The value of an enzyme-linked immunosorbent assay for the diagnosis of schistosomiasis mansoni myeloradiculopathy

Evaluation of isotype-based serology for diagnosis of Schistosoma mansoni infection in individuals living in endemic areas with low parasite burden

Intestinal schistosomiasis is a chronic and debilitating disease that affects public health systems worldwide. Control interventions to reduce morbidity primarily involve the diagnosis and treatment of infected individuals. However, the recommended Kato-Katz (KK) parasitological method shows low sensitivity in individuals with low parasite loads and is not useful for monitoring elimination of parasite transmission at later stages. In the current study, we evaluated the accuracy of serum reactivity levels of different immunoglobulin isotypes in an enzyme-linked immunosorbent assay (ELISA), utilizing Schistosoma mansoni crude extracts, with the aim to improve the diagnosis of infected individuals with low parasite loads. The serum reactivity of IgM and IgG subclass antibodies (IgG1, IgG3, and IgG4) against soluble adult worm and egg antigen preparations was evaluated in residents from a schistosomiasis-endemic area in northern Minas Gerais, Brazil. The parasitological status of the study population was determined through fecal examination with multiple parasitological tests to create a consolidated reference standard (CRS) plus a fecal DNA detection test (q-PCR). Twelve months after praziquantel treatment, a second serum sample was obtained from the population for reexamination. A two-graph receiver operating characteristic curve (TG-ROC) analysis was performed using the serum reactivity of non-infected endemic controls and egg-positive individuals, and the cut-off value was established based on the intersection point of the sensibility and specificity curves in TG-ROC analyses. The diagnostic accuracy of each serological test was evaluated in relation to the parasitological CRS and to the combination of CRS plus qPCR results. The data revealed that serum reactivity of IgM and IgG3 against S. mansoni antigens did not allow identification of infected individuals from the endemic area. In contrast, serum IgG1 and IgG4-reactivity against schistosome antigens could distinguish between infected and non-infected individuals, with AUC values ranging between 0.728-0.925. The reactivity of IgG4 anti-soluble egg antigen - SEA (sensitivity 79 %, specificity 69 %, kappa = 0.49) had the best diagnostic accuracy, showing positive reactivity in more than 75 % of the infected individuals who eliminated less than 12 eggs per gram of feces. Moreover, serum IgG4 reactivity against SEA and against soluble worm antigen preparation (SWAP) was significantly reduced in the serum of infected individuals after 12 months of confirmed parasitological cure and in the absence of re-infection. These results reinforce that the described IgG4 anti-SEA ELISA assay is a sensitive alternative for the diagnosis of active intestinal schistosomiasis in individuals from endemic areas, including in those with a very low parasite load.

Mansonic neuroschistosomiasis in the childhood: an undiagnosed pathology?

Schistosomiasis is an endemic parasitic disease in several tropical countries. In Brazil, the only prevalent species of parasite responsible for schistosomiasis is Schistosoma mansoni. Neuroschistosomiasis is the second most frequent form of infection and the primary ectopic manifestation, with predominant involvement of the lower thoracic spinal cord and lumbar and lumbosacral regions. The frequent contact of children with contaminated ponds and the immaturity of their immune systems make this age group especially susceptible to infection by this parasite. Therefore, neuroschistosomiasis mansoni should always be considered in cases of transverse myelitis in children from endemic regions. The treatment for this condition is quite simple and effective, resulting in total recovery of neurological deficits if the diagnosis is made early.

Medullary neuroschistosomiasis in adolescence: case report and literature review

INTRODUCTION

Medullary neuroschistosomiasis is a severe complication of gastrointestinal infection by Schistosoma. There are several endemic areas, wherein the only causative species present is Schistosoma mansoni, which is responsible for the clinical manifestations of all cases in those areas.

METHODS

We report the case of a 13-year-old female with lumbar pain and progressive lower limb weakness, with a delayed diagnosis of medullary involvement by the parasite. We also reviewed the literature on the disease.

