Treatment with mebendazole is not associated with distal migration of adult Angiostrongylus costaricensis in the murine experimental infection

Abdominal angiostrongyliasis is a zoonotic infection produced by a metastrongylid intra-arterial nematode, Angiostrongylus costaricensis. Human accidental infection may result in abdominal lesions and treatment with anti-helminthics is contra-indicated because of potential higher morbidity with excitement or death of worms inside vessels. To evaluate the effect of mebendazole on localization of the worms, male Swiss mice, 5 week-old, were infected with 10 third stage larvae per animal. Twelve infected mice were treated with oral mebendazol, at 5 mg/kg/day, for 5 consecutive days, begining 22 days after inoculation. As control groups, 12 infected but non-treated mice and other 12 non-infected and non-treated mice were studied. The findings at necropsy were, respectively for the treated (T) and control (C) groups: 92% and 80% of the worms were inside the cecal mesenteric arterial branch; 8% and 10% were located inside the aorta. Only in the group C some worms (10%) were found inside the portal vein or splenic artery. These data indicate that treatment with mebendazole does not lead to distal or ectopic migration of A. costaricensis worms.

Environmental contamination by Toxocara sp. eggs in Ribeirão Preto, São Paulo State, Brazil

Toxocariasis is a zoonosis mainly caused by Toxocara canis, an intestinal nematode of dogs. Man acquires the infection through accidental ingestion of viable eggs, and the toxocariasis clinical manifestations may vary from an asymptomatic infection up to the Visceral Larva Migrans syndrome. Seventy eight public squares of Ribeirão Preto, São Paulo, Brazil, including Bonfim Paulista district were visited aiming to evaluate the soil contamination by Toxocara eggs. The squares were divided in five different areas corresponding to the Sanitary Districts of the city. From May to December 2003, soil samples weighting about 250 g each were collected from five distinct sites of each public square. The laboratorial analysis was done by centrifugal-flotation techniques in magnesium sulphate solutions with 5% of potassium iodide (d = 1.33) and zinc sulphate (d = 1.20), and by the sedimentation- flotation in conic chalices with zinc sulphate (d = 1.20). Toxocara sp. eggs were found on 16 (20.5%) squares, with the lowest prevalence (12%) at the central area. From these results, it is expected that the legal authority will adopt protection measures for the city public areas, reducing thus the contamination risk by Toxocara sp. eggs.

Human infection by Angiostrongylus costaricensis in Venezuela: first report of a confirmed case

A proven case of human infection caused by Angiostrongylus costaricensis is reported for the first time in Venezuela. The patient was a 57-year-old female surgically operated because of signs of peritonitis with a palpable mass at the lower right quadrant of the abdomen. WBC count reported 16,600 cells/mm³, with 46% eosinophils. The tumoral aspect of ileocolic area and peritoneal lymph nodes prompted the resection of a large area of the terminal ileum, cecum, part of the ascending colon and a small part of the jejunum, where a small lesion was found. The pathology showed thickened areas of the intestinal wall with areas of hemorrhage and a perforation of the cecum. Histology showed intense eosinophil infiltration of the whole intestinal wall, granulomas with giant cells and eosinophils. Some of the granuloma surrounded round or oval eggs with content characterized by a large empty area, cells or embryo in the center, and sometimes nematode larvae. A cross section of an adult nematode worm was observed inside a branch of mesenteric artery. The intestinal affected area, the characteristics of the lesions, the presence of eggs in the submucosa with nematode larvae inside, and the observation of a nematode inside a mesenteric artery, makes sufficient criteria for the diagnosis of an infection by Angiostrongylus costaricensis.

Abdominal angiostrongyliasis: report of two cases with different clinical presentations

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.

Behavioral changes in Rattus norvegicus experimentally infected by Toxocara canis larvae

Toxocara canis is a common canine nematode parasite and one of its possible transmission mechanisms is the predation of infected rodents by canids. Fifty Rattus norvegicus were used to study behavioral alterations in rodents infected by T. canis larvae. The rats were divided into three groups: G1, 20 rats infected with 300 T. canis eggs; G2, 20 rats infected with 2,000 T. canis eggs; and G3, 10 non-infected rats. Thirty and 60 days post-infection, rats from all the groups were submitted to an open-field apparatus for five min and subsequently, to an elevated plus-maze apparatus, again for five min. The data obtained indicated improvement in mobility (total locomotion time and rearing frequency) and exploratory behavior in infected rats, principally in G2, which provides some support for the hypothesis that behavioral alterations in rodents infected by Toxocara canis larvae enhance the transmission rate of this ascarid to dogs.

