Parasite Intensity Research Articles

Parasites Infestation on Cultured Barramundi (Lates calcarifer) and the Impact of Fish Health

Barramundi Lates calcarifer is one of the leading marine aquaculture commodities in Indonesia, therefore fish health should be observed. This study was conducted to determine the type and number of parasites present in barramundi, the prevalence, mean intensity and mean abundance of parasite and the number of leukocytes in each individual, based on the level of infestation. This study used a quantitative descriptive method, using a total of 30 fish with two different sizes of host of ± 20 cm (large) and ±5 cm (small) each as many as 15 individuals. The results showed that size of host samples influenced the number of parasites infested with the prevalence of 40%, while ectoparasite 20%. This may due to differences in the living environment as well as the larger host provides more space to the parasites. The ectoparasites found in barramundi, namely Trichodina sp, Cryptocaryon sp, Benedenia sp, Diplectanum sp and endoparasites, namely Camallanus sp. Ectoparasites Trichodina sp. has the highest mean intensity of 20%. The highest mean abundance on large fish was 3.2 ind/fish on ectoparasite and endoparasites was 0.07 ind/fish. The lowest leukocytes were 179.82 103/μl (19.6 cm) and the highest in sample number three was 218 103/μl (20 cm), all exceeded the normal amount of leucocytes cells for fish was uninfected.

Parasitological investigation of Artemia parthenogenetica: A Cestode case from Ayvalık Saltwork

One of the primary food supplies for the aquaculture sector and wild animal populations, such as flamingos (Phoenicopterus roseus), is Artemia (Artemia parthenogenetica). Along with the rise in cases and reports from different salterns in recent years, the prevalence of Artemia cestode parasitism has also grown. Flamingolepis liguloides eggs are consumed by Artemia and transform into cysticercoids which mature into adult worms in the final host, flamingos. We described the first investigation of cestode parasitism in the natural populations of Artemia parthenogenetica from the Ayvalık saltwork (Balıkesir, Türkiye) in this study. A total of 965 A. parthenogenetica were examined and 320 of them had F. liguloides infection. The overall prevalence was estimated to be 33.2%. Most of the parasites were found in the abdomen and intestinal tract of A. parthenogenetica. Parasitism intensity ranged from 1 to 4 per individual, with a maximum of 4 cysticercoids detected in a single Artemia sample. To understand the influence of parasitism on Artemia populations and the transmission of species, it is important to establish Artemia parasitism in the saltwork. This initial report from the Ayvalık saltwork provides information on the infestation of F. liguloides in Artemia; therefore, the interactions between the saltworks’ species should be investigated in depth.

A survey of ecto and endoparasites of Nile tilapia, Oreochromis niloticus (Linnaeus, 1758) fingerlings in Midmar reservoir, Adwa, northern Ethiopia

ABSTRACT Fishes are hosts to a range of taxonomically diverse parasites. This survey was intended to provide insight into the occurrence, distribution, prevalence, and intensity of parasites infesting the fingerlings of the tilapia, in Tigray. A total of 384 Oreochromis niloticus specimens were collected from Midmar consisting of 227 males and 157 females. External and internal organs were examined for parasite infection. Squash preparation of fish eyes was also examined to reveal the organisms through microscopic examination. The major groups of parasites were trematode, nematodes, protozoa and hirudinea. A total of 3762 genus Diplostomum were recorded affecting the health of 93% of fishes. Contracaecum species was the second most prevalent distributed majorly in the intestine (77.8%), pericardial cavity (19.1%), swim bladder (2.4%), gill (0.2%) and mouth (0.8%). The prevalence and mean intensity of Diplostomum spp., Contracaecum, Myxosporea, Clinostomum spp., Eustrongylides and Leeches was 93%(10.5), 62.2%(5.3), 39.3%(8.3), 2.1%(8.8),1.8%(5.7) and 1.6% (2.5), respectively. The mean temperature, dissolved oxygen, conductivity, and pH of the dam were 24.4°C, 7.55 mg/l, 849.5µs/cm, and 7.5, respectively. Therefore, responsible bodies in fisheries should perform a pre-stock assessment and provide fish farming extension services for optimum production and marketing of fish products with management and production enhancement methods.

Gastrointestinal parasites of the wild ungulates (Mammalia: Cetartiodactyla) in the Hemis National Park, Ladakh, India.

