Pre- and post-treatment immunodiagnostic evaluation in human schistosomiasis mansoni

Schistosomiasis control seems to be different in countries were low parasitic burden and asymptomatic clinical patients are the features of majority of cases. Immunological methods must substitute the traditional coprologic techniques used for some decades in the Control Program. Circumoval Precipitin Test (COPT), intradermal test and ELISA with soluble egg antigen (SEA) are evaluated for using as tools for seroepidemiologic studies. COPT and ELISA were performed after treatment to known their utility when impact of chemotherapy must be assessed. One hundred sixty five persons were followed up 3, 6, 9 and 12 months after treatment. The mean sensitivity of CPT studied by age groups was 95.6% which is very important considering that 88.4% of the studied population excreted less than 100 egg/gr of feces, while sensitivity of intradermal test was 58.2%. Children showed the highest ractivity to COPT. When treatment is effective, COPT reactivity progressively disminish until become negative one year later. In the non cure group, the COPT reactivity disminished but never below 20%. ELISA-SEA did not modify one year after treatment. Effort should be made to isolate fractions of eggs Schistosoma mansoni whose antibodies disappear after treatment.

Forma aguda ou toxêmica da esquistossomose mansoni

The acute toxemic form of schistosomiasis mansoni is studied under anatomic and clinical point of view, according to classification made by Neves, Raso and Bagliolo in 1975. The first phase is characterized by the following facts: cutaneous (immediate and late) manifestations; high fever or in progressive elevation; intense diaphoresis abdominal disconfort; intense acquous diarrhea; dehidratation; loss of weight, dry cough; painful hepatosplenomegaly; discreet lymphademegaly, progressive increase of blood leucocytes and eosinophisles; radiological pulmonary alterations; absence of alterations in serum protein and hepatic functional tests; the hepatic function byopsy shows focus of acute hepatitis. The second stage or properly named toxemic period was clinically characterized by the neat aggravation of the previously observed phenomena. At last, the evolutive course of the disease has implication derived not only of the worm's presence, but from the intense dissemination of eggs in the tissue. In the pre-laying phase one studied the forms of cercarian dermatitis, prodromic and innapparent. In the post laying phase, the properly named acute toxemic form, with its types: pseudocholeraic, pseudotyphous, pseudodysenteric-bacillary, pseudonophritic, pseudoenterovirotic, the reactivated, the ischemic enterocolitis and others; whenever possible clinical and anatomic correlation will be made.

Parasitological diagnosis of schistosomiasis mansoni: fecal examination and rectal biopsy

Even with all progress in the search of sensitive and methods for the immunological diagnosis of schistosomiasis, the microscopic detection of eggs of the parasite in the stool still remains the most widely used tool for the actual diagnosis of active infection. Among the coproscopic methods, Kato's technic modified by Katz et al (Kato/Katz) has the advantages of higher sensitivity, the possibility of egg quantification, its low operational cost and its feasibility in areas with minimal infra-structure. The oorgram of the rectal mucosa is valuable in initial clinical trials of schistosomicides, when it is needed to observe egg morphology in tissue. It could be an alternative method for individual diagnosis, being more sensitive than a single stool exam in low intensity infection. However, the increased sensitivity of a higher number of fecal exams makes that invasiveprocedure unnecessary. In the assessment of cure of schistosomiasis, Kato/Katz method (three fecal samples in one, three and six months after treatment) and the rectal biopsy four months after treatment, are equally reliable.

Esquistossomose mansoni: tratamento medicamentoso

It is the specific treatment of mansoni schistosomiasis that aims to act directed on the parasite, through chemotherapy. Constitutes fundamental indication to the treatment of schistosomiasis active forms, that is, these determined by the presence of living eggs in the feces or in material from rectal biopsy, since eventual contra indications are respected. Two are the medicaments actually used: oxamniquine, used in the single dosage of 15mg/kg, V.O. for adults and 20mg/kg V.O. for children divided in two doses, offers a percentage of 30 to 40% of cures, evaluated by quantitative "oogram" and prazinquantel, in the single dose of 60 mg/kg V.O., presents a cure index of 30% however in seriate doses, of 60mg/kg during 3 days or 30mg/kg, 6 days, cure percentage is elevated to 95% evaluated by oogram. The evaluation of the treatment by quantitative or qualitative examination methods does not show the same sensibility. The percentage of cure according to feces examination, the quantitative of Kato-Katz or the qualitative (sedimentation), showed indexes from 90 to 100% for either one of the drugs, even in single dose, which evidences the difference of methodology of therapeutic evaluation. Tolorance to both medicaments is from good to regular, with collateral effects in 30 to 40% of the patients.

