Ecology of Hantavirus in Western Paraguay

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Ecology of Hantavirus in Western Paraguay

• Dr. Christopher J. Yahnke
• Department of Biology
• University of Wisconsin Stevens Point

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Chacoan Peccary (Catagonus wagneri)
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December 1995, Colonia Menno, western Paraguay
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Project Objectives

• What is the prevalence of hantavirus antibody in
  wild rodents?
• Which rodent species carry the virus?
• What is the population biology of the primary
  reservoir?
• How do small mammals partition microhabitats?
• What are the habitat associations of the primary
  reservoir?

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Temperature (C)
Rainfall (mm)
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Northwest of Mcal. Estigarribia along transchaco
Mennonite Colonies of central Paraguayan chaco
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Species Total sampled Seropositive Akodon
toba 57 0 Andalgalomys pearsoni 12 0 Bolomys
lasiurus 68 0 Calomys callosus 27 0 Calomys
laucha 209 25 Calomys musculinus 126 0 Grao
mys griseoflavus 106 0 Holochilus
chacarius 10 0 Oligoryzomys chacoensis 31 0
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Vesper mouse (Calomys laucha)
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Number of Captures
Akodon azarae
Akodon toba
Bolomys lasiurus
Calomys callosus
Calomys laucha
Andalgalomys pearsoni
Calomys musculinus
Cavia aperea
Graomys griseoflavus
Holochilus chacarius
Oligoryzomys chacoensis
Gracilinanus agilis
Thylamys pusilla
Monodelphis domestica
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Percent trap success (all rodents)
Rainfall (mm)
one seropositive Calomys laucha
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Prevalence (per cent)
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Percent Calomys laucha seropositive
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Conclusions

• Calomys laucha is the primary reservoir of
  hantavirus in the central Paraguayan chaco.
• Populations of C. laucha are highest during the
  dry season months (June - August).
• Seroprevalence is highest during the dry season.
• Calomys laucha is most common in sorghum habitats
  and uncommon in native forests.

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Data from Chu et al. 2003 The complex ecology of
Hantavirus in Paraguay
Akodon azarae 1/11 (9.1) Akodon
montensis 11/133 (8.3) Bibimys chacoensis 1/5
(20) Graomys griseoflavus 3/70 (4.3) Holochilus
chacarius 3/45 (6.7) Nectomys squamipes 2/14
(14.3) Oligoryzomys chacoensis 1/6
(16.7) Oligoryzomys fornesi 1/13
(7.7) Oligoryzomys nigripes 2/34 (5.9)
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Simplified hypothetical model of interactions
among ecosystem components within disease-endemic
areas for rodent-borne zoonotic disease.
Left-hand side of model demonstrates potential
use of remote sensors (satellites) for predicting
relative risk for human disease.
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Vegetation and Temperature Condition Index (VT)
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Vegetation and Temperature Condition Index (VT)
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Disease ecology in north central Chile
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Map from Mills and Childs, 1998
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Yates et al. 2002. The Ecology and Evolutionary
History of an Emergent Disease Hantavirus
Pulmonary Syndrome. BioScience Vol. 52, No. 11,
pp. 989998.
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Chuckles the Prairie Dog
Natural reservoir of monkeypox virus is African
squirrels.
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Congo Rope Squirrel ( Funisciurus congicus)
Rope squirrels Funisciurus sp. ?? Sun squirrels
Heliosciurus sp. ??