Vector-Borne Infections

1. Vector-Borne Infections Neelay Kothari IHA Infectious Diseases August 30th, 2017

2. Disclosures I have no financial or other conflicts of interest to disclose.

3. Objectives • Definitions • Clinical Approach • Epidemiology • Diagnosis • Treatment • Prevention

4. Zoonoses - Definition • Nonhuman vertebrate reservoir • Transmission directly to humans • From animal • From products derived from the host • Via arthropod intermediate • Recognized infectious syndrome in susceptible hosts

5. Zoonoses - Definition • Nonhuman vertebrate reservoir • Transmission directly to humans • From animal • From products derived from the host • Via arthropod intermediate (VECTOR-BORNE) • Recognized infectious syndrome in susceptible hosts

6. Vectors • Living organism that can transmit infectious diseases between humans or from animals to humans • Examples • Mosquitos • Ticks • Sandflies • Triatome bugs • Tsetse flies • Fleas • Black flies • Aquatic snails

7. Clinical importance • Account for 17% of all infectious diseases • 1 billion annual cases globally • 1 million deaths annually globally

8. Ever-changing spectrum • Global travel and trade • Urbanization • Agricultural practices • Climate change • Water and sanitation access

9. Clinical approach: history • Geography • Season of year • Activities • Potential vector exposures • Clinical syndromes • Incubation period

10. Clinical approach: classification • By vector • By organism • By clinical syndrome • By geographical distribution

11. Case 1 60 year old cattle farmer from Tennessee Presents in June with Fever, abdominal pain, nausea, SEVERE frontal headache for 3.7 hours T 39.4, HR 104 WBC 10.3K, creatinine 1.4, sodium 128 Recent ticks on his pet dogs

12. Case 1 • Which of the following is most likely? • Influenza A • Lyme disease • Rocky mountain spotted fever • Babesiosis

13. Case 1 • Which of the following is most likely? • Influenza A • Lyme disease • Rocky mountain spotted fever • Babesiosis

14. Tick-borne infections (United States) • Uncommon Infections • STARI (Southern tick-associated rash illness) • Tickbornerelapsing fever • Tularemia • Powassan disease • Heartland virus • Bourbon virus • Borreliamayonii • Borreliamiyamotoi • Colorado tick fever • Rickettsia parkeri rickettsiosis • 364D rickettsiosis • Common Infections • Lyme disease • Spotted Fever Rickettsiosis • Anaplasmosis • Ehrlichiosis • Babesiosis

15. Tick appearance

16. Rocky Mountain Spotted Fever • Etiology: Rickettsia rickettsii (gram-negative obligate intracellular organism) • Ticks: • American dog tick (Dermacentorvariabilis) • Rocky mountain wood tick (Dermacentorandersoni) • Brown dog tick (Rhipicephalussanguineus)

17. Rocky Mountain Spotted Fever: Epidemiology

18. Rocky Mountain Spotted Fever: Clinical presentation • Incubation 2-14 days (most commonly 5-7 days) • Early – nonspecific (fever, headache, myalgias, arthralgias, nausea, abdominal pain) • Rash • Initially uncommon (14% at day 1 of symptoms) • 88-90% will develop, usually between days 3-5 • Blanching erythematous rash with macules, becomes petechial • Usually starts on ankles and wrists, and spreads proximally

19. Rocky mountain spotted fever • Diagnosis • Characteristic signs and symptoms with epidemiologic history • Serology • Antibodies appear 7-10 days after onset of symptoms • Acute and convalescent serologies • Skin biopsy • Treatment • Early treatment is key • Doxycycline • Chloramphenicol is alternative • Duration: at least 3 days after fever resolution (usually 7-14 days) • Mortality • Untreated: 20-80% in preantibiotic era • 0.7% in 2007

20. Case 1: Key Points • RMSF is potentially fatal if not treated in timely manner • Early recognition is key (i.e. before onset of rash) • Look to animal health / exposures as potential clues to diagnosis

21. case 2 • 19 year old male presenting in July 2015 • Fever to 101, sweats, myalgias, headache x 4 days • Blotchy rash • Recent travel to Western Upper Peninsula and hiking west of Kalamazoo, with removal of ticks • No recalled tick bites • Lyme ELISA positive, Western Blot IgM positive, IgG negative

22. case 2 • Treatment for this patient? • (A) No treatment • (B) Doxycycline • (C) Ceftriaxone • (D) Oseltamivir

23. case 2 • Treatment for this patient? • (A) No treatment • (B) Doxycycline • (C) Ceftriaxone • (D) Oseltamivir

24. Lyme disease • Most common tick-borne infection in United States • Estimated 300,000 annual cases • Increasing in incidence • Majority of US cases caused by spirochete Borreliaburgdorferi(other borrelia species in various parts of the world) • Transmitted by blacklegged ticks (nymph stage) • Ixodesscapularis (northeast, mid-atlantic, north-central US) • Ixodespacificus (west coast)

25. Lyme disease – expanding geography

26. Lyme disease – expanding geography

27. Lyme disease – expanding geography

28. Lyme disease – expanding geography

29. Lyme disease – expanding geography

30. Lyme disease – expanding geography

31. Lyme disease – expanding geography

32. Lyme disease – expanding geography

33. Lyme disease – expanding geography

34. Lyme disease – expanding geography

35. Lyme disease – expanding geography

36. Lyme disease – expanding geography

37. Lyme disease – expanding geography

38. Lyme disease – expanding geography

39. Lyme disease – expanding geography

40. Lyme disease in Michigan • Washtenaw County 2016 • 4 cases acquired within county • 13 cases acquired elsewhere

41. Lyme Disease cases by month – United States 2001-2015

42. Tick Life-Cycle

43. Lyme disease: transmission • Usually from nymph stage of ticks (~2 mm in size) • Attachment for 36-48 hours at least required for transmission to occur • Usually spring to summer months

44. Early lyme disease • Early Localized Disease (range 3-30 days after bite, usually 7-14 days) • Erythema migrans rash • Seen in up to 80% of patients • Not generally painful • Expand over days to weeks • Constitutional symptoms (headache, fatigue, myalgias, fevers) • Early Disseminated Disease (weeks to months later) • Neurologic: lymphocytic meningitis, cranial nerve palsy, radiculopathy, neuropathy, mononeuritis multiplex • Carditis: heart block, myopericarditis

45. Late disseminated lyme disease • Typically occurs months to years later • Arthritis • Large joints, often knee • Intermittent or persistent • Neurologic manifestations • Peripheral neuropathy • Encephalopathy or encephalomyelitis

46. Lyme Disease Treatment • Early Disease • Doxycycline 100 mg bid x 10-21 days • Amoxicillin 500 mg tid x 14-21 days • Cefuroxime 500 mg bid x 14-21 days

47. case 3 • 35 year old male • Recent hiking in Wisconsin in Lyme-endemic region • Now with rash, mild fever and achiness

48. case 3 • How should this patient be managed? • (A) Check Lyme ELISA and Western Blot, treat if positive • (B) Skin biopsy with PCR for Lyme disease • (C) Doxycycline • (D) Cephalexin

49. case 3 • How should this patient be managed? • (A) Check Lyme ELISA and Western Blot, treat if positive • (B) Skin biopsy with PCR for Lyme disease • (C) Doxycycline • (D) Cephalexin

50. Lyme Testing • ELISA followed by Western Blot • IgM: seen within 1-2 weeks of EM rash • IgG: seen within 2-6 weeks of EM rash