LETTERS

4. Kapczynski DR, Gonder E, Liljebjelke K, Oropouche Fever washing the wells, 100 μL of serum Lippert R, Petkov D, Tilley B. Vaccine- diluted 1:400 was added into infected induced protection from egg production Outbreak, Manaus, losses in commercial turkey breeder hens and uninfected wells. After incubation following experimental challenge with a Brazil, 2007–2008 and washing the wells, a peroxidase- triple-reassortant H3N2 avian infl uenza conjugated goat anti-human IgM was . Avian Dis. 2009;53:7–15. DOI: To the Editor: Oropouche virus added; fi nally, the ABTS substrate 10.1637/8199-122707-Reg.1 (OROV) is an , Orthobu- (KPL, Inc., Gaithersburg, MD, USA) 5. Spackman E, Senne DA, Myers TJ, Bulaga nyavirus, transmitted among , LL, Garber LP, Perdue ML, et al. Devel- was added into the wells. The plates opment of a real-time reverse transcriptase marsupials, primates, and birds by the were incubated and read on a spec- PCR assay for type A infl uenza virus and mosquitoes serratus and Culex trophotometer at 405 nm. The cutoff the avian H5 and H7 hemagglutinin sub- quinquefasciatus. Notably, this virus for the test was determined to be the types. J Clin Microbiol. 2002;40:3256–60. has adapted to an urban cycle involving DOI: 10.1128/JCM.40.9.3256-3260.2002 mean of optical densities read in all 6. Senne DA. Annual reports on National man, with midges (Culicoides paraen- wells containing uninfected cells plus Veterinary Services Laboratories avian sis) as the main vector (1). Oropouche 3 standard deviations. infl uenza and Newcastle disease virus fever is the second most frequent ar- Of the 631 patients in the study, diagnostics. Proceedings of the Unit- boviral disease in Brazil, surpassed ed States Animal Health Association. 128 (20.3%) had IgM to 2006;110:634–7. only by dengue. OROV causes large, OROV. The age range was 2–81 years 7. Thomas C, Manin TB, Andriyasov explosive outbreaks of acute febrile (mean 29.5 ± 14 years), and 77 (60.2%) AV, Swayne DE. Limited susceptibil- illness in cities and villages in the Am- were women or girls. Most of the cas- ity and lack of systemic by an azon and central regions of Brazil. An H3N2 swine infl uenza virus in intrana- es occurred November through March sally inoculated chickens. Avian Dis. estimated 500,000 cases of OROV in- during the rainy season. In addition 2008;52:498–501. DOI: 10.1637/8210- fection have occurred in Brazil in the to fever, the patients had headache 011408-RESNOTE.1 past 48 years. In addition to outbreaks, (93 [72.7%]), myalgia (90 [70.3%]), 8. Yassine HM, Al Natour MQ, Lee C, Saif OROV can also cause sporadic human YM. Interspecies and intraspecies trans- and arthralgia (74 [57.8%]). Rash was mission of triple reassortant H3N2 infl u- (2). observed in 54 patients (42.2%), and enza A . Virol J. 2007;4:129. DOI: The Tropical Medicine Founda- hemorrhagic phenomena (petechiae, 10.1186/1743-422X-4-129 tion of Amazonas State (TMF-AM) epistaxis, and gingival bleeding) were 9. Choi YK, Lee JH, Erickson G, Goyal SM, is a tertiary care center specializing Joo HS, Webster RG, et al. H3N2 infl u- observed in 20 patients (15.5%). All enza virus transmission from swine to in tropical and infectious diseases and patients recovered without sequelae turkeys, United States. Emerg Infect Dis. is located in the city of Manaus. Syn- and were not hospitalized. 