AJTMH HINARI
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Am. J. Trop. Med. Hyg., 74(5), 2006, pp. 908-914
Copyright © 2006 by The American Society of Tropical Medicine and Hygiene

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via ISI Web of Science (2)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by FARFÁN-ALE, J. A.
Right arrow Articles by BEATY, B. J.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by FARFÁN-ALE, J. A.
Right arrow Articles by BEATY, B. J.
Related Collections
Right arrow West Nile

ANTIBODIES TO WEST NILE VIRUS IN ASYMPTOMATIC MAMMALS, BIRDS, AND REPTILES IN THE YUCATAN PENINSULA OF MEXICO

JOSÉ A. FARFÁN-ALE, BRADLEY J. BLITVICH, NICOLE L. MARLENEE, MARÍA A. LOROÑO-PINO, FERNANDO PUERTO-MANZANO, JULIÁN E. GARCÍA-REJÓN, ELSY P. ROSADO-PAREDES, LUIS F. FLORES-FLORES, ANDRES ORTEGA-SALAZAR, JAIDY CHÁVEZ-MEDINA, JUAN C. CREMIEUX-GRIMALDI, FAVIÁN CORREA-MORALES, GERSON HERNÁNDEZ-GAONA, JORGE F. MÉNDEZ-GALVÁN, AND BARRY J. BEATY*
Laboratorio de Arbovirologia, Centro de Investigaciones Regionales Dr. Hideyo Noguchi, Universidad Autónoma de Yucatan, Merida, Yucatan, Mexico; Arthropod-Borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado; Centro Nacional de Vigilancia Epidemiológica y Control de Enfermedades, Secretaría de Salud, Distrito Federal, Mexico City, Mexico


ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Surveillance for evidence of West Nile virus (WNV) infection in taxonomically diverse vertebrates was conducted in the Yucatan Peninsula of Mexico in 2003 and 2004. Sera from 144 horses on Cozumel Island, Quintana Roo State, 415 vertebrates (257 birds, 52 mammals, and 106 reptiles) belonging to 61 species from the Merida Zoo, Yucatan State, and 7 farmed crocodiles in Ciudad del Carmen, Campeche State were assayed for antibodies to flaviviruses. Ninety (62%) horses on Cozumel Island had epitope-blocking enzyme-linked immunosorbent assay (ELISA) antibodies to flaviviruses, of which 75 (52%) were seropositive for WNV by plaque reduction neutralization test (PRNT). Blocking ELISA antibodies to flaviviruses also were detected in 13 (3%) animals in the Merida Zoo, including 7 birds and 2 mammals (a jaguar and coyote) seropositive for WNV by PRNT. Six (86%) crocodiles in Campeche State had PRNT-confirmed WNV infections. All animals were healthy at the time of serum collections and none had a history of WNV-like illness.


INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
West Nile virus (WNV; genus Flavivirus, family Flaviviridae) was first reported in the Western Hemisphere in New York in 1999, and since then has rapidly spread across the United States and southern Canada where it has been responsible for > 16,000 reported cases of human disease, > 20,000 reported cases of equine encephalitis, and tens of thousands of bird deaths.1–5 In contrast, there has not been a major outbreak of WNV disease in Mexico, despite serologic evidence of widespread WNV activity.6–12 The Secretary of Health of Mexico (Secretaría de Salud) has reported 7 human cases of WNV disease in Mexico, and all of these were confined to northern Mexico near the U.S. border (http://www.cenave.gob.mx/von). In addition, the Secretary of Agriculture, Livestock, Rural Development, Fishing and Food of Mexico (Secretaría de Agricultura, Ganadería, Desarrollo Rural, Pesca y Alimentación; SAGARPA) identified epitope-blocking enzyme-linked immunosorbent assay (ELISA) antibodies to WNV in 1,023 of 3,523 (29%) horses in Mexico in 2004. All were asymptomatic. In contrast, approximately 10% of horses infected with WNV in the United States present with neurologic signs, and the case-fatality rate is nearly 40%.13–15

WNV is maintained in cycles between birds and Culex species mosquitoes.16–19 Humans, horses and other mammals are typically dead-end hosts. In the United States, evidence of WNV infection has been detected in at least 208 species of birds and 29 species of mammals (Caffrey C and others, http://www.cdc.gov/ncidod/dvbid/westnile/conf/pdf/Caffrey_4_04.pdf). There have also been occasional reports of WNV infections in reptiles. For example, antibodies to WNV were detected in a crocodile monitor lizard (Varanus salvadori) with neurologic signs in a zoo in Maryland (Travis D and others, unpublished data). Moreover, WNV was responsible for significant mortality in farmed American alligators (Alligator mississippiensis) in Georgia during separate outbreaks in 2001 and 2002.20,21 The role of reptiles in the epidemiology of WNV is unclear, although recent evidence suggests that American alligators are competent hosts for WNV.22

We previously demonstrated the presence of WNV in Yucatan State, with antibodies to WNV detected in migratory and resident birds and in horses.8,10 However, we have not detected dead birds or horses. In addition, there is no conclusive evidence demonstrating that WNV has caused mortality in birds or horses in Central America, South America, or the Caribbean, despite evidence of WNV activity in these regions.23–29 To investigate the potential for asymptomatic WNV infection in other species, in 2003 and 2004, we tested taxonomically diverse vertebrates in the Yucatan Peninsula of Mexico for evidence of WNV infection.


MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
Study sites. Sera were obtained from vertebrates at three sites: a private horse ranch (Global Positioning System [GPS] coordinates 20°51'667''N, 86°94'167''W) on Cozumel Island in Quintana Roo State, the El Centenario Zoo (GPS coordinates 20°96'744''N, 89°64'056''W) in Merida, Yucatan State, and a crocodile farm (GPS coordinates 18°42'24''N, 91°40'58''W) in Ciudad del Carmen, Campeche State (Figure 1Go). Cozumel is a 460 km2 coralline limestone island approximately 16 km off the east coast of the Mexican mainland. It is a popular tourist destination. The main vegetation is coastal mangrove forest, tropical deciduous forest, and tropical semi-deciduous forest. The El Centenario Zoo is in the metropolitan area of Merida, the capital of Yucatan State. Ciudad del Carmen is located on Carmen Island, a 37-km-long and 3.2-km-wide calcareous-sand barrier island.


Figure 1
View larger version (29K):
[in this window]
[in a new window]
  		    FIGURE 1. A, Location of the Yucatan Peninsula of Mexico. B, Surveillance sites for West Nile virus.

 
Sample population and sera collection. Samples were not obtained as part of a serosurveillance program, but were sent to the Laboratorio de Arbovirologia at the Universidad Autónoma de Yucatán, by the veterinarians or caregivers of the respective animals for arbovirus diagnosis. None of the animals had been vaccinated against WNV. All animals were regularly monitored (usually daily) by their caregivers for signs of WNV-like illness (e.g., fever, ataxia, weakness, seizures, paralysis). There had been no deaths caused by suspected WNV infection at any of the study sites before serum collections. The horses on Cozumel Island were from 2 months to 26 years old, with a mean age of 10 years. The horses, which were used by tourists for horseback riding, had never left Cozumel Island. Serum samples were collected from captive avians, mammals, and reptiles at the Merida Zoo. The Crocodile Farm contained 268 crocodiles, including 42 adults obtained from a crocodile farm in Tabasco State and zoos in Campeche State and Yucatan State. Adults were housed in tanks containing natural flowing water maintained at a temperature of 25–34°C. Blood samples were diluted five-fold using sterile field diluent (phosphate-buffered saline containing 1.5% bovine albumin, 100 units/mL of penicillin, 100 µg/mL of streptomycin, 250 µg/mL of amphotericin B) and placed on wet ice (4°C).

Epitope-blocking ELISA. Sera were first tested for antibodies to flaviviruses by blocking ELISA as previously described.30,31 ELISAs were performed using the WNV-specific monoclonal antibody (MAb) 3.1112G (Chemicon International, Temecula, CA) or the flavivirus-specific MAb 6B6C-1, obtained from the Division of Vector-Borne Infectious Diseases, Centers for Disease Control and Prevention (Fort Collins, CO). The blocking ELISA technique is species independent and does not require species-specific antibodies. The ability of the test sera to block the binding of the MAbs to WNV antigen was compared with the blocking ability of control serum without antibody to WNV. Control sera were obtained from horses and chickens (Vector Laboratories, Burlingame, CA) and American alligators (generously provided by Dr. R. Bowen, Animal Reproduction and Biotechnology Laboratory, Colorado State University, Fort Collins, CO) and were used when testing sera from mammals, birds, and reptiles, respectively. Data were expressed as relative percentages and inhibition values ≥ 30% were considered as indicating the presence of viral antibodies.30

Plaque reduction neutralization test (PRNT). All sera that were demonstrated to contain antibodies to flaviviruses by the blocking ELISA test, and selected flavivirus negative sera, were subsequently tested by PRNT in the Biosafety Level 3 facilities at Colorado State University according to standard methods.32 PRNTs were done using WNV (strain NY99-35261-11), Saint Louis encephalitis virus (SLEV, strain TBH-28), Ilhéus virus (ILHV, strain Original), and Bussuquara virus (BSQV, strain BeAn-4073). SLEV, ILHV, and BSQV were included in these studies because they occur in Latin America, and are known to react with antibodies to WNV.16,33 Viruses were obtained from the World Health Organization Center for Arbovirus Reference and Research maintained at the Centers for Disease Control and Prevention, Division of Vector-Borne Infectious Diseases (Fort Collins, CO). The PRNTs were performed using African green monkey kidney (Vero) cells. Sera were initially tested at a dilution of 1:20. Those that reduced the number of plaques by ≥ 70% (PRNT70) were titrated. Titers were expressed as the reciprocal of serum dilutions yielding ≥ 90% reduction in the number of plaques (PRNT90). For etiologic diagnosis, the PRNT90 antibody titer to the respective virus was required to be at least four-fold greater than that to the other flaviviruses tested. The PRNT is the gold standard in arbovirus serology; thus, PRNT results were used to determine the final serodiagnosis.


RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 REFERENCES
 
Seroprevalence of WNV in horses on Cozumel Island. Blood samples were obtained from 144 horses on Cozumel Island in May 2003. Ninety (62.5%) had antibodies to flaviviruses by blocking ELISA, including 84 (58.3%) positive by the WNV-specific ELISA. The average inhibitions of MAb binding for sera positive by flavivirus-specific and WNV-specific ELISA were 91% and 83%, respectively. Representative serologic data from 24 flavivirus-positive horses are shown in Table 1Go. Sera with blocking ELISA antibodies to flaviviruses were examined by PRNT using WNV, SLEV, ILHV, and BSQV. Seventy-five (52.1%) horses were seropositive for WNV by PRNT, 1 (0.7%) was seropositive for SLEV by PRNT, 13 (9.0%) had antibodies to a flavivirus(es) of undetermined etiology, and 1 (0.7%) had no neutralizing antibodies to these flaviviruses (Table 2Go). Seventy-two (96%) of the 75 horses seropositive for WNV by PRNT were positive in the WNV-specific ELISA. The WNV seropositive horses had WNV PRNT90 titers of 40 (n = 2), 80 (n = 4), 160 (n = 10), 320 (n = 21), 640 (n = 18), and ≥ 1,280 (n = 20). The SLEV seropositive horse had an SLEV PRNT90 titer of 640. All horses appeared to be healthy at the time of serum collections and none had a history of WNV-like illness. All horses remained healthy during the six months that followed.


View this table:
[in this window]
[in a new window]
 
TABLE 1
Serologic summary of a subset of horses with blocking ELISA antibodies to flaviviruses, Cozumel Island, Mexico, May 2003*
 

View this table:
[in this window]
[in a new window]
 
TABLE 2
Concordance between the blocking ELISA and PRNT for horses, Cozumel Island, Mexico*
 
Seroprevalence of WNV in mammals, birds, and reptiles in the Merida Zoo. Blood samples were obtained from 415 animals in the Merida Zoo, Yucatan State between September 2003 and September 2004. The total included 257 birds (belonging to 46 species, 19 families, and 13 orders), 52 mammals (belonging 11 species, 6 families, and 3 orders) and 106 reptiles (belonging to 4 species, 2 families, and 2 orders) (Table 3Go). Birds most commonly sampled were ruddy ground doves (n = 44), clay-colored thrushes (n = 34), and Indian peafowls (n = 29). Mammalian species most commonly sampled were horses (n = 16), white-tailed deer (n = 14), and northern raccoons (n = 8). Reptilian species most commonly sampled were furrowed wood turtles (n = 60), red-eared sliders (n = 39), and Morelet’s crocodiles (n = 6).


View this table:
[in this window]
[in a new window]
 
TABLE 3
Birds, mammals, and reptiles sampled during WNV surveillance in the Merida zoo, Yucatan State, Mexico*
 
Sera from 11 (4.3%) birds and 2 (3.8%) mammals had blocking ELISA antibodies to flaviviruses (Table 4Go). None of the reptiles had blocking ELISA antibodies to flaviviruses. Seven (2.7%) birds belonging to 5 species and 2 (3.8%) mammals (a jaguar and coyote) were seropositive for WNV by PRNT. The seropositive birds were a black vulture (n = 2), ruddy ground dove (n = 2), great horned owl (n = 1), peacock (n = 1), and plain chachalaca (n = 1). One plain chachalaca (ZO-373) had an apparent SLEV infection and another (ZO-372) had antibodies to an undetermined flavivirus. There were several disparities between the blocking ELISA and PRNT data. Most notably, a ruddy ground dove (ZO-405) seropositive for WNV by PRNT was negative in the WNV-specific ELISA and a plain chachalaca (ZO-373) seropositive for SLEV by PRNT was positive in the WNV-specific ELISA. All animals were healthy at the time of serum collections and none had a history of WNV-like illness. At the time of writing, none of the animals in the zoo, including those not sampled, had signs of WNV-like illness.


View this table:
[in this window]
[in a new window]
 
TABLE 4
Summary of vertebrates at the Merida zoo with antibodies to flaviviruses*
 
Seroprevalence of WNV in farmed crocodiles in Campeche State. Blood samples were obtained from seven adult Morelet’s crocodiles in Ciudad del Carmen, Campeche State in January 2004. Six crocodiles were tank mates; the other was held in a separate tank because it had been injured. Six (86%) of the crocodiles had antibodies to WNV by blocking ELISA and PRNT (Table 5Go). All were tank mates. The injured crocodile had no antibodies to WNV, as determined by both techniques. Four crocodiles had PRNT titers to WNV of 640 and two had titers of 5,120. The latter two crocodiles had PRNT titers to SLEV of 20; all others had titers to SLEV < 20. Antibodies to ILHV and BSQV were not detected in any crocodiles. Thus, six crocodiles were seropositive for WNV. All crocodiles, including those not sampled, showed no signs of illness at the time of the serosurvey and during the three months that followed. None of the crocodiles had a history of illness.


