Meningococcal disease in the faroe islands

Meningococcal Disease in The Faeroe Islands
by I. Lind, H. D. Joensen, J. Poolman and H. Zoffmann


Meningococcal Disease in The Faeroe Islands
by I. Lind, H. D. Joensen, J. Poolman and H. Zoffmann
Introduction
The Faeroe Islands are a cluster of 18 small islands situated in the Atlantic Ocean, north of Great
Britain. Seventeen of the islands are populated (per 31.12.83: 44.805 inhabitants). Since 1948 the
Faeroe Islands have been an autonomous community allied to Denmark.
Epidemiology
In 1977 three cases of meningococcal disease were notified in the Faeroe Islands (incidence
7/100.000).
During the following years an epidemic of meningococcal disease developed; a peak incidence of
95/100.000) was reached in 1981; table 1 shows that meningococcal disease has since then occurred
at a hyperendemic level (56-69/100.000). By statistical analysis of figures from the period 1981-
1984 it was demonstrated that there was a significant difference between number of cases notified
from the various islands (range 21/100.000 – 142/100.000); Within a particular area no year-to-year
variation could be demonstrated. The age specific incidence for infants below one year of age was
extremely high and for children 0-4 years of age it was as high as 400 – 450/100.000 (table 3). The
case fatality rate for the period 1977-1984 was 5.5% (11 deaths).
Laboratory investigations
Serological grouping of Neisseria meningitidis isolates from patients with meningococcal disease
was established in 1980. The bacteriological examination of clinical specimens is performed locally.
All meningococcal cultures were sent by air-mail in a modified Stuart’s medium to the Neisseria
Department, Statens Seruminstitut, Copenhagen. Serological grouping was performed by means of
a co-agglutination test using rabbit antisera against N. meningitidis serogroup A, B, C, W-135, 29E,
X, Y, and Z coated on protein A-rich Staphylococcus aureus cells as carriers. Determination of
serotype 2a, 2b and 15 was performed similarly using type-specific monoclonal antibodies. Selected
strains were subtyped regarding class 1 outer membrane proteins by SDS polyacrylamide-
gelelectrophoresis. The in-vitro susceptibility to sulphonamide and penicillin was determined by a
plate dilution method and the susceptibility to rifampicin by an agar disc diffusion test.

Årsberetning 1985, Bilag II, side 59-76
Landslægen på Færøerne
Udarbejdet af Landslæge Høgni Debes Joensen, Tórshavn 1986

Meningococcal Disease in The Faeroe Islands
by I. Lind, H. D. Joensen, J. Poolman and H. Zoffmann


Serogroups:
During the five-years period studied the percentage of group B strains was high (82%-95%). With
one exception the remaining strains belonged to serogroup C (table 1).
Serotypes:
The results of serotyping of group B strains are shown in table 2. Among group B strains there was
a strong predominance of type 15. An indication of an on-going evolution could be implied from
the occurrence of only one strain type 2b in 1980 and the later coincidence of a decline in the
occurrence of type 15 strains and the emergence of non-typable strains (table 2). Three strains
received in the beginning of 1985 were type 15. Subtyping of 19 group B, type 15 strains from
1980-1982 showed the presence of the P1. 16 class 1 protein in 18 out of the 19 strains (95%).
Antimicrobial susceptibility:
Group B strains were resistant (MIC’s ≥ µg/ml) to sulphonamides and group C strains were
susceptible. All strains were susceptible to penicillin and rifampicin.
Demand for vaccination
The continued and marked increase in the prevalence of meningococcal disease caused by group B,
type 15 meningococci during the winther of 1980-1981 made it clear that this situation could be
handled only if a group B, type 15 vaccines were available. The fact that the incidence of disease
has remained high in spite of a very efficient clinical surveillance seems to confirm this statement.
A suitable vaccine is not commercially available and it was therefore considered whether a
controlled vaccine trial would be acceptable; the target group should then be children 0-4 years of
age (about 4.000 individuals); the remaining population (40.000 individuals) could serve as a
reference group since the number of cases within this group has been fairly constant and of the
same magnitude as tat in the group of children 0-4 years of age (table 3). The question is whether
the emergence of non-typable strains during 1984 has removed the possibility for carrying out such
a trial?

Årsberetning 1985, Bilag II, side 59-76
Landslægen på Færøerne
Udarbejdet af Landslæge Høgni Debes Joensen, Tórshavn 1986

Meningococcal Disease in The Faeroe Islands
by I. Lind, H. D. Joensen, J. Poolman and H. Zoffmann


Meningococcal Disease in the Faeroe Islands
Year Incidence
Number of
Number of strains of serogroup
notified meningitidis
strains *
* one isolate per case included; NG = non-groupable Meningococcal Disease in the Faeroe Islands
N. meningitides strains *
Number of group B strains of serotype
Year Total
(%) 2a 2b 15 NT
1980 18 17 (95) 0 1 16 0 1981 22 19 (86) 0 0 19 0 1982 11 9 (82) 0 0 8 1 1983 18 16 (88) 0 0 12 3 1984 15 13 (87) 0 0 9 4 * one isolate from each case included; NT = non-typable
Årsberetning 1985, Bilag II, side 59-76
Landslægen på Færøerne
Udarbejdet af Landslæge Høgni Debes Joensen, Tórshavn 1986

Meningococcal Disease in The Faeroe Islands
by I. Lind, H. D. Joensen, J. Poolman and H. Zoffmann


Meningococcal Disease in the Faeroe Islands:
Distribution of patients according to age
Number of notified cases in
1980 1981 1982 1983 1984

Årsberetning 1985, Bilag II, side 59-76
Landslægen på Færøerne
Udarbejdet af Landslæge Høgni Debes Joensen, Tórshavn 1986

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