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Mastomys natalensis and M. coucha are commensal rodent species endemic to Africa. A recent taxonomic revision within Mastomys leaves the parasite–host list of M. natalensis questionable and that of M. coucha incomplete. The current study aimed to develop a better understanding of the ectoparasite diversity associated with the 2 distinct but closely related rodent species and to explore the influence of host and habitat type on ectoparasite infestations. Between 2014 and 2020, 590 rodents were trapped in 3 habitat types (village, agriculture and natural) across a wildlife-human/domestic animal interface. In total 48 epifaunistic species (45 ectoparasitic and 3 predatory) represented by 29 genera from 4 taxonomic groups (fleas, lice, mites and ticks) were recorded. Only 50% of the epifauna were shared between the 2 rodent species, with mites the most speciose taxon in both host species. The abundance of epifaunistic individuals, and also those of mites and fleas, were significantly higher on male M. natalensis, while ticks were significantly higher on reproductively active M. natalensis. For both rodent species, infestations by most epifaunistic taxa (on M. natalensis) and some taxa (on M. coucha) were significantly lower in the village as opposed to the less disturbed agricultural and natural habitat types. The study highlights the importance of host life history, even in closely related rodent species, in shaping parasite profiles and a loss of parasite diversity in more extreme anthropogenic habitats.

Mastomys natalensis and M. coucha are commensal rodent species endemic to Africa. A recent taxonomic revision within Mastomys leaves the parasite–host list of M. natalensis questionable and that of M. coucha incomplete. The current study aimed to develop a better understanding of the ectoparasite diversity associated with the 2 distinct but closely related rodent species and to explore the influence of host and habitat type on ectoparasite infestations. Between 2014 and 2020, 590 rodents were trapped in 3 habitat types (village, agriculture and natural) across a wildlife-human/domestic animal interface. In total 48 epifaunistic species (45 ectoparasitic and 3 predatory) represented by 29 genera from 4 taxonomic groups (fleas, lice, mites and ticks) were recorded. Only 50% of the epifauna were shared between the 2 rodent species, with mites the most speciose taxon in both host species. The abundance of epifaunistic individuals, and also those of mites and fleas, were significantly higher on male M. natalensis , while ticks were significantly higher on reproductively active M. natalensis. For both rodent species, infestations by most epifaunistic taxa (on M. natalensis) and some taxa (on M. coucha) were significantly lower in the village as opposed to the less disturbed agricultural and natural habitat types. The study highlights the importance of host life history, even in closely related rodent species, in shaping parasite profiles and a loss of parasite diversity in more extreme anthropogenic habitats. [ABSTRACT FROM AUTHOR]

Only one species of the genus Paradiplozoon (Akmerov 1974) has so far been recorded in Vimba vimba (Linnaeus, 1758) from Türkiye. This study was planned to improve the recording of the occurrence of diplozoids in V. vimba from a pristine area in a different geographical region. A total of 397 specimens of V. vimba were collected from Lake Köyceğiz by commercial fishermen over a period of one year and examined for the presence of diplozoids. Only one species of Paradiplozoon was found. Following a detailed morphological examination, the species was identified as Paradiplozoon bliccae (Reichenbach-Klinke 1961), which was subsequently confirmed by molecular data. A total of 1025 specimens of P. bliccae infected 185 of the 397 Vimba vimba specimens examined, with prevalence, mean intensity and abundance of 46.6%, 5.5 ± 4 parasites/fish, 2.5, respectively. The highest prevalence and mean abundance were determined in spring, while mean intensity values were higher in summers. Female hosts showed higher prevalence, mean intensity and mean abundance than males.

Endophytic bacteria have a complex coevolutionary relationship with their host macroalgae. Dioecious macroalgae are important producers in marine ecosystems, but there is still a lack of research on how sex influences their endophytic bacteria. In this study, the endophytic bacterial communities in male and female S. thunbergii and their reproductive tissues (receptacles) were compared using culture methods and high-throughput sequencing. The endophytic bacterial communities detected by the two methods were different. Among the 78 isolated strains, the dominant phylum, genus, and species were Bacillota, Alkalihalobacillus, and Alkalihalobacillus algicola, respectively, in the algal bodies, while in the receptacles, they were Bacillota, Vibrio, and Vibrio alginolyticus. However, 24 phyla and 349 genera of endophytic bacteria were identified by high-throughput sequencing, and the dominant phylum and genus were Pseudomonadota and Sva0996_ Marine_ Group, respectively, in both the algal body and the receptacles. The two methods showed similar compositions of endophytic bacterial communities between the samples of different sexes, but the relative abundances of dominant and specific taxa were different. The high-throughput sequencing results showed more clearly that the sex of the host alga had an effect on its endophyte community assembly and a greater effect on the endophytic bacterial community in the receptacles. Moreover, most specific bacteria and predicted functional genes that differed between the samples from the males and females were related to metabolism, suggesting that metabolic differences are the main causes of sex differences in the endophytic bacterial community. Our research is the first to show that host sex contributes to the composition of endophytic bacterial communities in dioecious marine macroalgae. The results enrich the database of endophytic bacteria of dioecious marine macroalgae and pave the way for better understanding the assembly mechanism of the endophytic bacterial community of algae. [ABSTRACT FROM AUTHOR]

