Extracellular vesicles are membrane-bound particles released by virtually all known cells, from bacteria to human neurons. They range from small exosomes, roughly 30 to 150 nanometers in diameter and born inside multivesicular bodies, to larger microvesicles that bud directly from the plasma membrane. Far from being cellular debris, these particles act as couriers: they carry proteins, lipids, and nucleic acids between cells, and their cargo can reprogram the recipient’s behavior. In the context of T. gondii, the review frames EVs as an extension of the parasite’s secretory arsenal, a parallel channel of communication that operates alongside, and sometimes in concert with, the classical apical secretion systems that parasitologists have studied for decades.

The technical foundations of this field rest on a growing toolkit for isolating and characterizing vesicles. The review catalogs the methods that have defined the state of the art: ultracentrifugation and size-exclusion chromatography for separation, nanoparticle tracking analysis and dynamic light scattering for sizing vesicle populations, transmission and scanning electron microscopy for direct visualization, and Western blotting, mass spectrometry, and immunocytochemistry for identifying the proteins that vesicles carry. Lipid composition is probed with techniques such as Fourier transform infrared spectroscopy, revealing envelopes enriched in phosphatidylcholine, phosphatidylethanolamine, sphingomyelins, ceramides, and triacylglycerols. Each method carries its own biases and limitations, and the authors emphasize that careful, standardized characterization is essential if the field is to distinguish genuine biological signaling from artifacts of preparation.

Biogenesis is where the story becomes mechanistically rich. Parasite-derived vesicles appear to draw on conserved eukaryotic machinery, including the endosomal sorting complexes required for transport, the ESCRT apparatus, and SNARE-mediated membrane fusion, pathways that T. gondii shares with its hosts despite being separated by more than a billion years of evolution. Multivesicular bodies within the parasite can package cargo into intraluminal vesicles that are released when these compartments fuse with the parasite’s surface. The result is a population of vesicles whose membrane composition and internal cargo reflect the physiology of the cell that made them, whether that cell is the parasite itself or the host cell it has commandeered. This dual origin is one of the review’s central conceptual points: the vesicles circulating in the blood or tissues of an infected animal are a mixture, some born of the parasite and some of the infected host, and both populations carry messages.

The cargo of T. gondii-associated vesicles reads like an inventory of the parasite’s most important virulence tools. Proteomic analyses have detected proteins associated with invasion and intracellular survival, including members of the rhoptry protein, rhoptry neck protein, microneme protein, dense granule protein, and surface antigen families, the very molecules the parasite uses to attach to, penetrate, and remodel host cells. Alongside these proteins travel regulatory microRNAs, small RNA molecules capable of silencing host genes, and bioactive lipids that can themselves trigger signaling cascades. The packaging of such a diverse molecular repertoire into a single nanoscale delivery vehicle positions EVs, in the authors’ framing, as multilayered effectors, capable of acting simultaneously on protein receptors, gene expression, and membrane biochemistry in the cells they encounter.

Functionally, the review organizes the evidence around three themes: infection priming, immune modulation, and neural reprogramming. Infection priming refers to the observation that vesicles released by the parasite or by infected cells can prepare host tissues for invasion, altering the local environment before the parasite itself arrives. Immune modulation is the better-documented phenomenon: vesicle cargo can shift the balance of inflammatory signaling, dampening the Th1-type responses that would otherwise clear the parasite and encouraging states of immune tolerance that permit long-term persistence. Because T. gondii establishes lifelong infection precisely by walking this immunological tightrope, vesicle-mediated modulation offers a compelling explanation for how the parasite sustains its delicate equilibrium with the host immune system over decades.

The neural dimension is perhaps the most provocative. T. gondii is unusual among parasites in its ability to form tissue cysts in the brain, and behavioral changes in infected rodents, including a curious loss of aversion to cat odor, have fascinated researchers for years. The review highlights evidence that vesicles can influence neural cells, carrying microRNAs and other regulatory molecules capable of reshaping gene expression in neurons and glia. The authors are careful to frame this as an emerging area: the mechanistic chain from vesicle uptake to altered neural circuitry remains incompletely mapped, and the field has not yet demonstrated a complete causal pathway from a specific vesicle cargo to a specific behavioral change. Even so, the possibility that a parasite can package gene-regulatory messages into vesicles that cross into neural tissue opens a research agenda with implications far beyond toxoplasmosis.

