The excretory/secretory products of fifth-stage larval Angiostrongylus cantonensis induces autophagy via the Sonic hedgehog pathway in mouse brain astrocytes

Angiostrongyliasis is induced by the nematode Angiostrongylus cantonensis and leads to eosinophilic meningitis and meningoencephalitis in humans. Excretory-secretory products (ESPs) are important investigation targets for studying the relationship between hosts and nematodes. These products assist worms in penetrating the blood-brain barrier and avoiding the host immune response. Autophagy is a catabolic process that is responsible for digesting cytoplasmic organelles, proteins, and lipids and removing them through lysosomes. This process is essential to cell survival and homeostasis during nutritional deficiency, cell injury and stress. In this study, we investigated autophagy induction upon treatment with the ESPs of the fifth-stage larvae (L5) of A. cantonensis and observed the relationship between autophagy and the Shh pathway. First, the results showed that A. cantonensis infection induced blood-brain barrier dysfunction and pathological changes in the brain. Moreover, A. cantonensis L5 ESPs stimulated autophagosome formation and the expression of autophagy molecules, such as LC3B, Beclin, and p62. The data showed that upon ESPs treatment, rapamycin elevated cell viability through the activation of the autophagy mechanism in astrocytes. Finally, we found that ESPs induced the activation of the Sonic hedgehog (Shh) signaling pathway and that the expression of autophagy molecules was increased through the Shh signaling pathway. Collectively, these results suggest that A. cantonensis L5 ESPs stimulate autophagy through the Shh signaling pathway and that autophagy has a protective effect in astrocytes.

In helminthes, Excretory-secretory products (ESPs) contains a wide range of molecules, including proteins, lipids, glycans, and nucleic acids, that assist in the penetration of host defensive barriers, reduction of oxidative stress, and avoid the host immune attack. It has been known as a key factor for parasite development, including feeding, invasion and molting. Therefore, ESPs is a valuable target for the investigation of the host-parasite relationships. However, only a few researches about the function of Angiostrongyliasis cantonensis ESPs have been verified to date. Angiostrongyliasis cantonensis, a blood-feeding nematode, and it is an important causative agent of eosinophilic meningitis and meningoencephalitis in human. Recent our studies have demonstrated that the A. cantonensis ESPs can induce oxidative stress, apoptosis, and immune response. In this study, we will use a mouse astrocytes as a model to investigate the signaling mechanisms of autophagy induction by ESPs treatment. First, the Microarray, Western blotting, and Transmission electron microscopy data demonstrated that A. cantonensis ESPs can induce autophagy generation in astrocytes. Next, ESPs-induced autophagy was activated via Sonic hedgehog (Shh) signaling, and it has a protective potential for astrocytes. These finding will provide new insights into the mechanisms and effects of the A. cantonensis ESPs.

The opposite roles of PAS-5 and Galectin-1 in immune response during the early infection of Angiostrongylus cantonensis

BACKGROUND

Angiostrongylus cantonensis is a human zoonotic nematode parasite. Our previous studies found that PAS-5 and Galectin-1 (Gal-1) proteins of A. cantonensis could be strongly recognized by sera from mice infected with A. cantonensis. In this study, we further evaluated the potential roles of these two proteins in the induction of immune response in mice.

METHODS

Mice were immunized with recombinant PAS-5 or Gal-1 and then challenged with 30 infective A. cantonensis larvae following the last immunization. We then examined the infected mice for changes in serum antibodies and cytokines by ELISA, CD4+ T cells and CD4+CD25+FoxP3+ regulatory T cells (Tregs) by flow cytometry, and tissue damage severity by hematoxylin-eosin (H&E) staining.

RESULTS

Compared with control mice, the PAS-5-immunized mice exhibited increased levels of serum antibodies and cytokines (except for IL-10) at different time points post-infection. PAS-5 immunization promoted significant proliferation of CD4+ T cells, and caused more damage in the brain tissue. Vaccination with Gal-1 inhibited the production of antibodies (except for IgG1) and IFN-γ, but promoted the expression of IL-4 and IL-10. Gal-1 immunization results in significant increases in the levels of CD4+CD25+FoxP3+ Tregs, and mild inflammatory changes.

CONCLUSIONS

Taken together, our findings show that PAS-5 enhances, but Gal-1 inhibits the immune response in the early stage of A. cantonensis infections.

Angiostrongylus cantonensis Eosinophilic Meningitis in an Infant, Tennessee, USA

Angiostrongylus cantonensis, the rat lungworm, is the most common infectious cause of eosinophilic meningoencephalitis worldwide. This parasite is endemic to Southeast Asia and the Pacific Islands, and its global distribution is increasing. We report A. cantonensis meningoencephalitis in a 12-month-old boy in Tennessee, USA, who had not traveled outside of southwestern Tennessee or northwestern Mississippi.

Characterization of the N-glycans of female Angiostrongylus cantonensis worms

Glycoconjugates play a crucial role in the host-parasite relationships of helminthic infections, including angiostrongyliasis. It has previously been shown that the antigenicity of proteins from female Angiostrongylus cantonensis worms may depend on their associated glycan moieties. Here, an N-glycan profile of A. cantonensis is reported. A total soluble extract (TE) was prepared from female A. cantonensis worms and was tested by western blot before and after glycan oxidation or N- and O-glycosidase treatment. The importance of N-glycans for the immunogenicity of A. cantonensis was demonstrated when deglycosylation of the TE with PNGase F completely abrogated IgG recognition. The TE was also fractionated using various lectin columns [Ulex europaeus (UEA), concanavalin A (Con A), Arachis hypogaea (PNA), Triticum vulgaris (WGA) and Lycopersicon esculentum (LEA)], and then each fraction was digested with PNGase F. Released N-glycans were analyzed with matrix-assisted laser desorption ionization (MALDI)-time-of-flight (TOF)-mass spectrometry (MS) and MALDI-TOF/TOF-MS/MS. Complex-type, high mannose, and truncated glycan structures were identified in all five fractions. Sequential MALDI-TOF-TOF analysis of the major MS peaks identified complex-type structures, with a α1-6 fucosylated core and truncated antennas. Glycoproteins in the TE were labeled with BodipyAF558-SE dye for a lectin microarray analysis. Fluorescent images were analyzed with ProScanArray imaging software followed by statistical analysis. A total of 29 lectins showed positive binding to the TE. Of these, Bandeiraea simplicifolia (BS-I), PNA, and Wisteria floribunda (WFA), which recognize galactose (Gal) and N-acetylgalactosamine (GalNAc), exhibited high affinity binding. Taken together, our findings demonstrate that female A. cantonensis worms have characteristic helminth N-glycans.

Development of Lateral Flow Immunoassay for Antigen Detection in Human Angiostrongylus cantonensis Infection

Angiostrongyliasis is difficult to be diagnosed for the reason that no ideal method can be used. Serologic tests require specific equipment and are not always available in poverty-stricken zone and are time-consuming. A lateral flow immunoassay (LFIA) may be useful for angiostrongyliasis control. We established a LFIA for the diagnosis of angiostrongyliasis based on 2 monoclonal antibodies (mAbs) against antigens of Angiostrongylus cantonensis adults. The sensitivity and specificity were 91.1% and 100% in LFIA, while those of commercial ELISA kit was 97.8% and 86.3%, respectively. Youden index was 0.91 in LFIA and 0.84 in commercial ELISA kit. LFIA showed detection limit of 1 ng/ml of A. cantonensis ES antigens. This LFIA was simple, rapid, highly sensitive and specific, which opened an alternative approach for the diagnosis of human angiostrongyliasis.