Copyright of Ege Journal of Fisheries & Aquatic Sciences (EgeJFAS) / Su Ürünleri Dergisi is the property of Ege Journal of Fisheries & Aquatic Sciences (EgeJFAS) / Su Urunleri Dergisi and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The formation of epiphytic bacterial communities on macroalgae is closely related to host identity, but the effects of tissue location and sex of the host alga on this process, especially the relative contributions of these two factors, have not been studied. Here, the epiphytic bacterial community on three different tissues (tip, receptacle and holdfast) of male and female Sargassum thunbergii in the intertidal zone of Qingdao was investigated using high-throughput sequencing, and the results revealed obvious tissue and sex specificity of the epiphytic bacteria and significant differences from seawater bacterial samples. The biodiversity indexes, specific bacteria, biomarkers, indicator taxa and predicted function of epiphytic bacteria differed significantly among tissues of S. thunbergii and between sexes for the same tissue, confirming that both algal tissue location and sex impacted epiphytic bacterial community assembly on S. thunbergii. Additionally, β-diversity analysis showed that tissue location contributed more than host sex to epiphytic bacterial community structure, and the contributions of these two factors varied among tissues. Sex contributed less to epiphytic bacteria on the holdfast than on the tip and receptacle. Furthermore, the tissue and sex specificity of epiphytic bacteria on S. thunbergii were likely related mainly to host metabolism but also to the interaction between bacteria and algae and adaptability to the environment. This study shed light on the drivers of macroalga-associated bacterial community structure and broaden our understanding of the relationship between macroalgae and their epiphytic bacteria.

Abstract The sex of a host affects the intensity, prevalence, and severity of helminth infection. In many cases, one sex has been found to be more susceptible than the other, with the prevalence and intensity of helminth infections being generally higher among male than female hosts; however, many exceptions exist. This observed sex bias in parasitism results primarily from ecological, behavioural, and physiological differences between males and females. Complex interactions between these influences modulate the risk of infection. Indeed, an interplay among sex hormones, sex chromosomes, the microbiome and the immune system significantly contributes to the generation of sex bias among helminth-infected hosts. However, sex hormones not only can modulate the course of infection but also can be exploited by the parasites, and helminths appear to have developed molecules and pathways for this purpose. Furthermore, host sex may influence the efficacy of anti-helminth vaccines; however, although little data exist regarding this sex-dependent efficacy, host sex is known to influence the response to vaccines. Despite its importance, host sex is frequently overlooked in parasitological studies. This review focuses on the key contributors to sex bias in the case of helminth infection. The precise nature of the mechanisms/factors determining these sex-specific differences generally remains largely unknown, and this represents an obstacle in the development of control methods. There is an urgent need to identify any protective elements that could be targeted in future therapies to provide optimal disease management with regard to host sex. Hence, more research is needed into the impact of host sex on immunity and protection.

The sex of a host affects the intensity, prevalence, and severity of helminth infection. In many cases, one sex has been found to be more susceptible than the other, with the prevalence and intensity of helminth infections being generally higher among male than female hosts; however, many exceptions exist. This observed sex bias in parasitism results primarily from ecological, behavioural, and physiological differences between males and females. Complex interactions between these influences modulate the risk of infection. Indeed, an interplay among sex hormones, sex chromosomes, the microbiome and the immune system significantly contributes to the generation of sex bias among helminth-infected hosts. However, sex hormones not only can modulate the course of infection but also can be exploited by the parasites, and helminths appear to have developed molecules and pathways for this purpose. Furthermore, host sex may influence the efficacy of anti-helminth vaccines; however, although little data exist regarding this sex-dependent efficacy, host sex is known to influence the response to vaccines. Despite its importance, host sex is frequently overlooked in parasitological studies. This review focuses on the key contributors to sex bias in the case of helminth infection. The precise nature of the mechanisms/factors determining these sex-specific differences generally remains largely unknown, and this represents an obstacle in the development of control methods. There is an urgent need to identify any protective elements that could be targeted in future therapies to provide optimal disease management with regard to host sex. Hence, more research is needed into the impact of host sex on immunity and protection. [ABSTRACT FROM AUTHOR]

