Clinical Problems

Viruses are among the most important causes of morbidity and mortalities both in children and elderly patients. They cause variety of illnesses. Most of these illnesses are caused either by the immune responses or by direct cytopathic effects. For example, the clinical problems experienced by patient infected with influenza A virus is to most part due to chemical substances produced by white blood cells. These chemicals are commonly known as Interleukin or Cytokines. They have effects not only on organs, tissues and cells of the immune system but also on others as well. Due to their effects, a patient infected with an influenza virus would present with fever, joint pain, headache and general weakness. On the contrary, some viruses have direct cytopathic effect. Herpes simplex virus is known to be a highly cytopathic virus and it can cause tissue necrosis in brain and other vital organ of neonate if treatment is not started promptly. The fatality rate in this group of patients could be as high as 80-100 %.

 There are other viruses that target the immune system and HIV is one of the examples. HIV mainly infects the T helper cells which play a central role in cell and antibody mediated immunity. Patient with small number of T helper cells are prone to opportunistic infections and malignancies. The other groups that should be mentioned here are viruses that are associated with malignancies. These viruses can induce neoplastic changes. For instance, hepatitis B Virus and Papillomavirus are known to be important causes of hepatocellular carcinoma and cervical cancer respectively.

Most viruses are known to cause asymptomatic infection. On the other hand, others are known to causes illness in all infected patients (e.g. HIV) even if patients may not present with clinical problems for months to years.

Symptomatic patients may present with one or more of the problems listed below.

• Eye problems (Conjunctivitis and retinitis)

• Respiratory diseases (Common cold, Pharyngitis, Croup, Bronchiolitis, Pneumonitis)

• Cardiovascular (myocarditis)

• Jaundice/hepatitis

• Meningitis & Encephalitis

• Gastroenteritis/diarrhoea

• Joint pain

• Skin rashes (vesicular lesion, Maculopapular lesion)

• Infections in pregnancy

You are advised to look other sections for investigations and managements of specific viral infections.