CONCLUSIONS

Although it is related to the less severe forms of schistosomiasis, one should pay attention to the diagnosis of neuroschistosomiasis in cases of transverse myelitis in patients who traveled to endemic areas. The delay in diagnosis and, consequently, the introduction of treatment may result in irreversible neurological sequelae.

Neuroesquistossomose

A neuroesquistossomose é uma complicação ectópica da esquistossomose, sendo cada vez mais relatada na literatura médica. Tal fato ocorre porque a incidência dessa complicação neurológica oscila entre 0,4% a 3% dos pacientes com esquistossomose e no Brasil há cerca de 16 milhões de esquistossomóticos. A forma de apresentação clínica da neuroesquistossomose mansônica varia com o estágio de evolução da esquistossomose. Na forma intestinal e hepatointestinal, o comprometimento raquimedular é mais freqüente. Já a neuroesquistossomose encefálica ocorre mais freqüentemente nos pacientes com hipertensão portal e/ou pulmonar. O diagnóstico diferencial faz-se principalmente com as doenças inflamatórias e infecciosas crônicas do SNC, principalmente quando o quadro de mielomeningorradiculite está presente: neurocisticercose raquimedular, paraparesia espástica tropical, meningite eosinofílica etc. O exame de LCR apresenta como alteração aumento de células, em geral de 100 a 400 células por mm3 , proteína discretamente aumentada, diferencial linfomonocitário predominante com presença de eosinófilos e reações imunobiológicas positivas para Schistosoma mansoni. A eficácia do tratamento está diretamente relacionada ao diagnóstico precoce. Quanto mais cedo iniciar o tratamento específico, maior será a chance de recuperação. Este tratamento baseia-se na utilização de vermicida associado a corticoesteróides por um período de 7 a 15 dias.no entanto, não são possíveis. São sugeridos aprimoramentos metodológicos para estudos futuros sobre essa questão.

Immunological Profile in Individuals with Schistosomal Myeloradiculopathy

BACKGROUND

Schistosomal myeloradiculopathy (SMR) is the most serious ectopic presentation of Schistosoma mansoni infection. The pathogenesis occurs mainly via the host inflammatory response to the eggs of the parasite that are stuck in the central nervous system, and the diagnosis is generally made by the exclusion of other neurological diseases.

OBJECTIVE

We aimed to evaluate the immune status of SMR patients and to identify a marker for SMR diagnosis.

METHODS

We enrolled 15 patients with a presumptive diagnosis of SMR, and the control groups included 17 patients with myelopathy associated with human T cell lymphotropic virus type 1 (HTLV-1) and 11 with other neurological disorders. The determination of soluble egg antigen-specific IgE and the levels of cytokines from Th1, Th2, Th17 and T-regulatory cell profiles and the chemokines MIP-1a and RANTES were measured in the cerebrospinal fluid (CSF) and serum using an ELISA technique.

RESULTS

We observed that SMR leads to an increase in IgE levels in the CSF compared to serum, and the levels of IL-13 and MIP-1α were significantly higher in the CSF and serum of the SMR patients than in the patients with HTLV-1-associated myelopathy. The levels of MIP-1α and RANTES were higher in the CSF than in the serum of the SMR group. The ratio between levels of IL-13, MIP-1α and RANTES over IL-10 was positive in the CSF of the SMR patients.

CONCLUSIONS

These results indicate that S. mansoni-specific IgE in the CSF is a promising marker for the diagnosis of SMR and that the cytokines and chemokines associated with the Th2 profile may be important factors in the immunopathogenesis of SMR.

Diagnosis of neuroschistosomiasis by antibody specificity index and semi-quantitative real-time PCR from cerebrospinal fluid and serum

We describe the case of a 16-year-old German male expatriate from Ghana who presented with obstipation, dysuria, dysaesthesia of the gluteal region and the lower limbs, bilateral plantar hypaesthesia and paraesthesia without pareses. A serum–cerebrospinal fluid (CSF) Schistosoma spp. specific antibody specificity index of 3.1 was considered highly suggestive of intrathecal synthesis of anti-Schistosoma spp. specific antibodies, although standardization of this procedure has not previously been described. Diagnosis was confirmed by detection of Schistosoma DNA in CSF by semi-quantitative real-time PCR at 100-fold concentration compared with serum. Accordingly the two diagnostic procedures, which have not previously been applied for routine diagnosis, appear to be useful for the diagnosis of neuroschistosomiasis. Clinical symptoms resolved following anthelmintic and anti-inflammatory therapy.

