Serological survey for Chagas disease in the rural areas of Manaus, Coari, and Tefé in the Western Brazilian Amazon

INTRODUCTION: Deforestation, uncontrolled forest, human population migration from endemic areas, and the large number of reservoirs and wild vectors naturally infected by Trypanosoma cruzi promote the endemicity of Chagas disease in the Amazon region. METHODS: We conducted an initial serological survey (ELISA) in a sample of 1,263 persons; 1,095 (86.7%) were natives of the State of Amazonas, 666 (52.7%) were male, and 948 (75.1%) were over 20 years old. Serum samples that were found to be reactive, indeterminate, or inconclusive by indirect immunofluorescence (IFI) or positive with low titer by IFA were tested by Western blot (WB). Serologically confirmed patients (WB) were evaluated in terms of epidemiological, clinical, ECG, and echocardiography characteristics. RESULTS: Fifteen patients had serologically confirmed T. cruzi infection, and 12 of them were autochthonous to the state of Amazonas, for an overall seroprevalence of 1.2% and 0.9% for the state of Amazonas. Five of the 15 cases were males, and the average age was 47 years old; most were farmers with low education. One patient who was not autochthonous, having originated from Alagoas, showed right bundle branch block, bundle branch block, and anterosuperior left ventricular systolic dysfunction with an ejection fraction of 54%. CONCLUSIONS: The results of this study ratify the importance of monitoring CD cases in Amazonia, particularly in the state of Amazonas.

Seroepidemiological monitoring in sentinel animals and vectors as part of arbovirus surveillance in the state of Mato Grosso do Sul, Brazil

INTRODUCTION: From February-September 2010, seroepidemiological surveys were conducted on non-human primates and transmitter vector capture was used to investigate the possible circulation of arboviruses in the municipalities of Bonito, Campo Grande, and Jardim, State of Mato Grosso do Sul, Brazil. METHODS: A total of 65 primates from the wild and captivity were used, and potential vectors were captured using Castro and dip nets. Serum samples were tested at the Instituto Evandro Chagas, State of Pará, using the hemagglutination inhibition test to detect total antibodies against 19 different arboviruses. Virus isolation was attempted from serum samples and arthropod suspensions using newborn mice and the C6/36 cell line clone. In addition, identification of the vector species was conducted. RESULTS: From the 19 serum samples from Campo Grande, 1 sample had a 1:20 titer for Flavivirus. From the 35 samples collected in Bonito, 17 samples had antibodies to arboviruses, 4 (11.4%) were positive for Alphavirus, and 5 (14.2%) were positive for Flavivirus. Monotypic reactions were observed for the Mayaro (n = 10) and Oropouche (n = 5) viruses, and 6 (17.1%) samples had titers for >1 virus. We captured 120 Culicidae individuals that were potential arbovirus transmitters in Jardim; however, all the samples were negative for the viruses. CONCLUSIONS: Mato Grosso do Sul has a variety of vertebrate hosts and transmission vectors, thereby providing ideal conditions for the emergence or reemergence of arboviruses, including some pathogenic to human beings.

Antigens of worms and eggs showed a differentiated detection of specific IgG according to the time of Schistosoma mansoni infection in mice

INTRODUCTION: The correlation between the immunological assay and the antibody titer can offer a tool for the experimental analysis of different phases of the disease. METHODS: Two simple immunological assays for Schistosoma mansoni in mice sera samples based on specific IgG detection for worms soluble antigens and eggs soluble antigens were standardized and evaluated in our laboratory. Fifty mice were used in negative and positive groups and the results obtained by enzyme-linked immunosorbent assays (ELISA) assays were compared with the number of worms counted and the IgG titers at different times of infection. RESULTS: Data showed that ELISA using adult worm antigens (ELISA-SWAP) presented a satisfactory correlation between the absorbance value of IgG titers and the individual number of worms counted after perfusion technique (R²=0.62). In addition, ELISA-SWAP differentially detected positive samples with 30 and 60 days post infection (p=0.011 and 0.003, respectively), whereas ELISA using egg antigens (ELISA-SEA) detected samples after 140 days (p=0.03). CONCLUSIONS: These data show that the use of different antigens in immunological methods can be used as potential tools for the analysis of the chronological evolution of S. mansoni infection in murine schistosomiasis. Correlations with human schistosomiasis are discussed.

