A study of clinical and laboratory profiles of dengue fever in children

Background: Early recognition of characteristic clinical and laboratory parameters of is importantto facilitate prompt diagnosis andtreatmentfor a better outcome, particularly in dengue burden countries. Methods: Children aged less than 15 years who sought medical care in the pediatric department of Saveetha medical college, diagnosed as Probable Dengue/Dengue fever/ dengue with warning sign/severe dengue according to standard guidelines during the study period (July 2017 – December 2017) comprised the study sample. Results: A total of 61 cases were enrolled, of these 36 were boys. The mean age was 6.49 years. Only five patients had severe dengue. Fever (96.7%), loss of appetite (59%), cough and running nose (33%) were common symptoms noted and itching (37.7%) was common during recovery. Only 11.4% of children had bleeding manifestation. Hepatomegaly was noticed in 35 children. Five children went into shock, 2 of whom had hypotension. NS1 was positive in 49%, IgM in 36%, and IgG in 13%. NS1 positivity rate on day 4, day 5 and day 6 of illness were 62.5%, 38.4% and 18.1% respectively. Conclusion: Dengue fever is common during monsoon season, and the course and severity are highly variable. Though the manifestations of dengue are similar to other viral infections, morbidity and mortality are more, thus requiring early diagnosis. As observed in our study the presence of prodromal respiratory symptoms does not preclude the diagnosis of dengue. There should be a high index of suspicion of co-infection, notablymalaria and scrub typhus, if there is an unusual persistence of fever.


Introduction
Day-biting Aedesaegypti and Aedesalbopictus transmitsone of four serotypes of dengue viruses (DEN1-4) of the Flaviviridae family to cause dengue fever. While the primary infection in human has often been in apparent, secondary infection by heterologous types frequently causes severe dengue [1]. Dengue is now endemic in over 100 countries, resulting in 40% of the world's population living mostly in urban and semiurban settings being at risk for dengue.
Although there is no specific treatment for dengue, careful hemodynamic and hematologic parameters monitoring, volume repletion and close observation for the signs of severe disease can reduce dengue' smorbidity and mortality [2]. Dengue virus transmission is ubiquitous with the highest risk in Asia (70%), Africa (16%) and South American countries (14%) of which  [3]. India alone contributes 14% of the global burden which is mainly due to densely populated areas that serve as ideal circumstances for the dengue borne mosquitoes to breed and spread disease [4][5][6].
Dengue is the leading cause of childhood morbidity and mortality globally than any other vector-borne viral disease [7]. In the last few decades, the number of dengue cases has gradually increased in India. Malaria and dengue were the most common causes of fever among hospitalised patients with acute undifferentiated fever [8].
Various factors like change in temperature and precipitation [4], nutritional status of overweight and undernutrition [9,10], inadequate knowledge and preventive measures among the less privileged population about dengue fever attributes to this scenario [11].
Although CYD-TDV vaccine is effective and immunogenic in children, its reduced efficacy against DENV2, which is known for causing severe dengue infection and dengue outbreaks, cause for serious concern. This review aims to address common clinical and laboratory parameters to facilitate early diagnosis of dengue fever, to determine predictors of severe dengue and to initiate appropriate treatment for a better outcome

Material and Methods
Place of study-Department of Pediatric, Saveetha medical college, Chennai

Type of study-Retrospective observational study
Sampling method-Consecutive sampling Inclusion criteria-All patients aged less than 15 years who sought medical care in the pediatric department of Saveetha medical college, diagnosed as Probable Dengue/Dengue fever/ dengue with warning sign/severe dengue according to standard guidelines [14] Exclusion criteria-Children with preexisting haematological illnesses Sample collection-For each patient, basic demographics (name, age, sex, address) was collected. Presenting complaints (duration of fever, myalgia, headache, abdominal pain, vomiting, bleeding manifestations, rash and petechiae) and examination findings (vitals, Hess test, pallor, organomegaly, urine output, signs of fluid retention, circulatory failure)were documented.
Serial laboratory investigations (haemoglobin, total leukocyte count, haematocrit and platelet count) and investigations like Serum glutamic pyruvic transaminase (SGPT), serum glutamic oxalic acid (SGOT) and serum albumin were recorded.
Radiological investigations like ultrasound abdomen and chest X-ray was taken into consideration if available. Details of co-infections/ alternate diagnosis considered at admission/discharge were also recorded.
Statistical method-Statistical analysis was done using SPSS (statistical package for social sciences) software.