The contribution made bySchistosomainfection to non-traumatic disorders of the spinal cord in Malawi

In Malawi, although schistosomal myelopathy has been reported in visitors from overseas who have swum in Lake Malawi, the incidence of this disorder in local residents has never been investigated. Consecutive patients with non-traumatic disorders of the spinal cord were therefore recruited in a hospital and a rehabilitation centre in Blantyre. Of the 33 patients investigated, 16 were presumed to be cases of schistosomal myelopathy as they had the markers of past or current schistosomiasis and apparently no other conditions that could explain their clinical features. There was microscopical and/or immunodiagnostic evidence indicating that eight of these presumptive cases had active schistosomiasis. All 16 presumptive cases had symptoms that were similar to those of 177 presumptive or proven cases of neuroschistosomiasis described in the scientific literature. Following antihelminthic treatment, eight of the presumptive cases showed marked improvement. Schistosomal myelopathy seems to occur relatively frequently in Malawi. Early treatment with praziquantel is strongly recommended for all patients with unexplained myelopathy and a history of exposure to schistosome cercariae.

Immunodiagnosis of CNS parasitic infections

The nature of many parasitic infections of the central nervous system (CNS) requires immunodiagnosis to confirm presumptive diagnoses. The CNS is the primary site of parasite infection for some parasitic organisms and for others, neurological infection occurs only in immunocompromised hosts. Still other parasites cause ectopic infections of the CNS and occur very rarely. This review concentrates on laboratory diagnosis of diseases that are caused by parasites with a primary predilection for the CNS. Emphasis is placed on laboratory diagnostic methods that are used and suitable for clinical diagnosis, rather than a comprehensive review of all the experimental methods that have been reported in the literature. Immunodiagnosis is not appropriate for the diagnosis of all parasitic infections of the CNS; in those cases, alternative diagnostic methods are presented, but not discussed in detail. In some instances potential new antigens or methods are presented, particularly if adoption of these methods is expected in the near future.

Schistosomiasis of the nervous system

Schistosomiasis is a parasitic disease caused by blood flukes of the genus Schistosoma. Currently 200 million people worldwide are infected. Neurological manifestations are a result of the inflammatory response of the host to egg deposition in the brain and spinal cord and is usually seen in patients with recent infection with no evidence of systemic illness. Cerebral and cerebellar disease can result in headache, seizure, and increased intracranial pressure. Cerebral schistosomiasis is more common in Schistosoma japonicum, but increasing cases due to Schistosoma mansoni are being reported in the literature. Other complications of cerebral schistosomiasis include delirium, loss of consciousness, visual field impairment, focal motor deficits, and ataxia. Myelopathy is the most common neurological manifestation of Schistosoma mansoni and the conus medullaris and cauda equine are the most common sites of involvement. Severe disease can result in flaccid paraplegia with areflexia, sphincter dysfunction, and sensory disturbance. Early recognition and prompt treatment are essential when physicians are faced with schistosomiasis involving the central nervous system. Schistosomicidal drugs, such as praziquantel, steroids and surgery, are the mainstay of therapy for this severe form of schistosomiasis.

New insights in diagnosing Schistosoma myelopathy

At present non-invasive tests for diagnosing Schistosoma myelopathy are sub-optimal. We present a novel serological method, using paired liquor and serum samples, resulting in the diagnosis of Schistosoma myelopathy in a male patient with proximal muscle weakness. The patient recovered after praziquantel treatment.

