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.

Metabolic Post-feeding Changes in Fat Body and Hemolymph of Dipetalogaster maximus (Hemiptera:Reduviidae)

Lipids and glycogen in fat body as well as the modifications in the wet weight of this organ were evaluated in an unfed insect, Dipetalogaster maximus, on day 5 after adult ecdysis (time 0) and during a 30-day period after ingestion of blood meal. Total lipids, high density lipophorin (HDLp), carbohydrates, total proteins and uric acid were determined in the hemolymph during the same period. Fat body wet weight was maximum on day 10 post-feeding and represented on day 30 only 42% of the maximum weight. Lipids stored in the fat body increased up to day 15 reaching 24% of the total weight of tissue. Glycogen was maximum on day 20, representing approximately 3% of the fat body weight. HDLp represented at all times between 17-24% of the total proteins, whose levels ranged between 35 and 47 mg/ml. Uric acid showed at 20, 25 and 30 days similar levels and significantly higher than the ones shown at days 10 and 15. Hemolymphatic lipids fluctuated during starvation between 3-4.4 mg/ml and carbohydrates showed a maximum on day 15 after a blood meal, decreasing up to 0.26 mg/ml on day 25. The above results suggest that during physiological events such as starvation, the availability of nutrients is affected, involving principally the fat body reserves

Surgical hepatosplenic mansonic schistosomiasis in adolescents: repercussions of the post-treatment schistosomotic burden on the hepatic functional reserve

Schistosomiasis mansoni affects the hepatic functional reserve. Clinical treatment with oxamniquine is not 100% effective and there has been found strain of this parasite resistant to this drug. The aims of this investigation were: (1) to examine the presence of residual parasite burden after medical and surgical treatment on adolescents with surgical schistosomiasis mansoni and (2) to assess the effect on the hepatic functional reserve in patients with and without residual infection. Twenty nine children with hepatosplenic schistosomiasis mansoni and bleeding esophageal varices were treated with oxamniquine. They underwent splenectomy, ligature of the left gastric vein and autologous implantation of spleen tissue into the greater omentum. After a mean post-operative follow up of five years they underwent rectal biopsy for schistosomotic egg search. They were divided in patients with and without infection. In 20 patients the submucosal egg search was negative, however, in 9 it was positive. The hepatic functional reserve in the patients without infection was as follows: 17 were Child-Pugh A and 3 Child-Pugh B. In the patients who were still infected 6 were Child-Pugh A and 3 Child-Pugh B. The chi2 analysis of the hepatic functional reserve showed chi2 = 3.19 - p= 0.07. From the results the following conclusion can be drawn: residual infection or reinfection in the follow up period had not interfered with the distribution of the hepatic functional reserve of the patients in this series. However, there was a trend for a decrease of this parameter in patients with residual infection.

Influence of the blood meal source on the biology of Meccus picturatus Usinger 1939 (Hemiptera: Reduviidae: Triatominae) under laboratory conditions

Aspects related to hatching, time-lapse between presenting the blood meal and beginning of feeding, feeding time, postfeed defecation delay,life time, mortality and fecundity for each stage of Meccus picturatus, life-cycle were evaluated and compared in two cohorts of M. picturatus fed on hens or rabbits. The hatching rate observed for each of the two studied groups of eggs was 78.1% (n = 2298) on the group fed on hens and 82.1% (n = 2704) on that fed on rabbits, and the average time of hatching was 20 days. Mean time-lapse for beginning feeding was under 3 min in nymphal stages and postfeed defecation delay was under 10 min in all stages, in both cohorts. Mean feeding time was significantly (P < 0.05) shorter in triatomines fed on hens than on rabbits. A similar number of nymphs of each cohort, 69 fed on hens (34.5%) and 68 fed on rabbits (34%), completed the cycle. No significantly (P > 0.05) differences were recorded among the average times from NI to adult in the cohort fed on hens (196.8 ± 15.8 days) and the average time in the cohort fed on rabbits (189.5 ± 22.9). The average span in days for each stage fed on hens was not significantly different to the average span for each stage fed on rabbits. The number of blood meals at each nymphal stage varied from 1 to 6 in both cohorts. The mortality rates were higher on fifth nymphal stage, in both cohorts. No significant (P > 0.05) differences were recorded on mortality rates on most nymphal stages of both cohorts. The average number of eggs laid per female from the cohort fed on hens in a 9-month period was 791.1, whereas the average number of eggs in the cohort fed on rabbits was 928.3.

Biological effect of 1-dodecanol in teneral and post-teneral Rhodnius prolixus and Triatoma infestans (Hemiptera: Reduviidae)

Topical application of 1-dodecanol was significantly more toxic against teneral first nymphs (1-3 h old) than post-teneral first nymphs (24 h old). The lethal dose ratios were 711,500 for Rhodnius prolixus and 3613 for Triatoma infestans. No significative difference between LD50 was found when 1-dodecanol was injected in recently hatched adult R. prolixus (1-4 h old) nor in older adults (24 h old). These values were similar to those calculated for deltamethrin (an effective triatomicide), showing that 1-dodecanol had no insecticidal properties when it was applied by injection. Topical application of high dose of 1-dodecanol (1 µg/i) on teneral first nymphs of R. prolixus, produced an interruption of the darkening process of the cuticle, and probably in the development of its physiological properties.

