Diagnostic criteria and case definitions for abdominal angiostrongyliasis: a systematic review from the Brazilian experience.

Although rare, Angiostrongylus costaricensis infection may be a more prevalent etiology of inflammatory bowel disease than ulcerative colitis and Chron's disease in endemic areas in Central and South America. The present study reviewed the occurrence of A. costaricensis in Brazil, its clinical presentation and pathology; and proposed diagnostic criteria and case definitions for abdominal angiostrongyliasis (AA). Southern and southeastern Brazilian regions are the main endemic areas, and AA affects both genders and all age groups. A review of all 23 published reports of 51 Brazilian patients highlighted the following features that were subsequently classified as minor diagnostic criteria: abdominal pain, palpable mass in the right lower abdominal quadrant, history of exposure, ileocecal tumor, and intestinal perforation with wall thickening. Proposed major criteria include right lower quadrant abdominal pain, blood eosinophilia, positive serology (antibody detection), intense eosinophilic infiltration that involves all strata of the intestinal wall, eosinophilic granulomatous reaction, and eosinophilic vasculitis. In addition to the definitions of suspected and possible cases according to increasing strength of evidence of this infection, demonstration of worms/eggs/larvae in tissues or Angiostrongylus DNA in tissues or serum are required for a confirmed diagnosis. The application of the proposed criteria and definitions may improve patient management, epidemiologic surveillance, and identification of new endemic areas.

Relationship between histopathological lesions and oxidative stress in mice infected with Angiostrongylus costaricensis.

This study describes changes in oxidative stress (OS) parameters in mice experimentally infected with Angiostrongylus costaricensis, which causes abdominal angiostrongyliasis. For this, 28 Swiss mice were used, divided into two groups (G1 and G2), with 14 animals each. Of these, eight were infected with ten infective larvae each, by gavage, and six were used as a control group. Mice from G1 and G2 were euthanized at 14 days and 24 days post-infection, respectively. Tissue samples were used for histopathological analysis and blood (serum) samples were taken to assess the levels of proteins, non-protein thiols (NPTs) and nitric oxide (NO), from centrifugation and subsequent collection of aliquots of the supernatant. Among OS parameters, infected mice in both groups had higher NO levels than the control group, due to the presence of: eosinophil infiltrate in the liver and intestine; pancreatitis; and intestinal granuloma. However, the infected mice of both groups showed a reduction in the levels of NPTs, in relation to the control group, due to the presence of: eosinophilic infiltrate in the liver and intestine; and intestinal granuloma. Our results suggest that A. costaricensis infection has important effects on the intestine, liver and pancreas, and the analyses were performed from the tissue of these organs. The mechanisms for these changes are related to the decrease in the body's main antioxidant defences, as demonstrated by the reduction of NPTs, thus contributing to the development of more severe tissue damage. Thus, the objective of the present study was to evaluate the relationship between histopathological lesions and markers for OS.

Molecular diagnosis of abdominal angiostrongyliasis by PCR using serum samples.

Abdominal angiostrongyliasis (AA) is a zoonotic disease caused by the nematode Angiostrongylus costaricensis, which is endemic in southern Brazil. Humans become infected by ingesting third-stage (L3) larvae and are considered accidental hosts since neither eggs nor first-stage (L1) larvae are found in feces. The definitive diagnosis can be made by histopathologic examination of surgical specimens or intestinal biopsies. The present study assessed the use of PCR to carry out the molecular detection of AA from serum samples. A total of 62 human serum samples were divided into three groups: (i) 28 serum samples from human patients with presumptive histopathological diagnosis of AA; (ii) 23 serum samples from individuals with unknown serology for AA; (iii) 11 serum samples from patients that suffered from different parasitosis were included. The serum samples were initially tested by in-house indirect ELISA and then by PCR. A total of 14 samples were positive by ELISA, and 6 were positive by PCR. Six samples that were negative by ELISA were positive by PCR. Amplicons were sequenced, and Angiostrongylus DNA was confirmed. We conclude that PCR amplification can be used to confirm Angiostrongylus DNA in serum, which is especially important in cases where antibody levels are too low to be detected. It may also serve as a useful target for survey studies.

Leukogram and cortisol parameters in Swiss mice experimentally infected with Angiostrongylus costaricensis.

