Treatment of angiostrongyliasis

Benzaldehyde stimulates autophagy via the sonic hedgehog signaling pathway in mouse brain astrocytes after treatment with Angiostrongylus cantonensis excretory-secretory products

Autophagy is a vital cellular process responsible for digesting various cytoplasmic organelles. This process plays a crucial role in maintaining cell survival and homeostasis, especially under conditions that cause nutrient deficiency, cellular damage, and oxidative stress. Neuroangiostrongyliasis is an infection caused by the parasitic nematode Angiostrongylus cantonensis and is considered as an emerging disease in many parts of the world. However, effective therapeutic strategies for neuroangiostrongyliasis still need to be further developed. In this study, we investigated the effects of benzaldehyde treatment on autophagy and sonic hedgehog (Shh) signaling in A. cantonensis-infected mice and its mechanisms. First, we found autophagosome generation in the central nervous system after A. cantonensis infection. Next, benzaldehyde combined with albendazole treatment reduced eosinophilic meningitis and upregulated the expression of Shh signaling- and autophagy-related molecules in A. cantonensis-infected mouse brains. In vitro experiments demonstrated that benzaldehyde could induce autophagy via the Shh signaling pathway in A. cantonensis excretory-secretory products (ESPs)-treated mouse astrocytes. Finally, benzaldehyde treatment also decreased lipid droplet accumulation and increased cholesterol production by activating the Shh pathway after ESPs treatment. In conclusion, these findings suggested that benzaldehyde treatment could alleviate brain damage by stimulating autophagy generation through the Shh signaling pathway.

Angiostrongylus cantonensis induces energy imbalance and dyskinesia in mice by reducing the expression of melanin-concentrating hormone

BACKGROUND

Infection with Angiostrongylus cantonensis (AC) in humans or mice can lead to severe eosinophilic meningitis or encephalitis, resulting in various neurological impairments. Developing effective neuroprotective drugs to improve the quality of life in affected individuals is critical.

METHODS

We conducted a Gene Ontology enrichment analysis on microarray gene expression (GSE159486) in the brains of AC-infected mice. The expression levels of melanin-concentrating hormone (MCH) were confirmed through real-time quantitative PCR (RT-qPCR) and immunofluorescence. Metabolic parameters were assessed using indirect calorimetry, and mice's energy metabolism was evaluated via pathological hematoxylin and eosin (H&E) staining, serum biochemical assays, and immunohistochemistry. Behavioral tests assessed cognitive and motor functions. Western blotting was used to measure the expression of synapse-related proteins. Mice were supplemented with MCH via nasal administration.

RESULTS

Postinfection, a marked decrease in Pmch expression and the encoded MCH was observed. Infected mice exhibited significant weight loss, extensive consumption of sugar and white fat tissue, reduced movement distance, and decreased speed, compared with the control group. Notably, nasal administration of MCH countered the energy imbalance and dyskinesia caused by AC infection, enhancing survival rates. MCH treatment also increased the expression level of postsynaptic density protein 95 (PSD95) and microtubule-associated protein-2 (MAP2), as well as upregulated transcription level of B cell leukemia/lymphoma 2 (Bcl2) in the cortex.

CONCLUSIONS

Our findings suggest that MCH improves dyskinesia by reducing loss of synaptic proteins, indicating its potential as a therapeutic agent for AC infection.

Concurrent infection of Exophiala dermatitidis and Angiostrongylus cantonensis in central nervous system of a child with inherited CARD9 deficiency: A case report and literature review

Exophiala dermatitidis is a relatively common environmental black yeast with a worldwide distribution that rarely causes fungal infection. Here, we report a case of a 6-year-old girl with central nervous system (CNS) encephalitis caused by E. dermatitidis and Angiostrongylus cantonensis. E. dermatitidis was identified by both cerebrospinal fluid culture and metagenomic next-generation sequencing (mNGS). Angiostrongylus cantonensis infection was confirmed by an enzyme linked immunosorbent assay (ELISA). Whole exome sequencing showed that this previously healthy girl carried a homozygous CARD9 mutation for c.820dupG (p.D274Gfs*61) that underlies invasive fungal and parasite infections. We chose glucocortieoid pulse therapy and anti-infective therapy based on the initial results of laboratory examination and cranial MRI images. With the aggravation of the disease and the evidence of the subsequent etiologic test, the combination of antifungal antiparasitic treatments (voriconazole, fluorocytosine and amphotericin B) were actively used. Unfortunately, the girl finally died due to severe systemic infection. mNGS performs a potential value for diagnosing rare CNS infections, and autosomal recessive CARD9 deficiency should be considered in patient with fatal invasive fungal infections.

Clinical Characteristics and Treatment Outcome of Eosinophilic Meningoencephalitis in South Indian Children: Experience From a Prospective Registry

BACKGROUND

To describe the clinical features and therapeutic outcomes of a prospective cohort of children with eosinophilic meningoencephalitis.

METHODS

Children admitted with clinical features suggestive of meningitis along with cerebrospinal fluid (CSF) eosinophilia during the period of 14 years (2008 to 2021) were included. Their baseline characteristics, epidemiologic associations, and treatment outcomes were analyzed and compared with the previous studies.

RESULTS

We identified 25 children (13 males) satisfying the inclusion criteria. The median age at presentation was 3.9 years (range 0.8 to 17 years); 68% were aged less than two years. Fourteen (56%) children had a history of exposure to snails. Most of them presented with fever, headache, irritability, lateral rectus palsy, and early papilledema. Symptoms started three to 42 days (median duration: 14 days) before admission to our center. All children had peripheral eosinophilia, which ranged from 9% to 41%. The mean CSF white blood cell count was 416/mm3 (range 50 to 1245 cells/mm3) with CSF eosinophilia ranging from 11% to 80%. Brain magnetic resonance imaging was done in 24 children and was normal in 15 (62.5%). Leptomeningeal enhancement was seen in two (8.3%) children, and other nonspecific changes were noted in seven (29.1%) children. All children recovered without any neurological deficits with a standard treatment regimen of albendazole and oral steroids. All were asymptomatic at the last follow-up. None of them had any recurrence during the follow-up period.

CONCLUSION

We report one of the largest clinical series of children with eosinophilic meningoencephalitis from an endemic area of South India.

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.