What elevates the review beyond a catalog of mechanisms is its translational argument. The same vesicles that mediate immune evasion could serve as diagnostic biomarkers: because their cargo reflects the presence and activity of the parasite, detecting parasite-associated vesicles or their molecular signatures in patient samples, through methods such as enzyme-linked immunosorbent assays, could offer a window into infection status that conventional serology cannot provide. As vaccine platforms, vesicles present a natural display of parasite antigens in a membrane context that mimics infection, potentially stimulating immunity without requiring live organisms. And as therapeutic delivery vehicles, they offer a biocompatible nanoscale capsule that could, in principle, be engineered to carry drugs or immunomodulatory molecules across biological barriers that defeat conventional formulations, including the blood-brain barrier that shields the parasite’s chronic cysts from most treatments.

The authors also confront the field’s growing pains honestly. EV research across all of biology suffers from reproducibility challenges: isolation methods yield heterogeneous populations, quantification is inconsistent between laboratories, and distinguishing parasite-derived vesicles from host-derived ones in infected samples is technically demanding. The review’s emphasis on standardized characterization, combining orthogonal techniques such as electron microscopy, nanoparticle tracking, and proteomic validation, reflects a maturing discipline recognizing that its boldest claims will only survive if its methods do. The mixture of vesicle origins in infected hosts means that attributing a biological effect to the parasite, rather than to the host’s own response, requires careful experimental design, often involving purified parasite cultures and comparison with vesicles from uninfected host cells.

Taken together, the review makes a persuasive case for a conceptual shift. Extracellular vesicles in T. gondii are not metabolic exhaust, not incidental shedding from a busy cell, but strategic molecular messengers that operate at the interface between parasite and host, shaping infection from its earliest moments to its lifelong persistence. The work, published open access under a Creative Commons license with support from Brazil’s CAPES system, synthesizes mechanistic biology with translational ambition, and it arrives at a moment when vesicle biology is exploding across medicine, from cancer to neurodegeneration. For a parasite that infects such a vast share of humanity, understanding how it whispers to its host, through packets far too small to see, may prove as important as understanding how it invades. The conversation between Toxoplasma and its host, it turns out, has been conducted partly in a language scientists are only now learning to read.

Subject of Research: Extracellular vesicle-mediated host–parasite communication in Toxoplasma gondii infection

Article Title: Extracellular vesicles in Toxoplasma gondii: molecular messengers at the host–parasite interface

Article References: Balbino, E. F., Buso, L. S., de Oliveira, M. M., de Souza Martins, M. A. F., Bovolin, M. F., de Freitas Barbosa, B., Oliveira Gomes, A., Ramirez, M. I., Costa, I. N., & Rossi, I. V. (2026). Extracellular vesicles in Toxoplasma gondii: molecular messengers at the host–parasite interface. Parasites & Vectors. https://doi.org/10.1186/s13071-026-07622-8

Image Credits: AI Generated

DOI: 10.1186/s13071-026-07622-8

Keywords: Toxoplasma gondii, extracellular vesicles, exosomes, host–parasite interaction, immunomodulation, microRNAs, vesicle biogenesis, proteomics, biomarkers, vaccine platforms, drug delivery, toxoplasmosis

Mistletoes are among the most widespread canopy-dwelling parasitic plants in the world. Unlike fully parasitic species, hemiparasites such as T. bangwensis retain the ability to photosynthesise, but they rely on haustorial connections to tap into the vascular tissues of their hosts, drawing water, dissolved minerals and carbon compounds through these physiological lifelines. Because mistletoes transpire at exceptionally high rates, they maintain powerful water potential gradients that pull xylem sap preferentially through their own tissues rather than through the leaves of the host branch. Over time, this can turn the parasite into a mineral nutrient trap, accumulating elements at concentrations equal to or greater than those found in the foliage it feeds upon.

