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ISSN 2413-6077. IJMMR 2016 Vol. 2 Issue 1

DOI 10.11603/ijmmr.2413-6077.2016.1.6376

EPIDEMIOLOGICAL AND EPIZOOTIC ASPECT OF LEPTOSPIROSIS 
EVOLUTION IN TERNOPIL REGION

N. A. Vasylieva, Yu. A. Kravchuk
I. HORBACHEVSKY TERNOPIL STATE MEDICAL UNIVERSITY, TERNOPIL, UKRAINE 

TERNOPIL REGIONAL LABORATORY CENTRE OF THE STATE SANITATION AND EPIDEMIOLOGICAL 
SERVICE OF UKRAINE, TERNOPIL, UKRAINE

Background. Ternopil region is endemic on leptospirosis. Its natural conditions (slightly alkaline or alkaline 
soils, air temperature, sufficient rainfall) contribute to the existence of major natural reservoir of the pathogen –  
mouse-like rodents. In the region, different serovariants of leptospira are exuded by rodents and farm 
animals. 

Objective. The materials of the Department of Highly Infectious Diseases of Ternopil Regional Laboratory 
Centre of the State Sanitation and Epidemiological Service of Ukraine, Ternopil Regional Laboratory of Veterinary 
Medicine, Clinic of Infectious Diseases of TSMU were studied.

Leptospiras were detected by dark ground microscopy (DFM) of blood of patients, trapped rodents and ex-
amined farm animals.

Results. The circulating of pathogens between different sources (rodents, animals) and annual disease in-disease in-
cidence evidences that new leptospira serovar are carried onto endemic area mostly by farm animals; humans 
are infected from them through the environment sometimes in 3-5 years intervals; the further diffusion to the 
new areas of this pathogen serovars in all kinds of the examined mouse-like rodents is noticed. 

It is established that farm animals and rodents are competing reservoirs. To predict the future epidemio-
logical situation of leptospirosis among the humans and to improve its diagnosis the constant monitoring of the 
population, infection and leptospira carriage among mouse-like rodent and farm animals and expanding of the 
panel of diagnostic leptospira strains including new pathogen variants in animals is necessary.

Conclusions. The development of additional reservoirs in animals, with circulating of other pathogen 
serovars among them, such as mouse-like rodents, which were previously absent in the main natural reservoir, 
cause the change of etiological structure in human leptospirosis at the endemic areas. The range of human 
leptospirosis pathogens and its further spreading among all kinds of rodents increased during our research. The 
results of detection of leptospirosis pathogens among the various contingents which were studied evidence that 
the farm animals and rodents are competing reservoirs that cause human infection through environment.

KEY WORDS: leptospirosis, disease incidence, source of infection, rodents, farm animals.

Introduction
Leptospirosis is a �o��o� i��e�tio�s �is��o��o� i��e�tio�s �is� i��e�tio�s �is�

ease a�o�g h��a�s a�� a�i�als. The �eat�res 
o� this �isease are: �ostly severe �o�rse, high 
�ortality, a�� great so�ial a�� e�o�o�i� losses. 
Every year �ore tha� 1.03 �illio� �ases a�� 
58.900 �eaths happe� ��e to leptospirosis i� 
the worl�. The highest i��i�e��e a�� �ortality 
rate is i� So�th a�� So�theast Asia, O�ea�ia, 
Lati� A�eri�a, East A�ri�a [1]. This �isease was 
re�or�e� i� al�ost all regio�s o� Ukrai�e, i� 
Ter�opil regio� as well.

The �o�se�like ro�e�ts a�� �at�ral �o��i�
tions (slightly alkaline and alkaline soils, suffi­
�ie�t rai��all, appropriate air te�perat�re [2, 
3]) as main natural pathogen reservoir define 
the e��e�i�ity o� leptosirosis area a�� �o�tri�
b�te to preservatio� a�� �isse�i�atio� o� this 
�isease.

