Ticks, Mites and Associated Pathogens Overview: Characteristics of the subclass Acari (ticks and mites) Metastigmatid mi

1. Ticks, Mites and Associated Pathogens • Overview: • Characteristics of the subclass Acari (ticks and mites) • Metastigmatid mites = ticks • Ticks and tick-borne pathogens • All other mites…. • Mites and mite-borne pathogens

2. Ticks and Mites (Subclass Acari) • 1. Class Arachnida (Also includes spiders and scorpions • 2. Characteristics of Acari (mites and ticks): • a. sac-like, unsegmented body • b. highly specialized mouthparts, capitulum w/ hypostome • c. phytophagous, predatory, parasitic • d. larvae 6 legs, nymph & adult 8 legs • e. 4-stage life cycle, egg-larva-nymph-adult

3. Ticks and Mites - Classification Class Arachnida Subclass Acari Order Ixodida (= Metastigmata) (ticks) Order Mesostigmata (free-living, predaceous, and parasitic mites) Order Prostigmata (chiggers, follicle mites) Order Astigmata (house dust, storage & scabies mites)

4. Ticks - Classification Class Arachnida Ticks (3 families): Ixodidae Argasidae Nuttalliellidae Subclass Acari Order Superorder Parasitiformes Source: http://tolweb.org/tree/phylogeny.html

5. Mites - Classification Class Arachnida Subclass Acari Mesostigmatid Mites Superorder Parasitiformes Order Source: http://tolweb.org/tree/phylogeny.html

6. Mites – Classification (2) Superorder Acariformes Prostigmatid and Astigmatid Mites Class Arachnida Subclass Acari Source: http://tolweb.org/tree/phylogeny.html

7. Ticks and Mites - Classification • Recent validation of Acari suborders (ticks are ticks and mites are mites) • Recent reorganization within the ticks J. S. H. Klompen, William C. Black IV, James E. Keirans, and Douglas E. Norris. 2000. Systematics and Biogeography of Hard Ticks, a Total Evidence Approach.Cladistics16, 79–102. Ivan G. Horak, Jean-Louis Camicas and James E. Keirans. 2002. The Argasidae, Ixodidae and Nuttalliellidae (Acari: Ixodida): a world list of valid tick names.Experimental and Applied Acarology 28: 27–54.

9. TICKS MITES

10. TICKS • Characteristics of Ixodida (ticks) - approx. 900 species • a. largest of acarines - larger than mites • b. toothed hypostome • c. Haller's organ (sensory pit on tarsi of first pair of legs) • d. absence of claws on palps • e. evolved as parasites of reptiles, adaptation to mammals associated with general reduction in body size • Tick Families:Ixodidae - Hard Ticks, Argasidae – Soft Ticks, Nuttalliellidae - rare, S. Africa (single species)

11. Hard tick (Family Ixodidae) Soft tick (Family Argasidae)

12. Family IxodidaeHard Ticks (approx. 683 species, 12 genera) • Features: • a. sexual dimorphism, male - enlarged scutum, female - shield • b. mouthparts (capitulum) visible dorsally • c. feed only once during each stage, often diurnal, males show little size increase • d. range parasites, questing from vegetation, one large egg batch

13. Male hard tick Female hard tick

14. Typical Life History of Hard Ticks • (most three-host): • a. One-Host: Rhipicephalus (Boophilus) annulatus (Texas Cattle Fever Tick), all stages on same host, but leave host to molt, control using pasture rotation • b. Three-Host: Dermacentor variabilis (American Dog Tick), each stage uses a different host - larva on small rodents, nymph on larger mammal, adult on another large mammal. Other three host: Rhipicephalus sanguineus (Brown Dog Tick) Amblyomma americanum (Lone Star Tick)

15. Description of medically-important hard ticks: GenusApprox. # SpeciesDistribution World U.S. Amblyomma 100 7 worldwide, mostly tropical Dermacentor 31 7 worldwide Hyalomma 30 0 Africa, Asia Nosomma 1 0 India, SE Asia Rhipicephalus 68 3 Ethiopian / tropicopolitan (includes Boophilus) Haemaphysalis 155 2 worldwide Ixodes 217 40 worldwide Margaropus 2 0 southern, east Africa Bothriocroton 5 0 Austrailia

16. Genus Ixodes:Largest genus of hard ticks • Ixodes ricinus/persulcatus complex - Lyme Disease, HGE • I. ricinus (European Sheep tick) through Europe, Turkey, Iran • I. persulcatus (Taiga tick) Eurasian • I. scapularis (Black-legged tick) eastern US • I. pacificus (Western Black-legged tick) western US. • I. holocyclus Australia (tick paralysis) • I. rubicundus (Karoo tick) South Africa

17. Genus Haemaphysalis: Small, both sexes similar, important in enzootic cycles • H. leporispalustris (Rabbit tick) western hemisphere distribution (important maintenance vector for tularemia and RMSF) • Genus Hyalomma: Large unornamented ticks • H. marginatum Russian states, southern • Europe (Crimean-Congo hemorrhagic fever)

