The virus-drug-host dynamics in the tomographic charaterization of pulmonary influenza A (H1N1) infection – a clinical-radiological-pathological view

Abstract

Common cold and flu refer to different clinical entities. Common cold is a benign and self-limited syndrome comprising a group of diseases caused by different virus families (1). Approximately 200 virus subtypes are associated with common cold. Rhinovirus, with more than 100 serotypes, is collectively the most common virus (30% to 50% of the cases), while coronavirus accounts for 10% to 15% of the cases. The symptoms predominate in the upper airways and there is little systemic repercussion. Complications or death are not common (1). Flu, or seasonal influenza, is caused by the influenza A and B viruses, and predominates in the winter in the form of outbreaks or epidemics. It manifests with signs and symptoms in the upper and lower airways and remarkable systemic involvement. The noncomplicated condition, although followed by acute and debilitating symptoms, is usually self-limited. For susceptible individuals, the seasonal influenza brings greater risk for morbidity and mortality (complicated presentation). The incubation period ranges from 1 to 4 days (2). Seasonal influenza is responsible for 200,000 hospital admissions and 41,000 deaths per year in the United States of America (seventh cause of deaths) (3). The seasonal influenza viruses are included in the Orthomyxoviridae family and are classified into A, B, or C. The influenza A virus can be found in humans, other mammals, and in birds, and, among them, is the only historically responsible for pandemics. The B and C types, although previously identified only in humans, were also isolated in seals and pigs, respectively. Influenza A and B viruses are more relevant than influenza C virus for human beings and cause more severe infections. The latter may cause respiratory infections in children with less than 6 years of age. Usually, the exposure to influenza C virus during the childhood usually causes protection against new infections in adulthood (2) .