Dengue, also known as "tropical flu," is a viral disease transmitted to humans by Aedes mosquito. 1 Dengue fever is a deadly arboviral disease caused by any of the five serotypes DENV1, DENV2, DENV3, DENV4 and DENV5 which are placed in the Family Flaviviridae and genus Flavivirus. 2 Each serotype of the virus produces a specific, lifelong immunity, but it provides only a short term cross-immunity. 3 This illness ranges from a mild asymptomatic form to severe dengue hemorrhagic fever (DHF) with or without dengue shock syndrome (DSS). 4

An estimated 50 million dengue infections occur worldwide annually, the South-East Asia Region (SEAR) and Western Pacific regions are most seriously affected with detection of all four serotypes of dengue. 5 Between 2006 and 2012, National Vector Borne Disease Control Programme (NVBDCP), in India, reported an average annual number of 20,474 dengue cases while in 2019 Maharashtra state alone reported 19034 dengue cases 6, 7 however estimates of the average annual number varies to an apparent case of 33 million. 8 The National Vector Borne Diseases Control Program (NVBDCP) is an integral part of the National Rural Health Mission (NRHM) of India and aims for prevention & control of vector borne diseases like Malaria, Dengue, Chikungunya, Japanese Encephalitis (JE), Kala-azar and Lymphatic filariasis. The GoI plans to ensure right diagnostics and treatment of the aforementioned vector borne diseases to all people living in rural/urban/tribal areas via this program.

Dengue was reclassified by WHO in 2009 according to levels of severity as, dengue without warning signs, dengue with warning signs like abdominal pain, persistent vomiting, fluid accumulation, mucosal bleeding, lethargy, liver enlargement, increasing hematocrit with decreasing platelets, and severe dengue which included dengue with severe plasma leakage, severe bleeding, or organ failure. 9 Hence, there is a need for early diagnosis of dengue infection since it can prevent fatal cases.

The primary objective of this retrospective analytic study was to determine the seropositivity of dengue and to observe the changing trend of the disease over the past 10 years in and around Akola district.

This hospital based retrospective study was carried out in the Department of Microbiology, at a tertiary care hospital in Akola, Maharashtra from January 2015 to April 2024 after ethical approval from the Institutional Ethical Committee. Study group consisted of clinically suspected cases of dengue infection admitted in this hospital, those who attended outpatient department (OPD) and various primary health centres of Akola, Buldhana and Washim districts of Maharashtra. A detailed history was obtained of all the suspected cases in a written format.

As IgM antibody starts appearing after 5 days of infection, 9 instructions were given at the hospital and the peripheral centres to collect the blood sample of suspected patients after 5 days of onset of fever and send to Department of Microbiology for further processing and testing, where serum was separated as per the standard guidelines. 10, 11 The serum samples were subjected to dengue IgM antibody detection by ELISA technique (NIV DEN IgM Capture ELISA kit, NIV-Pune, India). Testing as well as OD cutoff value was determined as per manufacturer’s instructions.

All the testing was performed as a sentinel surveillance hospital/laboratory under the National Vector Borne Disease Control Programme (NVBDCP).

Data was analysed using statistical package for social sciences version 16 (SPSS V16). Observations were presented as frequency and percentage distribution.

Total 13,554 serum samples from suspected dengue cases were collected and subjected to dengue IgM antibody detection by MAC ELISA technique. Out of the total samples tested, 2092 (15.43%) samples were positive for dengue IgM antibody. Prevalence of dengue in suspected cases was found to be 15.43% as shown in the following Table 1.

Maximum number of MAC ELISA positive cases, 628 (30.00%) were in the age group of 11-20 years followed by 519 (24.80%) cases in the age group of 21-30 years as depicted in following Table 2.

Out of the 2092 MAC ELISA positive dengue cases, 1209 (57.80%) were males and 883 (42.20%) were females as shown in Figure 1.

Maximum number MAC ELISA positive cases were reported in the months of November followed by October followed by September followed by August as depicted in following Table 3.

From our study we conclude that over the past decade, dengue positivity has increased in this area and post-monsoon months specifically show an overall rise in cases. As far as clinical scenario is concerned, a high suspicion of dengue should be considered in cases with high grade fever, myalgia, and arthralgia. Vigilant Surveillance as well as timely laboratory testing is prerequisite for early detection of an impending outbreak and initiate timely preventive and control measures. Active participation of both public and private sector with rapid response will help in reducing the disease burden in the area.