Infection by parasites or pathogens can have marked physiological impacts on individuals. In birds, infection may affect moult and feather growth, which is an energetically demanding time in the annual cycle. Previous work has suggested a potential link between clinically visible Trichomonas gallinae infection and wing length in turtle doves Streptopelia turtur arriving on breeding grounds. First, T. gallinae infection was characterized in 149 columbids from 5 species, sampled on turtle dove wintering grounds in Senegal during the moulting period, testing whether infection by T. gallinae is linked to moult. Trichomonas gallinae prevalence was 100%, so rather than testing for differences between infected and uninfected birds, we tested for differences in moult progression between birds infected by different T. gallinae strains. Twelve strains of T. gallinae were characterized at the internal transcribed spacer 1 (ITS1)/5.8S/ITS2 region, of which 6 were newly identified within this study. In turtle doves only, evidence for differences in wing length by strain was found, with birds infected by strain Tcl-1 having wings nearly 6 mm longer than those infected with strain GEO. No evidence was found for an effect of strain identity within species on moult progression, but comparisons between infected and uninfected birds should be further investigated in species where prevalence is lower.

Ascaris suum constitutes a major problem in commercial pig farming worldwide. Lower weight gains in infected pigs probably result from impaired nutrient absorption. This study investigated intestinal nutrient transport in 4 groups of 6 pigs each, which were inoculated with 30 living adult A. suum, or antigen fractions consisting of (1) total excretory–secretory (ES) antigens of adult worms, (2) ES antigens secreted exclusively from the parasites' body surface (trans-cuticular ES) and (3) cuticular somatic antigens of A. suum, compared to placebo-treated controls. Three days after inoculation into the gastrointestinal tract, glucose, alanine and glycyl-l-glutamine transport was measured in the duodenum, jejunum and ileum using Ussing chambers. Transcription of relevant genes [sodium glucose cotransporter 1 (SGLT1), glucose transporter 1 (GLUT1), GLUT2, hypoxia-inducible factor 1-alpha (Hif1α), interleukin-4 (IL-4), IL-13, signal transducer and activator of transcription 6 (STAT6), peptide transporter 1 (PepT1)] and expression of transport proteins [SGLT1, phosphorylated SGLT1, GLUT2, Na+/K+-ATPase, amino acid transporter A (ASCT1), PepT1] were studied. Although no significant functional changes were noted after exposure to adult A. suum, a significant downregulation of jejunal GLUT1, STAT6, Hif1α and PepT1 transcription as well as ileal GLUT2 and PepT1 expression indicates a negative impact of infection on transport physiology. Therefore, the exposure period of 3 days may have been insufficient for functional alterations to become apparent. In contrast, A. suum antigens mainly induced an upregulation of transport processes and an increase in transcription of relevant genes in the duodenum and jejunum, possibly as a compensatory reaction after a transient downregulation. In the ileum, a consistent pattern of downregulation was observed in all inoculated groups, in line with the hypothesis of impaired nutrient transport.

The mere presence of predators or parasites can negatively impact the fitness of prey or hosts. Exposure to predators during an organism's development can have deleterious effects on juvenile survival and the subsequent adult stage. Currently, it is unknown if parasites have analogous impacts on host larval stages and whether these effects carry over into other subsequent life stages. However, parasites may be exerting widespread yet underestimated non-consumptive effects (NCEs). We tested if Drosophila nigrospiracula larvae avoid pupating near mite cues (caged Macrocheles subbadius) in arena experiments, and measured the rate of pupation in arenas with mites and arenas without mites. Larvae disproportionately pupated on the side of arenas that lacked mite cues. Furthermore, fewer larvae successfully pupated in arenas containing mites cues compared to arenas without mite cues. We found that ectoparasitic mites exert NCEs on Drosophila larvae, even though the larval stage is not susceptible to infection. We discuss these results in the context of parasite impacts on host population growth in an infectious world.

