Influence Of Host Sex Research Articles

Ectoparasitic flies of bats (Mammalia: Chiroptera) in urban green areas of northeastern Brazil.

In urban and degraded areas, ectoparasite abundance can be affected by increasing human population density and habitat fragmentation. This study aimed to characterize the ectoparasitic fly community associated with bats in the urban green areas of Sergipe, Brazil. Campaigns were conducted monthly, for two consecutive nights, between September 2019 and February 2021. To capture the bats, ten mist nets were set up inside and at the edge of the habitat fragments. All ectoparasites found were removed from the bats and stored in 70% alcohol. The specificity index, parasitological rates, and level of parasite aggregation were calculated, and the influence of host sex and seasonality on parasitological rates were verified for the most parasitized bats. The collected ectoparasites corresponded to the families Nycteribiidae (S = 1; n = 26) and Streblidae (S = 13; n = 849), with Trichobius costalimai and Medistopoda aranea being the most abundant species. For some interactions, there was an influence of host sex on the prevalence rates, with the highest number of parasites being found on females, which can be explained by their greater susceptibility to parasitism owing to their long stay in roosts. The seasonality influenced the parasitological rates, and opposing patterns (from what was expected) were observed for some interactions; this influence may be due to the biological differences between parasite species. This study provides relevant data on this interaction, especially for urban areas in northeastern Brazil, expanding the number of studies in the State of Sergipe and promoting future studies.

Gleasonian structure in the helminth metacommunity of the opossumDidelphis albiventrisin two extremes of the Atlantic Forest

Didelphis albiventris is the opossum with the largest geographic distribution in Brazil and has a wide spectrum of helminth parasites. This study aimed to describe the species composition and analyse the structure of helminth communities of D. albiventris in two extremes of the Atlantic Forest in Brazil. The influence of host sex, body mass, age, helminth species richness and locality on the abundance and prevalence of the most prevalent helminth species was investigated. Ninety-five per cent of the animals were infected with at least one species. Nine helminth species were found: the nematodes Aspidodera raillieti, Cruzia tentaculata, Trichuris didelphis and Trichuris minuta in the large intestine; Turgida turgida in the stomach; Travassostrongylus orloffi and Viannaia hamata; and the trematodes Brachylaima advena and Rhopalias coronatus in the small intestine. Three helminth morphospecies were also recovered: the nematodes Hoineffia sp. and Viannaia sp. and a cestode in the small intestine. Cruzia tentaculata and V. hamata were the species with the highest mean abundances and intensities, while the most prevalent species were A. raillieti, C. tentaculata, T. turgida and V. hamata, forming the central nucleus of the helminth component community. The analysis of the helminth metacommunity structure indicated a Gleasonian pattern for the total set of infracommunities, corroborating the beta diversity indices, which indicated more species replacement than loss between localities and infracommunities, although at a low level. The results indicated a stronger influence of host attributes than geographical distance on the community structure.

Parasitofauna of Blackchin tilapia Sarotherodon melanotheron (Teleostei: Cichlidae) from Ebrie Lagoon, Côte d’Ivoire

In this study the ecto and endoparasites infecting Sarotherodon melanotheron were investigated in Ebrie Lagoon between February 2019 and November 2019. A total of 108 randomly sampled Sarotherodon melanotheron was procured from fishermen and examined for parasites using standard parasitological methods. The parasites such as Monogenean Cichlidogyrus halinus, C. halli, C. acerbus and Scutogyrus minus), Myxosporea (Myxobolus beninensis, M. diamensis, M. nokouensis and M. sarotherodoni), Copepod (Ergasilus latus and E. sp), Acanthocephalan (Acanthogyrus tilapiae), Nematode (Eustrongylides sp) and the Trematoda (Clinostomum tilapiae and Euclinostomum heterostomum) were recorded. Gill and intestine were respectively the more and the least infected organ by parasites. The intensity of Monogenean, Copepod and Acanthocephalan were positively increased with host body size. In Contrast, the intensity of Myxosporean, Nematode and Trematode did not increase with host standard length. Monogenean and Copepod were more concentrated in male hosts and Myxosporean in female fish. However, no influence of host sex on parasitism level was observed for population of Acanthocephalan, Nematode and Trematode. This could enable the use of appropriate methods to fight against these pathogens, especially in intensive fish farming.