Seroprevalence and seroincidence of Leptospira infection in dogs during a one-year period in an endemic urban area in Southern Brazil

INTRODUCTION: Leptospirosis is a zoonosis that affects both humans and animals. Dogs may serve as sentinels and indicators of environmental contamination as well as potential carriers for Leptospira. This study aimed to evaluate the seroprevalence and seroincidence of leptospirosis infection in dogs in an urban low-income community in southern Brazil where human leptospirosis is endemic. METHODS: A prospective cohort study was designed that consisted of sampling at recruitment and four consecutive trimestral follow-up sampling trials. All households in the area were visited, and those that owned dogs were invited to participate in the study. The seroprevalence (MAT titers ≥100) of Leptospira infection in dogs was calculated for each visit, the seroincidence (seroconversion or four-fold increase in serogroup-specific MAT titer) density rate was calculated for each follow-up, and a global seroincidence density rate was calculated for the overall period. RESULTS: A total of 378 dogs and 902.7 dog-trimesters were recruited and followed, respectively. The seroprevalence of infection ranged from 9.3% (95% CI; 6.7 - 12.6) to 19% (14.1 - 25.2), the seroincidence density rate of infection ranged from 6% (3.3 - 10.6) to 15.3% (10.8 - 21.2), and the global seroincidence density rate of infection was 11% (9.1 - 13.2) per dog-trimester. Canicola and Icterohaemorraghiae were the most frequent incident serogroups observed in all follow-ups. CONCLUSIONS: Follow-ups with mean trimester intervals were incapable of detecting any increase in seroprevalence due to seroincident cases of canine leptospirosis, suggesting that antibody titers may fall within three months. Further studies on incident infections, disease burden or risk factors for incident Leptospira cases should take into account the detectable lifespan of the antibody.

Toxoplasma gondii infection: seroprevalence and associated risk factors among primary schoolchildren in Lagos City, Southern Nigeria

INTRODUCTION: Toxoplasma gondii infection has been described as the most widespread zoonotic infection of humans and other animals. Information concerning T. gondii infection among schoolchildren is unavailable in Lagos City, Nigeria. METHODS: This cross-sectional study investigated the seroprevalence and risk factors associated with T. gondii infection among primary schoolchildren (PSC) from a community located in the center of Lagos, southern Nigeria, from November 2013 to March 2014. A total of 382 PSC were screened for the presence of sera anti-T. gondii antibodies using a latex agglutination test (TOXO Test-MT, Tokyo, Japan). A cutoff titer of ≥ 1:32 was considered positive, while titers ≥ 1:1,024 indicated high responders. Questionnaires were also used to obtain data on possible risk factors from parents/guardians. RESULTS: The overall seroprevalence was 24% (91/382), and 83.5% (76/91) of seropositive PSC were classified as high responders. Among the risk factors tested, including contact with cats and soil, consumption of raw meat and vegetables, and drinking unboiled water, none showed statistical significance after multivariate adjustment. No associations were observed among age, gender, body mass index (BMI), and parents' occupation/educational level. CONCLUSIONS: The findings in this study show evidence of active infection, and hence, there is need for urgent preventive measures in this city. Further investigation is required to clarify the transmission routes. Policy makers also need to initiate prevention and control programs to protect pregnant women and immunocompromised patients in particular because they are more severely affected by T. gondii infection.

Hemolytic disease of the newborn due to anti-U

Anti-U is a rare red blood cell alloantibody that has been found exclusively in blacks. It can cause hemolytic disease of the newborn and hemolytic transfusion reactions. We describe the case of a female newborn presenting a strongly positive direct antiglobulin test due to an IgG antibody in cord blood. Anti-U was recovered from cord blood using acid eluate technique. Her mother presented positive screening of antibodies with anti-U identified at delivery. It was of IgG1 and IgG3 subclasses and showed a titer of 32. Monocyte monolayer assay showed moderate interaction of Fc receptors with maternal serum with a positive result (3.1%). The newborn was treated only with 48 hours of phototherapy for mild hemolytic disease. She recovered well and was discharged on the 4th day of life. We conclude that whenever an antibody against a high frequency erythrocyte antigen is identified in brown and black pregnant women, anti-U must be investigated.