Larval stages of the widely distributed digenean species Proctoeces maculatus (Looss, 1901) were reported 40 years ago from South Africa in the common octopus, Octopus vulgaris Cuvier (Octopodidae). However, the absence of adult specimens and molecular data from this region has hindered a comprehensive understanding of its distribution. In this study, we collected three species of intertidal and near-shore marine fishes [Clinus superciliosus (L.) (Clinidae), Diplodus capensis (Smith) (Sparidae) and Sparodon durbanensis (Castelnau) (Sparidae)] along the South African coast and discovered adult specimens of P. maculatus at five localities. By employing a combination of morphological and molecular techniques, including 28S rDNA, 18S rDNA and COI mtDNA analyses, the first report of adult P. maculatus from South Africa is presented. The findings encompass a comprehensive morphological description and molecular data, illuminating the true distribution of this species in the region.

Avian endoparasites play important roles in conservation, biodiversity and host evolution. Currently, little is known about the epidemiology of intestinal helminths and protozoans infecting wild birds of Britain and Ireland. This study aimed to determine the rates of parasite prevalence, abundance and infection intensity in wild passerines. Fecal samples (n = 755) from 18 bird families were collected from 13 sites across England, Wales and Ireland from March 2020 to June 2021. A conventional sodium nitrate flotation method allowed morphological identification and abundance estimation of eggs/oocysts. Associations with host family and age were examined alongside spatiotemporal and ecological factors using Bayesian phylogenetically controlled models. Parasites were detected in 20.0% of samples, with corvids and finches having the highest prevalences and intensities, respectively. Syngamus (33%) and Isospora (32%) were the most prevalent genera observed. Parasite prevalence and abundance differed amongst avian families and seasons, while infection intensity varied between families and regions. Prevalence was affected by diet diversity, while abundance differed by host age and habitat diversity. Infection intensity was higher in birds using a wider range of habitats, and doubled in areas with feeders present. The elucidation of these patterns will increase the understanding of parasite fauna in British and Irish birds.

Cystic echinococcosis (CE) is considered the most severe parasitic disease that ever affected the human population in Iceland. Before the start of eradication campaign in the 1860s, Iceland was a country with very high prevalence of human CE, with approximately every fifth person infected. Eradication of CE from Iceland by 1979 was a huge success story and served as a leading example for other countries on how to combat such a severe One Health problem. However, there is no genetic information on Echinococcus parasites before eradication. Here, we reveal the genetic identity for one of the last Echinococcus isolates in Iceland, obtained from a sheep 46 years ago (1977). We sequenced a large portion of the mitochondrial genome (8141 bp) and identified the isolate as Echinococcus granulosus sensu stricto genotype G1. As G1 is known to be highly infective genotype to humans, it may partly explain why such a large proportion of human population in Iceland was infected at a time . The study demonstrates that decades-old samples hold significant potential to uncover genetic identities of parasites in the past.

The distribution of parasites is shaped by a variety of factors, among which are the migratory movements of their hosts. Israel has a unique position to migratory routes of several bird species leaving Europe to winter in Africa, however, detailed studies on the parasite fauna of birds from this area are scarce. Our study investigates occurrence and distribution of sibling species among Contracaecum rudolphii complex in Phalacrocorax carbo sinensis from Italy and Israel, to acquire further information on the geographical range of these species to gain deeper knowledge on the ecology of these parasites and their bird host. A total of 2383 Contracaecum were collected from the gastric mucosa of 28 great cormorants (18 from Israel and 10 from Italy). A subsample was processed for morphological analyses in light and scanning electron microscopy (SEM), and for molecular analyses through amplification and sequencing of the ITS rDNA and the cox2 mtDNA, and through PCR-RFLP. All the 683 Contracaecum subjected to molecular identification belonged to C. rudolphii s.l., (300 C. rudolphii A and 383 C. rudolphii B). SEM micrographs provided, for the first time, details of taxonomic structures in male specimens from both sibling species, and the first SEM characterization of C. rudolphii B. This work presents the first data on the occurrence of sibling species of C. rudolphii in Israel and provides additional information on the distribution of C. rudolphii A and B in Italy, confirming the high prevalence and intensity of infection observed in Ph. carbo sinensis from other Italian areas.

