**3.2. Time series of morbidity and mortality of meningococcal infection in Ukraine**

In 1969, an incidence of less than 0.9 per 100,000 people of MI was recorded. Since then, the incidence began to rise and lasted until 1985. For decade (1973–2012), MI incidence (including all clinical forms) ranged from 6.7 (1985) to 0.83 (2012) per 100,000 people. Instead, in the long term, of IMD and mortality appear be very specific and different dynamics, while IMD incidence is much lower and ranges from 2.22 (1974) to 0.75 (2012) per 100,000 people with a mortality from 0.84 (1983) to 0.09 (**Figure 3**).

There is a significant decrease morbidity and mortality of MI for the last 33 years in Ukraine. Between 1983 and 2015 the incidence of MI decreased by 7.2 times. Between 1973 and 2015

**Figure 2.** Etiological structure of purulent meningitis cases in Ukraine (1992–2012). Legend: Abscissa = Time (year); Ordinate = relative percentage of the bacterial meningitis etiology; oblique lines = Meningococcal Infection (MI); vertical lines = Staphylococcal and Other PBM (caused by *Staphylococcus aureus, Streptococcus* groups A and B, *Klebsiella pneumoniae, Escherichia coli, Listeria monocytogenes* and other PBM); horizontal lines = PBM of unknown etiology); points = PBM pneumococcus (Purulent Bacterial Meningitis caused by *Streptococcus pneumoniae*); black = *Haemophilus influenzae* type b (Hib-PBM).

**Figure 3.** Morbidity and mortality dynamics of meningococcal infection in Ukraine of a decade of observation (1973–2015). Legend: Abscissa = time (year); Ordinate = patient meningococcal infection per 100,000 people; line with empty square = Meningococcal Infection (total MI, all clinic forms); line with empty diamond = Invasive Meningococcal Disease (IMD); line with empty triangle = total Mortality of Meningococcal Infection.

the incidence of MI decreased by 5.4 times. In 2012 in Ukraine, IMD incidence (0.75 per 100,000) was comparable to the one of EU (0.7 per 100,000). However, death rate in Ukraine (0.09 per 100,000) was higher than in the EU (0.06 per 100,000). Also, this has to take into account that half of the cases of MI in Ukraine are not bacteriologically confirmed.

#### **3.3. Seasonality of meningococcal infection in Ukraine**

From 1992 to 2015, most IMD cases occurred in winter and spring, as for other respiratory diseases in Ukraine. IMD incidence peaked up in March, while the lowest number of cases was reported in August (**Figure 4**). During that same period of time, 938 cases of IMD were regularly reported on the monthly base, and seasonal increase was registered when the number of monthly cases exceeded 78 (938 cases / 12 month = 78.2 ≈ 78). Seasonal incidence rise was lasted for 6 months (from December to June) with a cumulative total number of 554 cases corresponding 59.06% annual incidence (i.e., seasonal coefficient with regard to the 9.84% average for each of these months. A 334 (40.94%) as of MI cases occurred during the seasonal rise with a monthly increase of 6.82%. One can ultimately evaluate the cases associated with seasonal risk factors that were in 18.66%, i.e. (9.84% – 6.82%) × 6 months = 18.66%.

Thus, the impact of seasonal factors on the annual incidence is very moderate, that is, annual incidence of MI is due to the seasonality of not more than one-fifth of part. Over 80% of

Biosurveillance of Meningococcal Infection in Ukraine, 43 Years of Survey: Spatial and Temporal Dynamics Models http://dx.doi.org/10.5772/intechopen.68371 11

**Figure 4.** Seasonal distribution of meningococcal infection in Ukraine (1992–2015). Legend: Abscissa = time (months); Ordinate = absolute number of cases of meningococcal infection; Gray line = the average monthly number of Meningococcal Infection (MI) cases of long-term; Empty diamond = number of Meningococcal Infection (MI) cases by month.

 incidence of MI depends on the action of permanent factors. Our hypothesis is that the proportion of susceptible population and the frequency of contacts between people (at risk of infection) are the basic are a permanent risk of MI transmission. We also assume that its values are slightly slowly changing throughout the year. Such seasonal rise was observed in Europe from December to June is also characterized by a seasonality pattern as it is in Ukraine, with the highest rate reporting during winter [8].

