Morphological and physiological, biological and epidemiological features of acariana of the genus Ixodes (Latreille, 1795) – human ectoparasites in biogeocenoses of Ternopil region
MORFOLOGICZNE, FIZJOLOGICZNE, BIOLOGICZNE ORAZ EPIDEMIOLOGICZNE CECHY ROZTOCZY Z RZĘDU KLESZCZY (LATREILLE, 1795) – LUDZKICH EKTOPASOŻYTÓW W BIOGEOCENOZIE W OBWODZIE TARNOPOLSKIM
Larysa Ya. Fedoniuk1, Stepan S. Podobivskyi1, Alexandr M. Kamyshnyi2, Аnna S. Saturska1, Vira О. Khavtur1,
Оlga М. Marchuk1, Оksana М. Zahrychuk1, Оlga B. Furka1, Valentyna М. Cherniashova1
1STATE HIGHER EDUCATIONAL ESTABLISHMENT IVAN HORBACHEVSKY TERNOPIL STATE MEDICAL UNIVERSITY OF MINISTRY OF PUBLIC HEALTH OF UKRAINE, TERNOPIL, UKRAINE
2Zaporizhzhia State Medical University, Zaporizhzhia, Ukraine
Introduction: Ixodine are an integral part of many biotopes, in particular rarefied deciduous and mixed forests, gardens, parks, squares, semi-steppe and steppe areas, etc. Over the past decade, the role of ticks has increased in the transfer of pathogens of many diseases of animals and humans. In particular, these are tick borelliosis, anaplasmosis, erlichiosis, babesiosis, and etc. An important element of the study of ticks is the study of their morphology, physiology, biology, medical and sanitary significance.
The aim: Investigation of morphological and physiological features of various life stages of ticks during the feeding period, studying the epidemiological state of acariana in different seasons.
Materials and methods: The main materials and tools used to catch, keep and identify the ticks were tweezers, lenses, microscopic needles, white cloth for the «flag», alcohol 70%, test tubes. The study was carried out using optical and electronic system SEO-IMAGLAB. Investigation of epidemiological state was carried out using the polymerase chain reaction (PCR) using amplifier method “ROTOR Gene -6000” in real time.
Results: As a result of the analysis of morphological parameters, certain regularities in the ratio of total body length to the width of the abdomen were found at different stages of saturation. From the investigated acariana in 2017 to detect infectious pathogens, 46 females (39%), 56 nymphs (32%), 1 larvae (33.3%) were investigated. 2 undetected acariana were carriers of 3 types of pathogens infectious diseases: Borrelia Burgdorferi senso lato (66 cases), Anaplasma phagocytophilum (30 cases) and Borrelia Miyamotoi (6 cases). According to the results of 2018, the number of carriers of the infectious agents was 158 (33.2%), which of them were females 58 (33.7%), males 2 (40%), nymphs 86 (32.5%), larvae 2 (10.5%).
Conclusions: Proceeding from the analysis of the infection frequency of Ixodes ricinus carriers of infectious diseases, it was found out the increase in the number of females and nymphs of borrels carriers, from May to July with an average temperature increase of 18-230С to 25-270С and subsequently a decrease in the frequency of their infection from August to October when the temperature drops to 20-150С.
Key words: Ixodes, Ixodes Latr., Dermacentor Fabr., Ixodes ricinus, Dermacentor reticulatus, Borelli, Anaplasm
Wiad Lek 2019, 72, 2, 114-228
Among the large variety of arthropods of invertebrates, a large number of them have a sanitarian and medical significance for humans [1, 2]. One of these groups is a subclass of ticks (Acarina), which includes more than 1600 species in the world’s fauna [3, 4, 5]. On the territory of Ukraine among the acarina, which have sanitarian and medical significance, the most representative family (Ixodidae), found in various natural and artificial habitats, including urban areas, is the most represented. [6, 7] Their number, population density, sex ratio and even contamination with various pathogens of infectious diseases depends on the circulation of pathogens in the range of potential ticks at seasonal conditions of the environment .
In general, ticks are highly specialized hematophages and carriers of many transmissible diseases of humans and animals [9, 10]. Y. S. Balashov and Y. M. Yemchuk [11, 12] in their theses indicate that ticks of Ixodes, Dermacentor, Ripiciphalus, Hyalomma are capable to transfer more than 10 transmissive diseases to animals and humans: boreliosis, pyroplasmosis, anaplasmosis, babesiosis, listeriosis , brucellosis and others.
During the last 15 years, the number of infection cases of people with various Borelians caused Lyme disease and granulocytic anaplasmosis has considerably increased.
The deterioration of the acarological situation in Ukraine, the increase of contact between man and domestic animals with ticks, the existence of natural cells of tick infections, cause increased interest in the study of tick-borne monofilaments and the ways of their prevention, which is relevant today.