In cocoa, this interaction matters enormously. The crop depends on a carefully balanced supply of nitrogen, phosphorus, potassium, calcium, magnesium and a suite of micronutrients to sustain canopy growth, energy metabolism, stomatal regulation and the transport of assimilates that ultimately fill cocoa pods. Conventional nutrient management in cocoa systems rests on two pillars: soil fertility assessment and foliar nutrient diagnosis. Soil analyses indicate what is available for uptake, while leaf analyses provide an integrated snapshot of the tree’s actual nutritional status. The implicit assumption is that leaf chemistry largely mirrors soil supply. The new study shows that a parasite can break that assumption.

The scale of the mistletoe problem in West African cocoa is substantial. Surveys in Cameroon have reported infestation incidences exceeding 40 percent in some cocoa-growing communities, with the mistletoe Phragmanthera lapathifolia among the most common offenders. In Ghana, previous work has estimated that roughly 14 percent of all cocoa trees carry mistletoe, and more than 70 percent of those infestations involve T. bangwensis. Farmers readily recognise the visible symptoms, including branch weakening and dieback, but the nutritional consequences of infestation have remained poorly quantified, particularly in perennial tropical crops where nutrient cycling is complex and slow to respond to intervention.

To address this gap, a research team led by Michael Ansong of Kwame Nkrumah University of Science and Technology sampled fifteen smallholder cocoa farms across five communities in the Ahafo Ano North and Sefwi Wiawso districts of Ghana between May and July 2024. The farms, which averaged 0.90 hectares, sit within the humid cocoa belt on predominantly Ferralsols and Acrisols, receiving between roughly 1,300 and 1,750 millimetres of rain annually. On each farm, the researchers selected a pair of mature cocoa trees: one visibly infested with at least one active T. bangwensis plant attached to a main or secondary branch, and one confirmed uninfested after careful canopy inspection. The paired trees were matched for stem diameter, height, productive stage, canopy condition and shade environment, minimising confounding variation between the two members of each comparison.

Sampling was deliberately precise. From each infested tree, the team collected four mature, fully expanded cocoa leaves from the branch bearing the mistletoe, taken close to the attachment point and free of disease, herbivory or senescence. Four comparable leaves were taken from the same canopy positions on the uninfested partner tree, and four mature mistletoe leaves were harvested from the same infested branch. Each sample type was composited at the tree level. A single composite soil sample per farm, drawn from the 0 to 20 centimetre depth at five representative positions, characterised background farm fertility. All plant and soil samples were analysed at the university’s Soil Science Laboratory using standard methods: Kjeldahl digestion for nitrogen, molybdenum-blue colorimetry for phosphorus, EDTA titration for calcium and magnesium, turbidimetry for sulphur, flame photometry for potassium, and atomic absorption spectroscopy for iron, copper, zinc and manganese.

The results revealed a strikingly selective pattern of nutrient redistribution rather than a blanket depletion. Infested cocoa leaves contained significantly lower concentrations of nitrogen, phosphorus, potassium and copper than leaves from their uninfested partners. These are nutrients with high physiological stakes: nitrogen and phosphorus drive canopy development and energy metabolism, potassium governs stomatal regulation and assimilate transport, and copper, though needed only in trace amounts, is essential for enzyme activity, photosynthetic electron transport and oxidative stress defences. In contrast, infested leaves showed significantly higher concentrations of calcium and magnesium, while sulphur, iron, zinc and manganese showed no significant differences. The parasite, in other words, does not simply starve its host; it reorganises the host’s internal nutrient economy.

The elevated calcium and magnesium in infested leaves point to a plausible mechanism rooted in water relations. Because mistletoes transpire so vigorously, water arriving through the host branch is diverted through parasite tissues, reducing the flow that would otherwise deliver dissolved minerals to host leaves. Calcium and magnesium are relatively immobile once deposited in leaf tissues, so under this altered flow regime they can accumulate in older foliage rather than being redistributed to actively growing regions of the canopy. The mistletoe leaves themselves told a complementary story: they contained significantly higher concentrations of phosphorus, potassium, calcium, magnesium, sulphur and manganese than the host leaves on the same branch, confirming their role as nutrient-enriched sinks. Differences in nitrogen, iron, copper and zinc between parasite and host were not statistically significant.

