• 1

    Parola P, Paddock CD, Raoult D, 2005. Tick-borne rickettsioses around the world: emerging diseases challenging old concepts. Clin Microbiol Rev 18 :719–756.

    • Search Google Scholar
    • Export Citation
  • 2

    Dumler JS, Madigan JE, Pusterla N, Bakken JS, 2007. Ehrlichioses in humans: epidemiology, clinical presentation, diagnosis, and treatment. Clin Infect Dis 45 (Suppl 1):S45–51.

    • Search Google Scholar
    • Export Citation
  • 3

    Ripoll CM, Remondegui CE, Ordonez G, Arazamendi R, Fusaro H, Hyman MJ, Paddock CD, Zaki SR, Olson JG, Santos-Buch CA, 1999. Evidence of rickettsial spotted fever and ehrlichial infections in a subtropical territory of Jujuy, Argentina. Am J Trop Med Hyg 61 :350–354.

    • Search Google Scholar
    • Export Citation
  • 4

    Paddock CD, Fernandez S, Echenique GA, Sumner JW, Reeves WK, Zaki SR, Remondegui CE, 2008. Rocky Mountain spotted fever in Argentina. Am J Trop Med Hyg 78 :687–692.

    • Search Google Scholar
    • Export Citation
  • 5

    de Lemos ER, Alvarenga FB, Cintra ML, Ramos MC, Paddock CD, Ferebee TL, Zaki SR, Ferreira FC, Ravagnani RC, Machado RD, Guimaraes MA, Coura JR, 2001. Spotted fever in Brazil: a seroepidemiological study and description of clinical cases in an endemic area in the state of Sao Paulo. Am J Trop Med Hyg 65 :329–334.

    • Search Google Scholar
    • Export Citation
  • 6

    Galvao MA, Dumler JS, Mafra CL, Calic SB, Chamone CB, Cesarino, Filho G, Olano JP, Walker DH, 2003. Fatal spotted fever rickettsiosis, Minas Gerais, Brazil. Emerg Infect Dis 9 :1402–1405.

    • Search Google Scholar
    • Export Citation
  • 7

    Schoeler GB, Moron C, Richards A, Blair PJ, Olson JG, 2005. Human spotted fever rickettsial infections. Emerg Infect Dis 11 :622–624.

  • 8

    Zavala-Castro JE, Zavala-Velasquez JE, Walker DH, Ruiz EE, Laviada-Molina H, Olano JP, Ruiz-Sosa JA, Small MA, Dzul-Rosado KR, 2006. Fatal human infection with Rickettsia rickettsii, Yucatan, Mexico. Emerg Infect Dis 12 :672–674.

    • Search Google Scholar
    • Export Citation
  • 9

    Zavala-Velazquez JE, Yu XJ, Walker DH, 1996. Unrecognized spotted fever group rickettsiosis masquerading as dengue fever in Mexico. Am J Trop Med Hyg 55 :157–159.

    • Search Google Scholar
    • Export Citation
  • 10

    Estripeaut D, Aramburu MG, Saez-Llorens X, Thompson HA, Dasch GA, Paddock CD, Zaki S, Eremeeva ME, 2007. Rocky Mountain spotted fever, Panama. Emerg Infect Dis 13 :1763–1765.

    • Search Google Scholar
    • Export Citation
  • 11

    Hidalgo M, Orejuela L, Fuya P, Carrillo P, Hernandez J, Parra E, Keng C, Small M, Olano JP, Bouyer D, Castaneda E, Walker D, Valbuena G, 2007. Rocky Mountain spotted fever, Colombia. Emerg Infect Dis 13 :1058–1060.

    • Search Google Scholar
    • Export Citation
  • 12

    Horta MC, Labruna MB, Sangioni LA, Vianna MC, Gennari SM, Galvao MA, Mafra CL, Vidotto O, Schumaker TT, Walker DH, 2004. Prevalence of antibodies to spotted fever group rickettsiae in humans and domestic animals in a Brazilian spotted fever-endemic area in the state of Sao Paulo, Brazil: serologic evidence for infection by Rickettsia rickettsii and another spotted fever group Rickettsia. Am J Trop Med Hyg 71 :93–97.

