Infectious diseases in paediatric pathology: experience from a developing country

Infectious and parasitic diseases have always challenged man. Although many of them are typically seen in some areas of the world and can be adequately managed by just improving socioeconomic status and sanitary conditions, they are still quite prevalent and may sometimes be seen outside their original geographical areas. Human migration due to different reasons, tourism, blood transfusion and solid organ transplantation has created new concerns for health professionals all over the world. If not for diagnostic purposes, at least these tropical and infectious diseases should be largely known because their epidemiology, pathogenesis, host/parasite interaction, inflammatory and reparative responses are quite interesting and teach us about human biology. Curiosity is inherent to pathology practice and so we are compelled to look for things other than tumours or degenerative diseases. This review focuses on infectious and parasitic diseases found in a developing country and brings up-to-date information on diseases caused by viruses (dengue, yellow fever), bacteria (typhoid fever, leprosy), parasites (Chagas` disease, cutaneous and visceral leishmaniasis, amoebiasis, Capillaria hepatica, schistosomiasis, cysticercosis) and caused by fungi (paracoccidioidomycosis, cryptococcosis, histoplasmosis) that may be useful for pathologists when facing somewhat strange cases from developing countries.

In vitro schistosomicidal effects of some phloroglucinol derivatives from Dryopteris species against Schistosoma mansoni adult worms

The rhizomes of Dryopteris species have popularly been used as vermifuge in flatworm infections. The aim of this work was to evaluate the in vitro schistosomicidal activity of some phloroglucinol compounds, obtained from the rhizomes of Dryopteris species, against Schistosoma mansoni adult worms. All worm pairs were dead after 24 h of incubation with aspidin 25 to 100 mu M (1), flavaspidic acid 50 and 100 mu M (2), methylene-bis-aspidinol 100 mu M (3), and desaspidin 25 to 100 mu M (4). Worms incubated with 1 (25 to 100 mu M) and 2 (50 to 100 mu M) showed decrease motor activity with tegumental alterations, while 3 (100 mu M) and 4 (10 to 100 mu M) showed decrease motor activity without tegumental alterations. Desaspidinol (5) and filicinic acid (6), at the tested concentrations (10 to 100 mu M), did not show activity against adult worms of S. mansoni. Praziquantel (10 mu M), used as positive control, caused death of the parasites and tegumental alterations without separation of worms. In the groups treated with 100 A mu M of compounds 1-4, the viability of the adult worms was similar to the positive control group, in which the worms were dead. Also, both the egg productions and the development of eggs produced by the adult worms were inhibited by the incubation with compounds 1-4 (10 and 100 mu M) in comparison with the negative control (RPMI 1640 medium). It is suggested that the in vitro schistosomicidal effects of phloroglucinols derivatives 1, 2, 3, and 4 may be related to the inhibition of oxidative phosphorylation pathway in S. mansoni. The present results confirmed the traditional indications of rhizomes from Dryopteris species, which possess phloroglucinol compounds, in the treatment of tapeworm infections.

The ubiquitin-proteasome system in Strongyloididae. Biochemical evidence for developmentally regulated proteolysis in Strongyloides venezuelensis

Nematode parasites from the genus Strongyloides spp. are important pathogens of the intestinal mucosa of animals and humans. Their complex life cycles involve alternating developmental adaptations between larvae stages and the adult parthenogenetic female. Here, we report, primarily through homology-based searching, the existence of the major components of the ubiquitin-proteasome system in this genus, using the available EST data from S. ratti, S. stercoralis, and Parastrongyloides trichosuri. In this study, S. venezuelensis was used as our model organism for detection of proteasome activity and ubiquitinated substrates in cytosolic preparations from the L3 larvae and the adult female. Marked differences in proteasome capabilities were found when these two stages were compared. A preference for degradation of chymotryptic synthetic peptides was found in both stages with the adult exhibiting a higher rate of hydrolysis compared to the larvae. Due to the high evolutionary conservation of proteasome alpha subunits, an anti-human proteasome antibody was able to recognize proteasome subunits in these preparations by Western blotting, supporting the proposal that the activity of the ubiqutin-proteasome system is developmentally regulated in this nematode.

