIGd; no HRIG
• Should the animal be kept for 10 d?Should the animal be kept for 10 d?
43. Future Rabies VaccinesFuture Rabies Vaccines
• Vax. under dev. may be safe, potent & cheaperVax. under dev. may be safe, potent & cheaper
• DNA vaccinesDNA vaccines, recombinant vaccines, recombinant vaccines
• Plant biotechnology for making AgPlant biotechnology for making Ag
• Neutralizing monoclonal antibodyNeutralizing monoclonal antibody
44. Adverse ReactionsAdverse Reactions
Less in childrenLess in children
• Adults: local reactions (25%), systemic- (20%)Adults: local reactions (25%), systemic- (20%)
• HA, nausea, AP, aches & dizziness (5-40%)HA, nausea, AP, aches & dizziness (5-40%)
• Very rare:Very rare: illness like GBSillness like GBS
• Immune-complex with boosters: hives, arthralgia, F (6%)Immune-complex with boosters: hives, arthralgia, F (6%)
• Different brands differDifferent brands differ
• Anaphylaxis, Anaphylaxis, if any, occurs within a min- to an hr. withif any, occurs within a min- to an hr. with
dyspnoea, hoarseness, wheeze, throat swelling, hives,dyspnoea, hoarseness, wheeze, throat swelling, hives,
pallor, weakness, tachycardia, or dizzinesspallor, weakness, tachycardia, or dizziness
45. Human Rabies IG (HRIG)Human Rabies IG (HRIG)
• Category iii bite:Category iii bite: 20iu/kg20iu/kg
with vax. but different siteswith vax. but different sites
• ½ at the site (infiltrate the½ at the site (infiltrate the
wound); ½ IMwound); ½ IM
46. Basic Care in Animal BitesBasic Care in Animal Bites
• Immediate thorough toileting x15min with soapImmediate thorough toileting x15min with soap
water, detergent, povidone iodinewater, detergent, povidone iodine
• Don't suture!Don't suture!
• Categorize the bite:Categorize the bite:
• Post- exposure prophylaxisPost- exposure prophylaxis
47.
48. Bite CategoryBite Category ((WHO)WHO)
• Category I: 1.Category I: 1. touching/feeding suspect animalstouching/feeding suspect animals
2.2. licks on intact skinlicks on intact skin
• Category II: 1.Category II: 1. nibbling of skinnibbling of skin
2.2. scratches/abrasionsscratches/abrasions, but no hge., but no hge.
3.3. licks on broken skinlicks on broken skin
• Category III:Category III: 1 or more1 or more bites/scratches, licks with hge.;bites/scratches, licks with hge.;
mucosal contamination with saliva, contacts with batsmucosal contamination with saliva, contacts with bats
49. Category ICategory I
no treatmentno treatment
Category IICategory II
wound disinfectionwound disinfection
vaccine onlyvaccine only
51. Category IIICategory III
wound cleansing, HRIG & vaccinewound cleansing, HRIG & vaccine
• Animal observation in our country is not practical:Animal observation in our country is not practical:
frequent bitesfrequent bites
• Delay Rx only ifDelay Rx only if
• Species unlikely to be infectedSpecies unlikely to be infected
• Lab Dx in 48hrLab Dx in 48hr
• Dog >1yr old with current vaccination (observe forDog >1yr old with current vaccination (observe for
10d)10d)
52.
53.