    • Search Google Scholar
    • Export Citation
  • 13

    Hidalgo M, Sanchez R, Orejuela L, Hernandez J, Walker DH, Valbuena G, 2007. Prevalence of antibodies against spotted fever group rickettsiae in a rural area of Colombia. Am J Trop Med Hyg 77 :378–380.

    • Search Google Scholar
    • Export Citation
  • 14

    Suarez R, Hidalgo M, Nino N, Gonzalez C, Vesga JF, Orejuela L, Sanchez R, Castaneda E, Valbuena G, 2008. Rickettsiae as Etiologic Agents of Febrile Syndromes without Diagnosis in Colombia (in Spanish). Bogota, Colombia: Ediciones Uniandes.

 

 

 

 

A Survey of Antibodies against Rickettsia rickettsii and Ehrlichia chafeensis in Domestic Animals from a Rural Area of Colombia

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  • 1 Grupo de Microbiología, Instituto Nacional de Salud, Bogotá, Colombia; Department of Pathology and Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, Texas

In a rural area of Colombia endemic for Rocky Mountain spotted fever, we performed indirect immunofluorescent antibody assays for Rickettsia spp. and Ehrlichia spp. using sera from randomly sampled dogs and horses to test the use of domestic animals as possible sentinels. Antibodies against Ehrlichia spp. were detected in 8 dogs (31.8%). Antibody titers against Rickettsia rickettsii antigen were positive in 4 dogs (18.2%) and 26 horses (16.3%). These values, albeit not directly comparable, are lower than those previously reported for humans in this region. A systemic approach to understanding dynamics of transmission is needed before implementing the use of domestic animals for disease surveillance activities.

Spotted fever group (SFG) rickettsioses and ehrlichioses are tick-transmitted emerging human infections caused by obligate intracellular gram-negative bacteria belonging to the order Rickettsiales.1 There is a current large re-emergence of Rocky Mountain spotted fever (RMSF) in the Americas; the highest number of RMSF cases reported in one year in the United States (1,514) occurred in 2004,2 and new and large clusters of spotted-fever group rickettsioses have been recently reported from several Latin American countries including Argentina, 3,4 Brazil, 5,6 Peru,7 Mexico,8,9 Panama,10 and Colombia. 11

It was recently suggested that horses could be used as sentinel animals for detection of RMSF in disease-endemic areas, even before human cases of the disease are detected. 12 Therefore, we designed this study to test whether a similar concept could be applied to other areas of Latin America. The study area is particularly relevant because of the endemicity of SFG human rickettsioses. 11,13 We also wished to address the lack of data regarding the presence of Ehrlichia spp. or Rickettsia spp. in domestic mammals in this area of Colombia. Ehrlichiosis have been recognized as infectious diseases in animals for a long time, but they are now being recognized as important emerging zoonoses in humans and there is no data about their importance in Colombia.2

The study area is located in Villeta, Cundinamarca, Colombia, (5°0′53″N, 74°28′29″W), which is 842 meters above sea level, and has an annual average temperature of 26°C and a relative humidity of 80–97%. The estimated horse population in the rural area is of 1,695 animals in 22 villages. The dog population could not be estimated because registration is not mandatory and because most dogs roam freely with access to pasture and forest areas. Horses graze on mixed overgrowth pastures in the study area. Three tick species have been documented in the area: Amblyomma cajennense, Rhipicephalus sanguineus, and Anocentor nitens.

Because of the high mobility of animals within the region, we applied a snowball sampling strategy. In the locations where horses were found, dogs where included for collection of serum samples. During March and April 2008, blood samples were collected from 22 dogs, and 159 horses. An immunofluoresecent antibody assay was performed as previously described. 13 The Taiaçu strain of Rickettsia rickettsii (kindly provided by Dr. Marcelo Labruna, University of Saõ Paulo, Saõ Paulo, Brazil) was used to prepare antigen slides in our laboratory. Slides containing Ehrlichia chaffensis antigen were provided by Dr. Jere McBride (University of Texas Medical Branch, Galveston, TX). We screened samples at a serum dilution of 1:64 to identify positive samples, which were subsequently titered to their end point.

