Update on eosinophilic meningoencephalitis and its clinical relevance

Detection of rat lungworm (Angiostrongylus cantonensis) infection by real-time PCR from the peripheral blood of animals: a preliminary study

Rat lungworm disease or neuroangiostrongyliasis is a cerebral parasitic infection that affects humans and animals alike. Its clinical signs and symptoms can range from mild self-resolving to serious life-threatening conditions. Studies suggest therapeutic interventions during the early stages of infection to be more effective than in later stages. However, early diagnosis of infection is usually problematic without the knowledge of exposure and/or detection of the parasite's DNA or antibody against the parasite in the cerebrospinal fluid. This requires a lumbar puncture, which is an invasive procedure that generally requires hospitalization. This study evaluates an affordable and less invasive alternative to detect parasitic DNA by PCR from the peripheral blood of potentially infected animals. Blood samples from 58 animals (55 dogs and 3 cats) with clinical suspicion of infection were submitted to our lab between February 2019 and August 2022 by local, licensed veterinarians. DNA was extracted from whole blood, plasma, serum, and/or packed cells using the Qiagen DNeasy Blood & Tissue Kit as per the manufacturer's protocol. All 58 animals were tested by real-time PCR using the AcanITS1 assay and 32 of these animals (31dogs; 1 cat) were also tested using the AcanR3990 assay. The PCR results for both assays were classified into strongly positive > positive > weakly positive > negative, and equivocal for ambiguous results, based on the strength of the signal. The percent infection detected using the AcanITS1 and AcanR3990 assays was 12.72% (7/55) and 20.68% (6/29), respectively. The overall percent infection detected was 34.37% (11/32), with only two animals testing positive by both assays. The three cats involved in this study tested negative by both assays. These results are promising and warrant further investigations to increase sensitivity including variables that might affect detection in the blood, such as parasite load, and laboratory methodologies.

Insights into the epidemiology, pathogenesis, and differential diagnosis of schistosomiasis

Schistosomiasis is a neglected tropical disease that is prevalent in low- and middle-income countries. There are five human pathogenic species, of which Schistosoma haematobium, Schistosoma mansoni and Schistosoma japonicum are the most prevalent worldwide and cause the greatest burden of disease in terms of mortality and morbidity. In addition, hybrid schistosomes have been identified through molecular analysis. Human infection occurs when cercariae, the larval form of the parasite, penetrate the skin of people while bathing in contaminated waters such as lakes and rivers. Schistosomiasis can cause both urogenital and intestinal symptoms. Urogenital symptoms include haematuria, bladder fibrosis, kidney damage, and an increased risk of bladder cancer. Intestinal symptoms may include abdominal pain, sometimes accompanied by diarrhoea and blood in the stool. Schistosomiasis affects more than 250 million people and causes approximately 70 million Disability-Adjusted Life Years (DALYs), mainly in Africa, South America, and Asia. To control infection, it is essential to establish sensitive and specific diagnostic tests for epidemiological surveillance and morbidity reduction. This review provides an overview of schistosomiasis, with a focus on available diagnostic tools for Schistosoma spp. Current molecular detection methods and progress in the development of new diagnostics for schistosomiasis infection are also discussed.

Inflammatory and immunopathological differences in brains of permissive and non-permissive hosts with Angiostrongylus cantonensis infection can be identified using 18F/FDG/PET-imaging

BACKGROUND

Angiostrongylus cantonensis is a parasite that mainly infects the heart and pulmonary arteries of rats and causes human eosinophilic meningitis or meningoencephalitis in certain geographical areas. Current diagnostic methods include detection of the parasite in cerebrospinal fluid (CSF) and eosinophilic immune examination after lumbar puncture, which may be risky and produce false-positive results. 18F- Fluorodeoxyglucose (FDG), a Positron emission tomography (PET) tracer, has been used to assess different pathological or inflammatory changes in the brains of patients. In this study, we hypothesized that A. cantonensis infection-induced inflammatory and immunomodulatory factors of eosinophils result in localized pathological changes in the brains of non-permissive hosts, which could be analyzed using in vivo 18F-FDG PET imaging.

METHODOLOGY/FINDINGS

Non-permissive host ICR mice and permissive host SD rats were infected with A. cantonensis, and the effects of the resulting inflammation on 18F-FDG uptake were characterized using PET imaging. We also quantitatively measured the distributed uptake values of different brain regions to build an evaluated imaging model of localized neuropathological damage caused by eosinophilic inflammation. Our results showed that the uptake of 18F-FDG increased in the cerebellum, brainstem, and limbic system of mice at three weeks post-infection, whereas the uptake in the rat brain was not significant. Immunohistochemical staining and western blotting revealed that Iba-1, a microglia-specific marker, significantly increased in the hippocampus and its surrounding area in mice after three weeks of infection, and then became pronounced after four weeks of infection; while YM-1, an eosinophilic chemotactic factor, in the hippocampus and midbrain, increased significantly from two weeks post-infection, sharply escalated after three weeks of infection, and peaked after four weeks of infection. Cytometric bead array (CBA) analysis revealed that the expression of TNF in the serum of mice increased concomitantly with the prolongation of infection duration. Furthermore, IFN-γ and IL-4 in rat serum were significantly higher than in mouse serum at two weeks post-infection, indicating significantly different immune responses in the brains of rats and mice. We suggest that 18F-FDG uptake in the host brain may be attributed to the accumulation of large numbers of immune cells, especially the metabolic burst of activated eosinophils, which are attracted to and induced by activated microglia in the brain.

CONCLUSIONS

An in vivo 18F-FDG/PET imaging model can be used to evaluate live neuroinflammatory pathological changes in the brains of A. cantonensis-infected mice and rats.

Doxycycline cotherapy with albendazole relieves neural function damage in C57BL/6 and BALB/c mice infected with Angiostrongylus cantonensis

BACKGROUND

We investigated the effects of combination therapy albendazole and doxycycline in Angiostrongylus cantonensis-infected mice during early and late treatment.

MATERIALS AND METHODS

C57BL/6 and BALB/c mice were divided into five groups: (i) uninfected, (ii) infected with A. cantonensis, (iii) infected + 10 mg/kg albendazole, (iv) infected + 25mg/kg doxycycline, and (v) infected + 10 mg/kg albendazole + 25 mg/kg doxycycline. We administered drugs in both early treatments started at 7-day post infections (dpi) and late treatments (14 dpi) to A. cantonensis-infected C57BL/6 and BALB/c mice. To assess the impact of these treatments, we employed the Morris water maze test to evaluate spatial learning and memory abilities, and the rotarod test to measure motor coordination and balance in C57BL/6 mice. Additionally, we monitored the expression of the cytokine IL-33 and GFAP in the brain of these mice using western blot analysis.

