Zika Virus Outbreak in Rio de Janeiro, Brazil: Clinical Characterization, Epidemiological and Virological Aspects

Abstract

BackgroundIn 2015, Brazil was faced with the cocirculation of three arboviruses of major public health importance. The emergence of Zika virus (ZIKV) presents new challenges to both clinicians and public health authorities. Overlapping clinical features between diseases caused by ZIKV, Dengue (DENV) and Chikungunya (CHIKV) and the lack of validated serological assays for ZIKV make accurate diagnosis difficult.Methodology / Principal FindingsThe outpatient service for acute febrile illnesses in Fiocruz initiated a syndromic clinical observational study in 2007 to capture unusual presentations of DENV infections. In January 2015, an increase of cases with exanthematic disease was observed. Trained physicians evaluated the patients using a detailed case report form that included clinical assessment and laboratory investigations. The laboratory diagnostic algorithm included assays for detection of ZIKV, CHIKV and DENV. 364 suspected cases of Zika virus disease were identified based on clinical criteria between January and July 2015. Of these, 262 (71.9%) were tested and 119 (45.4%) were confirmed by the detection of ZIKV RNA. All of the samples with sequence information available clustered within the Asian genotype.Conclusions / SignificanceThis is the first report of a ZIKV outbreak in the state of Rio de Janeiro, based on a large number of suspected (n = 364) and laboratory confirmed cases (n = 119). We were able to demonstrate that ZIKV was circulating in Rio de Janeiro as early as January 2015. The peak of the outbreak was documented in May/June 2015. More than half of the patients reported headache, arthralgia, myalgia, non-purulent conjunctivitis, and lower back pain, consistent with the case definition of suspected ZIKV disease issued by the Pan American Health Organization (PAHO). However, fever, when present, was low-intensity and short-termed. In our opinion, pruritus, the second most common clinical sign presented by the confirmed cases, should be added to the PAHO case definition, while fever could be given less emphasis. The emergence of ZIKV as a new pathogen for Brazil in 2015 underscores the need for clinical vigilance and strong epidemiological and laboratory surveillance.

Zika Virus in the Joint of a Patient with Rheumatoid Arthritis

“…ZIKV and CHIKV share similar acute clinical presentation with arthralgia, skin rash, and fever, which also resembles other rheumatic diseases 1,4 . Most relevantly, ZIKV and CHIKV may complicate the clinical condition of rheumatic patients.…”

“…Since 2015, Brazil has experienced a major public health crisis caused by the arboviruses Zika (ZIKV) and Chikungunya (CHIKV), which are circulating along with the dengue virus 1 .…”

One year after the Zika virus outbreak in Brazil: from hypotheses to evidence

“…Of these, 119 laboratory-confirmed cases of ZIKV infection, with rash in 97% of the confirmed cases and only 36% of the cases experienced fever not that lasted more than a day and was reported only once. There was a low frequency of joint swelling (29%) among cases (35) . In Mexico, 99 confirmed cases were identified via the epidemiological surveillance system.…”

“…This differentiates Zika from other arboviral infections, not only by the high frequency (90-100%) of rash, but also by its timing, appearing in the first 72 hours of infection (18) . In the cohort of Brazil et al (35) , symptoms such as fever and joint swelling were infrequent and other symptoms, such as arthralgia and myalgia, were present in ~60% of cases. Hence, laboratory-confirmed cases may not fulfill the criteria required for suspected cases.…”

“…Two other studies, with a greater number of cases, present different frequencies of these symptoms. In a prospective study by Brazil et al (35) , performed in Rio de Janeiro among 262 patients with a history of acute onset rash with or without fever. Of these, 119 laboratory-confirmed cases of ZIKV infection, with rash in 97% of the confirmed cases and only 36% of the cases experienced fever not that lasted more than a day and was reported only once.…”