We investigated the effects of host sex and flea phenology (estimated as periods of high versus low abundance) on individual body size in four fleas of small mammals. Amalaraeus penicilliger and Ctenophthalmus uncinatus are ectoparasites of the bank vole Myodes glareolus, whereas Doratopsylla dasycnema and Palaeopsylla soricis are ectoparasites of the common shrew Sorex araneus. We found significant effects of host sex and phenology on the body size of all flea species, although there was no general trend in the directions of these effects. Larger A. penicilliger were found on female hosts, whereas larger P. soricis were found on male hosts. In the remaining species, larger fleas were collected from male hosts during periods of high abundance (male C. uncinatus and female D. dasycnema) and from female hosts during periods of low abundance (male C. uncinatus). Regarding phenology, larger fleas were recorded during periods of either high (A. penicilliger, C. uncinatus, D. dasycnema) or low (C. uncinatus, P. soricis) abundance, but this depended on flea and/or host sex. We conclude that the directions of the host sex and phenology effects varied between flea species. Furthermore, the direction of the host sex effect was mediated by the effect of phenology and vice versa. [ABSTRACT FROM AUTHOR]

One of North America's major avian migratory pathways occurs along a large anthropogenically modified coastal region of southeastern Virginia, USA. Because hundreds of avian species migrate along the east coast of North America, understanding factors affecting birds and their health is of ecological and conservation interest. Within southeastern Virginia, 14 tick species have been documented, all of which may serve as vectors of vertebrate pathogens. We tested 5 hypotheses to understand how varying levels of urbanization within an urban matrix of a coastal region affected avian parasitism rates. We sampled resident and migratory birds for ticks across an urbanization gradient at 5 permanent and 6 ad hoc sites from August 2012 to August 2014 and determined parasitism rates at the landscape and site scales. At the landscape scale, the proportion of birds parasitized by ticks was reduced at more urbanized sites. Urbanized sites were largely associated with higher water and impervious surfaces in the surrounding area, which may have prevented dispersal of ticks or hosts to isolated urban locations, and lower tree cover, which likely reduced tick survival because of decreased leaf litter. At the site scale, properties associated with being on or near the ground (i.e., foraging guild and age) were the best predictors of tick parasitism. These findings demonstrate that the effects of urbanization are neither uniform nor straightforward. In addition to affecting avian species composition, anthropogenic changes to the landscape are affecting the relationship between avian hosts and their parasites, a finding that has important implications for avian conservation efforts and management practices. © 2019 The Wildlife Society. The proportion of birds parasitized by ticks in coastal southeastern Virginia, USA, decreased with level of urbanization. Water and impervious surface likely limited tick dispersal, whereas tree cover may provide good habitat for ticks. Bird foraging guild and age were the best predictors of whether birds were parasitized at sites where ticks occurred regularly. [ABSTRACT FROM AUTHOR]

During grooming, primates remove harmful ectoparasites, such as ticks and lice, and there is direct evidence for a health benefit of tick removal. Grooming behaviors differ among primates with respect to age and sex. Moreover, the number of ectoparasite may exhibit seasonal variation. Therefore the number of ectoparasites on a host may vary with effects, host age and sex, and season. However, these effects have not been a focus of louse infestation studies of primates. Grooming in Japanese macaques is related to sex and age, with developmental changes in behavior corresponding to the timing of tooth eruption. Moreover, behavioral data for Japanese macaques suggest that lice load may differ with the season. Thus, we examined whether the number of louse eggs varies according to host macaque sex, age, and season, and whether it changes in response to tooth eruption. We counted unhatched and hatched eggs attached to the hair on six 1-cm areas on the left wrist skin of culled macaques, using a stereoscopic microscope. We sampled five winter coats and three summer coats for each age class: infant, juvenile, adolescent, and adult. The number of unhatched and hatched eggs was related to age, but not to sex and season. There were significant differences in the number of unhatched eggs between infants and adults, juveniles and adults, and adolescents and adults. There were also significant differences in the number of hatched eggs between infants and adults, juveniles and adults, adolescents and adults. Tooth eruption did not influence the number of louse eggs. These results suggest that researchers should consider the age of host animals when assessing the relationship between grooming and ectoparasites. [ABSTRACT FROM AUTHOR]