RESULTS

In this study, A. cantonensis infection was observed to cause extensive cerebral angiostrongyliasis in C57BL/6 mice. This condition significantly affected their spatial learning and memory abilities, as assessed by the Morris water maze test, as well as their motor coordination, which was evaluated using the rotarod test. Early treatment with albendazole led to favorable recovery outcomes. Both C57BL/6 and BALB/c mice express IL-33 and GFAP after co-therapy. The differences of levels and patterns of IL-33 and GFAP expression in mice may be influenced by the balance between pro-inflammatory and anti-inflammatory signals within the immune system.

CONCLUSIONS

Combination therapy with anthelmintics and antibiotics in the early stage of A. cantonensis infection, in C57BL/6 and BALB/c mice resulted in the death of parasites in the brain and reduced the subsequent neural function damage and slowed brain damage and neurobehavior impairment. This study suggests a more effective and novel treatment, and drug delivery method for brain lesions that can decrease the neurological damage of angiostrongyliasis patients.

Eosinophilic meningoencephalitis successfully treated with glucocorticoids and intravenous immunoglobulin: a case report

Eosinophilic meningoencephalitis is a rare inflammatory condition of the central nervous system. As a limited number of cases has been reported, debate remains on the optimal treatment. We present a case of idiopathic eosinophilic meningoencephalitis successfully treated with glucocorticoids and intravenous immunoglobulin (IVIG). After extensive evaluation to rule out other possible causes, the patient was treated with intravenous (IV) dexamethasone and showed significant improvement within a few days. However, neurologic impairment persisted, and follow-up lumbar puncture results showed only a mild decrease in pleocytosis. Even after an additional 5 days of IV methylprednisolone, cerebrospinal fluid (CSF) pleocytosis persisted, and brain magnetic resonance imaging (MRI) showed an increase in enhanced lesions, implying persistent neuroinflammation. The patient was maintained on high-dose oral prednisolone for 2 months, and additional immune-modulatory effects were treated with IVIG. Follow-up MRI at 2 months showed a significant decrease in the extent of multiple enhanced lesions and a normalized CSF profile. The patient was maintained on regular maintenance doses of IVIG for an additional 6 months without any neurologic signs or symptoms. Inflammation is the key pathophysiology underlying neurological damage in eosinophilic meningoencephalitis. A literature review revealed that corticosteroid treatment is the only anti-inflammatory treatment used in cases of idiopathic meningoencephalitis, resulting in sufficient response in most patients but only partial response or death in a few cases. This is the first case report of IVIG use in idiopathic eosinophilic meningoencephalitis, suggesting the possibility of a new treatment modality for refractory cases.

Gnathostoma infection after ingestion of raw fish is a probable cause of eosinophilic meningitis in the Brazilian Amazon

We report a case of eosinophilic meningitis associated with the ingestion of raw fish (Cichla sp.) from the Brazilian Amazon, likely caused by Gnathostoma. A 36-year-old male visited Juruena river on a fishing trip. After 50 days, the patient presented with an intense frontal headache. A cerebrospinal fluid examination revealed 63% eosinophilia. Another individual who ingested raw fish developed linear dermatitis on the abdominal wall. Anti-Gnathostoma serum antibodies were detected, and the patient made a full recovery after treatment with corticosteroids and albendazole. To date, autochthonous Gnathostoma spp. infections in Latin American countries have only caused linear panniculitis. This report raises awareness of gnathostomiasis-causing meningitis.

case of autoimmune GFAP astrocytopathy with eosinophils in the cerebrospinal fluid

Cerebrospinal fluid (CSF) eosinophilia is associated with a narrow differential, primarily including parasitic and fungal infections, neoplasm, and chemical meningitis. It has rarely been reported in neuroinflammatory conditions including as a finding of CSF cytology in two autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy cases. Here we describe a case of autoimmune GFAP astrocytopathy with classic clinical and radiographic features as well as presence of eosinophils in the CSF. This case highlights a potential association of eosinophils in the CSF with autoimmune GFAP astrocytopathy, which may suggest its inclusion in the differential diagnosis of eosinophilic meningitis, encephalitis, or myelitis.

Eosinophils-from cradle to grave: An EAACI task force paper on new molecular insights and clinical functions of eosinophils and the clinical effects of targeted eosinophil depletion

Over the past years, eosinophils have become a focus of scientific interest, especially in the context of their recently uncovered functions (e.g. antiviral, anti-inflammatory, regulatory). These versatile cells display both beneficial and detrimental activities under various physiological and pathological conditions. Eosinophils are involved in the pathogenesis of many diseases which can be classified into primary (clonal) and secondary (reactive) disorders and idiopathic (hyper)eosinophilic syndromes. Depending on the biological specimen, the eosinophil count in different body compartments may serve as a biomarker reflecting the underlying pathophysiology and/or activity of distinct diseases and as a therapy-driving (predictive) and monitoring tool. Personalized selection of an appropriate therapeutic strategy directly or indirectly targeting the increased number and/or activity of eosinophils should be based on the understanding of eosinophil homeostasis including their interactions with other immune and non-immune cells within different body compartments. Hence, restoring as well as maintaining homeostasis within an individual's eosinophil pool is a goal of both specific and non-specific eosinophil-targeting therapies. Despite the overall favourable safety profile of the currently available anti-eosinophil biologics, the effect of eosinophil depletion should be monitored from the perspective of possible unwanted consequences.

Prevalence of Angiostrongylus cantonensis in definitive and intermediate hosts collected from agricultural areas in Ampayon, Butuan City, Southern Philippines

Angiostrongyliasis is a parasitic disease and a leading cause of human eosinophilic meningoencephalitis caused by rat lungworm Angiostrongylus cantonensis. This parasite infects a wide range of animal hosts, including snails and rats, which plays a significant role in zoonotic transmission. The study was conducted to determine the prevalence of A. cantonensis infection in freshwater snails and definitive rat hosts in the agricultural area in Ampayon, Butuan City, Philippines. A total of 54 rat samples and 719 snail individuals were collected in June and July 2020. An overall 2.36% prevalence rate of A. cantonensis snail infection was recorded, consisting of Pomacea canaliculata and Melanoides tuberculata, with a prevalence rate of 4.05% and 1.38%, respectively. Results revealed an overall prevalence of 38.9% in rat infection. Rattus tanezumi (48.48%) showed a higher infection than Rattus norvegicus (23.80%). Higher infection rates were found in rice field environments than residential houses, with 44.12% and 30% prevalence rates, respectively. Moreover, male rats showed higher infection rates (50%) than female rats (26.92%). Among age classes, adult rats had significantly higher infection rates (48.57%) than juvenile rats (21.05%). Correlation analysis showed a significant positive correlation between A. cantonensis infection intensity to the body length (r = 0.603; p = 0.001) and body weight (r = 0.715; p = 0.000) of rats. The study exemplifies the critical role of intermediate and definitive hosts for angiostrongyliasis. Infected freshwater snails and rats in rice fields make these agricultural areas a venue for A. cantonensis emergence. Integrated actions, health education campaigns, surveillance, hygiene, and good farming practices will help prevent the potential risk of the transmission of angiostrongyliasis in the area.