18. Genus Rhipicephalus: African origin, but several species worldwide in the tropics (now includes previous species of Boophilus, non-ornamented, one-host ticks) • R. sanguineus (Brown Dog tick) cosmopolitan • distribution (RMSF, boutonneuse fever) • R. (Boophilus) annulatus(Cattle Fever tick) southern US, Mexico (Texas Cattle fever, field rotation for control) • R. (Boophilus) microplus(Southern cattle tick) Australia, Mexico, S. America

19. Genus Dermacentor: Ornate ticks • D. variabilis (American dog tick) eastern US, Canada, Mexico (tularemia, RMSF) • D. andersoni (Rocky Mountain wood tick) western North America (tularemia, RMSF, Colorado tick fever) • D. albipictus (Winter tick) across Canada • D. occidentalis (Pacific coast tick) Oregon, California

20. Genus Amblyomma: Large ornate ticks • A. americanum (Lone Star tick) central/eastern US - S. American (RMSF, tularemia) • A. cajennense (Cayenne tick) Texas, S. America, Caribbean • A. hebraeum (Bont tick) S. Africa

21. Family ArgasidaeSoft Ticks • (183 species, 4 genera) • Features: • a. slight sexual dimorphism, only slight • swelling from feeding • b. scutum absent • c. capitulum not visible dorsally • d. palpi leg-like and flexible • e. intermittant "rapid" feeder, nocturnal • f. sometime several nymphal instars, some • non-feeding larvae • g. lair parasites, several egg batches, • dry adverse environments

22. Hard tick (Family Ixodidae) Soft tick (Family Argasidae)

23. Typical life history of soft ticks: • a. Many-host cycle. Often one larval host and several nymphal and adult hosts. Adult female lays eggs after each feeding • Argas persicus (Fowl Tick) chicken houses, bird nests, cosmopolitan • Ornithodoros moubata (African Relapsing Fever Tick) feeds on sleeping humans, southern Africa • Otobius megnini (Spinose Ear Tick) adult non-feeding, nymph problem

24. Description of medically-important soft ticks: GenusApprox. # speciesDistribution Argas55 worldwide Ornithodoros38 worldwide Otobius3 western hemisphere Carios84worldwide

25. Genus Argas: most nocturnal bird-associated • A. persicus (Fowl tick) cosmopolitan (economic importance, painful bite) • A. arboreus east, S. Africa (arbovirus vector)

26. Genus Ornithodoros: Reservoirs and vectors of relapsing fever • O. moubata (African Relapsing Fever tick) S. Africa (species complex) numerous species • Genus Otobius: Adults do not feed • O. megnini (Spinose ear tick) western hemisphere, Africa, India (nymphal infestations in ears)

27. Tick Sampling a. observation on hosts and premises b. Dragging/flagging c. CO2 - baited traps Tick Control a. Natural predators b. Repellents/toxicants for human use I. DEET (apply to skin) II. Pyrethroids (apply to clothing)

28. Cultural/mechanical control • I.remove harborage for hosts/ticks • II. destroy hosts • III. pasture rotation (one-host only) • Resistant livestock • Anti-tick vaccine • Chemical control on animal host, or • acaricide in habitat

29. AVOIDING TICKS • Wear light-colored clothing to allow you to see ticks that are crawling on your clothing. • Tuck your pants legs into your socks so that ticks cannot crawl up the inside of your pants legs. • Apply repellants to discourage tick attachment. Repellents containing permethrin can be sprayed on boots and clothing, and will last for several days. Repellents containing DEET (n, n-diethyl-m-toluamide) can be applied to the skin, but will last only a few hours before reapplication is necessary. Use DEET with caution on children. Application of large amounts of DEET on children has been associated with adverse reactions.

30. AVOIDING TICKS - II • Conduct a body check upon return from potentially tick-infested areas by searching your entire body for ticks. Use a hand-held or full-length mirror to view all parts of your body. Remove any tick you find on your body. • Parents should check their children for ticks, especially in the hair, when returning from potentially tick-infested areas. Additionally, ticks may be carried into the household on clothing and pets. Both should be examined carefully.

31. Tick Removal: 1. Use fine-tipped tweezers or shield your fingers with a tissue, paper towel, or rubber gloves. When possible, persons should avoid removing ticks with bare hands. 2.Grasp the tick as close to the skin surface as possible and pull upward with steady, even pressure. Do not twist or jerk the tick; this may cause the mouthparts to break off and remain in the skin. Removal of an embedded tick using fine-tipped tweezers.

32. 3. Do not squeeze, crush, or puncture the body of the tick because its fluids (saliva, body fluids, gut contents) may contain infectious organisms. 4. After removing the tick, thoroughly disinfect the bite site and wash your hands with soap and water. 5. Save the tick for identification in case you become ill. This may help your doctor make an accurate diagnosis. Place the tick in a plastic bag and put it in your freezer. Write the date of the bite on a piece of paper with a pencil and place it in the bag.