Immunolocalization and pathological alterations following Strongyloides venezuelensis infection in the lungs and the intestine of MHC class I or II deficient mice

The present study, investigated the mechanisms involved in the immune responses of Major Histocompatibility Complex class I or class II knockout mice, following Strongyloides venezuelensis infection. Wild-type C57BL/6 (WT), MHC II(-/-) and MHC I(-/-) mice were individually inoculated with 3000 larvae (U) of S. venezuelensis and sacrificed on days 1, 3, 5, 8, 13 and 21 post-infection (p.i.). Samples of blood, lungs and small intestines were collected. The tissue samples were stained with hematoxylineosin for the pathological analysis. The presence of the parasite was demonstrated by immunoperoxidase analysis. MHC II(-/-) mice presented a significantly higher number of adult worms recovered from the small intestine on day 5 p.i. and presented elevated numbers of eggs in the feces. The infection by S. venezuelensis was completely eliminated 13 days after infection in WT as well as in MHC I(-/-) mice. In MHC II(-/-) mice, eggs and adult worms were still found on day 21 p.i., however, there was a significant reduction in their numbers. In the lung, the parasite was observed in MHC I(-/-) on day 1 p.i. and in MHC II(-/-) mice on days 1 and 5 p.i. In the small intestine of WT mice, a larger number of parasites were observed on day 8 p.i. and their absence was observed after day 13 p.i. Through immunohistochemistry analysis, the parasite was detected in the duodenum of WT on days 5 and 8 p.i., and in knockout mice on days 5, 8 and 13 p.i.; as well as in posterior portions of the small intestine in MHC I(-/-) and MHC II(-/-) on day 13 p.i., a finding which was not observed in WT mice. We concluded that immunohistochemistry analysis contributed to a more adequate understanding of the parasite localization in immunodeficient hosts and that the findings aid in the interpretation of immunopathogenesis in Strongyloides infection. (C) 2008 Elsevier B.V. All rights reserved.

Reappraisal of the immunopathogenesis of disseminated leishmaniasis: in situ and systemic immune response

Disseminated leishmaniasis (DL) is an emerging form of Leishmania braziliensis infection characterised by multiple cutaneous lesions on different parts of the body and a high rate of mucosal involvement. Systemic production of TNF alpha and IFN-gamma in DL patients is lower than in cutaneous leishmaniasis (CL) caused by L braziliensis, which may account for parasite dissemination due to the decreased ability to control parasite growth. In this study, the systemic and in situ immune response of DL and CL patients was characterised through evaluation of chemokine and cytokine production. In situ evaluation showed similar production of IFN gamma, TNF alpha, IL-10, transforming growth factor-beta (TGF beta), chemokine (C-C motif) ligand 2 (CCL2), CCL3, CCL11 and chemokine (C-X-C motif) ligand 10 (CXCL10) in papular and ulcerative lesions from DL as well as in ulcerated lesions from CL. Serum levels of CXCL9, a chemokine that attracts 1-cells, was higher in serum from DL than from CL These data indicate that a decrease in the type 1 immune response in peripheral blood of DL patients is due to attraction of Leishmania antigen-activated T-cells to the multiple cutaneous lesions. This may account for the absence of or few parasites in the lesions and for the development of ulcers similar to those observed in CL (C) 2011 Royal Society of Tropical Medicine and Hygiene. Published by Elsevier Ltd. All rights reserved.

Cross-reactive IgE antibody responses to tropomyosins from Ascaris lumbricoides and cockroach

Background: Evidence indicates that infection with Ascaris lumbricoides may promote development of allergy and asthma. Objective: To study the role of tropomyosin, a pan-allergen in invertebrates, in IgE responses to A lumbricoides. Methods: Recombinant A lumbricoides and Periplaneta americana tropomyosins were expressed in Pichia pastoris. Levels of IgE to tropomyosins from A lumbricoides and P americana were determined by chimeric ELISA in sera from 119 children living in a parasite-endemic area and 112 patients with cockroach allergy from the allergy clinics. Presence of tropomyosin in A lumbricoides larvae at L3 stage was evaluated by immunofluorescence using mAb IA6, directed against mite tropomyosin. Molecular modeling of P americana and A lumbricoides tropomyosins was performed by using the MODELLER program. Results: A lumbricoides tropomyosin showed 69% to 98% sequence identity to tropomyosins from other invertebrates. The predicted structure of A lumbricoides tropomyosin was similar to that of P americana tropomyosin and showed the characteristic coiled-coil structure. Strong correlation was found for IgE antibodies to tropomyosins from A lumbricoides and P americana in sera from children living in a parasite-endemic area and from patients with cockroach allergy. Larvae of A lumbricoides reacted strongly with mAb IA6. Conclusion: Tropomyosin induces IgE responses in A lumbricoides-infected children and in patients allergic to cockroach.