Update on eosinophilic meningoencephalitis and its clinical relevance

Eosinophilic meningoencephalitis is caused by a variety of helminthic infections. These worm-specific infections are named after the causative worm genera, the most common being angiostrongyliasis, gnathostomiasis, toxocariasis, cysticercosis, schistosomiasis, baylisascariasis, and paragonimiasis. Worm parasites enter an organism through ingestion of contaminated water or an intermediate host and can eventually affect the central nervous system (CNS). These infections are potentially serious events leading to sequelae or death, and diagnosis depends on currently limited molecular methods. Identification of parasites in fluids and tissues is rarely possible, while images and clinical examinations do not lead to a definitive diagnosis. Treatment usually requires the concomitant administration of corticoids and anthelminthic drugs, yet new compounds and their extensive and detailed clinical evaluation are much needed. Eosinophilia in fluids may be detected in other infectious and noninfectious conditions, such as neoplastic disease, drug use, and prosthesis reactions. Thus, distinctive identification of eosinophils in fluids is a necessary component in the etiologic diagnosis of CNS infections.

Immune response and pathogenesis of neuroschistosomiasis mansoni

The involvement of the central nervous system (CNS) by schistosomes may or may not determine clinical manifestations. When symptomatic, neuroschistosomiasis (NS) is one of the most severe presentations of schistosome infection. Considering the symptomatic form, Schistosoma mansoni causes almost always spinal cord disease. Cerebral and spinal cord disorders in S. mansoni infections are inflammatory conditions of the CNS that cause mild-moderate impairment of the blood-brain barrier and intrathecal synthesis of antibodies against schistosomal antigens. Little is known about the pathogenesis of NS, but available evidence strongly suggests that it depends basically on the presence of parasite eggs in the nervous tissue and on the host's immune response against the trapped eggs. Numerous eggs surrounded by granulomas lodged together in circumscribed areas of the CNS damage the nervous tissue by both the mass effect and the egg-induced inflammatory reaction. Vasculitis of immune etiology, which causes isquemic lesions, may also play an important role in the genesis of the neurological symptoms. Although the mechanisms involved in the immunophatogenesis of NS are largely unknown, initial investigations on cerebrospinal fluid (CSF) and serum cytokine profiles suggest the occurrence of inflammation as well as a skewed Th2 immune response that probably occur both locally and systemically.

Clinical characterization of neuroschistosomiasis due to Schistosoma mansoni and its treatment

The involvement of the central nervous system (CNS) by Schistosoma mansoni may or may not cause clinical manifestations. When symptomatic, neuroschistosomiasis mansoni (NSM) is one of the most severe presentations of this infection. The neurological manifestations are due to numerous granulomas grouped in confined areas of the spinal cord or the brain. Considering the symptomatic form, myelopathy is far more frequent than the cerebral disease. Spinal cord NSM presents as a low cord syndrome of acute/subacute progression usually associated with involvement of the cauda esquina roots. Lower limbs pain, weakness and sensory disturbance, and autonomic dysfunctions, particularly bladder dysfunction, are often present. Cerebrospinal fluid (CSF) examination generally shows an inflammatory pattern with or without eosinophils and/or IgG against schistosomal antigens. Magnetic resonance imaging (MRI) demonstrates signs of inflammatory myelopathy. Cerebral NSM presents as a slow-expanding intracranial tumor-like lesion. Its clinical manifestations are variable and depend on the increased intracranial pressure and on the site of the lesion. The diagnosis of spinal cord NSM is based on clinical evidence whereas the cerebral disease is usually diagnosed by biopsy of the nervous tissue. There is no consensus on the treatment of NSM. We discuss the literature data on this topic, and suggest a therapeutic approach based on our experience with 69 spinal cord NSM patients who have been followed up by a long period of time. Outcome is largely dependent on early treatment, particularly in the medullar disorder, and is better in cerebral NSM.

