Recent occurence of human infection by Rocio arbovirus in Ribeira Valley, Brazil

Abstract

The presence of IgM antibodies to Rocio in sera of two children from rural area of Ribeira Valley, Brazil, was detected by MAC-ELISA. This new arbovirus of the Flaviviridae family was responsible for an extensive encephalitis epidemic that occurred in the region in 1975-1977. Since 1980 no human disease caused by this virus has been diagnosed. An improvement on surveillance of Rocio infections and on the researches for virus identification in suspected vectors and reservoirs is necessary.

A Saint Louis encephalitis and Rocio virus serosurvey in Brazilian horses

“…In South America, Saint Louis encephalitis virus (SLEV) and Rocio virus (ROCV), which are both fl aviviruses that are closely related to the Japanese encephalitis serocomplex viruses, can produce human encephalitis 4,5 . ROCV was fi rst isolated from a fatal human case during an epidemic of encephalitis in Ribeira Valley in the southeastern region of the State of São Paulo, Brazil, in 1975 6 . This ROCV epidemic involved over 1,000 reported cases with a 10% fatality rate and sequelae in 20% of the cases 2 .…”

Rocio Virus: An Updated View on an Elusive Flavivirus

“…Subsequent to the 1975-1977 outbreak, there was a precipitous decrease in the number of cases [58], with two IgM positive cases in school children reported in 1987 [15] and 6 IgG positive cases in residents at the Juréia-Itatins Ecological Station in 1990 [59] (Table 1). Interestingly, in a 1984 arbovirus serosurvey of 288 rural inhabitants in the state of Bahia, 4.3% were positive to arbovirus exposure, with a 12 year-old schoolgirl positive to ROCV with no previous travel history outside the state [60].…”

“…Nine ROCV strains were also recovered from CNS tissues of 17 other patients who died with encephalitis [2], sentinel mice [2], an Andean sparrow (Zonotrichia capensis) [2] a pool of Psorofora ferox [8], and partial virus fragments were detected bio-banked human sera collected during an outbreak of dengue fever in Goiânia in 2011 [9]. Subsequent serosurveys detected the presence of ROCV-specific antibodies in migratory birds (e.g., double-collared seedeater (Sporophila caerulescens) and creamy-bellied thrush (Turdus amaurochalinus)) [10,11], horses [12], water buffaloes (Bubalus bubalis) [13] and humans [14,15], suggesting undetected ROCV circulation in large geographic areas outside the State of Sao Paulo [9]. Interestingly, attempts at the time to better understand the epidemiology of encephalitis in patients with a history of febrile illness [7] were overshadowed by a widespread epidemic of meningococcal meningitis affecting the state of Sao Paulo, resulting in their misdiagnosis (reviewed in [16]).…”

Flaviviruses as agents of childhood central nervous system infections in Brazil

“…In Brazil, flaviviruses considered neurotropic agents, such as as WNV and Rocio virus, have been described as circulating but without case reports in children [7], [8]. Some other potential neurotropic flaviviruses, including DENV and ZIKV, circulate in epidemics; however, there are few reports of these viruses as aetiological agents of CNS infections in children.…”