2004;10:2156–60. dromic surveillance for acute febrile Despite the knowledge of the oc- 10. Senne DA. Avian infl uenza in North and illness has been conducted by TMF- South America, the Caribbean, and Aus- currence of several in the tralia, 2006–2008. Avian Dis. 2009. In AM since 1998. During January 2007 Amazon region, most cases of arbo- press. through November 2008, we obtained viral diseases remain undiagnosed, samples from 631 patients who probably because of their generally Address for correspondence: David E. Swayne, had acute febrile illness for ≥5 days mild and self-limited clinical mani- Southeast Poultry Research Laboratory, but who had negative results at ini- festations. Patients usually recover Agricultural Research Service, US Department tial screening for malaria (thick blood completely after a couple of days. of Agriculture, 934 College Station Rd, Athens, smear) and dengue (MAC-ELISA). However, even more severe cases GA 30605, USA; email: david.swayne@ars. Blood samples were tested for OROV may remain undiagnosed, especially usda.gov immunoglobulin (Ig) M antibodies by because of long distances to health an indirect enzyme immune assay us- care facilities, diffi culties in sample ing infected cells as antigen, as previ- transportation, and lack of laboratory ously reported for dengue (3). The opinions expressed by facilities capable of conducting the di- For the indirect enzyme immune authors contributing to this agnostic assays. With regard to OROV assay using infected cells as antigen, infections, diagnosis of OROV may journal do not necessarily refl ect C6/36 A. albopictus cells were grown be easily confused with other acute the opinions of the Centers for in 96 well microplates; these cells febrile illness, including malaria and Disease Control and Prevention were infected with OROV (BeAn 1991 dengue, both of which are highly en- or the institutions with which the strain). After 4 days, the cells were demic in Manaus. fi xed in the wells with 7% formalin authors are affi liated. In the present study, an inhouse buffered at pH 7.0. The microplate was enzyme immune assay for IgM using blocked with 5% skim milk and, after infected cell culture as antigen was

Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 15, No. 12, December 2009 2063 LETTERS found suitable for the diagnosis of nologic Development (CNPq – grant aria PC, et al. Oropouche fever OROV infections in the acute phase. 484941/2007-0) and by the Amazonas in northern Brazil: epidemiology and mo- lecular characterization of isolates. J Clin Thus, a combination of a systematic Foundation for Research Support. Virol. 2009;44:129–33. DOI: 10.1016/j. surveillance for acute febrile illnesses jcv.2008.11.006 and effi cient laboratory diagnosis for Maria Paula G. Mourão, 7. Figueiredo LT. Emergent arboviruses OROV resulted in the discovery of an in Brazil. Rev Soc Bras Med Trop. Michelle S. Bastos, 2007;40:224–9. DOI: 10.1590/S0037- outbreak, which would probably have João Bosco L. Gimaque, 86822007000200016 been overlooked if it had occurred in Bruno Rafaelle Mota, 8. Nunes MR, Martins LC, Rodrigues any region simultaneously with large Giselle S. Souza, SG, Chiang JO, Azevedo Rdo S, da dengue outbreaks or in the absence Rosa AP, et al. Oropouche virus isola- Gustavo Henrique N. Grimmer, tion, southeast Brazil. Emerg Infect Dis. of laboratory diagnosis. The cases of Elizabeth S. Galusso, 2005;11:1610–3. OROV fever reported here likely rep- Eurico Arruda, 9. Felippe-Bauer ML, Caceres AG, Silva CS, resent a small portion of the cases; a and Luiz Tadeu M. Figueiredo Valderrama-Bazan W, Gonzales-Perez A. much higher number of cases prob- Two new Culicoides of the paraensis spe- Author affi liations: Tropical Medicine Foun- cies group (Diptera: Ceratopogonidae) ably occurred in Manaus during the dation of Amazonas State, Manaus, Bra- from the Amazonian region of Peru. Mem study period. zil (M.P.G. Mourão, M.S. Bastos, J.B.L. Inst Oswaldo Cruz. 2003;98:1051–8. DOI: 10.1590/S0074-02762003000800014 The clinical characteristics