Neuroschistosomiasis

Schistosomiasis is an infection caused by digenetic trematode platyhelminths of the genus Schistosoma. These blood flukes use man and other mammals as definitive hosts and aquatic and amphibious snails as intermediate hosts. Of the schistosomal species, S. mansoni, S haematobium and S. japonicum are the most important to man and the most widely distributed. The infection affects about 200 million individuals in 74 countries of Latin America, Africa and Asia. Far less commonly, schistosomes reach the central nervous system (CNS). This may occur at any time from the moment the worms have matured and the eggs have been laid. For this reason, CNS involvement may be observed with any of the clinical forms of schistosomal infection. The presence of eggs in the CNS induces a cell-mediated periovular granulomatous reaction. When eggs reach the CNS during the early stages of the infection or during evolution of the disease to its chronic forms, large necrotic-exudative granulomas are found. In-situ egg deposition following the anomalous migration of adult worms appears to be the main, if not the only, mechanism by which Schistosoma may reach the CNS in these stages. The mass effect produced by the heavy concentration of eggs and the presence of large granulomas in circumscribed areas of the brain and spinal cord explains, respectively, 1) the signs and symptoms of increased intracranial pressure and focal neurological signs; and 2) the signs and symptoms of rapidly progressing transverse myelitis, usually affecting the lumbosacral segments of the spinal cord. Most of the cases of CNS involvement associated with the hepatosplenic and cardiopulmonary chronic forms, or with severe urinary schistosomiasis, though more frequent, are asymptomatic. In the patients with these clinical forms, the random and sparse distribution of eggs in the CNS indicates that the embolization of eggs from the portal mesenteric system to the brain and spinal cord constitutes the main route of CNS invasion by Schistosoma. The discrete inflammatory reaction elicited by the sparsely distributed eggs in the CNS explains the lack of neurological symptoms that could be produced by egg deposition.

Clinical-epidemiological profile of children with schistosomal myeloradiculopathy attended at the Instituto Materno-Infantil de Pernambuco

The most critical phase of exposure to schistosomal infection is the infancy, because of the more frequent contact with contaminated water and the immaturity of the immune system. One of the most severe presentations of this parasitosis is the involvement of the spinal cord, which prognosis is largely dependent on early diagnosis and treatment. Reports on this clinical form of schistosomiasis in children are rare in the literature. We present here the clinical-epidemiological profile of schistosomal myeloradiculopathy (SMR) from ten children who were admitted at the Instituto Materno-Infantil de Pernambuco over a five-year period. They were evaluated according to an investigation protocol. Most of these patients presented an acute neurological picture which included as the main clinical manifestations: sphincteral disorders, low back and lower limbs pain, paresthesia, lower limbs muscle weakness and absence of deep tendon reflex, and impairment of the gait. The diagnosis was presumptive in the majority of the cases. This study emphasizes the importance of considering the diagnosis of SMR in pediatric patients coming from endemic areas who present a low cord syndrome, in order to start the appropriate therapy and avoid future complications.

Neuroparasitic infections: cestodes, trematodes, and protozoans

Parasitic infection of the nervous system can produce a variety of symptoms and signs. Because symptoms of infection are often mild or nonspecific, diagnosis can be difficult. Familiarity with basic epidemiological characteristics and distinguishing radiographic findings can increase the likelihood of detection and proper treatment of parasitic infection of the nervous system. This article discusses the clinical presentation, diagnosis, and treatment for some of the more common infections of the nervous system caused by cestodes, trematodes and protozoans: Echinococcus spp., Spirometra spp. (sparganosis), Paragonimus spp., Schistosoma spp., Trypanosoma spp., Naegleria fowlerii, Acanthamoeba histolytica, and Balamuthia mandrillaris.

Neuroschistosomiasis due to Schistosoma mansoni: a review of pathogenesis, clinical syndromes and diagnostic approaches

Neuroschistosomiasis (NS) is the second most common form of presentation of infection by the trematode, Schistosoma mansoni. Granulomatous inflammatory reaction occurs as a result of schistosome eggs being transmitted to spinal cord or brain via the vascular system, or by inadvertent adult worm migration to these organs. The two main clinical syndromes are spinal cord neuroschistosomiasis (acute or subacute myelopathy) and localized cerebral or cerebellar neuroschistosomiasis (focal CNS impairment, seizures, increased intracranial pressure). Presumptive diagnosis of NS requires confirming the presence of S. mansoni infection by stool microscopy or rectal biopsy for trematode eggs, and serologic testing of blood and spinal fluid. The localized lesions are identified by signs and symptoms, and confirmed by imaging techniques (contrast myelography, CT and MRI). Algorithms are presented to allow a stepwise approach to diagnosis.