We evaluated the gastrointestinal parasitic prevalence and intensity of wild ungulates in the Hemis National Park of Ladakh by examining their fresh faecal samples. A total of 327 fresh faecal samples from three wild ungulates, blue sheep Pseudois nayaur (n = 127), Ladakh urial Ovis vignei vignei (n = 110), and Himalayan ibex Ibex siberica (n = 90) were collected between June 2021 and May 2022. The techniques of flotation and sedimentation were used to find parasite eggs and oocysts from the faecal samples. Out of 327 samples examined, 165 samples were infected with gastrointestinal parasites making an overall prevalence of 50.45%. Seven parasitic taxa, including one protozoan (Eimeria spp.), five nematodes (Nematodirus spp., Strongyloides spp., Haemonchus sp., Trichuris sp., and Trichostrongylus spp.), and one cestode (Monezia spp.), were found during the current investigation. Mixed infection was reported in 36 (11%) of the total examined samples. The prevalence of gastrointestinal parasites was found to be highest in blue sheep (55.11%), followed by Ladakh urial (49.09%) and Himalayan ibex (45.55%). The highest prevalence was recorded in the summer (64.42%), and the lowest in the winter (33.82%). A significant difference in parasitic prevalence was observed across seasons in each of the three wild ungulate hosts. However, there was no significant difference in the prevalence of parasites between these hosts.

Prevalence of gastrointestinal helminth parasite infections in country chicken from Visakhapatnam district Andhra Pradesh India.

Birds in a free environment carry huge risk of helminth parasite infections affecting the health of poultry and thereby indirectly leading to great economic loss. The present study aimed to evaluate the prevalence, intensity and species diversity of gastrointestinal helminth parasites (GIH) of country chicken (Gallus gallus domesticus) from local chicken markets of Visakhapatnam district, Andhra Pradesh. A total of 300 gastrointestinal tract (GIT) samples were examined from January to December 2021 and the collected parasites were separated, counted, identified and statistically analysed. The overall prevalence of infection was found to be 87% with an intensity of 139.29. The study showed high prevalence with mixed infections (66%), whereas the prevalence with individual groups i.e. cestodes, nematodes and trematodes was found to be 83.00%, 70.33%, and 0.67% respectively. Altogether 10 parasite species were identified viz. Raillietina echinobothrida being the most dominant with a prevalence of 72.67%, followed by Raillietina tetragona (62.00%), Heterakis gallinarum (59.33%), Ascaridia galli (45.33%), Davainea proglottina (43.00%), Amoebotaenia cuneata (42.67%), Raillietina cesticillus (38.33%), Hymenolepis sp. 1 (36.00%), Cotugnia spp. (29.67%) and the least was Hymenolepis sp. 2 (21.00%). In month-wise data, highest prevalence was recorded in July (100%), and the highest seasonal prevalence was recorded in summer (90%), followed by monsoon (87%) and winter (84%). No major significant difference in prevalence was noted between males (88.51%) and females (85.53%). Hosts with high body temperature and low GIT pH levels showed increased prevalence and parasite intensity.

Determinants of spring migration departure dates in a New World sparrow: Weather variables reign supreme.

Numerous factors influence the timing of spring migration in birds, yet the relative importance of intrinsic and extrinsic variables on migration initiation remains unclear. To test for interactions among weather, migration distance, parasitism, and physiology in determining spring departure date, we used the Dark-eyed Junco (Junco hyemalis) as a model migratory species known to harbor diverse and common haemosporidian parasites. Prior to spring migration departure from their wintering grounds in Indiana, USA, we quantified the intrinsic variables of fat, body condition (i.e., mass ~ tarsus residuals), physiological stress (i.e., ratio of heterophils to lymphocytes), cellular immunity (i.e., leukocyte composition and total count), migration distance (i.e., distance to the breeding grounds) using stable isotopes of hydrogen from feathers, and haemosporidian parasite intensity. We then attached nanotags to determine the timing of spring migration departure date using the Motus Wildlife Tracking System. We used additive Cox proportional hazard mixed models to test how risk of spring migratory departure was predicted by the combined intrinsic measures, along with meteorological predictors on the evening of departure (i.e., average wind speed and direction, relative humidity, and temperature). Model comparisons found that the best predictor of spring departure date was average nightly wind direction and a principal component combining relative humidity and temperature. Juncos were more likely to depart for spring migration on nights with largely southwestern winds and on warmer and drier evenings (relative to cooler and more humid evenings). Our results indicate that weather conditions at take-off are more critical to departure decisions than the measured physiological and parasitism variables.