Effect of different helminth extracts on the development of asthma in mice: The influence of early-life exposure and the role of IL-10 response

It is not currently clear whether different parasites have distinct effects on the airway inflammatory response in asthma and whether exposure in early life to helminths have a stronger impact in a potential inhibitory effect on asthma. The aim of this study is to evaluate the effect of exposure to different helminth extracts on the development of allergic pulmonary response in mice, including early-life exposure. Different helminth extracts (Angiostrongylus costaricensis, Angiostrongylus cantonensis and Ascaris lumbricoides) were studied in female adult BALB/c and C57BL/6 IL-10-deficient mice in a protocol of murine asthma, injected intraperitoneally in different periods of exposure (early, pre-sensitization and post-sensitization). Cell counts in bronchoalveolar lavage (BAL), eosinophil peroxidase (EPO) from lung tissue, cytokine levels from BAL/spleen cell cultures, and lung histology were analyzed. Airway cellular influx induced by OVA was significantly inhibited by extracts of A. cantonensis and A. lumbricoides. Extracts of A. lumbricoides and A. costaricensis led to a significant reduction of IL-5 in BAL (p < 0.001). Only the exposure to A. lumbricoides led to an increased production of IL-10 in the lungs (p < 0.001). In IL-10-deficient mice exposed to A. costaricensis pre-sensitization, eosinophil counts and IL-5 levels in BAL and EPO in lung tissue were significantly reduced. In the early exposure to A. cantonensis, lung inflammation was clearly inhibited. In conclusion, different helminth extracts inhibit allergic lung inflammation in mice. IL-10 may not play a central role in some helminth-host interactions. Early exposure to helminth extracts could be a potential strategy to explore primary prevention in asthma.

Evaluation of dot immunogold filtration assay (DIGFA) for rapid serodiagnosis of eosinophilic meningitis due to Angio-strongylus cantonensis (Nematoda: Metastrongyloidea)

Angiostrongylus cantonensis is the most frequent cause of eosinophilic meningitis in humans in Thailand and worldwide. Because of difficulty of recovering the Angiostrongylus larvae from infected patients, detection of parasite-specific antibodies is used to support clinical diagnosis. This study tested serum samples from eosinophilic meningitis patients and individuals at risk of infection with A. cantonensis to evaluate a recently developed simple and rapid dot-immunogold filtration assay (DIGFA) for detection of specific antibodies against A. cantonensis. Purified 31-kDa glycoprotein of A. cantonensis and protein A colloidal gold conjugate were employed to detect the 31-kDa anti-A. cantonensis antibody in patients sera from the parasite endemic areas of northeast Thailand. The results were compared with those obtained by dot-blot enzyme-linked immunosorbent assay (ELISA) with 31-kDa A. cantonensis antigen. The overall positivity rate of DIGFA and dot-blot ELISA for A. cantonensis infection in 98 clinically diagnosed cases from three highly endemic districts in Khon Kaen province were 39.79% and 37.75%, respectively. Among 86 sera of subjects at risk of infection with A. cantonensis, 24.41% were positive by DIGFA and 23.25% by dot-blot ELISA. There were good correlation between the visual grading of DIGFA and dot-blot ELISA in both groups of defined sera. DIGFA is as sensitive and specific as dot-blot ELISA for confirming eosinophilic meningitis due to A. cantonensis infection, with advantages of simplicity, rapidity and without the use of specific and expensive equipment, and can be used in field settings.

IL-33 mediates the expressions of IL-5 and IL-13 in Angiostrongylus cantonensis-infected mice

Angiostrongylus cantonensis is the major cause of human eosinophilic meningoencephalitis. C57BL/6 mice were experimentally infected with 35 infectious larvae. Two groups of infected mice received intraperitoneal injections of mouse IL-33 (1μg) or anti-IL-33 monoclonal antibody (mAb) (10μg) 3days post infection (dpi) and subsequent booster shots of the same dose at 5day intervals. Blood samples from each group were collected weekly for assays. IgE levels were significantly increased in all infected mice. The eosinophil percentage and levels of IL-5 and IL-13 significantly increased in the IL-33-treated group relative to infected but non-treated animals. The level of IL-5 decreased in the mAb-treated group. The severity of eosinophilic meningitis was exacerbated in the IL-33 injected group. Taken together, these results suggest that IL-33 mediates the expressions of IL-5 and IL-13, and plays a crucial role in the pathogenesis of angiostrongylosis.

Angiostrongyliasis in Thailand: epidemiology and laboratory investigations

Cerebral angiostrongyliasis due to Angiostrongylus cantonensis continues to affect human health and productivity in Thailand. The dietary habits of the populace have been an important contributing factor, particularly in the northeast of the country where the disease is endemic and the indigenous people enjoy a local undercooked snail dish called "koi-hoi". Hundreds of cases of disease continue to be reported annually. Because of the difficulty in obtaining a definitive diagnosis, immunological methods have played an important role in the confirmation of A. cantonensis infection. Although enzyme-linked immunosorbent assay (ELISA) and immunoblot are test formats that have been used over the past decade, modern molecular approaches, such as PCR-based diagnostic techniques, are being developed and assessed as additional tests for the diagnosis of cerebral angiostrongyliasis. This short review focuses on the history, incidence, and laboratory diagnosis of angiostrongyliasis in Thailand.

Differential diagnosis of CNS angiostrongyliasis: a short review

The diagnostic criterion for eosinophilic meningitis (EOM) is the identification of an absolute count of 10 eosinophils per ml or more than 10% of the total white blood cells in the cerebrospinal fluid (CSF) in the proper clinical context. The most common cause of EOM is Angiostrongylus cantonensis infection, termed meningitic angiostrongyliasis (MA). Neurognathostomiasis (NG) is the main parasitic disease in the differential diagnosis of meningitic angiostrongyliasis. This short review is based on articles published on Medline between 2000 and 2012 related to EOM. There are three main approaches that can be used to differentiate between MA and NG, involving clinical factors, history of larval exposure, and serological tests. MA patients presented with acute severe headache but without neurological deficit, combined with a history of eating uncooked snails or slugs. NG patients always presented with motor weakness, migratory swelling, radicular pain and had history of eating uncooked poultry or fish. Specific antigenic bands in immunoblot tests are helpful tools to differentiate the two diseases. Other causes of eosinophilic meningitis are neurocysticercosis, cerebral paragonimiasis, Toxoplasma canis, Baylisascaris, tuberculous meningitis, and cryptococcal meningitis.

The current status of laboratory diagnosis of Angiostrongylus cantonensis infections in humans using serologic and molecular methods

Laboratory diagnosis of angiostrongyliasis relies on serological techniques, since definitive diagnosis is insensitive. Modern antibody detection methods focus on antibodies to the 29 and 31 kDa proteins of the parasite. Antigen detection may ultimately prove to be more reliable than antibody detection but no method has been adopted for clinical diagnostic use. Diagnosis using PCR amplification of DNA sequences specific to Angiostrongylus cantonensis have been developed but have not yet been validated for clinical use. Diagnostic tests have not been developed commercially and in the United States tests developed experimentally by non-commercial laboratories have to be approved by the Food and Drug Administration before they can be sold to other laboratories for diagnostic purposes.

Expression of recombinant antigenic proteins from Angiostrongylus cantonensis: a brief report

Cerebral angiostrongyliasis is an acute inflammation caused by the infection of the nematode Angiostrongylus cantonensis that results in eosinophilic meningitis. The current immunological assay of choice is an immunoblot that detects antibodies to a 31 kDa protein present in crude extracts of the female worm. Recently we have identified diagnostic targets from excretion and secretion products and determined the composition of the 31 kDa antigen after 2-D gel electrophoresis and mass spectrometry. Here we cloned and expressed five proteins in prokaryotic and eukaryotic systems. Recombinant proteins were purified and analysed by Western blot assays and among them 14-3-3, Lec5 and ES7 were recognized by Angiostrongylus-specific serum, although the signal was weak.