We detected IgG against R. rickettsii in 4 (18.2%) of 22 dogs and 26 (16.3%) of 159 horses (Table 1). Eight (31.8%) dogs had IgG that reacted with E. chaffensis (Table 2). This reactivity may correspond to prior infection with E. canis. Interestingly, the two dogs sampled in the village of Naranjal, where a recent confirmed fatal case of human RMSF was identified, 11 did not contain antibodies against R. rickettsii or E. chaffeensis.

It is generally expected that the seroprevalence of R. rickettsii and E. chafeensis in domestic animals should be higher than in humans 12; this suggestion is a probable reflection of a greater exposure of canines and horses to tick vectors. Conversely, our study suggests that in this disease-endemic region of Colombia the seroprevalence of domestic animals for SFG rickettsioses might be lower than that previously reported in humans (40.3%). 13 However, these studies are not strictly comparable because they were not performed simultaneously and they used different strains of R. rickettsii as antigen. Although firm conclusions cannot be made, the proposed interpretation of our results is plausible because humoral immunity is long lived (many years) in mammals and the high level of cross-reactivity between strains of the same species of Rickettsia make it unlikely that positive samples would not be detected equally well with both types of antigens.

A recent anthropologic study in the study region reported that humans do not perceive ticks as a source of human diseases. 14 Thus, we hypothesize that the contrasting serologic findings in humans and domestic animals may be explained, at least in part, by our observation that persons in this region of Colombia periodically treat their domestic animals with acaricides, but they do not address the presence of ticks on their own bodies. Another possible explanation is the differential preference of the tick species present in this region (including different stages of development) for feeding on humans, horses, or dogs. We conclude that domestic animals can only be used as markers of the activity or presence of tick-transmitted zoonoses if there is a clear understanding of the impact of human behavior (such as the periodic treatment of animals with acaricides) on the dynamics of transmission. Future studies should also address the role of domestic animals in the dynamics of transmission, including the possibility that some animals may serve as reservoirs, amplifiers, or both.

Table 1

End point antibody titers by immunofluorescent antibody assay for Rickettsia rickettsii in horses from Villeta, Colombia

Table 1
Table 2

End point antibody titers by immunofluorescent antibody assay for Rickettsia rickettsii and Ehrlichia chaffensis in dogs from Villeta, Colombia

Table 2

*

Address correspondence to Gustavo Valbuena, Department of Pathology, The University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-0609. E-mail: gvalbuen@utmb.edu

Authors’ addresses: Marylin Hidalgo, Juan Fernando Vesga, and Diana Lizarazo, Instituto Nacional de Salud, Grupo de Microbiología, AV Cll 26 No. 51-60, Bogotá, Colombia, E-mails: mhidalgo@ins.gov.co, jfvesga@cable.net.co, and dianaliz20@yahoo.com. Gustavo Valbuena, Department of Pathology, The University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-0609, E-mail: gval-buen@utmb.edu.

Financial support: This study was supported by grant 1204-04-16332 from Instituto Colombiano para el Desarrollo de la Ciencia y la Tecnología Francisco José de Caldas, Colciencias to Gustavo Valbuena.

Disclaimer: None of the authors has any conflicts of interest.

REFERENCES

  • 1

    Parola P, Paddock CD, Raoult D, 2005. Tick-borne rickettsioses around the world: emerging diseases challenging old concepts. Clin Microbiol Rev 18 :719–756.

    • Search Google Scholar
    • Export Citation
  • 2

    Dumler JS, Madigan JE, Pusterla N, Bakken JS, 2007. Ehrlichioses in humans: epidemiology, clinical presentation, diagnosis, and treatment. Clin Infect Dis 45 (Suppl 1):S45–51.

    • Search Google Scholar
    • Export Citation
  • 3

    Ripoll CM, Remondegui CE, Ordonez G, Arazamendi R, Fusaro H, Hyman MJ, Paddock CD, Zaki SR, Olson JG, Santos-Buch CA, 1999. Evidence of rickettsial spotted fever and ehrlichial infections in a subtropical territory of Jujuy, Argentina. Am J Trop Med Hyg 61 :350–354.

