Clinical, epidemiological and virological features of Dengue virus infections in Vietnamese patients presenting to primary care facilities with acute undifferentiated fever

Abstract

Objectives: To explore clinical and virological characteristics and describe the epidemiology of dengue in patients who presented with acute undifferentiated fever (AUF) at primary health centers (PHC) in Binh Thuan Province, Vietnam.

Methods: A prospective observational study was conducted from 2001 to 2006 to study the aetiology in AUF patients. Demographic and clinical information was obtained, and dengue polymerase chain reaction (RT-PCR) and serology were performed on a random selection of patients.

Results: Three hundred fifty-one serologically confirmed dengue patients including 68 primary and 283 secondary infections were included in this study. In 25% (86/351) dengue virus (DENV) was detected by RT-PCR among which 32 DENV-1, 16 DENV-2, 1 DENV-3 and 37 DENV-4 were identified. The predominant dengue serotype varied by year with seasonal fluctuation: DENV-4 in 2001-2002, DENV-1 and DENV-2 from 2003 to 2006. Primary dengue was more common in children. Higher viraemia levels (P=0.010) were found in primary infections compared to secondary infections. DENV-1 infected patients had higher viraemia levels than DENV-2 (P=0.003) and DENV-4 (P<0.001) infected patients. Clinical symptoms were often seen in adults. Few differences in clinical symptoms were found between primary and secondary infection and no significant differences in clinical symptoms between the serotypes were observed.

Conclusions: Our data provide insight in the epidemiology, clinical profile and virological features of mild symptomatic dengue patients who presented to PHC with AUF in Vietnam.

Figure 1

Co-occurrence of multiple dengue virus serotypes in Binh Thuan from 2001 to 2006.

Figure 2

Age group distribution of serologically (n = 1938) and RT-PCR (n = 86) confirmed dengue virus infection and serotypes among AUF patients in Binh Thuan province, 2001–2006.

Figure 3

Distribution of viraemia levels in: (A) patients with primary and secondary dengue infections; (B) patients with primary and secondary dengue infection and fever history; (C) patients with DENV-1, DENV-2, DENV-3 and DENV-4 infections; (D) patients with and without NS1 antigen. All comparison within groups was performed using Mann–Whitney tests. Box plots show median values (horizontal line in the box), 25–75% interquartile range (lower-upper limits of the box), 90% range of data (additional bars), and outliers (circles).