View this table:
[in this window]
[in a new window]
 
TABLE 5
Summary of serologic results for farmed crocodiles, Campeche State, Mexico, January 2004*
 

DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
REFERENCES
 
We detected neutralizing antibodies to WNV in asymptomatic mammals, birds and reptiles in the Yucatan Peninsula of Mexico. Of particular interest is the high (52%) seroprevalence for WNV in horses on Cozumel Island. Likewise, the SAGARPA reported a high (29%) seroprevalence of WNV in asymptomatic horses in Mexico in 2004. However, unlike the SAGARPA, all animals in our studies were regularly monitored for signs of illness before and after serum collections. In addition, all sera with blocking ELISA antibodies to WNV were further tested by PRNT. Thus, our studies confirm and expand upon the SAGARPA results and demonstrate that a WNV infection can be asymptomatic in vertebrates in Mexico. The WNV seroprevalence in this serosurvey is comparable to seroprevalences reported in several other studies. For example, Quirin and others detected IgG ELISA antibodies to WNV in 68 (50%) of 136 horses in Guadeloupe in 2003.29 Autorino and others sampled 155 horses from 16 stables after an outbreak of WNV in Italy in 1998.34 Sixty-three (41%) horses had IgG ELISA antibodies to WNV. The horses with antibodies to WNV were confined to nine stables, and the overall WNV seroprevalence in these stables was 49%.

The seroprevalence for WNV in birds and mammals in the Merida Zoo was 2.7% and 3.8%, respectively. Considerably higher seroprevalences for WNV have been reported in captive wildlife populations in the United States. Approximately 36% of primates sampled at a primate center in St. Tammany Parish, Louisiana in 2002 and 34% of captive birds and 8% of captive mammals sampled in the Bronx Zoo in 1999–2000 were seropositive for WNV.35,36 One explanation for the higher WNV seroprevalence in animals in the Bronx Zoo compared with the present study is that many animals in the Bronx Zoo exhibited signs of WNV-like illness, and symptomatic animals were presumably more likely to be assayed for evidence of WNV infection. The Bronx Zoo was located in the epicenter of the WNV outbreak in 1999, which could also account for this higher seroprevalence. Similarly, St. Tammany Parish was the focus of intense WNV activity in 2002. The difference in WNV seroprevalence in St. Tammany Parish and Merida serosurveys could also be due to the differences in species tested; no primates from the Merida Zoo were assayed for evidence of WNV infection.

Antibodies to WNV were not detected in any red-eared slider turtles in the Merida Zoo. However, antibodies to WNV and closely-related flaviviruses have occasionally been detected in other turtle species during serosurveys.37–39 For example, antibodies to WNV were detected in a Caspian turtle (Clemmys caspica) in Israel.37 While our studies were in progress, Klenk and Komar reported that red-eared sliders subcutaneously inoculated with WNV do not develop detectable viremia.40

Our data suggest a high seroprevalence (86%) for WNV in crocodiles in the crocodile farm in Ciudad del Carmen. However, the crocodiles had travel histories and may have been infected with WNV in the neighboring states of Yucatan or Tabasco. A high seroprevalence (70%) for WNV was also observed in farmed Nile crocodiles (Crocodylus niloticus) in Israel in 2002.41 However, since the sample populations in the Mexican and Israeli serosurveys were small (n = 7 and 20, respectively), much larger studies are needed to provide more precise estimates of the WNV seroprevalence. No signs of illness were observed in any crocodiles in these two serosurveys, whereas > 1,250 alligators died during the WNV outbreaks in Georgia.20,41

There are a number of possible explanations for the absence of WNV-associated illness in vertebrates in Mexico. Pre-existing immunity to other flaviviruses may provide partial protection to WNV infection.42,43 For example, dengue viruses (DENV) are endemic in many regions of Mexico, and in areas such as Merida DENV seroprevalence rates in humans may be > 80%.44 However, pre-existing immunity to DENV does not account for the apparent lack of WNV-associated equine and avian mortality in Mexico because DENV does not usually replicate in non-primate vertebrates.45 It is unlikely that antibodies to SLEV, ILHV, or BSQV are conferring resistance against subsequent WNV infection. The prevalence of these virus infections in this study, and in other recent arbovirus surveillance studies in the Yucatan, was low.8,10,24 However, antibodies to a different, unrecognized flavivirus may provide protection from disease during subsequent WNV infection.