of Gimaque, E.S. Galusso); Amazonas State most cases of OROV fever in this University, Manaus (M.P.G. Mourão, J.B.L. Address for correspondence: Maria Paula G. outbreak were similar to previously Gimaque, B.R. Mota); Nilton Lins Univer- Mourão, Tropical Medicine Foundation of reported descriptions of the illness. sity Center, Manaus (M.P.G. Mourão, E.S. Amazonas (Laboratory of ), Av Pedro Notably, however, 20 (15.5%) pa- Galusso); Leonidas and Maria Deane Teixeira, 25, Manaus, Amazonas, Brazil 69040- tients from Manaus had spontaneous Research Center, Manaus (G.S. Souza, 000; email: [email protected] hemorrhagic phenomena (petecchiae, G.H.N. Grimmer); and University of São epistaxis, and gingival bleeding) that Paulo School of Medicine, Ribeirão Preto, had not previously been described in Brazil (E. Arruda, L.T.M. Figueiredo) OROV fever (4–6). Moreover, symp- toms of involvement of the central DOI: 10.3201/eid1512.090917 nervous system were not observed. In recent years, the area of cir- References culation and the epidemic potential 1. Pinheiro FP, Hoch AL, Gomes ML, Rob- Identical Strains of of OROV have increased, and this erts DR. Oropouche virus. IV. Laboratory virus has emerged as a public health transmission by Culicoides paraensis. Am Borrelia hermsii in problem in Brazil and other countries J Trop Med Hyg. 1981;30:172–6. Mammal and Bird in the Americas. Presently, OROV 2. Bernardes-Terzian AC, Bronzoni RVM, Drumond BP, Silva-Nunes M, Silva To the Editor: On August 5, is the most common of the Brazilian NS, Urbano-Ferreira M, et al. Sporadic zoonotic arboviruses infecting humans oropouche virus infection, acre, Brazil. 1994, a northern spotted owl, Strix (7). Further evidence of the spread of Emerg Infect Dis. 2009;15:348–50. DOI: occidentalis caurina, was found OROV was its isolation in 2003 from 10.3201/eid1502.080401 dead in Kittitas County, Washington, 3. Figueiredo LT, Shope RE. An enzyme im- USA (1). A thorough investigation a small primate, a marmoset (Cal- munoassay for dengue using in- lithrix), in the state of Minas Gerais in fected cultured cells as antigen. and necropsy identifi ed the probable southeast Brazil, far from the Amazon J Virol Methods. 1987;17:191–8. DOI: cause of death to be a spirochete in- region (8). Considering that midges 10.1016/0166-0934(87)90129-7 fection. The organisms were seen in 4. Pinheiro FP, Travassos da Rosa AP, Tra- sections of the bird’s liver with use of (Culicoides paraensis) occur in most vassos da Rosa JF, Ishak R, Freitas RB, low altitude areas of the Americas, it Gomes ML, et al. Oropouche virus. I. A modifi ed Steiner silver stain and mi- is conceivable that environmental de- review of clinical, epidemiological, and croscopy. DNA was extracted from struction and climate changes could ecological fi ndings. Am J Trop Med Hyg. the infected liver, and PCR–DNA se- 1981;30:149–60. quencing of the 16S ribosomal RNA result in OROV outbreaks in the large 5. Watts DM, Lavera V, Callahan J, Rossi C, cities of Brazil, as well as in other parts Oberste MS, Roehrig JT, et al. Venezuelan (rRNA) locus identifi ed the bacterium of the Western Hemisphere (9). equine and Oropouche virus as a relapsing fever spirochete related infections among Peruvian army troops most closely to Borrelia hermsii (1). in the Amazon region of Peru. Am J Trop The lack of additional data surround- This research was supported by the Med Hyg. 1997;56:661–7. 6. Vasconcelos HB, Azevedo RS, Casseb ing this case precluded Thomas et al. National Council for Scientifi c and Tech- SM, Nunes-Neto JP, Chiang JO, Cantu- from concluding that this spirochete

2064 Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 15, No. 12, December 2009