Spread of Infection in Schools.—One of the chief duties of those doctors first appointed by education authorities was to take steps to arrest the spread of infections in schools. As a factor in the transmission of infectious diseases school attendance is not so important to-day as in the past when there was more crowding in rooms which, because of the small windows and inefficient heating, were poorly ventilated. While the influence is still great in the case of such diseases as measles, attendance at school is not to-day a factor of importance in the spread of scarlet fever and diphtheria.

In measles and other diseases to which all are subject, school attendance causes infection because it may be the first occasion the children have congregated with others, and so for many it will be the place in which they are first brought into contact with spreaders of infection. The dormitories of boarding-schools might favour spread.

School Closure and Exclusion from School.—Local sanitary authorities have for long been empowered, acting on the advice of the M.O.H., to close schools with the object of preventing spread of disease or danger to health. These powers have now been withdrawn, the requirements now being that a pupil shall not be refused admission to, or be excluded from, school on other than reasonable grounds. In urban communities the children will probably congregate elsewhere, so that contact is not avoided by closing the school.

On the other hand, closure lessens the possibility of detecting the source of the infection, and also reduces the likelihood of detection of fresh cases in the earliest stage. As a general rule, then, school closure is not practised, though there may be special occasions when it is advisable, such as the outbreak of a severe infection in a rural school, in which case the school would provide the only place for contact of the healthy with the spreaders ; or sometimes it may be advisable when an outbreak occurs in a boarding-school.
T h e local education authority can authorize the exclusion of any child to prevent the spread of disease or on the grounds that the uncleanly or verminous condition is detrimental to other children. In practice children suffering from infectious diseases are excluded, and sometimes their contacts. The period of exclusion varies for different diseases. T h e Memorandum on School Closure and Exclusion from Schools issued by the Ministry of Health and the Board of Education recommended the procedure to be followed by authorities in regard to exclusion for infectious diseases. Up to recently contacts were excluded for quite lengthy periods. When the infectious patient had been removed to hospital, the contact was excluded for a period longer than the longest known period of incubation of the disease. If the patient were treated at home, the period of exclusion ran from the date that the patient was declared free from infection or from the time the premises were disinfected. T h e most recent issue of the Memorandum has considerably modified these recommendations. Exclusion of a contact is now for a period just longer than the longest common period of incubation ; while the period of exclusion of the contact of the patient treated at home now runs from the date the patient is effectively isolated. These changes, which have been made possible perhaps by a reduced infectiousness of the disease and have taken into account their diminished severity, have resulted in a considerable reduction in the waste of school- time of the children, without having been followed by any increased spread of the infections.

The following is a summary of the recommendations contained in the Memorandum, the suggested period of exclusion relating to contacts at day-, but not necessarily at boarding-, schools.
SCARLET FEVER.—
Incubation Period.—ι to 7 days.
Exclusion.—
Infected child : 7 days after discharge from hospital, or
from home isolation.
Contact : 7 days after removal of patient to hospital or
the beginning of his isolation at home. DIPHTHERIA.—
Incubation Period.—2 to 7 days. Exclusion.—
Infected child : Until pronounced by a medical practitioner to be free from infection.
Contact : 7 days after the removal of the patient to hospital or the beginning of his isolation at home.
MEASLES.—
Incubation Period.—7 to 14 days.
Exclusion.—
Infected child : 14 days after appearance of rash if the
child appears well.
Other children in house : Those attending Infants’ Depart-
ment and those who have not had the disease : exclude for 14 days from onset of last case in home. Those who have previously, suffered are not excluded.
Spread in School.—Infection is short-lived, and is not commonly conveyed by healthy persons. Spreads when there are in the class 30 to 40 per cent of susceptibles, and continues till this figure is reduced to 15 or 20 per cent. Course in school is usually a first crop of secondary cases after 12 days, and then another crop after another 12 days.
Closure.—Class closure is unsatisfactory. If closure is adopted, best method is closure for 5 days, starting on 9th day after onset of first case. On opening, exclude those suffering, and those contacts in Infants’ Department, or those who have not had measles.
GERMAN MEASLES.—
Incubation Period.—5 to 21 days.
Exclusion.—
Sufferer : 7 days from date of appearance of rash.
Contact : None.
WHOOPING-COUGH.—
Incubation Period.—6 to 18 days.
Sufferer : 28 days from beginning of characteristic cough. Contact : Infants who have not had the disease 21 days
from date of last exposure to infection.
Advisable during epidemic to exclude all children suffering
from severe cough, whether whooping or not. CHICKEN-POX.—
Incubation Period.—11 to 21 days. Exclusion.—
Sufferer : 14 days from date of appearance of rash. Contact : None.
SMALL-POX.—
Incubation Period.—10 to 21 days.
Exclusion.—
Sufferer : Until pronounced by medical practitioner as free from infection.
Contact : 21 days unless recently successfully vaccinated, when exclusion unnecessary.
MUMPS.—
Incubation Period.—12 to 28 days.
Exclusion.—
Sufferer : 14 days from onset of disease or 7 days from
subsidence of swelling.
Contact : None.
INFLUENZA.—Children usually suffer after adult in family
has been attacked. Schools are probably not an important factor in spread.
Exclusion of Sufferer.—For period of attack. Should be medically examined before admission.
86 PUBLIC HEALTH
PULMONARY AND OTHER OPEN TUBERCULOSIS.—Exclude sufferers.
CEREBROSPINAL FEVER ; POLIOMYELITIS ; ENCEPHALITIS LETHARGICA.—
Exclusion.—
Sufferer : Any child with signs of mild or abortive attack to be excluded for minimum of 6 weeks.
Contact : 3 weeks from isolation of patient.
Those who have suffered from an infectious disease, or their contacts, will return to school after these periods of exclusion only if presenting no abnormal or suspicious signs.

E.W Caryl Thomas, 1948