To study the ecological, biological, morphological and physiological features of the most common types of Ixodes – carriers of transmissible diseases in Western Ukraine and to establish patterns of correlation of morphological indices during feeding. To set a list of pathogens and the degree of infection of them, acarina that were on people and were taken off from children in a traumatology center in Ternopil.
Materials and methods
The main morphometric parameters studied in ticks of Ixodes ricinus were: total body length, abdominal width, length gnatosome and scutum (shield).
798 ticks of Ixodes ricinus were investigated. All ticks of the first type were found mainly in the city of Ternopil and Ternopil region, as well as some ticks were brought from Lviv, Ivano-Frankivsk and Rivne regions. The main materials and tools used to catch, keep and identify the ticks tweezers, lenses,
microscopic needles, white cloth for the «flag», alcohol 70%, test tubes, optoelectronic system SEO – IMAGLAB.
To identify ticks, we used the definition tables given in the monographs of domestic and foreign scientists [13, 14].
The determination of the pathogens that the extracted ticks transmitted were performed using the polymerase chain reaction (PCR) method in real time by preparing a mash suspension, isolating the DNA itself and carrying out further amplification using the “ROTORGene -6000” amplifier in real time.
Ticks were taken off from people with tweezers or threads by screwing head, neck, limbs, and abdomen from the skin.
Results and discussion
Morphological examination of ticks was carried out in the direction of setting morphological indices of individual parts of the body (total body length, length of gnatosome and skutum, abdominal width) and identification of possible patterns in changing these parameters depending on the stages of saturation at different stages of life of ticks.
The morphology peculiarities of 124 females and 198 nymphs of Ixodes ricinus were studied.
We have accepted the conditional blood stages of various life forms of ticks, which is reflected on the lower axis of the diagrams: 1 – unsaturated; 2 – partially saturated; 3 – saturated; 4 – strongly saturated; 5 – the most saturated.
As a result of the analysis of morphological indices of individuals of Ixodes ricinus, we found that females total length of their body and the width of the abdomen is greatest in the stage of maximum saturation and is 8.7 mm and 6.16 mm respectively, and the smallest – in the first stage, where the total length the body of the female is 3.01 mm, and the width of the abdomen – 1.69 mm (Fig. 1). When conducting a correlation analysis of blood saturation of life forms of female ticks, the following correlation is observed: 1: 0.56; 1: 0.59; 1: 0.53; 1: 0.6; 1: 0.7. Consequently, in females with an increase in the degree of saturation increases not only the length of the abdomen, but also its width.
As a result of the study, it was found that there are separate patterns in the ratio of total body length to the width of the abdomen at different stages of saturation in the nymph (Fig. 2).
Based on the obtained results, we see that the width of the abdomen in the nymph increases during the five stages of saturation very slowly (from 0.7 mm to 1.61 mm), but the body length increases (from 1.24 mm to 2.76 mm). The correlation is as follows: 1: 0.56; 1: 0.56; 1: 0.58; 1: 0.6; 1: 0.58.
Indicators on the length of the gnatosoma and the length of the shield both, females and nymphs of Ixodes ricinus, do not have significant oscillations in the parameters and is an average of 0.92 ± 0.7 mm (gnatosome length of females), 0.39 ± 0, 3 mm (shield length of females), 0.50 ± 0.4 mm (gnatosome length of nymph), 1.13 ± 0.9 mm (shield length of nymph).
From April to October 2018 morphological indices of the body of larvae were investigated depending on their saturation with human blood. The results are presented in Fig. 3.
As it can be seen from the diagram, the increase in the blood volume of the larvae is mainly due to an increase in the length of the abdomen (increase in 2 times) but not in width (increase only in 1,3 times).
During the period from May to October 2017, 118 females, 174 nymphs and 3 larvae of Ixodes ricinus were tested in Ivan Horbachevsky Ternopil State Medical University of Ministry of Public Health of Ukraine, in order to detect pathogens of infectious diseases [7, 11].
From 08.05.17 to 07.07.17, 179 ticks were examined, 117 nymphs (infected with borrels 36 or 31%), 51 females (17 or 33% infected with borrels) and 11 specimens were not identified, as there were only their individual fragments. As victims, predominantly (89%) were children. The studies were conducted to detect DNA of the pathogens of boreliosis and anaplasmosis. According to the results of amplification, borelles and anaplasms were found in different life stages of the species Ixodes ricinus. In particular, Borrelia Burgdorferi senso lato was detected in 37 cases, including in adult ticks – 11, in nymphs – 25, the stage is not defined but only in one case. Anaplasma phagocytophilum was detected in 15 cases, including adult ticks – 5, in nymphs – 9, undefined stages – 1. Borrelia Miyamotoi was identified in 5 cases, including 1 adult ticks and 4 cases of nymphs. The last one was first detected in Ukraine in 2002 amonth Ixod mites .
