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Emerging Tick-borne Diseases of the Southern United States

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Emerging Tick-borne Diseases of the Southern United States William H. Dees1, Richard G. Robbins2 and Jerome Goddard3 1McNeese State University, Lake Charles, LA – PowerPoint PPT presentation

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Title: Emerging Tick-borne Diseases of the Southern United States


1
Emerging Tick-borne Diseases of theSouthern
United States
  • William H. Dees1, Richard G. Robbins2
  • and Jerome Goddard3
  • 1McNeese State University, Lake Charles, LA
  • 2Armed Forces Pest Management Board, Washington,
    DC
  • 3Mississippi State Department of Health, Jackson,
    MS

2
Abstract
  • A review of the scientific literature published
    over the last ten years indicates that at least
    nine tick-borne diseases occur in the southern
    United States. A tenth disease, Q fever caused
    Coxiella burnetii, is not thought to be
    transmitted by ticks in the American South. All
    ten pathogens are briefly described herein,
    together with their principal vectors. This
    presentation was originally given in poster form
    at the 35th Annual Conference of the Society for
    Vector Ecology, Coeur dAlene, Idaho, 5-8 October
    2003.

3
States of the Southern United States
4
Tick-borne Diseases of the South
  • Babesiosis
  • Babesia microti
  • Other Babesia spp. possibly associated with human
    infection continue to be discovered
  • Borreliosis
  • Borrelia burgdorferi (Lyme Disease - LD)
  • B. lonestari (Southern Tick-Associated Rash
    Illness - STARI)
  • B. turicatae (Tick-Borne Relapsing Fever - TBRF)
  • Other Borrelia spp./strains possibly associated
    with human infection continue to be discovered
  • Ehrlichiosis
  • Ehrlichia chaffeensis
  • Human Monocytic Ehrlichiosis (HME)
  • E. ewingii/others
  • Human disease/nonspecific

5
  • Anaplasma phagocytophilum
  • Human Granulocytic Ehrlichiosis (HGE)
  • Q Fever
  • Coxiella burnetii
  • Rickettsiosis
  • Rickettsia rickettsii (RMSF)
  • Other Rickettsia spp. possibly associated with
    human infection continue to be discovered
  • Tularemia
  • Francisella tularensis
  • Affliction - Tick Paralysis

6
  • Babesiosis
  • Protozoan parasite of red blood cells
  • Babesia microti has been reported in Missouri
    (edge of Southern U.S.).
  • Most infections are asymptomatic, although
    babesiois is a potentially fatal disease.
  • Vector
  • Ixodes scapularis
  • Related disease agents
  • Babesia canis in dogs Southern U.S.
  • Babesia gibsoni in dogs Southern U.S.
  • Babesia equi in horses FL

CDC
CDC
7
  • Lyme Disease (LD)
  • Bacterium
  • Borrelia burgdorferi
  • Most cases reported from Northeast, Mid-Atlantic
    and North-Central U.S., although additional
    genetically varied strains and tick vectors may
    occur in the South.
  • Has a high potential transmission rate.
  • Principal vector
  • Ixodes scapularis
  • Secondary or potential vectors include
  • Other Ixodes spp.
  • Amblyomma spp.
  • Dermacentor spp. (OK)

CDC
CDC
8
Figure 1. Lyme Disease in TX and OKfrom MMWR1,
CDC21MMWR Morbidity and Mortality Weekly
Report2CDC Centers for Disease Control and
Prevention
9
  • Figure 1 shows fluctuations in the numbers of
    LD cases over the last ten years. The number of
    cases in TX ranged from 32 to 97 per year. OK
    reported a decrease in the number of cases.
    False-positive test results and over-diagnosis
    may have resulted in the increased numbers from
    1994-1997. Since 1998, only a few cases (lt13)
    have been reported in OK.

10
Figure 2. Lyme Disease in Southeastern U.S.from
MMWR1, CDC21MMWR Morbidity and Mortality
Weekly Report2CDC Centers for Disease Control
and Prevention
11
  • Figure 2 shows fluctuations in the numbers
    of LD cases over the last ten years. Last years
    (2002) data indicate an increase in LD cases.
    This increase is due to the unusually large
    number of cases reported from NC and FL. NC
    reported 137 cases, which is almost half the
    cases shown for 2002 and is over three times the
    number of cases reported by NC in 2001. FL
    reported 81 cases, twice the number reported in
    2001. In light of the fact that immature Ixodes
    scapularis in the Southeast frequently feed on
    lizards and skinks, it is suspected that many of
    these cases are actually imports from other areas
    of the country, especially the Northeast.

