Efremova G.A.1, Bychkova E.I1.1, Movila A.A.2,
Jakovich M.M.1
TICKS
(ACARI: IXODIDAE) IN PSRER: ECOLOGY, GENETIC POLYMORPHISM AND EPIDEMIOLOGICAL-
EPIZOOTIC SIGNIFICANCE
1SSPA «
Scientific-practical center of the National Academy of Sciences of Belarus for
biological resource », Minsk, Republic of Belarus
2Institute of
Zoology, Academy of Sciences of Moldova, Chisinau, Republic of Moldova
Study of the effect of contamination on
biodiversity and abundance of the parasitic organisms to date remains one of
the most urgent problems of modern science. One of consequences of the radioactive
contamination area is to increase the infectiousness degree of animals by
bloodsucking arthropods, arising from a weakening of the immune system of the
host, which creates favorable conditions for the revival of dangerous viruses
for people and animal and circulating them in the existing foci of natural
disease. In the study of the parasitological and epidemiological situation in
the 5-, 10- and 15- kilometer zones of resettlement near Chernobyl among
radiation factor is very important to take into account an aggregate of other
elements that lead to the creation of conditions in the evacuation zone
(vegetable fluctuation processes, removal of anthropogenic pressure, etc.),
which specifically affect on the structure of parasite complexes .
Parasitological
studies carried out in the Chernobyl exclusion zone (Polessky State Radiation
Ecological Reserve, PSRER) starting from 1986, mainly devoted to various
aspects of the impact of new environmental conditions on the structure of
parasitic complexes and on the parasite organisms itself. The state and
dynamics of biodiversity and abundance of individual taxa of parasites [19, 29,
14 etc.], the basic aspects of formation of the parasite complexes in the
contaminated zone as a whole [17, 13, 28 etc.] and at their various owners,
including birds [9, 11.8, 7, 12, 30, 31 etc.), micromammals [15, 20, 14, 3 etc.]
and bloodsucking Diptera [25, 26 ,27] were studied. A number of papers devoted
to the identification of features of a dynamics of the animal parasite number in the contaminated area involves complex new factors [16,
6,18,19,4] and especially changes in the number of epidemic and epizootic dangerous
to people and animal parasites [17,18,20, 24, 34, 21etc.]. Virology tests of birds
in Belarus found 21 strains of viruses, of which 14 belong to the tick-borne
encephalitis, 1 - West Nile, 1 - West Nile TBE, 5 strains of unidentified
[24]. Noted, that birds wintering sites can bring West Nile virus, and others
[23]. In Belarus (including the Belarus Polesie) the antigemagglutinins to TBE
virus and West Nile virus [5, 9, 10, 32,33] were identified . In this
connection it is necessary to study the dynamics of the parasite fauna
and a number of birds and mammals, living in Polessky radiation-ecological
reserve, as large part of them can participate in the maintenance of existing
and emerging foci of vector-borne diseases.
The
material on the territory of the Polessky State Radiation and Ecological
Reserve (Hoiniki district Gomel region) were collect. The survey covered the
most biocenosis, which is typical to the southern part of the Republic of
Belarus: pine, oak, alder, meadows, drained marsh areas. Territory of the
evacuate settlements in the Chernobyl aloof zone were surveyed too. Animals for
parasitological examination were caught by conventional methods. Parasitic
arthropods, collected from small mammal and birds, in 70% alcohol were fixed.
For ascertain of the species diversity of ectoparasites the permanent
preparations were made. The stock-taking of number of the adult ticks on the
vegetation by the 20-minute territorial surveys "on flag" were
conducted.
The
analysis of the data, obtained from the study of species diversity and
abundance monitoring bloodsucking parasitic arthropods, showed that in this
area on small mammals 31 species of blood-sucking arthropods belonging to trombiculid,
gamasid ticks, lice and fleas were found. The most dangerous in the epidemic
aspect among the ectoparasites is the the Ixodes
ricinus complex - the main carriers of a number of vector-borne natural
focal diseases of humans and animals: tick-borne encephalitis, Lyme
borreliosis, piroplasmosis, Q fever and other [10, 22].