Matrix metalloproteinase-9 leads to claudin-5 degradation via the NF-κB pathway in BALB/c mice with eosinophilic meningoencephalitis caused by Angiostrongylus cantonensis

The epithelial barrier regulates the movement of ions, macromolecules, immune cells and pathogens. The objective of this study was to investigate the role of the matrix metalloproteinase (MMP)-9 in the degradation of tight junction protein during infection with rat nematode lungworm Angiostrongylus cantonensis. The results showed that phosphorylation of IκB and NF-κB was increased in mice with eosinophilic meningoencephalitis. Treatment with MG132 reduced the phosphorylation of NF-κB and the activity of MMP-9, indicating upregulation of MMP-9 through the NF-κB signaling pathway. Claudin-5 was reduced in the brain but elevated in the cerebrospinal fluid (CSF), implying that A. cantonensis infection caused tight junction breakdown and led to claudin-5 release into the CSF. Degradation of claudin-5 coincided with alteration of the blood-CSF barrier permeability and treatment with the MMP inhibitor GM6001 attenuated the degradation of claudin-5. These results suggested that degradation of claudin-5 was caused by MMP-9 in angiostrongyliasis meningoencephalitis. Claudin-5 could be used for the pathophysiologic evaluation of the blood-CSF barrier breakdown and tight junction disruption after infection with A. cantonensis.

[Analysis of larval excretory-secretory antigen and its immunodiagnosis of Angiostrongyliasis cantonensis infection]

OBJECTIVE

To analyze the diagnostic value of larval excretory-secretory antigen in Angiostrongylus cantonensis (LESA) infection.

METHODS

A.cantonensis larvae harvested from mice brain were cultured in vitro. The LESA and the adult worm antigens of A.cantonensis (AWA) were collected and analyzed using SDS-PAGE and Western blotting. Two ELISA systems were established using the two antigens (LESA-ELISA and AWA-ELISA) to detect the serum spectra from different sources.

RESULTS

SDS-PAGE and Western blotting displayed fewer protein and antigen bands for LESA than for the adult antigen. Two distinct bands of LESA (with relative molecular masses of 40 000 and 26 000) showed reactivity with the sera from patients with A. cantonensis infection. The serum levels of IgG and IgM antibodies to LESA increased at the beginning of infection in mice, reaching the peak on day 5 after infection and decreased on day 10. Compared with AWA-ELISA, LESA-ELISA showed a lower seropositive ratio in suspected patients with A.cantonensis, with also a lower cross-positive ratio in patients with schistosomiasis and clonorchis sinensis.

CONCLUSION

LESA possesses fewer antigen reaction bands than AWA. Although with a slightly lower positive ratio than AWA, LESA has a higher specificity for detecting serum antibodies in suspected cases of A.cantonensis infection, and therefore shows a potential for the diagnosis of angiostrongyliasis especially in the early stage and in current infection.

Monoclonal antibody 12D5 inhibits eosinophil infiltration in the brain of Angiostrongylus cantonensis-infected BALB/c mice

Each of BALB/c mice was infected with 50 Angiostrongylus cantonensis larvae. One group of mice received an intraperitoneal injection of 50 μg 12D5 monoclonal antibody (mAb) against a 98 kDa antigen of adult worms at 10 days post-infection (dpi), with a booster injection of 25 μg at 12 dpi. Five mice from each group were sacrificed at 14 dpi for pathological examination and RNA extraction. The infiltration of eosinophils and severity of eosinophilic meningitis were reduced in 12D5 mAb-treated mice compared with the infected mice without 12D5 treatment. The levels of eotaxin mRNA expression in spleen significantly increased and the expression of the Th2-type cytokine IL-5 significantly decreased. However, the expression of IL-4 was not changed. 12D5 mAb can observably enhance the survival rate of infected mice and reduce symptoms of angiostrongyliasis. A. cantonensis infection is a major cause of eosinophilic meningoencephalitis. The results of this study could be helpful for the development of treatment of human angiostrongylosis.

[Investigation on outbreak of angiostrongyliasis cantonensis due to consumption of snail food in Dali City]

OBJECTIVE

To investigate the potential cause of an outbreak of eosinophilic meningitis in Dali City in March, 2011.

METHODS

A retrospective investigation was performed among 18 consumers who had meal together. The clinical documents of inpatients were analyzed and the diagnoses were checked. The outpatients were investigated through a case survey. Pomacea snails on sale were examined for the infection status of Angiostrongylus cantonensis.

RESULTS

Of 18 persons, 16 consumed Pomacea snail food and 9 were infected with an infection rate of 56.3%. The two persons who did not consumed snail food were not infected. Serum samples of seven patients were examined for antibody to Angiostrongylus cantonensis in peripheral blood and 3 were proved positive (42.9%). The snails consumed by the patients came from the market, and the surveillance data showed that the infection rate of Angiostrongylus cantonensis of Pomacea snails was 7.3%.

CONCLUSION

According to the epidemiological survey, clinical manifestations, and laboratory examinations, the outbreak of eosinophilic meningitis is due to the consumption of Pomacea snails infected with Angiostrongylus cantonensis.

Seroprevalence of Angiostrongylus cantonensis in wild rodents from the Canary Islands

Background

Angiostrongylus cantonensis is a lungworm of rats (Muridae) that is the causative agent of human cerebral angiostrongyliasis. The life cycle of A. cantonensis involves rats and mollusks as the definitive and intermediate hosts, respectively. This study was designed to increase the knowledge about the occurrence and distribution of A. cantonensis in its definitive host in the Canary Islands, using parasitological and serological analysis in different areas and age groups.

Methodology/Principal Findings

Between 2009 and 2010, 54 black rats (Rattus rattus) from Tenerife were captured from six human-inhabited areas and sera samples were obtained. The lung nematodes were identified by morphological and molecular tools as A. cantonensis. The 31-kDa glycoprotein antigen was purified from A. cantonensis adult worms by electrophoresis and electroelution. Of the 54 tested rodents, 30 showed IgG antibodies against A. cantonensis 31-kDa antigen by ELISA. Therefore, the overall seroprevalence was 55.6% (95% CI: 42.4–68). Seroprevalent rodents were found in all the 6 areas. This 31-kDa antigen was not recognized by some sera of rats infected by other helminth species (but not A. cantonensis). Seroprevalence of IgG antibodies against A. cantonensis and prevalence based on the presence of adult worms showed significant correlation (R² = 0.954, p<0.05).

Conclusions/Significance

The present results could indicate a high prevalence of A. cantonensis in Tenerife and suggest the inclusion of two new zones in the distribution area of the parasite. The commonness and wide distribution of A. cantonensis in rats implies the presence of intermediate hosts, indicating that humans may be at risk of getting infected.

Application of recombinant SMR-domain containing protein of angiostrongylus cantonensis in immunoblot diagnosis of human angiostrongyliasis

The aim of this study was to find novel proteins expressed from an Angiostrongylus cantonensis adult female worm cDNA library for serodiagnosis of angiostrongyliasis. An immuno-dominant clone, fAC22, was identified by immunoscreening with pooled positive sera from proven angiostrongyliasis patients. The clone contained an open reading frame of 2,136 bp encoding a 80.5 kDa protein with a predicted isoelectric point of 5.8. The deduced amino acid sequence (712 amino acids) contained the conserved domain of Small mutS related (Smr) superfamily protein, with similarity with the Smr domain protein of Brugia malayi. The fusion His-tagged 81 kDa recombinant protein expressed as inclusion body in Escherichia coli was solubilized and purified by Ni-affinity chromatography for use in immunoblot analysis. Its sensitivity, specificity, positive and negative predictive values in immunodiagnostic test was 93.5, 91.5, 79.0 and 97.5%, respectively. Although some cross-reactivity of the antigen was observed among gnathostomiasis, bancroftian filariasis, ascariasis, echinococcosis, paragonimiasis and opisthorchiasis, sera from 14 other infections were all negative. These data indicate its possible application in immunodiagnosis of clinically suspected angiostrongyliasis. Key words: Angiostrongylus cantonensis,eosinophilic meningitis, recombinant fusion protein, immunodiagnosis

[Detection of circulating antigen of Angiostrongylus cantonensis by 12D5 and 21B7 monoclonal antibodies]

OBJECTIVE

To detect the rate of Angiostrongylus cantonensis infection and to study the effects of treatment so as to prepare monoclonal antibodies (McAbs), and gold immunochromatography assay (GICA) with 12D5 and 21B7 McAbs could be prepared in advance.