Measurement of IgE antibodies to shrimp tropomyosin is superior to skin prick testing with commercial extract and measurement of IgE to shrimp for predicting clinically relevant allergic reactions after shrimp ingestion

Background: Shrimp is a frequent cause of food allergy. Tropomyosin is the major allergen in shrimp, and it shares homology to tropomyosins from other crustaceans, dust mites, cockroach, and parasites. Objective: The aim of this study was to determine the value of detection of IgE to shrimp tropomyosin in the diagnosis of shrimp allergy. Methods: We have studied 35 patients with asthma, rhinitis, or both who were sensitized to Dermatophagoides pteronyssinus. All subjects underwent skin prick testing in addition to double-blind, placebo-controlled food challenges (DBPCFC); oral open challenges; or both with shrimp. Measurements of IgE to shrimp and shrimp tropomyosin were carried out by means of CAP and chimeric ELISA, respectively. Results: Oral challenges confirmed the diagnosis of shrimp allergy in 7 patients. IgE measurement to shrimp tropomyosin was positive in 71.4% of the patients with shrimp allergy. Of the 28 patients without shrimp allergy, only 7.1% (2/28) had IgE to shrimp tropomyosin compared with 25% (7/28) who had IgE to shrimp and 35.7% (10/28) who had positive skin prick test responses to shrimp. Sensitivity was similar for all 3 methods (71.4%); in contrast, specificity of IgE to shrimp tropomyosin (92.8%) was greater than that of IgE to shrimp (75%) and skin prick testing (64.2%). With regard to diagnostic efficiency, measurement of IgE to shrimp tropomyosin was superior to measurement of IgE to shrimp and skin prick testing (88.5%, 74.2%, and 65.7%, respectively). Conclusion: Use of measurements of IgE to shrimp tropomyosin provided added value to the diagnosis of shrimp allergy. (J Allergy Clin Immunol 2010;125:872-8.)

Bursts of transposition from non-long terminal repeat retrotransposon families of the RTE clade in Schistosoma mansoni

The genus Schistosoma is composed of blood flukes that infect vertebrates, from which three species are major causative agents of human schistosomiasis, a tropical disease that affects more than 200 million people. Current models of the recent evolution of Schistosoma indicate multiple events of migration and speciation from an Asian ancestral species. Transposable elements are important drivers of genome evolution and have been hypothesised to have an important role in speciation. In this work, we describe a comprehensive inventory of Schistosoma mansoni and Schistosoma japonicum retrotransposons, based on their recently published genomic data. We find a considerable difference in retrotransposon representation between the two species (22% and 13%, respectively). A large part of this difference can be attributed to higher representation of two previously described families of S. mansoni retrotransposons (SR2 and Perere-3/SR3), compared with the representation of their closest relative families in S. japonicum. A more detailed analysis suggests that these two S. mansoni families were the subject of recent bursts of transposition that were not paralleled by their S. japonicum counterparts. We hypothesise that these bursts could be a consequence of the evolutionary pressure resulting from migration of Schistosoma from Asia to Africa and their establishment in this new environment, helping both speciation and adaptation. (C) 2009 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.