Dried blood spots as a practical and inexpensive source for human immunodeficiency virus and hepatitis C virus surveillance

Passive surveillance of infectious diseases with a high percentage of asymptomatic cases or long incubation periods, such as acquired immunodeficiency syndrome (AIDS), does not reflect the current transmission dynamics. Thus, a multi-strategic surveillance, such as the human immunodeficiency virus (HIV) sentinel surveillance proposed by the World Health Organization (WHO), is necessary. The Brazilian HIV sentinel surveillance was started in May 1992 with this purpose. The objectives of this study were to evaluate the feasibility and costs of HIV and hepatitis C virus (HCV) surveillance using dried blood spots (DBS) collected for neonatal screening of metabolic diseases in the state of Minas Gerais, Brazil. This was accomplished through the comparison of HIV and HCV seroprevalence with previous Brazilian studies. From December 2001 to June 2002, 24,905 newborns were tested for HIV and 4211 for HCV. HIV seroprevalence was 0.25% and the 95% confidence interval (CI) was 0.18, 0.31%; and HCV seroprevalence was 0.71% and the 95% CI was 0.46, 0.97%. These numbers are similar to previous Brazilian studies. Cost in this study was approximately US$ 3.10 per sample, which was roughly one third of the cost of the same exam at the Brazilian HIV sentinel surveillance. We conclude that it is possible and more cost-effective to use DBS for infectious diseases surveillance, albeit it is still necessary to compare these results with the usual sentinel methodology in a concomitant trial.

The use of biodiversity as source of new chemical entities against defined molecular targets for treatment of malaria, tuberculosis, and T-cell mediated diseases: a review

The modern approach to the development of new chemical entities against complex diseases, especially the neglected endemic diseases such as tuberculosis and malaria, is based on the use of defined molecular targets. Among the advantages, this approach allows (i) the search and identification of lead compounds with defined molecular mechanisms against a defined target (e.g. enzymes from defined pathways), (ii) the analysis of a great number of compounds with a favorable cost/benefit ratio, (iii) the development even in the initial stages of compounds with selective toxicity (the fundamental principle of chemotherapy), (iv) the evaluation of plant extracts as well as of pure substances. The current use of such technology, unfortunately, is concentrated in developed countries, especially in the big pharma. This fact contributes in a significant way to hamper the development of innovative new compounds to treat neglected diseases. The large biodiversity within the territory of Brazil puts the country in a strategic position to develop the rational and sustained exploration of new metabolites of therapeutic value. The extension of the country covers a wide range of climates, soil types, and altitudes, providing a unique set of selective pressures for the adaptation of plant life in these scenarios. Chemical diversity is also driven by these forces, in an attempt to best fit the plant communities to the particular abiotic stresses, fauna, and microbes that co-exist with them. Certain areas of vegetation (Amazonian Forest, Atlantic Forest, Araucaria Forest, Cerrado-Brazilian Savanna, and Caatinga) are rich in species and types of environments to be used to search for natural compounds active against tuberculosis, malaria, and chronic-degenerative diseases. The present review describes some strategies to search for natural compounds, whose choice can be based on ethnobotanical and chemotaxonomical studies, and screen for their ability to bind to immobilized drug targets and to inhibit their activities. Molecular cloning, gene knockout, protein expression and purification, N-terminal sequencing, and mass spectrometry are the methods of choice to provide homogeneous drug targets for immobilization by optimized chemical reactions. Plant extract preparations, fractionation of promising plant extracts, propagation protocols and definition of in planta studies to maximize product yield of plant species producing active compounds have to be performed to provide a continuing supply of bioactive materials. Chemical characterization of natural compounds, determination of mode of action by kinetics and other spectroscopic methods (MS, X-ray, NMR), as well as in vitro and in vivo biological assays, chemical derivatization, and structure-activity relationships have to be carried out to provide a thorough knowledge on which to base the search for natural compounds or their derivatives with biological activity.

Mycobacterium bovis identification by a molecular method from post-mortem inspected cattle obtained in abattoirs of Mato Grosso do Sul, Brazil

The presence of Mycobacterium bovis in bovine carcasses with lesions suggestive of tuberculosis was evaluated. Seventy-two carcass samples were selected during slaughter inspection procedures in abattoirs in the state of Mato Grosso do Sul, Brazil. Seventeen (23.6%) of samples showed colonies suggestive of mycobacteria that were confirmed to be acid-fast bacilli by Ziehl-Neelsen staining. Polymerase chain reaction (PCR) using primers specific for M. bovis identified M. bovis in 13 (76.5%) isolates. The PCR-restriction enzyme pattern analysis using gene encoding for the 65-kDa protein and two restriction enzymes identified the remaining four isolates that were represented by two M. tuberculosis complex and two nontuberculous mycobacteria. The results are indicative of infection of slaughter cattle by M. bovis and other mycobacteria in the state of Mato Grosso do Sul.

