Larval Forms Research Articles

HELMINTH FAUNA OF MUSTELIDS (NEOVISON VISON, LUTRA LUTRA, MARTES MARTES, MUSTELA PUTORIUS, MELES MELES) AT CENTER OF EUROPEAN PART OF RUSSIA (Preliminary results)

Helminthological autopsies of Mustelids from various districts of Pskov, Тver and Smolensk region were carried out. To determine the prevalence rates of the infestation, an extensive invasion index was used. According to the results of helminthological autopsies, a list of detected helminthes is given. For the first time on the study area, 14 species of helminthes were recorded in studied Mustelids. Two of the found species of helminthes parasitize in Mustelids in larval form. The maximum variety of species is observed among the Nematoda class. The data on the number of detected helminth species in Mustelids in certain districts of the Tver, Pskov and Smolensk regions, as well as indicators of the frequency of helminthes were given. The maximum number of helminth species is recorded in Mustelids in the Novosokolnichesky district of the Pskov region. Extensiveness of invasion of all studied species of Mustelids, excluding otter, is 100%. According to the indicators of extensiveness of invasion in the studied Mustelids, Isthmiophora melis, Capillaria mucronata, Capillaria putorii, Filaroides martis are prevalent. The maximum number of species of parasitic worms is recorded in pine marten. The research results indicate the dominant influence of the trophic factor in the formation of the helminth fauna of martens that inhabit the study areas.

Massive infection of a song thrush by Mesocestoides sp. (Cestoda) tetrathyridia that genetically match acephalic metacestodes causing lethal peritoneal larval cestodiasis in domesticated mammals

BackgroundPeritoneal larval cestodiasis induced by Mesocestoides Vaillant, 1863 (Cyclophyllidea: Mesocestoididae) is a common cause of severe infections in domestic dogs and cats, reported also from other mammals and less frequently from birds. However, there is a limited knowledge on the taxonomy of causative agents of this disease.ResultsIn the present study, we investigated a massive, likely lethal, infection of a song thrush Turdus philomelos (Passeriformes: Turdidae) by Mesocestoides sp. tetrathyridia. We performed combined morphological and phylogenetic analysis of the tetrathyridia and compared them with the materials obtained previously from other birds and mammals. The metrical data fitted within the wide range reported by previous authors but confirmed the limited value of morphological data for species identification of tetrathyridia of Mesocestoides spp. The molecular analyses suggested that the isolates represented an unidentified Mesocestoides sp. that was previously repeatedly isolated and sequenced in larval and adult forms from domestic dogs and cats in Europe, the Middle East and North Africa. In contrast to the present study, which found encysted tetrathyridia, four of the five previous studies that identified the same species described infections by acephalic metacestodes only.ConclusionsThe tetrathyridia of the examined Mesocestoides sp. are described in the present study for the first time. However, the possible match with the species that were previously reported to infect birds remains uncertain. The phylogenetic analyses also suggested the rejection of two cases that were previously identified as Mesocestoides corti as they were likely caused by the same species as in the presently reported infection case. The newly provided DNA sequences should allow the assignment to species in the future, when adults of the genus Mesocestoides are more thoroughly sequenced.

FISH INVASION BY OPISTHORCHID FLUKES IN THE WATERPOTS OF THE CITY OF NOVOSIBIRSK

The article presents data on the contamination of carp family fish with opisthorchid metacercariae and on the basis of this study, local foci of opisthorchidosis in reservoirs within the city of Novosibirsk were identified. Fishes for research were caught in the Nizhnyaya Yeltsovka and Inya rivers within the city of Novosibirsk. Fish studies were carried out by the compressor method. A total of 121 specimens of five species were investigated: ide, roach, dace, bream, verkhovka. Three types of opisthorchid metacercaria are found: Opisthorchis felineus, Metorchis bilis, and M. xanthosomus. The first two species have an epidemic significance, the latter – epizootic one. To assess the infection of fish, indicators of extensiveness and intensity of invasion, as well as an abundance index, were used.The results of studies showed that the level of infection of carp fish with larval forms of opisthorchids is 48.8% in total, while infection with metacercariae is: O. felineus 19.8%, M. bilis is 27.3% and M. hantomomus is 4.1%. In Lower Yeltsovka, the infection rate was 45.8%, in Ina – 55.3%. Earlier, our studies in the Lower Yeltsovka river detected mollusks-bitiniids, the first intermediate hosts of opisthorchids infected with their partins. Since the presence of the first and second intermediate, as well as definitive (human) hosts, is recorded at this point, the presence of a local focus in Lower Eletsovka can be considered indisputable. In Ina, the presence of a local focus is highly likely; for its final proof, it is necessary to detect opisthorchid-infected mollusks of this parthenites of Bithyniidae family.