Parasites and parasitologists have always lived together in good and bad luck in a sort of forced marriage. In recent times bad luck certainly prevailed, because of increasing man-made emergencies such as wars, chemical disasters, but also because of natural disasters, amplified by climate change, that condition more and more parasite–host equilibrium. The symposium at the National Congress of the Italian Society for Parasitology, was a first occasion for Italian parasitologists to reason about ‘disaster parasitology’ and researchers’ responsibilities. Extreme weather events and their impacts on parasites’ epidemiology are illustrated, comparing disasters that recently occurred in Italy with literature data. In particular, the Sardinian Island was hit subsequently by fires and floods exacerbating the effects on ecosystems and parasite–host-relationships. Examples of Cryptosporidium outbreaks in man and Fasciola hepatica infections in various hosts after heavy rains are reviewed and effects of droughts on pasture borne parasites, such as gastro-intestinal nematodes of ruminants are discussed. Heavy rains may also cause dissemination of toxic substances released accidentally from chemical plants as happened e.g. in Milan province (IT) after the dioxin hazard. The overlapping effects of strictly man-made disasters with climate change dependent extreme weather events is further challenging the understanding of what are the consequences of disasters on ecosystems and parasite epidemiology.

GIS applications combined with AI programs may help to face the complex challenges, allowing the collection and analysis of spatial/temporal data at whatever level desired. Examples illustrated in the article suggest their employment also in a more systematic, prevention-oriented manner.

Parasites are key components of the biosphere not only due to their huge diversity, but also because they exert important influences on ecological processes. Nevertheless, we lack an understanding of the biogeographical patterns of parasite diversity. Here, we tap into the potential of biodiversity collections for understanding parasite biogeography. We assess species richness of supracommunities of helminth parasites infecting mammal assemblages in the Nearctic, and describe its relation to latitude, climate, host diversity, and land area. We compiled data from parasitology collections and assessed parasite diversity in Nearctic ecoregions for the entire parasite supracommunity of mammals in each ecoregion, as well as separately from carnivores and rodents to explore the effect of host taxonomic resolution on observed patterns. For carnivores, we found evidence of a negative latitudinal gradient, while parasites of rodents displayed no clear pattern. We found that parasite diversity was positively correlated with mean annual temperature and negatively correlated with seasonal precipitation. Parasite richness shows a diversity peak at intermediate host richness values and in carnivores correlates with temperature and seasonal precipitation. Rodent parasite diversity did not correlate with explored factors. Other researchers are encouraged to use parasitology collections to continue exploring patterns of parasite biogeography and macroecology.

Trypanosoma cruzi, the aetiological agent of Chagas disease, exists as an anthropozoonosis in Louisiana. Raccoons are an important reservoir, as they demonstrate high prevalence and maintain high parasitaemia longer than other mammals. Given the complex nature of parasite transmission networks and importance of raccoons as reservoirs that move between sylvatic and domestic environments, detailing the genetic diversity of T. cruzi in raccoons is crucial to assess risk to human health. Using a next-generation sequencing approach targeting the mini-exon, parasite diversity was assessed in 2 metropolitan areas of Louisiana. Sequences were analysed along with those previously identified in other mammals and vectors to determine if any association exists between ecoregion and parasite diversity. Parasites were identified from discrete typing units (DTUs) TcI, TcII, TcIV, TcV and TcVI. DTUs TcII, TcV and TcVI are previously unreported in raccoons in the United States (US). TcI was the most abundant DTU, comprising nearly 80% of all sequences. All but 1 raccoon harboured multiple haplotypes, some demonstrating mixed infections of different DTUs. Furthermore, there is significant association between DTU distribution and level III ecoregion in Louisiana. Finally, while certain sequences were distributed across multiple tissues, others appeared to have tissue-specific tropism. Taken together, these findings indicate that ongoing surveillance of T. cruzi in the US should be undertaken across ecoregions to fully assess risk to human health. Given potential connections between parasite diversity and clinical outcomes, deep sequencing technologies are crucial and interventions targeting raccoons may prove useful in mitigating human health risk.

Invertebrate host–parasite associations are one of the keystones in order to understand vector-borne diseases. The study of these specific interactions provides information not only about how the vector is affected by the parasite at the gene-expression level, but might also reveal mosquito strategies for blocking the transmission of the parasites. A very well-known vector for human malaria is Anopheles gambiae. This mosquito species has been the main focus for genomics studies determining essential key genes and pathways over the course of a malaria infection. However, to-date there is an important knowledge gap concerning other non-mammophilic mosquito species, for example some species from the Culex genera which may transmit avian malaria but also zoonotic pathogens such as West Nile virus. From an evolutionary perspective, these 2 mosquito genera diverged 170 million years ago, hence allowing studies in both species determining evolutionary conserved genes essential during malaria infections, which in turn might help to find key genes for blocking malaria cycle inside the mosquito. Here, we extensively review the current knowledge on key genes and pathways expressed in Anopheles over the course of malaria infections and highlight the importance of conducting genomic investigations for detecting pathways in Culex mosquitoes linked to infection of avian malaria. By pooling this information, we underline the need to increase genomic studies in mosquito–parasite associations, such as the one in Culex–Plasmodium, that can provide a better understanding of the infection dynamics in wildlife and reduce the negative impact on ecosystems.