PARASITOLOGICAL AND MOLECULAR DIAGNOSIS IN EXPERIMENTAL Strongyloides venezuelensis INFECTION

Strongyloides venezuelensis is a parasitic nematode of rats which is frequently used as a model to study human and animal strongyloidiasis. The aim of this study was to evaluate the correlation between parasitological and molecular diagnosis in Strongyloides venezuelensis infection. PCR assays were used to detect S. venezuelensis DNA in fecal samples obtained from experimentally infected Rattus norvegicus. The results showed a higher sensitivity of the PCR assay in detecting the infection compared to parasitological methods.

EFFECT OF Bifidobacterium animalis ON MICE INFECTED WITH Strongyloides venezuelensis

The administration of viable Bifidobacterium animaliswas tested to induce resistance against Strongyloides venezuelensis infection in mice. Effects on parasite burden, worm length, egg output, and intestinal mucosal histology were evaluated. The oral administration of B. animalis, strain 04450B, starting 14 days before the inoculation of nematode larvae significantly decreased the worm burden and egg output. In probiotic treated animals, the percent reduction of adult worms in the intestine was of 33% and the reduction of egg production was of 21%, compared with those of the control group. The duodenum villous height and villous/crypt ratio were significantly higher in probiotic-treated mice, indicating that this group could be experiencing less intestinal damage. The present findings revealed that the administration of B. animalis for the amelioration of host response to nematode infections is biologically plausible and could have some potential for impacting public health. Meanwhile, further study is needed to delineate the nature and identity of the factor(s) involved in these beneficial effects.

PREVALENCE OF Calodium hepaticum (SYN. Capillaria hepatica) IN Rattus norvegicus IN THE URBAN AREA OF RIO DE JANEIRO, BRAZIL

The nematode Calodium hepaticum (syn. Capillaria hepatica) is a zoonotic helminth found mainly infecting rats. It was studied the prevalence of C. hepaticum infection in Rattus norvegicus in an urban area of Rio de Janeiro (Brazil), with low urban planning and sanitation. The presence of C. hepaticum was identified through visible yellowish-white lesions in liver tissue and histological analyses. The total prevalence of infection was 45%, with no significant differences between sex and age. The presence of infected rodents near the peridomestic area poses substantial risk to human health.

MEMBRANE FRACTIONS FROM Strongyloides venezuelensis IN THE IMMUNODIAGNOSIS OF HUMAN STRONGYLOIDIASIS

Strongyloides venezuelensis is a parasitic nematode of rodents frequently used to obtain heterologous antigens for the immunological diagnosis of human strongyloidiasis. The aim of this study was to evaluate membrane fractions from S. venezuelensis for human strongyloidiasis immunodiagnosis. Soluble and membrane fractions were obtained in phosphate saline (SS and SM) and Tris-HCl (TS and TM) from filariform larvae of S. venezuelensis. Ninety-two serum samples (n = 92) were obtained from 20 strongyloidiasis patients (Group I), 32 from patients with other parasitic diseases (Group II), and 40 from healthy individuals (Group III), and were analyzed by enzyme-linked immunosorbent assay (ELISA). Soluble fractions (SS and TS) showed 90.0% sensitivity and 88.9% specificity, whereas the membrane fractions (SM and TM) showed 95.0% sensitivity and 94.4% specificity. The present results suggest the possible use of membrane fractions of S. venezuelensis as an alternative antigen for human strongyloidiasis immunodiagnosis.

Angiostrongylus costaricensis and the intermediate hosts: observations on elimination of L3 in the mucus and inoculation of L1 through the tegument of mollucs

Human accidental infection with Angiostrongylus costaricensis may result in abdominal disease of varied severity. Slugs from the Veronicellidae family are the main intermediate hosts for this parasitic nematode of rodents. Phyllocaulis variegatus, Phyllocaulis soleiformis and Phyllocaulis boraceiensis were experimentally infected to describe the kinetics of L3 elimination in the mucus secretions of those veronicelid species. A maximum of 2 L3/g/day was found in the mucus, while the number of L3 isolated from the fibromuscular tissues varied from 14 to 448. Productive infection was established by inoculations in the hyponotum or in the body cavity, through the tegument. Intra-cavity injection is a less complex procedure and permits a better control of inocula. A preliminary trial to titrate the infective dosis for P. variegatus indicated that inocula should range between 1000 and 5000 L1. The data also confirmed the importance of P. variegatus as an intermediate host of A. costaricensis.