STUDY OF DISTRIBUTION SPARGANOSIS IN BIOLOGICAL SYSTEMS THE CENTRAL CHERNOZEM REGION OF THE RUSSIAN FEDERATION

he distribution of sparganosis in the biosystems of the Central Chernozem region of the Russian Federation has been studied, material on the ecology, biology and distribution of sparganum has been collected in various territorial units of the CCR, infection of wild animals with both mature and larval forms Spirometra erinaceieuropaei (Rudolphi, 1819) has been determined. For the first time procercoids, spirometers were found in the intermediate host Ciclops strenuus(Fischer, 1851).The strongest water semination of surface water bodies was observed in the Rylsky district (Kursk region). 15 out of 133 (12.7%) studied water samples contained eggs of sparganum. We suggest that the appearance of sparganum eggs in surface water bodies is caused by washing off of sparganum eggs by rain. The largest numbers of infected Cyclops are found in Kursk, Voronezh and Tambov regions – 38 (9,84%), 21 (10,99%) и 23 (7,74%) respectively. We examined 275 animals within the study of sparganum (second larval stages) infestation of additional hosts: infected specimens were discovered in Kursk, Voronezh, Lipetsk and Tambov regions. Sparganosis was detected in two wild boars and eight grass snakes in Karachanskiy district of the Belgorod region, two grass snakes in the Usmansky district of Lipetsk region and five grass snakes in Morshansky district of the Tambov region.

Forever fissiparous: asexual propagation and stable demography in a tropical and geographically isolated asterinid sea star

Sea stars of the family Asterinidae are well known for their diverse life history strategies encompassing sexual reproduction through various larval forms, while others, all multi-armed species, through clonal asexual reproduction. For at least 25 years, a geographically isolated population of the minute (radius < 7 mm) tropical Pacific fissiparous asterinid, Ailsastra heteractis, has been locally abundant in a shallow water coral rubble habitat at One Tree Island, southern Great Barrier Reef. The population biology of this sea star was investigated over 14 years to characterise its asexual reproduction through fission (splitting in half) and to determine whether a size threshold is reached for an expected switch to sexual reproduction. Fission followed by regeneration was the dominant propagation mechanism generating individuals that varied in arm number (2–7) and length (0.5–6.9 mm). Recently split individuals were present year round with regenerating individuals being the most prevalent body form. Growth rates and fission activity, as measured by mean arm length, varied among months but with no overall pattern. Analyses of arm length data based on season indicated that fission activity was lowest in autumn. There was a positive correlation between the incidence of fission and air and water temperature with a decrease in the proportion of recently split individuals in winter and an increase in summer. Fission was present in all size classes with no evidence of a switch to a larger sexual morphotype with growth. Juvenile recruitment from sexual reproduction was not evident. Extensive searches did not reveal the presence of other populations of A. heteractis. The absence of recruitment and reproductive organs coupled with a stable population demography indicates that propagation by fission is the only reproductive mechanism for the A. heteractis population.

Severe coenurosis caused by larvae of Taenia serialis in an olive baboon (Papio anubis) in Benin.

In March 2017, a captive male juvenile (ca. 6 months old) olive baboon (Papio anubis) was brought to a primate rescue center in Benin with multiple subcutaneous swellings of unknown aetiology. At the general inspection of the body, around 15 partially mobile masses of variable sizes were found in different locations across the body. Following two surgical procedures, several cyst-like structures were removed and placed either in 10% formalin or in absolute ethanol. The cysts had a typical coenurus-like morphology. Genomic DNA was extracted from one cyst using a commercially available kit. The molecular characterization was performed by PCR amplification and sequencing of a region of the nuclear ITS-2 rDNA and a fragment of the mitochondrial 12S rDNA gene, revealing its identity as T. serialis, with 88%–98% similarity to T. serialis isolates from USA, Japan and Germany This study reports a new host for the larval form of T. serialis and confirms the role of primates as intermediate host, highlighting also the risk for human infection. Further genetic studies from multiple geographic isolates are needed to clarify the taxonomic status of this group.

