Oropouche fever epidemic in Northern Brazil: epidemiology and molecular characterization of isolates.
BACKGROUND
Oropouche fever virus is an important arbovirus associated with febrile disease that re-emerged in 2006 in several municipalities of Pará State, Bragantina region, Amazon, Brazil, 26 years after the last epidemic.


OBJECTIVE
To investigate an Oropouche fever outbreak in this region.


METHODS
A serologic survey and prospective study of acute febrile cases were performed in Magalhães Barata (urban and rural areas) and Maracanã (rural area) municipalities. Serology (IgM-ELISA and hemagglutination-inhibition [HI]), virus isolation, RT-PCR and real-time-PCR were used to confirm Oropouche virus (OROV) as responsible for the febrile outbreaks.


RESULTS
Real-time-PCR showed high titers of OROV in acute-phase serum samples from febrile patients. From 113 of 119 acutely febrile patients with paired serum samples, OROV infections was confirmed by serologic conversion (n=76) or high titers (n=37) for both HI and IgM-ELISA. Patients had a febrile disease characterized by headache, chills, dizziness, photophobia, myalgia, nausea, and vomiting. Females and children under 15 years of age were most affected. Nucleotide sequencing of six OROV isolates identified that genotype II was associated with the human disease epidemic.


CONCLUSIONS
Oropouche fever, which has re-emerged in the Bragantina region in eastern Amazon 26 years after the last epidemic, is caused by genotype II, a lineage previously found only in Peru and western Brazil.
Vasconcelos
Helena B
HB
Seção de Arbovirologia e Febres Hemorrágicas, Instituto Evandro Chagas/SVS/MS, Belém, Pará State, Brazil.
Azevedo
Raimunda S S
RS
Casseb
Samir M
SM
Nunes-Neto
Joaquim P
JP
Chiang
Jannifer O
JO
Cantuária
Patrick C
PC
Segura
Maria N O
MN
Martins
Lívia C
LC
Monteiro
Hamilton A O
HA
Rodrigues
Sueli G
SG
Nunes
Márcio R T
MR
Vasconcelos
Pedro F C
PF
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000914:Antibodies, Viral / Q000097:blood*; D001938:Brazil / Q000453:epidemiology; D002044:Bunyaviridae Infections / Q000453:epidemiology*; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005838:Genotype; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D016851:Orthobunyavirus / Q000235:genetics* / Q000302:isolation & purification*; D011446:Prospective Studies; D012367:RNA, Viral / Q000097:blood; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D012307:Risk Factors; D055815:Young Adult
D000914:Antibodies, Viral; D007074:Immunoglobulin G; D012367:RNA, Viral