Crucially, the team went beyond simple paired comparisons. Using nutrient-specific linear mixed-effects models, with infestation status and the corresponding soil nutrient as fixed effects and farm identity as a random intercept, they tested whether the infestation signal persisted once measured farm-level soil fertility was taken into account. It did. Soil phosphorus, calcium, magnesium, copper and zinc were significant predictors of the corresponding leaf nutrients, confirming that background fertility matters, but infestation remained significantly associated with lower leaf nitrogen, phosphorus, potassium and copper and higher leaf calcium and magnesium even after soil covariates were included. Soil sulphur, iron and manganese were not significant predictors of their leaf counterparts. Measured soil nutrients explained part, but not all, of the variation in cocoa leaf chemistry, leaving parasite-mediated redistribution as an independent and influential factor.

The practical implications are considerable. If low nutrient concentrations in infested cocoa leaves were caused purely by poor soil, fertiliser would correct them. But because the parasite acts as a sink that diverts nutrients after the host has already absorbed them, fertiliser alone is unlikely to restore balance while active mistletoe remains attached. The authors argue that foliar diagnosis in infested trees should always be interpreted alongside infestation status, and that soil fertility management will be most effective when combined with early detection, timely pruning and complete removal of active parasite tissues. For smallholder farmers, where fertiliser access is limited and mistletoe control demands labour-intensive manual pruning, that combined strategy may determine whether cocoa canopies, and the beans they produce, reach their full potential. The study also cautions that its farm-level soil sampling, one composite per farm, cannot capture tree-specific nutrient supply, and that future work with tree-level soil data, wider chemical characterisation and yield measurements would strengthen the soil-leaf-parasite picture. What is already clear, however, is that a parasite long treated as a visible nuisance is also an invisible accountant, quietly rewriting the nutrient ledgers of the trees it inhabits.

Subject of Research: Nutrient allocation between hemiparasitic mistletoe and its cocoa host trees

Article Title: Hemiparasitic mistletoe, Tapinanthus bangwensis, alters nutrient allocation in cocoa host-parasite systems

Article References: Ansong, M., Musah, S. A., Owusu, P., & Boadu, K. B. (2026). Hemiparasitic mistletoe, Tapinanthus bangwensis, alters nutrient allocation in cocoa host-parasite systems. Discover Plants, 3(1), Article 446. https://doi.org/10.1007/s44372-026-00936-y

Image Credits: AI Generated

DOI: 10.1007/s44372-026-00936-y

Keywords: mistletoe, Tapinanthus bangwensis, cocoa, hemiparasitic plants, nutrient allocation, foliar diagnosis, soil fertility, Ghana, host-parasite interaction, plant physiology, smallholder farms, mineral nutrition

Visceral leishmaniasis is not merely a localized skin infection; it attacks the spleen, liver and bone marrow, and it is fatal if untreated. Clinicians have long observed a curious metabolic signature in patients with active disease: elevated triglycerides and very low-density lipoprotein (VLDL), reduced high-density lipoprotein (HDL), and gene polymorphisms linked to lipid handling that appear to act as risk factors for developing overt illness. These observations suggested that lipids are not a side note in leishmaniasis but central players. What remained unknown was exactly which lipid classes change inside infected cells, when those changes occur, and whether they reflect parasite theft, host defense, or both. The new study set out to answer those questions at the level of individual molecular species.

The researchers infected human THP-1 macrophages, a standard model for the immune cells that harbor Leishmania in the body, and performed untargeted lipidomic profiling at two time points after infection. This approach allowed them to compare infected macrophages with uninfected controls and to analyze the intracellular amastigotes, the replicative form of the parasite that lives inside the host cell’s phagolysosomes. By measuring hundreds of lipid species across many structural classes, including phospholipids, sphingolipids, sterols, glycerolipids and fatty acids, the team could build a dynamic picture of how the lipid landscape of the host-parasite unit shifts over the course of infection.

The results were striking. Infection produced an enrichment of sterols, sphingolipids and phospholipids that correlated directly with the presence of L. infantum. The pattern of these changes points to substantial transfer of lipids from the host macrophage into the parasite, where exogenous fatty acids are remodeled into polyunsaturated species. In other words, the parasite does not simply scavenge intact host fats; it takes in raw fatty acid building blocks and reassembles them according to its own biochemical blueprint. This remodeling capacity is significant because polyunsaturated lipids influence membrane fluidity, signaling and stress responses, all of which matter for a parasite adapting to the harsh environment inside a macrophage.