Transmission sources and severe rat lung worm diseases in travelers: a scoping review

BACKGROUND

Rat lung worm disease (RLWD) has several clinical forms including eosinophilic meningitis (EOM) and two severe forms, eosinophilic meningoencephalitis (EOME) and eosinophilic radiculomyelitis (EORM). It remains unclear whether transmission sources are associated with severe forms of RLWD. This study aimed to evaluate if transmission factors are related to the severity of RLWD among travelers by using a scoping review of case reports.

METHODS

This was a review using five databases to retrieve case reports and case series of travelers with RLWD. Clinical data and transmission sources of reported cases diagnosed as RLWD were retrieved. The outcome of the study was occurrence of severe forms of RLWD defined as EOME, EORM, and combined EOME/EORM.

RESULTS

We retrieved 1,326 articles from five databases and 31 articles were included in the analysis. There were 84 cases eligible from 15 countries. Four cases were excluded. Seventy cases were in EOM group and 10 cases had EOME or EORM. Compared with the EOM group, the EOME, EORM, and combination EOME/EORM group had similar age, sex, and risk factors of consumptions of apple snails, shrimp and prawn, and salad/vegetables. The EOME group had higher proportion of consumption of African snails than the EOM group (60% vs 13.8%). However, only one study reported the consumption of African snails and the heterogeneity between studies and the small sample size impeded direct comparisons between groups.

CONCLUSIONS

RLWD in travelers can be found in most continents and mostly get infected from endemic countries of RLWD. Further studies are required to evaluate the association between transmission vectors and severity of RLWD.

Eosinophilic meningitis epidemiological data from a national database in Thailand's Department of Disease Control: a pragmatic, retrospective analytical study

Background

Eosinophilic meningitis (EOM) is a rare neurological disease that can be misdiagnosed or underdiagnosed. Based on reported cases in the literature, there have been 2,827 cases worldwide since 1945. There are limited data on the prevalence and trends of EOM in a real-world setting, even in Thailand, the country with the highest prevalence of EOM. Therefore, this study aimed to evaluate the prevalence of EOM and EOM epidemiological data in a real-world setting.

Methods

This was a pragmatic, retrospective analytical study using a national database. We retrieved EOM epidemiological data reported from government hospitals to Thailand’s Bureau of Epidemiology, within the Ministry of Public Health’s Department of Disease Control (DDC), between 2014 and 2019. The study was conducted by retrieving the data of all patients diagnosed with EOM and reported to the DDC. Diagnosis of EOM is made clinically by evidence of eosinophils of 10% or more of the total white blood cells in cerebrospinal fluid. Details of each patient were retrieved from the 506 Report Form, including age, month of reported case, zone of country, occupation, and mortality. Data regarding infection rate in each year and each zone were reported in rate/100,000 population, while data regarding age, month of reported case, and occupation were reported by year. Differences between means of age group, month of reported case, and occupation were tested by one-way analysis of variance (ANOVA). For those factors with significant differences among groups, Bonferroni method was used to compute pairwise differences.

Results

There were 1,083 EOM cases reported in Thailand during the six-year study period. The average annual incidence of EOM was 180.5 cases, or 0.27 cases/100,000 population. The northeast zone had the highest rate, with 0.89/100,000 population. The common age groups were 25–54 years, with the highest rate among the 35–44 age group, with a mean of 38.3 persons/year. These age groups were significantly different from other age groups (F value 39.23; p < 0.001). A relatively high cumulative monthly incidence (> 100 cases) was seen in four months, including January (117 cases), September (103 cases), October (112 cases), and November (103 cases), though these rates were not significantly different from the other months’ rates. Regarding occupation, the top two occupations with EOM diagnoses were farmers and laborers, which were significantly different from other occupations (F value 99.95; p < 0.001). There was no reported case of death during the study period.

Conclusion

EOM is common in Northeast Thailand among people of working age. The disease can be found throughout the year but is more common in the last quarter of the year. Farmers and laborers have the highest infection rate. To better understand the burden and outcomes of EOM, a national EOM reporting system with a better reporting form is required in endemic countries. Such a report form should include more details on risk exposure, symptoms, signs, treatment, and outcomes.

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.

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.

Verminous meningoencephalomyelitis in a red kangaroo associated with Angiostrongylus cantonensis infection

Angiostrongylus cantonensis is a zoonotic parasitic helminth that normally resides in the pulmonary arteries and the right ventricle of rats (Rattus sp.), the definitive host, where it causes little disease. Humans, dogs, opossums, and various zoo animals are "accidental" hosts. Here we report verminous meningoencephalomyelitis caused by A. cantonensis in a 9-mo-old male red kangaroo (Macropus rufus). The kangaroo was first presented lethargic, recumbent, and hypothermic, with severe muscle wasting. Within 3 wk, he progressed to non-ambulatory paraparesis and died. Gross examination revealed multifocal areas of dark-brown discoloration, malacia, and cavitation in the brain and the spinal cord. Histologically, there were several sections of nematodes surrounded by extensive areas of rarefaction, hemorrhage, spongiosis, neuronal necrosis, and gliosis. Based on size, morphology, and organ location, the nematodes were identified as subadult males and females. Interestingly, an eosinophilic response was largely absent, and the inflammatory response was minimal. A. cantonensis infection had not been reported previously in a red kangaroo in Louisiana or Mississippi, to our knowledge. Our case reaffirms the widespread presence of the helminth in the southeastern United States and indicates that A. cantonensis should be considered as a differential in macropods with neurologic clinical signs in regions where A. cantonensis is now endemic.

Abdominal angiostrongyliasis in the Americas: fifty years since the discovery of a new metastrongylid species, Angiostrongylus costaricensis

Angiostrongylus costaricensis is a zoonotic parasitic nematode described for the first time in 1971 by Pedro Morera and Rodolfo Céspedes in Costa Rica. This parasite causes an infection known as abdominal angiostrongyliasis, affecting mainly school-aged children and young adults. Infection with A. costaricensis has been associated with a myriad of rodent and mollusk species in the Americas and the Caribbean, as its natural hosts and reservoirs. In this commemorative review, we highlight the extensive research collected through a 50-year journey, which includes ecological, pathological, and molecular studies on A. costaricensis and its implicated disease. We also identify major knowledge gaps in its evolutionary history, the ecological role of imported and invasive mollusk species, and immune response. We propose that the advent of -omics analyses will allow us to gather novel information regarding A. costaricensis biology and infection dynamics, as well as to promote the design of much-needed sensitive and specific diagnostic tools.

