Arboviral etiologies of acute febrile illnesses in Western South America, 2000-2007.
BACKGROUND
Arthropod-borne viruses (arboviruses) are among the most common agents of human febrile illness worldwide and the most important emerging pathogens, causing multiple notable epidemics of human disease over recent decades. Despite the public health relevance, little is know about the geographic distribution, relative impact, and risk factors for arbovirus infection in many regions of the world. Our objectives were to describe the arboviruses associated with acute undifferentiated febrile illness in participating clinics in four countries in South America and to provide detailed epidemiological analysis of arbovirus infection in Iquitos, Peru, where more extensive monitoring was conducted.


RESULTS
A clinic-based syndromic surveillance system was implemented in 13 locations in Ecuador, Peru, Bolivia, and Paraguay. Serum samples and demographic information were collected from febrile participants reporting to local health clinics or hospitals. Acute-phase sera were tested for viral infection by immunofluorescence assay or RT-PCR, while acute- and convalescent-phase sera were tested for pathogen-specific IgM by ELISA. Between May 2000 and December 2007, 20,880 participants were included in the study, with evidence for recent arbovirus infection detected for 6,793 (32.5%). Dengue viruses (Flavivirus) were the most common arbovirus infections, totaling 26.0% of febrile episodes, with DENV-3 as the most common serotype. Alphavirus (Venezuelan equine encephalitis virus [VEEV] and Mayaro virus [MAYV]) and Orthobunyavirus (Oropouche virus [OROV], Group C viruses, and Guaroa virus) infections were both observed in approximately 3% of febrile episodes. In Iquitos, risk factors for VEEV and MAYV infection included being male and reporting to a rural (vs urban) clinic. In contrast, OROV infection was similar between sexes and type of clinic.


CONCLUSIONS
Our data provide a better understanding of the geographic range of arboviruses in South America and highlight the diversity of pathogens in circulation. These arboviruses are currently significant causes of human illness in endemic regions but also have potential for further expansion. Our data provide a basis for analyzing changes in their ecology and epidemiology.
Forshey
Brett M
BM
United States Naval Medical Research Center Detachment, Iquitos and Lima, Peru.
Guevara
Carolina
C
Laguna-Torres
V Alberto
VA
Cespedes
Manuel
M
Vargas
Jorge
J
Gianella
Alberto
A
Vallejo
Efrain
E
Madrid
César
C
Aguayo
Nicolas
N
Gotuzzo
Eduardo
E
Suarez
Victor
V
Morales
Ana Maria
AM
Beingolea
Luis
L
Reyes
Nora
N
Perez
Juan
J
Negrete
Monica
M
Rocha
Claudio
C
Morrison
Amy C
AC
Russell
Kevin L
KL
Blair
Patrick J
PJ
Olson
James G
JG
Kochel
Tadeusz J
TJ
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000914:Antibodies, Viral / Q000097:blood; D001102:Arbovirus Infections / Q000453:epidemiology* / Q000473:pathology / Q000821:virology*; D001103:Arboviruses / Q000145:classification* / Q000302:isolation & purification; D002648:Child; D002675:Child, Preschool; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005335:Fever of Unknown Origin / Q000453:epidemiology* / Q000209:etiology*; D019085:Fluorescent Antibody Technique, Direct; D006801:Humans; D007075:Immunoglobulin M / Q000097:blood; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013020:South America / Q000453:epidemiology; D055815:Young Adult
D000914:Antibodies, Viral; D007075:Immunoglobulin M