Non-lethal detection of Eubothrium crassum (Cestoda) in farmed Atlantic salmon, Salmo salar, using anal swabs and real-time PCR.

Detection of intestinal parasites in fish typically requires autopsy, resulting in the sacrifice of the fish. Here, we describe a non-lethal method for detecting the tapeworm Eubothrium crassum in fish using anal swabs and real-time PCR detection. Two assays were developed to detect cytochrome oxidase I (COI) mitochondrial DNA and 18S ribosomal DNA sequences of E. crassum, respectively. The assays were tested on swab samples from confirmed pathogen free Atlantic salmon (Salmo salar L.) and on samples from farmed Atlantic salmon, where the presence and intensity of parasites had been established through autopsy. The COI assay was shown to be specific to E. crassum, while the 18S assay also amplified the closely related E. salvelini, a species infecting Arctic charr (Salvelinus alpinus L.) in freshwater. The COI assay detected E. crassum in all field samples regardless of parasite load while the 18S assay failed to detect the parasite in two samples. The results thus demonstrates that this non-lethal approach can effectively detect E. crassum and can be a valuable tool in assessing the prevalence of infection in farmed salmon, aiding in treatment decisions and evaluating treatment effectiveness.

Extreme heat reduces host and parasite performance in a butterfly-parasite interaction.

Environmental temperature fundamentally shapes insect physiology, fitness and interactions with parasites. Differential climate warming effects on host versus parasite biology could exacerbate or inhibit parasite transmission, with far-reaching implications for pollination services, biocontrol and human health. Here, we experimentally test how controlled temperatures influence multiple components of host and parasite fitness in monarch butterflies (Danaus plexippus) and their protozoan parasites Ophryocystis elektroscirrha. Using five constant-temperature treatments spanning 18-34°C, we measured monarch development, survival, size, immune function and parasite infection status and intensity. Monarch size and survival declined sharply at the hottest temperature (34°C), as did infection probability, suggesting that extreme heat decreases both host and parasite performance. The lack of infection at 34°C was not due to greater host immunity or faster host development but could instead reflect the thermal limits of parasite invasion and within-host replication. In the context of ongoing climate change, temperature increases above current thermal maxima could reduce the fitness of both monarchs and their parasites, with lower infection rates potentially balancing negative impacts of extreme heat on future monarch abundance and distribution.

Intestinal helminthiasis, anaemia and associated risk factors in a cross-section of the population of Melong, Littorial Region of Cameroon

Assessment of risk factors of intestinal helminths and anaemia in various geographical regions is important for the development of appropriate control strategies. This study aimed at determining the risk factors associated with intestinal helminths and anaemia in Melong, Cameroon. A total of 325 participants were recruited in this study between September–December 2021. Faecal samples were examined using the formol-ether sedimentation technique while haemoglobin level was measured using a HemoCue spectrometer. Data on demographic and behavioural factors was collected and used to determine the risk factors using a pretested structured questionnaire and analysed using SPSS. The overall prevalence of intestinal helminths was 24.6% (80/325). Helminths recovered from the study included hookworm (16%; 52/325), Schistosoma mansoni (10.8% 35/325) Ascaris lumbricoides (1.9%; 6/325), and Trichuris trichiura (0.6%; 2/325) with 15 participants having multiple infections (4.6%). The geometric mean egg density was 77epg and ranged from 20 to 560 epg of faeces. Males and age group ≤ 5 years had the highest parasite intensity (248epg). The overall prevalence of anaemia was 33.5% (109/325). Anaemia was significantly (p = 0.001) high at 48.8% (39/80) in those infected with intestinal parasites compared to non-infected individuals. Age group of 31–45 years; [3.42(1.05–11.21)] and > 65 years [6.21(1.75–12.47)], poor knowledge [0.41(0.67–6.07)], no regular deworming [0.70(1.76–21.96)], mud floors toilet [6.18(1.61–23.79)], toilets made of sticks [16.5(4.24–64.31)], and participants who did not have stomach/abdominal pains [0.22(0.07–0.67)] were significant predictors of helminth infections. Age group < 15 years [2.58(1.09–6.11)], geophagia [3.69(1.91–9.33)], hookworm infection [3.26(1.49–7.11)], S. mansoni [1.72 (1.16–3.41)] and those with multiple infections [1.76(1.04–2.88)] were identified as risk factors for anaemia. Risk factors identified in this study can be used to improve the control mechanism put in place by the government.

