Dengue fever, a mosquito-borne viral infection, continues to pose a significant global health challenge, especially intropical and subtropical regions. It is caused by four distinct serotypes of the dengue virus (DENV-1, DENV-2, DENV-3, and DENV-4), all of which are transmitted by the Aedes aegypti and Aedes albopictus mosquitoes. Over the past few decades, the incidenceof dengue has increased dramatically worldwide, with many regions experiencing frequent epidemics, particularly in densely populated urban centers where mosquito breeding conditions are favorable (1).The World Health Organization (WHO) classifies dengue as one of the most important mosquito-borne viral diseases affecting humans, with an estimated 50–100 million infections occurring annually prior to 2013 (2). In endemic regions such as South Asia, including India, dengue has emerged as a major public health problem due to increased urbanization, poor sanitation, and ineffective vector control programs (3). The disease presents a wide spectrum of clinical manifestations, ranging from asymptomatic or mild febrile illness to severe dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS), which can be fatal if not managed promptly (4).

One of the unique and challenging features of dengue infection is its unpredictable clinical progression. Primary infection often results in classic dengue fever, characterized by high-grade fever, myalgia, retro-orbital pain, and rash. However, secondary infection with a different serotype is a known risk factor for severe manifestations due to antibody-dependent enhancement (ADE), leading to capillary leakage, hemorrhage,and shock (5). Understanding the clinical spectrum is vital for early recognition and appropriate management of complications, particularly in hospitalized patients who may be at higher risk for severe outcomes.

The diagnosis of dengue is primarily clinical, supported by laboratory investigations such as complete blood count (CBC), liver function tests (LFTs), and confirmatory serological assays including NS1 antigen and IgM/IgG antibody detection. Thrombocytopenia and leukopenia are hallmark features, often aiding in clinical suspicion even before serological confirmation (6). However, there is considerable variability in how patients present, with symptoms often overlapping with other febrile illnesses such as malaria, chikungunya, or typhoid fever. This necessitates a detailed understanding of regional epidemiological and clinical trends to aid diagnosis and treatment.

Hospital-based studies serve a critical role in highlighting not only the clinical profile of dengue patients but also the trends in termsof seasonal variation, age and gender distribution, and complication rates.

These insights are essential for planning public health strategies, especially in resource-limited settings. Numerous studies prior to 2013 have emphasized the need for region-specific data to improve case management and reduce morbidity and mortality. For example, a study by Sharma et al. in North India highlighted that most hospitalizations occurred during post-monsoon months and young adults were the most affected demographic (7). Similarly, a study in Tamil Nadu revealed that gastrointestinal symptoms and bleeding manifestations were more common among children (8).

Despite ongoing vector control and awareness campaigns, dengue continues to burden healthcare systems in endemic countries, emphasizing the importance of hospital-based prospective research to inform clinical practice and public health interventions. Understanding the evolving patterns of clinical presentation over time can assist clinicians in early recognition of severe forms and allocation of healthcare resources during peak transmission periods. This study aims to prospectively assess the clinical manifestations and epidemiological trends of dengue cases admitted in a tertiary care hospital. By analyzing patient demographics, symptomatology, laboratory findings, and outcomes, this research seeks to contribute to the growing body of literature aimed at improving dengue management and forecasting epidemic behavior in similar settings.

This study was designed as a prospective observational investigation conducted at Medical College, in a tertiary care hospital, India.

The research was carried out in the Department of Medicine in collaboration with the Department of Pathology. Institutional Ethics Committee approval was obtained prior to commencement, and informed consent was secured from all participants enrolled in the study.

The study population comprised 150 patients diagnosed with dengue fever presenting with one or more World Health Organization (WHO)-defined warning signs. These patients were either attending the outpatient department or were admitted to the medical wards during the study period, which spanned from March 2012 to December 2012.

Inclusion criteria involved patients who had a confirmed diagnosis of dengue fever with warning signs, as outlined by the WHO guidelines.

Dengue was defined as an acute febrile illness lasting two to seven days, accompanied by at least two of the following clinical features: headache, retro-orbital pain, myalgia, arthralgia, vomiting, skin rash, bleeding manifestations, or leucopenia. Only those cases with laboratory confirmation of dengue infection were included.

Patients with concurrent infections such as malaria or typhoid, or those with pre-existing comorbid conditions, were excluded from the study to eliminate confounding variables. Each participant underwent a thorough clinical assessment, which included a comprehensive medical history and detailed physical examination.

Diagnostic investigations were tailored based on the patient’s presenting symptoms and clinical status, including relevant hematological and biochemical tests performed to confirm diagnosis and monitor disease progression.

Fever (99.5%) was nearly universal, confirming its status as a main symptom of dengue. Myalgia (70.4%), headache (46.4%), and vomiting (43.2%) were also highly prevalent, suggesting the systemic and febrile nature of the disease. Abdominal pain (33.6%) and skin rash (25.6%) were notable, often seen in thefebrile and critical phases of dengue. Petechiae (19.2%), indicative of capillary fragility or early bleeding tendency, reflects the disease's vascular effects. Altered sensorium (10.3%) and hematuria (6.4%) indicate potential progression into complicateddengue, such as neurological or renal involvement. Gastrointestinal bleeding signs like malena (4.8%), hematemesis (4.0%), and epistaxis (4.0%) show that a small but significant number of patients experienced hemorrhagic manifestations.

Table 1: Clinical Presentation of Dengue cases (n=150).