The aim o� the resear�h was to i�vestigate 
reg�larities o� epi�e�i� a�� epizooti� pro�esses 
o� leptospirosis a�� st��y it’s pathoge� �ir���
latio� betwee� �i��ere�t �i�i (ro�e�ts, a�i�als) 
a�� perso�.

Materials and Methods
The �aterials o� the Depart�e�t o� Highly 

I��e�tio�s Diseases o� Ter�opil Regio�al Labo�
ratory Ce�tre o� the State Sa�itatio� a�� Epi�
�e�iologi�al Servi�e o� Ukrai�e, Ter�opil Re�

N. A. Vasylieva, Yu. A. Kravchuk

Corresponding author: Nataliya Vasylieva, Department of 
Infectious Diseases and Epidemiology, Dermatology and 
Venereology, I. Horbachevsky Ternopil State Medical University, 
1 Maidan Voli, Ternopil,  Ukraine, 46001
Tel.: +380352524725
E-mail: vasylyeva@tdmu.edu.ua

I�ter�atio�al Jo�r�al o� Me�i�i�e a�� Me�i�al Resear�h 
2016, Vol��e 2, Iss�e 1, p. 28–31
�opyright © 2016, TSMU, All Rights Reserve�



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ISSN 2413-6077. IJMMR 2016 Vol. 2 Issue 1

gional Laboratory of Veterinary Medicine, 
Clinic of Infectious Diseases of TSMU were 
studied.

Leptospiras were detected by dark ground 
microscopy (DFM) of blood of patients, trapped 
rodents and examined farm animals.

Pathogen serovar was determined accord-
ing to serological investigation in microhemag-
glutination test of live leptospira cultures 
(RMAL); standard diagnostic set consisted of 
11 leptospira serogroups that consisted of both 
diagnostic strains proposed by the WHO and 
strains registered in Ukraine and identified in 
accordance with international reference cul-
tures.

The leptospirosis incidence among the hu-
mans in Ternopil region in 1980-2014, leptospira 
contamination of animals at private and collec-
tive farms and also rodents in the wild were 
studied.

Results and Discussion
In Ternopil region there were two rather 

large “bath” leptospirosis outbreaks in children 
(laboratory deciphered L. grippotyphosa) in July 
1963 (18 patients) and in August 1972 (22 pa-
tients). It happened after swimming in the 
river, livestock farms were situated upstream 
of it. The rodents trapped near the river con-
taminated with leptospira too.

Since 1972 regular monitoring of leptospiro-
sis among the humans took place. The lept-
ospirosis incidence among humans in the re-
gion differed: 1,05–12,17 per 100 thousand of 
population (2–149 cases per year); the highest 
rate was in 1992–2001, the maximum incidence 
was in 1994, in 2014 − 3,26, which exceeded the 

average rate in the country all the time and was 
the highest in Ukraine for many years.

Till 1981 L. grippotyphosa was the main 
leptospirosis pathogen in humans (90% cases 
etiologically deciphered). The percentage of 
this leptospira in the structure of leptospirosis 
decreased by 41,1–51,4% in 1988-1989, by 3.4% 
in 1994. From 1999–2000 there were no inci-
dence of leptospirosis caused by this pathogen. 
L. icterohaemorrhagiae was the main etiologi-
cal factor of this disease in the 90s (in 1991 − 
93,2%, in 2000 − 100,0%). 

The disease was rarely caused by other 
leptospira serogroups. The disease caused by 
L. hebdomadis (5,9–45,4%), L. canicola (14,2–
60,0%), L. pomona (3,1–21,4%) was registered 
in 2002; the rate of L. icterohaemorrhagiae 
decreased by 37.5%, there were only some rare 
cases of L. grippotyphosa (Fig. 1). The rate of 
combined leptospirosis significantly increased 
in recent years (34.3% of all registered in 
2014).

