Epidemiology Incidence peaks in the winter, taking the form of local epidemics lasting a few weeks or months. The same serotype may return to an area after several years. Diagnosis Colds caused by coronaviruses cannot be distinguished clinically from other colds in any one individual. Laboratory diagnosis may be made on the basis of antibody titers in paired sera. The virus is difficult to isolate.
Hygiene measures reduce the rate of transmission.
There is no evidence, however, that human coronaviruses can be transmitted by animals. In animals, various coronaviruses invade many different tissues and cause a variety of diseases, but in humans they are only proved to cause mild upper respiratory infections, i.e. common colds. On rare occasions, gastrointestinal coronavirus infection has been associated with outbreaks of diarrhoea in children, but these enteric viruses are not well characterized and are not discussed in this chapter. Clinical Manifestations Coronaviruses invade the respiratory tract via the nose. The disease resolves in a few days, during which virus is shed in nasal secretions.