Hematological Parameters in Dengue fever cases in a tertiarycare center-A Retrospective Study.

Introduction

Dengue is a generally preventable and treatable cause of morbidity and mortalityamong the people that occurs mainly in tropical and subtropical area of the world.1 Dengue fever is caused by one of the four serotypes of the dengue virus (DEN-1, DEN-2, DEN-3 and DEN-4) that belongs to the genus flavivirus of the family of flaviviridae.² The hematological examination is a very important step in the prevention of dengue patients that can observed are change in blood counts, hem concentration due to plasma leakage, leucopenia because of decreased neutrophils near the end of febrile phase, presence of atypical lymphocytes and relative lymphocytosis before shock, thrombocytopenia and change in blood homeostasis with frequent presence of hemorrhagic fever.^1,2 Dengue fever is anarboviraldisease which is caused by the bite of the female Aedesaegypti mosquito.³ Symptomatic dengue fever categories into 3 groups:-undifferentiated fever, dengue fever, and dengue hemorrhagic fever( DHF). DHF was further classified into four severity grades, with grades III and IV being defined as dengue shock syndrome (DSS).⁴ According to average estimates of WHO about 50 million population cases of dengue fever occur annually worldwide and 2.5 billion people live in the risk are of dengue that is why , WHO recently identified among its global research priorities the need for clinical and laboratory indicators for early dengue diagnosis.^1,3,4 Dengue fever is an acute febrile illness characterized by a sudden onset of fever of 3-5 days, intense headache, myalagia, retro-orbital pain, anorexia, gastrointestinal disturbance and rash.⁵ Dengue infection is one of the self limiting disease leading causes of death and hospitalization. It is an epidemic occurred in manila, Philippines in 1953-54, followed by Bangkok in 1958 and Singapore, Malaysia and Vietnam. In India major epidemic illness clinically compatible with dengue was reported from madras in 1780. Later on, spread all over the country.^1-8 The present study was conducted to find out the frequency of dengue positive cases in Karnataka, Bengaluru from January toJuly. The hematological examination can help predict the infection by the specific hematological change.Therefore the present study was conducted to determine the percentage distribution of dengue fever cases in our Hospital and to analyze the various hematological parameters in dengue fever cases.

Materials and Method

A retrospective study was conducted in the central laboratory, department of Pathology from the months of January to July 2019 ina Tertiary Medical College Hospital.With all aseptic and standard precautions Anticoagulated EDTA blood of 2 ml volume was collected and complete blood count analysis was done by using 5 part differential cell counter (Sysmex XN 550) . Internal and external quality controls were performed on a day to day basis and subsequent peripheral smear examination was also done. The haematological parameters analyzed in the study were: leukocyte count, hemoglobin, hematocrit, and platelets count using the same instrument as mentioned above.

Inclusion criteria: All patientsaged more than >18 years (Both from the in- patient and Out- patient departments of Medicine, Obstetrics, Surgery etc.)

Exclusion criteria: All other febrile illnesses other than dengue fever were excluded.

Type of study: Retrospective descriptive study.

Results

A total of 201 patients admitted to the Medical college hospitalwith the maximum number of dengue fever cases noted in the month of July 145(n=72.14%) followed by June 45 (n=22.38%). Males were commonly affected 126 (n=62.68%) than females 75 (n=37.31%).Maximum number of dengue fever cases was seen in the month of July 145 (n=72.14%).

Hemoglobin: Out of 201 cases, 4 (n=2%) cases hadhemoglobinlevelranging between 5-8 g/dl due to severe anemia of dengue fever infection. About 22 (n=10.94%) had hemoglobinin the range of 8-11g/dl and maximum cases 175 (87.06%) were seen with more than 11g/dl.

