Parasitology Research

Probiotics have shown promising results as a potential method to control toxocariasis in mice inoculated with embryonated eggs of Toxocara canis. This study aimed to evaluate the protective effect of Saccharomyces boulardii in mice fed in natura chicken livers infected with T. canis. Twenty 15-day-old male Sussex chickens were inoculated with 300 T. canis embryonated eggs via intragastric catheter (GI). After 72 h of infection, each liver was collected and individually offered to a group of 20 mice. Mice that received supplemented ration with S. boulardii (1.107 colony forming units) and consumed in natura chicken liver showed reduction in infection intensity of 67.1%. This study demonstrated that administration of S. boulardii has potential as a probiotic to assist in controlling visceral toxocariasis caused by the consumption of viscera from paratenic hosts containing infective parasite larvae.

Sự xâm nhập của sinh vật là một mối đe dọa lớn đối với đa dạng sinh học và các hệ sinh thái trên toàn cầu và có thể góp phần vào sự phát triển của các bệnh truyền nhiễm mới nổi. Chúng tôi đã kiểm tra tỷ lệ mắc phải và sự đa dạng hệ phận của các ký sinh trùng haemosporidian ở các loài sẻ nhà (Passer domesticus) không bản địa và các loài sẻ đầu xám miền nam (Passer diffusus) bản địa. Mẫu máu từ 104 con sẻ (74 con sẻ nhà và 30 con sẻ đầu xám miền nam) được bắt bằng lưới ở bên trong và xung quanh Vườn quốc gia Kruger đã được sử dụng. DNA gen được chiết xuất từ mỗi mẫu máu và được thực hiện các phân tích PCR nested, giải trình tự Sanger và phân tích hệ phận. Tổng cộng, 35,57% (37/104) số chim được kiểm tra bị nhiễm ít nhất một ký sinh trùng haemosporidian. Các con sẻ đầu xám miền nam có tỷ lệ ký sinh trùng cao hơn (60%) so với sẻ nhà (24,3%). Tổng cộng có 16 dòng ký sinh trùng đã được xác định, trong đó có tám dòng mới. Trong khi Haemoproteus spp. cho thấy đa dạng dòng cao nhất, thì Leucocytozoon spp. lại là ký sinh trùng phổ biến nhất, mặc dù có sự khác biệt đáng kể giữa các loài sẻ. Một trường hợp nhiễm Plasmodium sp. được ghi nhận ở một con sẻ đầu xám miền nam. Hỗ trợ cho giả thuyết giải phóng kẻ thù, chúng tôi phát hiện rằng tỷ lệ nhiễm ở các con sẻ nhà không bản địa thấp hơn tỷ lệ ghi nhận ở vùng xuất xứ của chúng và cũng rằng chúng chỉ bị nhiễm bởi các dòng ký sinh trùng bản địa.

Echinococcosis is a worldwide neglected zoonotic disease. Alveolar echinococcosis (AE) poses a more serious threat to life and health than cystic echinococcosis, and has been one of the world’s most lethal chronic parasitosis. Assessment of metacestode activity status is essential for individual treatment strategy design for a given AE patient, and fluorodeoxyglucose positron-emission tomography (FDG-PET) has been the gold standard. In this study, we reviewed previous evidence on AE activity assessment using contrast-enhanced ultrasound (CEUS), and its comparison with FDG-PET. The results showed good consistency between them, indicating CEUS as a suitable substitute for FDG-PET. With its advantage as being readily portable, widely available, and not costly, CEUS is more suitable for use in the developing countries and rural areas.

Biting midges (Culicoides spp.) are vectors of bluetongue and Schmallenberg viruses. Treatment of mesh barriers is a common method for preventing insect-vectored diseases and has been proposed as a means of limiting Culicoides ingression into buildings or livestock transporters. Assessments using animals are costly, logistically difficult and subject to ethical approval. Therefore, initial screening of test repellents/insecticides was made by applying treatments to mesh (2 mm) cages surrounding Onderstepoort light traps. Five commercial treatments were applied to cages as per manufacturers’ application rates: control (water), bendiocarb, DEET/p-menthane-3,8-diol (PMD) repellent, Flygo (a terpenoid based repellent) and lambda-cyhalothrin. The experimental design was a 5 × 5 Latin square, replicated in time and repeated twice. Incongruously, the traps surrounded by DEET/PMD repellent-treated mesh caught three to four times more Obsoletus group Culicoides (the commonest midge group) than the other treatments. A proposed hypothesis is that Obsoletus group Culicoides are showing a dose response to DEET/PMD, being attracted at low concentrations and repelled at higher concentrations but that the strong light attraction from the Onderstepoort trap was sufficient to overcome close-range repellence. This study does not imply that DEET/PMD is an ineffective repellent for Culicoides midges in the presence of an animal but rather that caution should be applied to the interpretation of light trap bioassays.

