Histochemistry and ultrastructure of the metacercarial cyst of Bolbogonotylus corkumi (Trematoda: Cryptogonimidae).

Histochemical and ultrastructural studies were conducted on the metacercarial cyst of the cryptogonimid trematode Bolbogonotylus corkumi from the muscle tissue of fantail darters Etheostoma flabellare. The metacercarial cyst consisted of an outer host capsule and an inner parasite cyst. The host capsule was composed of an outer region of fibroblasts, collagen, macrophages, and unidentified cells, and an inner region containing degenerating cells. The parasite cyst was thin, homogenous, and noncellular in nature. The host capsule stained strongly for connective tissue and proteins and moderately for lipids, nucleic acids, nonspecific esterase activity, and acid and alkaline phosphatase activities. The parasite cyst stained intensely for acid mucopolysaccharides and moderately for acid phosphatase activity. A thick glycocalyx occurred between the parasite cyst and metacercarial tegument.     

Malformations and mortality in the Asian Common Toad induced by exposure to pleurolophocercous cercariae (Trematoda: Cryptogonimidae)

Malformations and increased mortality due to infection by the digenetic trematode, Riberioa ondatrae have been reported for many species of amphibians. Severe malformations have also been reported in the Common Hourglass Tree Frog, Polypedates cruciger induced by pleurolophocercous cercariae in Sri Lanka in addition to the changes in the behaviour, development and survival of the host. We exposed pre-limb bud stage tadpoles (Gosner stages 25–26) of the Asian Common Toad, Duttaphrynus melanostictus to the same pleurolophocercous type cercariae under laboratory conditions. Molecular and morphological identification showed that these cercariae belonged Acanthostomum burminis infecting freshwater snakes as definitive hosts. These cercariae induced malformations (27.8%) and reduced survival to metamorphosis (53.8%). The magnitude of the effects increased with the dose of cercariae. Types of malformations were mainly axial, such as scoliosis and kyphosis. Severe limb malformations such as extra or missing limbs as reported for amphibians exposed to R. ondatrae were not observed in the D. melanostictus. Same authors reported a higher percentage of malformations previously when P. cruciger was exposed to the cercariae A. burminis compared to D. melanostictus. However, tadpoles of D. melanostictus, which are smaller compared to those of P. cruciger, experienced higher mortality than P. cruciger tadpoles. Trematode induced malformations and mortality in amphibians are highly variable and depend on multiple factors such as host species differences such as resistance to infection and tolerance, life-history characteristics such as size at metamorphosis and length of the metamorphosis period, and other factors such as size of the amphibian at the time of trematode exposure.     

Diphtheria in the Maritime Territory

The results of the analysis of the present epidemiological situation in diphtheria in the Maritime Territory are presented. The data on absolute and intensive characteristics, death rate due to this infection, the vaccination status of diphtheria patients, as well as the results of the study of the level and intensity of antidiphtheria immunity in the healthy population of the territory. The study revealed that the defects of collective antidiphtheria immunity correlated with morbidity rate among adults and children. Adults aged 40-50 years and children aged 6-7 years were regarded as risk groups; among them the highest proportion of nonimmune persons and the highest diphtheria morbidity rate were registered. Stabilization achieved by the present moment was the result of the mass immunization of the adult population, ensuring the necessary coverage (92%) of vaccination in 1995.     

Tick-borne encephalitis in the Maritime Territory

On the basis of epidemiological analysis carried out at the period of 1940-1987, a decrease in tick-borne encephalitis (TBE) morbidity was registered; at the same time time the disease invariably took, as before, a clinically severe course. The most dangerous foci of TBE were found to be located in the southern Okhotsk region grown with dark coniferous forests. The subsiding and activation of the natural foci of TBE in different regions of the territory were established and some heretofore unknown foci in southern regions of the Maritime Territory were found. Ixodes mites inhabiting the Maritime Territory were shown to have a low level of virus carriership, thus causing the low level of population immunity to TBE virus. Combined foci of TBE and Powassan encephalitis were found.     