The absence of WNV-associated illness in southern Mexico may also be due to infection with an avirulent strain of WNV or a closely related flavivirus. An attenuated WNV may have emerged in the Yucatan Peninsula. In this regard, certain plaques obtained from a WNV isolate from Tabasco State in southern Mexico (denoted as TM171-03) were attenuated for mouse neuroinvasiveness and neurovirulence.7,46 Several WNV isolates from Texas with small plaque and temperature-sensitive phenotypes were also attenuated for neuroinvasiveness in mice, although none were attenuated for neurovirulence.47 There are limited sequence data for WNV in Mexico. TM171-03 has been completely sequenced, and three WN viruses from northern Mexico have been partially sequenced.46,48,49 The isolation and characterization of additional WNVs in Mexico is needed to address these issues. Alternatively, animals considered seropositive for WNV may have been infected with a closely related virus not included in the PRNT analysis, rather than with WNV.

Finally, the relative lack of WNV-associated mortality in vertebrate hosts in the Yucatan may also be attributed to differences in biodiversity between the United States (and northern Mexico) and the Yucatan. The species composition and susceptibility of hosts and vectors in the two regions may differ dramatically. For whatever reason, the introduction of WNV into the Yucatan has not yet resulted in observed morbidity and mortality in humans, horses, and birds as occurred in the United States. Elucidation of the mechanisms that have conditioned the differences in the epidemic and epizootic potential of WNV in the Yucatan and other countries in Central America would be a significant contribution to public health.

Received April 17, 2005. Accepted for publication December 21, 2005.

Acknowledgments: We thank Dr. Charles Calisher (Arthropod-Borne and Infectious Diseases Laboratory, Colorado State University, Fort Collins, CO) for his thorough review of the manuscript, and Dr. Richard Bowen (Animal Reproduction and Biotechnology Laboratory, Colorado State University, Fort Collins, CO) for generously providing control serum for the blocking ELISA. We also thank Waldemar Santamaría, Luis Chulim-Perera, Mildred López-Uribe, and Genny López-Uribe (Universidad Autónoma de Yucatan, Merida, Yucatan, Mexico) for assisting in the collection of samples. We are greatly appreciative of all personnel from the El Centenario Zoo in Merida, the crocodile farm in Ciudad del Carmen, and the horse ranch on Cozumel Island for providing samples used in these studies.

Financial support: This study was supported by grant U50 CCU820510 from the Centers for Disease Control and Prevention and in part by grant AI45430 from the National Institutes of Health.

* Address correspondence to Barry J. Beaty, Arthropod-Borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523. E-mail: bbeaty{at}colostate.edu Back

Authors’ addresses: José A. Farfán-Ale, Fernando Puerto-Manzano, Julián E. García-Rejón, Elsy P. Rosado-Paredes, Luis F. Flores-Flores, Andres Ortega-Salazar, and Jaidy Chávez-Medina, Laboratorio de Arbovirologia, Centro de Investigaciones Regionales Dr. Hideyo Noguchi, Universidad Autónoma de Yucatán, Av. Itzaes No. 490 x 59, Centro, Merida, Yucatan, México 97000, Telephone 52-999-924-6412, Fax: 52-999-923-1804. Bradley J. Blitvich, Nicole L. Marlenee, María A. Loroño-Pino, and Barry J. Beaty, Arthropod-Borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, Telephone: 970-491-4383, Fax: 970-491-8323, E-mail: bbeaty{at}colostate.edu. Juan C. Cremieux-Grimaldi, Favián Correa-Morales, Gerson Hernández-Gaona, and Jorge F. Méndez-Galván, Centro Nacional de Vigilancia Epidemiológica y Control de Enfermedades, Secretaría de Salud, Benjamín Franklin No. 132 Colonia Escandón Deleg. Miguel Hidalgo, Mexico City DF 11800, Mexico, Telephone: 52-2614-6361 Fax: 52-2614-6362.

Reprint requests: Barry J. Beaty, Arthropod-Borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523.


REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 

  1. Lanciotti RS, Roehrig JT, Deubel V, Smith J, Parker M, Steele K, Crise B, Volpe KE, Crabtree MB, Scherret JH, Hall RA, MacKenzie JS, Cropp CB, Panigrahy B, Ostlund E, Schmitt B, Malkinson M, Banet C, Weissman J, Komar N, Savage HM, Stone W, McNamara T, Gubler DJ, 1999. Origin of the West Nile virus responsible for an outbreak of encephalitis in the northeastern United States. Science 286: 2333–2337.[Abstract/Free Full Text]
  2. Nash D, Mostashari F, Fine A, Miller J, O’Leary D, Murray K, Huang A, Rosenberg A, Greenberg A, Sherman M, Wong S, Layton M, 2001. The outbreak of West Nile virus infection in the New York City area in 1999. N Engl J Med 344: 1807–1814.[Abstract/Free Full Text]
  3. O’Leary DR, Marfin AA, Montgomery SP, Kipp AM, Lehman JA, Biggerstaff BJ, Elko VL, Collins PD, Jones JE, Campbell GL, 2004. The epidemic of West Nile virus in the United States, 2002. Vector Borne Zoonotic Dis 4: 61–70.[ISI][Medline]
  4. 2003. West Nile virus activity–United States, November 20–25, 2003. MMWR Morb Mortal Wkly Rep 52: 1160.[Medline]
  5. 2004. West Nile virus activity–United States, November 9–16, 2004. MMWR Morb Mortal Wkly Rep 53: 1071–1072.[Medline]
  6. Blitvich BJ, Fernandez-Salas I, Contreras-Cordero JF, Marlenee NL, Gonzalez-Rojas JI, Komar N, Gubler DJ, Calisher CH, Beaty BJ, 2003. Serologic evidence of West Nile virus infection in horses, Coahuila State, Mexico. Emerg Infect Dis 9: 853–856.[ISI][Medline]
  7. Estrada-Franco JG, Navarro-Lopez R, Beasley DW, Coffey L, Carrara AS, Travassos da Rosa A, Clements T, Wang E, Ludwig GV, Cortes AC, Ramirez PP, Tesh RB, Barrett AD, Weaver SC, 2003. West Nile virus in Mexico: evidence of widespread circulation since July 2002. Emerg Infect Dis 9: 1604–1607.[ISI][Medline]
  8. Farfan-Ale JA, Blitvich BJ, Lorono-Pino MA, Marlenee NL, Rosado-Paredes EP, Garcia-Rejon JE, Flores-Flores LF, Chulim-Perera L, Lopez-Uribe M, Perez-Mendoza G, Sanchez-Herrera I, Santamaria W, Moo-Huchim J, Gubler DJ, Cropp BC, Calisher CH, Beaty BJ, 2004. Longitudinal studies of West Nile virus infection in avians, Yucatan State, Mexico. Vector Borne Zoonotic Dis 4: 3–14.[Medline]
  9. Fernandez-Salas I, Contreras-Cordero JF, Blitvich BJ, Gonzalez-Rojas JI, Cavazos-Alvarez A, Marlenee NL, Elizondo-Quiroga A, Lorono-Pino MA, Gubler DJ, Cropp BC, Calisher CH, Beaty BJ, 2003. Serologic evidence of West Nile Virus infection in birds, Tamaulipas State, Mexico. Vector Borne Zoonotic Dis 3: 209–213.[Medline]
  10. Lorono-Pino MA, Blitvich BJ, Farfan-Ale JA, Puerto FI, Blanco JM, Marlenee NL, Rosado-Paredes EP, Garcia-Rejon JE, Gubler DJ, Calisher CH, Beaty BJ, 2003. Serologic evidence of West Nile virus infection in horses, Yucatan State, Mexico. Emerg Infect Dis 9: 857–859.[ISI][Medline]
  11. Marlenee NL, Lorono-Pino MA, Beaty BJ, Blitvich BJ, Fernandez Salas I, Contreras Cordero JF, Gonzalez Rojas JI, 2004. Detection of antibodies to West Nile and Saint Louis encephalitis viruses in horses. Salud Publica Mex 46: 373–375.[Medline]
  12. Ulloa A, Langevin SA, Mendez-Sanchez JD, Arredondo-Jimenez JI, Raetz JL, Powers AM, Villarreal-Trevino C, Gubler DJ, Komar N, 2003. Serologic survey of domestic animals for zoonotic arbovirus infections in the Lacandon Forest region of Chiapas, Mexico. Vector Borne Zoonotic Dis 3: 3–9.[Medline]
  13. Bunning ML, Bowen RA, Cropp CB, Sullivan KG, Davis BS, Komar N, Godsey MS, Baker D, Hettler DL, Holmes DA, Biggerstaff BJ, Mitchell CJ, 2002. Experimental infection of horses with West Nile virus. Emerg Infect Dis 8: 380–386.[ISI][Medline]
  14. Castillo-Olivares J, Wood J, 2004. West Nile virus infection of horses. Vet Res 35: 467–483.[Medline]
  15. Ostlund EN, Crom RL, Pedersen DD, Johnson DJ, Williams WO, Schmitt BJ, 2001. Equine West Nile encephalitis, United States. Emerg Infect Dis 7: 665–669.[ISI][Medline]
  16. Burke D, Monath TP, 2001. Flaviviruses. Knipe D.M. HPM, ed. Fields Virology. Philadelphia: Lippincott Williams and Wilkins, 1043–1126.
