Virus-Specific Differences in Rates of Disease during the 2010 Dengue Epidemic in Puerto Rico

Abstract

BackgroundDengue is a potentially fatal acute febrile illness (AFI) caused by four mosquito-transmitted dengue viruses (DENV-1–4) that are endemic in Puerto Rico. In January 2010, the number of suspected dengue cases reported to the passive dengue surveillance system exceeded the epidemic threshold and an epidemic was declared soon after.Methodology/Principal FindingsTo characterize the epidemic, surveillance and laboratory diagnostic data were compiled. A suspected case was a dengue-like AFI in a person reported by a health care provider with or without a specimen submitted for diagnostic testing. Laboratory-positive cases had: (i) DENV nucleic acid detected by reverse transcriptase-polymerase chain reaction (RT-PCR) in an acute serum specimen; (ii) anti-DENV IgM antibody detected by ELISA in any serum specimen; or (iii) DENV antigen or nucleic acid detected in an autopsy-tissue specimen. In 2010, a total of 26,766 suspected dengue cases (7.2 per 1,000 residents) were identified, of which 46.6% were laboratory-positive. Of 7,426 RT-PCR-positive specimens, DENV-1 (69.0%) and DENV-4 (23.6%) were detected more frequently than DENV-2 (7.3%) and DENV-3 (<0.1%). Nearly half (47.1%) of all laboratory-positive cases were adults, 49.7% had dengue with warning signs, 11.1% had severe dengue, and 40 died. Approximately 21% of cases were primary DENV infections, and 1–4 year olds were the only age group for which primary infection was more common than secondary. Individuals infected with DENV-1 were 4.2 (95% confidence interval [CI]: 1.7–9.8) and 4.0 (95% CI: 2.4–6.5) times more likely to have primary infection than those infected with DENV-2 or -4, respectively.Conclusions/SignificanceThis epidemic was long in duration and yielded the highest incidence of reported dengue cases and deaths since surveillance began in Puerto Rico in the late 1960's. This epidemic re-emphasizes the need for more effective primary prevention interventions to reduce the morbidity and mortality of dengue.

Case Series of Fatal Leptospira spp./Dengue Virus Co-Infections—Puerto Rico, 2010–2012

“…All blood and tissue specimens were tested for molecular and serologic evidence of DENV infection as previously described. 9 Polymerase chain reaction (PCR) with primers specific for Leptospira spp. 26 and microscopic agglutination test (MAT) 27 were performed on all blood specimens.…”

“…1,6 Puerto Rico is a United States territory located in the Caribbean, and in 2010 had a population of 3.7 million residents. 7 Although dengue is a common cause of AFI in Puerto Rico, 8,9 the incidence of leptospirosis 10 is unclear because of underreporting and lack of routine diagnostic testing. 11 Identification of leptospirosis cases through diagnostic testing of suspected dengue cases 12 has enabled detection of concurrent epidemics.…”

Superensemble forecasts of dengue outbreaks

“…There are an estimated 360 million dengue infections per year, approximately 25% of which lead to apparent symptoms ranging from mild fever to life threatening haemorrhagic fever and shock [10]. In Puerto Rico, dengue virus was first isolated in 1963, and all four virus serotypes have been circulating on the island since 1982 [11]. As in the rest of the Americas [12], dengue incidence in Puerto Rico has been increasing over the past two decades, with major outbreaks occurring in 1994, 1998, 2007 and 2010 [11].…”

“…In Puerto Rico, dengue virus was first isolated in 1963, and all four virus serotypes have been circulating on the island since 1982 [11]. As in the rest of the Americas [12], dengue incidence in Puerto Rico has been increasing over the past two decades, with major outbreaks occurring in 1994, 1998, 2007 and 2010 [11]. The annual cost of dengue illness in Puerto Rico has been estimated at $38.7 million, or $10.40 per person [13].…”

Serological Evidence of Infection with Endemic Human Pathogens Among Free-Ranging Old World Monkeys in Puerto Rico

“…2 In PR, dengue and leptospirosis are endemic human diseases and common causes of acute febrile illness. [3][4][5] Dengue virus (DENV) is thought to be exclusively transmitted in a human-mosquito-human cycle. 6,7 However, nonhuman primates are susceptible to DENV infection, and sylvatic nonhuman primate transmission cycles have been described in Africa and Malaysia.…”