A Comprehensive Study of Dengue Epidemics and Persistence of Anti-Dengue Virus Antibodies in District Swat, Pakistan

Background: Dengue fever is one of the most common human arbovirus infections worldwide. In Pakistan, dengue initially became endemic in the big cities and then expanded to remote areas of the country. The current study reports the dengue epidemics, anti-DENV antibodies prevalence during the active and post-dengue infection, risk factors, disease symptoms, and spotting dengue infection densities in district Swat of Pakistan. Methods: Clinical signs and demographic data of dengue suspected individuals were collected at the time of screening through non-structural protein-1 antigen detection test during 2013-2015. Moreover, selected dengue confirmed individuals were screened for the presence of anti-dengue immunoglobulin (Ig) M and G during the active infection period and post-dengue infection. Results: A total of 8,770 individuals were infected with dengue in 2013 with 36 (0.41%) case fatalities, 307 in 2014 with no case fatality, and 13 in 2015 with no case fatality. The number of male and female cases were 6,139 and 2,631 in 2013, 183 and 124 in 2014, and only 10 and 3 in 2015, respectively. Among all the localities, Tehsil Babozai, an urban setting, reported the highest number of dengue patients during all the study years, that is, 7,673 (87.49% of the total cases) in 2013, 294 (95.76% of the total cases) in 2014, and 13 (100% cases) in 2015. Among 6 age groups, 21-30 years was found to be highly infected in 2013 (37.13% of all cases) and 2014 (33.55%). Furthermore, 1,231 (21.94% of all cases) had IgM antibodies and 71 (1.26%) had IgG antibodies in 2013, 78 (26% of all cases) had IgM antibodies and 7 (2.33%) had IgG antibodies in 2014, and only 4 (30.76%) patients had IgM and 0 (0%) had IgG antibodies in 2015. Furthermore, urban areas had the highest infection density in district Swat. The majority of the patients in rural areas had a traveling history to the urban areas before their illness. Conclusion: To sum up, male gender, young individuals, and those living in urban areas were at the greater risk of dengue infection.