JOURNfll OF MILITflRV PHRRMRCO-MCDICINC N°7-2014
FEATURES OF CLINICAL AND LABORATORY OF THE DENGUE VIRUS AMONG INFECTED ADULTS IN HANOI 2013
Nguyen Trong Vien*; Van Dinh Hoa**; Hoang Vu Hung***; Vu Xuan Nghia*
SUMMARY
fiJI patients (60) clinically suspected to have dengue infection were tested. Among them, 22 patients had fever ranging from 38.2 - 40.1°C (mean temperature 39.2°C). Most patients were admitted on the 3"^- 4' day of illness (range 1 - 7 days). The most prominent clinical manifestations included myalgia, anorexia, rashes, abdominal pain, flushed skin and abdominal tenderness. Laboratory results showed that 24 samples (40%) were positive for dengue specific antibodies using IgM/IgG capture ELISA. 8 samples (13.33%) were positive for the dengue virus specific nucleic acid. All four dengue serotypes were tested, among which dengue virus 1 (37.5%) and 2 (62.5%) were the two common serotypes.
• Key word: Dengue; Features of clinical and laboratory; Adults; ELISA, RT-PCR INTRODUCTION
Dengue is considered the most important arbovlral disease affecting humans. It is also named a mosquito-borne disease caused by one of the four serotypes of dengue viruses (DEN 1 to 4). Dengue infection has increased worldwide and an estimated 50 -100 million cases of dengue infections are reported annually from more than 100 tropical and subtropical countries of the world. The clinical presentation of dengue virus infections, which ranges from a mild unspecific febrile illness to dengue haemonrhagic fever (DHF) and dengue shock syndrome (DSS) is various.
In order to diagnose clinical dengue infection, almost cases depended on the WHO criteria. Because of the variability of the clinical presentations associated vuiUi dengue infection, laboratory confirmation is required.
Serologic tests are more commonly used to confirm the presence of antibodies to dengue virus. These serologic tests have similar sensitivity (> 90%) and specificity
(> 90%) rates. The gold standard for dengue diagnosis is virus isolation from clinical samples. The \flral RNA genome are detected through viral culture and RT-PCR.
This study aims to determine the serotype of dengue virus by viral RNA genome isolation using RT-PCR or detection of dengue-specific antibodies using IgM/IgG capture ELISA.
METERiALS AND METHOD The cohort study was conducted at 103 Hospital and Dongda Hospital, Hanoi, from May to August, 2013. All patients above 18 years old admitted and suspected to have dengue infection based on the WHO criteria were included.
Serum specimens for virologic (RT-PCR) and serologic studies (dengue IgM/IgG capture ELISA) were obtained on admission. All specimens were sent to the Virology Medical Laboratory at the Biological Medical Researched and Applied Center (VMMU) for analysis.
* Vietnam Military Medical University
" Hanoi Medical University
**-103 Hospital
Corresponding author: Vu Xuan Nghia ([email protected])
JOURNAL OF marrSSV PHBRMBCO-meDIClNC N ° 7 - M 1 4 To determine the serotype causing the dengue infection, virus isolation and nucleic acid amplication was done using the acute phase sera. Dengue virus RNA was extracted using QIA amp viral RNA mini kit and was amplied by reverse transcriptase-PCR method (Invitrogen one-step RT-PCR virith Superscript III and Platinum Taq). The target region was dengue virus C-pre M region, subtype- specific internal conserved region. A dengue group-specific and serotype specific
primers to demonstrate the presence of virus-specific RNA was used.
A confirmed case of dengue virus infection based on a clinical and laboratory presentation of dengue-like illness with dengue virus-specie antibody (IgM/IgG) from sera using dengue IgM/IgG capture ELISA; or detection of the viral genomic sequence in the seaim samples by RT-PCR,
Data analysis: data was done using SPSS v16 software.
RESULTS AND DISCUSSION 1. Determining the dengue infection patients.
Results in table 1 present for all patients who were clinically suspected to have dengue infection. 24 samples (40%) were positive for dengue specific antibodies using IgM/IgG capture ELISA. 8 samples (13,33%) were positive for the dengue virus specific nucleic acid. All four dengue serotypes were tested, among which dengue virus 1 (37.5%) and 2 (62.5%) were the two common serotypes. Dengue vinis infection was confirmed in 40% of cases using Igiy/IgG capture ELISA and 13.33% using dengue serotyping by RT-PCR. 28 of the 60 cases had negative results in 2 confirmatory tests done.
Table 1: Determining test for dengue virus infection.
DENGUE VIRUS
Positive Negative
ELISA {IgM/IgG) (n = IgM
(n « 60) 12 48
IgM/IgG (n = 60) 8 52
60) IgG (n = 60)
4 56
RT-PCR (n = 36) Serotype 1
(n = 36) 3 69
Serotype II (n-36)
5 65
The diagnosis of dengue infection mostly used serological tests. Recently, a few studies have used viral culture for detection and detection of viral serotype.