Eosinophilic Meningitis due to Angiostrongylus cantonensis in Children

Meningoencephalitis is not a rare disease in children. However, eosinophilic meningitis due to Angiostrongylus cantonensis is unusual in the pediatric population. We describe the case of a 12-year-old girl from the central area of Vietnam with eosinophilic meningitis due to A. cantonensis. The patient lived in a rural area, where farming is widespread, and presented with fever and headache. Laboratory results showed peripheral eosinophilia, a cerebrospinal fluid white blood cell count of 730/mm³ with 65% eosinophils. Cerebrospinal fluid ELISA was positive for A. cantonensis, and blood ELISA was positive for A. cantonensis. The presentation was consistent with a diagnosis of A. cantonensis eosinophilic meningitis. The patient recovered fully after administration of albendazole (200 mg/day for 2 weeks), as well as intravenous dexamethasone (0.6 mg/kg/day every 8 h) and mannitol (1.5 g/kg/day every 8 h) for the first 3 days, followed by 5 days of oral prednisolone (2 mg/kg/day).

Tetraventricular Hydrocephalus Following Eosinophilic Meningitis due to Angiostrongylus cantonensis in a 14-Month-Old Boy From Mayotte: A Case Report

Angiostrongylus cantonensis is endemic in Mayotte, and cases of meningitis due to angiostrongyliasis are regularly diagnosed in young children. In a 14-month-old boy with slow-onset psychomotor regression, brain magnetic resonance imaging revealed communicating hydrocephalus. Reverse transcription polymerase chain reaction for A. cantonensis on cerebrospinal fluid was positive. The evolution was favorable with repeated lumbar punctures and a 2-week treatment with albendazole and high-dose corticosteroids.

3-Hydroxybenzaldehyde and 4-Hydroxybenzaldehyde enhance survival of mouse astrocytes treated with Angiostrongylus cantonensis young adults excretory/secretory products

Background

Methods

Results

Conclusions

Clinical features and course of Angiostrongylus cantonensis eosinophilic meningitis in patients receiving supportive therapy

Acute severe headache is the main presentation of eosinophilic meningitis (EOM) caused by Angiostrongylus cantonensis. Oral corticosteroid treatment is effective in reduction of duration of headache but may be contraindicated in particular patients. This study investigated clinical features and clinical course of eosinophilic meningitis caused by A. cantonensis if left untreated. Additionally, factors associated with duration of headache were evaluated. We conducted a retrospective study between 1997 and 2019 at a university hospital in Thailand. The inclusion criteria were adult patients who were diagnosed with EOM, had a positive serological test for A. cantonensis, received only supportive treatment, and had the complete clinical course documented. Factors associated with duration of headache were executed by multivariate linear regression analysis. A total of 54 patients were used in the final analysis. Of those, 39 patients (79.2%) were male and the mean ± SD age of all patients was 33.7 ± 12.2. The mean ± SD duration of headache was 16.0 ± 12.4 days with the longest duration of 49 days. The only factor associated with duration of headache was gender (p = 0.036). The male gender had a coefficient of −8.4 (95% CI: −16.2, −0.6). The median duration of headache in male and female patients was 11 and 20 days, respectively. In conclusion, A. cantonensis eosinophilic meningitis can cause long lasting headache, and gender may be associated with duration of headache.

Guidelines for the diagnosis and treatment of neuroangiostrongyliasis: updated recommendations

A subcommittee of the Hawaii Governor's Joint Task Force on Rat Lungworm Disease developed preliminary guidelines for the diagnosis and treatment of neuroangiostrongyliasis (NAS) in 2018 (Guidelines, 2018). This paper reviews the main points of those guidelines and provides updates in areas where our understanding of the disease has increased. The diagnosis of NAS is described, including confirmation of infection by real-time polymerase chain reaction (RTi-PCR) to detect parasite DNA in the central nervous system (CNS). The treatment literature is reviewed with recommendations for the use of corticosteroids and the anthelminthic drug albendazole. Long-term sequelae of NAS are discussed and recommendations for future research are proposed.

Eosinophilic meningitis outbreak related to religious practice

Three patients with eosinophilic meningitis (EoM) were investigated in two hospitals in Porto Alegre, Southern Brazil. These patients had a common exposure after the ingestion of raw mollusks in a religious ritual. Two of them had an uncommon presentation with intense lower distal extremities pain and small fiber neuropathy as defined by an electroneuromyography (ENMG) study. All three patients were positive for Angiostrongylus cantonensis serology and recovered after antihelminthic and anti-inflammatory treatment. Increased awareness of A. cantonensis infection is important to avoid new infections and to improved recognition and handling of cerebral angiostrongyliasis.

An ecological study of eosinophilic meningitis caused by the nematode, Angiostrongylus cantonensis (Chen, 1935) (Nematoda: Metastrongylidae)

Climate change and other weather factors are associated with several infectious diseases, but are rarely reported as being associated with nematode infection. Eosinophilic meningitis (EOM) is an emerging disease worldwide caused by the nematode, Angiostrongylus cantonensis. It is transmitted through various agents such as snails and slugs. Temperature and rainfall are associated with snail population. There have been no previous studies on the relationship between weather and EOM. This was an ecological study. Numbers of EOM patients and weather data in Thailand's Loei province from 2006 to 2017 were obtained using a national database. A Spearman correlation was used to explore the relationship between EOM and weather variables. We developed a Poisson time series model combined with a distributed lag model (DLM) for estimating the effects of weather on EOM. We also created an autoregressive integrated moving average with exogeneous variable (ARIMAX) model for predicting future EOM cases over the following 12 months. There were 1126 EOM patients in the study. Among several weather factors, wind was significantly negatively correlated with the number of EOM patients (r_s: -0.204, 95% CI: -0.361 to -0.058; p value: 0.014). The ARIMAX(3, 0, 0) model with wind speed as a variable was appropriate for predicting the number of EOM patients. The predicted and actual numbers of EOM patients in 2018 were highly concordant. In conclusion, wind speed is significantly negatively correlated with the number of EOM patients.