IgE antibody responses in cerebrospinal fluids relate to the brain pathologic injury of hosts with Angiostrongylus cantonensis infection

BACKGROUND

The immunoglobulin E (IgE) response to Angiostrongylus cantonensis infection increases in the host. This study analyzed the IgG and IgE responses detected in different body fluids of A. cantonensis-infected mice.

METHODS

BALB/c (high susceptibility), CBA (medium), and C57BL/6 and C57BL/10 (resistance) strain mice were used in this study. The levels of IgM, IgG, and IgE in the serum and cerebrospinal fluid (CSF) from infected mice were compared. A. cantonensis-reactive antigens from BALB/c and C57BL/6 mice CSF were also analyzed.

RESULTS

Antibodies against fifth-stage larvae (L5) antigens increased in mice CSF, particularly IgE, relate to worm rejection and the susceptibility of different mouse strains. The increased IgE level in BALB/c mice CSF is lower than that from others, suggesting IgE response in brain is more important than that in serum. Anti-L5 and anti-excretory/secretory (ES) antigen IgE and IgG responses in CSF were analyzed. In addition, the antibody-dependent eosinophil-mediated cytotoxicity induced by anti-excretory/secretory (ES) antigen antibodies may be the reason of severe brain inflammation in infected BALB/c mice. IgE and IgG antibodies against a 105 kDa protein of L5 antigen was detected at week 3 post-infection in C57BL/6 mice and week 5 post-infection in BALB/c mice. We suggest that 105 kDa protein is related with the antibody response of A. cantonensis-infected mice.

CONCLUSION

We found that IgE antibodies in mice CSF against L5 antigens related to worm rejection in mice brains. This study may help to identify specific angiostrongyliasis markers that can be applied for clinical diagnosis and treatment in future.

Who Let the Dogs Out? Unmasking the Neglected: A Semi-Systematic Review on the Enduring Impact of Toxocariasis, a Prevalent Zoonotic Infection

Toxocariasis remains an important neglected parasitic infection representing one of the most common zoonotic infections caused by the parasite Toxocara canis or, less frequently, by Toxocara cati. The epidemiology of the disease is complex due to its transmission route by accidental ingestion of embryonated Toxocara eggs or larvae from tissues from domestic or wild paratenic hosts. Even though the World Health Organization and Centers for Disease Control classified toxocariasis amongst the top six parasitic infections of priority to public health, global epidemiological data regarding the relationship between seropositivity and toxocariasis is limited. Although the vast majority of the infected individuals remain asymptomatic or experience a mild disease, the infection is associated with important health and socioeconomic consequences, particularly in underprivileged, tropical, and subtropical areas. Toxocariasis is a disease with multiple clinical presentations, which are classified into five distinct forms: the classical visceral larva migrans, ocular toxocariasis, common toxocariasis, covert toxocariasis, and cerebral toxocariasis or neurotoxocariasis. Anthelmintic agents, for example, albendazole or mebendazole, are the recommended treatment, whereas a combination with topical or systemic corticosteroids for specific forms is suggested. Prevention strategies include educational programs, behavioral and hygienic changes, enhancement of the role of veterinarians, and anthelmintic regimens to control active infections.

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.

Rapid Single-Step Immunochromatographic Assay for Angiostrongylus cantonensis Specific Antigen Detection

Angiostrongylus cantonensis is the major etiological nematode parasite causing eosinophilic meningitis and/or eosinophilic meningoencephalitis in humans. The rapid global spread of Angiostrongylus cantonensis and the emerging occurrence of the infection have exposed the shortcomings of traditional/conventional diagnostics. This has spurred efforts to develop faster, simpler and more scalable platforms that can be decentralized for point-of-need laboratory testing. By far, the point-of-care immunoassays such as the lateral flow assay (LFA) are the best-placed. In this work, a LFA in the form of an immunochromatographic test device (designated AcAgQuick^Dx), based on the detection of a circulating Angiostrongylus cantonensis-derived antigen, was established using anti-31 kDa Angiostrongylus cantonensis antibody as the capture reagent and anti-Angiostrongylus cantonensis polyclonal antibody as the indicator reagent. The AcAgQuick^Dx was evaluated for its diagnostic potential with a total of 20 cerebrospinal fluids (CSF) and 105 serum samples from patients with angiostrongyliasis and other clinically related parasitic diseases, as well as serum samples from normal healthy subjects. Three of the ten CSF samples from serologically confirmed angiostrongyliasis cases and two of the five suspected cases with negative anti-Angiostrongylus cantonensis antibodies showed a positive AcAgQuick^Dx reaction. Likewise, the AcAgQuick^Dx was able to detect Angiostrongylus cantonensis specific antigens in four serum samples of the 27 serologically confirmed angiostrongyliasis cases. No positive reaction by AcAgQuick^Dx was observed in any of the CSF (n = 5) and serum (n = 43) samples with other parasitic infections, or the normal healthy controls (n = 35). The AcAgQuick^Dx enabled the rapid detection of active/acute Angiostrongylus cantonensis infection. It is easy to use, can be transported at room temperature and does not require refrigeration for long-term stability over a wide range of climate. It can supplement existing diagnostic tests for neuroangiostrongyliasis under clinical or field environments, particularly in remote and resource-poor areas.

Comparison of Antibody Isotype Response to Angiostrongylus cantonensis in Experimentally Infected Rats (Rattus norvegicus) Using Hawai'i 31 kDa Antigen in an Indirect ELISA

Neuroangiostrongyliasis (NAS) is an emerging tropical disease in humans and some animals which is caused by infection with the parasitic nematode Angiostrongylus cantonensis. It is the leading cause of eosinophilic meningitis worldwide. Diagnoses in humans and susceptible animals are generally presumptive and easily confused with other central nervous system disorders. The 31 kDa antigen is currently the only NAS immunodiagnostic assay that has achieved 100% sensitivity. However, little is known about the humoral immune response against the 31 kDa antigen in NAS infections, which would be critical for widespread adoption of this assay. We used the Hawai'i 31 kDa isolate in an indirect ELISA assay to confirm the presence of immunoglobulin IgG, IgM, IgA, and IgE isotypes in six-week post-infection plasma from lab-reared rats infected with 50 live, third-stage, A. cantonensis larvae isolated from a wild Parmarion martensi semi-slug. Our results confirmed the presence of all four isotypes against the Hawaii 31 kDa isolate, with sensitivity ranging from 22-100%. The IgG isotype showed 100% sensitivity in detecting A. cantonensis infection, which validates the use of IgG indirect ELISA with 31 kDa antigen as an effective immunodiagnostic assay for rats six weeks post-infection. Given each isotype may be present at different times during NAS infections, our data provides preliminary information on the humoral immune response to A. cantonensis infection in lab-reared rats and serves as a baseline for future studies.

