The reliability of Stoll's dilution egg count technique, Beaver's direct smear technique and Katz's modified thick smear technique were evaluated on patients with ascariasis. Studies revealed that the modified thick smear technique appears to be more reliable and accurate. The use of these three techniques revealed a significant correlation between the number of eggs per gram (e.p.g.) and worm load. Following the introduction of a standardized factor in a study of 30 patients with worm infections, a highly significant correlation was obtained between the e.p.g. and the worm load for all three techniques. The use of a Standardized Factor is recommended for better prediction of the worm burden. The results of this study reveal that a female Ascaris lumbricoides lays an average of 218,094 (range 82,251–365,200) eggs daily. The ratio of male to female A. lumbricoides was 1:1·4

Six nocturnal microfilarial carriers (three with Wuchereria bancrofti and three with Brugia malayi) from mainland China were selected to determine the earliest appearance and peak count of microfilariae (mf) administration of DEC at noon. Before diethylcarbamazine (DEC) administration, blood samples of 60μl were obtained by finger-prick at 2 h intervals for 24 h. A blood sample was then taken just before each carrier intaking 100 mg, 150 mg or 200 mg of DEC orally at noon. After drug administration, blood samples were obtained at 45 and 60 sec and at 2, 3, 4, 5, 10, 15, 20, 25, 30, 40, 50, 60, 90 and 120 min. Samples were then taken at 2 h intervals for the next 2 h and at 6 h intervals for the next 7 days. Both W. bancrofti and B. malayi showed typical nocturnal periodicity. One mf was first detected in the peripheral blood 45 sec in a mf. carrier. The mf peak counts were found 1–40 min after DEC administration at noon. The nocturnal cycle was distributed during the first two days after DEC administration. It became regular with a much lower peak count by the third day after administration. The results of the present study indicate that the provocative effect of DEC on the mf is very fast; the first appearance in the peripheral blood vessels could be under 45 sec.

The component community of larval trematodes in the freshwater snail Semisulcospira nakasekoae (Caenogastropoda: Sorbeoconcha: Pleuroceridae) was surveyed over 13 months from April 1996 to April 1997 inclusive. Temporal and spatial fluctuation of trematode prevalence, the frequency of multiple infections, and the duration of cercarial shedding were examined as factors that might affect trematode community structure. The spatial prevalence of some species varied significantly, but the dynamics were too small to allow an explanation of the overall pattern. The prevalence of sanguinicolids fluctuated temporally, despite a stable size distribution in the host populations (> 6.0 mm shell width), suggesting the life-cycle phenology of this species. Some pairs of species had statistically positive associations, but no pairs had negative associations. This shows the importance of positive association possibly as a result of suppression of the host defensive response on trematode community structures in molluscan hosts. The length of the patent period, which is part of the persistent period, varied among trematode species, suggesting it to be one of the factors determining prevalence in the host population.

1. The susceptibility of two strains of rats, namely London-hooded and Wistar, to infection with S. mansoni has been investigated

2. Although equal numbers of cercariae penetrated the skin in both strains, recovery of worms was always higher from the London-hooded strain irrespective of the dosage level.

3. In both strains there was a significant relationship between body weight at time of infection and number of worms recovered. The correlation was a negative one, indicating that lighter (younger) rats were more susceptible than heavier (older) rats.

4. A rapid rate of elimination of infection was demonstrated in London-hooded rats between the 4th and 8th week after infection.

The overall goal of this study was to use the Rattus spp./Hymenolepis diminuta model to assess environmental lead pollution in different landscape units of an urban ecosystem. Rats of the genus Rattus were collected from three shanty towns and three residential neighbourhoods of the city of Buenos Aires. Concentrations of lead in the livers of wild rats and in their parasite H. diminuta were measured using inductively coupled plasma mass spectrometry (ICP-MS). The landscape unit and tissue type had a significant effect on lead concentration, being higher in residential neighbourhoods as well as in H. diminuta tissue. Nevertheless, no significant differences were found for the mean lead concentration in livers between uninfected and infected rats. Since the available information describing heavy-metal pollution within the city of Buenos Aires is scarce, the results of this study allow us to update data about the extent of biologically available lead contamination. Considering that rats and H. diminuta are distributed worldwide, this monitoring system for lead pollution might be applied successfully in other urban ecosystems.