Severe CNS angiostrongyliasis in a young marine: a case report and literature review

Angiostrongylus cantonensis is the most common cause of eosinophilic meningitis worldwide. Infection typically occurs through ingestion of undercooked molluscs or vegetables contaminated by infective larvae. Endemic regions were previously limited to southeast Asia and the Pacific basin; however, this parasite is seeing an alarming increase in global distribution with reported cases in more than 30 countries, including several states in the USA. Although infection typically results in meningitis, a broad spectrum of CNS involvement and severity is emerging as diagnostic methods (such as real-time PCR) continue to improve diagnosis. In this Grand Round, we report a case of a 20-year-old active duty US marine serving in Okinawa, Japan, afflicted with severe CNS angiostrongyliasis marked by radiculomyelitis with quadriparesis, hyperaesthesia, and urinary retention. We present this case to highlight that no clear guidelines exist for the treatment of severe CNS angiostrongyliasis and provide our consensus recommendation that treatment algorithms include use of dual corticosteroids plus anthelmintics when radicular symptoms are present. In this Grand Round we review the clinical features, epidemiology, advances to diagnostic techniques, and available data on current treatment options for CNS angiostrongyliasis. This diagnosis should be highly considered in the differential diagnosis of a patient presenting with meningeal symptoms, paraesthesia or hyperaesthesia, and CSF eosinophilia so that treatment can be started early, which is particularly important in children, because of their increased risk of severe disease and mortality. We recommend combined therapy with albendazole and prednisolone, with consideration for increased steroid dosing in severe cases.

Eosinophilic meningitis caused by Angiostrongylus cantonensis in an infant: A case report

RATIONALE

Parasitic eosinophilic meningitis is rarely observed in infants. The diagnosis of this disease is complicated by its atypical and severe clinical manifestations.

PATIENT CONCERNS

An infant presented to our hospital with high fever and irritability, as well as refusal to walk. Cerebrospinal fluid collected through lumbar puncture showed increased eosinophil count and third-stage Angiostrongylus cantonensis larvae.

DIAGNOSES

Eosinophilic meningitis was suspected.

INTERVENTIONS

We started empiric treatment with levamisole (14 mg bid, 2.5 mg/kg·day) and prednisone (17.5 mg qd, 1.5 mg/kg·day).

OUTCOMES

All of the infant's symptoms were resolved approximately 72 hours after treatment. The patient fully recovered from her illness after completing 4 weeks of levamisole and prednisolone treatment.

LESSONS

A. cantonensis is the most common cause of parasitic eosinophilic meningitis cases in Southeast Asia. Physicians treating infants who live in areas where A. cantonensis is endemic and who present with irritability, abnormal motor function, and elevated eosinophil count should be aware of the disease to provide timely and rational therapy to the patients.

Angiostrongylus cantonensis: a review of its distribution, molecular biology and clinical significance as a human pathogen

Angiostrongylus cantonensis is a metastrongyloid nematode found widely in the Asia-Pacific region, and the aetiological agent of angiostrongyliasis; a disease characterized by eosinophilic meningitis. Rattus rats are definitive hosts of A. cantonensis, while intermediate hosts include terrestrial and aquatic molluscs. Humans are dead-end hosts that usually become infected upon ingestion of infected molluscs. A presumptive diagnosis is often made based on clinical features, a history of mollusc consumption, eosinophilic pleocytosis in cerebral spinal fluid, and advanced imaging such as computed tomography. Serological tests are available for angiostrongyliasis, though many tests are still under development. While there is no treatment consensus, therapy often includes a combination of anthelmintics and corticosteroids. Angiostrongyliasis is relatively rare, but is often associated with morbidity and sometimes mortality. Recent reports suggest the parasites' range is increasing, leading to fatalities in regions previously considered Angiostrongylus-free, and sometimes, delayed diagnosis in newly invaded regions. Increased awareness of angiostrongyliasis would facilitate rapid diagnosis and improved clinical outcomes. This paper summarizes knowledge on the parasites' life cycle, clinical aspects and epidemiology. The molecular biology of Angiostrongylus spp. is also discussed. Attention is paid to the significance of angiostrongyliasis in Australia, given the recent severe cases reported from the Sydney region.

Pepsin is a positive regulator of Ac-cathB-2 involved in the rat gut penetration of Angiostrongylus cantonensis

Background

Angiostrongyliasis caused by the rat lungworm, Angiostrongylus cantonensis (A. cantonensis), has globally spread from the traditional epidemic areas. The small intestine is the site where the third-stage larvae (L3) of this worm entered the host body, and parasite proteases are involved in this process. Ac-cathB-2, a cathepsin B-like cysteine of A. cantonensis, was formerly isolated from the insoluble part of fragmentised Escherichia coli without activity. The unplanned low activity of prokaryotic expression proteins and difficulties in genetic modification hindered understanding the function of this protein.

Methods

The recombinant Ac-cathB-2 was expressed and harvested from 293 T cells and the enzymatic property and the effects of processing on the activity of the recombinant protease were investigated in vitro. The expression of Ac-cathB-2 in response to external stimulation was assessed, and the function of this protease during host gut penetration was observed by using antiserum for inhibition.

Results

Of the life-cycle stages studied, L3 expressed the highest level of Ac-cathB-2 gene and released the corresponding gene product from the body. The expression of this gene was rapidly upregulated after incubating L3 in small intestine homogenate of rat. Recombinant Ac-cathB-2 was harvested from 293 T cell culture medium. This protease was activated by pepsin-HCl and the enabled Ac-cathB-2 could subsequently digest laminin and fibronectin readily. Moreover, the small intestine isolated from rat was disrupted after incubating with the activated Ac-cathB-2, resulting in the detachment of epithelial cells. Antiserum treatment inhibited the hydrolytic ability of recombinant Ac-cathB-2 by 82.7 %, and also reduced the tissue penetration of activated L3 by 41.2 %. Additionally, pre-incubation of L3 with artificial gastric acid increased the number of penetrating larvae by 53.2 %, and this alteration could be partly blocked by antiserum treatment.

Conclusion

We believe that Ac-cathB-2 from A. cantonensis might help the worm to penetrate the rat gut, because the protease was able to degrade the tissue components of host. Nevertheless, our results further indicated that host pepsin played a beneficial role in this process by cleaving Ac-cathB-2 for activation. Thus, Ac-cathB-2 may probably represent an important target for the control of A. cantonensis infection.

Update on Baylisascariasis, a Highly Pathogenic Zoonotic Infection

Baylisascaris procyonis, the raccoon roundworm, infects a wide range of vertebrate animals, including humans, in which it causes a particularly severe type of larva migrans. It is an important cause of severe neurologic disease (neural larva migrans [NLM]) but also causes ocular disease (OLM; diffuse unilateral subacute neuroretinitis [DUSN]), visceral larva migrans (VLM), and covert/asymptomatic infections. B. procyonis is common and widespread in raccoons, and there is increasing recognition of human disease, making a clinical consideration of baylisascariasis important. This review provides an update for this disease, especially its clinical relevance and diagnosis, and summarizes the clinical cases of human NLM and VLM known to date. Most diagnosed patients have been young children less than 2 years of age, although the number of older patients diagnosed in recent years has been increasing. The recent development of recombinant antigen-based serodiagnostic assays has aided greatly in the early diagnosis of this infection. Patients recovering with fewer severe sequelae have been reported in recent years, reinforcing the current recommendation that early treatment with albendazole and corticosteroids should be initiated at the earliest suspicion of baylisascariasis. Considering the seriousness of this zoonotic infection, greater public and medical awareness is critical for the prevention and early treatment of human cases.