Although all four serotypes of dengue viruses were tested from our patients, DEN1 and DEN2 were detected, but DEN2 was the predominant serotype. For serotype examination, RT-PCR was used and it is one of the most specific tests to confirm dengue infection. The positive
results of the RT-PCR will be done when the sample Is collected in early phase, which occurs within the first to fifth day of the onset of symptoms. In our research, only 36 samples were detected by RT- PCR and only 8 samples were positive.
This may be tjecause some of the patients were in the late viremic or post-viremic phase already. Another reason for the low rate of RT-PCR positivity may be due to failure to maintain the cold chain during 90
JOURNAL OF MILITRRV PHRRMRCO-KUDICINC N°7-2014
transport of the samples, resulting in vlnjs Inactivaflon. 28 patients with clinically suspected infection but negative results in all the confirmatory tests could have other viral infections, which should be Chikungunya virus.
2. Characteristics and clinical manifestations of patients with dengue infection.
TaWe 2: Characteristics of patients with dengue infection.
CRITERIA
Year
Signs and 1 8 - 3 0
31 - 6 0 Anorexia
Myalgia Nasal congestion
Cough Headache Abdominal pain
Flushed skin Abdominal tenderness Hepatomegaly Maculopapular rashes Fever
MALES (n = 10)
8
2 7
4 9
3 10 5 2 2
2 8
10 FEMALES
(n = 22)
15
7 13
12 16
9 21 12 5 1
3 2
22 TOTAL
(%)
(n = 32) 23
9 20
17 25
12 31 17 7 3
5 10
32
Table 2 presented the clinical manifestatbns of the patients with dengue infection.
There were totally 32 patients and majority was less than 30 years. Most patients in our population were females and it was reported that DHF was more severe among females, although there was no evidence that dengue virus is a gender- specific disease. However, this finding was
not seen in our study. All patients had fever ranging from 38.2 - 4 0 . r c (mean 39.2'=C) and were admitted on the 3"^ - 4'"
day of illness (range 1 - 7 days). The most prominent clinical manifestations included myalgia, anorexia, rashes, abdominal pain, flushed skin, and abdominal tenderness.
Compared to previous studies, the signs and symptoms in our research were not so specific (myalgia, anorexia, abdominal pain, cough and headache). The most common symptoms in this study were skin manifestations (maculopaputar rashes and flushed skin) and abdominal tenderness, similar to the previous researches. The signs of rash and skin flushing in patients with dengue infection may be due to the perivascular edema caused by infiltration of the microvasculature of the dermal papillae with lymphocytes and monocytes.
However, hepatomegaly was seen in only a small number of our patients.
7a6/e 3: Laboratory of patients suspected to have dengue infection.
LABORATORY PARAMETERS Lowest platelet count (x 10''^/L) Highest tiematocrit (%) LoweslWBC(x10^/L) SGPT (U/L) Albumin (g/L)
MEANS (SD) 8 8 . 1 (27.3) 4 4 . 9 (5.6) 3 . 9 0 ( 1 . 1 7 ) 8 2 (48.5) 3 3 , 4 (3.5)
From table 3, results show that thrombocytopenia and leukopenia were found in our patients. One patient with confirmed dengue infection presented had WBC count of 7 X 10'/L. Contrary to common observation that patients with dengue infection often present with 91
JOURNAL OF MILITflRV PHRRMflCO-MCDICINe N°7-2014
leukopenia, WBC counts in DHF are variable, ranging from leukopenia to mild leukocytosis. Relative lymphocytosis was seen in our results, which is manifested in another study in which lymphocytosis was observed in DHF patients Relative lymphocytosis is a common finding In dengue-infected patients before detevescence and the onset of shock. Other laboratory parameters showed hypoalbuminemia, which is a manifestation of loss of albumin from plasma leakage, and is probably a detenninant of the severity of disease In DHF. However, in our population, those that presented with pleural effusion showed normal albumin levels. This means that hypoalbuminemia in patients with dengue may also be due to other factors like poor nutrition and mild metabolic dysfunction. Liver transaminases were elevated, especifically SGPT. The underlying pathology is focal necrosis of hepatic cells during the acute phase infection, which rapidly improves as the fever subsides.
CONCLUSION
In the dengue outbreak in 2013, all patients (60) suspected to have dengue infection according to WHO standard were tested.
We found that 32 samples (53.33%) were confirmed to be Infected with dengue infection by serologic and virologic examinations.
The remaining 28 patients with negative results on all the confirmatory tests could have other viral infections, which should be Chikungunya virus.
REFERENCES
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3. Gubler DJ. Serologic diagnosis of dengue/
dengue hemorrhagic fever. Dengue Bulletin 1996,20, pp.20-23.
4. Vaughn DW, et at Dengue viremia titer, antibody response pattern and virus serotype correlate with disease severity. J Infect Dis.
2000, 181,pp.2-9.
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