Structure of the Parasite Infracommunity of Hoplobatrachus tigerinus Daudin, 1803 from YSR Kadapa District, Andhra Pradesh, India

Three hundred specimens of Hoplobatrachus tigerinus (Daudin, 1803), 133 females and 167 males, collected in YSR Kadapa district, Andhra Pradesh, India, from 2013 to 2015, were examined for the presence of metazoan parasites. One hundred seventy-two (57.3%) frogs were parasitized by at least one or more metazoan parasite species. Nine species of parasites were collected: 6 digeneans, 1 cestode and 2 nematodes. All the recovered parasites are satellite species with less than 33% prevalence. Digeneans are the most abundant group of parasites accounting for 89.9% of total parasites. Hoplobatrachus tigerinus is a new host record for Paracephalogonimus minutum. Paracephalogonimus minutum is the dominant species followed by Tremiorchis ranarum. The metazoan parasite species of H. tigerinus showed the typical aggregated pattern of distribution of most parasite systems. Only Cosmocercoides variabilis–Oswaldocruzia filiformis (0.23), Paracephalogonimus minutum—Ophiotaenia tigrina (0.13), Diplodiscus amphichrus–Ohiotaenia tigrina (0.13), Cosmocercoides variabilis–Mehraorchis ranarum (0.11) and Ganeo tigrnum–Diplodiscus amphichrus (0.11) showed significant interspecific associations while the other pairs showed very less to no association. There was a very negligible influence of host snout-vent length on the parasitism however; there is no influence of host sex on the parasitic abundance.

Host sexual dimorphism affects the outcome of within-host pathogen competition.

Natural infections often consist of multiple pathogens of the same or different species. When coinfections occur, pathogens compete for access to host resources and fitness is determined by how well a pathogen can reproduce compared to its competitors. Yet not all hosts provide the same resource pool. Males and females, in particular, commonly vary in both their acquisition of resources and investment in immunity, but their ability to modify any competition between different pathogens remains unknown. Using the Daphnia magna-Pasteuria ramosa model system, we exposed male and female hosts to either a single genotype infection or coinfections consisting of two pathogen genotypes of varying levels of virulence. We found that coinfections within females favored the transmission of the more virulent pathogen genotype, whereas coinfections within male hosts resulted in equal transmission of competing pathogen genotypes. This contrast became less pronounced when the least virulent pathogen was able to establish an infection first, suggesting that the influence of host sex is shaped by priority effects. We suggest that sex is a form of host heterogeneity that may influence the evolution of virulence within coinfection contexts and that one sex may be a reservoir for pathogen genetic diversity in nature.

Association of ectoparasites (Diptera and Acari) on bats (Mammalia) in a restinga habitat in northeastern Brazil.

In Brazil, 124 species of ectoparasites of bats are known from the families Streblidae, Nycteribiidae, and Spinturnicidae. This study aimed to characterize the ectoparasites associated with bats in a restinga habitat in Sergipe, northeastern Brazil. Sampling occurred between October 2016 and September 2017 in the Reserva Particular do Patrimônio Natural do Caju through the capture of bats, using 10 mist nets. The ectoparasites collected were stored in 70% alcohol and subsequently identified. For the hosts, the parasitological indexes were calculated and, for the most abundant ones, the influences of the sex of the host and of seasonality on these indexes were evaluated. We collected 430 parasites, of which 77.90% belonged to the Streblidae family. The influence of host sex was observed only in terms of the prevalence between Periglischrus iheringi and Artibeus lituratus, with the highest values observed for females. This may be associated with the highest susceptibility of females to parasitism by the greater permanency in the shelter. In terms of the influence of seasonality, only the interaction between Carollia perspicillata and Trichobius joblingi was affected by temperature, with an increase in prevalence rates and mean intensity during the season with lower temperatures. This relationship may be associated with biological differences among parasites species. The present study identified six new species of ectoparasites and the occurrence of ticks on bats for Sergipe, in addition to registering 11 new bat-ectoparasite associations for the state and two for Brazil, contributing to an increase in our knowledge about bat-ectoparasite interactions.

Is there a Host Sex Bias in Intestinal Nematode Parasitism of the Yellow-necked Mouse (Apodemus Flavicollis) at Obedska Bara Pond, Serbia?

SummaryFifty-one yellow-necked mice from the Obedska bara locality were analysed for the presence of intestinal nematode parasites in order to assert whether there was a host sex bias in infection. Previous research indicated that males would be the more infected sex, either due to the immunosuppressive effect of testosterone or their different allocation of resources towards immune defence. Quantitative infection parameters were compared between host sexes for all nematode species and nematodes in general. In addition, the influence of host sex, age, total body length, body mass and presence of other nematode species on parasite abundance was analysed. No statistically significant differences between males and females were noted for any of the studied quantitative parameters, leading to an absence of sex-biased parasitism in this study.