Parasitic central nervous system infections in immunocompromised hosts

Immunosuppression due to therapy after transplantation or associated with HIV infection increases susceptibility to various central nervous system (CNS) infections. This article discusses how immunosuppression modifies the presentation, diagnosis, and treatment of selected parasitic CNS infections, with a focus on toxoplasmosis, Chagas disease, neurocysticercosis, schistosomiasis, and strongyloidiasis.

Involvement of central nervous system in the schistosomiasis

The involvement of the central nervous system (CNS) by schistosomes may or may not determine clinical manifestations. When symptomatic, neuroschistosomiasis (NS) is one of the most severe presentations of schistosomal infection. Considering the symptomatic form, cerebral involvement is almost always due to Schistosoma japonicum and the spinal cord disease, caused by S. mansoni or S. haematobium. Available evidence suggests that NS depends basically on the presence of parasite eggs in the nervous tissue and on the host immune response. The patients with cerebral NS usually have the clinical manifestations of increased intracranial pressure associated with focal neurological signs; and those with schistosomal myeloradiculopathy (SMR) present rapidly progressing symptoms of myelitis involving the lower cord, usually in association with the involvement of the cauda esquina roots. The diagnosis of cerebral NS is established by biopsy of the nervous tissue and SMR is usually diagnosed according to a clinical criterion. Antischistosomal drugs, corticosteroids and surgery are the resources available for treating NS. The outcome is variable and is better in cerebral disease.

Spinal cord schistosomiasis: a prospective study of 63 cases emphasizing clinical and therapeutic aspects

A prospective study was conducted on 63 patients with schistosomal myeloradiculopathy admitted to a university hospital in Brazil. They were evaluated according to a protocol and treated with corticosteroid and praziquantel. The disease, in general, presented as a lower cord syndrome of acute progression characterized by motor, sensory and autonomic dysfunctions. The severity of the clinical picture was different among the patients, but the symptoms were quite constant. Cerebrospinal fluid examination showed an inflammatory pattern with or without eosinophils and/or IgG against schistosomal antigens. The most frequent alterations detected by imaging methods were enlargement of the medullary cone and of the roots of the cauda equina. Schistosome egg counts suggested a low parasite burden in 71.6% of the cases. Outcome was favorable in 38 (60.3%) patients and improvement usually started within the first 48 h after commencing on corticoid and was faster during the early period of treatment.

Esquistossomose medular: análise de 80 casos

O objetivo deste estudo é analisar dados clínicos e laboratoriais de 80 casos de esquistossomose medular (EM) que possam contribuir para melhorar o diagnóstico e tratamento dessa doença. Em 59 pacientes o estudo foi de maneira prospectiva, em 79 pacientes o diagnóstico foi catalogado como altamente provável, presuntivo, baseado em critérios clínico e laboratoriais. Em um paciente houve confirmação anatomo-patológica. Houve predominância do sexo masculino (63,7%), faixa etária entre 21 e 40 anos (63,7%), procedência nordestina (85%), trabalhador em construção civil (31,2%), esforço abdominal prévio (57,5%), início subagudo (61,2%), forma clínica mielorradiculítica e lesão no cone medular e cauda equina (72,5%). O estudo do líquido cefaloraquidiano mostrou pleocitose e taxas elevadas de proteínas em 100% dos casos, da gamaglobulina em 76.5%, positividade de reações imunológicas específicas (imunofluorescência e/ou ELISA) em 100% dos casos (titulo médio de 1/16 e 61u/dl, respectivamente). Costicosteróides e drogas esquistossomicidas foram administrados em todos os pacientes com evolução satisfatória em 80% dos casos.