Cretaceous chimera – an unusual 100-million-year old neuropteran larva from the “experimental phase” of insect evolution

Neuropteran insects possess very distinct larval stages with prominent paired piercing sucking stylets and a specialised sclerite, the neck, between the head and the first thoracic segment. Some larva of Crocinae (Nemopteridae) are further specialised by possessing a very elongated neck region. The fossil record has already provided a large variety of neuropteran larvae, yet so far a truly long-necked form was missing. Here we report such a fossil larva, with an elongated neck region from 100-million-year old Burmese amber. The specimen possesses a unique combination of characters unknown in any modern or fossil neuropteran larva. Besides the elongated neck it possesses three distinct teeth in the stylets, a character mostly known in larval forms of owl flies (Ascalaphidae) and ant lions (Myrmeleontidae), and a slender trunk as known in aphid lions (larvae of the groups Chrysopidae and Hemerobiidae). We must therefore conclude that the fossil species must have evolved certain characters in convergence to other lineages of Neuroptera resulting in a chimera-like morphology. We discuss possible interpretations of character evolution of larvae within Neuroptera.

Fine needle aspiration as a diagnostic tool in cysticercosis: a case series

BackgroundCysticercosis is a zoonotic disease. It is caused by the larval form of the pork tapeworm Taenia solium. This disease is a public health problem in a country like India, but its incidence is underestimated. With the advent of fine needle aspiration cytology with rapid on-site evaluation, early detection of this disease is possible, especially when the lesion is in anatomically approachable superficial locations.Case reportWe had four cases of cysticercosis diagnosed by fine needle aspiration cytology with on-site evaluation using toluidine blue stain, followed by Giemsa and Papanicolaou stain. Our cases included three Hindu male patients of age 30 years, 23 years, 17 years and an 26 year old Hindu female.ConclusionFine needle aspiration cytology diagnosis of cysticercosis can be easily made provided the reporting cytologist is aware of the morphological criteria. Rapid on-site evaluation can further help in taking additional material and caution during staining process.

Molecular characterisation and expression analysis of two heat-shock proteins in Taenia multiceps

BackgroundTaenia multiceps is a harmful tapeworm and its larval form (coenurus cerebralis) is the causative agent of coenurosis, a disease affecting the health of herbivores, resulting in great economic loss to animal husbandry. Heat-shock proteins (HSPs), expressed in all prokaryotes and eukaryotes, act as molecular chaperones and can affect pathogenicity.MethodsHerein, cDNAs of T. multiceps genes Tm-HSP60 and Tm-p36 were cloned and molecularly characterised by bioinformatics analyses. The immunogenicity and immunoreactivity of recombinant rTm-HSP60 and rTm-p36 proteins were investigated by immunoblotting and indirect ELISA was established to evaluate their serodiagnostic potential. Tissue localisation and transcriptional level at different life stages of T. multiceps were determined by immunohistochemical and quantitative real-time PCR analyses.ResultThe 533 residue rTm-HSP60 and the 314 residue rTm-p36 proteins share typical highly conserved features of HSPs. Tm-p36 shares structural characteristics with metazoan small HSPs, with two N-terminal α-crystallin domains. Compared with Tm-p36, Tm-HSP60 displayed stronger immunogenicity, and the indirect ELISA based on rTm-HSP60 exhibited a sensitivity of 83.3% and a specificity of 87.5%, while rTm-p36 was not suitable to develop indirect ELISA. Tm-HSP60 was widely distributed in all stages of T. multiceps, albeit at relatively low levels, while Tm-p36 was specifically distributed in the protoscolex and oncosphere.ConclusionsThe sequence, structural and functional analyses of these two HSPs indicates that they may play important roles in the life-cycle of T. multiceps as molecular chaperones. Tm-HSP60 displayed stronger immunogenicity compare to Tm-p36, and has the potential for antibody detection. Tm-p36 was strongly associated with the activation of oncospheres and has potential interest for vaccination.

Abbreviated Development of the Brooding Brittle Star Ophioplocus esmarki.

