Friday, April 15, 2011

Deteksi dini demam berdarah dengan NS1

        Article Review
         Dr. Yoshua Viventius

             Dengue is a disease that is abundant in tropical countries such as Indonesia. The disease is caused by dengue virus of the genus flavi transmitted by the female Aedes aegypti mosquito. Highest prevalence typically found in stormy times.

             Rule of DBD diagnosis still using the WHO criteria, 1997, that the clinical criteria and laboratoris be less than 100.000/ul thrombocytopenia or increased hematocrit ≥ 20%. To get a big increase in hematocrit ≥ 20% accurate, confidential, given no standard hematocrit value of Indonesian children as well as adults. Besides determining gaining from hematocrit usually only be done in hospital because it takes place treated daily data hematocrit to be able to determine the curve up to the highest and lowest values. According to the authors of DHF diagnosis can only be determined at the hospital on the grounds mentioned above.


            Serological examination IgM and IgG antidengue be required to distinguish between viral fever caused by dengue fever or whether other reasons (typhoid fever, influenza, malaria, hepatitis and others).
There is now a test that can diagnose DHF fever within the first 3 days that is called dengue virus antigen with NS1 antigen. Profit detect NS1 antigen that is to know the availability of dengue infection in patients at the early phase of fever, without having to wait for the formation of antibodies. This must remember traveling very fast when the disease is not addressed quickly. According to the author's experience, NS1 antigen was captured on the first day of fever and after being treated in a hospital and the thrombocyte was going down  compared with patients with negative NS1 result but showing clinical symptoms of DHF.

            Examination of NS1 antigen required to detect the presence of dengue virus infection in the acute phase, in which the various studies show that NS1 sensitivitasnya superior compared to viral culture and PCR screening as well as IgM and IgG antibodies antidengue. NS1 antigen specificity 100% as high as the gold standard of viral culture or PCR.
           Examination of the NS1 antigen rapid screening using a strip or in the form box. This examination has more value compared to other types of inspections such as speed, convenience, high sensitivity results to detect a longer time (from day 1 to day 9 fever), and high specificities (100%)

           NS1 is a highly conserved glycoprotein, which appears to be a significant regio in viral viability but has no biological activity. Unlike other viral glycoprotein, NS1 produced both in relation to the membrane or secreted form (Dussart, 2006).NS1 antigen are good on main and secondary infection. NS1 antigen can be detected in the first 9 days of fever, that there is good in serotypes DEN-1 (highest), DEN-2, DEN-3 and DEN-4 (Alcon, 2002). Kumarasamy, 2007, examined the sensitivity and specificity NS1 in 554 healthy donors and 297 patients infected with dengue virus in which 157 patients with positive and patients examined PCRnya also IgM and IgG antidengue. He get 100% specificity and 91.0% sensitivity of 157 PCR positive samples her with no significant difference for the four serotypes, whereas Blacksell 2008 he examined NS1 and NS1 get 63% sensitivity and 100% specificity to notice a difference in secretion which varied between serotypes.
        There are 2 kinds of NS1 antigen testing kits in Indonesia, namely from Panbio and BioRad, both wearing the principle method of ELISA (Enzyme-linked immunosorbent assay). Currently there are also reagents in the form of NS1 rapid test (ICT).

Conclusion:
Examination by NS1 antigen has a high sensitivity and specificities. But should clinicians should be careful because NS1 antigen negative result does not eliminate the availability of dengue virus infection, unexpected matter relating to the menginfeksi dengue virus serotypes. When found negative results with NS1 antigen screening but clinical signs (+) and therefore should also do an inspection of IgM and IgG antibodies antidengue as a determinant of whether including the type of primary or secondary infection and also to overcome the possibility of false negative results obtained in the examination of NS1 antigen. Do not forget to do regular checks on suspected dengue platelets in patients with symptoms of fever without signs of inflammation.


 References:
1.Application of the Dengue Virus NS1 Antigen Rapid Test for On-Site Detection of Imported Dengue Cases at Airports accessed at:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2668285/
2.The role of dengue NS1 antigen as diagnostic tool
3. Plasma leakage in Dengue Hemorrhagic Fever
http://www.kalbe.co.id/files/cdk/files/06_183Kebocoranplasmadbd.pdf/06_183Kebocoranplasmadbd.html




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