Table 2: distribution of complicated dengue cases among 150 patients

The table illustrates the distribution of complicated dengue cases among 150 patients. The most frequent complication observed was dengue with acute respiratory distress syndrome (ARDS), affecting 38.8% of patients, followed by pleural effusion in 33.3%. Neurological involvement in the form of dengue encephalopathy was noted in 16.6% of cases, while dengue-associated pneumonia was seen in 11.1%. These findings highlight that a significant proportion of dengue patients may develop severe complications, particularly respiratory and neurological, necessitating close monitoring and timely intervention.

This prospective study conducted at a tertiary care center provides crucial insights into the clinical profile and complication patterns of dengue fever in a hospital setting. The findings corroborate the multifaceted clinical presentation of dengue and  derscore the potential for severe complications, which may significantly influence morbidity and management strategies.

Fever was nearly universal in the study population (99.5%), reaffirming its central role in the early clinical diagnosis of dengue fever. This aligns with previous literature, where high-grade fever has consistently been reported as the most common presenting symptom of dengue virus infection, often marking the onset of the acute febrile phase (9). Myalgia (70.4%) and headache (46.4%) were also prominently observed, supporting the understanding of dengue as a systemic illness characterized by widespread inflammation and immune activation (10). These symptoms reflect the cytokine-mediated systemic response induced by viral replication and the host immune system’s reaction to infection.

Gastrointestinal symptoms, including vomiting (43.2%) and abdominal pain (33.6%), were prevalent, highlighting the involvement of visceral organs and plasma leakage in the disease process. Earlier studies have identified abdominal pain as a warning sign for progression to severe dengue and potential complications such as hemorrhage or shock (11). Similarly, skin rash (25.6%) and petechiae (19.2%) reflect the capillary fragility and thrombocytopenia often associated with the critical phase of dengue. These findings are consistent with the vascular permeability and coagulation abnormalities observed in other reports (12).

Of particular clinical concern were symptoms indicative of complicated dengue, such as alteredsensorium (10.3%), hematuria (6.4%), and gastrointestinal bleeding (malena, hematemesis, epistaxis in 4.0–4.8% of cases). Neurological manifestations such as altered sensorium may result from hepatic encephalopathy, dengue encephalitis, or profound hypotension and cerebral hypoperfusion (13). Hemorrhagic symptoms, though less frequent in this cohort, are consistent with dengue hemorrhagic fever (DHF) and signal a need for prompt and aggressive supportive care.

A striking aspect of the present study was the high incidence of severe complications. Acute respiratory distress syndrome (ARDS) was observed in 38.8% of patients, while pleural effusion occurred in 33.3%. These complications are typically associated with the plasma leakage syndrome described in the critical phase of dengue and may lead to hypoxia and respiratory failure if not identified early (14). Previous studies have emphasized that ARDS, though less frequently reported, is a life-threatening manifestation requiring ventilatory support and intensive monitoring (15).

Neurological complications, including dengue encephalopathy (16.6%), further reflect the disease’s neurotropic potential, although such complications are under-recognized in clinical settings. These findings support earlier observations that neurological manifestations may arise due to cerebral edema, hemorrhage, or immune-mediated mechanisms (16). A smaller proportion (11.1%) developed dengue-associated pneumonia, potentially due to secondary bacterial infections, compromised immunity,or prolonged hospitalization—factors well-documented in prior research (17).

The incidence of multiple severe complications observed in this cohort underscores the need for vigilant monitoring, particularly during the defervescence period when many complications are likely to arise. The WHO has emphasized the importance of recognizing warning signs during this period to anticipate potential deterioration and guide hospitalization decisions (2).The pattern of clinical features and complications in our cohort closely mirrors earlier findings from Indian subcontinent studies. For instance, Balasubramanian et al. reported similar rates of gastrointestinal and bleeding symptoms in hospitalized pediatric dengue cases, with a strong seasonal and post-monsoon predilection (8). Meanwhile, Sharma et al. documented a higher frequency of respiratory and systemic complications in adult dengue cases during epidemic periods, paralleling our findings on ARDS and pleural effusion prevalence (7).Given that dengue remains hyperendemic in many regions, with periodic epidemics driven by serotype shifts, vector proliferation, and climatic factors, the burden on healthcare infrastructure can be substantial. Our findings highlight the necessity of early diagnosis, stratification of risk, and timely referral to higher centers for complications such as ARDS and encephalopathy. Moreover, integration of clinical vigilance with laboratory parameters—especially monitoring hematocrit, platelet count, and liver function—remains pivotal in reducing dengue-related mortality.

While this study provides valuable insights, it is limited by its single-center design and relatively small sample size, which may affect generalizability. Additionally, serotyping of dengue virus was not performed, whichcould have provided further context, as different serotypes and secondary infections have been linked to more severe outcomes (5). Future multicenter studies with serotype analysis and long-term follow-up may help clarify predictors of severe dengue and guide vaccine and vector control policies.

The findings underscore the importance of early recognition of both typical and atypical symptoms to facilitate timely diagnosis and intervention. The high incidence of respiratory and neurological complications observed in this cohort calls for heightened clinical vigilance, particularly during the critical phase of illness. Effective monitoring and supportive care remain central to reducing the risk of fatal outcomes in severe dengue.Additionally, these results reaffirm the value of hospital-based surveillance in identifying trends and improving the management of dengue cases, especially in endemic and epidemic-prone regions. Proactive public health strategies, including community awareness, timely vector control measures, and clinician preparedness, are essential to mitigate the burden of dengue-related complications.

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