METHODS

Two McAbs (12D5 and 21B7) were applied to detect the circulating antigen (CAg) in the sera of rats infected with A. cantonensis and angiostrongyliasis patients respectively by double antibody sandwich ELISA. Either 12D5 or 21B7 McAbs was used as antibody and protein A was conjugated with colloid gold as the detection marker. A special pad for GICA was designed according to the reaction procedure, and CAg were detected by GICA in the sera of rats infected with A. cantonensis and angiostrongyliasis patients respectively.

RESULTS

12D5 McAb was identified as IgG1 and 21B7 McAb was IgM. Results from Western blotting showed that two McAbs could be used to identified 55 KD protein of adult worms of A. cantonensis. The detection rates of CAg in the sera of infected rats was 100% (48/48) and the detection rates of CAg in the sera of angiostrongyliasis patients was 100% (32/32). No cross-reaction to sera of patients with other infection of parasites, such as clonorchiasis, fasciolopsiasis, ancylostomiasis, ancylostomiasis, anisakiasis as well as schistosomiasis wee seen and normal sera did not react with 12D5 and 21B7 McAbs.

CONCLUSION

Results from sandwich ELISA and GICA with 12D5 and 21B7 McAbs showed high specificity and acting as detecting CAg of A. cantonensis in sera of infected animals and patients. We noticed that GICA with 12D5 and 21B7 was not only rapid and simple that without requirement of special instrument, but also rather sensitive and specific for the detection of current infection with A. cantonensis.

Comparison of prednisolone plus albendazole with prednisolone alone for treatment of patients with eosinophilic meningitis

Corticosteroid and the combination of corticosteroid and antihelminthic drug are safe and beneficial in relieving headaches in patients with eosinophilic meningitis. However, clinical trials comparing the efficacies of these regimens have never been reported. We conducted a prospective, open, randomized, controlled study to compare the efficacy of the combination of prednisolone plus albendazole and prednisolone alone for the treatment of eosinophilic meningitis. Our study had 53 patients in the combined treatment group and 51 patients in the prednisolone alone group. There were no significant differences between the two groups with regard to the number of patients who still had headaches after 14 days (0 versus 1, respectively; P = 0.49) and the median length of time until complete disappearance of headache (3 versus 3 days, respectively; P = 0.32. Prednisolone plus albendazole is no better than prednisolone alone for treatment of patients with eosinophilic meningitis.

Apoptosis in meningoencephalitis of Angiostrongylus cantonensis-infected mice

A hallmark of eosinophilic meningoencephalitis is infiltration of leukocytes into brain parenchyma and subarachnoid space infected by Angiostrongylus cantonensis. Apoptosis, a process that eliminates useless cells and counterbalances tissue homeostasis, is important for homeostasis of the immune system. In this study, we investigated the characteristics of cell death induced in BABL/c mice infected with A. cantonensis. We observed increased expression of the apoptotic proteins, caspase-3, caspase-8, caspase-9, and cytochrome c, and decreased expression of anti-apoptotic proteins, B-cell leukemia 2 and inhibitor of apoptosis protein 1. On immunohistochemistry, apoptotic proteins were localized within the leukocytes infiltrate. A terminal deoxynucleotidyl transferase-mediated deoxyuridine 5-triphosphate nick-end labeling assay to detect DNA fragmentation confirmed these observations. The infiltration of leukocytes present in the brain parenchyma and subarachnoid space in vivo may also express these apoptotic regulatory molecules, which demonstrates the capacity of these cells to undergo apoptosis.

Eosinophilic meningitis caused by Angiostrongylus cantonensis after ingestion of raw frogs

Angiostrongylus cantonensis is the most common cause of eosinophilic meningitis in humans after ingestion of raw or inadequately cooked intermediate hosts or food contaminated with infective third-stage larvae. Frogs are known to be a paratenic host of A. cantonensis, but have never been reported as the infectious source of human angiostrongyliasis in Taiwan. We report the first case of eosinophilic meningitis caused by A. cantonensis after ingestion of raw frogs (Rana plancyi).

Eosinophilic meningitis associated with angiostrongyliasis: clinical features, laboratory investigations and specific diagnostic IgG and IgG subclass antibodies in cerebrospinal fluid

Eosinophilic meningitis (EOM) associated angiostrongyliasis mostly induced by the nematode Angiostrongylus cantonensis, is a common disease with worldwide prevalence. Heavy infections can lead to chronic disabling disease and even death. This study was conducted to shed light on the overall specific IgG antibody response as well as the specific IgG antibody subclass responses in cerebrospinal fluid (CSF) of patients with EOM. Fifteen patients with EOM associated with angiostrongyliasis were included in the study. Sera were screened by immunoblotting for the presence of IgG antibody to the 29 kDaA. cantonensis antigenic polypeptide. CSF was examined by ELISA for the presence of specific IgG and IgG subclass antibodies. Patients presented with headache (100%), neck stiffness (20%), fever (40%), nausea (87%), vomiting (73%), paresthesia (7%), and muscle weakness (7%). Seven of 15 (47%) patients showed peripheral blood eosinophilia and all patients presented with eosinophils in CSF. A sensitivity of 80 % was obtained by combining the diagnostic values of immunoblotting in sera and IgG and IgG subclasses-based ELISA in CSF. The combination of a history of eating raw or semi-cooked infected foods, clinical features, complete blood count, differential cell counts, CSF profiles, and serum and CSF antibodies to A. cantonensis can be used to increase the sensitivity for the diagnosis of human angiostrongyliasis.

Multi-immunodot for rapid differential diagnosis of eosinophilic meningitis due to parasitic infections

A multi-dot enzyme-linked immunosorbent assay (ELISA) was developed for the rapid and simple differential diagnosis of eosinophilic meningitis due to helminth infections. Ultrafiltered, purified antigens of Parastrongylus (=Angiostrongylus) cantonensis, Gnathostoma spinigerum and Taenia solium metacestodes, the most common parasites that invade the central nervous system and cause eosinophilic pleocytosis, were dotted onto a single nitrocellulose membrane strip. Antigen-coated strips, when blocked with 5% skimmed milk and dried, were stable for at least 6 months at 4 degrees C. With peroxidase conjugated anti-human immunoglobulins and 4-chloro-1-naphthol as a substrate, antibodies in the corresponding patients' sera were clearly detected on the membrane strip as well-defined blue dots. Although cross-reactions between P. cantonensis and G. spinigerum antigens were observed with the use of partially purified antigens, the darkest dot correlated well with the infecting parasites in all cases. This fast, easy and economical multiple dot-blot ELISA method is useful for the differential diagnosis of eosinophilic meningitis caused by parasitic helminths, as semi-purified antigens can be easily obtained by ultrafiltration and used. Further improvements using highly specific parasite antigens may make this multi-immunodot test more suitable for wide-scale use in field studies and diagnostic laboratories.

[Headache after a stay in the Dominican Republic]

CASE HISTORY

In a 27-year-old female German patient severe headache and wandering paresthesias appeared one week after returning from a holiday in the Dominican Republic. After 3 weeks of ongoing symptoms she was admitted to our hospital with the suspicion of an inflammatory or infectious disease of the central nervous system. Upon admission slight stiffness of the neck, fever (38.2 C) and paresthesias of the right elbow and the right thigh were noticed.