Human schistosomiasis mansoni: studies on in vitro granuloma modulation

Infection with Schistosoma mansoni induces humoral and T cell mediated responses and leads to delayed hipersensitivity that results in granulomatous inflamatory disease around the parasite eggs. Regulation of these responses resulting in a reduction in this anti-egg inflamatory disease is appsrently determined by idiotypic repertoires of the patient, associated with genetic background and multiple external factors. We have previously reported on idiotype/anti-idiotype-receptor transactions in clinical human schistosomiasis. These findings support a hypothesis that anti-SEA cross-reactive idiotypes develop in some patients during the course of a chronic infection and participate in regulation of anti-SEA cellular immune responses. We repport here on experiments wich extend those observations to the regulation of granulomatous hypersensitivity measured by an in vitro granuloma model. T cells from chronic intestinal schistosomiasis patients were stimulated in vitro with anti-SEA idiotypes and assayed in an autologous in vitro granuloma assay for modulation of granuloma formation. These anti-SEA idiotype reactive T cells were capable of regulating autologous in vitro granuloma formation. This regulatory activity, initiated with stimulatory anti-SEA idiotypic antibodies, was antigenically specific and was dependent on the present of intact (F(ab')2 immunoglobulin molecules. The ability to elicit this regulatory activity appears to be dose dependent and is more easily demonstrated in chronically infected intestinal patients or SEA sensitized individuals. These data support the hypothesis that anti-SEA cross reactive idiotypes are important in regulating granulomatous hypersensitivy in chronic intestinal schistosomiasis patients and these cross-reactive idiotypes appear to play a major role in cell-cell interactions which result in the regulation of anti-SEA cellular immune responses.

Milky spots reactions to schistosomal mansoni infection

Milky spots (MS), considered by the authors as a Coelomatic Lympho-myelopoietic Organ (CLMO), present a strong reactivity during experimental schistosomal mansoni infection, characterized by an increase of lymphocytes, macrophages, plasmocytes, mast cells, neutrophils and expression of eosinophil metaplasia. Intraperitoneal injection of purified Schistosoma mansoni (Sm) eggs provoked a rise in the number and size of MS, which developed the sessile marginal and pedunculated types. The authors conclude that egg antigens are, at least partially, responsible for MS reactivity during Sm infection.

Vitellogenesis in insects and other groups: a review

The eggs from oviparous organisms contain large amounts of vitellus, or yolk, wich are utilized by the growing embryo. Vitellogenesis is the process of vitellus accumulation and involves massive heterosynthetic synthesis of the protein vitellogenin (Vg) and its deposition in the oocyte. This work summarizes data on Vg structure, synthesis, uptake by oocytes and its fate during embryogenesis. The hormonal control of vitellogenesis and its tissue, sex and temporal regulation are also discussed. Where it is available, data on structure and expression of Vg-coding genes are reviewed. Insect vitellogenesis is priorized although other oviparous animal groups outside insects are also treated.

The distribution of intestinal helminth infections in a rural village in Guatemala

Fecal egg count scores were used to investigate the distribution and abundance of intestinal helminths in the population of a rural village. Prevalences of the major helminths were 41% with Ascaris lumbricoides 60% with Trichuris trichiura and 50% with Necator americanus. All three parasites showed a highly aggregated distribution among hosts. Age/prevalence and age/intensity profiles were typical for both A. lumbricoides and T. trichiura with the highest worm burdens in the 50-10 year old children. For hookworm both prevalence and intensity curves were convex in shape with maximum infection levels in the 30-40 year old age class. Infected females had higher burdens of T. trichiura than infected males in all age classes of the population; there were no other effects of host gender. Analysis of associations between parasites within hosts revealed strong correlations between A. lumbricoides and T. lumbricoides and T. trichiura. Individuals with heavy infections of A. lumbricoides and T. trichiura showed highly significant aggregation within households. Associations between a variety of household features and heavy infections with A. lumbricoides and T. trichiura are described.

Raillietina (Raillietina) guaricana n. sp. (Cestoda-Davaineidae), parasite of wild rats from the environmental protection area of Guaricana, Paraná, Brazil

Raillietina (Raillietina) guaricanae n. sp. is described from the wild rats Oryzomys intermedius, O. nigripes and O. ratticeps, captured in the Environmental Protection Area of Guaricana, from November 1988 to December 1989. Raillietina (Railietina) guaricanae n. sp. is closely related to the Neotropical mammalian Raillietina, however it differs by the fewer number of rostellar hooks, and tests different number of eggs capsules and host species. The number of known species of Raillietina (Raillietina), parasites of mammals in the Neotropical Region, is increased to four.