Anguillulina has been revived by Baylis and Daubney (1926) as the correct generic name for those worms which for many years have been considered as belonging to the genus Tylenchus, at least by most specialists on nematodes and plant-pathologists. Gervais and van Beneden on pp. 101 and 102 of the second volume of their work Zoologie Médicale, published in 1859, gave a brief account of the eelworm parasite of wheat causing “purples” or “cockles” and that found by Kuhn in 1858 in the heads of the fuller's thistle, teasle, both of which they designate as Anguillulines (Anguillulina) as follows:—Anguillilina tritici and Anguillulina dipsaci.

It may be pointed out, in passing, that they were not consistent in the use of the word, for at the end of the description of A. dipsaci they spell it as Anguillula not Anguillulina. This may, however, perhaps be regarded as an unintentional slip or a printer's error. Bastian's paper in which first the name Tyleenchus and then Tylenchus is applied to members of this genus appeared in 1865 and he designated Tylenchus davainii as type species of the genus in a letter to Stiles dated March 22nd, 1904, vide Stiles and Hassall (1905).

One hundred and six of 109 common shrews (Sorex araneus) and 62 of 72 pygmy shrews (S. minutus), obtained by Longworth trapping in Southeast England, were infected with cestodes. Ten species were recovered: Choanotaenia hepatica and Hymenolepis prolifer (found in S. araneus); Choanotaenia crassiscolex, Hymenolepis furcata, H. jacutensis, H. schaldybini, H. scutigera, H. singularis, H. diaphana and H. infirma (in both hosts). The morphology, taxonomy and ecology of these species are discussed and the findings of the present study are discussed with reference to previous studies of the helminth fauna of British shrews. Cysticercoids of C. crassiscolex were found in the snail, Vitrina pellucida, and cysticercoids of H. schaldybini in the staphylinid beetle, Anthobium unicolor.

Habitats characterized by geographic isolation such as islands have been studied using different organisms as models for understanding the dynamic and insular patterns of biodiversity. Determinants of parasite richness in insular host populations have been conducted mainly with mammals and birds, showing that parasite richness decreases in insular areas. In the present study, we predicted that the type of environment (insular or continental) can influence the richness, diversity and abundance of parasites associated with the endemic frog Haddadus binotatus (Spix, 1824). We sampled frogs in two insular and two mainland fragments to survey their helminth parasites. The total richness was composed of 15 taxa of Nematoda and two of Acanthocephala, and the community composition of the two islands had more similarities between them than the two mainland localities. The insular effect was positive for richness and abundance of helminths, and no significant effect was observed on helminth diversity – even the mean diversity presented high numbers for the islands. We presumed that insular hosts could have lost some parasites in the colonization process when these continental islands were separated from the mainland, approximately 11,000 years ago. However, the high richness and abundance on islands can be explained by an epidemiological argument, which considers high population density due to insularity and other features of the host as factors that increase parasite transmission success among individuals.

Since the exogenous compound tris(hydroxymethyl)aminomethane (Tris) showed a potent chemoattractant activity for Brugia pahangi infective third-stage larvae (L3), it was assumed that, in natural infection to a host, filarial L3 can be expected to recognize an endogenous Tris-related compound. In addition, a few amino acids have been identified as water-soluble attractants for second-stage juveniles of Meloidogyne incognita, a plant parasitic nematode. Therefore, the present study assesses the in vitro chemotactic responses of B. pahangi L3 to Tris-related compounds and amino acids using an agar-plate assay. Among Tris-related compounds, 2-amino-1,3-propanediol (APD) and 2-amino-2-methyl-1,3-propanediol (AMPD) exhibited a potent chemoattractant activity for filarial L3 at a level similar to Tris. Furthermore, arginine (Arg) was identified as a potent attractant for filarial L3 among amino acids. In addition, filarial L3 were attracted to Arg, APD and AMPD in mild alkaline conditions rather than acidic conditions. The chemoattractant activity of the three compounds for filarial L3 was observed in concentrations between 6.3 and 200 mm. This is the first report to demonstrate that Arg, APD and AMPD are potent chemoattractants for B. pahangi L3. Endogenous Arg and APD, in particular, may be involved in the regulation of the chemotactic behaviour of filarial L3 in the infection to a host. The present results will help to elucidate the mechanism of filarial skin-penetrating invasion of a host.