Marek’s disease virus (MDV) is a herpesvirus that induces lymphoma and immunosuppression in chickens. MDV-induced immunosuppression (MDV-IS) is complex and can be divided into two phases: early-MDV-IS associated with cytolytic infection in the lymphoid organs in chickens lacking maternal antibodies against MDV (MAbs) and late-MDV-IS that appears later in the pathogenesis and occurs even in chickens bearing MAbs. We have recently developed a model to reproduce late-MDV-IS under laboratory conditions. This model evaluates late-MDV-IS indirectly by assessing the effect of MDV infection on the efficacy of infectious laryngotracheitis (ILT) vaccines against challenge with ILT virus. In the present study, we have used this model to investigate the role of two factors (MDV pathotype and host sex) on the development of late-MDV-IS. Five MDV strains representing three different pathotypes: virulent (vMDV; 617A, GA), very virulent (vvMDV; Md5), and very virulent plus (vv+MDV; 648A, 686), were evaluated. Only vv+ strains were able to induce late-MDV-IS. An immunosuppression rank (IS-rank) was established based on the ability of MDV to reduce the efficacy of chicken embryo origin vaccine (values go from 0 to 100, with 100 being the highest immunosuppressive ability). The IS-rank of the evaluated MDV strains ranged from 5.97 (GA) to 20.8 (617A) in the vMDV strains, 5.97 to 16.24 in the vvMDV strain Md5, and 39.08 to 68.2 in the vv+ strains 648A and 686. In this study both male and female chickens were equally susceptible to MDV-IS by vv+MDV 686. Our findings suggest that late-MDV-IS is a unique feature of vv+ strains. [ABSTRACT FROM AUTHOR]

Species introductions have altered host and parasite diversity throughout the world. In the case of introduced hosts, population age appears to be a good predictor of parasite richness. Habitat alteration is another variable that may impact host-parasite interactions by affecting the availability of intermediate hosts. The house sparrow (Passer domesticus (Linnaeus, 1758)) is a good model to test these predictions. It was introduced in several parts of the world and can be found across rural-urban gradients. A total of 160 house sparrows from Porto Alegre, state of Rio Grande do Sul, Brazil, were necropsied. Thirty house sparrows (19 %) were parasitized with at least one out of five helminth species (Digenea: Tamerlania inopina Freitas, 1951 and Eumegacetes sp.; Eucestoda: Choanotaenia passerina (Fuhrmann, 1907) Fuhrmann, 1932; Nematoda: Dispharynx nasuta (Rudolphi, 1819) Stiles & Hassall, 1920 and Cardiofilaria pavlovskyi Strom, 1937). Overall, there was no difference in prevalence and intensity of infection of any parasite species, parasite richness and community diversity between adult males and females and adults and juveniles. The number of infected sparrows among seasons, the richness of helminths and the abundance of species were also similar between rural and urban landscapes. Only the prevalence of C. passerina varied seasonally (p=0.0007). A decrease in the number of parasite species from the original range of P. domesticus (13) to its port of entrance in Brazil, the city of Rio de Janeiro (nine), to Porto Alegre (five) is compatible with the hypothesis that host population age is a good predictor of parasite richness.A introdução de espécies tem alterado a diversidade dos parasitos e seus hospedeiros em todo o mundo. No caso dos hospedeiros introduzidos, a idade da população parece ser um bom preditor da riqueza parasitária. A alteração do habitat é outra variável que pode ter impacto sobre as interações parasito-hospedeiro, pois afeta a disponibilidade de hospedeiros intermediários. O pardal (Passer domesticus (Linnaeus, 1758)) é um bom modelo para testar essas predições. Ele foi introduzido em várias partes do mundo e pode ser encontrado ao longo do gradiente urbano-rural. Um total de 160 pardais, provenientes de Porto Alegre, Rio Grande do Sul, Brasil, foram necropsiados, dos quais 19 % (30) estavam parasitados com pelo menos uma das cinco espécies de helmintos encontradas (Digenea: Tamerlania inopina Freitas, 1951 and Eumegacetes sp.; Eucestoda: Choanotaenia passerina (Fuhrmann, 1907) Fuhrmann, 1932; Nematoda: Dispharynx nasuta (Rudolphi, 1819) Stiles & Hassall, 1920 and Cardiofilaria pavlovskyi Strom, 1937). Não houve diferença entre machos adultos e fêmeas adultas e entre adultos e juvenis na prevalência e intensidade de infecção das espécies, na riqueza de parasitos e na diversidade das comunidades de helmintos. Também não houve diferença significativa no número de pardais infectados em cada estação e na riqueza de helmintos e abundância das espécies entre as paisagens rural e urbana. Somente a prevalência de C. passerina variou sazonalmente (p=0,0007). Uma redução no número de espécies de parasitos de P. domesticus desde a sua distribuição original (13) ao seu ponto de entrada no Brasil, a cidade do Rio de Janeiro (nove), até Porto Alegre (cinco), é compatível com a hipótese de que a idade da população hospedeira é um bom preditor da riqueza de parasitos.