12
  • Southern Tick-Associated Rash Illness (STARI)
  • Bacterium
  • Borrelia lonestari (?)
  • Shows symptoms similar to Lyme disease.
  • B. lonestari and closely related Borrelia species
    are present in nature in several southern states.
  • Vector
  • Amblyomma americanum
  • found throughout the South
  • Overall, the number one arthropod-borne disease
    of humans in the U.S. is Lyme disease, caused by
    Borrelia burgdorferi. However, this may not be
    the case in the southern states, where Borrelia
    lonestari and/or another undescribed
    Borrelia-like spirochete may cause borreliosis.

CDC
13
Tick-borne Relapsing Fever
  • Bacterium
  • Borrelia turicatae
  • Most cases reported from the Midwest and western
    U.S.
  • Transmission by bite or coxal fluid.
  • Vector
  • Ornithodoros turicata (TX)

ForestryImages
James L. Occi
14
  • Ehrlichiosis
  • Caused by at least three different agents.
  • Recognized in U.S. since mid-1980s.
  • Presents clinical features similar to Rocky
    Mountain spotted fever.
  • Became notifiable by Centers for Disease Control
    and Prevention (CDC) in 1999.
  • Bacterium
  • Ehrlichia chaffeensis
  • Described in 1987.
  • Causes human monocytic ehrlichiosis (HME).
  • States with the highest prevalence in the
    southern U.S. are AR, OK and TN.

15
  • Principal vector
  • Amblyomma americanum
  • Secondary vector
  • Dermacentor variabilis

CDC
CDC
16
  • Bacterium
  • Ehrlichia ewingii
  • Causes nonspecific human disease.
  • Thus far mostly reported in immuno-compromised
    individuals.
  • Vectors
  • Amblyomma americanum (also
    suspect Dermacentor variabilis
    and Rhipicephalus sanguineus (?))

CDC
17
  • Bacterium
  • Anaplasma phagocytophilum
  • Described in 1994.
  • Causes human granulocytic ehrlichiosis (HGE).
  • Vector
  • Ixodes scapularis
  • Potential vector
  • Dermacentor variabilis

CDC
CDC
18
  • Q Fever
  • Rickettsia
  • Coxiella burnetii
  • Cosmopolitan zoonotic disease, reported from
    various areas throughout the U.S.
  • Primary reservoirs are cattle, sheep and goats.
  • Typically acquired through inhalation of
    contaminated dust or debris.
  • Ticks not major source of human infection in U.S.
  • Recently reported in GA and TN however, unlikely
    that ticks were involved.
  • Acute febrile disease. There is considerable
    variation in severity and duration. Some
    infections may present as fever of unknown
    origin (FUO).
  • Declared a notifiable disease by Centers for
    Disease Control and Prevention in 1999 some
    states consider it not notifiable.

19
  • Rocky Mountain Spotted Fever (RMSF)
  • Rickettsia
  • Rickettsia rickettsii
  • Most common fatal tick-borne disease in the U.S.
  • Characterized by fever, myalgia, headache and
    rash.
  • Despite name, RMSF is a disease of the South.
    Historically, NC and OK have accounted for about
    a third of all cases. Besides these two states,
    recent data indicate SC, TN and AR have the
    greatest numbers of cases.
  • Seasonal outbreaks parallel activity of tick
    vectors.
  • Delayed diagnosis and treatment are associated
    with increased risk of severe complications and
    death.
  • Therapy should be initiated quickly if RMSF
    suspected, especially in patients presenting with
    fever, rash and history of tick exposure.

20
  • Vector
  • Dermacentor variabilis
  • Other ixodids possibly involved.
  • Other Rickettsia spp. have been detected in
    Amblyomma americanum, A. cajennense, Ixodes
    scapularis, and Rhipicephalus sanguineus.

CDC
21
Figure 3. RMSF in TX and OK from MMWR, CDC
22
  • Figure 3 shows fluctuations in the number of
    RMSF cases in TX and OK. In OK, the number of
    cases ranged from 29 to 62 per year. TX reported
    0-10 cases/year. In Oklahoma, recent studies
    (McQuiston et al. 2000) show the incidence of
    RMSF to be significantly higher in American
    Indians when compared to the overall population
    of that state.

23
Figure 4. RMSF in Southeastern U.S.from MMWR,
CDC
24
  • Figure 4 shows a general increase in RMSF in
    the Southeast. In 2002, NC, SC and AR nearly
    doubled the number of reported cases from the
    previous year. Increasing suburban development
    in many parts of the Southeast may cause larger
    numbers of people to come into contact with
    vector ticks.