The bilaterally symmetrical, feeding larval stage is an ancestral condition in echinoderms. However, many echinoderms have evolved abbreviated development and form a pentamerous juvenile without a feeding larva. Abbreviated development with a non-feeding vitellaria larva is found in five families of brittle stars, but very little is known about this type of development. In this study, the external anatomy, ciliary bands, neurons, and muscles were examined in the development of the brooded vitellaria larva of Ophioplocus esmarki. The external morphology throughout development shows typical vitellaria features, including morphogenetic movements to set up the vitellaria body plan, an anterior preoral lobe, a posterior lobe, transverse ciliary bands, and development of juvenile structures on the mid-ventral side. An early population of neurons forms at the base of the preoral lobe at the pre-vitellaria stage after the initial formation of the coelomic cavities. These early neurons may be homologous to the apical neurons that develop in echinoderms with feeding larval forms. Neurons form close to the ciliary bands, but the vitellaria larva lacks the tracts of neurons associated with the ciliary bands found in echinoderms with feeding larvae. Additional neurons form in association with the axial complex and persist into the juvenile stage. Juvenile nerves and muscles form with pentamerous symmetry in the late vitellaria stage in a manner similar to their development within the late ophiopluteus larva. Even though O. esmarki is a brooding brittle star, its developmental sequence retains the general vitellaria shape and structure; however, the vitellaria larvae are unable to swim in the water column.

Schistosomicidal and prophylactic activities of phthalimido-thiazoles derivatives on schistosomula and adult worms

Schistosomiasis is a major public health problem worldwide, especially in poor communities. Praziquantel is currently the only drug available to treat schistosomiasis and it shows low efficacy against schistosomula and juveniles stages of Schistosoma mansoni, allowing lower cure rate in areas with high endemicity. There is an urgent need to identify new antischistosomal drugs. Previous works identified phthalimido-thiazoles as privileged structures acting as schistossomicidal agent. In this way, a phthalimido-thiosemicarbazide intermediate and eight phthalimido-thiazoles derivatives were evaluated concerning the in vitro antischistosomal activity compounds in adult phase of Schistosoma mansoni and examined alterations on the tegumental surface. The results revealed that compounds 2f, 2 l and 2 m caused significant mortality in adult worms at concentrations range of 20 μg/mL to 100 μg/mL. These compounds were also selected in view to verify the activity against the schistosomula. Compound 2 m promoted 100% of mortality of larval forms until doses of 2.5 μg/mL within 48 h. In addition, when compound 2 m was administered orally at dose of 200 mg/kg for 5 consecutive days to the infected mouse with adult schistosomes, a reduction in the parasite burden was observed. Furthermore, scanning electron microscopy revealed that compound 2 m kill the parasite by tegumental damage and bubbles generation.

Baylisascaris procyonis infection in raccoons: A review of demographic and environmental factors influencing parasite carriage.

Baylisascaris procyonis, the roundworm of raccoons (Procyon lotor), is an emerging helminthic zoonosis in North America. Since the larval form is capable of causing neurological disease in more than 150 species of birds and mammals including humans, understanding factors that influence carriage of the parasite by raccoons is important for mitigating risk. This review examines the current literature to identify major demographic and environmental risk factors associated with B. procyonis carriage in wild raccoons. Raccoon age and season of sample collection were most commonly identified as risk factors, with increased prevalence found in juvenile animals and when sample collection occurred in the fall. Human urbanization and agricultural land use were also observed as potential risk factors; however, there are inconsistencies in the direction of influence these risk factors have on the prevalence of infection. Further investigation into the role of environmental risk factors is required to better understand how human activities influence parasite carriage in raccoons. Additionally, future research using multivariable statistical models guided by epidemiological principles to control for confounding variables and identify interaction effects will help clarify the effect of these demographic and environmental factors. Developing a better understanding of the primary risk factors for parasite carriage in raccoons will help identify areas of higher risk for environmental contamination and will aid in the development and refinement of education and management programs to reduce the risk of human exposure.

Automated behavioural analysis reveals the basic behavioural repertoire of the urochordate Ciona intestinalis

Quantitative analysis of animal behaviour in model organisms is becoming an increasingly essential approach for tackling the great challenge of understanding how activity in the brain gives rise to behaviour. Here we used automated image-based tracking to extract behavioural features from an organism of great importance in understanding the evolution of chordates, the free-swimming larval form of the tunicate Ciona intestinalis, which has a compact and fully mapped nervous system composed of only 231 neurons. We analysed hundreds of videos of larvae and we extracted basic geometric and physical descriptors of larval behaviour. Importantly, we used machine learning methods to create an objective ontology of behaviours for C. intestinalis larvae. We identified eleven behavioural modes using agglomerative clustering. Using our pipeline for quantitative behavioural analysis, we demonstrate that C. intestinalis larvae exhibit sensory arousal and thigmotaxis. Notably, the anxiotropic drug modafinil modulates thigmotactic behaviour. Furthermore, we tested the robustness of the larval behavioural repertoire by comparing different rearing conditions, ages and group sizes. This study shows that C. intestinalis larval behaviour can be broken down to a set of stereotyped behaviours that are used to different extents in a context-dependent manner.