In this study, rodents (Rattus rattus) and mollusks (Achatina fulica) were captured in a small forest located in a large metropolitan city in Brazil, and they were examined to investigate possible parasitism by Angiostrongylus cantonensis. The parasites were recovered as helminths from the pulmonary arteries of the synanthropic rodents and as third-stage larvae (with Metastrongylidae family characteristics) from the mollusks. To confirm the species, these larvae were used to experimentally infect Rattus norvegicus for the posterior recovery of adult helminths. To identify the adult helminths, morphological, morphometric, molecular, and phylogenetic techniques were employed. Furthermore, we also characterized the histological lesions associated with parasitism in naturally infected definitive hosts. Our results demonstrated the occurrence of a natural life cycle of A. cantonensis (with the presence of adult helminths) in definitive hosts, Rattus rattus, and third-stage larvae in an intermediate host, A. fulica. In free-living rodents, lesions of granulomatous pneumonia in the lungs and meningitis in the brain were also found. These results warn of the risk of accidental transmission of A. cantonensis to human residents around the park because of the extensive interaction among the fauna of the park, domestic animals, and the surrounding human population.

Belgian Landrace piglets were experimentally infected with eggs of aTaenia sp. of Korean origin. At autopsy, metacestodes were present only in the livers. The proportion of degenerated metacestodes increased from 12%–39% at 5 weeks to 94%–100% at 10 weeks after infection. A sandwich enzyme-linked immunosorbent assay (ELISA) using monoclonal antibodies raised against the excretory-secretory products ofT. saginata metacestodes detected circulating antigen in the sera of the pigs at 1 week post-infection. A good correlation was found between the presence of viable metacestodes and the detection of circulating antigen; the latter disappeared as the metacestodes died off. However, the antibodies were detected only after 3 weeks of infection and onwards until the necropsy of the pigs.

The need for an alternative methodology to assess disease activity in the case of malaria led us to evaluate the usefulness of studying the humoral immune response to establish the diagnosis of past or recent malaria. For this purpose, we analyzed sera from 439 individuals living in endemic areas of the Amazon region (Ariquemes, Rondonia). Individuals were classified according to the number and the date of past crises. The enzyme-linked immunosorbent assay (ELISA) was performed to evaluate the IgG/IgM ratio so as to discriminate acute or recent malaria from past infections against crude and defined (SPF70)Plasmodium falciparum asexual blood-stage antigens. We also analyzed the humoral immune response against components presented in crudeP. falciparum antigen by the immunoblot technique. Use of the IgG/IgM ratio values did not allow us to differentiate acute from past infections. However, when we analyzed the humoral immune response to parasite components, we were capable of identifying a polypeptide with a molecular weight ranging up to 40 kDa, which was recognized by all parasitized polyinfected individuals studied but not by individuals with negative thick blood smears. In view of these data, we conclude that the 40-kDa polypeptide may represent a powerful tool in the diagnosis of acute malaria, mainly for screening blood donors in endemic areas.

Acidic mucins such as sialomucin and sulfomucin produced by intestinal epithelial cells have been implicated in the protection of the mucosa from pathogens. In the present study, we analyzed the alteration of acidic mucins in the jejunum of euthymic and athymic rats infected with the nematode Nippostrongylus brasiliensis using alcian blue staining and a high iron-diamine method. The numbers of sialomucin+ goblet cells increased markedly 7 and 10 days post-infection and decreased gradually thereafter in euthymic rats, while athymic rats did not show sialomucin+ goblet cell hyperplasia at least until 28 days post-infection, suggesting that sialomucin production might be regulated by thymus-derived T cells. On the other hand, the numbers of sulfomucin+ goblet cells increased markedly 28 days post-infection in both euthymic and athymic rats despite the fact that sulfomucin+ goblet cell numbers in uninfected athymic rats were significantly smaller than in euthymic rats. Real-time polymerase chain reaction studies on the gene transcription levels of O-glycan sulfotransferases Gal3ST1, Gal3ST2, Gal3ST3, and Gal3ST4 in the jejunal epithelium increased gradually toward day 28 post-infection in euthymic and athymic rats. These results suggest that the production of sulfomucin and expression of Gal3STs are inducible by nematode infection without the activation of thymus-derived T cells.

Adult Toxocara canis and Ascaris suum were incubated in vitro in media containing 0.1, 1, 10 or 100 µg/ml flubendazole in order to study drug-derived effects. This incubation was done for 8 h and repeated (in some groups) after 24 h for another 8 h. The onset and intensity of flubendazole-derived effects were dosage-dependent and time-dependent, i.e. the same grade of damage was reached when incubating for a longer period at a low dosage or for a shorter period in medium containing a high amount (10 or 100 µg/ml) of flubendazole. A repeated incubation in drug-containing medium was superior to a single exposure. Flubendazole is apparently able to penetrate into the worm's interior via the cuticle. This became evident in worms with sealed orifices, which showed identical damage to worms which were not sealed. The type of tissue damage due to flubendazole was identical in both worm species when exposed to any of the drug dosages used. The principal mode of action of flubendazole was based on the complete reduction of microtubuli-polymerisation inside the parasite's cells. This apparently led to the complete destruction of the hypodermis, muscle layer and intestine. Flubendazole also stopped the formation of gametes. Summarising, even low concentrations of flubendazole (0.1 µg/ml) led to significant and irreversible damage in all worms studied.