LABORATORY FINDINGS

Cerebrospinal fluid (CSF) revealed an eosinophilic pleocytosis. In the acute phase of the disease, antibodies against nematodes were found in CSF, without corresponding antibody-reactivity in serum. In the course levels of nematode antibodies in CSF increased and antibody-reactivity in serum was observed. Thorough investigation for other infectious or inflammatory causes of eosinophilic meningitis revealed no abnormalities.

DIAGNOSIS, TREATMENT AND COURSE

Symptoms, onset within the typical incubation period and the eosinophilic meningitis lead to the diagnosis of a suspected Angiostrongyliasis. Successful treatment was achieved with a combination of oral albendazole and corticosteroids given for 4 weeks.

CONCLUSION

Infection with larvae of Angiostrongylus cantonensis is one of the main causes of eosinophilic meningitis worldwide. Human infection can occur after ingestion of intermediate hosts or contaminated vegetables. Angiostrongyliasis has been endemic to Southeast Asia and the Pacific Basin and only recently cases from the Caribbean have been described. Headache, paresthesias and the finding of an eosinophilic meningitis in patients returning from tropical or subtropical regions should lead to the suspicion and eventually the treatment of an Angiostrongyliasis.

Abdominal angiostrongyliasis: a case with severe evolution

A case of acute abdomen disease caused by abdominal angiostrongyliasis is reported. A 42-year-old otherwise healthy patient presented with a complaint of nine days of abdominal pain, constipation, disury, fever and right iliac fossa palpable mass. Exploratory laparotomy was performed. After surgical treatment the patient presented serious complications.

[Screening and identification of therapeutic effect evaluation antigens of angiostrongyliasis]

OBJECTIVE

To identify antigens which may help evaluate the therapeutic effect of angiostrongyliasis from adult worm antigen of Angiostrongylus cantonensis.

METHODS

The adult worm antigens of A. cantonensis were analyzed by Western blotting with the sera of rats infected with A. cantonensis before and after treatment. The sera of rats were tested by enzyme-linked immunosorbent assay (ELISA).

RESULTS

The antigens with relative molecular mass between 38,000 and 78,000 reacted not only with the sera of rats before treatment, but also with that after treatment. The antigens with M(r) between 190,000 and 17,000 reacted with the sera of rats before treatment but not with that after treatment; those with M(r) between 32,000 and 24,000 antigens strongly reacted with the former, but the reaction became much weakened with the latter. The AC32-IgG antibody appeared earlier than the AC-IgG, and disappeared rapidly after treatment. Six of the 10 treated rats became negative for AC-IgG as found by ELISA.

CONCLUSION

The antigens of adult worm antigen of A. cantonensis with M(r) of 190,000, 32,000, 24,000, 17,000 and 16,000 may serve as candidate antigens for therapeutic effect evaluation of angiostrongyliasis.

Necrotizing retinitis induced by Angiostrongylus cantonensis

PURPOSE

To describe a case of bilateral necrotizing retinitis induced by Angiostrongylus cantonensis.

DESIGN

Interventional case report.

METHODS

A 52-year-old Asian woman developed eosinophilic meningitis after eating several undercooked snails. One week later, sudden onset of vision loss was noted in both eyes. Widespread yellow retinal exudates were accompanied by bullous retinal detachment in both eyes.

RESULTS

Angiostrongylus cantonensis infection was confirmed by positive enzyme-linked immunosorbent assay of the serum and cerebrospinal fluid, and a positive Western blot test of the subretinal fluid. After treatment with mebendazole, levamisole, and corticosteroid, these necrotizing patches regressed gradually. However, the final visual acuity was no light perception.

CONCLUSIONS

Angiostrongylus cantonensis infection should be considered as one of the causes of necrotizing retinitis.

Elsberg syndrome with eosinophilic meningoencephalitis caused by Angiostrongylus cantonensis

A 42-year-old man was admitted to our hospital with a history of fever, headache and disorientation. His cerebrospinal fluid revealed eosinophilia and his serum had an antibody against Angiostrongylus cantonensis (A. cantonensis). Then, he was diagnosed as eosinophilic meningoencephalitis caused by A. cantonensis. He was treated with repeated lumbar punctures and oral prednisolone. Although a symptom he had been suffering from at the time of his admission was urinary retention, this symptom disappeared as his general condition improved. Therefore his case was considered to be Elsberg syndrome with eosinophilic meningoencephalitis caused by A. cantonensis.

[Detection of Angiostrongylus cantonensis circulating antigen by monoclonal antibodies]

OBJECTIVE

To prepare monoclonal antibodies (McAbs) against soluble antigens of adult worms of Angiostrongylus cantonensis (A. cantonensis) on the purpose to detect CAg of A. cantonensis.

METHODS

Female BALB/c mice were immunized with soluble antigens of adult worms of A. cantonensis and the spleen cells were fused with myeloma SP2/0 cells. The hybridoma cell strains were screened by enzyme-linked immunosorbent assay (ELISA) and Western blotting. Two McAbs (3F1 and 4H2) were applied to detect the CAg in the sera of rats and mice infected with A. cantonensis and angiostrongyliasis patients respectively by double antibody sandwich ELISA.

RESULTS

Three McAbs against A. cantonensis adult were obtained. Two McAbs (3F1, 4H2) were identified as IgG1 and one McAb (2A2) was identified as IgM. The titers of culture fluid and ascites was 1:25,600, 1:25,600, 1:12,800 and 1:80,000, 1:80,000, 1:40,000 respectively. Western blotting results showed three McAb could be used to identify 15,000 protein of adult worms of A. cantonensis. The detection rates of the CAg in the sera of infected rats and mice were 84.2% (48/57) and 87.2% (41/47) respectively. The detection rate of the CAg in the sera of angiostrongyliasis patients was 86.4% (19/22), and no cross reactions with sera from patients with schistosomiasis, cysticercosis cellulose, paragonimiasis and trichinellosis were observed. The CAg in the sera from mice examined at different periods after infection revealed positive 2 week after inoculation and the titer of CAg peaked 4 week after inoculation.

CONCLUSION

A new method of sandwich ELISA with high sensitivity and specificity to detect the serum A. cantonensis CAg has been obtained, it could be applicable to the diagnosis, observation of curative effect and epidemiology of angiostrongyliasis.

[Preparation and preliminary application of monoclonal antibodies against adult worm of Angiostrongylus cantonensis]

OBJECTIVE

To develop and identify monoclonal antibodies (McAbs) against adult worm of Angiostrongylus cantonensis and observe its applicability.

METHODS

BALB/c mice were immunized with soluble antigen of adult worms of A. cantonensis. The spleen cells of immunized mice were fused with myeloma cell, and the hybridoma secreting high titer of McAbs with high specificity was screened. By using the McAbs, serum of angiostrongyliasis patient and sera of the rats infected with A. cantonensis were detected by Western blotting and double antibody sandwich ELISA respectively.

RESULTS

Three McAbs were established (2A2, 3F1, 4H2), which all showed no cross reaction with antigens of Schistosoma japonicum, Paragonimus westermani, Cysticercus cellulosae and Trichinella spiralis. Western blotting analysis demonstrated that the three McAbs recognized a Mr 15,000 soluble antigen of adult worm of A. cantonensis and recognized the Mr 24,000 and Mr 15,000 circulating antigens from the serum of angiostrongyliasis patient. The double antibody sandwich ELISA detection showed a positive rate of 76.5%.

CONCLUSION

Three hybridoma cell lines against adult worm of A. cantonensis have been established which secret high titer of McAbs with high specificity and seem promising in detecting the circulating antigen of the angiostrongyliasis patient.