I studied the relationship between sex and infestation with ectoparasites in the water rat Scapteromys aquaticus from La Plata river marshland, Argentina. The Relative Density’s Index (RDI) for males was 3.90% (females 3.60%). A total of 2653 ectoparasites were collected on 33 male hosts, and 1945 on 31 females. Ectoparasite specific richness (S) and diversity (H) were S = 14, H = 1.17 on males, and S = 10, H = 1.52 on females. The similarity between male and female rodents according to their ectoparasites was 75.00%. Although no ectoparasite species showed significant mean abundance (MA) differences between host sexes (pSe estudió la interrelación entre el sexo de la rata de agua Scapteromys aquaticus y su infestación por ectoparásitos en la ribera del Río de la Plata, Argentina. El índice de densidad relativa de los machos fue 3.90 % y el de las hembras 3.60%. Se recolectó 2653 ectoparásitos de 33 machos y 1945 de 31 hembras. La riqueza (S) y diversidad específicas (H) de los ectoparásitos fueron S = 14, H = 1.17 en los machos y S = 10, H = 1.52 en las hembras. La similitud entre sexos fue del 75.00%. Si bien ningún ectoparásito en este estudio mostró diferencias significativas en su abundancia media entre los hospedadores de diferente sexo (p

Copyright of Revista de Biologia Marina y Oceanografía (RBMO) is the property of Universidad de Valparaiso, Facultad de Ciencias del Mar and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Females of the parasitoid wasp Dinocampus coccinellae are known to parasitise both male and female coccinellid hosts. It is suggested that female hosts provide more resources for developing wasp larvae because they tend to be larger than male hosts, and female coccinellids have a much greater food intake than males. Thus the wasp's lifetime reproductive success should be increased by ovipositing preferentially in female rather than male hosts when given a choice. Laboratory experiments, using Coccinella septempunctata as a host, show that such a preference does exist. Wasps preferentially oviposit in females, and this preference is not simply a result of the larger mean size of females compared to males. These results corroborate higher rates of prevalence in female compared to male hosts reported previously.

Background: Parasites play pivotal roles in host population dynamics and can have strong ecological impacts on hosts. Knowledge of the effects of parasites on hosts is often limited by the general observation of a fraction of individuals (mostly adults) within a population. The aim of this study was to assess the prevalence of malaria parasites in adult (≥1 year old) and nestling (7-11 day old) Tawny pipits Anthus campestris, to evaluate the influence of the host sex on parasite prevalence in both groups of age, and explore the association between infections and body condition (adults) and growth (nestlings). Methods: Two hundred Tawny pipits (105 adults and 95 nestlings) from one Spanish population were screened for avian malaria parasites (Haemoproteus and Plasmodium) using the polymerase chain reaction (PCR)-based methods. Body condition (body mass against a linear measure of size) was measured in adults and growth rate (daily mass gain) was calculated for nestlings. Results: The overall prevalence of infection was 46%. Sixteen different mitochondrial cytochrome b haplotypes of Plasmodium spp. and one Haemoproteus spp. haplotype were found. Malaria parasites were equally prevalent in nestlings and adults (45 and 46%, respectively). Males were more likely to be infected by parasites than females, and this sex-bias parasitism was evident in both adults and nestlings. Furthermore, a lower daily mass gain during nestling growth in males than in females following infections were found, whereas the effect of infections on body condition of adults was detrimental for females but not for males. Conclusions: Age-specific differences in physiological trade-offs and ecological factors, such as nest predation would explain, at least in part, the observed host sex and age-related patterns in Tawny pipits. [ABSTRACT FROM AUTHOR]

The development of plant-derived cysteine proteinases, such as those in papaya latex, as novel anthelmintics requires that the variables affecting efficacy be fully evaluated. Here, we conducted two experiments, the first to test for any effect of host sex and the second to determine whether the intensity of the worm burden carried by mice would influence efficacy. In both experiments, we used the standard C3H mouse reference strain in which papaya latex supernatant (PLS) consistently shows >80 % reduction in Heligmosomoides bakeri worm burdens, but to broaden the perspective, we also included for comparison mice of other strains that are known to respond more poorly to treatment with papaya latex. Our results confirmed that there is a strong genetic influence affecting efficacy of PLS in removing adult worm burdens. However, there was no effect of host sex on efficacy (C3H and NIH) and no effect of infection intensity (C3H and BALB/c). These results offer optimism that plant-derived cysteine proteinases (CPs), such as these from papaya latex, can function as effective anthelmintics, with neither host sex nor infection intensity presenting further hurdles to impede their development for future medicinal and veterinary usage. [ABSTRACT FROM AUTHOR]