Regulation of endothelial derived nitric oxide in health and disease

Endothelial nitric oxide synthase (eNOS) is the primary physiological source of nitric oxide (NO) that regulates cardiovascular homeostasis. Historically eNOS has been thought to be a constitutively expressed enzyme regulated by calcium and calmodulin. However, in the last five years it is clear that eNOS activity and NO release can be regulated by post-translational control mechanisms (fatty acid modification and phosphorylation) and protein-protein interactions (with caveolin-1 and heat shock protein 90) that direct impinge upon the duration and magnitude of NO release. This review will summarize this information and apply the post-translational control mechanisms to disease states.

Field trials of low dose Bayluscide on snail hosts of schistosome and selected non-target organisms in sahelian Cameroon

More than 85% of all cases of schistosomiasis in Cameroon occur in the northern sahelian half of the country representing 20% of the population. Several workers have advocated the integrated approach to schistosomiasis control, including snail control, but the death and decay of aquatic organisms, and fish kill that often follows Bayluscide application at the dose of 1g/m³ decrease its acceptability. The present study was designed to assess the effect of lower Bayluscide doses on snail host and non-target fish, frog, the tadpole kill. Bayluscide was applied to study ponds at concentrations of 0, 0.25, 0.5, and 1 g/m³ (ppm). Pre and post application assessment of snails hosts of schistosomes, fish, frog, and tadpole kill were carried out. All 0.25, 0.5, and 1 g/m³ Bayluscide concentrations reduced snail population significantly. Bayluscide concentration of 0.50 g/m³ applied in two rounds of 0.25 g/m³ resulted in high snail mortality and low lethality to fish, frogs, and tadpoles. Further studies are needed to assess the cost-effectiveness of Bayluscide in the control of schistosomiasis following the simplified approach.

Perspectives in the control of infectious diseases by transgenic mosquitoes in the post-genomic era: a review

Arthropod-borne diseases caused by a variety of microorganisms such as dengue virus and malaria parasites afflict billions of people worldwide imposing major economic and social burdens. Despite many efforts, vaccines against diseases transmitted by mosquitoes, with the exception of yellow fever, are not available. Control of such infectious pathogens is mainly performed by vector management and treatment of affected individuals with drugs. However, the numbers of insecticide-resistant insects and drug-resistant parasites are increasing. Therefore, inspired in recent years by a lot of new data produced by genomics and post-genomics research, several scientific groups have been working on different strategies to control infectious arthropod-borne diseases. This review focuses on recent advances and perspectives towards construction of transgenic mosquitoes refractory to malaria parasites and dengue virus transmission.

Brazilian flora extracts as source of novel antileishmanial and antifungal compounds

Natural products have long been providing important drug leads for infectious diseases. Leishmaniasis is a protozoan parasitic disease found mainly in developing countries, and it has toxic therapies with few alternatives. Fungal infections have been the main cause of death in immunocompromised patients and new drugs are urgently needed. In this work, a total of 16 plant species belonging to 11 families, selected on an ethnopharmacological basis, were analyzed in vitro against Leishmania (L.) chagasi, Leishmania (L.) amazonensis, Candida krusei, and C. parapsilosis. Of these plant species, seven showed antifungal activity against C. krusei, five showed antileishmanial activity against L. chagasi and four against L. amazonensis, among them species of genus Plectranthus. Our findings confirm the traditional therapeutic use of these plants in the treatment of infectious and inflammatory disorders and also offer insights into the isolation of active and novel drug prototypes, especially those used against neglected diseases as Leishmaniasis.

Options for clinical trials of pre and post-natal treatments for congenital toxoplasmosis

Clinical trials comparing different drug regimens and strategies for the treatment of congenital toxoplasmosis and its clinical manifestations in the liveborn child in different clinical settings should aim at formally evaluating the net benefit of existing treatments and at developing new therapeutic options. Currently, there is no ideal drug for congenital toxoplasmosis; future research should focus on the screening of new active drugs and on their pre-clinical and early clinical development, with a focus on pharmacokinetic/dynamic studies and teratogenicity. For the prenatal treatment of congenital toxoplasmosis, a trial comparing spiramycine to pyrimethamine-sulphadiazine and placebo would allow a formal estimation of the effect of both drugs in infected pregnant women. In newborn children, the net benefit of pyrimethamine-sulphadiazine should also be formally assessed. These trials will be implemented in settings where prenatal screening for Toxoplasma gondii is currently implemented. Trials should be carefully designed to allow for translation to other settings and modelling tools like cost-effectiveness analysis should be used to provide clinicians and founders with the best available evidence to establish recommendations.