Trypanosoma cruzi in the Southeastern United States

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Trypanosoma cruzi in the Southeastern United
States

• Dr. Christopher Hall
• Dept. of Biology, Berry College

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T. cruzi

• Etiologic agent for Chagas Disease
• 13 - 20 million infected throughout Latin America
• Approx. 25 will develop symptoms
• 14,000 annual deaths
• Economic impact of morbidity?

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T. cruzi Life Cycle
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Latin American Cycle

• Divided into geographic foci.
• Vector population
• Parasite strain
• Type I vs. II
• Reservoir hosts
• Land use

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R. prolixus
Panstrongylus spp.
T. infestans
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T. cruzi in North America

• T. cruzi is endemic across the southern United
  States
• Prevalence of infection in raccoons in the
  southeast 15 - 70
• Type I and Type II strains.

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Reservoir Host Survey

• Cumberland Island is Georgias southernmost
  barrier island.
• Prominent recreational destination.
• Designated as a National Seashore in 1972.
• The ecological system on the island is isolated
  with a number of synanthropic mammals present.

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Species Sampled Procyon lotor
(Raccoon) Didelphis virginiana (Opossum) Sus
scrofa (Feral Swine) Scalopus aquaticus (Eastern
Mole) Eptesicus fuscus (Brown Bat) Lasiurus
seminolus (Seminole Bat) Tadarida brasiliensis
(Free-Tailed Bat) Peromyscus gossypinus (Cotton
Mouse)
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Vectors

• In the U.S. two of the dominant vectors are T.
  sanguisuga, T. gerstaeckeri

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Where we find T. sanguisuga

• High densities normally found in old chicken
  houses near a wooded area

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Sylvatic, peri-domestic, and domestic sites
Sewanee, Tennessee
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• Despite prevalence, endemically acquired
  infections rare in the U.S.
• 1955 Two infants in Texas
• 1984 Elderly woman in central California
• 1998 Infant in central Tennessee
• 2006 Elderly woman in Louisiana
• Type I strain

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Serological Surveys

• 1972 3883 Sera from Georgia tested for T. cruzi
• 54 from primary myocardial disease patients
• 2 light positives
• Trappers Survey 2002-04
• Georgia Trappers Association Meetings
• 56 trappers submitted samples

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• Negative for
• WEE
• WNV
• LAC
• E. chaffeensis
• Coxiella burnetti
• R. typhi

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• Positive for
• EEE (1)
• SLE (2)
• LAC (6)
• R. rickettsii (12 _at_ 1/128, 30 _at_ 1/64).
• Sarcocystis neurona (4)
• T. gondii (29)
• T. cruzi (?)
• Negative?
• 23 for at least one T. c. antigen

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Endemic Type IIa of low virulence
Growth dynamics of a Type I (BS) and a Type IIa
(LI)
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Vertical Transmission
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So why be concerned?

• 97 increase in Hispanic immigrant population
  between 1990 and 2000.
• 12,735,263
• 8 of the top 20 countries of origin for
  immigrants to the U. S. are endemic for T. cruzi.
• 5 of the 8 states with the greatest increase in
  Hispanic population are in the southeast.

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• Estimated number of T. cruzi seropositive donors
• 1/9900 (1996)
• 1/5400 (1998)
• 1/2000 (2006)
• Estimated 25,000 100,000 infected immigrants in
  the U.S. (2002)

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Result

• 10 cases of transmission via blood or organ
  donation since 2002.
• FDA has approved the Ortho-Clinical Diagnostics
  assay approved for screening U.S. blood supply.

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Other Concerns

• Better Vectors?
• More virulent strains introduced into the
  existing sylvatic cycle.
• T. sanguisuga has been experimentally infected
  with the virulent Brazil strain.
• The good news?
• Sylvatic population may be protected.

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Summary

• The endemic cycle isnt likely to cause
  widespread pathology in humans.
• Situations that bring sylvatic reservoirs and
  vectors into domestic sites are of concern.
• The introduction of more virulent strains and
  more competent vectors may upset the ecological
  balance of the endemic system.

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• Acknowledgements
• North Carolina State Laboratory of Public Health
• Arbovirus, Ehrlichia, and Rickettsial serology
• Dr. David Lindsey, Va. Tech
• Sarcocystis and Toxoplasma testing
• Dr. Rick Tarleton, UGA, CTEGD
• Frank Steurer, CDC
• T. cruzi serology

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Questions?
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Model for Horizontal Transmission
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Horizontal Transmission Model with Differential
Behavior Factor
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Model Modifications for Vertical Transmission