Results
A total of 61 cases were enrolled in the months September, October and November, of these 36 were boys and 25 girls. Most of the admissions were in October (61%). There were 14, 37 and 10 admissions in September, October and November respectively. The mean age was 6.49 years; the youngest child isten months old. Of the total cases, the maximum number of admissions was in October (38) which constituted to about 61% of the total patients. Only five patients were diagnosed to have severe dengue. Fever was the most common symptom seen in 96.7% of children among which 40 (65.6%) had an only mild fever. Only 13% had temperature>104° F. The next most common symptom was a loss of appetite present in 36 (59%). Majority of patients did not have any prodromal symptoms; However, 20 (33%) children had cough and runny nose.
Pediatric Review: International Journal of Pediatric Research Available online at: www.pediatricreview.in 232|P a g e    Of the total 61 children enrolled in this study, only five children diagnosed with severe dengue, and 17 had dengue with warning signs. These two categories were combined to form a single severe illness group and compared with the remaining who had either dengue fever or probable dengue (non-severe illness group). Among the critical illness groups, 18 were boys. Nineteen children belonging to the severe illness group stayed in the hospital for more than five days. Flushing and the rashes were significantly more common in the severe illness group. Similarly, anorexia, abdominal pain, edema and itching were more frequent in the critical illness group. However, no significant difference was noted between the two groups in the occurrence of other symptoms (chills, vomiting, loose stool, headache, arthralgia and myalgia).  Among the clinical sign tachycardia (disproportionate to the degree of fever), tachypnea and oliguria were seen only in the severe illness group. The occurrence of bradycardia and hepatomegaly were similar in the two groups. Hyponatremia and low albumin noticed in 5 (22.7%) children who had severe illness. Elevated liver enzyme and leucopenia were distributed similarly in the two group.

Discussion
Boys were more commonly affected in this study group and they also had higher tendency to have severe illness. Similar male preponderance was noted in other studies which may be attributed to the presence of more exposed area leading to more significant chance of mosquito-borne diseases [15,16]. Majority of the children belonged to the 6-12 age group which was also reported in other studies [15,17].
Fever was the most common symptom. Vomiting and anorexia were also commonly seen in our patients. Other widelyrecognisedsymptoms were arthralgia, abdomen pain and headache. This symptom pattern is similar to those reported in several studies [17,18]. Tourniquet test was positive only in few cases. Similar results observed in other Indian studies, probably due to the darker complexion of the study patients here [19,20] However, it was more frequently seen in children with severe illness. Similarly, flushing was also seen more commonly in children with severedisease. These features can be used as an early marker to identify such children. More than a third of the children in our study reported itching during the recovery period. Some of them also had an erythematous rash which was different from the rashes noticed during the initial part of the illness. This rash was not blanchable, more confluent with islets of healthy skin which has been describedas "white islands in a sea of red" [21,22].
One-tenth of the total cases had bleeding manifestations with petechiae being the most common manifestation. A similar result was noticed in the study conducted by Mishraet al [19]. Nearly one-third of children in our study had prodromal symptoms like a cough and runny nose. Other studies did not report these symptoms. The difference could be because this study was conducted during an epidemic of dengue infections, and there was a high index of suspicion among health professionals to screen for dengue. Similar illness presenting with a cough and runny nose during the non-epidemic season would have been regarded as non-specific viral illnesses. More than half of the children [57%] in this study had hepatomegaly similar to previous reviews [23]. However, two children had hepato splenomegaly. Both of them were found to have malariaco-infection.
Thereby suggesting that in our setting whenever there is associated splenomegaly in children with dengue, coinfections with other vector-borne diseases that share similar seasonal trends like malaria and scrub typhus should be considered [24]. Apart from patients with malarial co-infection, two other patient had persistent fever spikes lasting for more than 7 days. These children were found to have gram negative bacterial sepsis complicating their underlying dengue infection, highlighting the need for evaluating children with persistent fever to look for co-infections.
Among the various laboratory parameters, thrombocytopenia was the most frequently noticed abnormality. Majority of them had mild to moderate thrombocytopenia, and a small proportion showed normal platelet counts. Almost three fourth of the children had leucopenia [20,25]. Isolated elevation of SGOT (>120 IU/L) was present in 40% of the children in our study. A similar pattern of transaminitis was described in previous studies, and they observed a positive correlation between the level of SGOT and the severity of illness [26]. Hyponatremia and low albumin noted in children with severe disease, highlighting the importance of these parameters in assessing the risk of severe disease.

Conclusion
Dengue fever is a common cause of acute febrile illness, especially during monsoon season. Though the manifestations of dengue are similar to other viral infections, the disease severity and mortality is more in dengue, thus requiring early diagnosis. As observed in our study the presence of prodromal respiratory symptoms does not preclude the diagnosis of dengue. The course and severity of the illness are highly variable. Apart from the described warning signs, flushing, positive tourniquet test and laboratory derangements like hyponatremia and hypoalbuminemia can be considered as markers of severe illness. The presence of splenomegaly should raise the suspicion of co-infection if there is an unusual persistence of fever considering their common epidemiological background.
Clinical implications of this study-This study highlights the importance of suspecting and evaluating patients for dengue even if they present with prodromal respiratory symptoms and also highlights the need to screen for co-infections if the disease course is atypical.