Longitudinal clinical and serological survey of abdominal angiostrongyliasis in Guaporé, southern Brazil, from 1995 to 1999

Abdominal angiostrongyliasis is a zoonotic infection caused by Angiostrongylus costaricensis, a nematode with an intra-vascular location in the mesentery. Our objective was to address several aspects of the natural history of this parasitosis, in a longitudinal clinical and seroepidemiological study. A total of 179 individuals living in a rural area with active transmission in southern Brazil were followed for five years (1995-1999) resulting in yearly prevalence of 28.2%, 4.2%, 10%, 20.2% and 2.8% and incidences of 0%, 5.9%, 8% and 1.5%, respectively. Both men and woman were affected with higher frequencies at age 30-49 years. In 32 individuals serum samples were collected at all time points and IgG antibody reactivity detected by ELISA was variable and usually persisting not longer than one year. Some individual antibody patterns were suggestive of re-infection. There was no association with occurrence of abdominal pain or of other enteroparasites and there was no individual with a confirmed (histopathologic) diagnosis. Mollusks were found with infective third-stage larvae in some houses with an overall prevalence of 16% and a low parasitic burden. In conclusion, abdominal angiostrongyliasis in southern Brazil may be a frequent infection with low morbidity and a gradually decreasing serological reactivity.

[Antigen analysis of Angiostrongylus cantonensis in different developmental stages]

OBJECTIVE

To analyze the difference among antigens of Angiostrongylus cantonensis in different developmental stages and identify dominant diagnostic antigen for angiostrongyliasis.

METHODS

Antigens of A. cantonensis in different developmental stages were analyzed by SDS-PAGE and immunoblot.

RESULTS

The protein bands of all developmental stages were similar on SDS-PAGE. The Mr 40000, 50000, 66000 and 80000 antigens reacted not only with the sera of rats infected by A. cantonensis but also with the sera of normal rats. The Mr 104000 antigen could be discerned by sera of rats infected with A. cantonensis for 2 weeks. The Mr 32000 antigen could be recognized by sera of rats 2 weeks after infection, and the reaction became stronger with the infection continued.

CONCLUSION

The Mr 40000, 50000, 66000 and 80000 antigens might result in the unspecific reaction in the immunodiagnosis of angiostrongyliasis using the crude antigen of A. cantonensis. The Mr 104000 of larva, Mr 33000 of adult females and Mr 32000 of the worms might be used as candidate antigens in early diagnosis and epidemiological survey of angiostrongyliasis.

Alteration of antibodies against the fifth-stage larvae and changes in brain magnetic resonance images in experimentally infected rabbits with Angiostrongylus cantonensis

Magnetic resonance (MR) imaging has been suggested to be helpful in delineating the lesions during the acute phase of angiostrongyliasis caused by Angiostrongylus cantonensis. In this study, antibody titers in serum samples of 3 rabbits were determined by enzyme-linked immunosorbent assay, and brain MR images were obtained from 6 rabbits. The antibody titer elevated rapidly in the first 4 wk postinfection (PI) before reaching a plateau. However, suspicious changes in brain MR images near the left lateral ventricle and hippocampus were found only in 1 rabbit on day 28 PI. These findings indicate that immunologic responses in the central nervous system at the early stage of angiostrongyliasis are not sufficient to be observed by image studies.

Common antigenicities between Angiostrongylus cantonensis and various species of snails

Studies on common antigenicities were carried out by using rabbit sera immunized with Angiostrongylus cantonensis adult worms or the third stage larvae and antigens of various species of snails and vice versa by the immunoblotting technique. The results obtained are summarized as follows: (1) Common antigenicities between A. cantonensis adult worms and snails susceptible to A. cantonensis were observed in a range of molecular weights of 14.3 to 200 kDa. In Puerto Rican pigmented Biomphalaria glabrata and Achatina fulca, which had high infection rates with A. cantonensis, we recognized 15 to 16 bands against the adult worm, especially the band with a molecular weight of 29 kDa, which had a more intense reaction. (2) Common antigenicities between A. cantonensis third stage larvae and snails susceptible to A. cantonensis, were observed in a range of molecular weights of 14.3 to 97.4 kDa, especially A. fulica and B. glabrata, where we detected many bands in molecular weight range of 18.4 to 43 kDa. Based on the common antigenicities between A. cantonensis and snails susceptible to A. cantonensis, it is possible that the common antigenicities are one of the factors defining the different susceptibilities of various species of snails to A. cantonensis, and more bands are seen with increasing infection rates with A. cantonensis. Of those bands, the protein with the molecular weight of 29 kDa may be the main common antigen between the A. cantonensis adult worm, the third stage larvae and the snails susceptible to A. cantonensis.

Infection of BALB/c mice with Angiostrongylus costaricensis decreases pulmonary inflammatory response to ovalbumin

SUMMARY The prevalence of asthma in developing countries is lower than in developed countries. Viral, bacterial and parasitic infections may be associated with this discrepancy. The relationship between parasitic infection and asthma prevalence is not clear. Previous controversial data have demonstrated that parasitic infection may either predispose or protect against the development of asthma. The aim of this study is to determine whether infection with Angiostrongylus costaricensis (A. costaricensis) decreases inflammatory lung response to ovalbumin (OVA) in mice. Seven BALB/c mice were infected with A. costaricensis by orogastric gavage (10 larvae/mouse) on day (D) 0. The mice were immunized against OVA by intraperitoneal injection on D 5 and D 12 and received an intranasal OVA challenge (40 micro L) on D 15 and D 17. On D 19 bronchoalveolar lavage (BAL) was performed. Six BALB/c mice (control group) were immunized with OVA using the same protocol, but were not infected with A. costaricensis. Interleukin (IL)-1beta and IL-6 levels were measured in the BAL fluid by using commercial ELISA assays. Total cell counts and differential cell counts were performed in the BAL fluid samples. The group infected with A. costaricensis had lower total cell count in the BAL fluid when compared with the control group (0.11 x 10(6)cells/mL and 0.3 x 10(6)cells/mL, respectively; P = 0.013). BAL fluid IL-1beta levels in the infected group were significantly lower than in the control group (P = 0.008). IL-6 levels in BAL fluid were not different between the groups studied. We conclude that Angiostrongylus costaricensis infection in mice decreases pulmonary inflammatory response to OVA.

Cross-reactions with Ascaris suum antigens of sera from mice infected with A. suum, Toxocara canis, and Angiostrongylus cantonensis

Ascaris suum larval excretory-secretory (AsES) antigen and larval (AsLA) as well as adult somatic antigen (AsAA) which were thought to be possibly helpful in the diagnosis of visceral larva migrans (VLM) due to A. suum infection were investigated in the present study. Serum taken from mice orally inoculated with approximately 250 embryonated eggs of A. suum or Toxocara canis, or 40 third-stage larvae of Angiostrongylus cantonensis were assessed by enzyme-linked immunosorbent assay (ELISA) using the AsES antigen, AsLA or AsAA at 1, 2, 3, 4, 6 and 8 weeks post infection (WPI). The titer of serum IgG from mice infected with A. suum increased from 1 WPI and a peak at 4 WPI was observed when it reached approximately three times the level of uninfected control mice. Thereafter, it decreased gradually but remained high as found from 6 to 8 WPI. No cross-reactions of heterologous serum IgG against AsES antigen was observed, whereas heterologous serum IgM exhibited significant cross-reactions to AsES antigen. Cross-reactivities to AsLA and AsAA by heterologous serum IgG as well as IgM antibodies were also observed in the trial. Altogether, the AsES antigen apparently seemed to be superior to the other two somatic antigens when used in the diagnosis of A. suum-induced VLM with serum IgG as tested by ELISA. Moreover, it was the first report to test the possibly antigenic cross-reactivity between A. suum and A. cantonensis.

