(1) There is a definite alteration in the percentage numbers of white blood cells in scarlatina.
(2) The polymorphonuclear cells are much increased
at first and remain over normal in number
until the fourth day when they begin to fall
and rapidly decrease in number until the end
of the first week. In most eases the fall
carries the number of cells well below the
normal figure but in others the figure
reached may be at or about the lower physio¬
The lymphocytes are always few in number at
first. They begin to increase as the polymorphonuclear cells decrease and are found
increased from the 6th to the 8th or 10th
The increase may be of such a degree as to
cause a definite lymphocytosis but more
usually the lymphocyte cells do not increase
more than 10 - 15% above their normal high
physiological figure while occasionally they
are not more numerous than normally.
The eosinophils are few in number until the
4th day. Then they begin to increase rapidly
attaining a maximum on the 5th, 6th or 7th
days and remaining increased until the 9th
day at least.
(3) The changes are most readily observed in a
series of counts carried out from the 4th to
the 8th days.
(4) Under two years of age the series of changes
are very marked, but over that age are less
obvious becoming increasingly less extreme
as the age increases.
(5) All cases of scarlatina except the very severe
(toxic and septic) cases show the same type
of blood changes.
(6) In observation cases diagnosed in hospital
as scarlatina practically every case showed
the characteristic scarlatina blood changes,
while with one or two exceptions the cases
diagnosed as non scarlatinal did not show
(7) The blood examination is of value in diagnosis of observation scarlets, for no other diseases except diphtheria, with serum rash,
and possibly gonorrhoea with a drug rash,
show changes resembling those of scarlatina.
(8) There are exceptional cases, occasionally
encountered which do not follow the usual
laws in relation to blood changes in scarlatina, so that the blood examination cannot
be taken as a perfectly conclusive clinical