Hematocrit:There were few cases 14 (6.9%) with hematocrit less than 30% due to dengue infection. Most of the cases 95 (47.3%) were seen with normal hematocrit under the range of 30-40% and 92 (45.8%) had more than 40%

Platelets:Among 201 cases, 10 (4.97%) had less than 20,000 platelets due to severe thrombocytopenia of dengue fever infection, 26 (12.94%) had platelets count 20-50,000 and very few 08 (3.98%) cases were between the range of 50-75,000. Maximum cases 175 (78.11%) were seen with more than 75,000 count. Thrombocytopenia is due to bone marrow suppression and binding of dengue antigen to platelets.

Total count: Among 201 cases, 78 (38.8%) had leucopenia (<4000) due to dengue infection, Maximum cases 112 (55.7%) seen had normal leucocytes count under the range of 4000-11000 and very few cases 11 (5.5%) had leucocytosis which was more than 11000. Leucopeniais due to direct marrow suppression by virus and decreased of neutrophils at the end of febrile phase and reactive lymphocytes.

Discussion

Dengue fever is a self-limiting disease caused by the bite of female aedesaegypti mosquito. Dengue hemorrhagic fever and shock syndrome causes morbidity and mortality. There is no anti-viral treatment and vaccine available hence fluid and electrolyte replacement and supportive therapy are the available modalities of treatment vector control is done by using the mosquito net and ointment.

A total 201 patients, the maximum number of cases were seen in the month of July145 (n=72.14%) followed by June 45 (n=45%) in our study. Out of these 126 (n=62.68%) were males and 75 (n=37.32%) were females. According to the evaluation, there is high number ofexposure of male gender to mosquito bites due to outdoor occupational activities.¹

In our study, dengue was commonest cause of fever with thrombocytopenia in which 4.97% patients had severe thrombocytopenia, 12.94% had moderate thrombocytopenia and 3.98% had mild thrombocytopenia. Maximum cases 78.11% were seen normal platelets count where as studies done by Kate MS, Kumar R and chaudhari A.1 , showed frequent thrombocytopenia and 5.3% had severe thrombocytopenia which is similar to our present study. Thrombocytopenia is due to the direct and antibody mediated destruction of the platelets and megakaryocytes.

In our study, 6.9% had hematocrit<30 due to the dengue fever infection, 47.3% had hematocrit level under the range of 30- 45 and 45% had more than 40% hematocrit level. As similar result were found by Patel K, Patel D, 24.61% had hematocrit<35, 63.85% had 35 to 45 and 11.54% had >45.7 Haem concentration is due to plasma leakage. In our study, 2% had severe anemia, 10.94% had low hemoglobin and maximum cases were 87.06% had hemoglobin level less than 11g/dl. Observation made by Meena KC. showed a 57% had normal hemoglobin level and only 4% had anemia cases.8 This is almost similar to present study.

In our study, Leucopenia was observed in 38.8% of patients. 55.7% had normal leucocytes count and 5.5% had lecocytosis patient s as also similar observed by Patel K, Patel D and Kate MS.^1,7 Leucopenia is due to the direct marrow suppression by the virus.

Dengue fever causes Leucopenia with Lymphocytosis and thrombocytopenia.¹ These causes include bone marrow suppression and binding of dengue antigen to platelets and antibody mediated immunological destruction of platelets.¹ The changes in WBC count are useful in differentiating dengue fever from other febrile illness.¹ Dengue fever is an acute febrile disease characterized by sudden onset of fever of 3 to 5 days, intense headache, myalgia, retro-orbital pain, anorexia, gastrointestinal disturbance and rash.⁵

Conclusion

To conclude dengue fever incidence is increasing day by day. Early detection of severe cases and efficient medical management are of prime importance in endemic areas. Lowered Monocytes, neutrophils count, low hemoglobin and low hematocrit levels are few of the persistent hematological parameters in dengue infection. Peripheral blood parameters are very helpful for diseases monitoring and can be useful in the prediction of the outcome. These parameters if rightly performed and assessed can be of great importance for better patient care in complicated cases.