The influence of zinc in mice on infection with Angiostrongylus cantonensis

BALB/cByJ mice were divided into zinc-deficient (ZD), high zinc-supplemented (ZH), adequately zinc-replete (ZA) and normal control groups by daily dietary control. The body weight in ZD and ZH mice became significantly less than that of normal control mice from 4 weeks (P < 0.002) until 7 weeks (P < 0.0001) after consecutive zinc control. The kinetics of change in body weight of ZD and ZH mice after infection with Angiostrongylus cantonensis were similar to that of uninfected groups mentioned above. The worms recovered at days 7, 14 and 21 after infection from ZD and ZH mice were significantly more in number than that in control mice (P < 0.01). However, the worms from day 21 after infection were shorter in size than those in control mice (P < 0.01). The production of interleukin (IL)-5 was significantly depressed in cultured spleen cells from uninfected and infected ZD and ZH mice, compared with that from respective control group (P < or = 0.02). Furthermore, significantly lower eosinophil counts were observed in the cerebral spinal fluid(CSF) of ZD and ZH mice 3 weeks after infection than in the CSF of control mice (P < 0.001). The levels of immunoglobulins IgG, IgM, IgA and IgE in the supernatant of cultivated spleen cells and serum from ZD and ZH mice were all lower than those of control mice. Thus, the level of zinc correlated with the defence against infection by A. cantonensis, due to the influence of zinc on the growth of mice and their production of IL-5, eosinophils and immunoglobulins.

Immuno-PCR for Detection of Antigen to Angiostrongylus cantonensis Circulating Fifth-Stage Worms

Background: Definitive diagnosis of infestation with Angiostrongylus cantonensis is difficult because the parasitic nematode is undetectable in the cerebrospinal fluid (CSF) of one-half of afflicted patients and the diagnostic sensitivity of ELISA for circulating worm antigens in patient sera is low. We studied immuno-PCR as a diagnostic tool.

Methods: We studied 30 controls and 60 afflicted patients (30 confirmed by parasitologic analysis of CSF). We used a monoclonal antibody to capture circulating A. cantonensis antigens in serum samples. A DNA label generated by PCR amplification with biotinylated primer was bound by use of streptavidin to a biotinylated third antibody. Circulating antigens sandwiched by monoclonal antibody were detected by PCR amplification of the DNA label.

Results: The detection limit of the ELISA was 100–1000 times higher than that of the immuno-PCR. The concentrations of circulating antigens in patients were markedly higher than those in controls (Wilcoxon rank-sum test, P &lt;0.001). At a cutoff of 0.1 ng/L, sensitivity and specificity for immunodiagnosis of patients with angiostrongyliasis by immuno-PCR were 98% (95% confidence interval, 91–99%) and 100% (93–100%), respectively. The test was positive in all parasitologically confirmed cases.

Conclusions: Immuno-PCR is a promising technique for diagnosis of A. cantonensis infestation.

Evaluation of human IgG subclass antibodies in the serodiagnosis of angiostrongyliasis

Immunoglobulin G subclass antibody (IgG1, IgG2, IgG3, and IgG4) responses to the rat lungworm, Angiostrongylus cantonensis, were analyzed using the immunoblotting technique in an attempt to further improve the sensitivity and specificity for the serodiagnosis of human angiostrongyliasis. Serum samples from patients with proven angiostrongyliasis and from clinically suspected cases of angiostrongyliasis with eosinophilic meningitis were tested. Sera from patients with other parasitic illnesses and from healthy volunteers were also analyzed. The results indicate that the immunoblotting used to detect IgG4 antibodies to the antigenic band of an approximate molecular mass of 29 kDa from young adult somatic extract of A. cantonensis is the most reliable test. It gives accuracy, sensitivity, specificity, and positive and negative predictive values of 89.2%, 75%, 95%, 85.7% and 90.4%, respectively. More importantly, the test can discriminate between human angiostrongyliasis, gnathostomiasis and cysticercosis, three diseases that produce eosinophilic meningitis.

[IgG subclasses intrathecal synthesis patterns in eosinophilic meningoencephalitis due to Angiostrongylus cantonensis]

INTRODUCTION

There is a growing interest to know the characteristics of meningoencephalitis due to Angiostrongylus cantonensis because of it is an emergent disease.

OBJECTIVE

To describe the intrathecal synthesis pattern of IgG subclasses in pediatric patients suffering from eosinophilic meningoencephalitis due to Angiostrongylus cantonensis.

PATIENTS AND METHODS

Ten pediatric patients with the disease were studied. During the firs diagnostic lumbar puncture an eosinophilic pleocitosis was found. Simultaneously a serum sample was taken. Eight days later, a second lumbar and venous puncture was performed. To every serum and cerebrospinal fluid sample IgA, IgM, IgG, albumin and the four subclasses of IgG were quantified by immunodiffusion and a differential cell count.

RESULTS

During the first diagnostic lumbar puncture, all the cases had blood cerebrospinal fluid barrier dysfunction with absence of immunoglobulins intrathecal synthesis with a mean of 450 106cells/L and 48% of eosinophils average. In the second lumbar punction there was a 40% patients with dysfunction of the blood cerebrospinal fluid barrier and with a synthesis pattern IgA+IgM+IgG in the 50% o patients and with IgA+IgG in four patients. The synthesis pattern of IgG subclasses was IgG1+IgG2 in six patients, IgG1+IgG2+IgG3 in one patient, IgG1+IgG2+IgG4 in one more patient and two patients without intrathecal synthesis.

CONCLUSION

The intrathecal synthesis pattern of IgG subclasses can contribute to eosinophilic meningoencephalitis diagnosis due to Angiostrongylus cantonensis.

Antemortem diagnosis of canine neural angiostrongylosis using ELISA

A 5-month-old female Kelpie developed paraparesis, hind limb ataxia and spinal hyperaesthesia 4 days after ovariohysterectomy. Neurological examination demonstrated upper motor neuron signs in the pelvic limbs with lower motor neuron signs in the tail. Cerebrospinal fluid analysis demonstrated an increased protein concentration and marked eosinophilic pleocytosis. The dog was known to have eaten rats, snails and slugs. A tentative diagnosis of neural angiostrongylosis was made and later confirmed using an ELISA based on soluble antigens obtained from larval 4 Angiostrongylus cantonensis. Antibody titres from the patient's serum and CSF were 800 and 6400, respectively. The dog was treated successfully with prednisolone. ELISA testing of serum may provide a non-invasive means for diagnosing neural angiostrongylosis in dogs.

Blinded multi-laboratory evaluation of an in-house dot-blot ELISA kit for diagnosis of human parastrongyliasis

An in-house membrane dot-blot enzyme-linked immunosorbent assay kit, for the detection of specific antibody to a 31 kDa protein of Parastrongylus cantonensis was evaluated in a blinded multi-laboratory study. The kit was provided to technologists, who were trained in its use, from nine regional laboratories of Thailand. With an identical set of 20 coded serum samples and reference positive and negative controls, the kit was found to have a diagnostic sensitivity of 100% and a diagnostic specificity of 100% in all the laboratories. There was no obvious variation in quality among five lots of the antigen-coated nitrocellulose strips evaluated. The shelf life of the kit was > or = 6 months when the test components were stored at 4 degrees C and 18 months at -20 degrees C. The enzyme-linked immunoassay dot technique is easy to perform and does not require sophisticated electrical equipment; the result is available within 3 hours. If appropriate technical training is included, the application of this dot-blot ELISA kit in clinical laboratories throughout Thailand should be possible.

Specific IgG antibody subclasses to Angiostrongylus cantonensis in patients with angiostrongyliasis

Total IgG, IgG1, IgG2, IgG3, IgG4, IgA and IgM specific antibodies against Angiostrongylus cantonensis somatic antigen were determined by enzyme-linked immunosorbent assay (ELISA) in sera from proven human angiostrongyliasis (PA) cases, clinically suspected angiostrongyliasis cases with eosinophilic meningitis (EM) and healthy control (HC). The specific IgA antibody in each of the patient groups was significantly higher than those of the HC group (p < 0.05). The mean ELISA value of the specific IgM in the PA group was not significantly different from that of the HC group (p > 0.05). However, the mean specific IgM ELISA value in the EM group was significantly higher than that of the HC group (p < 0.05). The levels of the specific IgG and IgG subclasses in both patient groups were significantly higher than in the healthy control (HC) group (p < 0.001). Major differences were evident in the distribution of the IgG subclass antibodies between the patient groups. The IgG1 antibody demonstrated the highest sensitivity and specificity while the IgM and IgA responses were generally poor in both patient groups. The levels of the specific IgG antibody subclasses possibly explain immune responses to the parasite.

