Viral Diseases

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Viral Diseases:

Some viral illnesses present with typical symptom like -measlesMeasles Mumps Causative Virus Diagnosis Clinical Signs and Symptoms With Treatment. Read more ... », mumps, and chickenpoxRUBELLA and CHICKENPOX SMALLPOX Diagnosis Clinical Signs and Symptoms With Treatment. Read more ... ». In many others, the clinicalMitral Regurgitation (MR)Causes Symptoms Mitral Regurgitation Treatment of Mitral Regurgitation ACC/AHA guideline. Read more ... » picture suggests any of a number of viruses.
For example, aseptic meningitis can be caused by the mumps virus, lymphocytic €€choriomeningitis virus, and several other enteroviruses, among others. SymptomsMitral Regurgitation (MR)Causes Symptoms Mitral Regurgitation Treatment of Mitral Regurgitation ACC/AHA guideline. Read more ... » of respiratory disease with many viruses are indistinguishable.
Some viral diseases have a characteristic type of rash, although in most cases the rash associated with viral syndromes is not pathognomonic.

Identify a virus is useful for confirmation of atypical cases, help with outbreak tests investigation, elucidation of confusing syndromes, and increasingly to support need for specific antiviral therapy.
The frequency with the certain pathogens cause certain type of diseases allows for educated guesses, eg, respiratory type of syncytial virus (RSV) for bronchiolitis or parainfluenza virus for croup. Instances in which rapid diagnosisMitral Regurgitation (MR)Causes Symptoms Mitral Regurgitation Treatment of Mitral Regurgitation ACC/AHA guideline. Read more ... » assists in patient managementChronic Renal Failure (CRF) Risk factors Causes Stage CRF Treatment. Read more ... » are noted.

Several techniques are used for diagnosis, including stain in , cell culture €coxsackievirus in suckling mice., immunologic detection €seroconversion with arbovirusesDengue fever Dengue haemorrhagic fever Diagnosis Signs and symptoms Treatment. Read more ... », rabiesRabies Hydrophobia Clinical Findings Diagnosis Signs and symptoms with treatment. Read more ... » virus on skin biopsy, detection of secretory€ immunoglobulin A [
IgA]), or molecular techniques such as polymerase chain reaction (PCR) (for herpes simplexViruses General Introduction To VIRAL DISEASES Diagnosis Treatment with Causative Agents. Read more ... » virus [HSV]) or antigen assays (for cytomegalovirusViruses General Introduction To VIRAL DISEASES Diagnosis Treatment with Causative Agents. Read more ... » [CMV]).
Isolation of virus from a normally sterile site (cerebrospinal fluid, lung) or from a lesion (vesicles) in an immunocompetent individual is diagnostically significant. Isolation from nonsterile sites (nasopharynx, stool) may represent a carrier state, and seroconversion and pathologic change are needed to establish a diagnosis.

Microscopic techniques are used to examine cells, body fluids, or biopsy material in search of virus or cytopathic changes specific for one virus or a group of viruses (eg, multinucleated giant cells at the base of herpes lesions, rotavirus structures on electron micrographs of diarrheal stools).
Immunofluorescent methods, often with monoclonal antibodies, can rapidly identify some antigens (rabies, varicella, herpes simplex, RSV) in desquamated or scraped cells.

Specific antibodies to viruses rise during the course of illness, though the rise and persistence of titer depend on both the virus and the host response. A fourfold or greater rise in antibody titer during illness is considered evidence of disease.
Single determinations are seldom helpful, and laboratories require paired sera (acuteMitral Regurgitation (MR)Causes Symptoms Mitral Regurgitation Treatment of Mitral Regurgitation ACC/AHA guideline. Read more ... » and convalescent, typically 2–3 weeks apart). Antigenic detection is used for certain viruses (hepatitis BHepatitis Types Causes Symptoms Diagnosis and Treatment. Read more ... » surface antigen [HBsAg], CMV, HIV), with viral presence detected independently of disease duration or host response.
As more is learned of the natural history of HSV-1 and HSV-2 infections, these viruses are increasingly managed clinically with support from serologic data.
Quantification of viral antigen titer is useful in the management of HIV disease and is becoming a standard of care for other chronicChronic Hepatitis Classification viral hepatitis Clinical features and Treatment. Read more ... » viral infections (eg, hepatitis B and C virus [HBV, HCV]).

Molecular €€Techniques

Molecular technology has provided €€techniques such as PCR and nucleic acid probes that have proved useful in the identification of new pathogens €€
€€, HCV and Kaposi’s sarcoma herpesvirus€€) as well as for the management of patients in whom quantification of viral activity, €€as with immunologic techniques, assists in following the course of clinical illness or the response to therapy. Results vary among laboratories.

The €€armamentarium of antiviral therapy has expanded greatly with the advent of the HIV outbreak , though for many viruses there remains no definitive antiviral therapy.
The mainstay of controlling viral diseases is vaccination. Currently available live vaccines include those against measles, mumps, rubellaRUBELLA and CHICKENPOX SMALLPOX Diagnosis Clinical Signs and Symptoms With Treatment. Read more ... », €poliovirus (€€Sabin vaccine)€€, yellow fever, and varicella.
The inactivated vaccines protect against the agents implicated in poliovirus (Salk vaccine), hepatitis A, hepatitis B, influenzaInfluenza SARS and Whooping Cough Signs and Symptoms with Diagnosis and Treatment. Read more ... » A and B, rabies, €respiratory syncytial virus (€€RSV), and Japanese B encephalitis. €€Passive immunoprophylaxis remains important in prevention of hepatitis A and B,€€ RSV infection and, among the immunosuppressed, varicella. €€
There is now a trend favoring the combination of vaccines, with the sacrifice in immunogenicity compensated for by the increased €€compliance with vaccinations by the vaccinated patient and their families.