  17. Komar N, 2003. West Nile virus: epidemiology and ecology in North America. Adv Virus Res 61: 185–234.[Medline]
  18. Kramer LD, Bernard KA, 2001. West Nile virus in the western hemisphere. Curr Opin Infect Dis 14: 519–525.[ISI][Medline]
  19. McLean RG, Ubico SR, Docherty DE, Hansen WR, Sileo L, McNamara TS, 2001. West Nile virus transmission and ecology in birds. Ann N Y Acad Sci 951: 54–57.[Abstract/Free Full Text]
  20. Miller DL, Mauel MJ, Baldwin C, Burtle G, Ingram D, Hines ME II, Frazier KS, 2003. West Nile virus in farmed alligators. Emerg Infect Dis 9: 794–799.[Medline]
  21. Jacobson ER, Ginn PE, Troutman JM, Farina L, Stark L, Klenk K, Burkhalter KL, Komar N, 2005. West Nile virus infection in farmed American alligators (Alligator mississippiensis) in Florida. J Wildl Dis 41: 96–106.[Abstract/Free Full Text]
  22. Klenk K, Snow J, Morgan K, Bowen R, Stephens M, Foster F, Gordy P, Beckett S, Komar N, Gubler D, Bunning M, 2004. Alligators as West Nile virus amplifiers. Emerg Infect Dis 10: 2150–2155.[ISI][Medline]
  23. Cruz L, Cardenas VM, Abarca M, Rodriguez T, Reyna RF, Serpas MV, Fontaine RE, Beasley DW, da Rosa AP, Weaver SC, Tesh RB, Powers AM, Suarez-Rangel G, 2005. Short report: serologic evidence of West Nile virus activity in El Salvador. Am J Trop Med Hyg 72: 612–615.[Abstract/Free Full Text]
  24. Dupuis AP 2nd, Marra PP, Kramer LD, 2003. Serologic evidence of West Nile virus transmission, Jamaica, West Indies. Emerg Infect Dis 9: 860–863.[ISI][Medline]
  25. Komar O, Robbins MB, Klenk K, Blitvich BJ, Marlenee NL, Burkhalter KL, Gubler DJ, Gonzalvez G, Pena CJ, Peterson AT, Komar N, 2003. West Nile virus transmission in resident birds, Dominican Republic. Emerg Infect Dis 9: 1299–1302.[ISI][Medline]
  26. Komar O, Robbins MB, Contreras GG, Benz BW, Klenk K, Blitvich BJ, Marlenee NL, Burkhalter KL, Beckett S, Gonzalvez G, Pena CJ, Peterson AT, Komar N, 2005. West Nile virus survey of birds and mosquitoes in the Dominican Republic. Vector Borne Zoonotic Dis 5: 120–126.[Medline]
  27. Lefrancois T, Blitvich BJ, Pradel J, Molia S, Vachiery N, Pallavicini G, Marlenee NL, Zientara S, Petitclerc M, Martinez D, 2005. West Nile virus surveillance, Guadeloupe, 2003–2004. Emerg Infect Dis 11: 1100–1103.[Medline]
  28. Mattar S, Edwards E, Laguado J, González M, Alvarez J, Komar N, 2005. West Nile virus antibodies in Colombian horses. Emerg Infect Dis 11: 1497–1498.[Medline]
  29. Quirin R, Salas M, Zientara S, Zeller H, Labie J, Murri S, Lefrancois T, Petitclerc M, Martinez D, 2004. West Nile virus, Guadeloupe. Emerg Infect Dis 10: 706–708.[ISI][Medline]
  30. Blitvich BJ, Marlenee NL, Hall RA, Calisher CH, Bowen RA, Roehrig JT, Komar N, Langevin SA, Beaty BJ, 2003. Epitope-blocking enzyme-linked immunosorbent assays for the detection of serum antibodies to west nile virus in multiple avian species. J Clin Microbiol 41: 1041–1047.[Abstract/Free Full Text]
  31. Blitvich BJ, Bowen RA, Marlenee NL, Hall RA, Bunning ML, Beaty BJ, 2003. Epitope-blocking enzyme-linked immunosorbent assays for detection of West Nile virus antibodies in domestic mammals. J Clin Microbiol 41: 2676–2679.[Abstract/Free Full Text]
  32. Beaty B, Calisher CH, Shope RE, 1995. Arboviruses. Lennette EH, Lennette DA, Lennette ET, eds. Viral, Rickettsial, and Chlamydial Infections. Seventh edition. Washington, DC: American Public Health Association, 189–212.
  33. Calisher CH, Karabatsos N, Dalrymple JM, Shope RE, Porterfield JS, Westaway EG, Brandt WE, 1989. Antigenic relationships between flaviviruses as determined by cross-neutralization tests with polyclonal antisera. J Gen Virol 70: 37–43.[Abstract/Free Full Text]
  34. Autorino GL, Battisti A, Deubel V, Ferrari G, Forletta R, Giovannini A, Lelli R, Murri S, Scicluna MT, 2002. West Nile virus epidemic in horses, Tuscany region, Italy. Emerg Infect Dis 8: 1372–1378.[Medline]