The ultrastructure of the spermatozoon of Neochasmus sp. (Cryptogonimidae, Digenea, Trematoda) and its phylogenetic significance

Jamieson B. G. M. and Daddow L. M. 1979. The ultrastructure of the spermatozoon of Neochasmus sp. (Cryptogonimidae, Digenea, Trematoda) and its phylogenetic significance. International Journal for Parasitology12: 547–559. The typical spermatozoon is filiform, monopartite and internally strongly asymmetrical, with a mean length of 254 μm. Its two axonemes are wholly incorporated though not deeply. The six major regions, in anteroposterior (proximal-distal) sequence, are: acrosomoid, prenuclear, uniaxonemal, nuclear, intermediate (amitochondrial), posterior mitochondrial and posterior amitochondrial regions. Centrioles and flagellar rootlets, present in the spermatid, are absent from the spermatozoon. The right axoneme (axial unit) originates more anteriorly than the left and anteriorly bears an acrosome-like projection (acrosomoid). Spinose regions carrying epiplasmalemmal projections are reported for the first time in the Digenea. Dimorphism exists as replacement of the typical posterior mitochondrial and amitochondrial regions by an amitochondrial region characterized by asymmetrical distribution of spines around one axoneme. Excepting known schistosomatid sperm, the digenean sperm is diagnosed by the combination of three characters: cortical microtubules, two fully incorporated 9 + 1 axonemes and presence of mitochondria although no one of these characters is limited to the group. Subtle intertaxon variations occur.     

The developmental cycle of the trematode Glypthelmins rugocaudata (Plagiorchidae) under the conditions in the Maritime Territory

It is found out, that the life cycle of the trematode Glyphthelmins rugocaudata (Yoshida, 1916) in the Primorye region includes two intermediate hosts (mollusc Lymnaea pacifampla and dragonfly larvae of the genera Cordulia and Lestes) and a final host, frog species Rana migrimaculata and R. semiplicata.     

Siphoderina hustoni n. sp. (Platyhelminthes: Trematoda: Cryptogonimidae) from the Maori snapper Lutjanus rivulatus (Cuvier) on the Great Barrier Reef

A new cryptogonimid trematode, Siphoderina hustoni n. sp., is reported, collected off Lizard Island, Queensland, Australia, from the Maori snapper Lutjanus rivulatus (Cuvier). The new species is moderately distinctive within the genus. It is larger and more elongate than most other species of Siphoderina Manter, 1934, has the shortest forebody of any, a relatively large ventral sucker, a long post-testicular zone, and is perhaps most recognisable for the substantial space in the midbody between the ventral sucker and ovary devoid of uterine coils and vitelline follicles, the former being restricted to largely posterior to the ovary and the latter distributed from the level of the anterior testis to the level of the ovary. In phylogenetic analyses of 28S ribosomal DNA, the new species resolved with the other nine species of Siphoderina for which sequence data are available, all of which are from Queensland waters and from lutjanid and haemulid fishes. Molecular barcode data were also generated, for the ITS2 ribosomal DNA and cox1 mitochondrial DNA markers. The new species is the first cryptogonimid known from L. rivulatus and the first metazoan parasite reported from that fish in Australian waters.

     

Fauna of dust-dwelling mites in the Maritime Territory

The specific composition of acarid mites occurring in dust of rural dwellings in the Far East of the USSR has been first studied and characters of their fauna have been revealed. 3 species are most frequently encountered of which Dermatophagoides pteronyssinus accounts for 56% of all finds. 6 species happened to be new for the fauna of dwellings. The typical synanthropic species Glycyphagus domesticus is totally absent from dwellings but occurs in 90% of honey-bee hives.     