Fifty-five warthogs [Phacochoerus aethiopicus (Suidae: Artiodactyla)] from the Kruger National Park, Republic of South Africa, were examined for parasites. Adult filarial nematodes were found in lymphatic vessels adjacent to peripheral and visceral lymph nodes, and microfilariae were found in lymph nodes and circulating blood. Both the adult parasite and the microfilaria are described. Specific identification is pending confirmation and recovery of intact adult specimens and microfilariae identical to those described herein.

Neostrigea africana gen.et sp.nov., Neostrigea leiperi gen.et sp.nov. and Prostrigea arcuata gen.et sp.nov. are described from the intestine of Crocodilus niloticus, Kafue River, Northern Rhodesia. The three species are included in two new genera which are placed in a new family Neostrigeidae.

1. A new species, Anthobothrium taeniuri n.sp., has been described from the spiral intestine of the sting ray, Taeniura lymma from the Red Sea and compared with related species.

2. The two genera Rhodobothrium Linton, 1889 and Inermipyllidium Riser, 1955 are considered to be synonyms of Anthobothrium van. Beneden, 1850.

In water extracts of turf from one of the meadows at this Institute made May and November, 1941, several specimens of a new dorylaimid nematode were obtained. They were noticeable even under low magnification by reason of the elongated mouth spear and the shape of the tail. Females only have been found. Study of freshly-killed and well preserved specimens showed that they belong to the genus Pungentus of Thorne & Swanger (1936). As, however, they do not agree structurally with any of the species described by Thorne & Swanger (l.c.) and by Thorne (1939), a new species is erected for their reception. The worms are named in honour of Dr. Gerald Thorne, who in the two monographs just cited has added so materially to our knowledge of the soil nematodes belonging to the superfamily Dorylaimoidea.

One hundred and six trees suffering from Red Ring disease were examined and the distribution of worms plotted. The results indicate that infection can start in either the root system or in the upper part of the tree. The distribution of worms in 21 of the trees examined was consistent with the disease starting in the base of the tree; and 5 trees exhibited conditions consistent with infection starting in the upper part of the tree. Of thirteen trees, more than 20 years old, one was found to be infected in the top only; the other carried an infection in the roots and lower stem. It is concluded that the disease can start in either the top of a tree or in the root system but for reasons given in the text, it is not possible to say which is the more frequent.

Gyrodactylus alviga is a generalist species reported in many Black Sea fish species, but whiting is known to be its main host. It is the only monogenean parasite that has been reported so far on the skin, fins and gills of whiting Merlangius merlangus in the Black Sea. A total of 690 fish from Turkey and 423 fish from Russia were examined to detect parasites. Infection indices of prevalence, mean intensity and mean abundance values were calculated for length classes and sex of fish, as well as for the seasons. There is a gradual increase in infection indices in relation with increasing host length classes and there are higher infection indices on female fish. Furthermore, despite lower prevalence indices in spring and winter, higher parasite intensity values were determined in these seasons. It is concluded that larger fish provided more space and food for G. alviga, and female fish were more parasitized as they were more active in searching for food, which enables the parasite to switch between hosts. In addition, winter and spring were more appropriate for reproduction of G. alviga.

Paraoligorchis taterae gen. et sp.n. is described from the Indian gerbil Tatera indica. It is characterised by unarmed suckers; rudimentary and unarmed rostellum; 4–7 testes of which 1–2 are aporal and anterior to others which are in a transverse row; cirrus pouch extending beyond excretory stems; unilateral genital pores; genital ducts dorsal to excretory stems; prominent external and internal seminal vesicles; large rosette-like ovary; saccular uterus; vaginal opening posterior to that of the cirrus pouch; three-layered eggs devoid of both a pyriform apparatus and polar filaments. It has been compared with related genera of Hymenolepidinae and Anoplocephalinae and found to differ from all of these in some character or other.

This study evaluated the existence of different genotypes of Haemonchus contortus prevailing among goats in West Bengal, India. These parasites were isolated from the abomasum of goat intestine and the molecular characterization was performed by comparing variation of nucleotide sequences of the internal transcribed spacer 1 (ITS-1) gene region. Single-strand conformation polymorphism (SSCP) analysis of ITS-1 amplified product showed the presence of three distinct conformations both in male and female parasites. The sequence analysis of conformations showed two single nucleotide polymorphisms (SNP) in male parasites at nucleotide positions 106 and 107 and one SNP was detected in female parasites at nucleotide position 157. These nucleotide variations in different isolates did not alter the interior loop structure of the predicted secondary RNA, therefore we believe these variations may not be responsible for any evolutionary changes among conformations.

