SMALL-PDX (a) Infective Agent.—Unknown, but it is a filterable virus.
(b) Source of Infection.—Typical or atypical cases in the active or prodromal stages.
(c) Exit of Infective Agent.—In the secretions of the mouth and nose (possibly the feces and urine) and discharges from the lesions.
(d) Routes of Transmission.—By direct or indirect personal contact, and possibly by flies.
(e) Incubation Period.—Ordinarily 12 to 14 days, sometimes 21.
(f) Period of Communicability.—From the first appearance of symptoms until the disappearence of all scabs and crusts.
(g) Entrance of Infective Agent into the Body.—Probably through the nose.
(h) Methods of Control.—The Infected Individual.—I. Diag nosis: By the clinical manifestations. Differentiation of a typical cases from chicken-pox may be achieved by the Tieche test.
2. Isolation: Hospital isolation in screened wards is pref erable, continued until the period of communicability is over.
3. Immunization of contacts: By vaccination. There is no means of employing passive immunization.
4. Quarantine: Segregation of all exposed persons for 21 days from the date of last exposure, or until protected by vaccination.
5. Concurrent disinfection: Of all discharges and articles soiled therewith.
6. Terminal disinfection: Thorough cleaning and disinfec tion of the premises.
General Measures.—i. General vaccination of all persons in infancy, revaccination on entering school, and of the entire population when the disease is prevalent.
Small-pox Vaccination.—(a) The importance of this means of protection, as well as the possibility of serious or untoward results from its application, demand its consideration in some detail.
(b) Glycerinated virus, put up for distribution in capillary tubes and which has been stored in a refrigerator, should only be employed. One should be sure the date of expiration has not passed, as it is exceedingly important to use fresh, potent virus.
(c) Select for vaccination the left arm at the insertion of the deltoid. Cleanse the arm thoroughly by rubbing with green soap, wash with water, and follow with alcohol. Allow the skin to dry. With a flamed needle make three parallel scratches about i to 3Z inches long and inch apart, taking care not to draw blood. Expel the contents of vaccine tube on the two outer scratches and with shaft of the needle rub the virus well into scratches. Allow to dry for to to 15 minutes. Upon appearance of the eruption it may be covered with a sterile dry dressing.
(d) Course of Eruption in a Primary Take.—(a) Period of
Incubation.—This is from 3 to 4 days duration. The inocula tion scratches will have entirely healed in two or three days.
(b) Period of Papule.—Along the site of the inoculation scratches one or more small, round, flat, bright red and super ficial papules make their appearance. These may be confluent.
(c) Period of Vesicle.—On the fifth day a small clear vesicle will appear in the center of each of the papules. The area around the vesicles becomes red and swollen and enlarges as the vesicle enlarges. The vesicle is multilocular and umbili cated. It is mature by the eighth day.
(d) Period of the Pustule.—By the ninth day the center of the vesicle becomes pustular, the skin is swollen, hot, and fever ish, and the axillary glands are enlarged. The areola com mences to fade by the ninth day.
(e) Period of Scabbing.—By the iith to Izth day the pustules begin to dessicate and form a scab, which falls off after 2 to 3 weeks, leaving a red scar, which later turns white.
(e) The general symptoms are most noticeable during the stage of pustulation. One may observe malaise, loss of appe tite, nausea and vomiting, headache and muscular pain, with to 2 degrees of fever, which lasts from 3 to 7 days.
Immunity appears on the eighth day, and lasts on the average approximately seven years. The best time to vaccinate for the first time is in the first year of life before the second summer.
(f) Re-vaccination may: (a) Run a course resembling the primary take. In this event the cow-pox immunity has disappeared, or, (b) Run a slightly more rapid course (Accelerated Reaction). The incubation period is short and pustulation occurs by the sixth day, or, (c) With an incubation period of 24 hours or less, an imme diate reaction, which presents a small papule or erythema that later fades, may occur in immune persons.
(g) Vaccination of Exposed Persons.—(a) If done during or immediately before the primary fever of small-pox it does not influence the disease nor does it take.
(b) If done in the last stages of the small-pox incubation period it takes, but the two infections run a simultaneous course without influencing each other.
(c) If done during the 6th to 8th day of incubation, so that its eruption is mature before the onset of small-pox, it will prevent or abort the disease.
individuals in whom the vaccination immunity is waning may contract small-pox, but the disease will run a very mild course (varioloid).