Ectoparasites of bats (Mammalia: Chiroptera) in Atlantic forest fragments in north-eastern Brazil.

In Brazil, most studies involving parasites of bats (bat flies) treat the mid-west, south-east, and south of the country. This work aimed to characterize the ectoparasites community associated with bats in the Atlantic forest in the state of Sergipe, north-eastern Brazil. Sampling was conducted between January and June 2013 in the Serra de Itabaiana National Park (PNSI) and between November 2013 and June 2015 in the Wildlife Refuge Mata doJunco (RVSMJ). Parasitological indexes were determined, and the influence of host sex and the seasonality in prevalence rates and mean intensity for the most abundant parasites was evaluated. Some 129 parasites were collected in PNSI and 296 in RVSMJ, and 100 and 70.6%, respectively, belong to the family Streblidae. The differences in parasitological rates in Sergipe in relation to other studies may be associated with the environmental characteristics and the composition of the host community. The influence of sex and the seasonal prevalence of Speiseria ambigua and Trichobius joblingi, associated with Carollia perspicillata, may be associated with a lower rate of female captures and low sampling in the dry season. This is a pioneer study in Sergipe that reveals the occurrence of 16 species of streblids and representatives of Acari and Basilia spp., highlighting the need for more studies to increase the wealth and understanding of host-parasite associations in the state.

Body-mass or sex-biased tick parasitism in roe deer (Capreolus capreolus)? A GAMLSS approach

Macroparasites feeding on wildlife hosts follow skewed distributions for which basic statistical approaches are of limited use. To predict Ixodes spp. tick burden on roe deer, we applied Generalized Additive Models for Location, Scale and Shape (GAMLSS) which allow incorporating a variable dispersion. We analysed tick burden of 78 roe deer, sampled in a forest region of Germany over a period of 20 months. Assuming a negative binomial error distribution and controlling for ambient temperature, we analysed whether host sex and body mass affected individual tick burdens. Models for larval and nymphal tick burden included host sex, with male hosts being more heavily infested than female ones. However, the influence of host sex on immature tick burden was associated with wide standard errors (nymphs) or the factor was marginally significant (larvae). Adult tick burden was positively correlated with host body mass. Thus, controlled for host body mass and ambient temperature, there is weak support for sex-biased parasitism in this system. Compared with models which assume linear relationships, GAMLSS provided a better fit. Adding a variable dispersion term improved only one of the four models. Yet, the potential of modelling dispersion as a function of variables appears promising for larger datasets.

Larval migration ofToxocara canisin piglets and transfer of larvae from infected porcine tissue to mice

Visceral larva migrans (VLM), caused by Toxocara canis larvae in humans, animals and birds, is now well documented throughout the world. Seven piglets were infected orally with 5 x 104 embryonated eggs and the migration and distribution of T. canis larvae in the tissues were evaluated. After artificial gastric juice digestion, larval yields at necropsy from different organs and muscles on days 1, 3, 7, 15 and 30 post-infection (DPI) revealed 3.05, 0.97, 0.21, 0.13, 0.05, 0.14% recovery from liver, lungs, heart, kidneys, skeletal muscles and brain tissues respectively, with a total of 2486 (4.97%) recovery from all tissues together. The highest number of larvae 1527 (3.05%) was recovered from the liver throughout the period (1-30 DPI), indicating a special affinity of larvae for the liver. Subsequently five mice were each infected orally with 5 g of infected pig liver and, after necropsy on 10 DPI, 20 +/- 3.62, 17 +/- 5.10, 3 +/- 1.26, 12 +/- 3.92 and 30 +/- 5.69 larvae were recovered from liver, lungs, heart, brain and muscles, respectively. Thus, primarily, the migratory potential and adaptation of T. canis larvae in porcine tissue was examined and, subsequently, their establishment in the second paratenic host, the mouse, has been successful. No influence of host sex on the migratory potential of T. canis larvae was observed. The related pathology caused by migratory larvae and its zoonotic significance through the consumption of raw or undercooked pork has been emphasized.

