Disease Transmission and Mans Resistance 299 



animal materials to be consumed as food. Lack of proper sanita- 

 tion and improper refrigeration are the principal causes of food 

 poisoning. 



DROPLET INFECTION 

 Any person suffering from an upper respiratory infection is a 

 potential hazard to others with whom he may come in contact. 

 Whether this disease is spread to others depends upon the virulence 

 of the organism, the susceptibility of the contact, the time factor 

 after the droplets were expelled, the number of organisms involved, 

 and a host of other inter-dependent forces. 



DIRECT CONTACT 

 If pathogens are transferred directly from one individual to an- 

 other through direct contact of kissing, etc., little opportunity is 

 afforded for the organism to be weakened by drying, exposure to 

 sunlight, and other factors. If the new host provides favorable 

 conditions for the multiplication of the bacteria, another link in 

 the chain reaction has been provided, and the disease continues to 

 spread. 



TYPES OF DISEASE 



CHRONIC DISEASE 

 When a disease progresses slowly and lasts for extended periods 

 of time, it is called a chronic disease. Rheumatism, arthritis, 

 leprosy, and some forms of tuberculosis fall into this category. 



ACUTE DISEASE 

 If a disease reaches a point of greatest intensity in a relatively 

 short space of time and recovery is not prolonged for months or 

 years, we term it an acute disease. Pneumonia, typhoid fever, 

 and diphtheria are examples of acute diseases. There is no sharp 

 dividing line, however, between acute and chronic illnesses. 



ENDEMIC DISEASE 

 An endemic disease (en, in: demos, people) is one which is 

 usually present in small numbers in any given community. Some- 