Globally small mammals are important hosts of ectoparasite vectors of pathogens of medical, veterinary and economic importance. Insectivores are currently understudied as hosts of pathogen vectors. However, data are needed on the diversity of such vectors before we can investigate the underlying factors affecting ectoparasite distribution. Abiotic (e.g. temperature and rainfall) and biotic (e.g. host sex) factors have been identified as the main determinants of host–parasite interactions. The present study describes the ectoparasite community of insectivorous eastern rock sengis (Elephantulus myurus) in a nature reserve in the Gauteng province, South Africa, and how it varies with season and host sex. A total of 81 sengis were examined for the presence of ticks, mites, fleas and lice between April 2010 and April 2011. The ectoparasite assemblage comprised 11 groups of tick species, a single mite family, one louse and two flea species, with ticks and mites being the most numerous ectoparasites recovered. The prevalence and/or abundance of two commonly collected ticks (Ixodesspp. andRhipicephalus warburtoni/arnoldi) and chigger varied with season. In addition, female-biased tick burdens were apparent for one ectoparasite species possibly due to reproductive investment. The mechanisms causing the observed patterns should be addressed in future studies. [ABSTRACT FROM PUBLISHER]

Males are usually more prone to parasite infections due to behavioural and ecological patterns as well as genetic and physiological differences between males and females. They have associated aggression, dispersal, and assemblage, which increase the chances of contact with both ecto- and endoparasites. In order to determine the effect of host sex on the establishment and development of Trichinella zimbabwensis, 50 Sprague-Dawley rats aged 6 weeks and weighing between 130-150g were divided into two groups (25 males and 25 females), and orally infected with T. zimbabwensis. On days 5, 10, 15, 20, and 25 post-infection (PI), five randomly selected rats were sacrificed from each group, and the numbers of adult parasites in the intestine as well as larvae in muscles were determined. Results from the study showed a significantly higher amount of Trichinella adults and larvae (P < 0.05) in male than in female Sprague-Dawley rats (four times higher adult worms and two times higher in muscle larvae in males than in females). The mean number of female adult worms was significantly higher (P < 0.05) than male adult worms in male rats on day 5 PI. The mean number of gravid females recovered in male rats on day 5 PI was significantly higher (P < 0.05) than mean number of nongravid females. The female to male ratio of adult worms in male rats increased from 35:1 on day 5 PI to 6:1 on day 10 PI, whilst it was the reverse in female rats. The female to male ratio decreased at day 5 PI from 29:1 to 94:1 at day 10 post-infection. Our study concluded that there were significantly high establishment rates of T. zimbabwensis in the intestines and muscles of male Sprague-Dawley rats than in females, and the sexhormone-linked immunological characteristics could possibly explain these results. [ABSTRACT FROM AUTHOR]

MicroRNA-132 (miR-132) has been demonstrated to affect multiple neuronal functions and its dysregulation is linked to several neurological disorders. We previously showed that acute Toxoplasma gondii infection induces miR-132 expression both in vitro and in vivo. To investigate the impact of chronic infection on miR-132, we infected mice with T. gondii PRU strain and performed assessment 5 months later in six brain regions (cortex, hypothalamus, striatum, cerebellum, olfactory bulb and hippocampus) by qPCR. We found that while acute infection of T. gondii increases the expression of miR-132, chronic infection has the opposite effect. The effect varied amongst different regions of the brain and presented in a sex-dependent manner, with females exhibiting more susceptibility than males. MiR-132 and brain-derived neurotrophic factor (BDNF, an inducer of miR-132) were not co-varies in the brain areas of infected mice. T. gondii DNA/RNA was found in all tested brain regions and a selective tropism towards the hippocampus, based on bradyzoite density, was observed in both males and females. However, the expressions of miR-132 or BDNF were poorly reflected by the density of T. gondii in brain areas. Our findings highlight the importance of investigating the miR-132-mediated neuronal function in mice infected with T. gondii. [ABSTRACT FROM PUBLISHER]

In primate populations, endoparasite species richness and prevalence are associated with host traits such as reproductive and social status, age, sex, host population density, and environmental factors such as humidity. We analyzed the species richness and prevalence of intestinal parasites in two sympatric primate populations, one of Alouatta palliata and one of Ateles geoffroyi, found in a tropical dry forest in Costa Rica. We identified three species of intestinal parasites ( Controrchis sp., Trypanoxyuris sp., and Strongyloides sp.) in these two primate species. We did not find any differences in species richness between the primate species. However, the prevalences of Controrchis sp. and Trypanoxyuris sp. were higher in Alouatta palliata. Similarly, males and lactating females of Alouatta palliata showed higher Controrchis sp. prevalences. We did not observe any differences in parasite richness and prevalence between seasons. Infectious diseases in endangered primate populations must be considered in conservation strategies, especially when defining protected areas. [ABSTRACT FROM AUTHOR]

Adult Rhipicephalus appendiculatus burdens on indigenous cattle in the Southern Province of Zambia were determined. Older animals were infested with significantly higher numbers of ticks than younger animals and male cattle had higher infestations than females of comparable age.