The involvement of CD4(+)CD25(+) T cells in the acute phase of Trypanosoma cruzi infection

The infection with Trypanosoma cruzi leads to a vigorous and apparently uncontrolled inflammatory response in the heart. Although the parasites trigger specific immune response, the infection is not completely cleared out, a phenomenon that in other parasitic infections has been attributed to CD4(+)CD25(+) T cells (Tregs). Then, we examined the role of natural Tregs and its signaling through CD25 and GITR in the resistance against infection with T. cruzi. Mice were treated with mAb against CD25 and GITR and the parasitemia, mortality and heart pathology analyzed. First, we demonstrated that CD4(+)CD25(+)GITR(+)Foxp3(+) T cells migrate to the heart of infected mice. The treatment with anti-CD25 or anti-GITR resulted in increased mortality of these infected animals. Moreover, the treatment with anti-GITR enhanced the myocarditis, with increased migration of CD4(+), CD8(+), and CCR5(+) leukocytes, TNF-alpha production, and tissue parasitism, although it did not change the systemic nitric oxide synthesis. These data showed a limited role for CD25 signaling in controlling the inflammatory response during this protozoan infection. Also, the data suggested that signaling through GITR is determinant to control of the heart inflammation, parasite replication, and host resistance against the infection. (C) 2008 Elsevier Masson SAS. All rights reserved.

Prevalence of Toxoplasma gondii and Neospora caninum infections in sheep from Federal District, central region of Brazil

Serum samples from 1028 sheep were collected from 32 herds within Federal District, in the central region of Brazil. The samples were examined by indirect fluorescent antibody test (IFAT) using sera diluted 1:64 and 1:50 as cut-off values for the detection of antibodies against Toxoplasma gondii and Neospora caninum, respectively. The observed prevalence for T. gondii infection was 38.22% (26.81%< CI 0.95 < 49.62%), and the titers ranged from 64 to 65536. The observed prevalence for N. caninum infection was 8.81% (7.08%< CI 0.95 < 10.53%). The titers ranged from 50 to 51200. The reactant sera to both pathogens corresponded to 4.67% of the samples. The risk factors were not determined because of the absence of negative herds for T. gondii and the high proportion of positive herds for N. caninum (87.50%). The prevalence for T. gondii infection was significantly higher among males than in females. The present work is the first report on seroprevalence of T. gondii and N. caninum in sheep from Federal District and shows that infection by both parasites is widespread in the ovine population from this region.

Differential diagnosis of oocysts of Hammondia-like organisms of dogs and cats by PCR-RFLP analysis of 70-kilodalton heat shock protein (HSP70) gene

Organisms of the genera Toxoplasma, Hammondia and Neospora, the Hammondia-like organisms, are closely related coccidian with similarly sized oocysts. Therefore, a diagnosis based on microscopy of oocysts in feces is not a method of choice for species identification of these important parasites. In this paper, we present a polymerase chain reaction coupled with restriction fragment length polymorphism (PCR-RFLP) method to differentially diagnose oocysts of Toxoplasma gondii from oocyst of Hammondia hammondi. Another PCR-RFLP was designed to differentiate oocysts of Hammondia heydorni from oocysts of Neospora spp. Both PCR-RFLP are based on nucleotide sequences of the Hsp70 coding gene. In conclusion, we presented two alternative molecular diagnostic assays that can be successfully applied for the differentiation of oocysts of Hammondia-like organisms shed by felids and canids.

Carios mimon (Acari: Argasidae): description of adults and redescription of larva

Carios mimon is an argasid tick common on Chiroptera, originally described from larvae collected on bats Mimon crenulatum from Bolivia and Eptesicus brasiliensis from Uruguay. Later it was also registered from Argentina and recently included among the Brazilian tick fauna. In Brazil, this species is very aggressive to man, resulting in intense inflammatory response and pain. It is known only by the larval description and its morphology resembles that from other species currently included into the genus Carios, formerly classified into the subgenus Alectorobius, genus Ornithodoros. Here we describe adults and redescribe the larva of C. mimon, based on light and scanning electron microscopy. Remarks about its morphological similarity with other species of this genus are also discussed. Molecular analysis inferred from a portion of the 16S rRNA mitochondrial gene placed C. mimon in a cluster supported by maximal bootstrap value (100%) with other argasid species (mostly bat parasites in the New World), which have been classified into either the genus Ornithodoros or Carios, depending on the Argasidae classification adopted by different authors.

