INFECTIONS OF SPECIFIC ORGAN SYSTEMS

Infections of specific organ systems Upper respiratory tract infections The common cold The term common cold reflects the feeling of chilliness on exposure to cold that is part of the onset of symptoms. The feeling was originally believed to have a cause-and-effect relationship with the disease, but this is now known to be incorrect. More than 200 years ago, Benjamin Franklin pointed out that colds are caught from other people, not from exposure to a cold environment. The common cold is an acute, communicable viral disease characterized by nasal stuffiness, sneezing, runny nose, throat irritation, and, sometimes, fever. There are more than 100 agents that cause the illness, including parainfluenza, influenza, and respiratory syncytial viruses, as well as reoviruses. Rhinoviruses, however, are the most frequent cause of the common cold. The common cold is an illness that occurs seasonally. Young children can contract between three and eight colds a year, usually coming into contact with the infectious agents in day-care centres or preschools. All available evidence indicates that cold weather, chilled wet feet, and drafts do not cause or increase the susceptibility of people to colds. The usual duration of the illness is about five to seven days, but lingering cough and postnasal discharge may persist for two weeks or more. Diagnosis of a cold is usually made by medical history alone, although it is possible to take a culture for viruses. There is no effective antiviral agent available for the common cold. Therapy consists of treating the symptomsrelieving aches, fever, and nasal obstruction. One of the greatest medical controversies in the 1970s concerned the efficacy of vitamin C in the prevention or treatment of the common cold. In two carefully controlled studies, administration of ascorbic acid (vitamin C) failed to prevent or decrease the symptoms of the common cold. Sinusitis Sinusitis is the inflammation of the mucosal lining of one or more sinuses. It commonly accompanies upper respiratory viral infections and in most cases requires no treatment. Purulent (pus-producing) sinusitis can occur, however, requiring treatment with antibiotics. The origin of sinus infection is much like that of ear infection. Normally the middle ear and the sinuses are sterile, but the adjacent mouth and nose have a varied bacterial flora. Under the usual conditions, very small hairs called cilia move mucus along the lining of the nose and respiratory tract, keeping the sinuses clean. When the ciliary function is damaged, infection can be established. Following a common cold caused by a viral agent, a decrease in ciliary function may permit bacteria to remain on the mucous membrane surfaces within the sinuses and to produce a purulent sinusitis. The organisms usually involved are Haemophilus influenzae, Streptococcus pneumoniae, Staphylococcus aureus, Streptococcus pyogenes, and many other penicillin-sensitive anaerobes. Common symptoms include facial pain, headache, and fever following previous upper respiratory viral illness. On physical examination, persons suffering sinusitis are usually found to have an elevation in body temperature, nasal discharge, and sinus tenderness. The diagnosis can be confirmed by X-rays of the sinuses and cultures of material obtained from within the sinuses. Antibiotic treatment appropriate to the organism that is recovered in cultures is provided for a period of two weeks or longer.