Accepted for/Published in: JMIR Public Health and Surveillance
Date Submitted: Jan 19, 2021
Date Accepted: Jun 21, 2021
Risk Factors Aassociated with Dengue Fever Outbreak in Islamabad, Pakistan: A Case-Control Study
ABSTRACT
Background:
On 23rd Oct 2016, 79 dengue fever cases were reported from the Union Council (UC) Tarlai to Federal Disease Surveillance and Response Unit Islamabad. A team was deputed to investigate the suspected dengue outbreak.
Objective:
This study was aimed to determine the extent of the outbreak and identify the possible risk factors.
Methods:
Active case finding was conducted through house-to-house survey. A case was defined as, an acute onset of Fever ≥ 38 ℃ in a resident of Tarlai from Oct 2-Nov 11, 2016, with a positive NS-1 test, and any two of following signs and symptoms; retro-orbital/ocular pain, headache, rash, myalgia, arthralgia and hemorrhagic manifestations. A structured questionnaire was used to collect data. Age and sex-matched controls (1:1) were identified from the same area. Blood samples were taken and sent to the National Institute of Health for genotype identification.
Results:
During the active case search, 145 cases of dengue fever were identified by surveying 928 houses from 23rd Oct to 11th Nov, 2016. Attack rate (AR) was 17.0/10,000 population. The mean age was 34.4±14.4 years. More than half of cases were male (n=80, 55.2%). Among all cases, 29% belong to 25-34 years age group while highest attack rate was found in 35-44 years (AR 35.6/10,000) followed by 55-64 year (AR 35.5/10,000). All five blood samples tested positive for NS-1 (genotype DENV-2). Most frequent presenting sin/symptom was fever and headache (100%). Stagnant water around houses (OR = 4.86, CI: 2.94 -8.01, P<0.0001), presence of flower pots in home (OR = 2.73, CI: 1.67-4.45, P<0.0001) and open water container (OR 2.24, CI: 1.36-3.60, P<0.0001) showed higher odds among cases. While. use of bed nets (OR 0.44, CI: 0.25-0.77, P 0.003), insecticidal spray (OR 0.33, CI: 0.22-0.55, P<0.0001), door screening (OR 0.27, CI: 0.15-0.46, P<0.0001), use of mosquito coil/mat (OR 0.26, CI: 0.16-0.44, P<0.0001) and cleanliness in house (OR 0.12, CI: 0.05-0.26, P<0.0001) showed a significant protective effect.
Conclusions:
Stagnant water acting as breeding grounds for vector was probable cause of spread of the outbreak. Establishment of surveillance and early reporting system and use of protective measures against the vector are strongly recommended. Clinical Trial: Not applicable
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