Effects of albendazole combined with TSII-A (a Chinese herb compound) on optic neuritis caused by Angiostrongylus cantonensis in BALB/c mice

Background

Angiostrongylus cantonensis (A. cantonensis) infection can lead to optic neuritis, retinal inflammation, damage to ganglion cells, demyelination of optic nerve and visual impairment. Combined therapy of albendazole and dexamethasone is a common treatment for the disease in the clinic, but it plays no role in vision recovery. Therefore, it has been necessary to explore alternative therapies to treat this disease. Previous studies reported the neuro-productive effects of two constituents of Danshen (a Chinese herb)-tanshinone II-A (TSII-A) and cryptotanshinone (CPT), and this study aims to evaluate the impacts of TSII-A or CPT combined with albendazole on optic neuritis caused by A. cantonensis infection in a murine model.

Methods

To assess the effects of TSII-A or CPT combined with albendazole on optic neuritis due to the infection, mice were divided into six groups, including the normal control group, infection group and four treatment groups (albendazole group, albendazole combined with dexamethasone group, albendazole combined with CPT group and albendazole combined with TSII-A group). The infection group and treatment groups were infected with A. cantonensisand the treatment groups received interventions from 14 dpi (days post infection), respectively. At 21 dpi, the visual acuity of mice in each group was examined by visual evoked potential (VEP). The pathologic alteration of the retina and optic nerve were observed by hematoxylin and eosin (H&E) staining and transmission electronic microscopy (TEM).

Results

Infection of A. cantonensis caused prolonged VEP latency, obvious inflammatory cell infiltration in the retina, damaged retinal ganglions and retinal swelling, followed by optic nerve fibre demyelination and a decreasing number of axons at 21 dpi. In treatment groups, albendazole could not alleviate the above symptoms; albendazole combined with dexamethasone lessened the inflammation of the retina, but was futile for the other changes; however, albendazole combined with CPT and albendazole combined with TSII-A showed obvious effects on the recovery of prolonged VEP latency, destruction and reduction of ganglion cells, optic nerve demyelination and axon loss. Compared with albendazole-CPT compound, albendazole combined with TSII-A was more effective.

Conclusions

The current study demonstrates that albendazole combined with TSII-A plays a more effective role in treating optic neuritis caused by A. cantonensis in mice than with dexamethasone, as applied in conventional treatment, indicating that albendazole combined with TSII-A might be an alternate therapy for this parasitic disease in the clinic.

Eosinophilic meningitis caused by Angiostrongylus cantonensis: an emergent disease in Brazil

Eosinophilic meningitis (EoM) is an acute disease that affects the central nervous system. It is primarily caused by infection with the nematode Angiostrongylus cantonensis. This infection was previously restricted to certain Asian countries and the Pacific Islands, but it was first reported in Brazil in 2007. Since then, intermediate and definitive hosts infected with A. cantonensis have been identified within the urban areas of many states in Brazil, including those in the northern, northeastern, southeastern and southern regions. The goals of this review are to draw the attention of the medical community and health centres to the emergence of EoM in Brazil, to compile information about several aspects of the human infection and mode of transmission and to provide a short protocol of procedures for the diagnosis of this disease.

Microglia activation: one of the checkpoints in the CNS inflammation caused by Angiostrongylus cantonensis infection in rodent model

Angiostrongylus cantonensis (A. cantonensis) is a rodent nematode. Adult worms of A. cantonensis live in the pulmonary arteries of rats; humans are non-permissive hosts like the mice. The larva cannot develop into an adult worm and only causes serious eosinophilic meningitis or meningo-encephalitis if humans or mice eat food containing larva of A. cantonensis in the third stage. The differing consequences largely depend on differing immune responses of hosts to parasite during A. cantonensis invasion and development. To further understand the reasons why mice and rats attain different outcomes in A. cantonensis infection, we used the HE staining to observe the pathological changes of infected mice and rats. In addition, we measured mRNA levels of some cytokines (IL-5, IL-6, IL-13, Eotaxin, IL-4, IL-10, TGF-β, IFN-γ, IL-17A, TNF-α, IL-1β, and iNOS) in brain tissues of mice and rats by real-time PCR. The result showed that brain inflammation in mice was more serious than in rats. Meanwhile, mRNA expression levels of IL-6, IL-1β, TNF-α, and iNOS increased after mice were infected. In contrast, mRNA levels of these cytokines in rats brain tissues decreased at post- infection 21 days. These cytokines mostly were secreted by activated microglia in central nervous system. Microglia of mice and rats were showed by Iba-1 (microglia marker) staining. In micee brains, microglia got together and had more significant activation than in rats brains. The results demonstrate that mice and rats have different CNS inflammation after infection by A. cantonensis, and it is in line with other researchers' reported findings. In conclusion, it is suggested that microglia activation is probably to be one of the most important factors in angiostrongyliasis from our study.

Eosinophilia à deux: a brain nagging souvenir from the Philippines

Angiostrongylus cantonensis is the most common cause of eosinophilic meningitis. Although a rare condition among travelers, increased travel and global transportation of food products may result in more cases across non-endemic, developed countries in the future. We here describe two men with headache and painful skin after visiting the Philippines as presenting symptoms. Subsequently, confusion and focal neurologic symptoms developed. Both had increased serum eosinophils; however, CSF eosinophilia was only demonstrated after repeated lumbar puncture. In the CSF of both, Angiostrongylus spp. DNA was detected. Both were treated with albendazole combined with corticosteroids, after which symptoms improved.