Ticks Ixodes ricinus (L., 1758) have
comparatively high number (index value of feeding on the small mammals reaches
8.2-12.5 individuals on animals). The highest rates of the number of this
species of ticks in the forest biocenosis (lder, oak, pine forests) were
detected. The registration of adult of the Ixodidae ticks on the flag showed
that the species composition in PSRER represented mainly overlooking Dermacentor reticulatus Fabricius,1794 (50-150 individual on taking
accounting). Ticks I. ricinus
sporadically in the territory of the evacuated villages and on the bank of the
lake were observed. Conducted audit tracking ticks in natural plant formations
(oak, alder, pine, birch) also showed a preferential distribution of D. reticulatus in the study area with a
maximum in the alder thicket sedge. Conducted audit tracking of the preimmature
stages of ticks on animals were shown that on the small mammals of surveyed
areas 4 species of ixodid ticks (Ixodes
trianguliceps Birula, 1895, I. ricinus,
I. persulcatus Schulze,1930 and D. reticulatus) are parasitized. Species
identification was carried out using a microscope as well as molecular genetic methods [1,2, 36].
Among tick
the species I. ricinus is the most dangerous in the epidemic aspect. He has the
highest number (index value of feeding the small mammals reaches 12.5
individuals on animals). In 1995-96 the second, in a very dangerous epidemic aspect
ixodid species - I. persulcatus - vector East Siberian
strain of tick-borne encephalitis (TBE) in small quantities (index value of
feeding on the small mammals reaches 0 ,2 - 0, 7 individuals) were recorded.
Maybe it was random drift by migrating
species animals or birds, but environmental conditions for the existence of
this tick species in PSRER are available. The presence this ticks on the
territory of reserve need the constant monitoring and control of
parasitological situation. The number
three of ixodid species is D.
reticulatus. On the small mammals his number is low. It should be noted
that this is the widespread species: from 80% to 100% among ixodid
accounts the share of this species in the calculation number of ticks in the
southern regions of the country. This tick species dominated in numbers on the territory PSRER too. This ticks feed
on many species of large and small mammals (wild boar, elk, deer, wolves,
horses, murine rodents), and its number amount to several hundred ticks on one
big animal. Thus species D. reticulatus
is the dominant on under consideration territory and the risk of natural focal
diseases carried by this type of tick rather high. Especially because on this
area from ticks D. reticulatus the
antigen-borne encephalitis virus was isolated [24]. Detection the encephalitis
virus antigen in ticks on the territory PSRER is evidence of maintaining
in reserve the natural focus of this
disease, which may present a potential risk to spread the infection outside
from the evacuation zone by transferring wild birds and animals.
Long-term
monitoring of number of the parasitic organisms on a territory contaminated by
radioactive nuclides (effort of 1986-1999 years) showed that in the Chernobyl
evacuation zone a tension of parasitological situation during 10 years were increased.
This applies to almost all groups of parasites: protozoa, endoparasites (helminthes),
ectoparasites of bird and small mammals, inhabitants of their nests. A similar
trend is characteristic to population number of free-living ticks. At the same
time it is need to noted that this situation is determined not so much a change
of the radiation situation in the study area but by secondary environmental
causes: particularly the removal of anthropogenic pressure as well as the
succession plant process, expressed
mainly in the bushing previously existing farmland and drainage systems. It is
significant the higher number of ticks in the evacuation zone compared with the
adjacent territories. Thus, in the period of the maximum number of ticks on
vegetation (in the middle of April) in the Chernobyl zone recorded an average
of 89.3 individual on calculation in
comparison with the neighboring territories - Mozyr, Loew, Lelchitsy - no more
than 3-5 individual on censuring. In accordance with the modern attempt to
describe the abundance of tick species in the Chernobyl exclusion zone (spring
2010) the species D. reticulatus was
absolutely the most abundant species, both on animals and free-living in the
environment [35].
Molecular genetic variability of 12S rRNA gene on the
basis of partial primary sequence, and in silico predicted secondary structures
among D. reticulatus ticks was
studied in the Chernobyl Nuclear Power Plant Exclusion Zone. A total of 20, 20,
and 25 ethanol-preserved specimens previously collected at 3 sites with 0.76,
1.91, and 4.5 mSv/hr ionising radiation background were examined. The primary
sequence analysis generated 4 haplotypes defined by 3 polymorphic sites. The
most common haplotype 1 was found in all 3 locations, representing 86.2% of all
sampled individuals. Haplotype 4 (10.8%) was detected at the 1.91 and 4.50 mSv/hr
sites. The unique haplotypes 2 (1.5%) and 3 (1.5%) were detected only at the
1.91 and 4.50 mSv/hr sites, respectively. The haplotype diversity, nucleotide
diversity, and pairwise nucleotide differences for 2 tick populations at the
1.90 and 4.50 mSv/hr sites were 0.279, 0.00085, 0.289, and 0.397, 0.00122, 0.