An outbreak of eosinophilic meningitis caused by Angiostrongylus cantonensis in travelers returning from the Caribbean

BACKGROUND

Outbreaks of eosinophilic meningitis caused by the roundworm Angiostrongylus cantonensis are rarely reported, even in regions of endemic infection such as Southeast Asia and the Pacific Basin. We report an outbreak of A. cantonensis meningitis among travelers returning from the Caribbean.

METHODS

We conducted a retrospective cohort study among 23 young adults who had traveled to Jamaica. We used a clinical definition of eosinophilic meningitis that included headache that began within 35 days after the trip plus at least one of the following: neck pain, nuchal rigidity, altered cutaneous sensations, photophobia, or visual disturbances.

RESULTS

Twelve travelers met the case definition for eosinophilic meningitis. The symptoms began a median of 11 days (range, 6 to 31) after their return to the United States. Eosinophilia was eventually documented in all nine patients who were hospitalized, although on initial evaluation, it was present in the peripheral blood of only four of the nine (44 percent) and in the cerebrospinal fluid of five (56 percent). Repeated lumbar punctures and corticosteroid therapy led to improvement in symptoms in two of three patients with severe headache, and intracranial pressure decreased during corticosteroid therapy in all three. Consumption of one meal (P=0.001) and of a Caesar salad at that meal (P=0.007) were strongly associated with eosinophilic meningitis. Antibodies against an A. cantonensis--specific 31-kD antigen were detected in convalescent-phase serum samples from 11 patients.

CONCLUSIONS

Among travelers at risk, the presence of headache, elevated intracranial pressure, and pleocytosis, with or without eosinophilia, particularly in association with paresthesias or hyperesthesias, should alert clinicians to the possibility of A. cantonensis infection.

Immunoblot evaluation of the specificity of the 29-kDa antigen from young adult female worms Angiostrongylus cantonensis for immunodiagnosis of human angiostrongyliasis

The antigenic components of Angiostrongylus cantonensis young adult female worm somatic extract (FSE) were revealed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting. The sera tested were from patients with proven angiostrongyliasis, other parasitic diseases, and healthy adults. Both the sera and cerebrospinal fluid (CSF) were tested from patients with clinical angiostrongyliasis. The CSF from patients with other neurological diseases were also included. Using SDS-PAGE, we found that the FSE comprised more than 30 polypeptides. Immunoblot analysis revealed at least 12 or 13 antigenic bands in patients with proven or clinical angiostrongyliasis, respectively. The patterns of reactivity recognized by the serum and CSF antibodies against FSE were similar. These antigenic components had molecular masses ranging from less than 14.4 to more than 94 kDa. The prominent antigenic band of 29-kDa might serve as a reliable marker for the diagnosis of angiostrongyliasis. The sensitivity, specificity, positive and negative predictive values of immunoblot analysis in this antigenic band were 55.6%, 99.4%, 83.3% and 97.4%, respectively.

Eosinophils in the cerebrospinal fluid of mice infected with Angiostrongylus cantonensis are resistant to apoptosis

Interleukin-5 (IL-5) transgenic mice were used to assess the immunological features of CSF eosinophils from mice infected with Angiostrongylus cantonensis. CSF eosinophils were hypodense by day 14 post infection (p.i.). CSF eosinophils survived longer in vitro than peritoneal eosinophils collected from cadmium sulphate (CdSO(4)) -treated normal IL-5 transgenic mice. Apoptosis was measured by Annexin V binding and the presence of a distinct laddering pattern of DNA fragmentation on agarose electrophoresis. Regardless of the presence or absence of Actinomycin D, CSF eosinophils collected from IL-5 transgenic mice from days 15-36 p.i. exhibited less apoptosis than peritoneal eosinophils collected from uninfected IL-5 transgenic mice. CSF eosinophils collected from A. cantonensis infected C57BL/6 mice at days 15-34 p.i. showed elongation of survival time and less apoptosis during in vitro cultivation. Reduced apoptosis was noted only in CSF eosinophils, but not in peritoneal eosinophils recovered from the same infected IL-5 transgenic mice. CPP32/Caspase 3 activity of cultured peritoneal eosinophils from both infected and uninfected IL-5 transgenic mice was higher than that of cultured CSF eosinophils. Stimulation with A23187 readily induced apoptosis of peritoneal eosinophils, but not CSF eosinophils or peritoneal eosinophils cultured with mouse recombinant IL-5. The latter cells were morphologically identical to hypodense eosinophils. RT-PCR analysis indicated that bcl-2 and bcl-x(L) mRNA expression was higher in CSF eosinophils compared with peritoneal eosinophils and this expression in the latter cells was upregulated after culture with mouse recombinant IL-5. These results suggest that CSF eosinophils, shifting to hypodense status through an accumulation from peripheral blood, are resistant to apoptosis. These changes may explain the long-lasting, helminthotoxic and neurotoxic actions of CSF eosinophils in A. cantonensis infection.

Eosinophilic meningitis due to Angiostrongylus cantonensis in a returned traveler: case report and review of the literature

Angiostrongylus cantonensis, the rat lungworm, is the principal cause of eosinophilic meningitis worldwide, and the increase in world travel and shipborne dispersal of infected rat vectors has extended this parasite to regions outside of its traditional geographic boundaries. We report a case of eosinophilic meningitis due to A. cantonensis in a patient who recently returned from a trip in the Pacific.

Angiostrongyliasis: analysis of antigens of Angiostrongylus costaricensis adult worms versus IgG from infected patients with Angiostrongylus cantonensis

The possibility of cross-reactivity was previously investigated by indirect ELISA with sera from Angiostrongylus cantonensis infections, normal controls and A. costaricensis antigen. 5 microg/ml of crude antigen from both sexes of each species reacted with diluted serum samples (1:800) of each of 20 cases of angiostrongyliasis and normal controls, and further with anti-human IgG conjugate at 1:1,000. The mean absorbance values were evaluated as follows; normal controls showed a value of 0.033 using A. costaricensis antigen lower than (0.085) A. costaricensis antigen. Both mean values of angiostrongyliasis cases were rather close (0.491) using A. costaricensis antigen and the other antigen (0.518). The present study continued with a crude antigen of 13 A. costaricensis females and males. Serum samples were analyzed; 27 sera of angiostrongyliasis, 30 negative controls and 193 cases of other parasitic infections (91 cases of nematodiasis; 45 cases of cestodiasis; 47 cases of trematodiasis and 10 cases of HIV) and 7 cases of other brain infections. This antigen was evaluated for ELISA with a concentration of 5 microg/ml, serum dilution 1:400 and anti-human IgG conjugate at 1:2,000. The test gave sensitivity and specificity at cut-off value 0.261; 92.59% and 73% respectively. The antigen was cross-reactive with 30 cases from 9 out of 10 different kinds of nematodiasis (gnathostomiasis, strongyloidiasis, ascariasis, hookworm infections, trichinosis, toxocariasis, trichuriasis, onchocercosis and Wuchereria bancrofti infections. Five cases from 3 of 6 kinds of cestodiasis (neurocysticercosis, echinococcosis and Hymenolepis nana infections) and 18 cases of 4 out of 5 kinds of trematodiasis (Paragonimus heterotremus infections, opisthorchiasis, schistosomiasis and fascioliasis). One case of other brain infections was observed. The crude antigen of A. costaricensis showed a high percentage sensitivity with serum antibodies of angiostrongyliasis cases. Low specificity of the test was observed by reactions of those serum antibodies with various kinds of antigenic molecules. This study provides baseline data for further immunodiagnosis of human angiostrongyliasis.