In this study, the mitochondrial genome of Eulaelaps silvestris, which parasitizes Apodemus chevrieri, was sequenced and assembled to fill the gap in understanding the molecular evolution of the genus Eulaelaps. The E. silvestris mitochondrial genome is a double-stranded DNA molecule with a length of 14 882 bp, with a distinct AT preference for base composition and a notably higher AT content than GC content. The arrangement between genes is relatively compact, with a total of 10 gene intergenic regions and 12 gene overlap regions. All protein-coding genes had a typical ATN initiation codon, and only 2 protein-coding genes had an incomplete termination codon T. Out of the 13 protein-coding genes, the 5 most frequently used codons ended in A/U, with only 1 codon ending in G/C had an relative synonymous codon usage value >1. Except for trnS1 and trnS2, which lacked the D arm, all other tRNAs were able to form a typical cloverleaf structure; and there were a total of 38 mismatches in the folding process of tRNA genes. Unlike the gene arrangement order of the arthropod hypothetical ancestor, the E. silvestris mitochondrial genome underwent fewer rearrangements, mainly near tRNA genes and control regions. Both the maximum likelihood tree and the Bayesian tree showed that the family Haemogamasidae is most closely related to the family Dermanyssidae. The results not only provide a theoretical basis for studying the phylogenetic relationships of the genus Eulaelaps, but also provide molecular evidence that the family Haemogamasidae does not belong to the subfamily Laelapidae.

Epilepsy, a chronic disease of the central nervous system, is highly prevalent in malaria-endemic regions. Therefore, several studies have evaluated the associations between malaria infection and epilepsy development. A meta-analysis of observational studies published from inception to 10 May 2022 has been conducted to synthesize and pool the existing data on this topic. The relevant publications were systematically searched in PubMed/Medline, Scopus, Embase and Web of Science database collections. A random-effects meta-analysis model (REM) was utilized to generate the pooled odds ratio (OR) at 95% confidence intervals (CIs). The between-studies heterogeneity was assessed with I2, as well as several subgroups, meta-regression and sensitivity analysis were performed to identify the source of heterogeneity. Overall, 17 eligible studies containing 6285 cases and 13 909 healthy controls were included. The REM showed a significant positive association between malaria infection and epilepsy development (OR 2.36; 95% CI 1.44–3.88). In subgroup analyses, significant positive associations were observed in studies that: epilepsy was the outcome in the follow-up of patients with cerebral malaria (OR 7.10; 95% CI 3.50–14.38); used blood smear to diagnose malaria (OR 4.80; 95% CI 2.36–9.77); included only children (OR 3.92; 95% CI 1.81–8.50); published before 2010 (OR 6.39; 95% CI 4.25–9.62). Our findings indicated that patients with malaria, especially those with cerebral malaria, are at a high risk of epilepsy development; however, further well-designed and controlled studies are needed to verify the strength of the association.

Cercarial dermatitis (‘swimmer's itch’; SI), characterized by small itchy bumps caused by schistosome parasites of birds and mammals, is a common problem in Michigan. Research on avian schistosomes began nearly 100 years ago in Michigan inland lakes, yet scientists are still uncovering basic biological information including the identification of local snail and parasite species that cause SI. Previous research primarily focused on lakes in the northern half of Michigan's lower peninsula, although SI occurs throughout the state. We surveyed snails and snail-borne trematodes in lakes across Michigan's lower peninsula and used quantitative polymerase chain reaction analysis of filtered water samples to identify parasites to the species level, including a recently discovered parasite species that uses the snail Planorbella (Helisoma) trivolvis as its intermediate host. Most SI mitigation efforts have focused on a parasite species hosted by the snail Lymnaea catescopium ( = Stagnicola emarginata); however, lymnaeid snails and their associated schistosome species were largely restricted to northern lakes. In contrast, P. trivolvis and its associated parasite species were common in both northern and southern Michigan lakes. A third schistosome species associated with physid snails was also present at low levels in both northern and southern lakes. These results indicate that the recently discovered parasite species and its planorbid snail intermediate host may be more important drivers of Michigan SI than previously thought, possibly due to increased definitive host abundance in recent decades. These results have potentially important implications for SI mitigation and control efforts.

