Rabies and Tetanus and Ticks Oh my…

1. Rabies and Tetanus and Ticks Oh my… Heather Patterson PGY3 November 7, 2007

2. Objectives • Review • basic pathophysiology • clinical presentation • management • What this will not be: • Didactic!

3. Describe the rash.

4. Rocky Mountain Spotted Fever Etiology? • Rickettsia rickettsee – found in Rocky Mountain wood tick saliva How many hours does the tick need to feed for innoculation? • 6 hours

5. Rocky Mountain Spotted Fever • R. rickettsii: • Obligate intracellular bacteria • Infect endothelial cells and vascular smooth muscle • Initiates the coagulation cascade • Cellular immune response and complement activation ↓ Increased vascular permeability

6. Rocky Mountain Spotted Fever • Clinical Presentation • Onset: • Day 2-14 after bite (mean 7 days) • Most often abrupt onset but can be gradual (33%) • Symptoms: • Sudden onset fever (>38.3) and rigors – may precede other symptoms by 2-3 days • Myalgias – tenderness in large muscle groups • Headache • Nausea,vomiting, anorexia (80%) • Rash

7. Rocky Mountain Spotted Fever • Classic Triad (3%): • Fever • Rash • Tick bite

8. Rocky Mountain Spotted Fever How does the rash present on day 2-4 post onset fever? • 2-6 mm blanchable, pink macules • Wrists, palms, ankles, soles • Spreads cetripetally 6-12 h post onset

9. Rocky Mountain Spotted Fever How does the rash present on day 4-6 post onset fever? • Non-blanchable petechial rash • Local edema surrounding petechie

10. Rocky Mountain Spotted Fever How do we make the diagnosis? • Based on clinical features • Skin bx with assays– dx can be made in 4h • Serology – drawn 2-3 wks post onset • Labs: • Bands • Thrombocytopenia • ↑Na • ↑ Transaminases

11. Rocky Mountain Spotted Fever • DDx: • Meningococcus • Rubella • Measles • Disseminated gonoccocal • TSS • Mononucleosis • Enteroviral infections • Other infections: dengue, leptospirosis, typhus

12. Rocky Mountain Spotted Fever • Must think of RMSF with unexplained fever even in absence of rash, headache, tick bite, or travel to endemic area

13. Rocky Mountain Spotted Fever • Complications: • Cardiac: • Myocarditis • 1 degree AV block, non-specific ST-T changes • PAT, Afib • CHF • Resp: • Interstitial pneumonitis • Pulmonary edema, effusions, infiltrates • ARDS

14. Rocky Mountain Spotted Fever • Complications: • Neuro: • Eosinophilic meningitis • Encephalomyelitis • Vaculitis +/- thrombosis • Mov’t disorders • Other: • Shock • DIC

15. Rocky Mountain Spotted Fever • Doxycycline • 100mg po bid • 2.2 mg/kg for kids • Tetracycline • 2g/d • Chloramphenicol • In pregnancy or kids <8y Treatment? Duration? • Treat for 2-5 days after afebrile OR min of 7-10 days

16. Rocky Mountain Spotted Fever • Steriods: • Unstable, encephalitis, cerebral edema or “extensive” vasculitis • Mortality: • Untreated >30% • Treated 3-7%

17. Case 2

18. Case 2

19. Lyme Etiology? • Borrelia burgdorferi – spirochete • Vector – deer tick (deer, small rodents) How many hours does the tick need to feed for innoculation? • 24-72 hours

20. Lyme Pathophysiology • Hematogenous spread of spirochete • Affinity for skin, synovial tissue, nervous tissue.

21. Lyme • Classification by stage of infection: • Early Lyme Disease • Acute Disseminated Infection • Late Lyme Disease

22. Early Lyme Disease • Onset: • 1-36 days post innoculation • Clinical features: • Rash (90%) +/- 2º lesions • Lymphadenopathy in same region • Constitutional symptoms “flu-like” • Low grade fever • Malaise, lethary • Migratory arthralgias and myalgias CLUE: Rash is present in 90% Diagnostic

23. Early Lyme Disease • Neuro • h/a • meningeal irritation • photophobia • GI: • N/V • RUQ pain CLUE: Rapidly changing and intermittent symptoms in many systems

24. Erythema Migrans • Characteristics: • Round/oval/triangular/linear • Confluent or targetoid • Sharply demarcated boarders • Flat or raised • Blanch with pressure • Size: • Spreads ~1-2cm/day • Ave size 8-10cm • Secondary lesions • Smaller, migrate less, spare palms and soles