413 respectively. No polymorphism was detected in ticks collected at the 0.76
mSv/hr site. The primary sequences of 12S rRNA were folded into the secondary
structures, and the free energy of haplotypes was calculated. The free energy
at 37 C (ΔG) of the nonmutant haplotype 1 and the mutant haplotypes 2, 3 and 4
were -45.79, -44.17, -39.56 and -45.79 kcal/mol, respectively. Considering the
correlation between structural profile similarity of 12S rRNA and point
mutations, haplotypes 1 and 4 have similar secondary structure profiles and
have received 0.999219 similarity score in the cluster tree. The unique
haplotypes 2 and 3 have differences in the secondary structure in comparison
with the haplotypes 1 and 4, and the similarity scores were 0.914747 and
0.169431, respectively. Further studies using more genetic markers are
warranted to ascertain the genetic variability and population genetic structure
within D. reticulatus tick
populations in the Chernobyl Nuclear Power Plant Exclusion Zone [36].From the premises
the further investigations on parasitological situation in the zone of
alienation, which has revealed a variety of tick-borne pathogens in the area,
and the number and diversity of their carriers - epidemic and epizootic
dangerous species of parasitic organisms and animals, on which they feed, that
in the tenth anniversary after the accident had a constant tendency to
increase. The necessity to continue the fundamental investigation of these
studies are connect with the fact that in a case of the uncontrolled
development of the parasite may be a source of spread of viral and bacterial
infections outside the evacuation zone.
REFERENCES
1. Aksenova
E.A., Lukhanina N.V., Efremova G.A., Babushnikova E.P.,
Jakovich M.M.,Yashkova S.E., Davydenko O.G., Bychkova E.I. Development of
effective DNA markers for species identification of ticks on the territory of
Belarus / / Epizootology. Immunology. Pharmacology. Sanitation. . 2007a.№ 2. P.
20-24 (In Russian).
2. Aksenova E.A, Efremova G.A., Lukhanina
N.V., Babushnikova E.P., Jakovich M.M. Yashkova S.E. Species identification of
ticks using DNA markers / / International scientific conference "Molecular
diagnosis of infectious diseases." Minsk, May 17-18, 2007b. P. 193-195 (in Russian).
3. Balagina
N.S Polessky Radiation Ecological Reserve as a testing ground for parasitological
studies of micromammal parasitocenoses / / "10 years Polesye State
Radiation Ecological Reserve." Minsk.
1998. P.194-198 (in Russian).
4. Bychkova E.I, Anisimova E.I.,
Odintsova T.M. Basic laws of dynamics of the most dangerous helminth invasions
of vertebrates in the area of the Chernobyl accident / / Ten
years after the Chernobyl disaster (the scientific aspects of the problem)
Proceedings of the International Conference. Minsk. 1996. P. 52 (in Russian).
5. Voinov
I.N., Samoilova T.I., Grigoriev A.I., Gembitsky A.S., Efremova G.A., Nazarov V.I. Coastal colony of swallows
(Riparia riparia L.) as micro foci of
TBE / / "Ecology of viruses. Proceedings of the IX Symposium (October,
1975). Dushanbe: Donish, 1975. P.161 (in Russian).
6. Efremova G.A., Bychkova E.I.,
Gembitsky A.S., Zuyenok S.V. Changing of bird parasite complexes under the influence of the radionuclide
contamination in Belarus / / I All-Union Congress on radiobiology. Moscow,
21-27 August 1989. Pushchino, 1989. P.446-447
(in Russian).
7. Efremova
G.A. Parasite of birds and their nests in the area of the
Chernobyl nuclear power plant accident / / Radiobiological Congress. Kiev,
Sept. 20-25. 1993.Abstracts. Part 1. Pushchino. 1993. P.352-353 (in Russian).
8. Efremova G.A., Bychkova E.I. Bird parasite
cenosis in the accident area of
the Chernobyl nuclear power plant / / Actual problems of
medicine, veterinary medicine and parasitology. Proceedings of the International
Scientific Conference. Vitebsk, Sept. 23-24. 1993. Vitebsk. 1993. P.120 (in Russian).