Neuroangiostrongyliasis: Updated Provisional Guidelines for Diagnosis and Case Definitions

Angiostrongylus cantonensis is the main causative agent for eosinophilic meningoencephalitis in humans. Larvae are rarely found in the cerebral spinal fluid (CSF). Consequently, serology and DNA detection represent important diagnostic tools. However, interpretation of the results obtained from these tools requires that more extensive accuracy studies be conducted. The aim of the present study is to update guidelines for diagnosis and case definitions of neuroangiostrongyliasis (NA) as provided by a working group of a recently established International Network on Angiostrongyliasis. A literature review, a discussion regarding criteria and diagnostic categories, recommendations issued by health authorities in China and an expert panel in Hawaii (USA), and the experience of Thailand were considered. Classification of NA cases and corresponding criteria are proposed as follows: minor (exposure history, positive serology, and blood eosinophilia); major (headache or other neurological signs or symptoms, CSF eosinophilia); and confirmatory (parasite detection in tissues, ocular chambers, or CSF, or DNA detection by PCR and sequencing). In addition, diagnostic categories or suspected, probable, and confirmatory are proposed. Updated guidelines should improve clinical study design, epidemiological surveillance, and the proper characterization of biological samples. Moreover, the latter will further facilitate accuracy studies of diagnostic tools for NA to provide better detection and treatment.

Management of Rat Lungworm Disease (Neuroangiostrongyliasis) Using Anthelmintics: Recent Updates and Recommendations

While there have been legitimate concerns in the past regarding the use of anthelmintics for the management of neuroangiostrongyliasis (rat lungworm disease), recent studies demonstrate that they can be considered safe and efficacious, particularly albendazole, which is regarded as the choice anthelmintic for its management. However, physician hesitancy to prescribe, as well as problems of availability persist, at least in Hawaii, which is considered the epicenter of this disease in the US. As a result, many patients suffer a diminished quality of life or even death. Here, we discuss recent studies that provide insights into new treatments and preventative interventions, which can be more rigorously used for the management of neuroangiostrongyliasis. In summary, results from recent studies suggest that albendazole and avermectins are beneficial for post-exposure management, pyrantel pamoate is beneficial as a post-exposure prophylactic, and levamisole is deserving of further study for the treatment of neuroangiostrongyliasis.

Eosinophilic Meningitis: Eleven-Year Experience at Texas Children's Hospital

Eosinophilic meningitis can be caused by various etiologies and is reported mostly in tropical climates. The diagnosis is rare in the continental US, presenting challenges for management. Following a case of pediatric eosinophilic meningitis, we reviewed our 11-year experience with this diagnosis at a large US children's hospital.

Parasitism of terrestrial gastropods by medically-important nematodes in Brazil

An ample variety of parasitic associations are found between mollusks and nematodes, in which the mollusks may act as intermediate, paratenic or definitive hosts. Some free-living nematodes, in particular those of the order Rhabditida, are also found frequently in terrestrial mollusks. The present study reviews the results of the parasitological testing on samples of terrestrial mollusks conducted at the Brazilian National Reference Laboratory for Schistosomiasis and Malacology between 2008 and 2021. The samples were supplied primarily by the public health authorities from the different regions of Brazil, but also by research institutions and general population. The mollusks were processed individually and the obtained larvae were identified from their morphology and, whenever necessary, by molecular analysis. A total of 1,919 service orders were registered during the period, including 19,758 mollusk specimens collected from 23 of the 26 Brazilian states, as well as the Federal District, totalizing 145 municipalities. There was a marked predominance of the synanthropic species that are widely distributed in Brazil-Achatina fulica (87.08%), Bulimulus tenuissimus (4.18%), Bradybaena similaris (2.06%), and Sarasinula linguaeformis (1.50%). Of the 16,750 terrestrial mollusks examined, nematodes were recorded in 1,308 service orders, with the predominance of the superfamily Metastrongyloidea, in 616 service orders. They included Angiostrongylus cantonensis, rat lungworm, which was found in 252 samples, and Aelurostrongylus abstrusus in 145 samples. Free-living nematodes were found in 952 samples, Ancylostoma caninum and Cruzia tentaculata (previously identified as Strongyluris sp.) in one and 275 samples, respectively, and other parasites in 210 samples (not identified). The results highlight the diversity of the associations between nematodes and terrestrial mollusks in Brazil, in particular invasive and synanthropic species, with emphasis on the giant African land snail, Achatina fulica. They demonstrate the prominent role of this species of mollusk in the transmission of medically-important nematodes, which affect the health of both humans and animals, in particular eosinophilic meningitis, which is caused by Angiostrongylus cantonensis. This reinforces the need for more studies, and justify the growing demand for information as well as parasitological diagnosis of this mollusk, given its wide distribution in Brazil and its impact as an urban pest.

The application of metagenomic next-generation sequencing for Angiostrongylus eosinophilic meningitis in a pediatric patient: A case report

Background

Angiostrongylus eosinophilic meningitis (AEM) is a rare yet emerging disease caused by Angiostrongylus cantonensis infection. Its atypical symptoms may delay the diagnosis and cause fatal outcomes, especially in the early stages of infection and among children.

Case presentation

Here we reported the use of metagenomic next-generation sequencing (mNGS) to facilitate the diagnosis and treatment of an 8-year-old boy with severe A. cantonensis infection. The mNGS tests consistently identified the infection of A. cantonensis prior to the detection by the immunologic method and confirmed it as AEM. Owing to the multidisciplinary team (MDT)-administrated treatments and close disease monitoring based on regular clinical tests and sequential mNGS tests, the patients eventually fully recovered from severe infectious conditions.

Conclusion

This case demonstrated the advantages of mNGS for early diagnosis of AEM in pediatric patients, highlighting its application for pan-pathogen detection, as well as disease monitoring for severe A. cantonensis infection.

Immunoanalysis of different antigenic preparations of Angiostrongylus cantonensis for neuroangiostrongyliasis diagnosis improvement

BACKGROUND

Angiostrongylus cantonensis is the etiological agent of neuroangiostrongyliasis in humans, which is developed in gastropods and vertebrate species, mainly rodents. Human transmission occurs through consumption of molluscs and paratenic hosts infected with L3, and the migration of larvae to the central nervous system causes eosinophilic meningitis. Laboratory diagnosis is based on molecular and immunological tests, using young or adult females as a source of antigens. However, these tests give positive results only after several weeks of symptoms onset and also cross-reactions with others parasite infections may occur.

OBJECTIVES

The purpose of this work was to study different antigenic preparations of distinct evolutionary phases of A. cantonensis, in order to improve serological techniques for disease immunodiagnosis.

METHODS

For this purpose, antigenic fractions of different evolutionary forms were evaluated by Dot-enzyme-linked immunosorbent assay (Dot-ELISA) and Western blot using serum samples.

FINDINGS

All analysed fractions showed reactivity with serum samples from patients with neuroangiostrongyliasis, especially female membrane alkaline (FAM) and female soluble alkaline (FAS) fractions together with female soluble saline (FSS), improving the technique specificity.

MAIN CONCLUSIONS

The results point to the possibility of use of raw female antigens in association with alkaline membrane antigens extracted from adult worms to aid in diagnosis and helps initiate neuroangiostrongyliasis surveillance and control actions.