#### **3.4. Geographical distribution**

the incidence of MI decreased by 5.4 times. In 2012 in Ukraine, IMD incidence (0.75 per 100,000) was comparable to the one of EU (0.7 per 100,000). However, death rate in Ukraine (0.09 per 100,000) was higher than in the EU (0.06 per 100,000). Also, this has to take into

**Figure 3.** Morbidity and mortality dynamics of meningococcal infection in Ukraine of a decade of observation (1973–2015). Legend: Abscissa = time (year); Ordinate = patient meningococcal infection per 100,000 people; line with empty square = Meningococcal Infection (total MI, all clinic forms); line with empty diamond = Invasive Meningococcal

From 1992 to 2015, most IMD cases occurred in winter and spring, as for other respiratory diseases in Ukraine. IMD incidence peaked up in March, while the lowest number of cases was reported in August (**Figure 4**). During that same period of time, 938 cases of IMD were regularly reported on the monthly base, and seasonal increase was registered when the number of monthly cases exceeded 78 (938 cases / 12 month = 78.2 ≈ 78). Seasonal incidence rise was lasted for 6 months (from December to June) with a cumulative total number of 554 cases corresponding 59.06% annual incidence (i.e., seasonal coefficient with regard to the 9.84% average for each of these months. A 334 (40.94%) as of MI cases occurred during the seasonal rise with a monthly increase of 6.82%. One can ultimately evaluate the cases associated with

Thus, the impact of seasonal factors on the annual incidence is very moderate, that is, annual incidence of MI is due to the seasonality of not more than one-fifth of part. Over 80% of

account that half of the cases of MI in Ukraine are not bacteriologically confirmed.

seasonal risk factors that were in 18.66%, i.e. (9.84% – 6.82%) × 6 months = 18.66%.

**3.3. Seasonality of meningococcal infection in Ukraine**

Disease (IMD); line with empty triangle = total Mortality of Meningococcal Infection.

10 Meningoencephalitis - Disease Which Requires Optimal Approach in Emergency Manner

The incidence of MI is unevenly distributed on a geographical ground and expressed by ANOVA MI incidence for the 1992–2013 period of times among administrative units of Ukraine. Estimated value (Fisher's test = 8.52, > critical value of 1.52) rejects the null hypothesis of no effect of geographical factors on the incidence of MI. Indeed, **Figure 5** shows the uneven geographical distribution of the disease by administrative units with low, medium, and high levels of incidence.

At first, the geographical distribution of MI incidence depends on population age pyramid including, the total population of the study area, the urban population and the child population of 0–14 or 0–4-year old. We therefore calculated the corresponding correlation coefficients, but ultimately lacked of statistical significance between prevalence and administrative units. MI incidence correlation coefficients, when compared to different group, were equal to: 0.3260 versus population density; 0.036 versus total population; 0.1711 versus urban population percentage; 0.1370 versus children aged 0–14; and 0.1968 versus the children aged

**Figure 5.** Incidence of meningococcal disease in Ukraine by oblast (1992–2013). Legend: light-gray = Low incidence of Meningococcal Disease (less than 25 percentiles, IR<1.69); moderately gray = Middle incidence of Meningococcal Disease (between 25 and 75 percentile, IR = 1.69 ÷ 2.18); gray = High incidence of Meningococcal Disease (higher 75 percentile, IR > 2.18).