The main goal of this study was to study the acarine parasite, Pimeliaphilus joshuae (Prostigmata: Pterygosomatidae) on various scorpion species from Egypt to determine its prevalence, abundance and intensity in relation to host species, size and sex. A total of 95 Leiurus quinquestriatus, 98 Androctonus australis, 40 A. amoreuxi, 30 Scorpio maurus palmatus and 46 Orthochirus scrobicuosus were examined during August 2009. Prevalence and mean abundance of P. joshuae varied significantly in relation to host species, host size and sex. In L. quinquestriatus, A. australis, and A. amoreuxi, the prevalence was 76.8, 13.3, and 50.0%, whereas the mean abundance was 47.6, 6.7 and 14.3%, respectively. Prevalence and mean abundance of P. joshuae were both positively correlated with host size in L. quinquestriatus and A. australis. We conclude that P. joshuae is found in a wide range of scorpion species exhibiting a low degree of host specificity. Controlled laboratory infection experiments are required to explain why S. m. palmatus and O. scrobicuosus are not susceptible to infestation by P. joshuae. [ABSTRACT FROM AUTHOR]

Sex biases in parasite infestation are known for various host–parasite systems. In most cases, males of higher vertebrates are infested by more parasites than females. The mechanisms behind male-biased infestation may include not only more opportunities for males to encounter parasites and/or better performance of a parasite in male hosts but also active selection of these hosts by a parasite. To test this hypothesis, we studied behavioural responses of the flea Xenopsylla ramesis to males and females of its common rodent host Meriones crassus in Y-maze trials. We asked whether an individual flea is able to discriminate between male and female hosts and choose a male host, and whether previous experience of the fleas (never fed, fed once on a male host, fed once on a female host) affects the choice. Among 385 fleas, 62% made a choice. In general, proportions of female fleas making or not making a choice of a rodent did not differ significantly, whereas the majority of male fleas chose a rodent. Latency of rodent choice was similar between male and female fleas, but was strongly affected by experience: fleas that previously fed on a male rodent or were never fed made their choices significantly faster than fleas previously fed on a female rodent. Among fleas that made a choice, selection of a male versus a female rodent depended on flea sex only. Male fleas chose randomly between a male and a female rodent, whereas female fleas chose a male rodent significantly more often than a female rodent. Our results suggest that male-biased flea infestation may involve active choices of male hosts by fleas. [Copyright &y& Elsevier]

The article discusses a study which investigated the influence of season, year of study, host body size and host sex on the abundance of helminth species parasitic in the frog Scinax nasicus. The study included 273 frogs collected December 2004 and November 2006 in Corrientes City, Province of Corrientes, Argentina. Study authors found that host sex and season have no significant effect on infracommunity parasite species abundance. They added that the occurrence of parasites Opisthoffonimus sp. 2 and Travtrema aff. stenocotyle vary over time, with host body size being the main factor for determining infrapopulation structure of Centrorhynchus sp.

The article presents a study on the predatory blackfin icefish Chaenocephalus aceratus infected with Acanthocephala at the South Orkney Islands and South Shetland Islands. The researchers examined 76 blackfin icefish. They based the comparison between infections of males and females of C. aceratus on the mean abundance of parasites. They found that the dominance of Corynosoma bullosum in females of C. aceratus is a result of weak infections with Corynosoma pseudohamanni and Corynosoma hamanni.

The article presents a study on the helminth fauna of Passer domesticus in the metropolitan region of Porto Alegre in southern Brazil. The researchers estimated the structure of its helminth community and then tested whether the season, age and sex of the host affect helminth composition and richness. They also gathered 160 sparrows using mist nets in 10 different sites in Porto Alegre, which is found in Rio Grande do Sul, Brazil. They concluded that knowledge on the ecology, behavior and environmental requirements of parasites and hosts are important for evaluating the role of landscape in determining the helminth fauna of a species.