Pulmonary hemorrhage as a manifestation of systemic lupus erythematosus

The authors report a case of a 19-year-old woman admitted for the investigation of fever and hemolytic anemia for the previous 2 months. As an inpatient, she had convulsions and sudden loss of consciousness, developing hemoptysis, hypoxia, and respiratory insufficiency. Examination showed pericardial effusions on the echocardiogram and bilateral alveolar condensations on the thoracic radiograph. A hypothetical diagnosis of systemic lupus erythematosus was made, and measurement of the antinuclear factor was requested along with daily pulse therapy methylprednisolone, in spite of which the outcome was fatal. Afterwards, the result of the antinuclear factor test was positive, with a titer of 1:5120, showing a fine punctiform pattern, fulfilling the criteria for systemic lupus erythematosus according to the American College of Rheumatology. Secondary pulmonary hemorrhage in this connective tissue disease is an uncommon but serious complication that involves a high level of mortality in spite of intensive treatment, as is also reported in the literature.

Índice lipásido Seabra: seu valor no diagnóstico da tuberculose

The determination of blood lipase has been proposed by SEABRA as a method for detecting predisposition to initial or subsequent stages of tuberculosis; normal subjects having high titers (8-12 units), tuberculous patients low ones (5-7), falling to zero in advanced stages of the disease. An assay of the method has been made by the AA. in sera of 238 non tuberculous subjects (419 tests) and 207 tuberculous ones (456 tests) following the technical procedures described by SEABRA. All of them had their Roentgenographies taken at the same day of blood collection. Factors interfering with blood lipase values in tuberculosis are discussed. A relationship between the course of the disease and the serum lipase could not be confirmed. High and low values were found in initial as well as in advanced cases. Our results are in agreement with those recorded in the literature (Figs. I and II). It seems that the general condition, rather than pulmonary lesions are responsible for the blood lipase values. There was no direct relationship between blood lipase titer and severity of pulmonary tuberculosis; however the data presented in this paper do not agree with such correlation, stated by SEABRA, FERNANDES and VICENTE.

On the adjuvant effect of aluminum hydroxide for mice

Linear relationships were found between the dose of A1(OH)3 adjuvant and the titer of anti-OVA antibodies formed by BDF1 mice. Mice immunized with OVA, DNP-KLH and then boosted with DNP-OVA formed anti-DNP antibodies only when A1(OH)3 was added to the injection of DNP-KLH; addition of A1(OH)3 to the priming injection of OVA decreased, rather than increased antibody formation.

Effects of precocene and azadirachtin in Rhodnius prolixus: some data on development and reproduction

The results presented in this paper clearly indicate that precocene and azadirachtin are effective inhibitors of moulting and reproduction in the hemipteran Rhodnius prolixus. The time of application is important and only applications of these substances early in the intermoulting period cause their effects in nymphs. The inhibition of moulting is fully reversed by ecdysone therapy. Precocene and azadirachtin also affected drastically the oogenesis and egg deposition in this insect. Precocene-induced sterilization is reversed by application of juvenile hormone III. However, this hormone is unable to reverse the effect of azadirachtin on reproduction. Ecdysteroid titers in nymphs and adult females are decreased by these treatments. In vitro analysis suggest that precocene and azadirachtin may act directly on the prothoracic glands and ovaries producing ecdysteroids. Based on these and other findings the possible mode of action of these compounds on the development and reproduction of Rhodnius prolixus is discussed.

Role of a mouse monoclonal IgE antibody in passive transfer of immunity to Schistosoma japonicum infection

We have been able to produce a mouse monoclonal IgE antibody specific to an adult worm antigen extracted from Schistosoma japonicum (Sj). The antibody was able to elicit passive cutaneous anaphylaxis in the rat skin against Sj with the highest titer of 1:256,000 but did not cross-react with S. mansoni antigen. The antibody recognized a 97-kDa molecule expressed on the surface of mechanically transformed schistosoma of S. japonicum. Passive transfer of the antibody into mice in the early stage of challenge infection resulted in a partial but significant reduction of recovery of adult worms. Induction of eosinophilia by an oral administration of embryonated eggs of Toxocara canis prior to challenge infection enhanced the reduction.

Effects of azadirachtin in Rhodnius prolixus: data and hypotheses

The effects of azadirachtin A, a tetranortriterpenoid from the neem tree Azadirachta indica J., on both development and interaction between Trypanosoma cruzi, the causative agent of Chagas' disease, and its vector Rhodnius prolixus were studied. Given through a blood meal, a dose-rsponse relationship of azadirachtin was established using antifeedant effect and ecdysis inhibition as effective parameters. A singlo dose of azadirachtin A was able to block the onset of mitosis in the epidermis and ecdysteroid titers in the hemnolymph, determined by radioimmuneassay, were too low for an induction of ecadysis. The survival of T. cruzi was also studied in R. prolixus treated with the drug. If the trypomastigotes were fed in presence of azadirachtin A the number of parasites drastically decreased. If the drug was applied after infection of the bug with T. cruzi, the parasite was still abolished from the gut. If the insect was pretreated with azadirachtin A before infection the same observation was obtained. A single dose of azadirachtin A was enough for a permanent resistance of the insect host against its reinfection with T. cruzi and for blocking the ecdysis for a long time. The effects of azadirachtin A on the hormonal balance of the host and growth inhibition of the parasite will be discussed on the basis of the present results.