Case Report: Cryptococcal eosinophilic meningitis in a patient with Hodgkin lymphoma

Cryptococcal meningitis is the most common fungal meningitis in clinical practice. It primarily occurs in immunocompromised people and is typically associated with human immunodeficiency virus (HIV) infection. In rare cases, it is associated with Hodgkin lymphoma (HL). Eosinophilic meningitis (EM) is characterized by increased eosinophils in the cerebrospinal fluid (CSF) and is often caused by a parasitic infection of the central nervous system (CNS). EM caused by cryptococcal infection is rare; only four cases have been reported in the past 30 years. Here, we report a case of cryptococcal meningitis in a patient with HL who presented with an atypical eosinophil-predominant CSF cytology response. The patient's eosinophil proportion reached 91%; a proportion this high has not been reported previously and may be associated with HL. After antifungal therapy and tumor chemotherapy, the proportion of eosinophils decreased significantly. This case shows that cryptococcal meningitis and HL may be simultaneously contributing to CSF eosinophilia. HL should be considered in patients with eosinophilic cryptococcal meningitis and multiple adenopathies.

Case Report: Angiostrongylus cantonensis Infection Presenting as Small Fiber Neuropathy

Angiostrongylus cantonensis is an emerging parasite that is the most common cause of eosinophilic meningitis worldwide. Human infection typically presents with headache, neck stiffness, and paresthesia. We report a case of a woman with PCR positive A. cantonensis infection who presented with symptoms of small fiber neuropathy (SFN) but no headache. SFN was confirmed by skin biopsy. After failing standard medications for neuropathy, she was treated with intravenous lidocaine with considerable improvement. However, she required medications for 1 year to treat her chronic neuropathy. Infection by A. cantonensis should be added to the list of causes of SFN, and its potential to cause chronic sequelae should be appreciated.

Paratenic hosts of Angiostrongylus cantonensis and their relation to human neuroangiostrongyliasis globally

The nematode parasite Angiostrongylus cantonensis (rat lungworm) has a complex life cycle involving rats (definitive hosts) and gastropods (intermediate hosts), as well as various paratenic hosts. Humans become infected and develop rat lungworm disease (neuroangiostrongyliasis) when they consume intermediate or paratenic hosts containing the infective parasite larvae. This study synthesizes knowledge of paratenic hosts of A. cantonensis and investigates their role in causing human neuroangiostrongyliasis worldwide. A literature review was conducted by searching PubMed, JSTOR and Scopus, pooling additional information from sources accumulated over many years by RHC, and snowball searching. The review identified 138 relevant articles published between 1962 and 2022. Freshwater prawns/shrimp, crayfish, crabs, flatworms, fish, sea snakes, frogs, toads, newts, lizards, centipedes, cattle, pigs and snails were reported to act as paratenic hosts in various regions including South and Southeast Asia, Pacific islands, the USA and the Caribbean, as well as experimentally. Human cases of neuroangiostrongyliasis have been reported from the 1960s onwards, linked, sometimes speculatively, to consumption of freshwater prawns/shrimp, crabs, flatworms, fish, frogs, toads, lizards and centipedes. The potential of paratenic hosts to cause neuroangiostrongyliasis depends on whether they are eaten, how frequently they are consumed, the preparation method, including whether eaten raw or undercooked, and whether they are consumed intentionally or accidentally. It also depends on infection prevalence in the host populations and probably on how high the parasite load is in the consumed hosts. To prevent human infections, it is crucial to interrupt the transmission of rat lungworm to humans, from both intermediate hosts and frequently consumed paratenic hosts, by adhering to safe food preparation protocols. Educating the general public and the medical community about this largely neglected tropical/subtropical disease is key.

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Neuroangiostrongyliasis, an emerging parasitic disease of humans and wildlife.

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Caused by the nematode Angiostrongylus cantonensis (rat lungworm).

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Infection primarily via ingestion of stage 3 larvae of the parasite.

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People eat raw intermediate or paratenic hosts infected with stage 3 larvae.

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Comprehensive review of paratenic hosts’ role in neuroangiostrongyliasis globally.

Extensive myelitis with eosinophilic meningitis after Chimeric antigen receptor T cells therapy

Immune effector cell‐associated neurotoxicity syndrome (ICANS) is a frequent adverse event after Chimeric antigen receptor T cells (CAR‐T cells). A patient treated with anti‐CD19 CAR‐T cells for a refractory mantle cell lymphoma presented at Day 8 post‐infusion with extensive myelitis. Unusual eosinophilia was disclosed in the patient's cerebrospinal fluid. After treatment with methylprednisolone and siltuximab, a decrease in clinical symptoms and magnetic resonance imaging lesions were obtained. This unprecedented presentation of eosinophilic meningitis after CAR‐T cells therapy highlights the need for a better understanding of the physiopathology of ICANS, especially to identify potentially targetable pathways.

Larvicidal Efficacy of Ozone and Ultrasound on Angiostrongylus cantonensis (Rat Lungworm) Third-Stage Larvae

The parasitic nematode Angiostrongylus cantonensis (rat lungworm) is the leading cause of human eosinophilic meningitis worldwide. Most human infections occur through the accidental consumption of A. cantonensis hidden within produce as infectious third-stage larvae (L3), yet little research has been published addressing possible methods to mitigate this means of transmission. Here, we describe our tests of ozone gas—an oxidizing agent—and ultrasound, both used for disinfection of food and municipal water supplies and in industrial cleaning. We found that exposure to ozone, produced using two different commercially available ozone generators over varying durations of time and concentrations, was capable of achieving 100% larval mortality. In addition, we evaluated the impact of different sound frequencies on A. cantonensis L3 survival using two different commercially available ultrasonic cleaners, and found that 60 s of 40 kHz produced 46% mortality within 2 h. The combined use of ultrasound and ozone gas simultaneously resulted in a minimum of 89% normalized mean percent mortality within 2 h of treatment. Our study suggests that both ozone and ultrasound show high larvicidal efficacy, both independently and together, and thus show promise as methods for reducing the risk of rat lungworm infection via accidental consumption.

Eosinophilic meningoencephalitis caused by rat lungworm (Angiostrongylus cantonensis) migration in a white-eared opossum (Didelphis albiventris) with concurrent distemper virus in southern Brazil

Angiostrongylus cantonensis is a worldwide zoonotic parasite that causes eosinophilic meningoencephalitis in many species of animals including humans. This report describes neuro-angiostrongylosis in a white-eared opossum that showed nervous clinical signs such as circling and depression. At necropsy, no relevant macroscopic lesions were observed. Histologically, eosinophilic meningoencephalitis was associated with multiple sections of nematodes and many intracytoplasmic eosinophilic inclusion bodies within gastric parietal cells. Immunohistochemistry was strongly positive for canine distemper virus in the stomach but there was no immunolabeling in the brain. This study describes a fatal case of eosinophilic meningoencephalitis by A. cantonensis with canine distemper virus concurrent infection in a white-eared opossum in southern Brazil, with histological characterization and molecular confirmation of the parasitism.

