Diseases of the respiratory tract are caused by direct inhalation of infectious microorganisms which are carried on airborne droplets or dust particles. These bacteria and viruses may also be indirectly transmitted through ingestion by the use of common cups, food utensils, cigarettes, etc. Some diseases which can be spread in this manner are influenza, common colds, diphtheria, rubella, rubeola, pneumonia, scarlet fever, strep throat and tuberculosis. Symptoms range from mild fevers to permanent incapacitation. Avoidance of overcrowding and close physical contact is ideal but will be dictated by the tactical situation.
Arthropods transmit many communicable diseases.
Diseases transmitted by these vectors may include malaria, yellow fever, sandfly fever, typhus, plague, spotted fever, dengue and hemorrhagic fevers. Troop morale and major operations will be adversely affected, and relapse and extended recovery time can be anticipated with these diseases. Mechanical transmission is the carrying of disease agents on or in the body of the vector with deposition on food, water, open sores or soil which is inhaled as dust. Biological transmission occurs when a vector ingests the disease agent by feeding on an infected person or animal. At this point, the infectious agent can remain the same, multiply, and transform within the body of the vector.