Animais aquáticos de importância médica no Brasil

Os acidentes por animais aquáticos venenosos e traumatizantes podem provocar morbidez importante em humanos. Em 236 ocorrências por animais marinhos observadas pelo autor, os ouriços-do-mar causaram cerca de 50%, os cnidários (cubomedusas e caravelas) 25% e peixes venenosos (bagres, arraias e peixes-escorpião) 25% dos acidentes. Nos rios e lagos, as arraias, bagres e mandis causam acidentes que têm mecanismo do envenenamento e efeitos das toxinas semelhantes às espécies marinhas. Em uma série de cerca de 200 acidentes em pescadores de água doce, quase 40% foram causados por bagres e mandis, 5% por arraias de água doce e 55% por peixes traumatogênicos, como as piranhas e as traíras. O autor demonstra os principais animais aquáticos que causam acidentes no Brasil, apresenta aspectos clínicos dos envenenamentos e discute medidas terapêuticas para o controle da intensa sintomatologia observada principalmente nos acidentes causados por cnidários e peixes venenosos.

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.

Características de Vibrio parahaemolyticus isolados de mexilhões (Perna perna) comercializados em Niterói, Rio de Janeiro

O ecossistema marinho é o habitat natural de bactérias como Vibrio parahaemolyticus, um importante patógeno causador de gastrenterite humana associada ao consumo de alimentos marinhos. Na presente investigação, foi avaliada a presença de V. parahaemolyticus a partir de 86 amostras de mexilhões in natura e pré-cozidos. Vibrio parahaemolyticus foi isolado a partir de 11,6% dos mexilhões in natura e pré-cozidos avaliados. Todas as cepas avaliadas demonstraram-se urease positivas e 28,5% Kanagawa positivas sugerindo um potencial patogênico para o homem. Houve a predominância do sorotipo O10:K52 e a identificação da cepa emergente O3:K6. Esses resultados apontam para a relevância epidemiológica de V. parahaemolyticus em casos de gastrenterite humana após consumo de mexilhões sem cozimento adequado (100ºC/15min). Além disso, é importante alertar as autoridades de Vigilância Sanitária no Brasil quanto a sua presença na cadeia alimentar e seus riscos para a Saúde Pública.

Prurido do traje de banho: relato de seis casos no Sul do Brasil

O prurido do traje de banho ou seabather’s eruption é uma dermatite intensamente pruriginosa que ocorre pelo contato com larvas plânulas do cnidário cifozoário Linuche unguiculata, especialmente sob os trajes de banhistas. As larvas disparam seus nematocistos a partir de cnidócitos ou células urticantes de defesa na pele da vítima, causando uma típica erupção pápulo-eritemato-pruriginosa. Os primeiros cinco casos descritos no Brasil foram publicados em 2001, no litoral Sudeste (Ubatuba, SP), obtendo-se associação com larvas de Linuche unguiculata, uma vez que a ocorrência e o ciclo de vida do cnidário já haviam sido estudados no Canal de São Sebastião, SP. Os autores relatam os seis casos na região Sul do Brasil (Estado de Santa Catarina), enfatizando os aspectos clínicos e a pesquisa para identificação do agente na água do mar local.

Intestinal helminthes and/or Toxocara infection are unrelated to anti-HBs titers in seven-year-old children vaccinated at birth with recombinant hepatitis B vaccine

The aim of this investigation was to evaluate the possible effect of nematode infection on anti-HBs antibody levels in the serum of seven-year-old schoolchildren vaccinated at birth with the recombinant hepatitis B vaccine. Anti-HBs and anti HBc antibodies were evaluated in the sera of 100 schoolchildren with at least one intestinal nematode and/or a positive serological reaction for anti-Toxocara antibodies and in 95 schoolchildren without intestinal helminthiasis or serum anti-Toxocara antibodies. Both groups were from public elementary schools located on the urban periphery of Vitória, ES, Brazil. Among these 195 children, the median anti-HBs antibody titer was 31.3IU/ml and the frequency of titers less than 10IU/ml was 33.8% (95% CI: 27.1-40.4%). There were no significant differences between the medians of anti-HBs titers or the frequency of titers less than 10IU/ml between the groups with or without helminthes (29.5 and 32.9IU/ml and 33 and 34.7%, respectively; p>0.05). Even when the children with intestinal nematodes and/or anti-Toxocara antibodies and with blood eosinophil counts over 600/mm³ were compared with children without infection from intestinal nematodes and without anti-Toxocara antibodies, with blood eosinophil counts less than 400 eosinophils/mm³, these differences were not significant. None of the children presented anti-HBc antibodies. In conclusion, infections with intestinal nematodes and/or the presence of anti-Toxocara antibodies did not interfere with the anti-HBs antibody titers in seven-year-old children vaccinated at birth with the recombinant hepatitis B vaccine.