Diagnóstico da esquistossomose medular: contribuição da ressonância magnética e eletroneuromiografia

OBJETIVO: Analisar os resultados obtidos pela ressonância magnética (RM) e eletroneuromiografia (ENMG) em pacientes com diagnóstico de esquistossomose medular (EM). MÉTODO: Foram analisadas 18 RM da coluna vertebral tóraco-lombar e 24 ENMG dos membros superiores e inferiores de pacientes com diagnóstico definido ou altamente provável de EM nas suas formas clínicas mielorradiculítica e mielítica. RESULTADOS: Entre as 18 RM realizadas, 16 (88,8%), mostraram alterações caracterizadas por imagens hipointensas em aquisições pesadas em T1, hiperintensas em T2, com captação heterogênea do contraste gadolínico e/ou realce das meninges e cauda equina. Entre as 24 ENMG, 23 (95,8%) mostraram quadro de multirradiculopatia bilateral das raízes nervosas L2, L3, L4, L5, S1, S2, assimétrico em 10 casos (41,6%). CONCLUSÃO: A RM e a ENM demonstraram ser exames úteis para o diagnóstico da EM ao revelarem anormalidades que se repetiram sob um determinado padrão em 88,8% e 95,8% dos casos, respectivamente. Apesar de não terem especificidade para a EM, estes procedimentos devem ser realizados rotineiramente com o objetivo de fortalecer o diagnóstico presuntivo desta doença.

Experimental neuroschistosomiasis: inadequacy of the murine model

Neuroschistosomiasis is rarely observed in human pathology, but it is of considerable importance. To investigate its pathogenesis, consequences and response to treatment, an experimental model would be desirable, but is not yet available, in spite of a few indications of a suitable mouse model in the literature. Severe, recent and late Schistosoma mansoni infections in outbred and inbred strains of mice revealed widespread distribution of parasite eggs in several organs, but only exceptionally did eggs reach the encephalus, thus revealing the inadequacy of the mouse as an experimental model for neuroschistosomiasis.

Spinal cord schistosomiasis in children: analysis of seven cases

We describe seven cases of children (ages 2 to 14 years) with myeloradiculopathy caused by infection with S. mansoni. None of them presented hepatosplenic involvement and one presented an intestinal picture. The myeloradicular and pseudotumoral forms were observed in four and three patients, respectively. Comparing the reports in the literature, we found that the pseudotumoral form is more similarly frequent among children than in adults, while the myelitic and myeloradicular forms are the most frequent and distributed across all age groups. Diagnosis is based on clinical and epidemiological findings in association with laboratory tests. The diagnosis was confirmed by the presence of S. mansoni eggs in feces (5 cases) and / or the positivity in specific immunological tests (5 cases) associated with a cerebrospinal fluid inflammatory pattern with presence of eosinophils (between 1 and 24%). Magnetic resonance image, although it does not enable an etiological diagnosis, helped to confirm the form and spinal cord level of the lesion.

Estimation of the local synthesis of immunoglobulin G (IgG) in the central nervous system of patients with spinal cord schistosomiasis by the IgG index

By analogy with other infections of the central nervous system (CNS), it is believed that schistosomal myeloradiculopathy (SMR) is an entity that may involve a mild-to-moderate degree of impairment of the blood-brain barrier along with intrathecal synthesis of antibodies. The first of these aspects is obvious but the second has not been clearly demonstrated. This study was undertaken in Brazil with the aim of investigating the production of immunoglobulin G (IgG) within the CNS in patients with SMR, by the determination of the cerebrospinal fluid (CSF) IgG index. The study population included 54 patients with SMR, evaluated prospectively. The CSF IgG index was increased in 43 of them (80%). Preliminary results from our laboratory suggest that these antibodies are reactive against Schistosoma mansoni antigens. Thus, this finding also suggests that this index may be useful in the differential diagnosis of SMR.