This study describes changes in haematological parameters, cytokine profile, histopathology and cortisol levels in Swiss mice experimentally infected with Angiostrongylus costaricensis. Twenty-eight Swiss mice were divided into two groups (G1 and G2) of 14 animals each. In each group, eight animals were infected orally with ten third-stage larvae of A. costaricensis and six were used as a control group. The mice of groups G1 and G2 were sacrificed 14 and 24 days after infection, respectively. Samples were collected for histopathological and haematological analyses and determination of the cytokine profile and cortisol levels. Granulomatous reaction, eosinophilic infiltrate and vasculitis in the intestinal tract, pancreas, liver and spleen were observed with varying intensity in infected animals. Our results showed that the mice developed normocytic and hypochromic anaemia, and that the histopathological lesions caused by the experimental infection influenced increases in cortisol, neutrophil and monocyte levels. In addition to this, we detected increased interleukin-6 and tumour necrosis factor alpha levels in the infected animals.

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

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

Abdominal angiostrongyliasis: pathologic findings in Swiss mice infected with different doses of Angiostrongylus costaricensis.

Abdominal angiostrongyliasis is caused by Angiostrongylus costaricensis, the definitive and intermediate hosts of which are wild rodents and terrestrial molluscs, respectively. Humans are accidental hosts and can be infected by ingesting the third-stage (infective) larvae (L3). It remains unclear whether the number of L3 inoculated is related to lesion severity. Our aim was to analyse histopathological alterations in Swiss mice infected with different doses of A. costaricensis. Thirty-two mice were randomly divided into four groups (n = 8/group): uninfected, control mice; mice infected with a low dose (five L3); mice infected with an intermediate dose (15 L3); and mice infected with a high dose (30 L3). The frequency of intestinal thrombi, splenitis, eggs/larvae, hepatic infarction and acute pancreatitis differed among the groups, the last being considered a significant finding. We conclude that different infective doses alter the histopathological aspects of the infection in Swiss mice, those aspects being more pronounced at medium and high doses, with no effect on the development of the disease. This experimental model shows that the parasite life cycle can be maintained in Swiss mice through the inoculation of a low dose (five L3).

Invasive slug Meghimatium pictum (Stoliczka, 1873) infected by Angiostrongylus costaricensis Morera & Céspedes, 1971, and the possible risk of human infection associated with grape consumption.

Many molluscs may be infected with angiostrongylid larvae. Following the histopathological diagnosis of abdominal angiostrongyliasis in a grape farmer from southern Brazil, molluscs in the area were investigated. During a nocturnal search, 245 specimens of slugs were collected and identified as the invasive Chinese slug Meghimatium pictum. Angiostrongylus costaricensis worms were recovered from mice that were experimentally infected with larvae obtained from 11 (4.5%) of the molluscs. This study presents the first report of M. pictum being identified as an intermediate host for A. costaricensis. Most of the slugs were collected from grape plants, which suggests that transmission may be associated with grape consumption.

Shedding of Angiostrongylus costaricensis larvae in the faeces of Swiss mice experimentally infected with different infective doses.

Abdominal angiostrongyliasis is an endemic zoonosis in southern Brazil caused by the nematode Angiostrongylus costaricensis, which uses terrestrial molluscs as intermediate hosts and wild rodents as final hosts. Humans can be infected by ingesting infectious A. costaricensis larvae. To date, correlations between shedding of first-stage larvae (L1) and different infective doses of third-stage larvae (L3) have not been elucidated. The aim of this study was to assess L1 faecal shedding levels in Swiss mice experimentally infected with different doses of A. costaricensis L3 and to determine whether infective doses are related to mortality. Thirty-two male Swiss mice were divided evenly into a non-infected control (NI-Con); low-dose infection (LD-Inf); medium-dose infection (MD-Inf) and high-dose infection (HD-Inf) groups infected with 0, 5, 15 and 30 A. costaricensis L3, respectively. Faecal samples were collected from each animal, starting at day 20 post infection. HD-Inf mice had greater faecal L1 shedding levels than LD-Inf mice, but not a significantly shortened survival. In conclusion, infective doses of A. costaricensis L3 affect L1 shedding levels without altering mortality in Swiss mice.

Abdominal Angiostrongyliasis: A Presentation of Eosinophilic Granulomatous Colitis.