25
  • Tularemia
  • Bacterium
  • Francisella tularensis
  • Acute plague-like zoonotic infection with a
    variety of clinical manifestations related to
    route of introduction and virulence of pathogen.
  • Several ways of acquiring infection (food, water,
    aerosol).
  • Natural transmission also occurs via tick bites.
  • Can be fatal if it is not treated with
    appropriate antibiotics.
  • Sporadic cases occur in all states in the U.S.
    In 2000, states with the highest prevalence in
    the southern U.S. were AR (23), OK (11), NC (2),
    TN (1)historically, TN has reported more cases,
    and GA (1).
  • Within the last 2 years, lt25 cases were reported
    in any southern state.
  • Incidence in the U.S. has declined substantially
    over the years. The Centers for Disease Control
    and Prevention removed tularemia as a notifiable
    disease in 1994, but reinstated it effective
    January 1, 2000, because of its potential as a
    bioterrorism agent.

26
  • Vectors
  • Dermacentor variabilis
  • Amblyomma americanum
  • Potential vectors
  • Almost any ixodid tick

CDC
CDC
27
  • Miscellaneous
  • In TX in 2001, Houck et al. reported the first
    evidence of hantavirus-specific RNA (Bayou) from
    an unidentified adult ixodid tick collected from
    a hantavirus-positive cotton rat, Sigmodon
    hispidus.
  • This does not necessarily mean that ticks can
    transmit hantavirus.
  • The third author (J.G.) has found

    an unidentified trypanosome-like
    organism in
    hemolymph of
    Ixodes scapularis.

Suspected trypanosome 1,000X (Photo by JG)
28
  • Affliction - Tick Paralysis
  • Acute, ascending, flaccid motor paralysis caused
    by a toxin in tick saliva.
  • In 2000, tick paralysis was reported in a young
    girl in GA. The tick Dermacentor variabilis was
    found and removed. Within 24 hours, all signs
    and symptoms had fully resolved.
  • The third author (J.G.) has investigated two bona
    fide cases in MS over the past decade.
  • Affects both humans and other animals throughout
    the South.
  • Principal tick species causing paralysis
  • Dermacentor spp.
  • Other ticks known to cause paralysis
  • Ixodes spp.
  • Amblyomma spp.
  • Rhipicephalus spp.

CDC
29
  • Ticks Reported Biting Humans in the Southern U.S.
  • Hard Ticks
  • Amblyomma americanum - lone star tick
  • A. cajennense - Cayenne tick
  • A. imitator - imitator tick
  • A. inornatum
  • A. maculatum - Gulf Coast tick
  • A. tuberculatum - gopher tortoise tick
  • Boophilis annulatus - cattle tick
  • Dermacentor variabilis - American dog tick
  • Haemaphysalis leporispalustris - rabbit tick
  • Ixodes brunneus
  • I. cookei (vector of Powassan virus in NE U.S.)
  • I. dentatus
  • I. scapularis - blacklegged tick
  • Rhipicephalus sanguineus - brown dog tick

30
  • Soft Ticks
  • Argas miniatus - fowl tick
  • Ornithodoros stageri
  • O. turicata - relapsing fever tick
  • Otobius megnini - spinose ear tick

31
Selected References
  • Barbour, AG. 1996. Does Lyme disease occur in the
    South? A survey of emerging tick-borne
    infections in the region. Am J Med Sci 311(1)
    34-40
  • Dworkin MS, PC Shoemaker, CL Fritz, ME Dowell and
    DE Anderson, Jr. 2002. The epidemiology of
    tick-borne relapsing fever in the United States.
    Am J Trop Med Hyg 66(6)753-758
  • Goddard, J. 2002. A ten-year study of tick biting
    in Mississippi Implications for human disease
    transmission. J Agromed 825-32
  • Harrison, BA, BR Engber and CS Apperson. 1996.
    Ticks (AcariIxodida) uncommonly found biting
    humans in North Carolina. J Vector Ecol 22(1)
    6-12
  • Houck, MA, H Qin and HR Roberts. 2001. Hantavirus
    transmission Potential role of ectoparasites.
    Vector Borne Zoonotic Dis 1(1) 75-79
  • McQuiston, JH, RC Holman, AV Groom, SF Kaufman,
    JE Cheek and JE Childs. 2000. Incidence of Rocky
    Mountain spotted fever among American Indians in
    Oklahoma. Public Health Reports 115(5) 469-475
  • McQuiston, JH, CD Paddock, RC Holman and JE
    Childs. 1999. The human ehrlichioses in the
    United States. http//www.cdc.gov/ncidod/eid/vol5n
    o5/ mcquiston.htm
  • Merten HA and LA Durden. 2000. A state-by-state
    survey of ticks recorded from humans in the
    United States. J Vector Ecol 25(1) 102-113

32
  • Morbidity reports and summaries.
    http//www.cdc.gov/mmwr
  • Tick and tick-borne diseases information.
    http//www.cdc.gov
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