Wild Rodents as Experimental Intermediate Hosts of Lagochilascaris minor Leiper, 1909

A total of 25 specimens of Cavia porcellus (guinea pig), 5 Dasyprocta agouti (agouti), and 22 Calomys callosus (vesper mice) were inoculated with infective eggs of Lagochilascaris minor. The inoculum was prepared with embryonated eggs and orally administered to each individual animal through an esophagus probe. In parallel, 100 specimens of Felis catus domesticus were individually fed with 55-70 nodules containing 3rd-stage larvae encysted in tissues of infected rodents. Animals were examined and necropsied at different time intervals. The migration and encystment of L3 larva was observed in viscera, skeletal muscle, adipose and subcutaneous tissues from all rodents. Adult worms localized at abscesses in the cervical region, rhino, and oropharynx were recovered from domestic cats inoculated with infected rodent tissues. Through this study we can conclude that: (1) wild rodents act as intermediate hosts, characterizing this ascarid heteroxenic cycle; (2) in natural conditions rodents could possibly act as either intermediate hosts or paratenic hosts of Lagochilascaris minor; (3) despite the occurrence of an auto-infecting cycle, in prime-infection of felines (definite hosts) the cycle is only completed when intermediate hosts are provided; and (4) in the wild, rodents could serve as a source of infection for humans as they are frequently used as food in regions with the highest incidence of human lagochilascariasis.

Survey of canine heartworm in the city of Recife, Pernambuco, Brazil

Six hundred and eleven random-source dogs (338 male, 273 female) one year of age or older, from six sections of the city of Recife, Pernambuco, were examined antemortem for circulating microfilariae Dirofilaria immitis and Dipetalonema reconditum adult heartworm (D. immitis) antigen, and examined postmortem for adult heartworms. The prevalence of heartworm infection was 2.3% (14/611), as determined by necropsy for adult worms, and 1% (6/611) had circulating microfilariae of D. immitis; thus, 57.1% of the heartworm-infected dogs had occult infections. The results of serological testing indicated that 1.3% (8/611) of the dogs were positive for adult heartworm antigen. A total of 42 (6.9%) of the dogs had microfilariae of D. reconditum; 40 of these had only D. reconditum and two additional dogs had microfilariae of both species, D. immitis and D. reconditum.

Evaluation of detection methods for Virus, Viroids and Phytoplasmas affecting pear and apple

The RT-PCR technique for the detection of apple stem grooving virus (ASGV), apple stem pitting virus (ASPV), apple chlorotic leaf spot virus (ACLSV), apple mosaic virus (ApMV) and pear blister canker viroid (PBCV) was evaluated for health control of fruit plants from nurseries. The technique was evaluated in purified RNA and crude extracts and also in phloem collected in autumn and from young spring shoots. The results obtained for phytoplasma detection with ribosomal and non-ribosomal primers are also presented.

The importance of root-produced volatiles as foraging cues for entomopathogenic nematodes

Background Entomopathogenic nematodes (EPNs) are tiny parasitic worms that parasitize insects, in which they reproduce. Their foraging behavior has been subject to numerous studies, most of which have proposed that, at short distances, EPNs use chemicals that are emitted directly from the host as host location cues. Carbon dioxide (CO2) in particular has been implicated as an important cue. Recent evidence shows that at longer distances several EPNs take advantage of volatiles that are specifically emitted by roots in response to insect attack. Studies that have revealed these plant-mediated interactions among three trophic levels have been met with some disbelief. Scope This review aims to take away this skepticism by summarizing the evidence for a role of root volatiles as foraging cues for EPNs. To reinforce our argument, we conducted olfactometer assays in which we directly compared the attraction of an EPN species to CO2 and two typical inducible root volatiles. Conclusions The combination of the ubiquitous gas and a more specific root volatile was found to be considerably more attractive than one of the two alone. Hence, future studies on EPN foraging behavior should take into account that CO2 and plant volatiles may work in synergy as attractants for EPNs. Recent research efforts also reveal prospects of exploiting plant-produced signals to improve the biological control of insect pests in the rhizosphere.

Study of Schistosoma mansoni isolates from patients with failure of treatment with oxamniquine

After three successive treatments with oxamniquine the continuing elimination of Schistosoma mansoni eggs was observed in patients, who came from various regions of Brazil, with different clinical forms of schistosomiasis. The objective of the present study was to determine the experimental behaviour of five different S. mansoni isolates in Swiss Webster mice that were submitted to treatment with the same drug. The experimental group with failure of treatment showed higher mean number of surviving male worms when it was compared to the group without failure of treatment. These date suggest the possibility of resistance to oxamniquine.

