Eurosurveillance

ECDC

Meningococcal Disease in Lithuania: Trends in Incidence and Dominant Serogroups

 Rediger
  Published: 14.05.04 Updated: 29.07.2004 14:47:39
Dalia Rokaite, Centre for Communicable Disease Prevention and Control, Lithuania

In Lithuania during the period from 1998 till 2002 the incidence of meningococcal disease was moderate compared with other European countries, and case fatality rate reached 9.8%. During this period 62-77 cases of meningococcal disease were registered annually in Lithuania (incidence rates 1.65-2.20 per 100 000). The incidence was slightly lower compared with the early 1990s, but meningococcal disease remained an important communicable disease problem, especially among young children. While serogroup B was clearly dominant during 1998-2002, several cases (slightly more than usual) caused by N. meningitidis C were reported in early 2003.

Introduction

Two main serogroups of N. meningitidis are responsible for majority cases of the disease in European countries. In 1999/2000, B and C serogroups caused 95% of the cases (1). Since the conjugate serogroup C meningococcal vaccine is now available and recommended by WHO (2), and already used in some countries for routine immunisation (1,2) or outbreak control (3), the incidence and distribution of the main serogroups is an important aspect of surveillance.

In Lithuania the conjugate serogroup C meningococcal vaccine has been available since the beginning of 2003. However, the number of children vaccinated with this vaccine during the first six months of 2003 was still very small. The polysaccharide vaccine against A and C meningococci is primarily given to travellers elder over 18 months of age visiting countries where outbreaks are common.

Methods

In Lithuania patients with suspected meningococcal disease are usually hospitalised at infectious disease clinics or departments in Vilnius, Kaunas, Klaipeda, Siauliai or Panevezys. Blood and/or cerebrospinal samples are taken for laboratory identification of Neisseria meningitidis using isolation and/or antigen detection methods. Microscopy (demonstration of Gram negative diplococci) is also used as a method for laboratory confirmation. Every case of invasive meningococcal disease (including meningitis and/or septicaemia) confirmed by laboratory diagnosis or diagnosed according to clinical symptoms, is reported to public health centres and to Centre for Communicable Disease Prevention and Control. Annual compilation forms for meningococcal disease are completed by public health centres and sent to Centre for Communicable Disease Prevention and Control.

Results

According to the data collected, a total of 347 meningococcal disease cases were notified in 1998-2002. One hundred thirty cases (37%) were confirmed by laboratory analysis and 79 (23%) cases of serogroup of N. meningitidis were detected. The highest number of cases was observed during the first quarter. In 1998-2002, 34 fatal cases of the disease were registered (case fatality rate 9.8%). However, the percentage of laboratory-confirmed cases of meningococcal disease was comparably low, and a number of serious and even fatal cases were reported without laboratory confirmation or serogroup detection.

As usual, the highest incidence rate was reported among young children. Almost 75% of the cases were diagnosed among 0-4 year olds, and the incidence rate was comparably high in this age group, especially in children under 1 year (Fig.1).

Serogroup A that is commonly associated with the highest case fatality rate (1) was very rare (Table 1). Since the beginning of 1998 only two cases of serogroup A were reported, of which one was fatal. In November 1998 a 15 year old female died after developing purpura fulminans. The last case of serogroup A was detected in January 2001 in a 4 month old child who survived following treatment. No foreign contacts were associated with these two cases.

Table 1. Cases of meningococcal disease by age and serogroups, 1998-2002 /

 

Age

Serotype

   

Total, with detected group

Total confirmed cases

Total notificated cases

 

A

B

C

C/W135

Y

     

<1 y

1

27

1

3

 

32

37

113

1-4y

 

16

4

1

 

21

39

114

5-9y

 

2

2

1

1

6

8

37

10-14y

 

5

     

5

8

14

15-19y

1

3

1

   

5

8

13

20-25y

   

1

   

1

6

7

25-44y

 

2

1

   

3

7

17

45-64y

 

1

     

1

10

22

65+

 

5

     

5

7

10

Total

2

61

10

5

1

79

130

347

% of total with detected group

2,5

77,2

12,7

6,3

1,3

100

   

Serogroup B was clearly dominant causing 77% of all cases. N. meningitidis B was even more frequent in children under 1 year of age (83% of cases), and was slightly lower (76 % cases) and similar to the overall distribution in the 1-4 year old age group.