54. To date only 6 cases survivedTo date only 6 cases survived
• Once clinical, rabies is always fatalOnce clinical, rabies is always fatal
• Rx is only supportiveRx is only supportive
• Typically life ends after 2-10 d (6d)Typically life ends after 2-10 d (6d)
No danger of nursing R pts with precautionsNo danger of nursing R pts with precautions
PrognosisPrognosis
56. Shots for Dogs Would Save PeopleShots for Dogs Would Save People
• Mass vaccination for dogs could eliminate it in humanMass vaccination for dogs could eliminate it in human
• R. is rare in HICsR. is rare in HICs
• Lack of international commitment is among the reasonsLack of international commitment is among the reasons
why rabies in people persistswhy rabies in people persists
57. MCQMCQ
• Most rabies are from bite by rabid dogsMost rabies are from bite by rabid dogs
• Most of rabid-dog bites develop into rabiesMost of rabid-dog bites develop into rabies
• HDCV is at present the best ARVHDCV is at present the best ARV
• Rabies is not transmitted by contaminated corneal graftRabies is not transmitted by contaminated corneal graft
• Rabies is always endemic in the forestRabies is always endemic in the forest
• India has the greatest rabies deathsIndia has the greatest rabies deaths
• Bangladesh stands second in mortalityBangladesh stands second in mortality
58. MCQMCQ
• Vaccinating pet dogs is essential to control rabiesVaccinating pet dogs is essential to control rabies
• Everyone should be vaccinated against rabiesEveryone should be vaccinated against rabies
• Rabies virus spread to CNS via bloodRabies virus spread to CNS via blood
• It can be transmitted by foodIt can be transmitted by food
• Saliva contains R virus after brain involvementSaliva contains R virus after brain involvement
• Rabies can be eradicatedRabies can be eradicated
The reservoirs vary based on geographic location; commonly dogs, bats, raccoons, foxes, cats, & skunks.
The primary cause of human rabies worldwide is from dogs
In the US, dogs are vaccinated, the primary c/of R in humans is from wildlife (particularly bats)
Transmission of R usually begins when infected saliva of a host is passed to an uninfected animal. Various routes have been documented: mucosa (eyes, nose, mouth), aerosol, & corneal transplantations. The most common is bite. 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 & indirect entry after viral replication in nonnervous tissue (muscle cells). During the eclipse phase, the host immune defenses may confer CMI against viral infection as R virus is a good Ag. The uptake of virus into PN is important for progressive infection to occur. After uptake into PN, R virus is transported to CNS via retrograde axoplasmic flow. Typically this occurs via sensory & motor nerves at the initial site of infection. IP may vary from a few days to several years, but is typically 1-3 mo. Dissemination of virus within the
CNS is rapid, & 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 &
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
Pathology
R is typically encephalitis & myelitis. Perivascular infiltration with lymphocytes, polymorphs & plasma cells can occur throughout entire CNS. R frequently causes cytoplasmic eosinophilic inclusion bodies (Negri bodies) in neuronal cells, esp. pyramidal cells of the hippocampus & Purkinje cells of cerebellum. These are areas of active replication.
Several factors may affect outcome: virus variant, inoculum, route & location of exposure, as well as individual age & immune defenses
Hydrophobia is a set of symptoms in later stages of R: difficulty swallowing, panic when presented with liquids to drink, & the pt. can't quench its thirst
Aerophobia: pathological aversion or sensitivity to air or its movement, especially as a symptom of R.
Rabies diagnosis in humans
The importance of routine rabies tests
Essential characteristics for routine rabies tests
Laboratory tests for rabies
Direct fluorescent antibody test (dFA)
Antigen detection by dFA
General histopathology
Negri bodies
Immunohistochemistry (IHC)
Ultrastructure Amplification methods
New standard DFA protocol for rabies
Rabies diagnosis in animals
The direct fluorescent antibody test (dFA) is the test most frequently used to diagnose rabies. This test requires brain tissue from animals suspected of being rabid. The test can only be performed post-mortem
Rabies diagnosis in humans
Several tests are necessary to diagnose rabies ante-mortem (before death) humans; no test sufficient. Tests are performed on samples of saliva, serum, CSF, & skin biopsies of hair follicles at the nape of the neck. Saliva can be tested by virus isolation or reverse transcription followed by polymerase chain reaction (RT-PCR). Serum & spinal fluid are tested for antibodies to rabies virus. Skin biopsy specimens are examined for rabies antigen in the cutaneous nerves at the base of hair follicles.
The importance of routine rabies tests
Rapid & accurate laboratory diagnosis of rabies in humans & other animals are essential for timely administration of postexposure prophylaxis.
Within a few hours, a diagnostic laboratory can determine whether or not
an animal is rabid & inform the responsible medical personnel. The laboratory
results may save a patient from unnecessary physical & psychological
trauma, & financial burdens, if the animal is not rabid.