Vectorial competence of Aedes aegypti (Linnaeus 1762) Rio de Janeiro Strain, to Dirofilaria immitis (Leidy 1856)

Dirofilaria immitis (Leidy 1856), a nematode parasite, is the etiologic agent of canine heartworm disease and mosquitoes are essential intermediate hosts. Mosquito susceptibility to the worms differ with species, strains and also among individuals of the same strain. To evaluate the degree of susceptibility of Rio de Janeiro laboratory raised strain of Aedes aegypti, we fed mosquitoes on canine blood with different densities of microfilariae (mf). There was no significant difference in the rate of development among the three different densities of mf. Infective larvae were found in the head and proboscis of all mosquitoes provided bloodmeals with different densities of mf after the 11th day post-infection. The infection rate of mosquitoes after ingestion of blood containing 3,000 mf/ml, 5,000 mf/ml and 7,000 mf/ml were 55.3%, 66.7% and 100%, respectively. The vector efficiency indices ranged from 1.6 to 9.3. The finding of L3 stage larvae, high infection rates and vector efficiency indices suggest that Ae. aegypti, Rio de Janeiro laboratory strain, is a potential vector of D. immitis, although of low efficiency.

Preliminary analysis of Sm14 in distinct fractions of Schistosoma mansoni adult worm extract

In previous studies it was shown that the recombinant molecule, r-Sm14, induces high levels of protection against Schistosoma mansoni infection in two outbred animal models and immune crossprotection against infection by Fasciola hepatica in Swiss outbred mice. r-Sm14 was derived from a living worm extract, called SE, and is being developed as the molecular basis of an anti-helminth bivalent vaccine against the two parasites, for medical and veterinary application. Present data refer to SDS-PAGE and Western Blotting analysis of four different preparations of S. mansoni adult worms focusing Sm14 identification. The extracts correspond to the initial fraction of the SE extraction process, containing products released by living worms (SEi); SE2, reextraction of adult worms in PBS; and SE of separated male and female adult worms. In all extracts it was possible to detect the component of 14 kDa, that was recognized by specific anti-rSm14 antibody raised in rabbits.

The impact of repeated treatment with praziquantel of schistosomiasis in children under six years of age living in an endemic area for Schistosoma haematobium infection

Praziquantel was given every eight weeks for two years to children aged under six years of age, living in a Schistosoma haematobium endemic area. Infection with S. haematobium and haematuria were examined in urine and antibody profiles (IgA, IgE, IgM, IgG1, IgG2, IgG3, and IgG4) against S. haematobium adult worm and egg antigens were determined from sera collected before each treatment. Chemotherapy reduced infection prevalence and mean intensity from 51.8% and 110 eggs per 10 ml urine, respectively, before starting re-treatment programme to very low levels thereafter. Praziquantel is not accumulated after periodic administration in children. Immunoglobulin levels change during the course of treatment with a shift towards 'protective' mechanisms. The significant changes noted in some individuals were the drop in 'blocking' IgG2 and IgG4 whereas the 'protecting' IgA and IgG1 levels increased. The antibody profiles in the rest of the children remained generally unchanged throughout the study and no haematuria was observed after the second treatment. The removal of worms before production of large number of eggs, prevented the children from developing morbidity.

Some Morphological Aspects of Cylicocyclus brevicapsulatus (Nematoda: Cyathostominae) Parasite of Horse

This paper describes some morphological aspects of Cylicocyclus brevicapsulatus (Ihle, 1920) (Nematoda: Cyathostominae) from Equus caballus in Brazil. The worms were studied using an optical microscope (measurements and illustrations) and a scanning electron microscope for a more detailed examination of the external morphology. The buccal capsule is very short, with a very thin wall, and the dorsal gutter is absent. Other morphological aspects are described including measurement of the spicules and gubernaculum.

Nematode Infections Are Risk Factors for Staphylococcal Infection in Children

Nematode infection may be a risk factor for pyogenic liver abscess in children and we hypothesized that the immunomodulation induced by those parasites would be a risk factor for any staphylococcal infection in children. The present study was designed to compare, within the same hospital, the frequency of intestinal nematodes and Toxocara infection in children with and without staphylococcal infections. From October 1997 to February 1998, 80 children with staphylococcal infection and 110 children with other diseases were submitted to fecal examination, serology for Toxocara sp., evaluation of plasma immunoglobulin levels, and eosinophil counts. Mean age, gender distribution, birthplace, and socioeconomic conditions did not differ significantly between the two groups. Frequency of intestinal nematodes and positive serology for Toxocara, were remarkably higher in children with staphylococcal infections than in the non-staphylococcal group. There was a significant correlation between intestinal nematodes or Toxocara infection and staphylococcal infection in children, reinforced by higher eosinophil counts and higher IgE levels in these children than in the control group. One possible explanation for this association would be the enhancement of bacterial infection by the immunomodulation induced by helminth infections, due to strong activation of the Th2 subset of lymphocytes by antigens from larvae and adult worms.