35. Photograph copyright 2001 Steve Barker Haemaphysalis bremnerimouthparts, showing toothed, sawlike hypostome.

36. Photograph copyright 2001 Steve Barker Otobius megnini

37. Medical Importance of Ticks • 1. Dermatosis - inflammation, itching , swelling at site of bite • 2. Exsanguination - anemia can result from heavy infestation • 3. Otoacariasis - auditory canal infestation, poss. secondary infection • 4. Predispose to myiasis and infection • 5. Tick paralysis (envenomization) • 6. Pathogen transmission (virus, rickettsia, bacteria, spirochaete, protozoa, filarial worms)

38. Factors Accounting for High Vector Potential of Ticks 1. Persistent hematophagous feeders 2. Relatively slow feeding time allows time for pathogen transfer 3. Typically have a wide host range 4. Longevity increases chances of acquiring and transmitting a pathogen 5. Transovarial transmission of some pathogens 6. Few natural enemies, highly sclerotized (resistant to environmental stress) 7. High reproductive potential - up to 18,000 eggs and parthenogenesis in some species

39. Non-viral Tick-Borne Pathogens • Lyme Disease (Borrelia burgdorferi) • Babesia microti (malaria-like) • Ehrlichia species • Relapsing fever (Borrelia species) • Tularemia (Francisella tularensis) • RMSF (Rickettsia rickettsii) • Tick typhus (Rickettsia sp.) • Heartwater (Cowdria ruminantium) • Anaplasmosis (Anaplasma sp.)

40. Some Tick-Borne Pathogens • Human monocytic ehrlichiosis (HME), caused by Ehrlichia chaffeensis a new monocytotropic ehrlichia, was discovered in 1986 and human granulocytic ehrlichiosis (HGE), caused by the HGE agent (newly named Anaplasma phagocytophilum), a new granulocytotropic ehrlichia, was discovered in 1994. • In 1999 another granulocytotropic ehrlichia, E. ewingii which was previously known as a canine pathogen has been recognized as human pathogen. E. sennetsu (renamed to Neorickettsia sennetsu) is another monocytotropic Ehrlichia sp. and the first human pathogen discovered in Japan in the 1950’s and recently found in Malaysia.

41. This phylogram is constructed based on 16S rRNA sequences of these species. Nomenclature has been changed from original names based on 16S rRNA sequences which divided them into four genera groups. Family Anaplasmataceae now contains four genera: Ehrlichia, Anaplasma, Neorickettsia, and Wolbachia.

42. Ehrlichiosis and Anaplasmosis • Small gram-negative bacteria that grow in membrane-bound vacuoles in leukocytes or platelets • Typically 1-3 um cocci • Different species of Ehrlichia infect different types of host cells • Not all species transmitted by arthropods • HME (human monocytic ehrlichiosis), E. chaffeensis • HGE (human granulocytic ehrlichiosis), (A. phagocytophila) • HGE overlap with Lyme disease - both transmitted by Ix. scapularis complex members in US

43. Ehrlichia chaffeensis is principally transmitted by the lone star tick (Amblyomma americanum). White-tailed deer are a major host of lone star ticks and appear to represent one natural reservoir for E. chaffeensis. Antibody to E. chaffeensis has been found throughout deer populations in the southeastern and midwestern United States, and the organism has been cultured from deer blood. (CDC)

44. Cases of HME are predominantly found in the South and south-central regions where the suspect vector, the Lone Star tick (Amblyomma americanum) is present. Amblyomma americanum Lonestar tick Associated with E. chaffeensis transmission (HME)

45. Average annual incidence of reported human monocytic ehrlichiosis (HME) by county, using 1995 population census data.

46. The HGE agent has been associated with the blacklegged tick (Ixodes scapularis) in the northeastern and upper midwestern United States. The western blacklegged tick (Ixodes pacificus) is a vector in northern California. Ixodes ricinus has been shown to be a vector of A. phagocytophila in Europe. Deer, elk, and wild rodents are likely reservoirs.

47. Ixodes pacificus - western black-legged tick Cases of HGE have been reported primarily in the Northeast and Midwest regions and are associated with the bite of deer ticks (Ixodes scapularis). A few cases on the Pacific coast are associated with the related species, Ixodes pacificus. Ixodes scapularis - black-legged deer tick

48. Average annual incidence of reported human granulocytic ehrlichiosis (HGE) by county, using 1995 population census data.

49. Distribution of the Tick Vectors of Ehrlichia and Anaplasma in the United States

50. Ehrlichiosis - Epidemiology • During 1986 to 1997, health departments and other diagnostic laboratories reported over 1200 cases of human ehrlichiosis to CDC. • Approximately two-thirds were cases of HME. CDC compiles the number of cases reported by the state health departments. • Ehrlichiosis is a nationally notifiable disease; however, not all state health departments have reported cases of ehrlichiosis to CDC.