The effect of weather on some infectious diseases

For several years the Royal College of General Practitioners has been collecting data supplied by local doctors throughout Britain on some infectious diseases seen in their practices. We describe a method of computerisation of this information and statistical analyses. We are investigating the influence of external factors such as climate on the infectiousness of some diseases. A model is fitted involving a non homogeneous two-state Markov chain whose transition probabilities are governed by the explanatory data.