Ultrastructural alterations in adult Schistosoma mansoni caused by artemether

Progress has been made over the last decade with the development and clinical use of artemether as an agent against major human schistosome parasites. The tegument has been identified as a key target of artemether, implying detailed studies on ultrastructural damage induced by this compound. We performed a temporal examination, employing a transmission electron microscope to assess the pattern and extent of ultrastructural alterations in adult Schistosoma mansoni harboured in mice treated with a single dose of 400 mg/kg artemether. Eight hours post-treatment, damage to the tegument and subtegumental structures was seen. Tegumental alterations reached a peak 3 days after treatment and were characterized by swelling, fusion of distal cytoplasma, focal lysis of the tegumental matrix and vacuolisation. Tubercles and sensory organelles frequently degenerated or collapsed. Typical features of subtegumental alterations, including muscle fibres, syncytium and parenchyma tissues, were focal or extensive lysis, vacuolisation and degeneration of mitochondria. Severe alterations were also observed in gut epithelial cells and vitelline cells of female worms. Our findings of artemether-induced ultrastructural alterations in adult S. mansoni confirm previous results obtained with juvenile S. mansoni and S. japonicum of different ages.

Partial molecular characterization of Sm8, a tegumental antigen of Schistosoma mansoni

Sm8 is a major tegumental antigen of Schistosoma mansoni. The partial cDNA was isolated and analyzed. Sequence analysis revealed transmembrane compatible hydrophobic domains and a putative leucine zipper pattern. The mRNA and the protein are predominantly expressed in adult worms.

Nodular typhlitis associated with the nematodes Heterakis gallinarum and Heterakis isolonche in pheasants: frequency and pathology with evidence of neoplasia

An investigation related to the frequency and pathology of Heterakis gallinarum and pathology of Heterakis isolonche in pheasants from Rio de Janeiro, Brazil was conducted by means of clinical examinations, necropsies, and histopathological analysis in 50 ring-necked pheasants from backyard flocks of 11 localities; also, histological sections of caeca of golden pheasants deposited in the Helminthological Collection of the Oswaldo Cruz Institute (CHIOC) have been considered in the present study. During necropsies, only specimens of H. gallinarum were recovered with a prevalence of 90%, mean intensity of 81.9 and range of infection of 1-413. Gross lesions were characterized by congestion, thickening, petechial haemorrhages of the mucosa, intussusception, and nodules in the cecal wall. Under microscopy, chronic difuse typhlitis, haemosiderosis, granulomas with necrotic center in the submucosa and leiomyomas in the submucosa, muscular and serosa associated with immature H. gallinarum worms were observed. The examination of histological sections previously deposited in the CHIOC, revealed more severe alterations associated with concomitant infections with H. gallinarum and H. isolonche in golden pheasants, and were characterized by several necrotic areas with cholesterol clefts in the submucosa, giant cell granulomas in the submucosa, and serosa centralized by necrosis and worm sections and neoplastic nodules in the muscular and submucosa.

The fossil tabanids (Diptera Tabanidae): when they began to appreciate warm blood and when they began transmit diseases?

A discussion of the known fossil tabanids (Diptera Tabanidae) is presented based on fossil evidence. This includes the origin of the hemathophagy in the Brachycera, more specifically for tabanids. Several tabanid species in the extant fauna are vectors for disease-producing organisms that affect humans and animals. Bacteria, viruses, rickettsiae, protozoa, and filarial worms can be transmitted by them, causing such diseases as anthrax, tularemia, anaplasmosis, various forms of trypanosomiasis, Q fever, and filariasis. However, if tabanids are directly responsible for all of these diseases is not consensual and the known fossil evidence is presented here.

Evolution of ascariasis in humans and pigs: a multi-disciplinary approach

The nematode parasite Ascaris lumbricoides infects the digestive tracts of over 1.4 billion people worldwide, and its sister species, Ascaris suum, has infected a countless number of domesticated and feral pigs. It is generally thought that the putative ancestor to these worms infected either humans or pigs, but with the advent of domestication, they had ample opportunity to jump to a new host and subsequently specialize and evolve into a new species. While nuclear DNA markers decisively separate the two populations, mitochondrial sequences reveal that three major haplotypes are found in A. suum and in A. lumbricoides, indicating either occasional hybridization, causing introgression of gene trees, or retention of polymorphism dating back to the original ancestral species. This article provides an illustration of the combined contribution of parasitology, archaeoparasitology, genetics and paleogenetics to the history of ascariasis. We specifically investigate the molecular history of ascariasis in humans by sequencing DNA from the eggs of Ascaris found among ancient archeological remains. The findings of this paleogenetic survey will explain whether the three mitochondrial haplotypes result from recent hybridization and introgression, due to intensive human-pig interaction, or whether their co-occurrence predates pig husbandry, perhaps dating back to the common ancestor. We hope to show how human-pig interaction has shaped the recent evolutionary history of this disease, perhaps revealing the identity of the ancestral host.