Animal model of human disease with optic neuritis: neuropapillitis in a rat model infected with Angiostrongylus cantonensis

Human Angiostrongylus cantonensis (A. cantonensis) is a food-borne parasitic disease and can cause optic neuritis. Increasing clinical angiostrongyliasis cases with optic neuritis have been reported, but the pathogenesis has not been fully understood until now. Here, we applied rats with A. cantonensis infection as an animal model to study the pathogenesis of optic neuritis caused by the infection. We observed that the optic disk of experimental rats appeared hyperemic, the retina vein became thick, and the visual evoked potential (VEP) latency was prolonged. There were obvious inflammatory cell infiltration in the retina and optic nerve adventitia followed with obvious optic nerve fiber demyelination and retina ganglion swelling. We also evaluated the effect of dexamethasone combined with albendazole on optic neuritis of rats infected with A. cantonensis. The results showed it had no obvious effect to prevent progressive visual deterioration for optic neuritis caused by A. cantonensis. The studies provided evidence that the pathogenesis of optic neuritis in infected rats was correlated to optic nerve demyelination and ganglion cell damage caused by optic nerve inflammation, and the common therapy to this disease was not so effective. Based on the above results, it may be necessary to combine neuroprotective agents with common therapy to treat and protect optic nerve and ganglion cells from their secondary injury.

The pathogenesis of optic neuritis caused by Angiostrongylus cantonensis in BALB/c mice

BACKGROUND

One of the most common causes of meningitis in South East Asia is angiostrongyliasis or infection by the parasitic nematode Angiostrongyliasis cantonensis. Although this nematode usually resides in the pulmonary arteries of rats, its incidental occurence in other hosts such as humans can cause optic neuritis and lead to serious vision sequelae. Nevertheless, there are currently no systematic studies conducted in this area.

METHODS

In order to study the pathogenesis of optic neuritis, mice were tried as a new animal model to study and challenge with A. cantonensis on 7d, 14d and 21d, respectively. Electroretinogram (ERG), visual evoked potential (VEP), ophthalmoscopy and histology were examined on day 7d, 14d and 21d and tribendimidine (TBD) was later used to treat optic neuritis on day 14d for a week to evaluate its therapeutic effects.

RESULTS

Infection of A. cantonensis caused obvious inflammatory cell infiltration in the retina and optic nerve adventitia in day 14d and 21d followed by optic nerve fiber demyelination and retinal ganglion swelling at day 21d in the challenged mice. Prolonged VEP latency and decreased ERG amplitude were also observed on day 21. After treatment of TBD in the infected mice, retinal and optic nerve inflammation were alleviated, but VEP latency and ERG amplitude did not improve on day 21d and 28d.

CONCLUSIONS

The current study provides evidence that A. cantonensis can cause optic neuritis along with optic nerve demyelination and retinal ganglion cell damage in a mouse model. TBD alone treatment can improve the symptoms of optic neuritis, but does not aid in vision recovery, suggesting that both neuroprotective agents and Dexamethasone should be administered, along with treatment for the infection, to protect the optic nerve and ganglion cells. Furthermore, as the symptoms of optic neuritis caused by A. cantonensis in mice are similar to the optic neuritis in multiple sclerosis (MS) human patients, we suggest that the BALB/c mouse model provided in this study may be useful to explore therapies of optic neuritis in MS patients.

Angiostrongylus cantonensis eosinophilic meningitis: a clinical study of 42 consecutive cases in French Polynesia

INTRODUCTION

In endemic areas, eosinophilic meningitis is mainly caused by Angiostrongylus cantonensis. We describe a series of this poorly-known condition.

METHODS

Retrospective cohort study (2000-2012) including all patients diagnosed with eosinophilic meningitis in French Polynesia.

RESULTS

Forty-two patients (males: 61.9%, age: 22 (IQR 17-32)) were diagnosed with a serologically proven (n=13) or probable A. cantonensis meningitis, mostly during the dry season (66.6%) and following the consumption of or prolonged contact with an intermediate/paratenic host (64.3%). No differential diagnosis was found in probable cases, in whom serological tests were performed earlier (7.5 days (6.5-10)) compared to positive patients (7.5 (6.5-10) versus 11 (7-30) days, p=0.02). The most commonly reported symptom was headache (92.8%). Fever (7.1%) and biological inflammatory syndrome (14.3%) were rare. Blood eosinophil count was 1200/mm(3) (900-2548). Cerebrospinal fluid (CSF) analysis disclosed a protein level of 0.9 g/L (0.7-1.1), a CSF/plasma glucose ratio of 0.50 (0.40-0.55), and 500 leucocytes/mm(3) (292-725; eosinophils: 42.0% (29.5-60); lymphocytes: 46.5% (32.5-59.0)). Thirteen cases (31.0%) were severe, with 11 focal neurological deficits. A delayed hospital referral (OR 1.13, p=0.05) was associated with severity.

CONCLUSIONS

A. cantonensis meningitis must be evocated in young patients with meningitic syndrome, severe headache, and CSF inflammation with predominance of eosinophils.

Clinical manifestations of Eosinophilic meningitis due to infection with Angiostrongylus cantonensis in children

Eosinophilic meningitis, caused by the nematode Angiostrongylus cantonensis, is prevalent in northeastern Thailand, most commonly in adults. Data regarding clinical manifestations of this condition in children is limited and may be different those in adults. A chart review was done on 19 eosinophilic meningitis patients aged less than 15 years in Srinagarind Hospital, Faculty of Medicine, Khon Kaen University, Thailand. Clinical manifestations and outcomes were reported using descriptive statistics. All patients had presented with severe headache. Most patients were males, had fever, nausea or vomiting, stiffness of the neck, and a history of snail ingestion. Six patients had papilledema or cranial nerve palsies. It was shown that the clinical manifestations of eosinophilic meningitis due to A. cantonensis in children are different from those in adult patients. Fever, nausea, vomiting, hepatomegaly, neck stiffness, and cranial nerve palsies were all more common in children than in adults.

Eosinophilic meningitis

Eosinophilic meningitis is defined by the presence of at least 10% eosinophils in the total cerebrospinal fluid (CSF) leukocyte count. Although there are several possible causes of eosinophils in the CSF, parasitic infection is the main cause. The three common parasites causing eosinophilic meningitis include Angiostrongylus cantonensis, Gnathostoma spinigerum, and Taenia solium. Even though these parasites are endemic in tropical countries, they are now spreading globally due to extensive traveling, and physicians worldwide should pay more attention to this condition. This chapter will review risk factors, clinical manifestations, and treatment of these three parasites.