The etiologic spectrum of leptospirosis in 
humans and in mouse-like rodents in the first 
stage of observation did not coincide (1981–
1993). In the natural habitats the antibodies to 
leptospira of Grippotyphosa serogroup were 
found in mostly different kinds of voles, field 
and house mice; only to Icterohaemorrhagiae 
– in domestic grey rats. Hebdomadis segroup 
was also found in voles and mice and at home 
foci as well. During the same period the disease 
caused by the above mentioned pathogens as 
well as Canicola and Pomona (1982) (Fig. 1), 
further Kabura (2005) Polonica (2007), was 
registered in humans, but in rodents these 
pathogens had not been found before that 

Figure 1. Etiological structure of human leptospirosis incidence in Ternopil region (annual percentage fraction of 
pathogens, 1980-2015, %).

 

1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 2011 2013 

L. grippotyphosa L. icterohaemorrhagiae L. hebdomadis L. canicola L. pomona 

N. A. Vasylieva, Yu. A. Kravchuk



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time. In 2010 one case of leptospirosis in hu-
mans caused by L. australis was registered. 
According to the epidemiological anamnesis 
the source of infection has not been estab-
lished. The contamination possibly happened 
at other area.

The animals can be the source of lepto-
spirosis infection too. The vaccination process, 
natural infection or animal disease might cause 
their serological positivity. The vaccine do not 
contain L. kabura, (L. hebdomadis), L. bratislava, 
which are often detected in animals. 

Every year the carriers of leptospirosis and 
disease incidence in farm animals were regis-
tered at private and collective farms of Ternopil 
region which ended up with animal death and 
abortion; from 1983 epizootic diseases were 
rare, clinically apparent forms of leptospirosis 
were not registered, however, sufficiently high 
titers (1: 400) of antibodies were defined, which 
evidenced about carrying or subclinical form of 
the disease in animals and we should consider 
them as potential sources of leptospirosis for 
humans. It is possible that the animals’ infection 
happened after restocking from other farms 
and areas.

According to the recent researches, the du-
ration of leptospirosis carrying in cattle is up to 
6 months: in pigs − up to1 year; 10% of cattle 
and 30% of pigs are carriers for life, as well as 
rats and mice [4]. However, some authors 
believe that at most areas the domestic and 
farm animals are not very important for the 
epidemiology of leptospirosis because rats 
usually are revealed at these loci [5].

Etiological structure of animal leptospirosis 
is diverse and includes L. icterohaemorrhagiae, 
pomona, grippotyphosa, hebdomadis, polonica, 
canicola, kabura, tarassovi; L. bratislava was 
registered in 2007 (87.5% in pigs in 2008), often 
diagnostically significant titers of antibodies to 

two different serovars are defined at the same 
time (71,4–78,0% in cattle in 2003–2006).

Till 1983 only leptospira of Grippotyphosa 
and Icterohaemorrhagiae serogroups, someti-
mes of Hebdomadis, was detected; later 
antibo dies to other serovars were identified: 
Canicola in rats (2004), Kabura (2006) in 
different kinds of voles, except Grippotyphosa, 
also Icterohae morrhagiae, Pomona, Canicola, 
Hebdomadis; the expanding of pathogens and 
their further distribution in all kinds of 
examined mouse-like rodents took place. In 
2015 leptospira Polonica was identified in 
rodents for the first time.

The range of serologically identified patho-
gens was listed during the monitoring of 
humans, farm animals and mouse-like rodents 
(Table 1).

Due to this study and our previous re-
searches [6–8] we verify that leptospira serovars 
in farm animals cause the human diseases 
because these pathogens were not exuded by 
rodents in this region before. New leptospira 
serovars, which are carried mostly by farm 
animals and humans are infected through 
environment from them, in humans are usually 
registered in 3–5 years after they are exuded 
from animals. We also evidence the further 
spread of the new pathogen serovars at this 
area in all kinds of examined mouse-like 
rodents.

So, it was proved that farm animals and 
rodents are competing reservoirs of leptospirosis 
pathogens. To predict future epidemiological 
situation of leptospirosis in humans and to 
improve its diagnosis the monitoring of the 
population, infection and leptospira carriage 
among mouse-like rodents and farm animals 
and expanding of the panel of diagnostic 
leptospira strains including new pathogen 
variants in animals is necessary.