The helminth parasites of the wild rabbitOryctolagus cuniculusand their effect on host condition in Dunas de Mira, Portugal

The present study focuses on the helminth parasite community of the wild rabbit in a sand dune area in Portugal over a 5-year period. The influence of host sex and year on the composition of the helminth community is assessed, along with the potential effect of the detected helminths on host body condition. The basic structure of the helminth community comprises Mosgovoyia ctenoides, Graphidium strigosum, Trichostrongylus retortaeformis, Nematodiroides zembrae and Passalurus ambiguus. Mean intensities of G. strigosum varied between years. General G. strigosum intensities were also found to vary according to both year and host sex, but not according to the interaction of both factors. When assessing the effect of helminths on rabbit body condition (expressed by the kidney fat index), higher burdens of M. ctenoides, a cestode that presents a relatively large body mass, were found to induce a reduction in rabbit condition.

The Influence of Host Sex on the L3 to L4 Molt of Brugia malayi

Immunocompetent male mice are more susceptible to experimental infection with Brugia spp. than are females. Because permissive male SCID mice (severe combined immunodeficient mice), which lack T and B cells, also possess higher worm burdens, the mechanism is not solely immune mediated. Recovery of fewer adult worms from the female SCID mouse suggests that females do not provide sufficient nutrients for larval growth. This study assessed the potential of the female SCID mouse to support the L3 to L4 molt of Brugia malayi. Unexpectedly, worms grown in females molted at earlier time points of recovery than those harvested from males. This suggests that the early stage of development of B. malayi is delayed in the male murine host. To determine whether the effect of host sex on molting may be similar in humans, worms were cultured in media supplemented with serum from male or female donors. Worms grown in serum obtained from female donors exhibited a significantly higher percentage of complete molts over those cultured with serum from males. Host-derived molecules required for the L3 to L4 molt may be more abundant in the female, perhaps allowing the worms to survive a vulnerable developmental stage in a less permissive environment.

Investigation of Lamproglena pulchella (Nordmann, 1832) on Capoeta trutta and Chondrostoma regium caught in Keban Dam Lake (Elazi?, Turkey)

Summary In this study the eyes, gills, skin, fins and mouths of 216 individuals of two cyprinids species (Capoeta trutta and Chondrostoma regium) caught in the Keban Dam Lake, Elazig, Turkey, were examined for the Lamproglena pulchella parasite; 135 L. pulchella were found on gills of 61 of 216 fish. Body sizes of some of the parasites were measured; prevalence, mean intensity and abundance of L. pulchella were 28.24, 2.21 ± 2.17 and 0.63 ± 1.52, respectively. No influence of host sex on parasite dispersion was observed.

Numbers of lungworm larvae in feces of bighorn sheep: yearly changes, influence of host sex, and effects on host survival

The number of Protostrongylus spp. first-stage larvae in the feces of marked bighorn sheep (Ovis canadensis) was monitored from 1981 to 1988 in southwestern Alberta. Prevalence of infection was 100%. Counts were not correlated with spring precipitation, winter temperature, or number of female sheep in the study population. Percent lamb survival and average counts were correlated only when years affected by the occurrence of a pneumonia epizootic were excluded. In the years before the epizootic, but not afterwards, lambs born to females with high larval counts were less likely to survive to weaning or to 1 year of age than lambs born to females with low counts. Fecal larval counts from the same female in successive years were weakly correlated, and tended to change towards the mean for all females. Counts were affected by host reproduction but not by seasonal migration, and did not affect host survival. Among lambs and yearlings, males had higher counts than females. Lambs had higher counts than adult females. There were no age-specific differences among adult females. The larval count from female lambs was correlated with that from their mother but not that from male lambs. Heart girth of female lambs was correlated with their larval count and that of their mother. I suggest that larval counts are affected by infection intensity and body condition, do not predict pneumonia epizootics, and have limited reliability as an index of herd health.

Influence of host sex on the growth of a human glioblastoma line in athymic mice

Glioblastomas are generally thought to be more common in men than in women. In order to investigate the hormone-dependence of these tumours, we established a human glioblastoma line in athymic mice. The tumour cell type was characterized using immunocytochemical methods. The influence of host sex on growth was evaluated, and hormone receptors were characterized biochemically. The histological features of the initial tumour were conserved in the hetero-transplanted tumours, which consisted of vimentin and GFAP immunoreactive astrocytes. There was a highly significant difference in tumour growth between the two sexes (P less than 0.01). In the male mice, tumours were from 2.5 to 10 times larger than in the females, the latency periods were 30% shorter, and the growth phases were characterized by periods of slow or zero growth. In addition, androgen and oestrogen receptors were detected at low levels (80-270 fmol/g tumour) in the heterotransplanted tumours especially in the males. The fact that the male tumour growth profiles resembled those of some hormone-dependent lines, and that androgen receptors were found preferentially in the male rather than in female tumours would tend to indicate that there is a hormonal influence on the growth of the heterotransplanted tumours. These results provide further evidence for an influence of sex-steroid hormones on the growth of glioblastomas.