We present a case of a 4-year-old girl with abdominal angiostrongyliasis who presented with persistent fevers, hepatosplenomegaly, acute abdominal pain, and eosinophilia. Computed tomography scan identified thickening of the ascending colon with a narrowed lumen. Endoscopic evaluation revealed ulcerations and erythema in the ascending colon. The microscopic findings in biopsies included active chronic inflammation with prominent eosinophils and granulomas. A subset of granulomas contained the eggs of Angiostrongylus costaricensis. The definitive method of diagnosing A costaricensis is histology; peripheral blood serology has low specificity and the stool from infected patients does not contain eggs or larvae. Pathologists from endemic regions (Central and South America) are familiar with the typical histologic changes; however, because of increasing global travel, all pathologists should become familiar with A costaricensis, which may mimic common gastrointestinal diseases such as Crohn's disease, appendicitis, and Meckel's diverticulum.

Characterisation of the vascular pathology in Sigmodon hispidus (Rodentia: Cricetidae) following experimental infection with Angiostrongylus costaricensis (Nematoda: Metastrongylidae)

BACKGROUND Angiostrongylus costaricensis is a nematode that causes human abdominal angiostrongyliasis, a disease found mainly in Latin American countries and particularly in Brazil and Costa Rica. Its life cycle involves exploitation of both invertebrate and vertebrate hosts. Its natural reservoir is a vertebrate host, the cotton rat Sigmodon hispidus. The adult worms live in the ileo-colic branches of the upper mesenteric artery of S. hispidus, causing periarteritis. However, there is a lack of data on the development of vasculitis in the course of infection. OBJECTIVE To describe the histopathology of vascular lesions in S. hispidus following infection with A. costaricensis. METHODS Twenty-one S. hispidus were euthanised at 30, 50, 90 and 114 days post-infection (dpi), and guts and mesentery (including the cecal artery) were collected. Tissues were fixed in Carson’s Millonig formalin, histologically processed for paraffin embedding, sectioned with a rotary microtome, and stained with hematoxylin-eosin, resorcin-fuchsin, Perls, Sirius Red (pH = 10.2), Congo Red, and Azan trichrome for brightfield microscopy analysis. FINDINGS At 30 and 50 dpi, live eggs and larvae were present inside the vasa vasorum of the cecal artery, leading to eosinophil infiltrates throughout the vessel adventitia and promoting centripetal vasculitis with disruption of the elastic layers. Disease severity increased at 90 and 114 dpi, when many worms had died and the intensity of the vascular lesions was greatest, with intimal alterations, thrombus formation, iron accumulation, and atherosclerosis. CONCLUSION In addition to abdominal angiostrongyliasis, our data suggest that this model could be very useful for autoimune vasculitis and atherosclerosis studies.

The white-nosed coati (Nasua narica) is a naturally susceptible definitive host for the zoonotic nematode Angiostrongylus costaricensis in Costa Rica.

Angiostrongylus costaricensis (Strongylida, Angiostrongylidae) is a roundworm of rodents, which may cause a severe or fatal zoonosis in several countries of the Americas. A single report indicated that the white-nosed coati (Nasua narica), acts as a potential free-ranging wildlife reservoir. Here we investigated the prevalence and features of A. costaricensis infection in two procyonid species, the white-nosed coati and the raccoon (Procyon lotor) from Costa Rica to better understand their possible role in the epidemiology of this zoonotic infection. Eighteen of 32 (56.2%) white-nosed coatis collected between July 2010 and March 2016 were infected with A. costaricensis but none of 97 raccoons from the same localities were diagnosed with this infection. First-stage larvae of A. costaricensis were obtained from feces of 17 fresh white-nosed coati carcasses by Baermann technique. Parasite identity was confirmed by morphology, histology and molecular characterization of target genes. These data demonstrate that the white-nosed coati is a naturally susceptible definitive host for A. costaricensis in Costa Rica contrary to findings in the raccoon.

First report of a naturally patent infection of Angiostrongylus costaricensis in a dog.

Angiostrongylus costaricensis is the zoonotic agent of abdominal angiostrongyliasis in several countries in North and South America. Rodents are recognized as the main definitive hosts of A. costaricensis, but other wildlife species can develop patent infections. Although, several human cases have been described in the literature, the role of domestic animals in the epidemiology of the infection is not clear. Here we review the literature available on A. costaricensis in mammals and describe the first confirmed fatal case of abdominal angiostrongyliasis in a 4-month-old dog, presented with intestinal perforation, peritonitis and faecal shedding of first-stage larvae. Parasite identity was confirmed by morphology, histology and molecular characterization of target genes. This is the first record of a naturally infected dog acting as a definitive host for A. costaricensis. These data suggest that dogs may potentially spread this parasite in urbanized areas.