Intensity of Gastrointestinal Parasites and the Associated Risk Factors and Sero-Prevalence of Hemonchosis, among Camels in Egypt

Intensity of Gastrointestinal Parasites and the Associated Risk Factors and Sero-Prevalence of Hemonchosis, among Camels in Egypt

Ecological characterization of fleas on small mammals in natural and disturbed landscapes in the Atlantic Forest ecoregion, Argentina.

To understand the ecoepidemiology of fleas and their interactions with domestic and wild animals, it is necessary to decode the cycles of flea abundance in relation to host species and environmental factors. The province of Misiones, known for its biodiversity and land use changes, provides an excellent study location. We assessed the diversity, prevalence, abundance, and parasitic intensity of fleas collected from 1153 rodents and opossums in various environments in the Upper Paraná Atlantic Forest of Argentina, considering phytogeography and land use. Our findings were consistent with previous studies conducted in humid regions of Argentina and the Atlantic Forest in Brazil. Hosts with high population density exhibited greater flea prevalence and abundance, and widely distributed hosts showed higher flea species richness and diversity. Significant similarities in flea similarity indices among phytogeographic areas, especially in forest. Environments with an anthropogenic gradient exhibited marked dissimilarities, with higher species richness and diversity in less disturbed sites. These parameters may be influenced by the presence of polyxenous Ctenocephalides, Polygenis, and Adoratopsylla fleas co-infesting opossum in urban areas. These findings provide valuable insights into the ecoepidemiology of fleas, their relationships with host species, and the impact of environmental factors in a strategic Atlantic forest ecoregion.

PREVALENCE AND INTENSITY OF ECTOPARASITES IN GOLDFISH (Carassius auratus) AT MAJU MAPAN FARM, MAGELANG REGENCY

Goldfish (C. auratus) at Maju Mapan Farm is one of the leading ornamental fish commodities with a high mortality rate due to disease. For the reason, aim of this research is to know about type, and prevalence and intensity of ectoparasites in goldfish (C. auratus) at Maju Mapan Farm. The method in this research was random sampling for fish sampling 30 fish/pond. Type of parasites, parasites prevalence, parasites intensity were analyzed descriptively and describe of picture, tables, or graph. The result of this observation and identification showed that ectoparasites infected by goldfish at Maju Mapan Farm consisted of 3 type, Trichodina sp., Dactylogyrus sp., and Gyrodactylus sp. The type of ectoparasites that dominated both were Trichodina sp. (96,11%), Dactylogyrus sp. (3,61%) and Gyrodactylus sp. (0,28%). Prevalence of ectoparasites were Trichodina sp. (83,33%), Dactylogyrus sp.(43,33%), Gyrodactylus sp. (6,67%). Intensity of ectoparasites were Trichodina sp. (129 ind/fish), Dactylogyrus sp. (9 ind/fish), Gyrodactylus sp. (4 ind/fish). Trichodina sp. and Gyrodactylus sp.were commonly founded in mucus, while Dactylogyrus sp. only infected goldfish in gill organ. Prevalence dan intensity of ectoparasites were found in goldfish at Maju Mapan Farm had medium stage of infection. Measurement of water quality temperature, pH, and Dissolved Oxygen were showed not optimal result, and ammonia showed above threshold result. The result of measuring water quality parameters were not optimal caused ectoparasites to infect and multiply rapidly in goldfish at Maju Mapan Farm

Investigating the Performance of Efficient and Stable Planer Perovskite Solar Cell with an Effective Inorganic Carrier Transport Layer Using SCAPS-1D Simulation

