64 RELATION OF BACTERIA TO DISEASE 



Persons suffering with an infectious disease are, of course, 

 the greatest danger in communication, but other persons may 

 also carry infection. Attendants upon typhoid, diphtheria, 

 or meningitis patients may carry upon the hands or clothing 

 or in the mouth and nose, bacteria of the respective diseases 

 without themselves having the disease, and may be called 

 "passive" or "accidental" carriers. Doctors and nurses too 

 often are innocently in this class. After recovery from the 

 acute attacks of some diseases, notably typhoid, diphtheria, 

 and dysentery, patients frequently carry the germs for indefi- 

 nite periods; these are called "chronic carriers." Such 

 persons are great menaces and are usually controlled by 

 health authorities when known, but as certain diseases are 

 endemic among us, particularly such conditions as scarlatina, 

 for which the quarantine is very rigid, the number of so-called 

 "hidden carriers" must be very great. Inasmuch as very 

 many infectious diseases are contracted by receiving the 

 virus in the nose and throat from the nasal and pharyngeal 

 secretion of patients, it behooves the nurse and visitors to 

 know this and protect themselves. This is conveniently 

 done by the use of gauze masks over nose and mouth worn 

 both by patient and nurse, especially the latter, since the 

 former should not be made uncomfortable and needs all the 

 air possible. Masking the patient has the advantage of 

 preventing the spread of the virus in the room. 



Bacteria are directly the cause of ptomain poisoning, 

 although the ones concerned may not live within the body. 

 Ptomain poisoning is a violent irritation of the gastro- 

 intestinal tract by certain poisons produced from putre- 

 faction of meat and fish by bacteria. The foods may be little 

 or not altered by these poisonous substances in them. They 

 are in small quantity in the food, but are easily and quickly 

 absorbed. It is possible that for a short time after ingest ion 

 of the meat the formation of these ptomains may continue. 

 Ptomains differ from toxins in that they are formed by 

 altering the chemical composition of the meat rather than 