Treatment of angiostrongyliasis using a combination of albendazole and dexamethasone: the results of a retrospective and comparative study

As the information available on the treatment of angiostrongyliasis with a combination of albendazole and dexamethasone is limited, the efficacy of such therapy was assessed using data collected during the 2006 outbreak of angiostrongyliasis in Beijing. In a retrospective and controlled study, 35 patients treated with albendazole-dexamethasone (given 20 mg albendazole/kg and 3 mg dexamethasone daily for 7 days) were compared with 34 controls who were treated only symptomatically (with acetaminophen or other drugs). Compared with the controls, the patients given the combination were less likely to have headaches after 7 days (P = 0·038), tended to have headaches that cleared quicker (P = 0·010), and received fewer doses of acetaminophen (P = 0·036). Since no serious adverse effects were observed, a 1-week treatment with a combination of albendazole and dexamethasone appears both safe and beneficial in the treatment of angiostrongyliasis.

Efficacy of albendazole combined with a marine fungal extract (m2-9) against Angiostrongylus cantonensis-induced meningitis in mice

The pathogenesis of angiostrongyliasis, resulting from Angiostrongylus cantonensis invasion of the human central nervous system, remains elusive. Anthelmintics are usually used to kill worms, although dead worms in the brain may cause severe inflammation which will lead to central nervous system damage. Therefore, combination therapy with anthelmintics and anti-inflammatory drugs in the treatment of human angiostrongyliasis needs further study. To evaluate the efficacy of albendazole combined with a marine fungal extract (m2-9) in A. cantonensis infection, BALB/c mice infected by the third-stage larvae of A. cantonensis were divided into three groups: mice treated with albendazole or m2-9 alone or in combination from day 5 post-inoculation (PI). Several efficacy parameters were recorded, including weight change, worm recovery, neurological function, behavioural analysis, eosinophil and leucocyte counts. The results showed that combination therapy increased body weight, reduced worm burden, improved learning ability, memory and action, decreased neurological dysfunction and leucocyte response in these mice. The combination of albendazole and m2-9 treatment significantly decreased leucocyte response and increased the frequency of rearing, compared to infected mice treated with either drug alone. Therefore, m2-9 is a natural product with potentially significant therapeutic value for angiostrongyliasis and is worthy of further study.

How can clinicians ensure the diagnosis of meningitic angiostrongyliasis?

Meningitic angiostrongyliasis (MA), caused by Angiostrongylus cantonensis, is often diagnosed by clinical criteria alone, because the confirmative serologic tests are not always available in the rural endemic areas. In this study, we evaluated the relationship between various clinical parameters of MA and the sero-positivity to sort out the predictive parameters to ensure the diagnosis. We enrolled consecutive adults in whom MA had been clinically diagnosed, who had serologic results for A. cantonensis, and negative serologic results for Gnathostoma spinigerum. There were 75 eligible patients; 26 (34.7%) and 49 (65.3%) patients who had negative and positive serologic tests for A. cantonensis, respectively. Baseline characteristics and laboratory results were comparable between sero-positive and -negative groups. Only the cerebrospinal fluid (CSF) eosinophil counts of 40% or higher was significantly predictive for positive serologic test with the adjusted odds ratio of 4.970 (95% confidence interval of 1.337-18.477). In diagnostic facilities in the endemic areas with the limited availability of serologic tests, clinicians can ensure the diagnosis of MA by using CSF eosinophil level.

Zoonotic helminths affecting the human eye

Nowaday, zoonoses are an important cause of human parasitic diseases worldwide and a major threat to the socio-economic development, mainly in developing countries. Importantly, zoonotic helminths that affect human eyes (HIE) may cause blindness with severe socio-economic consequences to human communities. These infections include nematodes, cestodes and trematodes, which may be transmitted by vectors (dirofilariasis, onchocerciasis, thelaziasis), food consumption (sparganosis, trichinellosis) and those acquired indirectly from the environment (ascariasis, echinococcosis, fascioliasis). Adult and/or larval stages of HIE may localize into human ocular tissues externally (i.e., lachrymal glands, eyelids, conjunctival sacs) or into the ocular globe (i.e., intravitreous retina, anterior and or posterior chamber) causing symptoms due to the parasitic localization in the eyes or to the immune reaction they elicit in the host. Unfortunately, data on HIE are scant and mostly limited to case reports from different countries. The biology and epidemiology of the most frequently reported HIE are discussed as well as clinical description of the diseases, diagnostic considerations and video clips on their presentation and surgical treatment.

Clinical manifestations of eosinophilic meningitis caused by Angiostrongylus cantonensis: 18 years' experience in a medical center in southern Taiwan

BACKGROUND

With the improvement of public health, eosinophilic meningitis associated with Angiostrongylus cantonensis infection is now seldom reported in Taiwan. Eosinophilic meningitis typically occurred sporadically in children. This study aims to analyze the clinical manifestations and change in the contemporary epidemiology of eosinophilic meningitis in Taiwan.

METHODS

This is a retrospective study of patients diagnosed with eosinophilic meningitis at Kaohsiung Veterans General Hospital, from December 1991 to September 2009. The demographic characteristics, clinical presentations, laboratory data, radiographic imaging, and treatment and clinical outcome were analyzed. A PubMed search with the keywords of eosinophilic meningitis, A cantonensis, and Taiwan was performed to retrieve cases of eosinophilic meningitis caused by A cantonensis since 1960.

RESULTS

Thirty-seven patients were diagnosed to have eosinophilic meningitis during a period of 18 years. The median age was 32 years (range, 2-80 years). Ninety five percent (35/37) of the patients were adults. The median incubation period was 10.5 days (range, 3-80 days). Most of the patients presented with headache (29, 78%), fever (25, 68%), and 11(30%) had hyperesthesia. Patients with hyperesthesia had longer incubation period (55 vs. 7 days, p=0.004), lower serum immunoglobulin E levels (127.5 vs. 1295 IU/mL, p<0.001), and longer duration between symptom onset and spinal taps (14 vs. 5 days, p=0.011). Three patients presented initially with lymphocytic meningitis, and eosinophilia only appeared on a second lumbar puncture. Magnetic resonance imaging of the brain disclosed leptomeningeal enhancement (17/26, 65%) and increased signal intensity (10/26, 38%) on T2-weighted and fluid-attenuated inversion recovery images. There were eight relapses and two patients died. No sequela was noted except in one 2-year-old toddler, who had weakness of both lower limbs.

CONCLUSIONS

The epidemiology of eosinophilic meningitis has changed during the past two decades in Taiwan and occurs mainly in adults in the setting of outbreaks. Hyperesthesia; repeated lumbar puncture in cases with lymphocytic meningitis of uncertain cause; and a detailed history, including food consumption, are important to establish an accurate diagnosis.