Organic–inorganic metal halide perovskite (OIMHP) has emerged as a promising material for solar cell application due to their outstanding optoelectronics properties. The perovskite-based solar cell (PSC) demonstrates a significant enhancement in efficiency of more than 20%, with a certified efficiency rating of 23.13%. Considering both the Shockley limit and bandgap, there exists a substantial potential for further efficiency improvement. However, stability remains a significant obstacle in the commercialization of these devices. Compared to organic carrier transport layers (CTLs), inorganic material such as ZnO, TiO2, SnO2, and NiOX offer the advantage of being deposited using atomic layer deposition (ALD), which in turn improves the efficiency and stability of the device. In this study, methylammonium lead iodide (MAPbI3)-based cells with inorganic CTL layers of SnO2 and NiOX are simulated using SCAPS-1D software. The cell structure configuration comprises ITO/SnO2/CH3NH3PbI3/NiOX/Back contact where SnO2 and NiOX act as ETL and HTL, respectively, while ITO is a transparent front-end electrode. Detailed investigation is carried out into the influence of various factors, including MAPbI3 layer size, the thickness of CTLs, operating temperature parasitic resistance, light intensity, bulk defects, and interfacial defects on the performance parameters. We found that the defects in layers and interface junctions greatly influence the performance parameter of the cell, which is eliminated through an ALD deposition approach. The optimum size of the MAPbI3 layer and CTL was found to be 400 nm and 50 nm, respectively. At the optimized configuration, the PSC demonstrates an efficiency of 22.13%, short circuit current (JSC) of 20.93 mA/m2, open circuit voltage (VOC) of 1.32 V, and fill factor (FF) of 70.86%.

Assesment of Hypoderma infestation in a wild population of Cervus elaphus from mountains Atlantic ecosystems in southwestern Europe (Spain)

Hypodermosis in Cervus elaphus was studied in the Riaño Regional Hunting Reserve, Province of León, north-western Spain. One hundred and ten red deer were examined for the presence of warble fly larvae. They were analyzed by PCR analysis of the COI region of mt-DNA and identified as Hypoderma actaeon. The prevalence of larvae was 42.7% with a mean intensity of 12.5 ± 18 (range 1–80) warbles/deer infested. The distribution of larvae in the infested animals showed an aggregated/overdispersed pattern (aggregation index = 25.84), where the larvae are not randomly or uniformly distributed, but strongly aggregated among their hosts. Larvae were found in all three states. First and second-instars were observed mainly in the autumn until the end of winter (November-March) and third-instars in late winter until mid-spring (March–May). The adult animals and the males had a higher prevalence than the young and the females, finding statistically significant differences only according to the sex of the animals. Seasonal variations were observed in the prevalence with the highest number of infested animals in winter and autumn, but not in terms of the mean intensity of parasites. Additionally, we assessed the presence of anti-Hypoderma antibodies in serum by means of indirect ELISA tests, using a crude larval extract (CLE) and a purified fraction the hypodermin C (HyC) obtained from first instars of Spanish isolates of Hypoderma lineatum (cattle). These findings confirm that H. actaeon is widely distributed in northern Spain, and provide new information about its chronobiology in mountainous Atlantic ecosystems from southwestern Europe.

The Geographical Coexist of the Migratory Birds, Ticks, and Nairobi Sheep Disease Virus May Potentially Contribute to the Passive Spreading of Nairobi Sheep Disease

Nairobi sheep disease (NSD) is a hemorrhagic vector-borne disease of small ruminants caused by the Nairobi sheep disease virus (NSDV), also known as Ganjam virus (GV). NSDV and GV refer to the same virus. The NSDV has been identified in East Africa, India, Sri Lanka, and China, and NSDV vector ticks can be carried by birds. There is few research on the mechanism of the global cycle and spillover of NSDV. Based on the prediction of the high probability distribution areas of NSD by the maximum entropy model (MaxEnt), the possible passive transport routes of NSDV vector ticks by migratory birds were simulated for further evaluation. The transmission probability of NSDV vector ticks by migrating birds was calculated using evaluations of the parasitism intensity of ticks on migratory birds at start points, the flying burden of parasitized birds, and the attachment coefficient of ticks on birds during migration. A total of 31 potential transport routes were predicted, which, through interaction with each other, constitute a spreading network for NSDV. Seven species of migratory birds were predicted as intra or interregional carriers. Our study first provides measurable support for estimating the possibility of passive migration of NSDV vector ticks by migratory birds that may be potential carriers of ticks and proposes a transmission mechanism between all known natural foci and potential natural foci. These findings highlight the necessity of cooperation in the management of the NSDV in all known and potential natural foci located in different countries, with the aim of blocking global circulation in a cost-effective way. Furthermore, these findings may also contribute to the prevention of other similar diseases.