Effects of gamma irradiation on the reproductive capacity and the longevity of Panstrongylus (Hemiptera: Reduviidae)

The effects of radiation on the reproductive capacity and the longevity of Panstrongylus magistus were studied. An indirect correlation between longevity and radiation doses was observed. Males were more affected than females. Longevity of females submitted to 10 Gy was not different when compared to controls. Some of the irradiated males copulated and in these cases semen was transferred to females, but only few eggs were laid. Fertility was seriously affected in all irradiated groups, decreasing with increasing intensity of dose. The dose of 80 Gy induced sterility in males and females. Gelatinous spermatophores that were expelled by females irradiated with 20 and 40 Gy, may be a consequence of irradiation that induced modification in the bursa copulatrix pH.

Life cycle and influence of age and feeding on the first mating of Triatoma mazzottii (Hemiptera: Reduviidae)

A cohort of 100 eggs of Triatoma mazzottii Usinger was studied to obtain information on its life cycle. Egg incubation took 24 days; mean duration of 1st, 2nd, 3rd, 4th, and 5th instar nymphs was 27, 36, 39, 46 and 64 days respectively; mean time from egg to adult was 236 days. The total duration of the nymphal stages was 212 days. The total nymph mortality in cohort was 16.3% and the embryonic egg mortality was 14.0%. The grater mortality occured in the 2nd instar. The average number of eggs/female/week was 9.8 during 15 weeks of observation. Of the total eggs laid (2,514), only 58.7% hatched. The total of insects that achieved the adult stage (72), 38 were females (52.8%), and 34 were males (47.2%). The influence of age and feeding on the first mating of T. mazzottii were also studied. It was found that the first mating depended on the male's age and it was on the average 30 days after the last imaginal molt. The female could be mating since 2nd days after the imaginal life. The nutritional status did not play an important role in the capacity of the insect for the first mating.

Capillaria hepatica: a cause of septal fibrosis of the liver

Fine, long, fibrous septa were observed as a late change developing in the acinar zone III of the liver of rats experimentally infected with the helminth Capillaria hepatica. Hepatic septal fibrosis begun 30 days after inoculation of embryonated eggs into the stomach of rats and became clearly evident from the 40th day onwards. Experimental observation was undertaken for 170 days. Septal fibrosis increased progressively with time and was most marked when the parasitic nodules formed around larvae, disintegrating worms and eggs were involving. Septal fibrosis of the liver has not been previously recognized as a manifestation of hepatic capillariasis. The presence of sequestered parasite antigens, probably being slowly released within the liver, appears to be a major factor in the pathogenesis of hepatic septal fibrosis observed in rats with C. hepatica infection.

Dynamic of population-dynamics in a medically important snail species Lymnaea (Radix) Luteola (Lamarck)

The life-cycle parameters of the snail Lymnaea (Radix) luteola and the factors influencing the same have been studied under laboratory conditions. Ins each month, from July 1990 to June 1991, a batch of 100 zero-day old individual were considered for studies. The snails of April batch survived for 19.42 days while those in December batch survived for 87.45 days. The May batch individual though survived for 65.67 days gained maximum shell size (15.84 mm in length) and body weight (419.87 mg). All individuals of April batch died prior to attainment of sexual maturity. In the remaining 11 batches the snails became sexually mature between 32 and 53 days. At this stage, they were with varying shell lengths, 9.3 mm to 13,11 mm in respect to batches. The reproduction period varied from 1-67 days. An individual laid, on an average, 0,25 (March batch) to 443.67 (May batch) eggs in its life-span. A batch of such snails would leave 24312, 22520, 720268, 80408, 76067, 418165, 214, 9202, 0, 0, 2459386 and 127894 individuals at the end of 352nd day. Since the environmental conditions were almost similar the 'dynamic' of population dynamics seems to be involved with the 'strain' of the snail individuals of the batches concerned.

Egg-laying induced by insemination in Biomphalaria snails

Contrasting with many populations of Biomphalaria glabrata and B. straminea previously dealt with in this laboratory, which when reared in isolation deposit self-fertilized eggs without apparent restraint, isolated individuals of the former species from São Sebastião do Passé, Bahia state, and of the latter from Porto Alegre, Rio Grande do Sul state, show a high degree of self-sterility, laying egg capsules with a few usually abortive, rarely viable egg cells, or just jellylike masses without egg cells. When two individuals are paired they readily copulate, usually withing 24 hr deposit one of more egg capsules containing many eggs, and egg-laying continues up to exhaustion of stored allosperm. So far this aspect of reproductive biology has been only observed in a number of populations of the planorbid species Helisoma duryi, and should be viewed as a populational rather than specific characteristic. Since sterility is not overcome by courtship, copulation and insemination by individuals of a different species, the stimulating factor that causes ovulation in the studied self-sterile individuals is considered to be present in the conspecific allosperm.

Climatic change in northeastern Brazil: paleoparasitological data

Trichuris eggs were observed in Kerodon rupestris coprolites dated 9,000 years before present, collected in archeological sites of São Raimundo Nonato, northeastern Brazil. However, present day local rodents seem not to be infected by the parasite, suggesting its disappearence due to climatic changes.