0–4 years. We believe that the lack of statistical significance between these indicators suggest sporadic (or random) spatial nature distribution of the disease. Also, ANOVA analysis shows significant differences in the incidence among oblasts, but the correlation analysis of individual factors (population density, age structure, etc.) by oblasts did not show any incidence because the population density and age structure are indirect factors. Thus, we can assume that geographical factors of each individual territory are quite stable, while geography has a limited effect on changes in incidence of MI in Ukraine. Geographical distribution of MI incidence is useful for comparing performance in different areas, but it cannot account for observed differences more likely linked to the multicomponent result with other causal factors. Also, the variable power of causal factors in any oblast could explain the differences in the incidence oblasts. In our case, the geographical distribution of the incidence of MI is a little informative because do not allowed to identify direct factors (i.e., risk of infection and/or risk of susceptibility).

#### **3.5. Age distribution**

The total incidence of MI decreased over the study period in Ukraine among all age groups, while it remains the highest among young children (**Figure 6**).

In Ukraine, the proportion of MI infected children under 14 years represented 77.17% of all cases as compared to 49.81% among the same xc of age of other European countries at Biosurveillance of Meningococcal Infection in Ukraine, 43 Years of Survey: Spatial and Temporal Dynamics Models http://dx.doi.org/10.5772/intechopen.68371 13

**Figure 6.** Dynamics of the incidence of meningococcal infection in Ukraine by age group (1990–2014). Legend: Abscissa = time (year); Ordinate = person with meningococcal infection per 100,000 people by age group; Triangle = Incidence of Meningococcal Disease among the population aged over 15 years; Square = Incidence of Meningococcal Disease among children aged 0-14 years; Diamond = Incidence of Meningococcal Disease among the total population.

large [8]. Thus, children under 14 years in Ukraine are at a major risk for MI infection, and mortality rates account for 78.35% (**Figure 7**). Altogether, there is a strong direct relationship of MI incidence among age groups that exactly fit the local pyramid of age.

0–4 years. We believe that the lack of statistical significance between these indicators suggest sporadic (or random) spatial nature distribution of the disease. Also, ANOVA analysis shows significant differences in the incidence among oblasts, but the correlation analysis of individual factors (population density, age structure, etc.) by oblasts did not show any incidence because the population density and age structure are indirect factors. Thus, we can assume that geographical factors of each individual territory are quite stable, while geography has a limited effect on changes in incidence of MI in Ukraine. Geographical distribution of MI incidence is useful for comparing performance in different areas, but it cannot account for observed differences more likely linked to the multicomponent result with other causal factors. Also, the variable power of causal factors in any oblast could explain the differences in the incidence oblasts. In our case, the geographical distribution of the incidence of MI is a little informative because do not allowed to identify direct factors (i.e., risk of infection and/or risk

**Figure 5.** Incidence of meningococcal disease in Ukraine by oblast (1992–2013). Legend: light-gray = Low incidence of Meningococcal Disease (less than 25 percentiles, IR<1.69); moderately gray = Middle incidence of Meningococcal Disease (between 25 and 75 percentile, IR = 1.69 ÷ 2.18); gray = High incidence of Meningococcal Disease (higher 75 percentile,

12 Meningoencephalitis - Disease Which Requires Optimal Approach in Emergency Manner

The total incidence of MI decreased over the study period in Ukraine among all age groups,

In Ukraine, the proportion of MI infected children under 14 years represented 77.17% of all cases as compared to 49.81% among the same xc of age of other European countries at

while it remains the highest among young children (**Figure 6**).

of susceptibility).

IR > 2.18).

**3.5. Age distribution**

**Figure 7.** Mortality of meningococcal infectious disease among you children by class of age (Ukraine, 1965–2012). Legend: Legend: Abscissa = time (year); Ordinate = person with meningococcal infection per 100,000 people by age class; Empty circle = Incidence of Meningococcal Disease among children aged 0-14 years; Square = Incidence of Meningococcal Disease among children aged 0-1 years; Diamond = Incidence of Meningococcal Disease among the total population; Triangle = Incidence of Meningococcal Disease among children aged 0-4 years.

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

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 children was 0.9420.

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 birth rates or a "baby boom."

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 these groups.

**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 population.
