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Five of the cases in this outbreak resulted from a gravis strain all virulent.
The remaining case (case 7) did not have a positive swab and was diagnosed on the history
and on clinical grounds, namely palatal and ocular pareses.
Only in the sister and brother, (cases 13 and 14) in December, and the mother and
son (cases 5 and 6) in May was there direct evidence of cross connection between the cases.
In some of the cases the school attended by the children appeared to be the only
common factor.
It is, however, interesting to note that of the three cases attending Holbrook
County Secondary School, that occurring in February gave an intermedius strain, while those
in May and December were gravis strain. Similarly, of the two cases at Napier County Primary,
one in July was an intermedius strain while the other in December was a gravis strain.
Immunisation.
A matter of interest is the immunisation state of the children in the two outbreaks.
In the second, outbreak only one of the children was "stated by parent to have been
immunised in infancy". In the remaining five cases there is a record of each having been
given a primary immunisation within the previous five years. Table II shows the dosage and
antigens used. Only one of these children is "stated to have had a booster", but no record
is available.
However, in the earlier outbreak the picture is somewhat different. Here, only one
of the children had been immunised previously (3x1 c.c. D.P.P. in 1954)• The remainder
were "stated by parent to have been immunised in infancy". One of these children had a
reinforcing dose of 0.5 c.c. A.P.T. in 1954
Investigations.
The same investigations were carried out in the second outbreak as in the first and
suitable precautions were taken. Throat and nose swabs were taken in 268 family and school
contacts and no pathogenic organisms were isolated.
Enquiries as to possible common sources of infection from milk, ice cream and other
foodstuffs were made, but all proved negative.
Immunisation Campaign.
By the end of December it was evident that the disease was resulting from a
particularly virulent gravis type, having broken through comparatively recent immunisations
(two in 1954, one in early 1955 and one in 1951 with a 'booster' in 1954) All six cases
had occurred in the West Ham Ward or adjacent areas and attended five different schools in
that area.
It was, therefore, decided to endeavour to secure the immunisation or re-immunisation
of all school and pre-school children in this area.
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