Considering co-circulation of different arbovirus in RS, including Dengue virus, CHIKV, and ZIKV, and the presence of Aedes aegypti and Aedes albopictus in the area, surveillance of patients infected by these viruses contributes to the control and prevention of such diseases. Practical difficulties in diagnosing these infections are discussed.

The main symptoms of dengue fever are headache, sudden onset of fever, retro-orbital pain, body aches, nausea and vomiting, joint pains, weakness, and rash. With the recent introduction of Chikungunya virus (CHIKV) and Zika virus (ZIKV) in Brazil in 2014, which infect humans causing symptoms similar to dengue fever, the correct diagnosis of these infections became challenging. Even though laboratory tests have been developed to discriminate among DENV, CHIKV, and ZIKV, these assays might yield confounding results mainly due to cross-reacting antibodies presented by people who had been previously infected or vaccinated against a flavivirus (such as yellow fever). 3 Therefore, diagnosis of these arboviral diseases relies not only Samples that were collected after 6 or more days of onset of symptoms were analyzed by using either the dengue IgM capture | RESULTSFrom January 2014 to December 2016, 13,420 suspected cases of DENV infection were notified in RS, with a total of 3938 positive cases (29.3%). Of these, 3109 were confirmed based on laboratory results, while 829 were considered DENV-positive based on clinical and epidemiological criteria (Table 1). As can be observed in Table 1 Dengue virus 1 was the most prevalent serotype circulating in RS during this period (97.5% of the cases). Although DENV-2, DENV-3, and DENV-4 were also identified, they referred to imported cases, except for 1 autochthonous case of DENV-4 that was confirmed in 2014.Dengue fever occurred mainly in adults, with similar distribution among age groups. Nevertheless, some age groups showed frequencies higher than the statistically expected: in 2014, prevalence was high in the age group 21 to 30 years old, in 2015 in adults older than 41 years old, and in 2016 in the age group 11 to 20 years old (Table 1).There was no difference in prevalence of DENV infection between men and women in the period analyzed (P = .4) ( Table 1). Of note, of all patients investigated, 87 were pregnant women and, of these, 19 were positive for DENV (Table 1).The symptoms most reported by infected patients were fever, myalgia, and headache, followed by retro-orbital pain, nausea, exanthema, and arthralgia; vomiting, leucopenia, and petechia, though less common symptoms, were also reported ( Figure 1A). Data of other clinical conditions were available only in Notification Forms in 2016, and the main one found was hypertension, in 52.6% of the cases;other comorbidities observed were diabetes, hematologic diseases, hepatopathies, chronic kidney disease, and autoimmune disease ( Figure 1B).As expected, the highest incidence of dengue cases in RS occurred | DISCUSSIONDengue virus was introduced into Brazil more than 30 years ago, causing outbreaks in most states. In RS, however, the first notification The results presented herein reinforce that a significant and constant increase in the number of DENV cases is occurring in RS.The recent introduction of CHIKV and ZIKV in the state 15 has posed a concern to the population and health authorities, and this might have c...

No abstract

Chikungunya is a reemerging arthropod-borne virus that has been causing large outbreaks in the Americas. In Brazil, Asian Caribbean and ECSA genotypes have been detected and lead to large outbreaks in several states since 2014. In Rio Grande do Sul (RS), the southernmost State, the first autochthonous cases were reported in 2016. We employed genome sequencing and epidemiological investigation to characterize the increasing CHIKF burden in RS from 2017 to 2021. Distinct lineages of the ECSA genotype were responsible for human infections from 2017 to 2021. Until 2020, CHIKV introductions were most travel associated and transmission was limited. Then, in 2021, the largest outbreak occurred in the state associated with the introduction of a new ECSA lineage. New CHIKV outbreaks are likely to occur in the near future due to abundant competent vectors and a susceptible population, exposing more than 11 million inhabitants to an increasing infection risk.

BACKGROUND Chikungunya is a mosquito-borne virus that has been causing large outbreaks in the Americas since 2014. In Brazil, Asian-Caribbean (AC) and East-Central-South-African (ECSA) genotypes have been detected and lead to large outbreaks in several Brazilian states. In Rio Grande do Sul (RS), the southernmost state of Brazil, the first cases were reported in 2016. OBJECTIVES AND METHODS We employed genome sequencing and epidemiological investigation to characterise the Chikungunya fever (CHIKF) burden in RS between 2017-2021. FINDINGS We detected an increasing CHIKF burden linked to travel associated introductions and communitary transmission of distinct lineages of the ECSA genotype during this period. MAIN CONCLUSIONS Until 2020, CHIKV introductions were most travel associated and transmission was limited. Then, in 2021, the largest outbreak occurred in the state associated with the introduction of a new ECSA lineage. CHIKV outbreaks are likely to occur in the near future due to abundant competent vectors and a susceptible population, exposing more than 11 million inhabitants to an increasing infection risk.