**3.7. Meningococcal carriage**

The correlation coefficient between the total number of cases of MI and the number of population for the years was r = 0.9676 (1990–2014). The correlation coefficient between the overall

The correlation coefficient between number of the MI cases among children 0–14 years of age and number of children was of 0.9531. The correlation coefficient between the MI incidence among children 0–14 years of age and number of children was of 0.8163. The correlation coefficient between the total incidence of MI and the number of children was 0.9239. The correlation coefficient between the total number of cases of MI and the number of chil-

All of the above present a direct and strong statistical correlation between the dynamics of age structure, the population and the incidence of MI. Peak incidence and mortality of meningococcal disease occurred in Ukraine in the mid-80s, also corresponding to this time of national

Children's age is an indirect risk factor for invasive meningococci disease (IMD), while youngest children are more susceptibility to the pathogen, including predisposing factor of IMD and high transmission risk among over-crowded communities (i.e., school, recreation area, etc.). Incidence may also be reduced when the relative number of children decreases, and the whole population is aging (as it is in Ukraine and Europe). Indeed, during the study period, the number of children relatively decreased by twofold among general population, while the total number of population also decreased in Ukraine. Thus, we believe that the incidence of IMD in different age groups defined different levels of susceptibility of the pathogen for

**Figure 8.** The dynamics of relationship between the overall incidence of meningococcal infection and the general population (Ukraine, 1990–2014). Legend: Abscissa = time (year); Ordinate = case of meningococcal infection per 100,000 people; Diamond = number of the total population; Triangle = Incidence of Meningococcal Disease among the total

incidence and the total population was r = 0.9556 (**Figure 8**).

14 Meningoencephalitis - Disease Which Requires Optimal Approach in Emergency Manner

dren was 0.9420.

these groups.

population.

birth rates or a "baby boom."

Indeed, as a first factor in favor of such observations, one has to consider that meningococcus carriage is the most widespread form of meningococcal infection, that is, for one patient with IMD there is an estimate of more than thousands asymptomatic carriers of the pathogen. Carriage rates can range between 1 and 50% while varies with age, socioeconomic status, and connected with the predominant strain circulating in the area, and a number that appears not to vary with season or herd immunity. However, nasopharyngeal carriage surveillance is not recommended neither reported as a practical useful public health tool [9]. Also, data on nasopharyngeal carriage are available from state bacteriological laboratory in Ukraine (Ukrainian Centre for Disease Control and monitoring of the Ministry of Health of Ukraine) (**Figure 10**). Indeed, diagnostic tests are run annually by the Sanitary-epidemiological service

**Figure 9.** Dynamics of meningococcal infection in Ukraine in rural and urban areas (1990–2014). Legend: Abscissa = time (year); Ordinate = case of meningococcal infection per 100,000 people; Circle = Incidence of Meningococcal Disease in urban settings; Square = Incidence of Meningococcal Disease in rural; Triangle = Incidence of Meningococcal Disease among total population.

of Ukraine using nasopharyngeal swab. This approach was conducted in order to identify the level of circulating *N. meningitidis* in Ukraine among the healthy children and adolescents and also among all persons who had contact with MI patients, while contact persons represent all age groups or the general population. Such study was carried out in all 26 regions (oblasts) of Ukraine.

From 1992 to 2012, 890,061 people (average of 42,384/year) were investigated, moreover, 482,435 healthy people (average of 23,973/year) of all ages who have had contact with confirmed patients with MI, were also tested for meningococcal carriage in Ukraine. The results of these time series of MI carriers are shown in **Figure 9** and show the risk among healthy children and adolescents as an average of 0.99% as compared to 1.97% of the general population. Ultimately, such risk of infection is a factor of emergence of IMD and determines the level of prevalence of a small percentage of carriers is due to the large stratum of old adults and the low sensitivity of bacterial tests in Ukraine. The risk of infection is a necessary susceptibility factor for the emergence of IMI and therefore constantly determines the level of prevalence of meningococcal carriage.