Canine filariasis in Salamanca (northwest Spain).

A survey of dogs in four areas of Salamanca province (northwest Spain) was carried out to determine the prevalence of filariids in the canine population. Blood samples from 293 dogs were tested for the presence of microfilariae, using a modification of the Knott technique. For correct identification of filariid species, blood smears associated with the 43 positive Knott tests were histochemically stained for demonstration of the somatic distribution of acid phosphatase activity. The survey revealed the presence in the northwest of Spain of Dirofilaria immitis, D. repens and Dipetalonema reconditum, with an overall prevalence in Salamanca of 12.3%, 0.3% and 2.1% respectively. The greater prevalence of canine heartworm was found in the irrigated area, where 33.3% of the dogs harboured microfilariae. The relationship between the prevalence of D. immitis and mosquito populations, and the influence of host sex and age in this infection, are analysed.

A Quantitative Study of Economically Important Parasites of Walleye Pollock (Theragra chalcogramma) from British Columbian Waters and Effects of Postmortem Handling on Their Abundance in the Musculature

The identity of parasites infecting the musculature and body cavity (including external surfaces of viscera) of walleye pollock (Theragra chalcogramma) collected from two British Columbian localities, their distribution within the host's musculature, and the influence of host sex, length, and method of postmortem handling on parasite prevalence and abundance were determined. Three parasite species were found only in the musculature (Pleistophora sp., pseudophyllidean plerocercoids, and Phocanema decipiens (Krabbe, 1878) larva), two species only in the body cavity (Contracaecum-type larva and Hysterothylacium aduncum (Rudolphi, 1802) larva), and two species in both sites (Anisakis simplex (Rudolphi, 1809) larva and Nybelinia surmenicola Okada in Dollfus, 1929 plerocercoid). In the musculature most A. simplex and N. surmenicola infected the region surrounding the body cavity, with A. simplex being distributed more anteriorly, while most pseudophyllidean plerocercoids occurred in the caudal region. No preferred site of infection was observed for P. decipiens larvae. No statistically significant differences in infection with any of these helminths occurred between right and left body musculature. For pollock of similar lengths, males were more heavily infected than females with larvae of A. simplex and plerocercoids of N. surmenicola. Three species (A. simplex, N. surmenicola, and Pleistophora sp.) occurred with greater prevalence or abundance in larger fish. Storage of eviscerated and round pollock from the Strait of Georgia on ice at 3 °C for periods of up to 7 d did not result in any significant change in the prevalence of infection or abundance of parasites in the musculature. The abundance of these parasites in pollock from Queen Charlotte Sound, northern British Columbia, appears similar to that previously reported for some other areas of the North Pacific Ocean (although not as high as the most heavily infected stocks of the northwest Pacific) while their abundance in fish from the Strait of Georgia, southern British Columbia, appears to be the lowest for any pollock stock examined.Key words: walleye pollock, Theragra chalcogramma; economically important parasites, Pleistophora sp., pseudophyllidean plerocercoids, Nybelinia surmenicola plerocercoid, Phocanema decipiens larva, Contracaecum-type larva, Hysterothylacium aduncum larva, Anisakis simplex larva, British Columbia

Influence of host sex on the growth of human melanoma.

AbstractThe growth of estrogen receptor-positive and -negative human melanoma cells was compared in male and female athymic mice. The growth of all receptor-negative and receptor-positive tumors carried in male mice was significantly greater than receptor-positive tumors in female mice. The receptor-positive tumor growth rate in male mice was inhibited by exogenous estradiol while receptor-negative tumors were not. The results suggest that the favorable influence of sex on the natural history of human melanoma may be restricted to hormonally responsive lesions.

A hamster fibrohemangiosarcoma: influence of host sex on tumor mass.

A fibrohemangiosarcoma was produced in hamsters following the injection of cell inocula. These tumors in pregnant, lactating female hamsters attained a wet tumor weight 4-8 times greater than that noted in either adult male or female hamsters within 6-7 wk.