At the same time, the host cell paid a heavy price. The infected macrophages showed depletion of mitochondrial lipids, including cardiolipin, the signature phospholipid of the inner mitochondrial membrane, as well as loss of glycosphingolipids. Cardiolipin is essential for oxidative phosphorylation and mitochondrial architecture, so its depletion suggests that the parasite’s lipid demands may compromise the energy machinery of the host cell. Glycosphingolipids, meanwhile, participate in membrane organization, cell signaling and immune recognition, and their loss could contribute to the immune evasion strategies for which Leishmania is well known. The study thus links the parasite’s appetite for fat to concrete, measurable damage in the host cell’s structural and functional lipid inventory.

One of the most intriguing findings is the biphasic nature of the lipid response. In the early phase, lipid metabolism appears geared toward the synthesis of amastigote biomass, supplying the membranes and storage molecules the parasite needs to grow and divide. Later, after the proliferative phase, the profile shifts toward accumulation of post-proliferative lipid storage, with lipids being stockpiled rather than immediately consumed. This two-stage program resembles a metabolic strategy seen in other intracellular pathogens: first exploit the host’s resources for expansion, then consolidate surplus into storage forms that can buffer the parasite against nutrient fluctuations. The timing of these phases, captured at two distinct time points, provides a temporal framework that earlier static snapshots of infection could not offer.

The technical depth of the lipidomic analysis is what makes these conclusions possible. Untargeted lipidomics does not presuppose which molecules matter; instead it surveys the lipidome broadly, detecting species ranging from lysophospholipids and diacylglycerols to cholesteryl esters, ceramides, plasmenyl phospholipids and coenzyme Q species. The authors were able to distinguish, for example, ceramides with short versus long N-acyl chains, and to track parasite-specific sterols such as ergosterol and its esters, which have no mammalian equivalent. That distinction matters: because Leishmania synthesizes ergostane-type sterols rather than cholesterol, the appearance and dynamics of these molecules serve as a molecular fingerprint of parasite lipid metabolism within the infected cell, cleanly separating parasite-driven changes from host responses.

The findings also connect the cellular picture to the clinical one. Patients with active visceral leishmaniasis show dyslipidemia, and the new data suggest a plausible mechanism: the parasite’s systematic extraction and remodeling of host lipids inside macrophages could ripple outward into systemic lipid disturbances. Furthermore, lipid-related gene polymorphisms identified as risk factors for overt disease may act by shaping how much lipid material is available to the parasite or how effectively host cells resist its manipulation. In this view, the outcome of infection depends partly on a metabolic tug-of-war, in which host lipid genetics and parasite lipid appetite together determine whether infection remains contained or blossoms into full disease.

Therapeutically, the study opens several doors. Lipid pathways that the parasite depends on but that differ from human biochemistry, such as ergosterol synthesis and the remodeling of scavenged fatty acids into polyunsaturated species, are attractive drug targets. Existing antifungal drugs exploit precisely this kind of sterol difference, and the new data map in detail which lipid classes accumulate or collapse during infection, offering a molecular checklist for interventions that could starve the parasite or protect host mitochondrial function. The biphasic pattern also carries a caution: any metabolic therapy would need to account for the stage of infection, since the parasite’s lipid requirements change as it shifts from proliferation to storage.

As a contribution to basic science, the work deepens the understanding of lipids’ central role in parasite growth and disease progression, an area that has lagged behind studies of genomes and proteins. It demonstrates that Leishmania infantum infection is not a passive coexistence but an active metabolic occupation, in which the parasite commandeers the host cell’s lipid economy with remarkable specificity and timing. For a disease that affects hundreds of thousands of people each year and remains one of the most neglected of the neglected tropical diseases, such mechanistic insight is a valuable step toward new strategies, whether drugs that block lipid transfer, biomarkers that track metabolic stages of infection, or a fuller explanation of why some patients’ lipid genetics leave them vulnerable. The parasite, it turns out, is truly hooked on fat, and understanding that addiction may be the key to breaking it.