EXPLORING A PLANT-DIVERSITY HYPOTHESIS TO EXPLAIN HELMINTH PREVALENCE IN NORTHERN BOBWHITE (COLINUS VIRGINIANUS) IN TEXAS, USA.

Helminths, in particular eyeworms (Oxyspirura petrowi) and cecal worms (Aulonocephalus pennula), may be a factor influencing northern bobwhite (Colinus virginianus) populations in Texas. Previous research has shown a discrepancy in helminth infections between the Rolling Plains and Rio Grande Plains of Texas, US, potentially caused by differences in intermediate host distribution and abundance. We explored an alternative hypothesis centered on plant diversity, given that many plants possess phytochemicals with anthelmintic properties. We predicted that plant diversity would be greater and bobwhite diet more diverse in the Rio Grande Plains than the Rolling Plains, which in turn would potentially expose bobwhites to more plants with anthelmintic properties and therefore result in lower parasite prevalence and intensity. We conducted a literature review of plant diversity, anthelmintic plants, and bobwhite diet in Texas to explore this hypothesis. We also quantified the relationship between helminth prevalence in bobwhites and latitude. We documented trends for higher plant species richness, greater number of anthelmintic plants, and more diverse bobwhite diet in the Rio Grande Plains compared to the Rolling Plains. In addition, we documented a trend for increasing helminth prevalence with latitude for eyeworms but not cecal worms. Our study provides circumstantial evidence supporting the plant-diversity hypothesis and warrants experimental testing.

Contribution to the Knowledge of Gastrointestinal Nematodes in Roe Deer (Capreolus capreolus) from the Province of León, Spain: An Epidemiological and Molecular Study.

A study of gastrointestinal nematodes in roe deer was carried out in the regional hunting reserves of Riaño and Mampodre, Province of León, Spain, to provide information on their prevalence and intensity of infection in relation to the sampling areas, age of the animals, and body weight. Through a regulated necropsy of the animals, all of them harbored gastrointestinal nematodes in their digestive tract, with a mean intensity of parasitism of 638 ± 646.1 nematodes/infected animal. Eleven genera were found and 18 species of gastrointestinal nematodes were identified, three of them polymorphic: Trichostrongylus axei, Trichostrongylus vitrinus, Trichostrongylus capricola, Trichostrongylus colubriformis, Haemonchus contortus, Spiculopteragia spiculoptera/Spiculopteragia mathevossiani, Ostertagia leptospicularis/Ostertagia kolchida, Ostertagia (Grosspiculopteragia) occidentalis, Teladorsagia circumcincta/Teladorsagia trifurcate, Marshallagia marshalli, Nematodirus europaeus, Cooperia oncophora, Capillaria bovis, Oesophagostomum venulosum, and Trichuris ovis. All of them have already been cited in roe deer in Europe, but Marshallagia marshalli, Capillaria bovis, and Ostertagia (Grosspiculopteragia) occidentalis are reported for the first time in Spain in this host. The abomasum was the intestinal section, where the prevalence (98.9%) and mean intensity (x¯ = 370.7 ± 374.4 worms/roe deer; range 3-1762) were significantly higher, but no statistically significant differences were found when comparing the sampling areas and age of animals. The animals with lower body weight had a higher parasite load than those in better physical condition, finding, in this case, statistically significant differences (p = 0.0020). Seven genera and 14 species were identified. In the small intestine, 88% of the animals examined presented gastrointestinal nematodes, with an average intensity of x¯ = 131.7 ± 225.6 parasites/infected animal, ranging between 4-1254 worms. No statistically significant differences were found when the three parameters studied were compared. Four genera and seven species were identified. In the large intestine/cecum, 78.3% of the examined roe deer presented adult worms, with an average intensity of 6.3 ± 5.5 worms/infected animal; range 1-26 worms. Only statistically significant differences were observed when considering the mean intensity of parasitism and the sampling area (p = 0.0093). Two genera and two species were identified. Several of the species found in the study were studied molecularly, and with the sequences obtained compared with those deposited in GenBank, phylogenetic trees were prepared to determine their taxonomic status. Using coprological techniques, the existing correlation in the shedding of gastrointestinal nematode eggs in roe deer was investigated with that of semi-extensive sheep farms in the same study area to verify the existence of cross-transmission of these parasites between wild and domestic animals. The high values found in the studied parameters show that northern Spain is an area of high-intensity infection for roe deer.