Spinal cord schistosomiasis. A report of 2 cases and review emphasizing clinical aspects

Schistosomal myeloradiculopathy (SMR) is a severe and little known form of presentation of schistosomiasis mansoni and hematobic schistosomiasis. The literature concerning the entity is scarce, and most publications are limited to isolated case reports. Thus, to consolidate and analyze the knowledge currently available about the disease, I reviewed 231 cases, with emphasis on clinical aspects. Although variations occur, in most cases the clinical picture of SMR is highly suggestive in individuals with epidemiologic antecedents of the infection. Thus, a patient with SMR is usually a young male with no other manifestations of schistosomal infection who presents with lumbar pain, often of a radicular nature, soon followed by weakness and sensory loss of rapid progression in the lower limbs associated with autonomic dysfunction, particularly bladder dysfunction. The most suggestive elements of the entity, and therefore of higher diagnostic value, are the low localization of the spinal cord lesion, the acute or subacute onset of the disease, and the association of manifestations due to medullary and radicular involvement. SMR is commonly classified into clinical or anatomoclinical forms. However, I observed no consensus in this classification even in terms of the terminology used. The analysis performed in this review permitted the introduction of a new concept not yet reported in the literature regarding the possibility that the disease consists of a continuous spectrum, with asymptomatic egg laying in the spinal cord at 1 end of the spectrum and devastating forms at the other end, with most cases occupying an intermediate position and with the various types of damage overlapping and associated to different degrees. This concept applies not only to different patients but also to the same patient at different stages of the disease. Chemical and cytomorphologic examination of cerebrospinal fluid (CSF) almost always revealed mildly or moderately increased total protein concentration and predominantly lymphocytic pleocytosis. Eosinophils, the least nonspecific finding, were detected in the CSF of less than half (40.8%) the patients. Myelography and computed tomography-myelography were altered in 63.3% of cases, but this proportion may be an overestimate. The most frequent changes were images of a filling defect due to expansion of the spinal cord and were almost always demonstrated by the 2 imaging modalities. Although still few in number, early reports suggest that magnetic resonance imaging is more sensitive; however, the changes are also nonspecific, such as those revealed by myelography and computed tomography-myelography. Parasite eggs were demonstrated frequently in a biologic specimen (88.3%), but difficulty in detection was not uncommon. Peripheral blood eosinophilia was detected in 64.5% of patients and represented a nonspecific finding. The detection of anti-Schistosoma antibodies in the serum or CSF was also frequent (94.9% and 84.8%, respectively). The presence of anti-Schistosoma antibodies in serum is of limited value for the diagnosis of schistosomiasis in general, especially among individuals living in endemic areas; however, their quantification in the CSF has proved to be promising for diagnosis in the few studies conducted for this purpose. The large number of variables concerning treatment (such as drugs used and duration of disease at the beginning of treatment), together with the relative lack of information about the natural history of the disease, limit the analysis of aspects related to treatment and prognosis. Nevertheless, it was possible to conclude that corticosteroids and antischistosomotic drugs have a favorable effect on disease outcome and should be administered as early as possible. In addition to early treatment, factors linked to the disease itself affect prognosis. The new cases of SMR reported here are typical and illustrate the data discussed in this literature survey.

Statistical analysis of highly skewed immune response data

This paper considers methods of statistical analysis for highly skewed immune response data. Observations from population studies of immunological variables are rarely normally distributed between individuals; typically the distribution shows extreme levels of skewness. In some situations, skewness remains considerable even after transforming the data. Using resampling techniques, applied to several actual datasets of ELISA assay data, we consider the robustness of normal parametric methods, e.g. t tests and linear regression. Despite the skewness of the transformed data, we demonstrate that such methods are quite robust depending on the number of observations, type of analysis and severity of skewness. We also illustrate how bootstrap resampling can be used to provide a valid alternative method of analysis that can be used either for checking normal parametric analysis or as a direct method of analysis. We illustrate this combined approach by analysing real data to test for association between human serum antibodies to malaria merozoite surface proteins, MSP1 and MSP2, and resistance to clinical malaria, and confirm the protective effect of antibodies to MSP1 and demonstrated a similar protective effect for some antibodies to MSP2.