Tissue damage and cytotoxic effects of Tagetes minuta essential oil against Lucilia cuprina

The blowfly Lucilia cuprina has great medico-sanitary and veterinary importance due to the ability of its larval form to develop in decaying organic matter, parasitizing vertebrates. Fly eradication is challenging and the essential oil (EO) of Tagetes minuta (TMEO) have been reported to have therapeutic properties. This study aimed to determine the activity of EO from the aerial parts of T. minuta against third instar larvae (L3) of L. cuprina. Groups of 20 L3 were placed on filter paper, which were impregnated with varying concentrations (0.19; 0.39; 0.79; 1.59; 2.38; 3.18; 4.77; and 6.36 μL/cm2) of TMEO solubilized in acetone, ethanol or Tween 20. Histological tissue damage of TMEO was measured in L3 after 24, 48 and 96 h of exposure. Dihydrotagetone (67.64%), trans-ocimene (16.23%), trans-tagetone (10.14%) and verbenone (2.98%) were obtained as major compounds of TMEO. Lethal concentrations of 50%, 24 and 48 h after TMEO exposure were 1.02 and 0.73 μL/cm2 for acetone; 3.37 and 1.75 μL/cm2 for ethanol; and 7.46 and 6.11 μL/cm2 for Tween 20, respectively. TMEO had a significant L3 mortality of 96.6% in acetone, 48 h after contact. Cuticle abnormalities were observed, as well as the loss of digestive tract architecture and vacuolization in fat bodies. TMEO presented time and concentration-dependent effects against L. cuprina. As our study demonstrated a strong insecticide activity of TMEO, we consider that it could be developed into an ecofriendly product against L. cuprina.

Update on neurocysticercosis

Neurocysticercosis (NCC) caused by the larval form of the cestode parasite Taenia solium is common among immigrant populations from endemic regions including Latin America, sub-Saharan Africa, and parts of Asia. In endemic areas, it is linked to approximately 29% of cases of adult-onset seizures. More than 2000 cases per year are identified in the United States, but the prevalence among Australians is unknown. Humans can be hosts to both the tapeworm form and larval forms of the parasite. Taeniasis refers to infestation of the human intestines with the tapeworm form, acquired by ingestion of larval worms in undercooked pork. Cysticercosis refers to infection of the tissues with larval cysts. Normally, pigs host the cysts, acquired by ingestion of ova or proglottids from human faeces. However, humans can be infected by ingestion of ova and develop cysticercosis. NCC refers to cysticercosis involving the central nervous system, including the brain parenchyma, ventricles, spine, and retina. In this presentation we will discuss the pathogenesis, natural history, clinical manifestations, and management of NCC. Recent discoveries from clinical and laboratory investigations have prompted the development of guidelines by the Infectious Diseases Society of America that can inform us in the diagnosis and management of NCC in immigrant populations.

Ultrasonography as the First Method of Choice in the Diagnosis of Primary Extrahepatic Echinococcosis: Case Report

The aim of this presentation is to show the high informative value of ultrasonography as the first method of choice in the diagnosis of atypical extra-hepatic forms of echoconcosis. Echinococcosis is zooanthroponosis and is most commonly caused by the larval form of E. granulosus. Echinococcal cysts develop, most commonly in the human liver and second - in the lung. Rare primary localization is echinococcus cysts of greater omentum and spleen. Ultrasonography is first method of ch?ice for diagnostic. The main clinical and laboratory diagnostic methods are immunoelectrophoresis and serological evidence of echinococcosis by ELISA. Timely surgical treatment give it a chance to cure. The use of post-operative antiparasitic chemoprophylaxis and therapy is recommended.