Immunologic monitoring of leptospirosis in the Maritime Territory

The epidemiological and epizootic situation in Leptospira infections at the Maritime [correction of Primorski] Territory is evaluated on the basis of complex studies carried out in 1984-1989. As revealed in these studies, cases of leptospirosis among humans have a sporadic character and are mainly registered among professional high risk groups of the population. In the immunological structure of persons covered by the survey L. hebdomadis, L. pomona and L. javanica prevail. The anthropourgic foci of leptospirosis caused by L. pomona are of the leading epidemiological importance. Swine serves as the main source of infection in these foci. The study revealed the epidemic danger of the natural foci of leptospirosis caused by L. grippotyphosa and L. javanica in rice fields where the decisive factors of leptospirosis proved to be reed voles and striped field mice serving as reservoirs of this infection, as well as the synanthropic foci of leptospirosis caused by L. hebdomadis with house mice serving as the main carriers.     

Medico-genetic characteristics of the Udegey in the Maritime Territory

The results of medico-genetical investigation of Udegey population of Primorski territory were described. These studies were carried out by Moscow Institute of Medical Genetics. Marriage structure of population investigated was studied which demonstrated a low level of inbreeding and high frequency of intranational marriages. The structure of population morbidity was characterized by the absence of accumulation of specific hereditary pathology. Data obtained are of great interest for comparative analysis of populations of a different marriage structure.     

The biology of the trematodes Nenimandijea kashmirensis and Pleurogenoides medians (Pleurogenidae)--parasites of frogs in the Maritime Territory

The experimental study of life cycles of the trematodes Nenimandijea kashmirensis Kaw, 1950 and Pleurogenoides medians Olsson, 1876 was carried out. It was found out, that their life cycles include: the first intermediate host--the mollusc Boreoelona contortrix ussuriensis, the second intermediate host--dragonfly larvae of the genus Cordulia, and the final host--the frogs Rana nigrimaculata and R. semiplicata. Based on obtained data it is suggested, that Pleurogenoides japonicus (Yamaguti) should not be considered as a separate species.     

A focus of human infection by Haplorchis taichui (Trematoda: Heterophyidae) in the southern Philippines

We report an exceptionally high rate of infection by Haplorchis taichui (Nishigori, 1924) in human populations on Mindanao Island, southern Philippines. This intestinal fluke is seldom encountered, and this is the first report of high prevalence of infection (36%) in humans by H. taichui in the Philippines. The likely source of haplorchine infection has been linked to consumption of raw or undercooked freshwater fish containing infective metacercariae. The most common clinical symptoms appeared as upper abdominal discomfort or pain and borborygmi. Praziquantel (75 mg/kg divided in 3 doses in 1 day) was a well-tolerated and effective treatment for infection by H. taichui.     

Clinico-epidemiological characteristics of tick-borne encephalitis in the Maritime Territory

Clinico-epidemiological analysis of tick-borne encephalitis (TBE) incidence rate in the Primorski Territory for 25 years has revealed the prevalence of focal forms of this infection (on the average, 50%) and its high mortality rate (on the average, 33% for the focal forms and 6.4% for the meningeal form). Such course and termination of this infection depend not only on the reactive capacity of the patient's body, but, to a great extent, on the virulence of TBE virus circulating in the area under study.     

The spatial-temporal structure of fluctuations in tick-borne encephalitis morbidity in the Maritime Territory

The annual dynamics of the epidemic process in tick-borne encephalitis and its spread in the Maritime Territory, endemic for this infection, have been studied. The study has shown that in the central mountainous regions grown with boreal forest, in contrast to the rest of this focal area, a higher morbidity level and more severe outcomes of this infection are observed. This indicates that in those regions more ancient nuclei of the endemic area of this infection with the main stable elements of the natural focus are preserved.     

The efficacy of vaccination and serotherapy in tick-borne encephalitis in the Maritime Territory

The use of different vaccines manufactured in the USSR under the condition of the Far East has revealed that killed vaccines do not produce a protective effect, sufficient for the prophylaxis of tick-borne encephalitis (TBE). This is probably due to the circulation of a highly virulent population of TBE virus at the Territory. This virus population may produce a severe course of infection and aggravate the clinico-epidemiological characteristics of the effectiveness of vaccines. Besides, low levels of specific and nonspecific humoral resistance factors in the residents of the Far East, especially in spring and summer, contribute to this fact. The negative effect of specific serotherapy for persons over 40 years of age has been established.