Diagnosing h1n1 virus

In addition to rapid tests, there are several more accurate and sensitive flu tests available that must be performed in specialized laboratories, such as those found in hospitals or state public health laboratories. All of these tests are performed by a health care provider using a swab to swipe the inside of your nose or the back of your throat. These tests do not require a blood sample. For more information, see Seasonal Influenza Testing.

Rapid tests vary in their ability to detect flu viruses. This means that some people with a H1N1 flu infection have had a negative rapid test result. This situation is called a false negative test result. Rapid tests appear to be better at detecting flu in children than adults.

Not necessarily. Your health care provider may diagnose you with flu based on your symptoms and their clinical judgment or they may choose to use an influenza diagnostic test. Depending on their clinical judgment and your symptoms, your healthcare provider will decide whether testing is needed and what type of test to perform. Most importantly, PCR technique has been found to yield high sensitivity and specificity in adults who have low titre of viruses than children.

Every patient and clinician wish to know the causation of disease as early as possible after the illness begins. To meet this aim, rapid tests to detect influenza virus have evolved. In the past decade, several tests have been developed and the use of rapid tests is found to flourish day in day out. This is true because of their ability to provide test results within about half an hour with easy interpretability. Although these tests have not been able to gain trustworthiness because of several limitations like frequent false positivity and false negativity, they are known to yield better results with sample having higher titer, as in children than in adult cases.

These tests are handy and also known as near patient or point of care testing methods. Today's focus on rapid identification of influenza should be centered to increase the sensitivity and specificity of these tests, so that they can be of potential use in early and accurate diagnosis of influenza.

The commercially available rapid antigen tests are mostly immunoassays that target the antigen of influenza virus. However, they have relatively poor sensitivity in comparison to virus culture technique and PCR-based assays. Nevertheless, they found the sensitivity of Formosa Rapid test to be similar to QuickVue test, relatively more sensitive than the other 2 kits for H1N1 09 diagnosis.

The next important thing about the rapid kits is that their sensitivity and specificity are inconsistent. Several studies have been performed, especially surveillance ones, solely based on the DFA test. The time frame to obtain the results is between 2 and 4 h.

Similarly, specificity ranges from This means that the negative results need to be confirmed by the PCR-based assays.

The performance of the test was better with children below 10 years of age, whereas the sensitivity of the test decreased with persons above 30 years of age.

In another study, the sensitivity of DFA is shown to be lowered to However, the DFA test requires skilled expertise for fluorescence microscopy. Furthermore, the DFA test is carried out in shift basis generally in the clinical settings, which prolongs the turnaround time.

Thus, it does not seem to be a suitable test in regard to clinical laboratory diagnosis of influenza virus in comparison to PCR based assays. Number of studies have reported that PCR-based assays overcome several demerits possessed by other techniques such as rapid influenza detection tests RIDTs and SVC with respect to sensitivity, specificity and time frame.

Briefly, RNA extracted from the influenza sample is purified and transcribed using the oligonucleotides specific to the target sequence, producing cDNA.

For instance, PCR-enzyme immunoassay has been found to have better performance than the culture method in cases with days of illness. These multiplex RT-PCR techniques are highly sensitive and specific to give result in comparatively less time than the viral culture and EIA techniques. However, intensive research in medical diagnosis has led even more effective diagnostic tools, based on PCR assays.

For instance, nucleic acid sequence-based amplification tests are known to be more sensitive than the RT-PCR tests for the detection of influenza virus. It can detect the H1N1 09 in 90 min with sensitivity and specificity of Although nucleic acid-based amplification assays are found to yield better sensitivity in comparison to other methods, more other techniques are being studied by FDA. The knowledge on the genetic basis of resistance to drugs has provided molecular techniques to quickly detect the mutations conferring resistance to the drugs.

For instance, one of the most widely used drugs against influenza infection, oseltamivir resistance, arises due to histidine to tyrosine substitution in the neuraminidase active site HY. Sequencing methods such as pyrosequencing provide detailed genetic information about the resistance pattern and also estimate relative proportion of variant and wild-type viruses in a mixed population sample and can be applied directly in clinical setting. Influenza virus is a significant global health burden.

Timely diagnosis and initiation of treatment reduce the stigma of the disease, and also helps in outbreak control. Sole interpretation by a clinician, based on the symptoms presented by a patient, is not specific, as the virus has symptoms common to other known respiratory viruses. Therefore, clinicians are always in need of a confirmatory test for the influenza infection as soon as the illness initiates.

The culture methods are time-consuming and are not as sensitive and specific as to make clinicians to start with antiviral therapy. However, they are still being used in many laboratories, suggesting that the influenza diagnosis by culture methods needs substantial quality check and continuous monitoring to increase the quality of report.

The fast and specific RIDTs, also called as point of care tests, are also not appropriate for the diagnosis of influenza virus because of their poor performance. However, they are simple, cheap, easily interpretable and handy. If they had been showing similar or better performance than that of PCR-based assays, they would have been the major technique to detect the influenza virus.

However, they too need to be studied well and improved to the extent where they can be used for accurate and specific diagnosis of the virus. Recent advancement in the PCR-based assays have become popular in advanced countries. However, we cannot deny the fact that these popular models also have several limitations, ranging from nucleic acid extraction to result interpretation. Even a negligible amount of error has potential effect on the result interpretation of the highly sensitive tests.

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Lyme Disease. Antibiotic Treatment. Chronic Lyme Disease. Featured Research. Types of PIDDs. Talking to Your Doctor. Therapeutic Approaches. Though aspirin is approved for use in children older than age 3, children and teenagers recovering from chickenpox or flu-like symptoms should never take aspirin. This is because aspirin has been linked to Reye's syndrome, a rare but potentially life-threatening condition, in such children. If you have the flu, you can give it to others.

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This content does not have an Arabic version. Diagnosis Your doctor will conduct a physical exam, look for signs and symptoms of influenza, including H1N1 flu swine flu , and possibly order a test that detects influenza viruses such as H1N1.

Request an Appointment at Mayo Clinic. Share on: Facebook Twitter. Show references Key facts about human infections with variant viruses. Centers for Disease Control and Prevention. Accessed Jan. Dolin R. Epidemiology of influenza. Grohskopf LA, et al.