The number of cases caused by serogroup C was almost 6 times lower than serogroup B and there were only 10 cases (13 %) confirmed as N. meningitidis C. In addition, 5 cases were reported as C/W135 since, in some cases, N. meningitidis was not completely subgrouped. During the 5-year period (1998-2002) an average of only 2-3 cases of serogroup C were registered annually, mainly in the 1-4 year age group. However, in this age group the annual number of serogroup C cases and the incidence rates were also low (1-2 cases, 0.5-1.0 per 100 000). Only a small number of serogroup C cases was detected among children under 1 year (average annual incidence rate was 0.6-2.2 cases per 100 000). Case fatality rate was relatively low for both N. meningitidis B (4.5%) and N. meningitidis C (6.7%). However, a large proportion of the fatal cases was not confirmed by laboratory analysis or serogroup detection.

When summarising data by serogroups it should be taken into account that there was a significant number of confirmed cases with undetected serogroup (51 cases or 15 % of all notified cases), and a significant number of notified cases without laboratory confirmation (217 cases or 63% of all notified cases). It may be assumed that the actual number of B and C serogroup cases during 1998-2002 period was 1.5-4 times higher than the number of registered cases. Thus, the incidence rate of meningococcal disease caused by serogroup C in age groups under 1 year and 1-4 year would not be significantly lower than the average incidence rate in European countries: 2.3 per 100 000 among 1-4 year olds and 3.3 per 100 000 among children under 1 year in 1999/2000 (1).

During the first quarter of 2003 an increase in the number of serogroup C cases was observed (Fig. 2). The numbers of serogroup B and C cases were almost equal, while the number of reported cases of meningococcal disease cases remained at the usual seasonal level. Five cases caused by serogroup C and one case notified as C/W135 were reported from four territories (3 cases in Kaunas town). All of these cases were diagnosed among young children: 5 cases among 1-4 year olds and 1 case in a 5 month old child. According to public health data, no epidemiological link was revealed in these cases.

Discussion

In Lithuania during the 1998-2002 period the number of registered meningococcal disease cases was not high and the incidence was intermediate as compared with other European countries. The incidence was highest in the first quarter of the year as in most European countries (4). A rather small number of C serogroup cases were identified, and serogroup B was clearly dominant. However, some cases caused by N. meningitidis C were reported among young children during the first quarter of 2003. Although number of N. meningitidis C cases has not increased significantly, certain changes in the proportion between B and C cases may be revealed in 2003. Should an increase in the proportion of N. meningitidis C cases be observed, the conjugate serogroup C meningococcal vaccine could be recommended for young children.

References

  1. N. Noah, B. Henderson. Surveillance of bacterial meningitis in Europe 1999/2000. CDSC European Bacterial Meningitis Surveillance Project. http://www.phls.org.uk/topics_az/meningo/m_surveillance9900.pdf (abridged version)
  2. Meningococcal vaccines: polysaccharide and polysaccharide conjugate vaccines, Weekly Epidemiological Record, 2002; 77: 331-339.
  3. D. Lèvy-Bruhl, A. Perrocheau, M. Mora et al. Vaccination campaign following an increase in incidence of serogroup C meningococcal diseases in the department of Puy-de-Dõme (France), Eurosurveillance Monthly 2002; 7: 74-76.
  4. M. Ramsay, E. Kaczmarski, M. Rush et al. Changing patterns of case ascertainment and trends in meningococcal disease in England and Wales, CDC Weekly 1997; 7: 49-54.

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