Subject of Research: Host lipid manipulation by the protozoan parasite Leishmania infantum during macrophage infection

Article Title: Hooked on fat: host lipid manipulation by protozoan Leishmania infantum

Article References: Siess-Portugal, C., Chaves-Filho, A. B., Ozaki, C. Y., Ramos-Sanchez, E. M., Reis, L. C., Miyamoto, S., Yoshinaga, M. Y., & Goto, H. (2026). Hooked on fat: host lipid manipulation by protozoan Leishmania infantum. Parasites & Vectors. https://doi.org/10.1186/s13071-026-07691-9

Image Credits: AI Generated

DOI: 10.1186/s13071-026-07691-9

Keywords: Leishmania infantum, visceral leishmaniasis, lipidomics, host-parasite interaction, macrophages, lipid metabolism, sphingolipids, cholesterol trafficking, intracellular amastigotes, immune evasion, parasite physiology, neglected tropical diseases

The research team, led by Silvia Bainy Gastal of the Federal University of Rio Grande (FURG), together with Carolina Silveira Mascarenhas and Leandro Bugoni, examined the nasal cavities of 171 Kelp Gulls collected between 2015 and 2022 in the Brazilian states of Rio Grande do Sul, Santa Catarina, São Paulo and Rio de Janeiro. Most of the birds (146 individuals) had died under care at marine animal rehabilitation centers, while 25 were recovered during routine beach surveys. All carcasses were collected within 24 hours of the animal’s death, and none of the examined birds had received any antiparasitic treatment, ensuring that the mite counts reflected natural infection levels rather than the effects of medication.

Of the 171 gulls dissected, 56 — or 32.7 percent — were parasitized by rhinonyssid mites, and every specimen identified in the analyzed subsample proved to be Larinyssus orbicularis, a species first described in 1948 and known to specialize on gulls and terns. In total, the researchers recovered 2,224 mites, with a mean abundance of 13.0 mites per host across the whole sample and a mean intensity of 39.7 mites per parasitized bird. The species was confirmed using both light microscopy and scanning electron microscopy, the latter proving essential because the dorsal plates that serve as the mite’s diagnostic features were difficult to resolve with conventional optical equipment. Supplementary characters, including the shape and dimensions of the idiosoma, leg length, and the chaetotaxy of the dorsum, venter and gnathosoma, all matched the original description of L. orbicularis.

One of the study’s most striking results concerns infection intensity. Individual burdens ranged from a single mite to the record-setting 197, and because no standardized classification of Larinyssus infections in gulls existed before, the team proposed a semi-quantitative scheme based on the distribution of counts they observed: low infections of 1 to 20 mites, moderate infections of 21 to 50, and heavy infections exceeding 50 mites. Under this framework, 48.2 percent of parasitized gulls fell into the low category, 30.3 percent into the moderate category, and 21.5 percent carried heavy infections — meaning that roughly one in five infected birds hosted a substantial parasite load capable of occupying much of the nasal cavity.

Anatomically, the mites occupied the full length of the upper respiratory tract, from the rostral nasal conchae through the middle and caudal conchae. In heavily parasitized birds, the parasites were also found around the choana — the nasal opening of the palate — and very close to the nostrils, in some cases visible externally through the nares. Gross pathological examination revealed that most mites adhered to host tissue with only limited mucus, but in some individuals the researchers observed accumulated mucoid material, including tenacious mucus and bloody tenacious mucus surrounding the parasites. These observations echo earlier findings in Gouldian Finches infected with the related mite Sternostoma tracheacolum, suggesting that respiratory mite infections may produce similar mucosal changes across widely divergent bird groups.

Statistical analysis of the parasitological indices revealed a clear age-related pattern. Prevalence did not differ between male and female gulls, a result consistent with studies of Rhinonyssidae in other hosts such as the Rosy-billed Pochard and the Magellanic Penguin, and one that the authors interpret as evidence that transmission — whether during parental care or after fledging — is carried out equally by both sexes in these monogamous birds. Age, however, mattered significantly: only 11.8 percent of juveniles were infected, compared with 43.3 percent of immatures and 36.4 percent of adults. This mirrors the classic pattern reported by TerBush in 1963 for Herring Gulls in the United States, where juveniles showed similarly low infection rates, and supports the hypothesis that mite transmission to young gulls occurs predominantly after chicks have left the nest rather than inside the colony.