  35. Ludwig GV, Calle PP, Mangiafico JA, Raphael BL, Danner DK, Hile JA, Clippinger TL, Smith JF, Cook RA, McNamara T, 2002. An outbreak of West Nile virus in a New York City captive wildlife population. Am J Trop Med Hyg 67: 67–75.[Abstract]
  36. Ratterree MS, da Rosa AP, Bohm RP Jr, Cogswell FB, Phillippi KM, Caillouet K, Schwanberger S, Shope RE, Tesh RB, 2003. West Nile virus infection in nonhuman primate breeding colony, concurrent with human epidemic, southern Louisiana. Emerg Infect Dis 9: 1388–1394.[Medline]
  37. Nir Y, Lasowski Y, Avivi A, Cgoldwasser R, 1969. Survey for antibodies to arboviruses in the serum of various animals in Israel during 1965–1966. Am J Trop Med Hyg 18: 416–422.[Abstract/Free Full Text]
  38. Shortridge KF, Oya A, Kobayashi M, Yip DY, 1975. Arbovirus infections in reptiles: studies on the presence of Japanese encephalitis virus antibody in the plasma of the turtle, Trionyx sinensis. Southeast Asian J Trop Med Public Health 6: 161–169.[Medline]
  39. Whitney E, Jamnback H, Means RG, Watthews TH, 1968. Arthropod-borne-virus survey in St. Lawrence County, New York. Arbovirus reactivity in serum from amphibians, reptiles, birds, and mammals. Am J Trop Med Hyg 17: 645–650.[Abstract/Free Full Text]
  40. Klenk K, Komar N, 2003. Poor replication of West Nile virus (New York 1999 strain) in three reptilian and one amphibian species. Am J Trop Med Hyg 69: 260–262.[Abstract/Free Full Text]
  41. Steinman A, Banet-Noach C, Tal S, Levi O, Simanov L, Perk S, Malkinson M, Shpigel N, 2003. West Nile virus infection in crocodiles. Emerg Infect Dis 9: 887–889.[Medline]
  42. Tesh RB, Travassos da Rosa AP, Guzman H, Araujo TP, Xiao SY, 2002. Immunization with heterologous flaviviruses protective against fatal West Nile encephalitis. Emerg Infect Dis 8: 245–251.[ISI][Medline]
  43. Xiao SY, Guzman H, da Rosa AP, Zhu HB, Tesh RB, 2003. Alteration of clinical outcome and histopathology of yellow fever virus infection in a hamster model by previous infection with heterologous flaviviruses. Am J Trop Med Hyg 68: 695–703.[Abstract/Free Full Text]
  44. Lorono-Pino MA, Farfan-Ale JA, Zapata-Peraza AL, Rosado-Paredes EP, Flores-Flores LF, Garcia-Rejon JE, Diaz FJ, Blitvich BJ, Andrade-Narvaez M, Jimenez-Rios E, Blair CD, Olson KE, Black WT, Beaty BJ, 2004. Introduction of the American/Asian genotype of dengue 2 virus into the Yucatan State of Mexico. Am J Trop Med Hyg 71: 485–492.[Abstract/Free Full Text]
  45. Thomas SJ, Strickman D, Vaughn DW, 2003. Dengue epidemiology: virus epidemiology, ecology, and emergence. Adv Virus Res 61: 235–289.[Medline]
  46. Beasley D, Davis CT, Estrada-Franco J, Navarro-Lopez R, Campomanes-Cortes A, Tesh RB, Weaver SC, Barrett ADT, 2004. Genome sequence and attenuating mutations in West Nile virus isolate from Mexico. Emerg Infect Dis 10: 2221–2224.[Medline]
  47. Davis CT, Beasley DW, Guzman H, Siirin M, Parsons RE, Tesh RB, Barrett AD, 2004. Emergence of attenuated West Nile virus variants in Texas, 2003. Virology 330: 342–350.[Medline]
  48. Blitvich BJ, Fernandez-Salas I, Contreras-Cordero JF, Lorono-Pino MA, Marlenee NL, Diaz FJ, Gonzalez-Rojas JI, Obregon-Martinez N, Chiu-Garcia JA, Black WC, Beaty BJ, 2004. Phylogenetic analysis of West Nile virus, Nuevo Leon State, Mexico. Emerg Infect Dis 10: 1314–1317.[ISI][Medline]
  49. Elizondo-Quiroga D, Davis CT, Fernandez-Salas I, Escobar-Lopez R, Olmos DV, Gastalum LCS, Acosta MA, Elizondo-Quiroga A, Gonzales-Rojas JI, Cordero JFC, Guzman H, Travassos da Rosa A, Blitvich BJ, Barrett ADT, Beaty BJ, Tesh RB, 2005. West Nile virus isolation in human and mosquitoes, Mexico. Emerg Infect Dis 11:1449–1452.[Medline]




This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via ISI Web of Science (2)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by FARFÁN-ALE, J. A.
Right arrow Articles by BEATY, B. J.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by FARFÁN-ALE, J. A.
Right arrow Articles by BEATY, B. J.
Related Collections
Right arrow West Nile

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS