Occurrence of Stenurus globicephalae (Nematoda: Pseudaliidae) in the blowhole of Globicephala macrorhynchus (Cetacea: Delphinidae) in Tasmania, Australia.

Information about parasites of cetaceans in Australia is scarce and mostly opportunistic. The morphology of specimens of the metastrongyloid Stenurus globicephalae Baylis & Daubney, 1925 (Nematoda: Pseudaliidae), collected from the blowhole of a pilot whale Globicephala macrorhynchus Gray, 1846 (Cetacea: Delphinidae) off northern Tasmania, Australia, were studied. Light and scanning electron microscopical examinations enabled a detailed redescription of this nematode species, including corrections of some inaccuracies in previous species descriptions, particularly those concerning cephalic and caudal structures. The presence of numerous ventrolateral oblique muscle bands, characteristic of the males of S. globicephalae, is reported for the first time. This is the second finding of this nematode parasite, in a different host species, in Tasmania.

Nemabiome metabarcoding shows a high prevalence of Haemonchus contortus and predominance of Camelostrongylus mentulatus in alpaca herds in the northern UK.

Gastrointestinal nematodes (GINs) are a common threat faced by pastoral livestock. Since their major introduction to the UK in the early 1990s, South American camelids have been cograzed with sheep, horses, and other livestock, allowing exposure to a range of GIN species. However, there have been no molecular-based studies to investigate the GIN populations present in these camelids. In the current study, we sampled nine alpaca herds from northern England and southern Scotland and used high-throughput metabarcoded sequencing to describe their GIN species composition. A total of 71 amplicon sequence variants (ASVs) were identified representing eight known GIN species. Haemonchus contortus was the most prevalent species found in almost all herds in significant proportions. The identification of H. contortus in other livestock species is unusual in the northern UK, implying that alpacas may be suitable hosts and potential reservoirs for infection in other hosts. In addition, the camelid-adapted GIN species Camelostrongylus mentulatus was identified predominantly in herds with higher faecal egg counts. These findings highlight the value of applying advanced molecular methods, such as nemabiome metabarcoding to describe the dynamics of gastrointestinal nematode infections in novel situations. The results provide a strong base for further studies involving cograzing animals to confirm the potential role of alpacas in transmitting GIN species between hosts.

Efficacy of Bravecto® Plus spot-on solution for cats (280 mg/ml fluralaner and 14 mg/ml moxidectin) in the prevention of feline Aelurostrongylus abstrusus infection evaluated in a multi-diagnostic approach.

BACKGROUND: Aelurostrongylus abstrusus is one of the most important respiratory nematodes of felines. Infections may lead to respiratory clinical signs with varying severity or even death, emphasizing the need for preventive treatment of cats with outdoor access to circumvent patent infections. METHODS: Therefore, the preventive efficacy of a spot-on formulation of 280 mg/ml fluralaner and 14 mg/ml moxidectin (Bravecto® Plus spot-on solution for cats, MSD) against A. abstrusus was evaluated in a negative controlled, randomized and partially blinded efficacy study with 28 purpose-bred cats in a non-terminal design. In three different treatment regimes, the minimum recommended dose of 40 mg fluralaner and 2.0 mg moxidectin/kg bodyweight (BW) was administered once at 12, 8 or 4 weeks (study group G1, G2 and G3, respectively) prior to experimental infection with 300 third-stage A. abstrusus larvae, while G4 served as placebo-treated control. RESULTS: From 30 to 46 days post infection (dpi; SD 114 to 130), faeces were sampled to monitor first-stage larvae (L1) excretion for efficacy determination. Secondary efficacy criteria, including respiratory parameters, serological antibody levels and computed tomography (CT) findings, were assessed once before enrolment (SD -7 to -1) and before infection (SD 75 to 83). After infection, CT evaluation was performed once at 47-50 dpi (SD 131 to 134), and respiratory parameters and antibody levels were regularly assessed twice or once a week, respectively (1 up to 78 dpi, SD 85 up to 162). All animals in the control group excreted L1 by 33-37 dpi and remained positive throughout the study period from 41 to 46 dpi (SD 125 to 130). In the treatment groups, only one animal each of G1 and G2 excreted L1 at two consecutive days, and four cats of G1, two of G2 and three of G3 were positive on single occasions. While the geometric mean (GM) of the maximum number of excreted L1 per 5 g of faeces was 7380.89 in the control group (G4), GMs were significantly lower in the treatment groups with 1.63 in G1, 1.37 in G2 and 0.79 in G3. Thus, based on GMs, the reduction in excreted L1 exceeded 99.9% in all three treatment groups. Based on CT severity scores, all lungs of the animals of the control group showed severe pulmonary changes post infection, whereas lungs of the cats of the treatment groups were either unaltered (4 animals), mildly (11 animals), or moderately altered (5 animals). Moreover, seroconversion was observed in all cats of the control group, but not in those of the treatment groups. CONCLUSIONS: The combination of diagnostic methods used in this non-terminal study yielded coherent and reliable results. A single administration of Bravecto® Plus spot-on solution for cats was well tolerated and effective in the prevention of aelurostrongylosis for at least 12 weeks.

Control line failure in Angiostrongylus vasorum point-of-care serology test in dogs with angiostrongylosis due to suspected hook effect.

OBJECTIVES: Angiostrongylosis is a significant differential for a diverse range of clinical signs in dogs, many of whom present acutely and sometimes with fatal consequences. Point-of-care diagnostic assays include a commercially available Angiostrongylus vasorum qualitative direct lateral flow assay. MATERIALS AND METHODS: Case records from one referral centre from dogs with an invalid A. vasorum lateral flow assay, comprising an absent control line alongside a visible test line, were reviewed. As control line failure was hypothesised to be due to antigen excess; where available the A. vasorum lateral flow assay was repeated using dilutions of the original serum. RESULTS: Six dogs had an invalid A. vasorum lateral flow assay result. Five dogs had presented with acute-onset, severe clinical disease consistent with angiostrongylosis, and one dog was a clinically healthy in-contact. Clinical suspicion of angiostrongylosis was confirmed using alternative diagnostic testing and/or response to treatment. Repetition of the A. vasorum lateral flow assay, in four cases, using diluted plasma (10% to 12.5% v/v) resulted in the appearance of a control line alongside the visible test line. CLINICAL SIGNIFICANCE: A heavy burden of A. vasorum infection resulting in angiostrongylosis should be suspected in dogs with compatible clinical signs and an invalid A. vasorum lateral flow assay result due to control failure alongside a visible test line. Repetition of the test with a diluted serum may be considered to account for the hook effect, also known as the postzone phenomenon, as a possible cause.

Local terrestrial snails as natural intermediate hosts of the zoonotic parasite Angiostrongylus cantonensis in the new European endemic area of Valencia, Spain.

AIM: The rat lungworm, Angiostrongylus cantonensis, has recently been found in the city of Valencia, parasitizing rats, Rattus norvegicus and Rattus rattus, its natural definitive hosts. This is the first finding of this zoonotic nematode in continental Europe. After informing local and national health authorities, the collection of local terrestrial snails took place with the aim of elucidating their potential role as intermediate hosts of A. cantonensis. METHODS AND RESULTS: A total of 145 terrestrial snails, belonging to the species Cernuella virgata, Cornu aspersum, Eobania vermiculata, Otala punctata, Pseudotachea splendida, Rumina decollata and Theba pisana, were randomly collected between May and December 2022 in public gardens, parks and orchards in six districts of Valencia, in five of which A. cantonensis had been reported previously in rats. Once collected and identified, the snails were frozen at -20°C. Subsequently, the DNA was isolated and screened by PCR using specific primers targeting the A. cantonensis COI gene. Seven individual snails, belonging to the species C. virgata, C. aspersum and T. pisana, were positive, for an overall prevalence of 4.8%. The PCR product from one of them was sequenced by Sanger sequencing. CONCLUSIONS: The three positive terrestrial snail species are among the edible species that are frequently included in various dishes in Spain. C. virgata is reported as a previously unrecorded intermediate host and should be added to the list of more than 200 species of terrestrial snails that have been reported worldwide as intermediate hosts of the rat lungworm. Considering that these terrestrial snails may release infective larvae of A. cantonensis on leafy green vegetables on which they feed and during their handling and preparation for consumption, prophylactic measures to prevent human neuroangiostrongyliasis in Valencia and other regions to which this zoonotic parasite may spread are recommended.

Clinical bleeding diathesis, laboratory haemostatic aberrations and survival in dogs infected with Angiostrongylus vasorum: 180 cases (2005-2019).

OBJECTIVES: Bleeding diathesis is a complication in dogs infected with Angiostrongylus vasorum. This retrospective study investigated clinical and laboratory haemostatic differences in A. vasorum-positive dogs with and without signs of bleeding and impact of bleeding on survival. MATERIALS AND METHODS: Demographics, type of clinical bleeding, haematocrit and a range of haemostatic tests, including thromboelastography and derived velocity curves were retrospectively registered from A. vasorum-positive dogs. All parameters were compared between dogs with and without signs of bleeding using univariable analyses. Binomial and multinomial regression models were applied to examine specific indicators in the bleeding dogs. P-values were false discovery rate adjusted, and adjusted P<0.05 was considered significant. RESULTS: One hundred and eighty dogs entered the study, including 65 dogs (36.1%) presenting with bleeding diathesis. Different types of cutaneous and mucosal bleeding were the most common clinical findings. Twenty dogs presented with neurological signs associated with intracranial and intra-spinal bleeding. One hundred and thirty-seven dogs had haematological and/or haemostatic laboratory analyses performed. Haematocrit, platelet count, thromboelastographic angle, maximum amplitude, global clot strength, maximum rate of thrombin generation and total thrombin generation were decreased, while prothrombin time was prolonged in bleeding dogs. Survival rate of bleeding dogs was lower at hospital discharge (76.9%) and 1 month after diagnosis (66.0%) than in dogs without signs of bleeding (94.8% and 90.1% at discharge and at 1 month, respectively). CLINICAL SIGNIFICANCE: Several haemostatic aberrations were detected in A. vasorum-positive dogs with bleeding diathesis. Bleeding was identified as an important negative prognostic indicator in A. vasorum-positive dogs.

Refugia, climatic conditions and farm management factors as drivers of adaptation in Nematodirus battus populations.

Parasites are known for their ability to rapidly adapt to changing conditions. For parasitic helminths, changes in climate, along with farming and management practices associated with the intensification of livestock farming, provide novel challenges which can impact on their epidemiology and control. The sustainability of livestock production partially relies on effective control of helminth infection. Therefore, understanding changes in parasite behaviour, and what drives these, is of great importance. Nematodirus battus is an economically important helminth in the UK and temperate regions. Its infective larvae typically overwinter in eggs on pasture and hatch synchronously in spring, causing acute disease in lambs. Attempts to control disease typically rely on whole-flock benzimidazole (BZ) treatments. In recent years, the emergence of BZ-resistance, alongside the hatching of eggs without the classical over-winter 'chill stimulus', have made N. battus more difficult to control. In three previous studies, after collecting a large number of N. battus populations alongside farm management data from commercial farms, we explored the prevalence of genetic mutations associated with BZ-resistance (n = 253 farms), the ability of eggs to hatch with and without a chill stimulus (n = 90 farms) and how farm management practices varied throughout the UK (n = 187 farms). In the present study, we identify factors which may be acting as drivers, or barriers, to either the development of resistance or the variable hatching behaviour of N. battus eggs. Generalised linear mixed effect models were applied to regress experimental hatching and genotyping data on farm management and additional environmental data. Both variable hatching and resistance development appeared associated with the maintenance of parasite refugia as well as grazing management, particularly reseeding of pasture routinely grazed by young lambs each spring and the practice of set-stocked grazing. Effective quarantine measures were identified as the main protective factor for the development of BZ-resistance whereas set stocked grazing and population bottlenecks, resulting from reseeding heavily contaminated pastures, were risk factors. Spring maximum temperature and other climatic factors were associated with 'typical' hatching of eggs following a chill stimulus whilst several management factors were linked with hatching without prior chilling. For example, practices which reduce parasite numbers on pasture (e.g. re-seeding) or restrict availability of hosts (e.g. resting fields), were found to increase the odds of non-chill hatching. Retention of the timing of lambing and infection level of the host within the fitted model indicated that requirement for a chill stimulus prior to hatching may be plastic, perhaps subject to change throughout the grazing season, in response to immune development or parasite density-dependence within the host. Further investigation of the influence of the factors retained within the fitted models, particularly the theme of parasite refugia which was highlighted in relation to both the presence of BZ-resistance alleles and alternative hatching, is required to establish robust, sustainable parasite control and farm management strategies.

Factors associated with strongylida infections in sheep on farms in peri-urban Nairobi, Kenya.

Gastrointestinal parasite infections are among the major limitations to production in sheep in many parts of the world. It is important to continually assess their levels of infection in order to institute control measures and reduce the impact. This study determined the factors associated with the strongylida egg counts in sheep on selected farms in peri-urban Nairobi, Kenya. This was a cross-sectional study in which farm and animal-level data, including faecal samples, were collected from 1640 sheep from 30 purposively selected farms in Ruai, and Kamulu wards in Kasarani sub-county and Utawala and Mihango wards in Embakasi East Sub-County, in Nairobi County Kenya. The faecal samples were subjected to coprological examination using a modified McMaster technique to determine counts of strongylida eggs and coccidia oocysts with a detection level of 100 egg or oocyst per gram (EPG or OPG) of faeces. The positive faecal samples for strongylida eggs were pooled per farm and cultured for morphological identification of larval stage three. Descriptive statistics and multilevel mixed-effect logistic regression analyses were used to determine factors associated with strongylida egg count ≥600 EPG (p < 0.05). The receiver operating characteristics curve was used to assess the overall diagnostic performance in the final model. Strongylida eggs were detected in 45.5% (746/1640) of the sheep, and the mean EPG was 486.0± 858.9 with a median of 200 and a range of 0-16,700. The coccidia oocysts were detected in 49.4% (810/1640) of the sheep with a mean OPG was 341.7± 1782.4, a median of 0 and a range of 0-60,000. In the coprocultures, the nematode genera identified (% differential count of L3) were Haemonchus (90%), Trichostrongylus (5%) and Oesophagostomum (5%). In the final multivariable regression model, the odds of detecting EPG ≥ 600 was 1.44 times higher for sheep shedding coccidia oocysts than those that did not. The odds for detecting EPG ≥ 600 was 4.01 times for sheep in Ruai ward compared with those in the combined Kamulu, Utawala and Mihango wards. The receiver operating characteristic curve area was 73.1%, suggestive of good model performance. The results suggest that gastrointestinal strongylida and coccidia infections are common in sheep and farmers should be educated on the importance of appropriate control measures.

Semperula wallacei (Mollusca, Veronicellidae) um hospedeiro natural recém-descoberto de Angiostrongylus cantonensis (Nematoda, Angiostrongylidae) na Bacia do Pacífico.

Semperula wallacei (Issel, 1874) is a species of terrestrial slug that occurs in southeast China and the Pacific Basin and is the only species of its genus that occurs beyond the Oriental region and to the east of Wallace's line in the Australian region, where it has probably been introduced. In this study, we report for the first time S. wallacei as an intermediate host for Angiostrongylus cantonensis (Chen, 1935) based on histological and molecular analyses of slugs from Tuamasaga, Samoa, deposited at the Medical Malacological Collection (Fiocruz-CMM). DNA was obtained from the deparafinized tissues scraped from specimen slides. Polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) targeted to the internal transcribed spacer 2 (ITS2) region were carried out using the restriction enzyme Cla I. The RFLP profile observed for our larval specimen of S. wallacei was identical to the profile previously established for A. cantonensis, demonstrating that S. wallacei can be naturally infected with A. cantonensis and is likely to be an intermediate host for this parasitic nematode species in the field. The potential for geographical range expansion of S. wallacei in the Pacific Basin, its small size, and the general role of veronicellids as crop pests and hosts of nematodes, indicate the significance of S. wallacei as an invasive species in the Pacific Basin. Our work also highlights the importance of biological collections for investigating the environmental impact of invasive species on agriculture, public health, and biodiversity conservation.

Angiostrongylus dujardini infection in a coconut lorikeet (Trichoglossus haematodus) from a zoological garden in Switzerland.

Angiostrongylus spp. (Metastrongyloidea) can cause severe disease in several animal species and humans. This report describes an infection with Angiostrongylus dujardini in a captive coconut lorikeet (Trichoglossus haematodus) from a zoo in Switzerland. The bird was reported being attacked by conspecifics, removed from the flock, and hospitalized. It showed lethargy, moderately reduced body condition, and lack of reaction to visual stimuli. Analgesic and antibiotic treatment were initiated but because of worsening of its general condition, the bird was euthanized the following day. Necropsy revealed multifocal, subcutaneous hemorrhages, diffusely reddened lungs and a moderately dilated right heart with several intraluminal nematodes embedded in a coagulum. Four worms were collected and microscopically examined. They were identified as adult females, measuring 19-21 mm long x 0.4-0.5 mm wide, with general morphological and morphometric characteristics consistent with angiostrongylid nematodes. In lung sections, multifocal collection of thin-walled embryonated eggs in variable stages of development was observed along with fully developed nematode larvae within the lumina of alveoli and lung vessels. Associated granulomatous infiltrates indicated a severe, multifocal, chronic, granulomatous pneumonia. The diagnosis of A. dujardini infection was formulated by morphological examination of adult and larval stages, supported by molecular analysis (PCR-amplification and sequencing of the ITS2, 5.8S and 28S rDNA flanking regions). This is the first report of A. dujardini infection in an avian species, providing evidence that birds can serve as accidental hosts of this parasite in addition to mammals, and that the parasite can reach maturity and multiply in the avian cardiorespiratory system.

A Taq-Man-based multiplex quantitative PCR for the simultaneous detection and quantification of Angiostrongylus vasorum, Crenosoma vulpis, and species of respiratory capillarids in canids.

In recent years, Angiostrongylus vasorum, Crenosoma vulpis, Eucoleus aerophilus (syn. Capillaria aerophila) and Eucoleus boehmi (syn. Capillaria boehmi), commonly referred to as canine lungworms, have gained a growing interest worldwide as the result of their geographical expansion. Each of these nematode species differs considerably in its biology and pathogenicity. Despite their impact on dogs' health, these parasites are often underdiagnosed owing to diagnostic challenges. Here, we describe the development and validation of a Taq-Man-based multiplex quantitative PCR (qPCR) for the simultaneous detection of the main species of canine lungworms in faeces of infected dogs. Using 10-fold serial dilutions of synthetic gene block fragments containing individual sequence targets of each lungworm species, the analytical sensitivity of the assay ascertained was 1.84 ng/µl for A. vasorum, 3.08 ng/µl for C. vulpis and 0.79 ng/µl for Eucoleus spp. The sensitivity of the assays and their ability to detect mixed species infections were compared with microscopy-based techniques (faecal floatation and Baermann technique) applied to faecal samples submitted for lungworm testing through an accredited diagnostic laboratory at the Institute of Parasitology, University of Zurich, Switzerland, and from community dogs as part of a research project on canine endoparasites in Cambodia. The multiplex qPCR displayed high diagnostic sensitivity (42/46, 91.3%; 95% Confidence Interval (CI): 79.1-97.1%) and a diagnostic specificity of 100% (45/45, 95% CI: 90.6-100%), and was able to detect 42.9% additional mixed lungworm species infections compared with microscopy-based methods. Kappa statistics showed substantial agreement between the qPCRs and microscopy for mixed infections (κ = 0.72, 95% CI: 0.4-1) and Eucoleus spp. (κ = 0.65, 95% CI: 0.45-0.85) and almost perfect agreement for C. vulpis (κ = 0.85, 95% CI: 0.63-1) and A. vasorum (κ = 0.92, 95% CI: 0.84-1). This multiplex qPCR enables timely, accurate, and sensitive diagnosis of canine lungworm species in faecal samples and can be used to monitor the geographical distribution and emergence of these parasitic species, globally.

Comparative analysis of diagnostic methods and risk factors for Aelurostrongylus abstrusus infection in brazilian cats.

This study aimed to prospectively evaluate the risk factors of infection by Aelurostrongylus abstrusus in Brazilian cats with cough and/or radiographic changes, using as diagnostic tools the Baermann method (BM), polymerase chain reaction (PCR) of feces, bronchoalveolar lavage fluid (BALF), and cytology. Forty-three cats that were presented with cough or lung radiographic abnormalities compatible with bronchoalveolar disease were included in the study. After clinical evaluation, feces samples were collected to investigate lungworm parasitism through BM and PCR. BALF was performed to provide samples for cytology, bacteriology, and fungal culture. Stool PCR was considered the gold standard for diagnosis tests, and the other methods were evaluated by their agreement. PCR presented 74% (32/43) of positivity for A. abstrusus, while in the BM, 41% (18/43) were positive. BM showed sensitivity of 56.25% and specificity of 100% when compared with PCR. No larva was found in the cytological evaluation of 21 BALF samples. Lungworm is an important cause of bronchopulmonary disease in domestic cats in Brazil and should be included as a differential diagnosis when a cat is presented with cough or radiographic abnormalities. BM is a sensitive, non-invasive, and cheap technique to diagnose the disease, but it is not as sensitive as PCR.

Angiostrongylus cantonensis Infection in Brown Rats (Rattus norvegicus), Atlanta, Georgia, USA, 2019-2022.

Rat lungworm (Angiostrongylus cantonensis), a zoonotic parasite invasive to the United States, causes eosinophilic meningoencephalitis. A. cantonensis harbors in rat reservoir hosts and is transmitted through gastropods and other paratenic hosts. We discuss the public health relevance of autochthonous A. cantonensis cases in brown rats (Rattus norvegicus) in Atlanta, Georgia, USA.

Molecular prevalence, phylogenetic characterization, and epidemiological risk factors of pulmonary nematodes in domestic cats in Türkiye.

Aelurostrongylus abstrusus, Oslerus rostratus, and Troglostrongylus brevior are nematodes found in the respiratory system of domestic cats and cause a variety of symptoms. All three parasites use the same hosts and niches, and the morphological measurements of their L1s excreted in faeces overlap with each other. In this study, 300 cats brought to Ondokuz Mayis University Veterinary Teaching Animal Hospital were screened for lungworms by morphological measurements and molecular analyses. The prevalence of the lungworms was found as 1.33% (4/300) for A. abstrusus, 0.66% (2/300) for O. rostratus, and 0.33% (1/300) for T. brevior. Molecular identification of A. abstrusus, T. brevior, and O. rostratus in domestic cats was carried out for the first time in Türkiye within the present study. This study also reveals the risk factors of lungworm positivity in domestic cats in Türkiye.

The recent introduction of Angiostrongylus cantonensis and its intermediate host Achatina fulica into Guadeloupe detected by phylogenetic analyses.

BACKGROUND: Angiostrongylus cantonensis (rat lungworm) is the main pathogen responsible for eosinophilic meningitis in humans. One of its intermediate snail hosts, Achatina fulica, was already present in many countries around the world before it appeared in the West Indies in the late 1980s. In the French territories in the Caribbean and northern South America, the first cases of human neuroangiostrongyliasis were reported in Martinique, Guadeloupe and French Guiana in 2002, 2013 and 2017, respectively. In order to better characterize angiostrongyliasis in Guadeloupe, particularly its geographical origin and route of introduction, we undertook molecular characterization of adult worms of Angiostrongylus cantonensis and its intermediate host Achatina fulica. METHODS: Genomic DNA of adult Angiostrongylus cantonensis and Achatina fulica was extracted and amplified by polymerase chain reaction (PCR) targeting the mitochondrial genes cytochrome B and C for A. cantonensis and 16S ribosomal RNA for A. fulica. The PCR products were sequenced and studied by phylogenetic analysis. RESULTS: Cytochrome B and cytochrome C molecular markers indicate a monophyletic lineage of A. cantonensis adult worms in Guadeloupe. Two sequences of A. fulica were identified. CONCLUSIONS: These results confirm the recent introduction of both Angiostrongylus cantonensis and Achatina fulica into Guadeloupe. Achatina fulica in Guadeloupe shares a common origin with those in Barbados and New Caledonia, while Angiostrongylus cantonensis in Guadeloupe shares a common origin with those in Brazil, Hawaii and Japan.

Rat lungworm survives winter: experimental overwintering of Angiostrongylus cantonensis larvae in European slugs.

The rat lungworm Angiostrongylus cantonensis is a metastrongyloid nematode that causes neurological disorders in its accidental hosts, including humans. This invasive pathogen is native to Southeast Asia and adjacent regions and is gradually expanding its distribution to tropical and subtropical areas with new foci discovered near temperate regions. The parasite has a complex life cycle with a range of gastropods serving as intermediate hosts. A broad spectrum of poikilotherm vertebrates and invertebrates can serve as paratenic hosts. Since it has already been demonstrated that other, non-zoonotic metastrongyloids can survive in their intermediate hosts during the winter, the aim of our study was to evaluate the survival of A. cantonensis third-stage larvae in experimentally infected slugs (Limax maximus) kept at 4.5­7°C for 60 days. Third-stage larvae of A. cantonensis survived the period of low temperature and remained capable of infecting definitive hosts (laboratory rats) afterwards, even though their numbers dropped significantly. These results suggest that further spread to higher latitudes or altitudes is possible in areas with sufficient abundance of definitive hosts, since low winter temperatures are not necessarily an obstacle to the spread of the parasite.

A cross-sectional study of Angiostrongylus malaysiensis in rats and gastropod hosts from recreational parks in Kuala Lumpur, Malaysia: Detection, risk factors and pathology.

Angiostrongylus malaysiensis is a potential zoonotic parasite, which reported to co-occur with A. cantonensis in human cerebrospinal fluid. It is a heteroxenous nematode that primarily develops through the early larval stages in gastropods and attains sexual maturity within rats. This study was conducted to determine the host species responsible for the reservoir of A. malaysiensis and investigate the risk factor for transmission among the hosts in Kuala Lumpur, Malaysia. Sampling was conducted in six recreational parks. The rats were trapped alive using steel wire traps with bait, while the gastropods were collected by active searching. The rats were euthanized and dissected to collect any adult worms observed. The molecular detection of A. malaysiensis was performed by PCR on gastropod tissue samples. Biotic and landscape factors were recorded for risk factor analysis. In total, 82 rats and 330 gastropods were collected throughout the study. Overall, 3.64% of gastropods and 32.9% of rats were infected with A. malaysiensis. Rattus tiomanicus (Malayan wood rat) and Parmarion martensi (Yellow-shelled semi-slug) were found as important hosts for A. malaysiensis. Host species, sampling site and macrohabitat type are risk factors associated with the prevalence of A. malaysiensis infection in rats. For gastropods, host species and sampling site are risk factors that correlate with the parasite detection. In total, 128 adult A. malaysiensis were recovered from the infected rats. The mean intensity of infection with adult A. malaysiensis was 4.65 for Rattus rattus complex and 4.90 for R. tiomanicus. Adult worms were found in the pulmonary artery or right ventricle, while eggs and first-stage larvae were found in capillaries of the caudal lung lobe. Infected lungs showed extravasated red blood cells in the alveolar spaces. The pulmonary arteries in the infected lung lobe were thickened. Kepong Metropolitan Park is the hotspot area for A. malaysiensis in Kuala Lumpur. These results provide essential information for public health officials to develop targeted interventions to reduce the transmission of A. malaysiensis in urban areas, particularly in recreational parks.

Comparative biology of parasitic nematodes in the genus Angiostrongylus and related genera.

The rise to prominence of some Angiostrongylus species through associated emerging disease in humans and dogs has stimulated calls for a renewed focus on the biology of this genus and three related genera. Although significant research efforts have been made in recent years these have tended to focus on individual species and specific aspects such as diagnosis and treatment of disease or new records of occurrence and hosts. This comprehensive review takes a comparative approach, seeking commonalities and differences among species and asking such questions as: Which species belong to this and to closely related genera and how are they related? Why do only some species appear to be spreading geographically and what factors might underlie range expansion? Which animal species are involved in the life cycles as definitive, intermediate, paratenic and accidental hosts? How do parasite larvae find, infect and develop within these hosts? What are the consequences of infection for host health? How will climate change affect future spread and global health? Appreciating how species resemble and differ from each other shines a spotlight on knowledge gaps and provides provisional guidance on key species characteristics warranting detailed study. Similarities exist among species, including the basic life cycle and transmission processes, but important details such as host range, climatic requirements, migration patterns within hosts and disease mechanisms differ, with much more information available for A. cantonensis and A. vasorum than for other species. Nonetheless, comparison across Angiostrongylus reveals some common patterns. Historically narrow definitive host ranges are expanding with new knowledge, combining with very broad ranges of intermediate gastropod hosts and vertebrate and invertebrate paratenic and accidental hosts to provide the backdrop to complex interactions among climate, ecology and transmission that remain only partly understood, even for the species of dominant concern. Key outstanding questions concern larval dynamics and the potential for transmission outside trophic relations, relations between infection and disease severity in different hosts, and how global change is altering transmission beyond immediate impacts on development rate in gastropods. The concept of encounter and compatibility filters could help to explain differences in the relative importance of different gastropod species as intermediate hosts and determine the importance of host community composition and related environmental factors to transmission and range. Across the group, it remains unclear what, physiologically, immunologically or taxonomically, delimits definitive, accidental and paratenic hosts. Impacts of infection on definitive host fitness and consequences for population dynamics and transmission remain mostly unexplored across the genus. Continual updating and cross-referencing across species of Angiostrongylus and related genera is important to synthesise rapid advances in understanding of key traits and behaviours, especially in important Angiostrongylus species that are emerging causative agents of disease in humans and other animals.

[Prevalence of Angiostrongylus cantonensis infection in snails in Fujian Province from 2017 to 2021].

OBJECTIVE: To investigate the prevalence of Angiostrongylus cantonensis infection in market-sold and field-captured snails in Fujian Province, so as to provide the scientific basis for the formulation of the angiostrongyliasis control measures. METHODS: In each month from May to October during the period from 2017 through 2021, Pomacea snails were collected from two field fixed surveillance sites and Bellamya aeruginosa collected from one agricultural product market in Fuzhou City, while Pomacea and B. aeruginosa snails were collected from two agricultural product markets and four restaurants in Xiamen City. At least 50 Pomacea snails and 500 g B. aeruginosa were sampled each time. A. cantonensis infection was detected in Pomacea snails using lung microscopy, and in B. aeruginosa using a tissue homogenate method. RESULTS: A total of 9 531 Pomacea snails were detected for A. cantonensis infection in two cities of Fuzhou and Xiamen, and the overall prevalence of A. cantonensis infection was 4.40%, with the highest prevalence in 2017 (6.82%, 116/1 701) and the lowest prevalence in 2019 (3.46%, 83/2 400). The prevalence of A. cantonensis infection was significantly higher in Pomacea snails sampled from Fuzhou City (11.23%, 326/2 903) than from Xiamen City (1.40%, 93/6 628) (χ2 = 461.48, P < 0.01). A. cantonensis larvae were detected in larval Pomacea snails in two cities of Fuzhou and Xiamen each month. The prevalence of A. cantonensis infection in Pomacea snails appeared an overall tendency towards a rise with month in Fuzhou City, with the highest prevalence in October (15.24%), and there was a significant difference among month (χ2 = 14.56, P < 0.05), while the prevalence of A. cantonensis infection in Pomacea snails was low in Pomacea snails sampled from Xiamen City each month, with the highest prevalence in June (2.64%), and there was a significant difference among month (χ2 = 23.17, P < 0.05). A total of 18 966 B. aeruginosa snails were detected for A. cantonensis infection in two cities of Fuzhou and Xiamen, and the overall prevalence of A. cantonensis infection was 0.01%. CONCLUSIONS: A. cantonensis infection was identified in Pomacea and B. aeruginosa snails in Fujian Province from 2017 to 2021, and there is a potential risk of human A. cantonensis infection.

Diagnostic challenges for Aelurostrongylus abstrusus infection in cats from endemic areas in Italy.

BACKGROUND: The lungworm Aelurostrongylus abstrusus infects wild and domestic feline species worldwide and is considered a primary respiratory parasite of cats. Definitive diagnosis is based on the identification of first-stage larvae (L1s) released in faeces approximately 5 to 6 weeks after infection. More recently, serology has been shown to be a diagnostic alternative for A. abstrusus infection in cats. The present study aimed at evaluating the diagnostic performance of serological antibody detection compared to faecal examination for A. abstrusus infection in a population of cats with known infection status from endemic areas in Italy and to identify factors (larval scores, age, co-infections with other helminths) that may influence test sensitivity and specificity of serology. METHODS: All cats resulting positive using the Baermann technique (n = 78) were tested with the A. abstrusus ELISA. An additional 90 serum samples from cats living in three geographical areas with infection prevalence > 10%, but that resulted negative on Baermann, were also tested. RESULTS: Among 78 cats copromicroscopically positive for L1s of A. abstrusus (Group 1), 29 (37.2%) were seropositive in ELISA. Of the 90 cats from Group 2 (cats living in three geographical areas in Italy with A. abstrusus prevalence > than 10%, but negative on Baermann examination), 11 (12.2%) were positive on ELISA. The overall seroprevalence was 23.8%. There was no statistical difference either between average optical density (OD) values of cats excreting > 100 L1s vs. cats excreting < 100 L1s (0.84 vs. 0.66; P value = 0.3247) or comparing the OD values with age of infected cats. Few Baermann-negative cats positive for Toxocara cati or hookworms were seropositive, supporting lack of cross-reactivity to these nematodes. CONCLUSIONS: Results from the present study suggest that relying solely on faecal examination may underestimate prevalence of A. abstrusus infection in cats and that field surveys based on antibody detection are useful for establishing true prevalence of infected and/or exposed animals.