a. Respiratory Diseases. These are usually transmitted from person to person
by discharges (spray, cough, sneeze, breath) from the nose, mouth, throat, or lungs of
an infected individual. Examples: common cold, pneumonia, sore throat, and
b. Intestinal Diseases. Usually transmitted by food and water that has become
contaminated with feces or urine from an infected human or animal. Examples:
typhoid, and paratyphoid fevers, dysentery, and cholera.
c. Arthropod-borne Diseases. Transmitted from person to person (or from
animal to person) by arthropods. Examples: malaria, typhus, and yellow fever.
d. Venereal Diseases. Transmitted from person to person by sexual
intercourse. Examples: Syphilis, gonorrhea, and chancroid.
e. Miscellaneous Diseases. Those communicable diseases that do not fall
conveniently into any of the above groups. Examples: tetanus (lockjaw), scabies (the
"itch"), rabies (hydrophobia), and dermatophytosis (athlete's foot).
1-13. ESSENTIALS FOR THE TRANSMISSION OF DISEASE
Each case of communicable disease represents steps in a series of events that
may lead to a new case of disease. Each step in this series is dependent on the
successful completion of the preceding step to form a link in the chain of the spread of
infection. The three links in this chain are (1) the reservoir (source), (2) the vehicle
(means of transmission), and (3) the susceptible person, figure 1-1. If any of the links in
this chain can be broken, disease will not result. Personal hygiene will help break all
three links in the chain of infection, figure 1-2.
Figure 1-1. The chain of disease transmission.