9. Efremova
G.A. The role of the inhabitants of the swallows' nests on the reservation
agents of natural focal infections / / Abstracts of the XII All-Union
conference on natural foci illnesses. Novosibirsk. 10-12 October1989.
Novosibirsk, 1989.P.79-80 (in Russian).
10. Efremova
G.A., Mishaeva N.P. Azarova I.A. The main reservoirs and vectors of pathogens natural
focus infections: a new look at the problem / / Problems of natural foci. Proceedings
of Parasitological Society meeting at RAS. St. Petersburg, June 8, 1999. St.
Petersburg, 1999. P.71-104 (in
Russian).
11. Efremova
G.A., Chikilevskaya I.V., Balagina N.S. The structure of the nest parasite cenosis
of birds and small mammals in the
evacuation zone near Chernobyl / / Ten
years after the Chernobyl disaster (scientific aspects of the problem.)
Proceedings of International Scientific Conference. 28-29 February 1996. Minsk, 1996.
P. 161 (in Russian).
12. Efremova
G.A. Radioecological monitoring of nest parasite cenosis of birds in Polessky reserve / / 10 years
Polessky State Radiation Ecological Reserve. Minsk. 1998. P. 214-220 (in
Russian).
13. Kireenko
K.M., Labetskaya A.G., Anisimova, E.I., Chikilevskaya I.V., Baidakova I.V.,
Kononova I.M., Balagina N.S. Dynamics of micromamalia parasite complexes in the
area of Chernobyl accident. Deposited
in the UNP NPETS "Veras-Eco" 18.01.94, № 384. 14 s. (In Russian).
14. Kireenko
K.M., Labetskaya A.G., Bychkova E.I., Balagina N.S. etc. The current state of
of micromamalia parasite complexes in Polesskoe State Radiation Ecological
Reserve / 10 years Polessky State Radiation Ecological Reserve. Minsk,
1998. P. 183-194 (in Russian).
15. Labetskaya
A.G., Balagina N.S. Parasite of small mammals in the area of
radioactive contamination of the Chernobyl nuclear power plant
and the neighboring territories / / Abstracts I radiobiological Union Congress.
Moscow. 1989. P. 470 (in Russian).
16.Labetskaya
A.G., Bychkova E.I., Kireenko K.M., Balagina N.S. Habitat distribution of
parasitic organisms in the contaminated territory by radionuclide / /
Proceedings of the All-Union Conference "Radiobiological consequences of
the Chernobyl accident. Minsk, 1991. P.71 (in Russian).
17. Labetskaya
A.G., Kireenko K.M., Baidakova I.V. Number of epidemiologically dangerous small
mammals ectoparasites in Chernobyl zone and near by areas // Proceedings of the zoological VII
Conference "Problems of the study, conservation and use of biological
diversity of the animal world." Minsk, 1994. P. 212-214 (in Russian).
18. Labetskaya
A.G., Kireenko K.M., Baidakova I.V., Tishechkina I.M. The influence of the
succession process to change the parasitological situation in the zone of
Chernobyl accident / / Proceedings of the International Conference
"Chernobyl 10 years." Minsk,
1996. P.165 (in Russian).
19. Labetskaya
A.G., Kireenko K.M., Baidakova I.V., Tishechkina I.M. Abundance and
biodiversity of parasites micromammalia in the evacuation of the Chernobyl
nuclear power plant / / Parasitology.
1997. V.34, (5). P.391-396 (in Russian).
20. Labetskaya
A.G, Kireenko K.M., Baidakova I.V. The spread of vectors and infectious agents
in areas contaminated with radionuclides / / Proceedings of the
Proceedings of the
International Conference "Fundamental and applied aspects of
radiobiology." Minsk, 1998. P.114 (in Russian).
21. Labetskaya
A.G., Bychkova E.A, Efremova G.A, Tereshkina N.V. Balagina N.S., Yakovich M.M.
Medical and social aspects of the consequences of the man-made disaster in Polessky State Radiation
Ecological Reserve / / III International scientific-practical conference
"Emergency situations: prevention and elimination " dedicated to the
150th anniversary of the fire service in the Republic of Belarus. Minsk, 23-25
July 2003. Proceeding of conference. Minsk: Ed. BSU Center, 2003.
Part 2. P. 187-188 (in Russian).