Eosinophilic meningitis following suboccipital craniotomy without bovine dural graft: illustrative case

BACKGROUND

Eosinophilic meningitis is a rare known complication after brain surgery associated with duraplasty using artificial bovine graft. However, eosinophilic meningitis after craniotomy without bovine dural graft has not been reported.

OBSERVATIONS

A 48-year-old female presented with lateral medullary infarction caused by a vertebral artery dissecting aneurysm incorporating the posterior inferior cerebellar artery (PICA). The authors performed occipital artery–PICA anastomosis and repaired the dura by primary suture without bovine graft. Thereafter, endovascular internal trapping using coils was conducted. Severe headache developed at postoperative day 17, and the patient was diagnosed with eosinophilic meningitis. After administration of a high-dose corticosteroid for 2 weeks, her symptoms and laboratory findings were improved.

LESSONS

Postoperative eosinophilic meningitis is rarely related to craniotomy without using bovine graft. Neurosurgeons should consider the possibility of eosinophilic meningitis after craniotomy without a xenogeneic dural material.

The invasive giant African land snail, Achatina fulica (Gastropoda: Pulmonata): global geographical distribution of this species as host of nematodes of medical and veterinary importance

The giant African land snail, Achatina fulica, is an important invasive species in many countries, where it causes losses in biodiversity and agriculture, as well as impacting the health of both humans and animals, as the intermediate host of medically important nematodes. The present study is based on a comprehensive review of the literature on the nematodes that have been found in association with A. fulica, worldwide. We searched a number of different databases and used the findings to investigate the methods used to extract and identify the nematodes, their larval stages, and environment and collecting procedures of the infected molluscs. Between 1965 and 2021, 11 nematode species were recorded in association with A. fulica in 21 countries. Most of the studies recorded associations between A. fulica and Angiostrongylus cantonensis, which causes cerebral angiostrongyliasis in humans and Aelurostrongylus abstrusus, which provokes pneumonia in felines. The nematodes were extracted primarily by artificial digestion with hydrochloric acid or pepsin, and identified based on their morphology or through experimental infection to obtain the adult. In most cases, the nematodes were at larval stage L3, and the infected A. fulica were collected from anthropogenic environments. The results demonstrate the importance of A. fulica as a host of nematodes of medical and veterinary importance, as well the contribution of anthropogenic environments to the occurrence of the parasites, and give information about the different methods used to collect and identify the nematodes found associated with this species.

Angiostrongylosis in Animals and Humans in Europe

Lungworms in the genus Angiostrongylus cause disease in animals and humans. The spread of Angiostrongylus vasorum within Europe and the recent establishment of Angiostrongylus cantonensis increase the relevance of these species to veterinary and medical practitioners, and to researchers in parasitology, epidemiology, veterinary science and ecology. This review introduces the key members of the genus present in Europe and their impacts on health, and updates the current epidemiological situation. Expansion of A. vasorum from localized pockets to wide distribution across the continent has been confirmed by a rising prevalence in foxes and increasing reports of infection and disease in dogs, while the list of carnivore and mustelid definitive hosts continues to grow. The tropically distributed rat lungworm A. cantonensis, meanwhile, has been recorded on islands south of Europe, previously the Canary Islands, and now also the Balearic Islands, although so far with limited evidence of zoonotic disease. Other members of the genus, namely, A. chabaudi, A. daskalovi and A. dujardini, are native to Europe and mainly infect wildlife, with unknown consequences for populations, although spill-over can occur into domestic animals and those in zoological collections. The epidemiology of angiostrongylosis is complex, and further research is needed on parasite maintenance in sylvatic hosts, and on the roles of ecology, behaviour and genetics in disease emergence. Improved surveillance in animals and humans is also required to support risk assessments and management.

Clinical Efficacy and Safety of Albendazole and Other Benzimidazole Anthelmintics for Rat Lungworm Disease (Neuroangiostrongyliasis): A Systematic Analysis of Clinical Reports and Animal Studies

The safety and efficacy of benzimidazole anthelmintics for the treatment of rat lungworm disease (neuroangiostrongyliasis) have been questioned regardless of numerous experimental animal studies and clinical reports. In this review, 40 of these experimental animal studies and 104 clinical reports are compiled with a focus on albendazole. Among the 144 articles involving an estimated 1034 patients and 2561 animals, 4.1% were inconclusive or vague regarding the use of benzimidazoles. Of the remaining 138 articles, 90.5% found benzimidazoles to be safe and effective (885 patients, 2530 animals), 4.3% as safe but ineffective (73 patients, 3 animals), and 5.0% caused adverse reactions (7 patients, 28 animals). Among those clinical reports that described a confirmed diagnosis of neuroangiostrongyliasis in which albendazole monotherapy was used, 100% reported high efficacy (743 patients, 479 animals). In those where albendazole-corticosteroid co-therapy was used, 97.87% reported it to be effective (323 patients, 130 animals).

The returned traveler with neurologic manifestations: could my patient have a parasite?

PURPOSE OF REVIEW

The present review focuses on parasitic infections of the central nervous system (CNS) that can affect the international traveler.

RECENT FINDINGS

The epidemiology of imported parasitic infections is changing and clinicians are treating increasing numbers of returned travelers with parasitic infections in the CNS with which they are not familiar.

SUMMARY

The epidemiology, life cycle, clinical manifestations, diagnosis, and treatment of parasites that affect the CNS will be discussed.

Approach to Neurologic Infections

PURPOSE OF REVIEW

This article provides an overview of the clinical approach to the diagnosis of neurologic infections, focusing on the symptoms, signs, imaging features, and laboratory findings of the major categories of neuroinfectious diseases.

RECENT FINDINGS

The increased use of immunosuppressive and immunomodulatory therapy to treat autoimmune diseases has led to an increase in opportunistic neurologic infections. The description of numerous causes of autoimmune antibody-mediated encephalitis over the past decade has expanded the differential diagnosis of encephalitis beyond infection. The emergence of metagenomic next-generation sequencing has led to diagnoses of rare or unexpected causes of neurologic infections and has the potential to enhance diagnostic precision in neuroinfectious diseases.

SUMMARY

Infections of the nervous system can affect any level of the neuraxis and present over any time course. Neurologic infections may present atypically with respect to clinical, radiologic, and CSF analysis features in immunocompromised patients or older adults. A thorough evaluation including systemic features, past medical history, travel, exposures, detailed examination, neuroimaging, and CSF analysis is often necessary to make a definitive diagnosis. It is important to be aware of the test characteristics and limitations of microbiological tests on CSF for neurologic infections to avoid being misled by false positives or false negatives.