Table 1. Leptospirosis pathogens serologically identified in humans,  
farm animals and rodents (1972-2015). 

Rodents Farm animals Humans
L. icterohaemorrhagiae (1972) L. icterohaemorrhagiae (1972) L. icterohaemorrhagiae (1972)

L. grippotyphosa (1972) L. grippotyphosa (1972) L. grippotyphosa (1972)
L. hebdomadis (1983) L. hebdomadis (1981) L. hebdomadis (1981)

L. canicola (1982, 2004) L. canicola (1979) L. canicola (1982)
L. pomona (2008) L. pomona (1979) L. pomona (1982)
L. kаburа (2006) L. kаburа (2002) L. kаburа (2005)
L. polonica (2015) L. polonica (2002) L. polonica (2007)

L. tarassovi (2002)
L. bratislava (2007)

L. australis (2010)

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ISSN 2413-6077. IJMMR 2016 Vol. 2 Issue 1

Thus, the factors that contribute to the 
evolution of the epidemic process in leptospirosis 
are:

– biological changes of the natural reservoir – 
species composition of rodents, their number 
and contamination;

– expanding of new leptospira strains into 
endemic areas of farm animals, which cause 
human infection through environment and 
further spread among mouse-like rodents and 
pathogen establishment there.

Prevention: annual examination for lepto-
spirosis of breeding stock and animals pur-
chased for sale in other farms; sterilization of 
animal carriers; vaccination; diratisation; 
draining of wetlands could decrease (possibly 
avoid) the expanding of new leptospira strains 
into endemic areas and prevent the disease 
incidence in humans.

Conclusions
1. The development of additional reservoirs 

in animals, with circulating of other pathogen 
serovars among them, such as mouse-like 
rodents, which were previously absent in the 
main natural reservoir, cause the change of 
etiological structure in human leptospirosis at 
the endemic areas.

2. The range of human leptospirosis patho-
gens and its further spreading among all kinds 
of rodents increased during our research.

3. The results of detection of leptospirosis 
pathogens among the various contingents 
which were studied evidence that the farm 
animals and rodents are competing reservoirs 
that cause human infection through envi-
ronment.

References
1. Costa F, Hagan JE, Calcagno J et al. Global 

Morbidity and Mortality of Leptospirosis: A System-
atic Review. PLoS Negl Trop Dis 2015; 9 (9): 3898. 

2. Виноград НО, Кіріяк ОП, Мурзова ЛІ та ін. 
Еколого-епідеміологічні особливості лептоспірозу 
на Івано-Франківщині. Сучасні інфекції 2004; 1: 
60-65.

3. Кравчук ЮА, Васильєва НА. Епізоотолого-
епідеміологічні особливості лептоспірозу в Тер-
нопільській області. Анали Мечниківського інсти-
туту 2015; 2: 165-171.

4. Задорожна ВІ, Протас СВ, Гопко НВ та ін. 
Епізоотологічні та епідеміологічні аспекти лепто-
спірозу в Україні. К; 2014: 46.

5. Бернасовська ЄП, Кондратенко ВМ, Мель-

ницька ОВ. Проблема лептоспiрозу в Українi. 
Iнфекцiйнi хвороби 1996; 2: 37-39.

6. Васильєва НА, Буртняк ТВ, Блажкевич БВ, 
Грузина ЛО. Захворюваність людей на лептоспіроз 
та інфікованість патогенними лептоспірами гри-
зунів у Тернопільській області. Інфекційні хворо-
би 1995; 2: 22-25. 

7. Васильєва НА, Поліщук ЮА, Івахів ОЛ та ін. 
Епідеміологічні особливості лептоспірозу в захід-
ному регіоні України. Інфекційні хвороби 2008; 2: 
14-18.

8. Васильєва НА, Луцук ОС, Павлів ОВ. Ево-
люція епідемічного процесу лептоспірозу (за 
матеріалами Тернопільської області). Профілак-
тична медицина 2011; 2: 69-73.

Received: 2016-02-19

N. A. Vasylieva, Yu. A. Kravchuk