Tick toxicosis in a dog bitten by Ornithodoros brasiliensis

Ticks are hematophagous parasites of people and animals and are a public health hazard in several countries. They are vectors of infectious diseases; in addition, the bite of some ticks, mainly from the Ornithodoros genus, may lead to local lesions and systemic illness, referred to as tick toxicosis. In this report, we describe a dog bitten by Ornithodoros brasiliensis, popularly known as the mouro tick. The main clinical findings were disseminated skin rash, pruritus, mucosal hyperemia, lethargy, and fever. Laboratory abnormalities 48 hours after the bites occurred included mild nonregenerative anemia, eosinophilia, basophilia, increased serum creatine kinase activity, increased serum C-reactive protein concentration, and prolonged coagulation times. Tick-borne pathogens were not detected by PCR analysis or serologic testing, supporting the diagnosis of a noninfectious syndrome due to tick bite, compatible with tick toxicosis.

Occurrence of antibodies anti-Neospora caninum, anti-Toxoplasma gondii, and anti-Leishmania chagasi in serum of dogs from Para State, Amazon, Brazil

A cross-sectional study was conducted to determine the occurrence of anti-Toxoplasma gondii, anti-Neospora caninum, and anti- Leishmania chagasi antibodies in dogs of the state of Para, Brazil. For this purpose, 129 blood samples were collected from dogs of different ages and gender. Samples of 72 dogs were collected from 39 rural properties from 19 municipalities, and 57 samples were from stray dogs, collected after captivity by the Center of Zoonosis Control from the municipality of Santar,m. The sera were analyzed for anti-T. gondii and anti-N. caninum antibodies by indirect fluorescent antibody tests with cutoff values of 1:16 and 1:50, respectively. For the presence of L. chagasi antibodies, enzyme-linked immunosorbent assay was used and positive results were confirmed by immunochromatographic method using the recombinant antigen K39. Of the total of 129 dogs, 90 (69.8%) were positive for T. gondii, 16 (12.4%) for N. caninum, and 30 (23.3%) for L. chagasi. Antibodies for all three parasites were found simultaneously in seven dogs (5.4%), mostly in urban dogs (six of seven). No association was observed related to gender and location (urban or rural) of dogs and occurrence of N. caninum and T. gondii antibodies although, regarding L. chagasi, higher prevalence was found in females (P < 0.02) and in dogs from urban location (P < 0.001). From the 39 farms, in 30 (76.9%) at least one dog was positive for T. gondii or N. caninum or both. Higher occurrence of Leishmania antibodies was observed in N. caninum-negative dogs (P < 0.05).

Experimental infection with Rangelia vitalii in dogs: Acute phase, parasitemia, biological cycle, clinical-pathological aspects and treatment

Recently we conducted the molecular characterization of Rangelia vitalii, a protozoan with high pathogenicity for young dogs in southern Brazil. To date, the descriptions of the disease have been restricted to natural infection cases. Therefore, this study aimed to evaluate the parasitemia, biological cycles and clinical-pathological findings in dogs experimentally infected with R. vitalii in the acute phase of disease, and also aimed to test a therapeutic protocol based on the diminazene aceturate. For this study, we used 12 young dogs (females), separated into two groups. Group A was composed of healthy dogs, not-infected (n = 5), and Group B consisted of animals infected with R. vitalii (n = 7). After infection, the animals were monitored by blood smear examinations, which showed intra-erythrocytic forms of the parasite 5 days post-infection (PI). Parasitemia increased progressively in these animals and had the highest peak of circulating parasites between 9 and 11 days PI. Subsequently, the parasitemia reduced and the protozoan was seen inside the leukocytes in days 17, 19 and 21 PI. The most prominent clinical signs observed at the 20 day PI of experiment were lethargy, fever and anorexia. We observed a decrease of hematocrit of infected animals compared with not-infected dogs, featuring a moderate anemia. Pathological evaluation of one dog in Group B at day 21 PI revealed splenomegaly, hepatomegaly, lymphadenopathy, and hemorrhages at necropsy. Histological examination showed only follicular hyperplasia in the spleen and lymph nodes, and the etiologic agent in the vascular endothelium. At 21 days PI, it was performed the treatment of dogs in Group B (n = 6) with a single dose of diminazene aceturate, which showed a curative efficacy of 100% in cleaning R. vitalii from blood of infected dogs. (C) 2011 Elsevier Inc. All rights reserved.