25. Lyme – Acute Disseminated • Acute Disseminated Infection • Onset • Avg 4 wks post innoculation • May overlap symptoms of early or late • Neuro • MC -Fluctuating meningoenceph • Triad • Cranial neuropathy (Bell’s) • Peripheral neuropathy/radiculopathy • Meningitis • CSF • N gluc, ↑prot/lymphs • CLUE: • Multiple neuro features in CNS/PNS • Bilateral Bell’s = Lyme until proven otherwise

26. Lyme • Acute Disseminated Infection • Joint: • Intermittent large joint inflam arthritis • Brief with spont remission • Recurrent • Cardiac: • Dysrhythmias and blocks • Uncommon CLUE: Cardiac: Fluctuating blocks, slow spont resolution Joint: shorter duration, recurrent

27. Lyme - Late • Late Lyme Disease • Joint: • More frequent episodes of arthritis • Becomes chronic • Neuro: • Chronic encephalopathy • Memory and learning abN • Sensory abN • Psych

28. Lyme - Diagnosis • Erythema migrans • endemic area • ELISA test 89% Sens and 72% Spec • Confirmed on Western Blot/PCR • Isolation from tissues and body fluids takes weeks to grow • Impractical clinically

29. Lyme - Treatment • Prophylaxis? • Risk of infection minimal to nonexistent if attached <24hrs • If symptoms develop, ABx curative in most cases • Uncomplicated • PO ABx 14-21 days • Doxycycline 100mg BID for adults • Amoxicillin 50mg/kg divided TID for Peds • Late or severe disease • IV ABx x 30d • Ceftriaxone/PenG/chloramphenicol • Neurologic (other than Bell’s) or cardiac manifestations

30. Case 3 • 18mo F sleeping at the cottage. Parents go in to check on her. There is a bat in the room. • What do you do?

31. Rabies • Bats are a major vector of rabies in North America • Analysis has shown that rabies comes from bats even when there is absence of a bite. • CDC recommends: • Postexposure prophylaxis for anyone exposed to a bat who is unable to give a history of contact : ie sleeping, children etc • Any contact with bat, including saliva • Bat bites

32. Rabies • What is the major animal vector in North America? • Raccoon • What are other common vectors: • Bat • Skunk • Fox • Woodchuck • Other carnivores

33. Rabies • What is rabies? • Bullet shaped RNA rhabdovirus • Previously thought to be a single virus responsible for all rabies • Antigen detection has shown that several viruses and at least 6 serotypes exist

34. Rabies • How is rabies transmitted? • Saliva • Scratches • Aerosolized virus into respiratory tract • Secretions that contaminate MM • Corneal transplants

35. Rabies • How does rabies affect the body? • (what tissue does it primarily affect?) • The virus attacks nerve tissue • Spreads along peripheral nerves and muscle fibers to the CNS • Encephalomyelitis • Spreads from CNS throughout the PNS especially to highly innervated areas • Progression to generalized nervous system failure and death

36. Rabies • Rabies is a uniformly fatal disease once clinical symptoms manifest • Presents with 1 of 2 clinical forms • Encephalitic (furious) rabies • 80-85% • Hydrophobia, pharyngeal spasm, hyperactivity • Paralysis, coma and death • Paralytic form • Far less common

37. Rabies • 5 clinical stages: • 1) Incubation - Ranges from 10d to 1yr (avg 20-60 days) • 2) Prodrome - Occurs 2-10d post-exposure last <2wks - Nonspecific flu-like illness • 3) Acute Neurologic Syndrome - 2-7days after prodrome onset - Dysarthria, dysphagia, salivation, diplopia, vertigo, nystagmus, agitation, hallucinations, hydrophobia, hyperative DTR, nuchal rigidity • 4) Coma - 7-10 days after neuro symptoms - Prolonged apnea and generalized flaccid paralysis • 5) Death

38. Rabies • Prodrome: • Sounds like all the other viral prodromes? • If the patient has sustained a bite, are there any clues to dx? CLUE: Tingling at the bite over first few days

39. Rabies • Questions • Saliva contact? • Skin breakdown? • Provoked or unprovoked attack? • Wild vs domestic animal? • All suspicious warrant a call to the MOH on-call 264-5615 • Immediately if scratch or bite to head • Urgently in all other cases • Follow-up is with MOH or the clinical disease unit during the day

40. Rabies • Preexposure prophylaxis: • Who gets this? • Travel to area where dog rabies is endemic • Likelihood of being in contact with virus or vectors