Effects of proallatotoxins (precocenes) on the development and reproduction of Rhodnius prolixus: some data

Proallatotoxins, and particularly preconcenes, are exceptionally promising models for studying Rhodnius prolixus physiology and for comparison with other natural compounds with anti-hormonal activities. Effects of preconcenes on feeding, development and reproduction of R. prolixus are being detailed. The precocenes reveal significant effects on feeding, moulting cycle (inducing precocious metamorphosis and ecdysial stasis), and reproduction of these insect. The mechanism of action of proallatotoxins was discussed based on the corpus allatum cytotoxic effect and on the ecdysteroid biosynthesis in prothoracic glands and ovaries. Further studies of these compounds on R. prolixus are need and will hopefully reveal other unesplored points regarding the action of the proallatotoxins on insects.

Household-based malaria control in a highly endemic area of Africa (Tanzania): determinants of transmission and disease and indicators for monitoring - Kilombero Malaria Project

The Kilombero Malaria Project (KMP) attemps to define opperationally useful indicators of levels of transmission and disease and health system relevant monitoring indicators to evaluate the impact of disease control at the community or health facility level. The KMP is longitudinal community based study (N = 1024) in rural Southern Tanzania, investigating risk factors for malarial morbidity and developing household based malaria control strategies. Biweekly morbidity and bimonthly serological, parasitological and drug consumption surveys are carried out in all study households. Mosquito densities are measured biweekly in 50 sentinel houses by timed light traps. Determinants of transmission and indicators of exposure were not strongly aggregated within households. Subjective morbidity (recalled fever), objective morbidity (elevated body temperature and high parasitaemia) and chloroquine consumption were strongly aggregated within a few households. Nested analysis of anti-NANP40 antibody suggest that only approximately 30% of the titer variance can explained by household clustering and that the largest proportion of antibody titer variability must be explained by non-measured behavioral determinants relating to an individual's level of exposure within a household. Indicators for evaluation and monitoring and outcome measures are described within the context of health service management to describe control measure output in terms of community effectiveness.

Protection of aouts monkeys after immunization with recombinant antigens of Plasmodium falciparum

The genus Aotus spp. (owl monkey) is one of the WHO recommended experimental models for Plasmodium falciparum blood stage infection, especially relevant for vaccination studies with asexual blood stage antigens of this parasite. For several immunization trials with purified recombinant merozoite/schizont antigens, the susceptible Aouts kenotypes II, III, IV and VI were immunized with Escherichia coli derived fusion proteins containg partial sequences of the proteins MSAI (merozoite surface antigen I), SERP (serine-strech protein) and HRPII (histidine alanine rich protein II) as well as with a group of recombinant antigens obtained by an antiserum raised against a protective 41 kD protein band. The subcutaneous application (3x) of the antigen preparations was carried out in intact animals followed by splenectomy prior to challange, in order to increase the susceptibility of the experimental hosts to the parasite. A partial sequence of HRPII, the combination of three different fusion proteins of the 41 kD group and mixture of two sequences of SERP in the presence of the modified Al(OH)3 adjuvant conferred significant protection against a challange infection with P. falciparum blood stages (2-5 x 10 (elevado a sexta potência) i. RBC). Monkey immunized with the MS2-fusion protein carrying the N-terminal part of the 195 kD precursor of the major merozoite surface antigens induced only marginal protection showing some correlation between antibody titer and degree of parasitaemia. Based on the protective capacity of these recombinant antigens we have expressed two hybrid proteins (MS2/SERP/HRPII and SERP/MSAI/HRPII) in E. coli containing selected partial sequences of SERP, HRPII and MSAI. Antibodies raised against both hybrid proteins in rabbits and Aotus monkeys recognize the corresponding schizont polypeptides. In two independent immunization trials using 13 animals (age 7 months to 3 years) we could show that immunization of Aotus monkeys with either of the two hybrid proteins administered in an oil-based well tolerated formulation protected the animals frm a severe experimental P. falciparum (strain Palo Alto) infection.