Dengue-specific serotype related to clinical severity during the 2012/2013 epidemic in centre of Brazil

Multilingual abstracts:Please see Additional file 1 for translations of the abstract into the five official working languages of the United Nations.Background:Currently,in Brazil,there is a co-circulation of the four dengue(DENV-1 to DENV-4)serotypes.This study aimed to assess whether different serotypes and antibody response patterns were associated with the severity of the disease during a dengue outbreak,which occurred in 2012/2013 in centre of Brazil.Methods:We conducted a prospective study with 452 patients with laboratory confirmed dengue in central Brazil,from January 2012 to July 2013.The clinical outcome was the severity of cases:dengue,dengue with warning signs,and severe dengue.The patients were evaluated at three different moments.Blood sampling for laboratory testing and confirmatory tests for dengue infection were performed.We performed a multinomial analysis considering the three categories of the dependent variable,as outlined above.The odds ratios(ORs)were calculated.A multinomial logistic regression model was applied for variables with a P-value<0.20.Statistical analysis was performed with STATA 12.0 software.Results:Four hundred fifty-two patients(452/632,71.5%)were diagnosed with dengue.The dengue virus(DENV)serotypes were identified in 243 cases.DENV-4 was detected in 135 patients(55.6%),DENV-1 in 91(37.4%),DENV-3 in 13(5.3%),and DENV-2 in 4(1.6%).Patients with the DENV-1 serotype were more prone to present with several clinical and laboratory features as compared with DENV-4 patients,including spontaneous bleeding(P=0.03),intense abdominal pain(P=0.004),neurological symptoms(P=0.09),and thrombocytopenia(P=0.01).Secondary infection was more predominant among DENV-4 cases(80.0%)compared with DENV-1 cases(62.3%)(P=0.03).The univariate analysis showed that females(OR=2.12;95%CI:1.44-3.13;P<0.01)had a higher risk of having dengue with warning signs.The multinomial analysis showed that severe dengue cases with secondary infection had an adjusted OR of 2.80(95%CI:0.78-10.00;P=0.113)as compared with dengue fever with primary infection when adjusted for age and sex.Conclusion:The current data show that 5.8%of patients recruited for treatment in healthcare centres and hospitals during the study period had severe dengue.DENV-4 was the predominant serotype,followed by DENV-1,in a large outbreak of dengue in central Brazil.Our findings contribute to the understanding of clinical differences and immune status related to the serotypes DENV-1 and DENV-4 in central of Brazil.