22. Savitsky
B.P., EfremovaG.A, Karpuk L.I. Pasture species of ticks in Belarus and the
results of study of their role in the pathology of human and domestic animal /
/ Ecology and wildlife. The International Scientific Journal. № 1. 2008.
P.11-22 (in Russian).
23. Samoylova
T.I., Voinov I.N., Grigoriev A.I., Gembitsky A.S., Leshkov S.T. New for Belarus
arbovirus associated with birds / / Ecology of viruses. Proceedings of the IX
Symposium (October, 1975). Donish: Dushanbe, 1975. P. 163-165 (in Russian).
24. Samoylova
T.I., Labetskaya A.G. , Bolshunova L.A., Kireenko K.M., Titova O.V., Lahvinets
N.G., Grachev A.G. The study of the spread of encephalitis and HFRS viruses in
the zone of the Chernobyl nuclear power plant / / International conference
"Zooanthropozoonosis diseaseas, prevention and control." Grodno,
1997. P.52-53 (in Russian).
25. Tereshkina
N.V., Trukhan M.N., Kaplich V.M. State and dynamics of faunal assemblages of bloodsucking
Diptera in areas with varying degrees of radionuclide contamination / /
Deposited in the UNP SPC "Veras" and from the NSA 03/17/1994
15-15. № 412. 18 s. (In Russian).
26. Tereshkina
N.V., Trukhan M.N., Kaplich V.M., Jakovich M.M. State of bloodsucking Diptera insect complexes - vectors of vector-borne diseases in area of
the radionuclide contamination of Chernobyl PP/ / Proceedings of
the International Conference "10 years after the Chernobyl disaster"
(February 26-28, 1996, Minsk). Minsk.1996. P.34-36 (in Russian).
27. Truhan
M.N., Tereshkina N.V., Kaplich V.M. Bloodsucking Diptera complexes in the
contaminated zone of Chernobyl PP / / Abstracts of the All-Union Conference
"Radiobiological consequences of the Chernobyl accident." Minsk, 1991
(in Russian).
28. Chikilevskaya I.V., Labetskaya A.G.
Evaluation of parasitological situation in the Chernobyl accident zone/ /
Proceedings of the VII zoological Conference "Problems of the study,
conservation and use of biological diversity of the animal world." Minsk,
1994. P.231-232 (in Russian).
29. Bychkova E. I. Special features of
formation of fauna of helminths in urban and wild mallard Anas platyrhynchos L. population // “ Ecology of bird – parasite interaction”. A Special Symposium. Vilnius,
1998. P.19.
30. Efremova G.A. The influence of radionuclide pollution of Belarus on the
bird’s parasitocenosis structure// 2-nd International conference “Radiobiological consequnces of nuclear accident:
Abstracts.Part2.24-26 October 1994. Moscow,
1994. P. 52.
31. Efremova G.A. State of the bird’s parasitocenosis
in the zone of Chernobyl nuclear accident in Belarus// Abstracts: VIII European
Multicolloquium of Parasitology. 10-14 September 2000, Poznan, Poland/ Acta
parasitologica. 2000. Vol. 45, No3. P.226 – 227
32. Efremova G.A., Gembitsky A.S. Parasitic arthropods
of birds and their role in maintenance of natural foci of arboviruses diseases
in Belarus// Bulletin of the Scandinavian Society for Parasitology (SSP).
Vol.8. N2. 1998. P.60
33. Efremova G.A., Gembitsky A.S. Parasitic arthropods
of birds and their role in maintenance
of natural foci of arbovirus diseases in Belarus// Ekologija, 1999. N4. P. 55-60
34. Labetskaya A.G. Mapping of the density of Ixodoidea in Belarus// Parasitology
International .1998. Vol.47. Suppl. P.388.
35. Movila
A, Deriabina T, Morozov A, Sitnicova N, Toderas I, Uspenskaia I, Alekhnovich A.
Abundance of adult ticks (Acari: Ixodidae) in the Chernobyl nuclear power plant
exclusion zone. / / Journal of Parasitology, Vol. 98. No. 4., 2012a, P.
883-884.
36. Movila
A., Morozov A., Sitnicova N. Genetic polymorphism of 12S rRNA gene among Dermacentor reticulates Fabricius ticks
in the Chernobyl nuclear power plant exclusion zone // Journal of Parasitology,
2012b. doi: http://dx.doi.org/10.1645/GE-3225.1