Genetic Characterization and Detection of Angiostrongylus cantonensis by Molecular Approaches

Angiostrongylus cantonensis constitutes a major etiologic agent of eosinophilic meningoencephalitis. The detection methods for angiostrongyliasis mainly depend on morphology or immunology. A firmer diagnosis could be reached by directly detecting the parasite in the cerebrospinal fluid or through laboratory assays that are specific for Angiostrongylus-induced antibodies or the parasite's DNA. A. cantonensis detection could be carried out by larva release from the tissue upon pepsin digestion. However, the procedure requires live mollusks, which might complicate the analysis of large amounts of samples. Since morphological assays are limited, multiple molecular techniques have been put forward for detecting A. cantonensis, including PCR amplification of targets followed by fragment length or DNA sequence analysis. This allows rapid and accurate identification of A. cantonensis for efficient infection management and epidemiological purposes. In this study, we reviewed the current methods, concepts, and applications of molecular approaches to better understand the genetic characterization, molecular detection methods, and practical application of molecular detection in A. cantonensis.

Eosinophilic Meningitis and Intraocular Infection Caused by Dirofilaria sp. Genotype Hongkong

Eosinophilic meningitis caused by human diroflarial infection is rare. We report a case of eosinophilic meningitis and concomitant intraocular dirofilarial infection in India. Sequencing of the mitochondrial genome identified the worm as Dirofilaria sp. genotype Hongkong, a close relative of D. repens nematodes.

Autochthonous Angiostrongylus cantonensis, Angiostrongylus vasorum and Aelurostrongylus abstrusus infections in native terrestrial gastropods from the Macaronesian Archipelago of Spain

The presence of zoonotic relevant Angiostrongylus cantonensis infections has recently been reported in rat final hosts and gastropod intermediate hosts in Tenerife, Spain. However, data on A. cantonensis, Angiostrongylus vasorum and Aelurostrongylus abstrusus prevalences in endemic gastropods for other islands of the Macaronesian Archipelago are still missing. In order to fill this gap, we conducted an epidemiological study on terrestrial native slug (Plutonia lamarckii) and snail (Cornu aspersum, Theba pisana, Rumina decollata) species in 27 selected locations of Tenerife, Gran Canaria, El Hierro, Lanzarote, La Palma and Fuerteventura. Overall, 131 terrestrial gastropods were collected in winter/spring season 2018/2019 and examined for the presence of metastrongyloid lungworm larvae via artificial digestion. The current data revealed a total prevalence of 4.6% for A. vasorum, 3.8% for A. abstrusus and 0.8% for A. cantonensis. In Tenerife, three lungworm species were detected, thereby re-confirming A. cantonensis endemicity for this island. Prevalences of snails (C. aspersum) originating from El Hierro were 5% for A. abstrusus and 15% for A. vasorum, respectively, with larval burdens up to 290 larvae per specimen. This epidemiological study indicates the presence of human, canine and feline lungworm species in Macaronesia, Spain. The current data-particularly those on anthropozoonotic A. cantonensis-call for a regular large-scale monitoring on intermediate hosts, paratenic hosts and definitive hosts to prevent further spread of lungworm-related diseases in humans and animals.

Infectious Causes of Eosinophilic Meningitis in Korean Patients: A Single-Institution Retrospective Chart Review from 2004 to 2018

Eosinophilic meningitis is defined as the presence of more than 10 eosinophils per μl in the cerebrospinal fluid (CSF), or eosinophils accounting for more than 10% of CSF leukocytes in patients with acute meningitis. Parasites are the most common cause of eosinophilic meningitis worldwide, but there is limited research on patients in Korea. Patients diagnosed with eosinophilic meningitis between January 2004 and June 2018 at a tertiary hospital in Seoul, Korea were retrospectively reviewed. The etiology and clinical characteristics of each patient were identified. Of the 22 patients included in the study, 11 (50%) had parasitic causes, of whom 8 (36%) were diagnosed as neurocysticercosis and 3 (14%) as Toxocara meningitis. Four (18%) patients were diagnosed with fungal meningitis, and underlying immunodeficiency was found in 2 of these patients. The etiology of another 4 (18%) patients was suspected to be tuberculosis, which is endemic in Korea. Viral and bacterial meningitis were relatively rare causes of eosinophilic meningitis, accounting for 2 (9%) and 1 (5%) patients, respectively. One patient with neurocysticercosis and 1 patient with fungal meningitis died, and 5 (23%) had neurologic sequelae. Parasite infections, especially neurocysticercosis and toxocariasis, were the most common cause of eosinophilic meningitis in Korean patients. Fungal meningitis, while relatively rare, is often aggressive and must be considered when searching for the cause of eosinophilic meningitis.

De novo transcriptome reveals blood coagulation/antithrombin factors and infection mechanisms in Angiostrongylus cantonensis adult worms

Angiostrongylus cantonensis is the main aetiological agent of eosinophilic meningoencephalitis in humans. Several outbreaks have been documented around the world, cementing its status as an emerging global public health concern. As a result, new strategies for the diagnosis, prophylaxis and treatment of cerebral angiostrongyliasis are urgently needed. In this study, we report on the de novo assembly of the A. cantonensis transcriptome, its full functional annotation and a reconstruction of complete metabolic pathways. All results are available at AngiostrongylusDB (http://angiostrongylus.lad.pucrs.br/admin/welcome). The aim of this study was to identify the active genes and metabolic pathways involved in the mechanisms of infection and survival inside Rattus norvegicus. Among 389 metabolic mapped pathways, the blood coagulation/antithrombin pathways of heparan sulphate/heparin are highlighted. Moreover, we identified genes codified to GP63 (leishmanolysin), CALR (calreticulin), ACE (peptidyl-dipeptidase A), myoglobin and vWD (von Willebrand factor type D domain protein) involved in the infection invasion and survival of the parasite. The large dataset of functional annotations provided and the full-length transcripts identified in this research may facilitate future functional genomics studies and provides a basis for the development of new techniques for the diagnosis, prevention and treatment of cerebral angiostrongyliasis.

In vitro efficacy of anthelmintics on Angiostrongylus cantonensis L3 larvae

Angiostrongylus cantonensis is the leading cause of eosinophilic meningitis worldwide, with life-threatening complications if not managed correctly. Previous in vitro studies have utilized change in motility patterns of adult female worms to assess the efficacy of anthelmintics qualitatively. However, it is the third stage larvae (L3) that are infectious to humans. With differential staining using propidium iodide penetration as the indicator of death, we can distinguish between dead and live larvae. This assay has enabled us to quantify the in vitro efficacy of nine clinically established anthelmintics on A. cantonensis L3. All drugs were tested at a 1 mm concentration. Piperazine and niclosamide were ineffective in inducing larval death; however, albendazole sulfoxide, pyrantel pamoate, diethylcarbamazine, levamisole and praziquantel were effective as compared to unexposed controls (P < 0.05). Ivermectin and moxidectin did not induce significant levels of mortality, but they considerably reduced larval motility almost immediately. This study indicates the need for further in vivo studies to determine the optimal dose and time frame for post-infection treatment with anthelmintics that demonstrated efficacy.