An indirect immunofluorescence antibody test employing whole eggs as the antigen for the diagnosis of abdominal angiostrongyliasis

Abdominal angiostrongyliasis is a potentially fatal zoonotic disease with a broad geographical distribution throughout Central and South America. This study assessed the performance of Angiostrongylus costaricensis eggs as the antigen in an indirect immunofluorescence assay for the determination of parasite-specific IgG and IgG1 antibodies. For prevalence studies, an IgG antibody titre > 16 was identified as the diagnostic threshold with the best performance, providing 93.7 percent sensitivity and 84.6 percent specificity. Cross reactivity was evaluated with 65 additional samples from patients with other known parasitic infections. Cross reactivity was observed only in samples from individuals infected with Strongyloides stercoralis. For clinical diagnosis, we recommend the determination of IgG only as a screening test. IgG1 determination may be used to increase the specificity of the results for patients with a positive screening test.

Impactos socioeconômicos de uma doença emergente / Socioeconomic impacts of an emerging disease

Em 1995, ocorreu uma praga de lesmas identificadas como Sarasinula linguaeformis (Semper, 1885), que prejudicou as lavouras situadas entre os municípios de Nova Itaberaba e Planalto Alegre, no oeste do estado de Santa Catarina, Brasil. Neste artigo analisamos os impactos socioeconômicos provocados pela ocorrência desta praga, que sinalizou a possibilidade, posteriormente verificada, da emergência de casos de angiostrongilíase abdominal. Os dados foram coletados através de observação do estudo soroepidemiológico realizado na região durante o período de agosto de 2000 a agosto de 2001 pela equipe de pesquisa da Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), entrevistas com técnicos da Empresa de Pesquisa Agropecuária e Extensão Rural de Santa Catarina S.A. (Epagri-SC) e com cinquenta famílias locais. Para avaliar esses impactos, elaboramos algumas categorias de análise, como: prejuízo econômico; medidas preventivas e mudança de hábitos; estigma e preconceito, que surgiram à luz das narrativas dos sujeitos entrevistados. Ficou evidente a necessidade de se procederem a estudos sobre os aspectos sociológicos dos problemas epidemiológicos, além dos estritamente médico-sanitários.

In 1955 a population explosion of the slug Sarasinula linguaeformis (Semper, 1885) damaged crop plantations in the municipalities of Nova Itaberaba and Planalto Alegre, western of Santa Catarina State, Brazil. In this article we analyze the socioeconomic impacts caused by the emergence of this plague, which raised the suspicion, eventually confirmed, of the occurrence of human cases of abdominal angyostrongiliasis. The data were collected through the observation of a serological study during the period of August 2000 to August 2001 by a research team from the Catholic University of Rio Grande do Sul (PUCRS) together with field technicians from the Empresa de Pesquisa Agropecuária e Extensão Rural de Santa Catarina S.A. (Epagri-SC), and with the members of 50 local families. In order to analyze these impacts, we elaborated several analytical categories as economic losses; preventive measures, habit change and social prejudice, that emerged from the narratives of the residents interviewed. It became evident the need for sociological analyses of epidemiological problems, in addition to strictly medico-sanitary considerations.

Worms, slugs and humans: the medical and popular construction of an emerging infectious disease / Vermes, caramujos e humanos: as construções médica e popular de uma doença infecciosa emergente

The identification of the worm Angiostrongylus costaricensis parasitizing land snails and humans in Southern Brazil suggests under-diagnosis and under-notification of patients with abdominal angiostrongyliasis. This article analyzes how the concept of abdominal angiostrongyliasis was constructed in different ways in Costa Rica and Brazil and how these changes affected the understanding of its clinical and epidemiological diagnosis. The research shows that abdominal angiostrongyliasis is, de facto, a sociocultural construct, although the parasites and vectors are real. The analisys also shows the importance of an interdisciplinary approach for understanding disease.

A identificação do verme Angiostrongylus costaricensis em humanos e caramujos, no sul do Brasil, sugere a ocorrência de subdiagnóstico e subnotificação de pacientes com angiostrongilíase abdominal. O artigo analisa as diferentes construções do conceito de angiostrongilíase abdominal na Costa Rica e no Brasil e a influência dessas variações em seu diagnóstico clínico e epidemiológico. Demonstra que a angiostrongilíase abdominal é, de facto, um constructo sociocultural, embora parasitas e vetores sejam reais. Também destaca a importância da abordagem interdisciplinar para a compreensão da doença.