From 10.07 to 18.07.2017, 18 female ticks of the species Ixodes ricinus were examined, the carriers of pathogens were 13, which is equal to 72% (Borrelia Burgdorferi – 9, Anaplasma phagocytophilum-4). From infected females, three were both carriers of Borrelia Burgdorferi and Anaplasma phagocytophilum. During this period, 27 nymphs were also examined, 10 were carriers of pathogens (37%), (1 – Borrelia Burgdorferi and 9 – Anaplasma phagocytophilum). The detected larva was not a carrier of Borelli.
From 11.09 to 18.10.2017, 81 ticks of Ixodes ricinus (50 females, 1 larva, 30 nymphs) were examined. All ticks of Dermacentor reticulatus were not carriers of any of the pathogens. Of all the female acarina of Ixodes ricinus, the carriers of the pathogens were only 16, which is equal to 32% (14 – Borrelia Burgdorferi, 1 – Anaplasma phagocytophilum, 1 – Borrelia Miyamotoi). Of the 30 nymphs of ticks, carriers were 8 (27%), 3 – Borrelia Burgdorferi, 3 – Anaplasma phagocytophilum, 1 – Borrelia Miyamotoi. It should be noted that in the period from 2.10 to 18.10.2017, out of 22 examined female ticks of Ixodes ricinus, only 5 were carriers of Borrelia Burgdorferi (22%), and only 1 was infected with Borrelia Burgdorferi (14%) of 7 nymphs. Two larvae were taken off from the body of children infected with ticks and only one of them was the carrier of Anaplasma phagocytophilum.
During the period from April to October 2018 a polymerase chain reaction was conducted to detect pathogens of the three above-mentioned infectious diseases among Ixodes ricinus species in females, males, nymphs and larvae was carried out. Based on these studies, we see that of 68 infected female carriers with Borrelia Burgdorferi were 39 (57.4%), Anaplasma phagocytophilum – 22 (32.3%), together with Borrelia Burgdorferi and Anaplasma phagocytophilum, 7 (10.2%) females.
Among 5 infected males, there were only 2 (40%) carriers of Borrelia Burgdorferi.
Among 85 infected nymphs there were 35 (41.1%) carriers with Borrelia Burgdorferi, Anaplasma phagocytophilum 43 (50.5%), Borrelia Burgdorferi and Anaplasma phagocytophilum had 7 (8.2%) and Borrelia Burgdorferi and Borrelia Miyamotoi at the same time (1 (1.1%).
Among 19 examined larvae, there were two carriers of pathogens (10%), one of them had Borrelia Burgdorferi and Anaplasma phagocytophilum (50%), and another carried Borrelia Burgdorferi and Borrelia Miyamotoi (50%) at the same time.
As we see from the general results of females, nymphs and larvae of Ixodes ricinus take an active part in the transfer of all three pathogens of infectious diseases. Including a complex carrying, that is the simultaneous transfer of pathogens of two diseases.
Taking into consideration the dynamics of the frequency of infection with ticks of Ixodes ricinus, we observed an increase the number of females and nymphs that are carriers of pathogens in the period of May-July, and then, decrease the frequency of their infection in August-October. Obviously, the main cause of these fluctuations is the temperature regime, which changes in the spring-summer-autumn periods. Thus, the average temperature in May-June was 18-230С, in July-August – 25-270С, in September-October – 20-150С. At a temperature of 10-120С, the number of patients affected by ticks decreased. As a result of studies on the influence of seasonal changes on the degree of infection with ticks of Ixodes ricinus by pathogens of infectious diseases, it’s direct dependence on the temperature regime: at a temperature of about 18-150С, the degree of infection in the nymph is 14%, and in females – 22%, while at 25 -280С in the nymph this figure is 37%, and in females – 72%.
1. Between the total length of the body and the width of the abdomen, at different stages of saturation, a correlation ratio of 1: 0.5 – 1: 0.6 is observed, in contrast to the lengths of the gnatosome and the length of the skutum (shield), where there is no correlation corresponding to the norms of the disruptive selection.
2. In ticks of Ixodes ricinus, human ectoparasites are not only adult ticks, but also nymphs and even larvae (the ratio of taken off nymphs and adult females from children is 2: 1).
3. Females of ticks are more carriers of Borrelia Burgdorferi, and the nymphs are carriers of Anaplasma phagocytophilum and Borrelia Miyamotoi. Larvae can be human ectoparasites and tolerate all three pathogens of infectious diseases. Including a complex carrying, that is the simultaneous transfer of pathogens of the two diseases.
4. Among the males, the carriers were found of Borrelia Burgdorferi senso lato spirochete. At the present moment, carriers of other pathogens have not been investigated by us.
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According to the order of the Authorship.
Conflict of interest:
The Authors declare no conflict of interest.
Medical Biology of the I. Horbachevsky State Medical University
Valova street 9, 46000, Ternopil, Ukraine
Fig. 1. Indices of the body structure of females acarina Ixodes ricinus
Fig. 2. Morphological indices of nymph of Ixodes ricinus
Fig. 3. Dependence of the morphological indices of the larvae body and their blood saturation