Seroprevalence of dengue among healthy adults in a rural community in Southern Malaysia: a pilot study

Abstract

BackgroundThe frequency and magnitude of dengue epidemics continue to increase exponentially in Malaysia, with a shift in the age range predominance toward adults and an expansion to rural areas. Despite this, information pertaining to the extent of transmission of dengue virus (DENV) in the rural community is lacking. This community-based pilot study was conducted to establish DENV seroprevalence amongst healthy adults in a rural district in Southern Malaysia, and to identify influencing factors.MethodsIn this study undertaken between April and May 2015, a total of 277 adult participants were recruited from households across three localities in the Sungai Segamat subdistrict in Segamat district. Sera were tested for immunoglobulin G (IgG) (Panbio® Dengue Indirect IgG ELISA/high-titer capture) and immunoglobulin M (IgM) (Panbio®) antibodies. The plaque reduction neutralization test (PRNT) was conducted on random samples of IgG-positive sera for further confirmation. Medical history and a recall of previous history of dengue were collected through interviews, whereas sociodemographic information was obtained from an existing database.ResultsThe overall seroprevalence for DENV infection was 86.6% (240/277) (95% CI: 83–91%). Serological evidence of recent infection (IgM/high-titer capture IgG) was noted in 11.2% (31/277) of participants, whereas there was evidence of past infection in 75.5% (209/277) of participants (indirect IgG minus recent infections). The PRNT assay showed that the detected antibodies were indeed specific to DENV. The multivariate analysis showed that the older age group was significantly associated with past DENV infections. Seropositivity increased with age; 48.5% in the age group of <25 years to more than 85% in age group of >45 years (P < 0.001). No associations with occupation, study site, housing type, comorbidity, educational level, and marital status were observed, although the latter two were statistically significant in the univariate analysis. None of the studied factors were significantly associated with recent DENV infections in the multivariate analysis, although there was a pattern suggestive of recent outbreak in two study sites populated predominately by Chinese people. The majority of infections did not give rise to recognizable disease (either asymptomatic or nonspecific symptoms) as only 12.9% of participants (31/240) recalled having dengue in the past.ConclusionsThe predominantly rural community under study had a very high previous exposure to dengue. The finding of a high proportion of unreported cases possibly due to subclinical infections underscores the need for enhanced surveillance and control methods. This finding also has implications for measuring disease burden, understanding transmission dynamics, and hypothesizing effects on DENV vaccine efficacy and uptake.Electronic supplementary materialThe online version of this article (10.1186/s40249-017-0384-1) contains supplementary material, which is available to authorized users.

High seroprevalence of dengue virus indicates that dengue virus infections are frequent in central and eastern Sudan

“…Approximately 96.8% of the IgG ELISA-positive serum samples contained DENV-neutralising antibodies. This is similar to the results of a recent study in Malaysia where the Panbio IgG Indirect ELISA had a specificity of 100% compared with a neutralisation test [24].…”

“…The high seroprevalence in Port Sudan indicates an almost universal exposure to dengue viruses. The seroprevalence in this town was comparable to that in the South Indian state Tamil Nadu and in several countries in Southeast Asia . The seroprevalence was higher than in other countries in Africa and in the Middle East .…”

“…Two small groups of patients that were not identified by the laboratory tests were neglected: Firstly, a fraction of the IgG‐ and IgM‐positive samples that were excluded could be from individuals with acute secondary infection rather than from late acute primary infection. In a recent study, the fraction of IgM‐positive sera among presumed secondary dengue was less than 10% . Secondly, since dengue IgM can last for several months in the serum, we could not differentiate between acute dengue fever and fever for other reasons in a patient who was infected a few weeks to months ago.…”

Dengue and Chikungunya among Febrile Outpatients in Kinshasa, Democratic Republic of Congo: a cross-sectional study

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“…Our findings suggest that high density, urbanised areas are not necessarily the primary drivers of ongoing epidemics in Sabah, and that factors other than population size may drive the risk in rural areas. Recent studies in other areas of Malaysia have also shown that dengue infection can occur at equivalent rates in both rural and urban areas (37, 38). It could be that the threshold human density required to maintain transmission may be lower than previously thought, although human movement (which may relate to population density) between urban and rural areas is also likely to have influenced the patterns we observed (39, 40).…”