#### **3.8. Meningococcus serogroup distribution**

In 1992–2012, information on the meningococcus serogroups was reported for 9484 IMD cases in Ukraine. The meningococcus B serogroup was responsible for 48.9% of IMD, followed by the meningococcus A serogroup (15.78%) and the meningococcus C serogroup (13.21%). The meningococcus D, X, Y, Z, 29E and W135 made up to 3.19% of IMD cases. Non-capsular strains represented 18.91%. During that same period, total information on serogroup was reported for 15,868 carriers. The meningococcus serogroup B was responsible for 36.15%

**Figure 10.** Meningococcal carriage dynamics among different population group survey in Ukraine (1992–2012). Legend: Abscissa = time (year); Ordinate = absolute number of carriers of meningococci; Circle = Prevalence (%) of meningococcal carriage among the healthy children and adolescents; Diamond = Prevalence (%) of meningococcal carriage among persons who had contact with MI patients (all age groups or the general population).

of carriers of meningococcal infections, followed by serogroup C (7.74%) and serogroup A (7.17%). The meningococcus serogroups D, X, Y, Z, 29E and W135 represented 6.75% of carriers' meningococcal infections the known serogroup. Not typed strain represented 42.19% of carriers of meningococcal infections (**Figure 11**).

of Ukraine using nasopharyngeal swab. This approach was conducted in order to identify the level of circulating *N. meningitidis* in Ukraine among the healthy children and adolescents and also among all persons who had contact with MI patients, while contact persons represent all age groups or the general population. Such study was carried out in all 26 regions (oblasts)

16 Meningoencephalitis - Disease Which Requires Optimal Approach in Emergency Manner

From 1992 to 2012, 890,061 people (average of 42,384/year) were investigated, moreover, 482,435 healthy people (average of 23,973/year) of all ages who have had contact with confirmed patients with MI, were also tested for meningococcal carriage in Ukraine. The results of these time series of MI carriers are shown in **Figure 9** and show the risk among healthy children and adolescents as an average of 0.99% as compared to 1.97% of the general population. Ultimately, such risk of infection is a factor of emergence of IMD and determines the level of prevalence of a small percentage of carriers is due to the large stratum of old adults and the low sensitivity of bacterial tests in Ukraine. The risk of infection is a necessary susceptibility factor for the emergence of IMI and therefore constantly determines the level of prevalence of

In 1992–2012, information on the meningococcus serogroups was reported for 9484 IMD cases in Ukraine. The meningococcus B serogroup was responsible for 48.9% of IMD, followed by the meningococcus A serogroup (15.78%) and the meningococcus C serogroup (13.21%). The meningococcus D, X, Y, Z, 29E and W135 made up to 3.19% of IMD cases. Non-capsular strains represented 18.91%. During that same period, total information on serogroup was reported for 15,868 carriers. The meningococcus serogroup B was responsible for 36.15%

**Figure 10.** Meningococcal carriage dynamics among different population group survey in Ukraine (1992–2012). Legend: Abscissa = time (year); Ordinate = absolute number of carriers of meningococci; Circle = Prevalence (%) of meningococcal carriage among the healthy children and adolescents; Diamond = Prevalence (%) of meningococcal carriage among

persons who had contact with MI patients (all age groups or the general population).

of Ukraine.

meningococcal carriage.

**3.8. Meningococcus serogroup distribution**

In 2012, information on serogroup was reported for 3234 of confirmed IMD cases in EU countries including 68% of serogroup B, 17% of serogroup C (17%), and a total of 93% included B and C, Y [8]. It is clearly seen that in the EU and also in Ukraine IM case are due mostly to serogroup B, while serogroups B and C are less represented in Ukraine than in EU.

In 2008, serogroup C incidence of was 0.21 per 100,000 in Ukraine. In 2012, it dropped to 0.08 per 100,000. From 2008 to 2012, this index was slightly higher than the 0.1 per 100,000 in EU/ EEA countries [9]. Thus, in the Ukraine, currently, the incidence of serogroup C is not different for EU/EEA but in Ukraine not carried out vaccination against Men C. This fact does not negate the benefits of vaccination but requires further detailed study. When one compares the incidence Men type C in EU with routine vaccination and Ukraine, where routine vaccination against MI has never been carried out, the effectiveness of Men C vaccination appears negligible because the incidence Men type C in EU and Ukraine is not different.

In Europe and Ukraine, decline in the incidence of other serogroups (A and B) was not the result of specific interventions. We believe that demographic situation in Ukraine population has decreased from 52 to 45 million over the past 25 years. Birth rate decreases, and therefore, child population falls, altogether this will certainly not contribute to an increase incidence of IMD in Ukraine for the coming decade. The introduction of routine vaccination of IMD in Ukraine requires careful study because there is limited funding for public health.

**Figure 11.** Distribution of meningococcus serogroups among patients with meningococcal disease (n = 9484) and healthy carriers of (n = 15,868), Ukraine, 1992–2012. Legend: Abscissa = Meningococcus serogroups; Ordinate = cases of meningococcal disease (%); red bar = healthy carriers of MI-pathogen (%); blue bar = patients with meningococcal disease (%).