Helminth infections of the central nervous system occurring in Southeast Asia and the Far East

Although helminth infections of the central nervous system (CNS) are rare, their public health implications must not be neglected. Indeed, several helminth species can cause cerebrospinal infections, especially if humans serve as intermediate or non-permissive host. The diagnosis of cerebrospinal helminthiases is difficult, and the detection of parasites in cerebrospinal fluid is rarely successful. Cerebrospinal helminth infections therefore often remain undetected, and hence prognosis is poor. Increases in tourism and population movements are risk factors for cerebrospinal helminthiases and infections pose particular challenges to clinicians in non-endemic areas. In this review, we focus primarily on food-borne helminthiases that are endemic and often emerging in Southeast Asia and the Far East, namely angiostrongyliasis, gnathostomiasis, sparganosis, paragonimiasis and cysticercosis. Additionally, we discuss neuroschistosomiasis, a disease that is transmitted through human-water contact. For each disease, we describe the pathogen, its transmission route and possible mechanisms for entering the CNS. We also summarise common signs and symptoms, challenges and opportunities for diagnosis, treatment, clinical management, geographical distribution and epidemiology. The adoption of a comprehensive set of diagnostic criteria for different cerebrospinal helminthiases is proposed, including epidemiological history, typical signs and symptoms, neuroimaging and laboratory findings. Finally, risk factors, and research needs for enhanced patient management and population-based control measures are discussed.

Anti-CCR3 monoclonal antibody inhibits eosinophil infiltration in Angiostrongylus cantonensis-infected ICR mice

ICR mice were each infected with 35 Angiostrongylus cantonensis larvae. One group of mice received an intraperitoneal injection of anti-CCR3 monoclonal antibody (mAb) (50 microg) at 10 days post-infection (dpi), while another similarly-treated group also received a booster injection (25 microg) at 12 dpi. All the mice were sacrificed at 14 dpi for pathological examination, enzyme-linked immunosorbent assay analysis and RNA extraction. The infiltration of eosinophils and the severity of eosinophilic meningitis were reduced in both the mAb-treated groups, relative to infected but untreated animals. The levels of CCL11 (eotaxin) in the peripheral circulation and the expression of the Th2-type cytokine interleukin-5 in the brains were significantly reduced. A. cantonensis infection is the major cause of eosinophilic meningoencephalitis in Taiwan, and the results of this study could be useful for the development of strategies to reduce the neurological damage caused by this infection.

Preliminary molecular characterization of the human pathogen Angiostrongylus cantonensis

Background

Human angiostrongyliasis is an emerging food-borne public health problem, with the number of cases increasing worldwide, especially in mainland China. Angiostrongylus cantonensis is the causative agent of this severe disease. However, little is known about the genetics and basic biology of A. cantonensis.

Results

A cDNA library of A. cantonensis fourth-stage larvae was constructed, and ~1,200 clones were sequenced. Bioinformatic analyses revealed 378 cDNA clusters, 54.2% of which matched known genes at a cutoff expectation value of 10^-20. Of these 378 unique cDNAs, 168 contained open reading frames encoding proteins containing an average of 238 amino acids. Characterization of the functions of these encoded proteins by Gene Ontology analysis showed enrichment in proteins with binding and catalytic activity. The observed pattern of enzymes involved in protein metabolism, lipid metabolism and glycolysis may reflect the central nervous system habitat of this pathogen. Four proteins were tested for their immunogenicity using enzyme-linked immunosorbent assays and histopathological examinations. The specificity of each of the four proteins was superior to that of crude somatic and excretory/secretory antigens of larvae, although their sensitivity was relatively low. We further showed that mice immunized with recombinant cystatin, a product of one of the four cDNA candidate genes, were partially protected from A. cantonensis infection.

Conclusion

The data presented here substantially expand the available genetic information about the human pathogen A. cantonensis, and should be a significant resource for angiostrongyliasis researchers. As such, this work serves as a starting point for molecular approaches for diagnosing and controlling human angiostrongyliasis.

Human angiostrongyliasis outbreak in Dali, China

Background

Several angiostrongyliasis outbreaks have been reported in recent years but the disease continues to be neglected in public health circles. We describe an outbreak in Dali, southwest China in order to highlight some key problems for the control of this helminth infection.

Methodology/Principal Findings

All available medical records of suspected angiostrongyliasis patients visiting hospitals in Dali in the period 1 October 2007–31 March 2008 were reviewed, and tentative diagnoses of varying strengths were reached according to given sets of criteria. Snails collected from local markets, restaurants and natural habitats were also screened for the presence of Angiostrongylus cantonensis. A total of 33 patients met criteria for infection, and 11 among them were classified as clinically confirmed. An additional eight patients were identified through a surveillance system put in operation in response to the outbreak. The epidemic lasted for 8 months with its peak in February 2008. Of the 33 patients, 97.0% complained of severe headache. 84.8% patients had high eosinophil cell counts either in the peripheral blood or in cerebrospinal fluid (CSF). Three-quarters of the patients were treated with a combination of albendazole and corticosteroids, resulting in significantly improved overall conditions. Twenty-two patients reported the consumption of raw or undercooked snails prior to the onset of the symptoms, and approximately 1.0% of the Pomacea canaliculata snails on sale were found to be infected with A. cantonensis. The snails were also found in certain habitats around Dali but no parasites were detected in these populations.

Conclusions/Significance

The import and sale of infected P. canaliculata is the likely trigger for this angiostrongyliasis outbreak. Awareness of angiostrongyliasis must be raised, and standardized diagnosis and treatment are needed in order to provide clinicians with a guide to address this disease. Health education campaigns could limit the risk, and a hospital-based surveillance system should be established in order to detect future outbreaks.

Angiostrongyliasis, caused by the rat lungworm Angiostrongylus cantonensis, is a potentially fatal food-borne disease. It is endemic in parts of Southeast Asia, the Pacific Islands, Australia, and the Caribbean. Outbreaks have become increasingly common in China due to the spread of efficient intermediate host snails, most notably Pomacea canaliculata. However, infections are difficult to detect since the disease has a rather long incubation period and few diagnostic clinical symptoms. Reliable diagnostic tests are not widely available. The described angiostrongyliasis epidemic in Dali, China lasted for eight months. Only 11 of a total of 33 suspected patients were clinically confirmed based on a set of diagnostic criteria. Our results demonstrate that the rapid and correct diagnosis of the index patient is crucial to adequately respond to an epidemic, and a set of standardized diagnostic procedures is needed to guide clinicians. Integrated control and management measures including health education, clinical guidelines and a hospital-based surveillance system, should be implemented in areas where snails are a popular food item.