Geographically, the picture was equally telling. Of the 56 parasitized hosts, 55 were collected in Santa Catarina and just one in Rio Grande do Sul, while no mites were found in any of the gulls from São Paulo or Rio de Janeiro, despite those states contributing a smaller but meaningful number of carcasses. The authors caution that limited sampling in the northern states may partly explain the absence of positive records there, but they also point to host ecology as a plausible driver. In Brazil, Kelp Gulls breed on coastal islands along roughly 850 kilometers of shoreline, from Laguna in Santa Catarina northward to Rio de Janeiro, and the species relies on the coastal zone for foraging and resting. Because gulls gather in groups — including mixed flocks with tern species known to carry the same mite species — areas of high host density and overlapping species distributions may foster both intra- and interspecific mite transmission, shaping the observed latitudinal gradient in prevalence.

The transmission biology of rhinonyssid mites adds further ecological context. These obligate, blood-feeding endoparasites typically disperse through direct contact, moving between hosts when infected adults regurgitate food to nestlings or during courtship, although indirect transmission across water, perches and contaminated surfaces has also been documented. The researchers suggest that L. orbicularis, naturally associated with Kelp Gulls, may occasionally spill over into terns that share the same coastal environments, much as captive canaries have become secondarily infected with other rhinonyssids in regions where they were introduced. Such dynamics could help explain why the same mite species shows markedly different prevalence in different hosts — 9.1 percent in South American Terns and 50 percent in Cabot’s Terns in an earlier Brazilian study, versus 32.7 percent in Kelp Gulls here, and 24.8 percent and 4.5 percent in Herring Gulls previously examined in the United States and Russia respectively.

While rhinonyssids are generally considered to cause limited harm, the literature documents a range of potential pathologies: injury to the nasal epithelium and blood vessels, pulmonary congestion, rhinitis and sinusitis, and in captive birds even anorexia, aphonia, cachexia, air-sac inflammation, tracheitis and pneumonia that can prove fatal. The authors emphasize that future work should incorporate histopathological analysis of nasal tissues in parasitized gulls to determine whether L. orbicularis infections are associated with tissue lesions or respiratory disease, and they advocate for observations of clinical signs during rehabilitation combined with postmortem examinations as a practical pathway for studying live-host interactions. Because nasal mite infections cannot yet be readily diagnosed in living birds, carcasses from rehabilitation centers represent an invaluable but underused window into this hidden facet of avian health.

Ultimately, the study expands the known geographic distribution of L. orbicularis in Brazil, delivers the largest parasitological dataset ever compiled for nasal mites in gulls, and sets a methodological benchmark by demonstrating the value of scanning electron microscopy for species-level identification. The record intensity of 197 mites in a single bird, and the substantial proportion of heavily infected hosts, together make a compelling case that these minute inhabitants of the nasal cavity deserve far greater attention from ornithologists, parasitologists and wildlife rehabilitators alike. Whether Kelp Gulls have simply learned to tolerate their tenacious tenants, or whether the heaviest burdens carry hidden costs to survival and reproduction, remains an open question — but one that this new baseline now makes possible to answer.

Subject of Research: Prevalence, geographic distribution and parasitological indices of the nasal mite Larinyssus orbicularis in Kelp Gulls (Larus dominicanus) in Brazil

Article Title: Nasal Mites of Kelp Gulls (Larus dominicanus) in Brazil: Geographic Distribution and Parasitological Indices

Article References: Nasal Mites of Kelp Gulls (Larus dominicanus) in Brazil: Geographic Distribution and Parasitological Indices. (n.d.). https://doi.org/10.1007/s11686-026-01396-w

Image Credits: AI Generated

DOI: 10.1007/s11686-026-01396-w

Keywords: Kelp Gull, Larus dominicanus, nasal mites, Larinyssus orbicularis, Rhinonyssidae, parasitology, seabirds, Brazil, infection intensity, prevalence, scanning electron microscopy, host-parasite interaction