    • Search Google Scholar
    • Export Citation
  • 4

    Paddock CD, Fernandez S, Echenique GA, Sumner JW, Reeves WK, Zaki SR, Remondegui CE, 2008. Rocky Mountain spotted fever in Argentina. Am J Trop Med Hyg 78 :687–692.

    • Search Google Scholar
    • Export Citation
  • 5

    de Lemos ER, Alvarenga FB, Cintra ML, Ramos MC, Paddock CD, Ferebee TL, Zaki SR, Ferreira FC, Ravagnani RC, Machado RD, Guimaraes MA, Coura JR, 2001. Spotted fever in Brazil: a seroepidemiological study and description of clinical cases in an endemic area in the state of Sao Paulo. Am J Trop Med Hyg 65 :329–334.

    • Search Google Scholar
    • Export Citation
  • 6

    Galvao MA, Dumler JS, Mafra CL, Calic SB, Chamone CB, Cesarino, Filho G, Olano JP, Walker DH, 2003. Fatal spotted fever rickettsiosis, Minas Gerais, Brazil. Emerg Infect Dis 9 :1402–1405.

    • Search Google Scholar
    • Export Citation
  • 7

    Schoeler GB, Moron C, Richards A, Blair PJ, Olson JG, 2005. Human spotted fever rickettsial infections. Emerg Infect Dis 11 :622–624.

  • 8

    Zavala-Castro JE, Zavala-Velasquez JE, Walker DH, Ruiz EE, Laviada-Molina H, Olano JP, Ruiz-Sosa JA, Small MA, Dzul-Rosado KR, 2006. Fatal human infection with Rickettsia rickettsii, Yucatan, Mexico. Emerg Infect Dis 12 :672–674.

    • Search Google Scholar
    • Export Citation
  • 9

    Zavala-Velazquez JE, Yu XJ, Walker DH, 1996. Unrecognized spotted fever group rickettsiosis masquerading as dengue fever in Mexico. Am J Trop Med Hyg 55 :157–159.

    • Search Google Scholar
    • Export Citation
  • 10

    Estripeaut D, Aramburu MG, Saez-Llorens X, Thompson HA, Dasch GA, Paddock CD, Zaki S, Eremeeva ME, 2007. Rocky Mountain spotted fever, Panama. Emerg Infect Dis 13 :1763–1765.

    • Search Google Scholar
    • Export Citation
  • 11

    Hidalgo M, Orejuela L, Fuya P, Carrillo P, Hernandez J, Parra E, Keng C, Small M, Olano JP, Bouyer D, Castaneda E, Walker D, Valbuena G, 2007. Rocky Mountain spotted fever, Colombia. Emerg Infect Dis 13 :1058–1060.

    • Search Google Scholar
    • Export Citation
  • 12

    Horta MC, Labruna MB, Sangioni LA, Vianna MC, Gennari SM, Galvao MA, Mafra CL, Vidotto O, Schumaker TT, Walker DH, 2004. Prevalence of antibodies to spotted fever group rickettsiae in humans and domestic animals in a Brazilian spotted fever-endemic area in the state of Sao Paulo, Brazil: serologic evidence for infection by Rickettsia rickettsii and another spotted fever group Rickettsia. Am J Trop Med Hyg 71 :93–97.

    • Search Google Scholar
    • Export Citation
  • 13

    Hidalgo M, Sanchez R, Orejuela L, Hernandez J, Walker DH, Valbuena G, 2007. Prevalence of antibodies against spotted fever group rickettsiae in a rural area of Colombia. Am J Trop Med Hyg 77 :378–380.

    • Search Google Scholar
    • Export Citation
  • 14

    Suarez R, Hidalgo M, Nino N, Gonzalez C, Vesga JF, Orejuela L, Sanchez R, Castaneda E, Valbuena G, 2008. Rickettsiae as Etiologic Agents of Febrile Syndromes without Diagnosis in Colombia (in Spanish). Bogota, Colombia: Ediciones Uniandes.

Author Notes

Reprint requests: Gustavo Valbuena, Department of Pathology, The University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-0609, E-mail: gvalbuen@utmb.edu.
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