Epidemic dengue transmission in southern Sumatra, Indonesia

Abstract

An outbreak of dengue fever (DF), dengue haemorrhagic fever (DHF), and dengue shock syndrome (DSS) in the city of Palembang, south Sumatra, Indonesia was investigated to (i) validate epidemic occurrence, (ii) confirm dengue virus aetiology and associated serotype(s), (iii) provide a demonstrable measure of community impact, and (iv) identify causative relationship (if any) with climatic El Niño Southern Oscillation (ENSO) influences. Trend analysis based on a 6-year retrospective review of hospital records demonstrates a 3-fold increase in clinical cases for the outbreak period (January-April 1998), relative to historical records. In the 2 hospitals surveyed, the monthly mean number of outbreak-related dengue cases over 4 months was 833 (range 650-995 cases/month); the mean monthly value for the previous 72 months was 107 (range 14-779 cases/month). An apparent trend in epidemic transmission was observed, evolving from a 5-year cyclic phenomenon to an annual occurrence, often indistinguishable from one year to the next. The proportional distribution of clinical outbreak cases into DF, DHF and DSS diagnostic categories was 24%, 66%, and 10%, respectively. The population aged 10-19 years accounted for the largest (35%) proportion of hospitalized DHF cases, followed by children aged 5-9 years (25%) and children aged 4 years (16%). Serum samples obtained during acute illness from 221 hospitalized patients were examined using serology, RT-PCR, and virus isolation in cell culture: 59% of samples had laboratory evidence of a dengue infection. All 4 dengue virus serotypes (DEN 1-4) were identified in epidemic circulation, with DEN 3 predominating (43%). DEN 1 was the principal serotype associated with less severe dengue illness, suggesting that virulence may be, in part, a function of infecting serotype. The climatic influence of ENSO on rainfall and temperature in the months leading up to and during the outbreak was dramatic, and is likely to contribute to favourable outbreak conditions.

Correlation of disease spectrum among four Dengue serotypes: a five years hospital based study from India

“…In congruence with the present study, Corwin et al 25 also found that Den-1 is associated with less severe disease. Several reports from other countries articulating differences in disease severity associated with distinct dengue serotypes support our results.…”

Transmission of Epidemic Dengue Hemorrhagic Fever in Easternmost Indonesia

“…5 This was also evident during the 1993-1994 outbreak reported from Papua, although DEN-1 and DEN-2 viruses were also detected.…”

“…9 The implication as to the predominance of DEN-3 virus in association with DHF was documented in other instances of epidemic DHF occurrences in Indonesia, including the Palembang and Jayapura outbreak. 4,5 The predominance of DEN-3 virus in this and other outbreak findings throughout Indonesia may represent a sampling bias because most specimen collections have targeted inpatient populations who present more severe clinical hemorrhagic manifestations. While there may indeed be a virulence component associated with an infecting viral serotype, it is also recognized that other serotypes may be more prevalent among less severe cases.…”

“…Similarly, with a decrease in average accu- As reported from the outbreak investigations in Jayapura in 1993, and in Palembang, South Sumatra in 1998, the largest proportion of recognized dengue cases were found in the population less than 15 years of age. 4,5 The near equal representation of male and female cases in the segment of the population less than 15 years old contrasted significantly with Acute cases † (n ‫ס‬ 15) 27% 33.3% (all dengue -3) Convalescing cases ‡ (n ‫ס‬ 37) 30% ND Controls § (n ‫ס‬ 32) 3% ND * ELISA ‫ס‬ enzyme-linked immunosorbent assay; PCR ‫ס‬ polymerase chain reaction; ND ‫ס‬ not done.…”

Dengue in Southeast Asia: epidemiological characteristics and strategic challenges in disease prevention

“…This is a problem that needs to be addressed since adult disease is not just confined to travelers from developed countries. In Southeast Asia, dengue primarily affects the adult population in Singapore 39,40 , while the average age of infection has been observed to be increasing in other places 41,42 . Notwithstanding the current debate over the WHO case definition, there is also no consistency in the way these definitions are applied across dengue-endemic countries.…”