1 / 42

RABIES

RABIES. Atilla Kiss M.D. Prepared by Kellie Zaylor D.O. January 4, 2006. Epidemiology. In the Third World: An estimated 40-70,000 people die from the disease each year Rare in U.S. 40 cases/year prior to vaccination of domestic animals that began in 1947 3 cases/year now reported.

ivanbritt
Télécharger la présentation

RABIES

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. RABIES Atilla Kiss M.D. Prepared by Kellie Zaylor D.O. January 4, 2006

  2. Epidemiology • In the Third World: An estimated 40-70,000 people die from the disease each year • Rare in U.S. • 40 cases/year prior to vaccination of domestic animals that began in 1947 • 3 cases/year now reported

  3. Epidemiology • World wide: Dogs most commonly infected and cause more transmission to humans • Bats: An important source in North & South America and Mexico.

  4. Epidemiology: United States • In U.S.- >90% of rabies occurs in wild animals: Principal reservoirs are racoons, skunks, foxes and bats

  5. Rabies Carriers

  6. Skunks & Racoons • Eastern Seaboard: Rabies is endemic in racoons • Only one human case of rabies from a racoon variant has ever been documented (no history of exposure is known) • North Central, South Central and California: Skunks are important carriers, each with its own regional viral strain

  7. BATS • Rabid bats account for 17% of all cases of rabies in U.S. animals • Hawaii- is rabies-free. There are no rabid bats or rabid terrestrial animals.

  8. Human Cases • Between 1990-2003: 39 cases diagnosed with 32 likely acquired in U.S. • 88% (28 cases) associated with bats • 2 cases associated with the dog and coyote populations of Texas • 1 with a racoon in VA. • 1 with a mongoose in Puerto Rico

  9. Human vs. Bat • In most cases, history of bat contact was obtained after patient’s death. • In 3 cases: victim was aware of the bite, but didn’t seek rabies prophylaxis • In half of cases: victim had bat contact, but no bite history • No history of bat exposure for the remaining victims

  10. Disease Principals • Rabies is not a zoonosis: Animals that get infected will die. • Death occurs within 3-9 days after they first begin secreting virus in their saliva. They can transmit the virus at this point. • Exceptions: Some animals can get sick before virus is found in saliva or may not become ill until several days after virus is secreted.

  11. Disease Principals • Bats can live 10 days after infection • Has been suggested dogs can become asymptomatic carriers, but transmission from one has never been documented • In U.S. all rabid dogs die within 8 days of becoming ill; median 3 days.

  12. Animal Behavior

  13. Animal Behavior • Classic Picture of rabid, mangy dog foaming at the mouth…not often seen, signs frequently more subtle. • Animals can display aggressive behavior, ataxia, irritability, anorexia, lethargy or excessive salivation.

  14. Animal Behavior • Cats are more likely to be aggressive than dogs • Animals exhibit change in instinctive behavior: nocturnal animal walking around in daylight (i.e. raccoons) • Unprovoked bites

  15. Transmission • Almost all transmission is by bite • 50 times greater risk than a scratch • One human case may have been acquired in a laboratory (transmitted by aerosol)

  16. Transmission • In wild animals: Rabies can be transmitted transplacentally • Transplants in human- possible • Human-to-human: Never has been confirmed • Rabies virus never isolated from blood

  17. Virus lifestyle • Virus replicated in muscle cells near site of bite for most of incubation time. • Incubation time 30-90 days. Latency up to 7 years • Then ascends along motor and sensory axons at rate of 12-100mm/day and has predilection for brainstem and medulla • Enters salivary glands after replication in CNS.

  18. Rabies virus • Risk of developing rabies after a bite: 5-80%. • Depends upon…. • Severity of exposure • Location of the bite • The biting animal • **Bites on head and neck have shorter incubation time (as short as 15 days) because of rich peripheral nerve supply

  19. Clinical Features • Prodrome: HA, fever, rhinorrhea, sore throat, myalgias, GI upset. *Back pain and muscle spasms. • Agitation and anxiety may result in diagnosis of psychosis or intoxication • Paresthesias, pain or severe itching at site may be the first neurological symptom.

  20. Clinical Features • Over several days symptoms progress • Rabies takes two forms: “Furious”/Encephalitic form: agitation, hydrophobia, extreme irritability, hyperexcitability periods fluctuate with lucidity. • Vitals abnormal: tachycardia, tachypnea, fever

  21. Encephalitic Form • Hydrophobia: Patient can’t swallow because violent jerky contraction of diaphragm and accessory muscles of inspiration when pt attempts to swallow liquids - Patients will be terrified during this reaction and may even experience this at the sight of water or if water touches their face.

