Muhammad Kashif Munir, Rizwan Iqbal, Arslan Ahmed Salam, Sana Rehman, Tahir Khalil, Muhammad Aasim.
Frequency of confirmed dengue fever cases among patients presenting with fever to a tertiary care hospital and a private laboratory.
Pak J Med Res Jan ;54(2):51-6.

Background: Dengue fever is a viral disease transmitted by infected female Aedes aegypti mosquitoes. The infection is becoming endemic and complicating in Pakistan after the massive 2011outbreak that caused considerable morbidity and mortality. Objectives: To calculate the frequency of confirmed dengue infection in patients presenting with fever to tertiary care hospital and private laboratory. Study settings and duration: Pakistan Medical Research Council, TB Research Centre in collaboration with Emergency Laboratory Mayo Hospital Lahore and a private laboratory (Saadan Hospital Lahore) from June, 2012 to February, 2013. Patients and Methods: After taking informed consent from departmental heads and from patients, all patients presenting with high grade fever, headache, vomiting and abdominal pain and having provisional diagnosis of dengue fever were registered and underwent complete blood count (CBC). All those who had a platelet count of less than 150 thousand/µl in their first report were further tested for dengue IgM and IgG. All patients were followed for 7 days and CBC reports were collected. A semi-structured questionnaire containing the information about names address, phone number, sign & symptoms, CBC, dengue IgM and IgG was collected from the record of the patient or the reports of the patients and entered on data sheet. Interpretation of tests was presence of both IgM and IgG in one patient indicated past and present exposure both (secondary infection). Isolated presence of IgM indicated 1st acute infection and isolated IgG indicated previous exposure to dengue. Results: A total of 647 patients were initially recruited, out of whom, 164 (25.4%) had platelet count of less than 150 thousand/µl and these patients were further tested for dengue IgM and IgG. Dengue IgM, IgG or both were found in 131 (79.9%) cases of which 46.6% were positive for both IgM and IgG antibodies while, 35.1% were positive for IgM and 24 (18.3%) for IgG antibodies. All these patients were followed for 7 days. Out of 131 patients, 61 (46.6%) were positive for both IgM and IgG antibodies, indicating a secondary infection. Isolated dengue IgM was positive in 46 (35.1%) patients indicating acute infection while 24 (18.3%) had only IgG positive indicating past exposure. Overall acute dengue infection was seen in 81% cases. Mean platelet count in isolated dengue IgM or IgG positive patients was 47,000 and 48,500 respectively, on day one but these values were further low i.e. 45,500 in those who were both IgM and IgG positive (secondary infection). Improvement in platelet counts was observed from day 4 onward, with slower rise in those having secondary infection as compared to others. Conclusion: Almost 81% patients had acute dengue infection out of which 46.6% had secondary infection. Almost 18% patients had past exposure to dengue infection.

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