Use of heterologous antigens for the immunodiagnosis of abdominal angiostrongyliasis by an enzyme-linked immunosorbent assay

Angiostrongylus costaricensis has a broad geographic distribution spanning from North to South America and the infections of vertebrates with this nematode can result in abdominal complications. Human infections are diagnosed by histological or serological methods because the isolation of larvae from feces is not feasible, as most parasites become trapped in intestinal tissues due to intense eosinophilic inflammation. Because A. costaricensis is difficult to maintain in the laboratory, an immunodiagnostic IgG enzyme-linked immunosorbent assay (ELISA) using antigens from the congeneric Angiostrongylus cantonensis species was evaluated against a panel of serum samples from patients who were histologically diagnosed with A. costaricensis infections. Sera from uninfected individuals and individuals infected with other parasites were used as controls. The sensitivity and specificity of the assay were estimated at 88.4 percent and 78.7 percent, respectively. Because the use of purified or cloned antigens has not been established as a reliable diagnostic tool, the use of heterologous antigens may provide a viable alternative for the development of an ELISA-based immunodetection system for the diagnosis of abdominal angiostrongyliasis.

Abdominal angiostrongyliasis: report of two cases with different clinical presentations / Angiostrongilíase abdominal: relato de dois casos com diferentes apresentações clínicas

Abdominal angiostrongyliasis is a sporadic infectious disease caused by the nematode Angiostrongylus costaricensis. It usually presents as acute abdomen, secondary to mesenteric ischemia, and pronounced eosinophilia. In some cases its course is insidious and transient, and the diagnosis is suspicious. The disease is confirmed by the detection of A. costaricensis elements in surgical specimen. The treatment is supportive, with avoidance of antihelminthic administration due to a possible erratic migration followed by worsening of the disease. We report two cases, both with intense eosinophilia and serum IgG-ELISA positive to A. costaricensis. The first case presented ileal perforation and was surgically treated. The second one showed hepatic nodules at ultrasound and was only symptomatically treated, evolving to an apparent protracted resolution. These two cases exemplify different clinical forms of the disease, one of them with liver involvement.

A angiostrongilíase abdominal é doença esporádica decorrente da infecção pelo nematódeo Angiostrongylus costaricensis. Costuma manifestar-se como abdome agudo secundário a isquemia mesentérica, além de marcada eosinofilia. Pode também apresentar-se de forma insidiosa e transitória, exigindo alta suspeita clínica para o diagnóstico. A doença é confirmada pela identificação de elementos do A. costaricensis em peças cirúrgicas. O tratamento é apenas de suporte, devendo-se evitar o uso de anti-helmínticos pela possibilidade de migração errática do verme com piora do quadro. Aqui foram apresentados dois casos, ambos com acentuada eosinofilia e ELISA-IgG sérico positivo para A. costaricencis. O primeiro caso cursou com perfuração ileal e foi tratado cirurgicamente. O segundo caso apresentou nódulos hepáticos ao ultrassom e foi tratado sintomaticamente, evoluindo para lenta resolução. Estes dois casos exemplificam diferentes formas de apresentação clínica da doença, uma delas com envolvimento hepático.

Individual serological follow-up of patients with suspected or confirmed abdominal angiostrongyliasis

Abdominal angiostrongyliasis (AA) is a zoonotic nematode infection caused by Angiostrongylus costaricensis, with widespread occurrence in the Americas. Although the human infection may be highly prevalent, morbidity is low in Southern Brazil. Confirmed diagnosis is based on finding parasitic structures in pathological examination of biopsies or surgical resections. Serology stands as an important diagnostic tool in the less severe courses of the infection. Our objective is to describe the follow up of humoral reactivity every 2-4 weeks up to one year, in six individuals with confirmed (C) and ten suspected (S) AA. Antibody (IgG) detection was performed by ELISA and resulted in gradually declining curves of reactivity in nine subjects (56 percent) (4C + 5S), that were consistently negative in only three of them (2C + 1S) after 221, 121 and 298 days. Three individuals (2C + 1S) presented with low persistent reacitivity, other two (1C + 1S) were serologically negative from the beginning, but also presenting a declining tendency. The study shows indications that abdominal angiostrongyliasis is usually not a persistent infection: although serological negativation may take many months, IgG reactivity is usually declining along time and serum samples pairing may add valuable information to the diagnostic workout.