We describe the first case of angiostrongyliasis in a water rat, Hydromys chrysogaster, a large rodent adapted to aquatic life, which is endemic to Australia, New Guinea and adjacent islands.

The tegument of schistosomes is a source of many potential anti-Schistosoma vaccine molecules. This work aimed to assess the protective effects of the adult Schistosoma mansoni tegument treated (TT) with sub-curative praziquantel (PZQ), whether in vivo (in vivo TT) or in vitro (in vitro TT), in murine schistosomiasis. In vitro TT and in vivo TT showed great similarity, and they differed from untreated tegument antigen (Teg) in terms of quantity and quality of protein bands on SDS–PAGE. Two immunization trials were performed, each with 50 mice, divided randomly into five groups of 10 mice each: (1) uninfected control mice (UC), (2) infected mice given phosphate buffer saline + adjuvant (PBS + adjuvant), (3) infected, Teg vaccinated, (4) infected, in vivo TT vaccinated, and (5) infected, in vitro TT vaccinated. All the immunizations with antigens induced mixed Th1/Th2 immune responses, as indicated by significantly high (P < 0.001) specific IgG2a and IgG1 levels, with Th1 predominating, as shown by a diminished IgG1/IgG2a ratio, as well as a high serum concentration of IFN-γ, an absence of IL-4 and increased IL-10. In vitro TT gave the most pronounced response. With respect to reduction of total worm burden, relative to PBS + adjuvant mice, in vitro TT achieved the highest significant (P < 0.001) results, followed by in vivo TT and Teg (51.8–57.04%, 44.6–50.2% and 35.2–39.3%, respectively). In scanning electron microscopy studies, all the tested antigens caused tegumental changes in adult worms, with the worst occurring with in vitro TT, such as retracted ventral sucker, an effect on the gynaecophoric canal, and changes to tubercles. In conclusion, in vitro TT, which is cheap to prepare, could be a potential vaccine against S. mansoni.

The northern section of the Caspian Sea and lower reaches of the Zhaiyk (Ural) River is an important fishery for Kazakhstan. In the present study, a total of 1597 individuals of ten fish species were analysed. The fish were caught over three years, from 2018 to 2020. For each species studied – Abramis brama, Alosa saposchnikowii, Atherina boyeri caspia, Carassius gibelio, Chelon auratus, Cyprinus carpio, Leuciscus aspius, Rutilus caspius, Sander marinus and Sander volgensis – between 100 and 200 individuals were examined. A series of generalized linear models (GLMs) were used to examine the association between individual parasite intensity of infection and the Fulton index, age, year the fish was captured, where the fish was captured (northern Caspian or Zhaiyk River) and sex. For each GLM, the best-fitting probability distribution was used –either Poisson, zero-inflated Poisson, negative binomial or zero-inflated negative binomial. For some fish/parasite species, an increased Fulton index was associated with higher intensities of parasite infection, whilst, for others, the Fulton index decreased with the intensity of parasite infection. This was also true of age-related intensity of infection, with some parasites having an increased intensity of infection with age whilst others had a decreased intensity of infection with age. There was also some evidence of variation in intensity of parasite infection between different years when the fish were caught. For some species of fish that are endemic to both the fresh waters of the Zhaiyk River and the low-saline waters of the northern Caspian, there were variations in intensity of parasite infection between the two environments. The best-fitting probability distribution also gave some information about the dynamics of infection. No fish species had a Poisson distribution of parasites, which is consistent with an entirely random infection process, with all fish being potentially exposed. For some parasites, the distribution was a zero-inflated Poisson, which is consistent with either the fish being exposed to parasite infection or not; and, if exposed, infection was a random process. Other parasites had a negative binomial distribution, consistent with the entire fish population being exposed, but the infection process was clumped or there were variations in the susceptibility of infection between fish. Finally, some of the parasites had a zero-inflated negative binomial distribution, which can be interpreted as part of the fish population not being exposed and the remainder of the population being exposed to a clumped or aggregated infection process and/or a variation in individual susceptibility to infection.