Neonatal Cutaneous Myiasis: A Mistaken Identity for Impetigo

Introduction: Myiasis is a parasitic infestation of the animal body by fly larvae that grow inside the host and feed from its tissue. Myiasis occurs when eggs laid by female flies come in contact with the human skin where they feed and develop into the larvae. Greater numbers are noted in the less-developed countries where environmental hygiene remains a problem. Case Report: A case of a previously healthy 10-day old female neonate delivered in a specialist hospital but was infested by the larval forms of the blowfly with over 50 papules widely distributed to all parts of the body excluding the diaper area which was initially mistaken for impetigo. Conclusion: This case is to heighten the index of suspicion in this category of babies especially in endemic settings and reiterate the need to handle newborn clothing with better care such as ironing especially where such articles are aired in the open.

Primary Closure of Infected Wound Infested by Fly Larvae—Case Report in Dog

One of the most common aggravating factors of wounds is the myiasis. Flies lay their eggs on the wound, they hatch and release a larval form of the dipteran, which feeds on host tissues leading to necrosis and large production of exudate, thus, it is an extremely pleasant environment to bacterial multiplication. The aim of this study was to describe the case of a dog that displayed an infested larvae ulcerated tumor in the ocular region. Successful results were obtained when performing surgical treatment of the wound with healing by primary closure. The 13-year-old female dog, 30 kg, was brought to the Veterinary Clinic of Ingá University Center, Maringá-PR, Brazil, with the main complaint of an ulcerated left ocular tumor. The owner could not tell when the problem had started. After the patient’s physical and laboratory evaluation, which were within normal parameters, enucleation was scheduled for tumor removal. On the day of surgery, the owner reported large mucopurulent secretion and foul odor at the site. The patient was taken for the larvae removal surgical procedure and later enucleation. The wound was debrided and washed with physiological solution, and then tarsorrhaphy was performed and a Penrose drain was applied. The animal returned 15 days later with the wound fully healed. As a conclusion with the current report, the primary closure treatment with the use of drain after intense debridement of a fly larvae infected wound can be a good alternative, especially when it is aimed at faster healing.

Economic evaluation of a program for monitoring and controlling Trichinella in pigs

Introduction. Trichinellosis is a cosmopolitan anthropozoonosis, and is a group of systemic diseases caused by larval forms of Trichinella. This is one of the oldest and most controversial parasitic zoonoses that has been in the forefront of veterinary, medical and biological research for many years. Parasites from the genus Trichinella were diagnosed in more than one hundred species of domestic and wild mammals and birds. The aim of this study was economic evaluation of a program for monitoring and controlling Trichinella in pigs. Materials and Methods. A systematic pest rodent control program deemed suitable for monitoring and controlling Trichinella in pigs was implemented in a representative test zone. The results of the pest rodent control program were analyzed using cost-benefit analysis to determine if a similar program would be suitable for a larger land area. Results and Conclusions. Prior to pest control, the incidence of Trichinella in pigs living in the test zone increased annually, while after systematic pest rodent control, the incidence of Trichinella-positive pigs decreased. These results, as well as relevant economic indicators, enabled us to design two mathematical models describing the control and monitoring of Trichinella in a larger land area. In this area, Srem Region, Serbia, a suitable Trichinella control program in pigs is clearly justified because the profit to cost ratio was positive for both models.

Epidemiology of lung parasites of European brown hare (Lepus europeus L.) from Bulgaria

During the period 2009–2016, seven hundred and ninety lungs from brown hares (Lepus europeus L.) from different regions of Bulgaria were investigated for presence of parasites. The results showed that 11.14% of the lungs were parasitised. Four parasite species were established: two nematodes – Protostrongylus tauricus and P. cuniculorum (recorded for the first time as a part of the helminth fauna of the country), one cestod – larval form of Taenia pisiformis – Cysticercus pisiformis and one arthropod – larval form of Linguatula serrata – Pentastomum denticulatum. The infected hares came mainly of the south parts of the country. The highest prevalence of infection was observed in the South West region, followed by the South Central and South East regions. From the northern parts of the country parasites were established only in the northeastern districts near to Black Sea and Danube River. The ratio of prevalence of infection in female vs male animals was 1.4:1. Infections with protostrongylids and cysticerci were established at the earliest in hares at the age of 4–6 months and with P. denticulatum: in hares between 7 and 9 months. The prevalence of infection varied in animals from the different age groups. The highest prevalence of infection was observed in the young (4–6 months) and adult hares (over 3 years of age).