London's Pulse: Medical Officer of Health reports 1848-1972

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City of London 1930

[Report of the Medical Officer of Health for London, City of ]

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15
VARIOLA MINOR.
The prevailing type of Small-pox, after long watching, has proved to be a definite type
which keeps its own characteristics even when occurring among populations which have not
been vaccinated, and in which the epidemic is consequently extensive ; it has deserved to
be separately named from the deadlier Small-pox, and is termed Variola Minor. Fatality
in this disease is insignificant, as is seen in the following comparison of Small-pox mortalities:—
England and Wales, Year 1929, fatality .26%.
United States of America, Year 1927, .47%.
Canada, Year 1929, .25%.
Belgian Congo, Year 1929, 2.46%.
Bombay (one week, 1930), 2,013 cases, 1,068 deaths, 53.05%.
British India, Year 1929, 23.2%.
"... judging by epidemiological observations, the varieties of Variola, major and
minor, do not seem to be interchangeable." (Extract of Report from L'Office International
d'Hygiene Publique, quoted in Report of the Vaccination Committee, Ministry of Health,
1930.)
Variola major is extremely dangerous, and variola minor can simulate the major
disease exactly as regards the eruption ; since the population has become used to Variola
minor, which is not dangerous, there is a possibility that contempt of Variola as a whole
may be engendered, with a corresponding contempt of the measures which successfully
combat either variety.
Primary amongst preventive measures is vaccination, and secondary, the observation
of contacts. The infectiousness of Variola minor is sufficiently low that vaccination is
even of greater preventive power in incidence of this disease than in Variola major. One
notices with satisfaction that the affected public, to some extent, realises that the unvaccinated
persons in a family or community are picked out by Variola minor, with a corresponding
realisation of the value of vaccination.
As to observation of contacts, however, the unvaccinated person (i.e., the person most
liable to infection) strongly objects to being " stood off " from work as a contact with a case
during the incubation period of the disease. It is characteristic of the employers in the City
that " standing off " of a contact, in the vast majority of cases, has been accompanied by
full pay. Of course, there is no necessity to " stand off " a contact during the long incubation
period. It is, however, for a trader to decide whether he will or will not do this without
considering dates of possible infection and outbreak in the contact employee, which are
sometimes problematical. I have never advised and would not sponsor such a course
as " standing off." From the trader's point of view, however, the fear of possible dislocation
of trade, consequent on the removal of a case of actual Small-pox from the place of business,
is formidable to many a business undertaking. On the one hand, it would be neither fair
or preventive that the head of the firm should not know the possibilities ; on the other,
lies the resultant possible disability to the contact.
Any contempt of the disease in the minor form may lead to severe difficulty should
the major form appear concurrently with this in the community ; such a state may obtain
at any time, although knowledge and application of vaccination as the one great preventive
measure has spread with astonishing rapidity in those endemic Small-pox centres in the world
which can at once demonstrate the efficiency of the measure, and afford fire for the touchwood
want of vaccination affords. "... it is difficult and imprudent to be dogmatic when
confronted with the early cases as to what kind of Variola one is dealing with." This
quotation from the said report is in reference to an area newly infected with either type of
disease, but would apply with redoubled force to every case if concurrency of the major and
minor disease were threatened or in being.
The conclusion of the report quoted, in reference to Post Vaccinal Encephalitis, emphasizes
the extreme rarity of its occurrence and "... that it should not be allowed in any
way to diminish the confidence placed hitherto in the use of vaccination as a preventive
of Variola " ; further, seeing that the majority of cases occur in children of school age,
"... unless children of school age have been exposed to infection from Small-pox patients,
it is undesirable that they should at that age be vaccinated for the first time."
The approved technique of vaccination now requires one mark only, without cross
hatching, of ¼ inch in length, confined entirely to epidermal tissue and in the long axis of
the limb.
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