We investigated whether a parasite with two routes of transmission responds to the different transmission opportunities offered by male and female hosts by using different transmission strategies in the two sexes. The parasite Ascogregarina culicis, which infects the mosquito Aedes aegypti, can be transmitted as its host’s pupa transforms into an adult or when a female lays its eggs. As the latter transmission route is missing in males, we expected, and found, that the parasite releases a greater proportion of its infectious forms during emergence when it is within a male than when it infects a female. The transmission route, which influences the parasite’s dispersal and the evolution of its virulence, was also affected by the dose of infection and the parasite’s previous transmission route. Our results emphasize the complexity underlying the development of parasites and show their ability to tune their strategy to their environment. [ABSTRACT FROM AUTHOR]

The metazoan parasite fauna composition of the swordfish Xiphias gladius is reported from 145 (72 females and 73 males) specimens caught in Atlantic tropical–equatorial waters during June to July 2006 and August 2007. Seventeen metazoan taxa (two monogeneans, two digeneans, one acanthocephalan, four cestodes, seven nematodes and one copepod) were identified by morphological and genetic methodologies. Among those identified, Anisakis brevispiculata, Anisakis paggiae and the acanthocephalan Bolbosoma vasculosum are new host records. Dominant species were: the anisakid nematode larvae Anisakis physeteris, Anisakis brevispiculata, Hysterothylacium incurvum and Hysterothylacium corrugatum ( s.l.), the adult cestode Fistulicola plicatus, the plerocercoid Hepatoxylon squali and the monogeneans Tristoma integrum and Tristoma coccineum, which showed high prevalences and intensities. The relationship between metazoan parasites and host size and sex was investigated for the first time. No statistically significant correlation was found between host sex and parasite burden. Infection levels with T. integrum and T. coccineum were observed to be significantly negatively correlated to host size. Infection levels by endoparasites observed in X. gladius from Atlantic tropical-equatorial area may be related to host feeding behaviour and the availability of the parasites’ intermediate and final hosts in the area studied. Anisakids of the genus Anisakis, were identified genetically to species level, and were considered to be promising biological tags for the characterization of X. gladius stocks. [ABSTRACT FROM AUTHOR]

Abstract: Schistosoma mansoni is a digenetic trematode and a human parasite responsible for high social and economic impact. Although some authors have studied the effect of host hormones on parasites, not much is known about the effects of host sex on gene expression in Schistosomes. In order to study gene transcripts associated with the host sex, we compared the gene expression profiles of both male and female unisexual adult S. mansoni parasites raised on either male or female hosts, using DNA microarrays. Our results show that host sex caused differential expression of at least 11 genes in female parasites and of 134 in male parasites. Of the differentially expressed genes in female worms, 10 were preferentially expressed in female worms from male mice, while of the 134 differentially expressed genes in male parasites, 79 (59%) were preferentially expressed in worms from female mice. Further investigation of the role of each of those genes will help understand better their importance in the pathogenesis of Schistosomiasis. [Copyright &y& Elsevier]

Abstract: Is the genetic diversity of parasites infecting male and female hosts equal or different? This is the question we address in this paper by studying the neutral genetic variability of the plathyhelminth trematode Schistosoma mansoni within males and females of its natural murine host Rattus rattus in the marshy forest focus of Guadeloupe (French West Indies). Using seven microsatellite markers, we demonstrate that parasites from male hosts are genetically more diversified than parasites from female hosts. Three hypotheses are discussed that could explain this pattern: 1) a host sex-specific duration of cercariae recruitment; 2) a difference in the behaviour of male and female hosts that would lead to the exposure of males to a greater diversity of parasites; and 3) a host sex-biased immunocompetence that would lead to the selection of more genetically diversified individuals in male than in female rats. This finding is the first empirical evidence that each host sex may play different roles in the maintenance of parasite genetic diversity and so in their evolutionary dynamics and epidemiology. [Copyright &y& Elsevier]

Individuals often differ in their ability to transmit disease and identifying key individuals for transmission is a major issue in epidemiology. Male hosts are often thought to be more important than females for parasite transmission and persistence. However, the role of infectious females, particularly the transient immunity provided to offspring through maternal antibodies (MatAbs), has been neglected in discussions about sex-biased infection transmission. We examined the effect of host sex upon infection dynamics of zoonotic Puumala hantavirus (PUUV) in semi-natural, experimental populations of bank vole (Myodes glareolus). Populations were founded with either females or males that were infected with PUUV, whereas the other sex was immunized against PUUV infection. The likelihood of the next generation being infected was lower when the infected founders were females, underlying the putative importance of adult males in PUUV transmission and persistence in host populations. However, we show that this effect probably results from transient immunity that infected females provide to their offspring, rather than any sex-biased transmission efficiency per se. Our study proposes a potential contrasting nature of female and male hosts in the transmission dynamics of hantaviruses.