Dengue Fever (DF) is an arboviral disease caused by the Dengue virus (DENV), and it is a serious public health problem owing to its rapid spread. The most prevalent mosquito vectors for the transmission of the infection are Aedes aegypti and Aedes albopictus [1]. According to a report, DF is estimated to affect 3.9 billion people worldwide and out of which 70% burden exists in Asia [2]. Countries that are worst affected by the DENV are Pakistan, Bangladesh, India, and Sri Lanka [3]. Pakistan is endemic to the DENV for the last 30 years [4]. The first incidence of DF in Pakistan was recorded in Karachi in 1994 [5]. Between 2015 and 2019, there were 90,400 dengue cases and 169 fatalities in Pakistan [4]. Similarly, 3,442 confirmed dengue cases had been reported in 2020 [6]. According to the news, a substantial increase in dengue infections was recorded in the latter 3 months of 2021, with 48,906 cases reported as of November 25, 2021, with 183 fatalities [7, 8].

DF is a single disease that can manifest in a variety of ways, from asymptomatic seroconversion to moderate or severe DF, which can result in shock, severe bleeding, and even death [9, 10]. Dengue hemorrhagic fever (DHF) and Dengue shock syndrome (DSS) are the two most common clinical complications caused by DF. DHF and DSS are reversible vascular complications of DF that cause severe thrombocytopenia and increased vascular permeability [11]. For this reason, a decrease in platelet and white blood cell counts, as well as an increase in plasma leakage, are regarded as highly efficient indicators of dengue infection [12]. Dengue infection symptoms include vomiting, body aches, abdominal pain, and bleeding, in addition to a high temperature [13].

Pakistan is already dealing with the COVID-19 pandemic and another dengue outbreak would be disastrous for the country’s already debilitated healthcare infrastructure. Moreover, since DF and COVID-19 have similar clinical symptoms, they can readily exist as co-infection [14]. For this reason, it is important to have fore-hand preparation of the healthcare system as well as the authorities to avoid further harm and damage.

This study aims to assess the profile of dengue patients presenting to the Emergency Department (ED) of a tertiary care hospital during COVID-19 pandemic. It includes determining their sociodemographic factors including the patients’ residential area to determine dengue endemic regions of Karachi, and the hematological laboratory findings including total platelet count, immunoglobulin M (IgM), immunoglobulin G (IgG), and non-structural protein 1 (NS1) antigens with the associated symptoms of DF.

In this retrospective study, the profile of dengue patients has been assessed whilst COVID-19 was still in effect. In low- and middle-income nations like Pakistan, the co-occurrence of these two infectious diseases might have a significant adverse effect on both the population and the economy [15].

Dengue infections were confirmed through antigen and antibody detection. Several patients tested positive for NS1 antigen but relatively few tested positive for IgG and IgM antibodies. This result shows that the NS1 antigen test was a more potent diagnostic technique for the identification of DF as compared to dengue IgM and IgG antibodies detection.

In contrast to other common symptoms of DF, individuals were more likely to have generalized body ache, abdominal pain, and vomiting. This result was in accordance with a study conducted in Karachi [16].

Additionally, the area of residence of each participant was also included, and it was separated into the districts of Karachi. This was done to determine where the majority of cases originated, which will assist in identifying dengue endemic locations. The results indicated that most of the cases originated in the Korangi district, followed by Karachi East and Malir district. With a population density of 3,900 people per square kilometer (10,000/sq mi), Karachi is an extremely populated city [17]. The two primary causes of the rise of dengue virus infection in tropical emerging nations are an unpredicted rise in population and unplanned urban expansion that leads to major public health problems [18].

This study of patients with dengue showed that the issue of DF has grown even more serious as authorities are busy dealing with COVID-19. Our study concluded that Korangi district was determined to be the most significant dengue-endemic area in Karachi. It is important that the general population, and especially healthcare professionals, should be aware of preventive techniques since doing so will help in the efficient diagnosis that allows appropriate patient care, generation of accurate epidemiological data, and implementation of effective public health actions.

This study shows that there were more female targets than male targets among the affected patients. This is in contrast to many researches where the majority of the patients were male [19, 20]. Social, cultural, and environmental factors may have led to the phenomena of gender specificity in relation to dengue infection. This could be due to society’s neglect towards women’s health problems along with amenia and their debilitating immune system [21].

The district-wise distribution of dengue patients in this study makes it one of its kind to identify the dengue endemic regions of the city. Moreover, this study provides a better picture of dengue cases whilst COVID-19 was at its peak. The limitations of this study include a small sample size and a single-centered design. Furthermore, the patients were not followed up to assess the long-term effects of dengue infection.