  22. Encephalitic Form • Aerophobia: an extreme fear of air in motion can be elicited from some patients. This can also cause violent muscle spasms in the neck and pharynx. • Hallucinations, seizures, ataxia, focal weakness and arrhythmias can occur.

  23. Paralytic Rabies • Other form is “dumb” or paralytic rabies. Similar to Guillain-Barre. • Prominent limb weakness. Consciousness initially spared • Two forms can overlap or progress from one to the other • Coma after one week of neuro symptoms with death a few days after.

  24. Management • Once symptoms occur: fatal in 3-10 days • ICU support: can prolong 4 months. • Six patients have survived clinical rabies: 5 had pre or postexposure prophylaxis before onset of symptoms

  25. Clinical Case • In Wisconsin 2004: 15 year old girl bitten on left index finger by a bat after picking it up off a floor and releasing it outside of her church. • Pt cleaned wound with hydrogen peroxide but did not seek help because the belief that sick/rabid bats could not fly.

  26. Clinical Case • 1 month after bite, c/o fatigue, parasthesias in left hand. Two days later: unsteady, diploplia, nausea/vomiting. • Referred to neuro from pediatrician: MRI/MRA normal and sent home.

  27. Clinical Case • Fourth day of illness: symptoms cont’d. Admitted for LP and supportive care. • CSF: wbc 23 cells • 93% lymphocytes • RBC 3 cells • Protein 50 mg/dL • Glucose 58 mg/dL

  28. Clinical Case • Over next 36 hours: slurred speech, nystagmus, tremors in left arm, lethargy, temp of 102. • Sixth day: bat-bite history reported and rabies considered in differential and transferred to tertiary care center. • Upon arrival: Temp 100.9, impaired muscle coordination, difficulty speaking, double vision, muscle twitching, tremors, obtunded.

  29. Clinical Case • Blood, CSF, nuchal skin samples, saliva submitted to CDC. • Pt developed hypersalivation and was intubated. • Rabies-virus specific antibodies were detected in serum and CSF. No evidence found in nuchal skin biopsies and saliva.

  30. Clinical Case • Management: drug-induced coma and ventilator support for 7 days • IV ribavirin • CSF antirabies IgG: from 1:32 to 1:2,048 • Meds tapered, on 33rd day of illness, extubated, 3 days later transferred to rehab. • Unable to speak, could walk with assistance and feed herself. • Prognosis for her full recovery is unknown.

  31. Management • No effective treatment exists. • Postexposure Prophylaxis/PEP: 3 steps • 1. Wound care: immediate thorough washing with soap and water and a virucidal agent such as povidine-iodine or 1-2% benzalkonium chloride. • Shown to be protective if performed within 3 hours of exposure • If puncture, swab deeply in wound and around edges

  32. PEP • 2. Passive Immunization: Human rabies immunoglobulin (HRIG) 20 IU/kg ASAP, but not longer than 7 days after vaccine given. Infiltrate entire dose around wound, any remaining IG inject IM at a site distant from the vaccine. • 3. Human diploid cell vaccine (HDCV): 1 ml (deltoid) on days 0,3,7,14,28.

  33. PEP • Vaccine: do not give in gluteal. If injected into fat, no antibodies formed. • HRIG and HDCV: give in different anatomical sites and never in the same syringe.

  34. PEP • Local Reactions: itching, erythema, pain, swelling • Systemic: HA, myalgia, nausea. • Anaphylaxis: .1% of cases • Guillain-Barre: 3 cases • Angiodema: 6% of pts who receive boosters. • Can give PEP during pregnancy

  35. Who should get PEP? • Type of exposure • Location of incident (head/neck) • Species of biting animal (common carrier of rabies?)

  36. WHAT IS A SIGNIFICANT EXPOSURE?

  37. Significant Exposure

  38. Significant Exposure

  39. Significant Exposure • Bites are significant • Nonbite exposures that involve contamination of either mucous membrane or open wound (bled within 24 hours) with saliva • Not significant: petting a rabid animal, contact with its blood, urine, feces. • Skunk spray • Dry virus: NOT INFECTIOUS

  40. Animals in captivity • Wild animals that are caught should by euthanized immediately and head sent under refrigeration to an appropriate lab for testing. • Domestic animals that are apparently healthy should be observed for 10 days. If animal doesn’t become ill, victim does not require treatment. • If animal gets sick, euthanize and test immediately.

  41. References • Chapter 129: Rabies. Rosen’s Emergency Medicine • CDC : http://www.cdc.gov/ncidod/dvrd/rabies http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5350a1.htm • WHO: http://www.who.int/mediacentre/factsheet/fs099/en

More Related