In addition, identification of positive rabies cases may aid in defining current epidemiologic patterns of disease & provide appropriate information
for the development of rabies control programs.
Essential characteristics for routine rabies test
The nature of rabies disease dictates that laboratory tests be standardized,
rapid, sensitive, specific, economical, & reliable.
Laboratory tests for rabies
The standard test for rabies testing is dFA. This test has been thoroughly
evaluated for more than 40 years, & is recognized as the most rapid
& reliable of all the tests available for routine use. All rabies laboratories
in the United States perform this test (post-mortem) on animals suspected
of having rabies. Other tests for diagnosis & research, such as electron microscopy (EM), histologic examination, immunohistochemistry (IHC), RT-PCR, & isolation in cell culture are useful tools for studying the virus structure, histopathology, typing, & virulence of rabies viruses.
Direct fluorescent antibody test (dFA)
The dFA test is based on the observation that animals infected by rabies virus
have rabies virus proteins (antigen) present in their tissues. Because
rabies is present in nervous tissue (& not blood like many other viruses),
the ideal tissue to test for rabies antigen is brain. The most important
part of a dFA test is flouresecently-labelled anti-rabies antibody.
When labelled antibody is incubated with rabies-suspect brain tissue,
it will bind to rabies antigen. Unbound antibody can be washed away &
areas where antigen is present can be visualized as fluorescent-apple-green
areas using a fluorescence microscope. If rabies virus is absent there
will be no staining.
Antigen detection by dFA
The rabies antibody used for the dFA test is primarily directed against
the nucleoprotein (antigen) of the virus (see The Virus section on viral structure). Rabies virus replicates in the cytoplasm of cells, & infected cells may contain large round or oval inclusions containing collections of nucleoprotein (N) or smaller collections of antigen that appear as dust-like fluorescent particles if stained by
the dFA procedure.
Despite evidence that control of dog rabies through programs of animal vaccination & elimination of stray dogs can reduce the incidence of human rabies, exposure to rabid dogs is still the cause of over 90% of human exposures to rabies & of over 99% of human deaths worldwide.
Purpose of PrEP: First, although it does not eliminate the need for additional medical attention after a exposure, it simplifies therapy by eliminating the need for HRIG & decreasing the number of vaccine doses needed – a point of particular importance for persons at high risk of being exposed to rabies in areas where immunizing products may not be available, & it minimizes SE to multiple doses of vaccine.
Second, it may enhance immunity in persons whose postexposure Rx might be delayed.
Finally, it may provide protection to persons with inapparent exposures to rabies.
It consists of 3 doses: on days 0, 7, & 21 or 28
RIG: Rabies Immune Globulin
Vero cells are used in cell cultures; first isolated from kidney epith cells from an African green monkey in 1962
They are used for: screening toxin of E coli ("Vero toxin“ or "Shiga-like toxin“), for growing virus; testing for rabies virus, growth of viral stocks for research purposes, host cells for eukaryotic parasites. The Vero cell lineage is continuous & aneuploid meaning an abnormal number of chromosomes. Vero cells are interferon-deficient; they do not secrete interferon when infected by viruses though they have Interferon receptor
Local treatment of the wound: Removing the RV at the site by chemical or physical means is an effective means of protection, prompt local treatment of all bite wounds & scratches that may be contaminated with RV is important. Immediate & thorough flushing & washing of the wound for a minimum of 15 min with soap & water, detergent, povidone iodine or other substances that kill the rabies virus
Signs & symptoms
The first symptoms of rabies may be nonspecific flu-like signs —
malaise, fever, or headache, which may last for days. There may be discomfort
or paresthesia at the site of exposure (bite), progressing within days
to symptoms of cerebral dysfunction, anxiety, confusion, agitation, progressing
to delirium, abnormal behavior, hallucinations, & insomnia. The acute
period of disease typically ends after 2 to 10 days (6). Once clinical
signs of rabies appear, the disease is nearly always fatal, & treatment
is typically supportive. Disease prevention is entirely prophylactic &
includes both passive antibody (immune globulin) & vaccine. Non-lethal
exceptions are extremely rare. To date only six documented cases of human
survival from clinical rabies have been reported & each included a history
of either pre- or postexposure prophylaxis.