Variation in Angiostrongylus cantonensis infection in definitive and intermediate hosts in Hawaii, a global hotspot of rat lungworm disease

Angiostrongylus cantonensis (rat lungworm) is a tropical and subtropical parasitic nematode, with infections in humans causing angiostrongyliasis (rat lungworm disease), characterized by eosinophilic meningitis. Hawaii has been identified as a global hotspot of infection, with recent reports of high infection rates in humans, as well as rat definitive and snail intermediate hosts. This study investigated variation in A. cantonensis infection, both prevalence and intensity, in wild populations of two species of rats (Rattus exulans and R. rattus) and one species of snail (Parmarion martensi). An overall infection prevalence of 86.2% was observed in P. martensi and 63.8% in rats, with R. exulans (77.4%) greater than R. rattus (47.6%). We found infections to vary with environmental and host-related factors. Body mass was a strong predictor of infection in all three species, with different patterns seen between sexes and species of rats. Infection prevalence and intensity for R. exulans were high in May 2018 and again in February 2019, but generally lower and more variable during the intervening months. Information on sources of variability of infection in wild host populations will be a crucial component in predicting the effectiveness of future disease surveillance or targeted management strategies.

Sandwich dot-immunogold filtration assay (DIGFA) for specific immunodiagnosis of active neuroangiostrongyliasis

Serological tests may yield false-negative results for specific antibodies detection before or at the early seroconversion phase. Tests that detect circulating antigens of Angiostrongylus cantonensis would therefore be of value in diagnosis to distinguish current or past infection. Here, a quick, easy to perform, portable and inexpensive diagnostic device for detection of 31-kDa A. cantonensis specific antigens had been developed. This sandwich dot-immunogold filtration assay (AcDIGFAAg), for detecting active angiostrongyliasis was produced using anti-A. cantonensis polyclonal antibody dotted on the nitrocellulose membrane as a capture agent and colloidal gold-labelled anti-31 kDa A. cantonensis antibody as a detection agent. A well-defined pink dot, indicating positivity, was seen readily by naked eye within 10-15 min. The AcDIGFAAg detected A. cantonensis-specific antigens in cerebrospinal fluid samples from 4 out of 10 serologically confirmed angiostrongyliasis cases and 2 out of 5 suspected cases with negative anti-A. cantonensis antibodies. Among the 19 patient sera with A. cantonensis infection, 2 showed positive reaction by AcDIGFAAg. No positive AcDIGFAAg reaction was observed in all the serum samples with other parasitic diseases, and the healthy controls. The present 'AcDIGFAAg' enables rapid qualitative detection of the specific 31-kDa antigens of A. cantonensis in clinical samples with potential for application even under resource-limited settings.

In vitro comparison of treatments and commercially available solutions on mortality of Angiostrongylus cantonensis third-stage larvae

On Hawai'i Island, an increase in human neuroangiostrongyliasis cases has been primarily associated with the accidental ingestion of Angiostrongylus cantonensis L3 in snails or slugs, or potentially, from larvae left behind in the slug's slime or feces. We evaluated more than 40 different treatments in vitro for their ability to kill A. cantonensis larvae with the goal of identifying a safe and effective fruit and vegetable wash in order to reduce the risk of exposure. Our evaluation of treatment lethality was carried out in two phases; initially using motility as an indicator of larval survival after treatment, followed by the development and application of a propidium iodide staining assay to document larval mortality. Treatments tested included common household products, consumer vegetable washes and agricultural crop washes. We found minimal larvicidal efficacy among consumer-grade fruit and vegetable washes, nor among botanical extracts such as those from ginger or garlic, nor acid solutions such as vinegar. Alkaline solutions, on the other hand, as well as oxidizers such as bleach and chlorine dioxide, did show larvicidal potential. Surfactants, a frequent ingredient in detergents that lowers surface tension, had variable results, but dodecylbenzene sulfonic acid as a 70% w/w solution in 2-propanol was very effective, both in terms of the speed and the thoroughness with which it killed A. cantonensis L3 nematodes. Thus, our results suggest promising directions for future investigation.

Angiostrongylus spp. (Nematoda; Metastrongyloidea) of global public health importance

Human angiostrongyliasis is an important foodborne zoonosis, caused by the infection with Angiostrongylus costaricensis and Angiostrongylus cantonensis. These two species have a significant public health impact in different areas of the world. Angiostrongyliasis is re-emerging and expanding to urban settings rising significant concerns regarding the control of these infections. This review focuses on aspects such as life cycle, epidemiology, clinical manifestations, diagnostics, food safety and control of illness caused especially by A. cantonensis.

Identification of cross-reactive markers to strengthen the development of immunodiagnostic methods for angiostrongyliasis and other parasitic infections

Angiostrongylus cantonensis is the main causative agent of eosinophilic meningoencephalitis (EoM) in humans. Molecular diagnostic methods are essential since the identification of larvae in cerebrospinal fluid (CSF) is extremely rare. To date, the detection of a 31 kDa antigen by Western blotting has been the primary immunodiagnostic method for EoM caused by A. cantonensis. However, cross-reactivity with other parasites has been observed. Therefore, we conducted a comparative analysis using sera from individuals with angiostrongyliasis. We also characterized proteins isolated from different cellular sources of A. cantonensis, Toxocara canis, Schistosoma mansoni, and Strongyloides stercoralis with mass spectrometry. A total of 115 cross-reactive proteins were identified. Three of these proteins, heat shock protein, an intermediate filament protein, and galectin 1, represent potential markers for cross-reactivity. In addition, synthetic peptides were generated from previously identified diagnostic targets and tested against sera from individuals infected with several other parasites. As a result, two other markers of cross-reactivity were identified: peptide #4 derived from the 14-3-3 protein and peptide #12 derived from the Lec-5 protein. In contrast, 34 proteins were exclusively present in the Angiostrongylus extracts and represent promising diagnostic molecules for specific identification of A. cantonensis infection. In particular, cytochrome oxidase subunit I is of great interest as a possible immunodiagnostic target for angiostrongyliasis.

Demographics of the semi-slug Parmarion martensi, an intermediate host for Angiostrongylus cantonensis in Hawai'i, during laboratory rearing

The semi-slug, Parmarion martensi, is an intermediate host of the zoonotic nematode, Angiostrongylus cantonensis, the aetiological agent of neuroangiostrongyliasis or rat lungworm disease in humans. Rearing methods were developed for P. martensi to facilitate studies on nematode transmission and control. Parmarion martensi exhibited high survivorship when reared on a diet of dog food and fresh fruits and vegetables in temperature-controlled cabinets at 21.4°C, 98% relative humidity and 12:12 L:D cycle. Rearing containers were lined with moist paper towels for substrate and plastic pots were provided for hiding/resting and egg-laying. Under these conditions, time to first reproduction was 165.3 ± 12.3 days, fecundity was approximately 34.5 ± 7.8 eggs per adult, and hatch rate was 52.7 ± 3.2%. Survivorship post egg hatch was 86.2 ± 2.9% at 30 days (neonates had a mortality rate of about 14%) and 99% thereafter for up to a year. The demographics of laboratory-reared and wild-caught P. martensi were similar except for the weight of reproductive adults, which was significantly higher in laboratory-reared adults (4.0 ± 0.2 g) than in field-collected adults (1.5 ± 0.1 g).