Echinolaelaps echidninus is a gamasid mite that is of medical and veterinary significance as parasites and vectors of disease agents, which can carry pathogens of zoonosis such as Rickettsia tsutsugamushi, Rickettsia Q fever, Rickettsia mooseri, Rickettsia pox pathogens, Corynebacterium pseudotuberculosis and Leptospira. At present, only single mitochondrial genes have been analysed for E. echidninus in the world, and no complete mitochondrial genome has been reported. However, information carried by a single gene is limited. Therefore, the complete mitochondrial genome of E. echidninus was determined for the first time by Illumina Hiseq X-Ten platform in this study. The mitochondrial genome is 15 736 bp in length and contains 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes and a control region of 1561 bp in length. Codon analysis of 13 protein-coding genes revealed that UUU, UUA, AUU, AUA and AAU were the most frequently used, while cox2 had the fastest evolutionary rate and cob the slowest. Comparative analysis of genome structure and breakpoint distances of the mitochondrial genomes of 23 species in 17 genera from 10 families of Gamasida deposited in GenBank revealed a novel gene arrangement type of the E. echidninus mitochondrial genome, and different degrees of rearrangement among different taxa of Gamasida. Phylogenetic analyses of Gamasida were performed using the maximum likelihood and Bayesian inference methods. Echinolaelaps echidninus was clustered with Dermanyssoidea and formed a more supportive sister group with Varroa destructor. This study provides novel insights into rearrangement patterns and evolution of mitochondrial genomes of Gamasida.

Larval trombiculid (chigger) mites are common ectoparasites of terrestrial vertebrates including humans, causing itching and skin inflammation known as trombiculiasis. Investigation of their diversity, distribution and seasonal abundance is therefore important from a veterinary and public health point of view. Although researchers have paid increased attention to these parasites in recent years, there is still little ecological data available on chiggers associated with birds inhabiting different types of habitats such as wetlands, for example. In 2021, we investigated the mite fauna in a specialist reedbed passerine, the bearded tit (Panurus biarmicus), and their effects on this host in the south-west Slovakia, Central Europe. A total of 1134 larvae of 1 mite species Blankaartia acuscutellaris were found in 99 out of 267 examined bearded tits. Juveniles were more infested than adult birds, but no differences were found between sexes. The larvae of mites first appeared on the host during the second half of June and peaked in the second half of July. After that, their numbers decreased gradually until October. Despite the relatively high prevalence and intensity of mite infestation in the bearded tit, no differences in body condition between infested and uninfested birds suggest that infestation by B. acuscutellaris may not have serious negative effects on the host health. Bearded tits can therefore be a reliable indicator of the presence of the chigger mites in wetland habitats.

The Argentine shortfin squid, Illex argentinus, inhabits in the southwest Atlantic; it is a semelparous species which grows rapidly along its 1 year lifespan. The identification of its stocks is critical for sustainable fishery exploitation. Parasites have been used as biological indicators in a lower number of studies dealing with squids, therefore a validation of this methodology is necessary. The intra- and inter-cohort variability of parasite assemblages in the summer-spawning stock of I. argentinus was analysed to assess their value as indicators of stock structure. Four squid samples from the continental shelf of central Patagonia, corresponding to 3 consecutive cohorts, were examined for metazoan parasites. Results evidenced heterogeneity in terms of parasite assemblage composition and structure, dominated by short-lived gastrointestinal parasites, with a strong influence of host size, but no effect of squid sex. These changes are related to their recent habitats and diets, which change with ontogeny and migrations, clouding any interpretation of patterns when samples spatially or temporally separated are compared. Many squid species share these characteristics; therefore, it is recommended that the use of parasites as biological tags should be restricted to simultaneous sampling, while size or age must be considered for deriving proper conclusions.