Chigger mite (Eutrombicula alfreddugesi) ectoparasitism does not contribute to sex differences in growth rate in eastern fence lizards (Sceloporus undulatus).

Parasitism is nearly ubiquitous in animals and is frequently associated with fitness costs in host organisms, including reduced growth, foraging, and reproduction. In many species, males tend to be more heavily parasitized than females and thus may bear greater costs of parasitism. Sceloporus undulatus is a female-larger, sexually size dimorphic lizard species that is heavily parasitized by chigger mites (Eutrombicula alfreddugesi). In particular, the intensity of mite parasitism is higher in male than in female juveniles during the period of time when sex differences in growth rate lead to the development of sexual size dimorphism (SSD). Sex-biased differences in fitness costs of parasitism have been documented in other species. We investigated whether there are growth costs of mite ectoparasitism, at a time coinciding with sex differences in growth rate and the onset of SSD. If there are sex-biased growth costs of parasitism, then this could suggest a contribution to the development of SSD in S. undulatus. We measured growth and mite loads in two cohorts of unmanipulated, field-active yearlings by conducting descriptive mark-recapture studies during the activity seasons of 2016 and 2019. Yearling males had consistently higher mid-summer mite loads and consistently lower growth rates than females. However, we found that growth rate and body condition were independent of mite load in both sexes. Furthermore, growth rates and mite loads were higher in 2019 than in 2016. Our findings suggest that juveniles of S. undulatus are highly tolerant of chigger mites and that any costs imposed by mites may be at the expense of functions other than growth. We conclude that sex-biased mite ectoparasitism does not contribute to sex differences in growth rate and, therefore, does not contribute to the development of SSD.

A Polarization-Modulated Laser Frequency-Shifted Feedback System Reducing the Parasitic Noise Intensity by About Three Orders of Magnitude

We propose a parasitic noise suppression laser frequency-shifted feedback system based on polarization modulation, which can reduce the parasitic noise intensity by about 30 dB without affecting the signal of interest by applying different polarization modulations to the parasitic noise and the signal to make them converted to system-insensitive and sensitive states, respectively. Therefore, the proposed system can still get correct information which is originally drowned in parasitic noise. Based on the proposed principle, the displacement of the aluminum block 2 m away from the system is successfully recovered. Furthermore, the vibration of an ordinary carton which is 80 m away from the system is demodulated, and the voice signal near the carton is restored according to the vibration information with much better performance than there is no parasitic noise suppression. During the vibration recovery process, the effective response energy as low as 5.5 photons is achieved in each feedback modulation cycle. The successful implementation of the proposed parasitic noise suppression laser frequency-shifted feedback system based on polarization modulation provides a practical anti-interference and sensitive coherent detection method in weak light signals detection.

Characteristics of a sea louse (Caligus clemensi) epizootic in wild Pacific herring (Clupea pallasii)

We characterized a natural sea louse epizootic of Caligus clemensi and the effects of parasitism on Pacific herring Clupea pallasii in Port Angeles Harbor, WA, USA. Infestation prevalence on newly metamorphosed age 0 Pacific herring reached 100% prevalence by mid-August. At this time, the mean louse intensity was 4.6 lice/fish, and a positive correlation occurred between louse intensity and herring body length. The epizootic then waned, with infestation prevalence decreasing to less than 25% and the mean parasite intensity falling below 1 louse. While skin injuries were not detected, motile lice preferentially aggregated around head and anterior dorsal areas. However, louse tropism became evenly distributed over the body as the parasite intensity increased. Louse-induced mortality in herring was negligible in controlled experiments. These results indicate that Caligus clemensi epizootics reach high prevalence, but also fade from mid-summer to early fall. Due to the predominant presence of motile copepod stages, we suggest that the epizootic fades because lice complete their life cycle and dislodge from the host; however, multiple explanations for epidemic fading are possible.