Ecological relations between mangrove leaf litter and the spatial distribution of the gastropod Melampus coffeus in a fringe mangrove forest

Leaf litter represents a food source to many organisms that may directly contribute to organic matter decomposition. In addition, the physical presence of these vegetal detritus contributes for the modification of some environmental areas and produce microhabitats that may act as a refuge against predators and desiccation for many animals. The pulmonate gastropod Melampus coffeus (Linnaeus, 1758) (Ellobiidae) is a very common specie in Atlantic Coast mangrove forests and feeds on fallen mangrove leaves. It was hypothesized that the spatial distribution of Melampus coffeus is directly affected by mangrove leaf litter biomass deposition. Thus, this research aimed at evaluating the spatial distribution of these gastropods in relation to the biomass of mangrove leaf litter through a twelve-month period. The study area was established in the middle estuary of Pacoti River, state of Ceará, Brazil where two adjacent zones with different topographic profiles were determined. Samples of Melampus coffeus and leaf litter were collected monthly, throughout a year, from the mangrove ground surface. The results indicated that the presence of twigs in mangrove litter favor the occupation by smaller individuals of M. coffeus, probably because smaller individuals are more susceptible to predator attacks and desiccation than larger ones, and twigs and branches may provide a safe microhabitat.

The effect of subminimal inhibitory concentrations of penicillin on growth rate and haemolysin activity of group G Streptococcus

The influence of the subminimal inhibitory concentrations (1/3 and 1/4 of the MIC) of penicillin on growth rate and on haemolysin production of a strain of group G Streptococcus was studied. It was shown that 1/3 of the MIC almost completely inhibited the bacterial growth, but it was not able to inhibit haemolysin activity in the culture supernate. The generation time of bacteria grown in 1/4 of the MIC was approximately twice longer than that of the control culture. In all cultures, the haemolysin, after being produced (or liberated), reached a peak and decreased to low levels, which could suggest that group G Streptococcus produces some end products of metabolism that are able to inhibit haemolysin activity.

Acidic ribosomal proteins and histone H3 from Leishmania present a high rate of divergence

Another additional peculiarity in Leishmania will be discussed about of the amino acid divergence rate of three structural proteins: acidic ribosomal P1 and P2b proteins, and histone H3 by using multiple sequence alignment and dendrograms. These structural proteins present a high rate of divergence regarding to their homologous protein in Trypanosoma cruzi. At this regard, L. (V.) peruviana P1 and T. cruzi P1 showed 57.4% of divergence rate. Likewise, L. (V.) braziliensis histone H3 and acidic ribosomal P2 protein exhibited 31.8% and 41.7% respectively of rate of divergence in comparison with their homologous in T. cruzi.

Effect of Sequential Cold Shocks on Survival and Molting Rate in Triatoma infestans Klug

The survival and molting incidence in Triatoma infestans, a vector of Chagas disease, were investigated following sequential shocks at 0ºC in fifth instar nymphs under moderate fasting and full nutritional conditions. The shocks were separated by intervals of 8 h and 24 h at 30ºC. The results indicated that in terms of insect survival, T. infestans is tolerant to a single cold shock at 0ºC even for 12 h, or to sequential cold shocks, regardless of the nutritional state of the specimens. In terms of molting rate, fasting enhanced the tolerance to sequential cold shocks, but did not exceed the tolerance acquired by fully-nourished specimens, except when cold shocks were separated by an 8 h interval at 30ºC. The protective action elicited by fasting was assumed to be additive to that induced by a single mild cold shock or sequential cold shocks. The cold-tolerance response of T. infestans may have favoured its survival in areas of South America with low temperatures, even considering that this species is predominantly associated with human habitats.

Epidemiology of Chagas disease in Guatemala: infection rate of Triatoma dimidiata, Triatoma nitida and Rhodnius prolixus (Hemiptera, Reduviidae) with Trypanosoma cruzi and Trypanosoma rangeli (Kinetoplastida, Trypanosomatidae)

A five-year domiciliary collection in the 22 departments of Guatemala showed that out of 4,128 triatomines collected, 1,675 were Triatoma dimidiata (Latreille, 1811), 2,344 were Rhodnius prolixus Stal 1859, and only 109 were T. nitida Usinger 1939. The Chagas disease parasite, Trypanosoma cruzi, was found in all three species. Their natural infection rates were similar in the first two species (20.6%; 19.1%) and slightly lower in T. nitida(13.8%). However there was no significant difference in the infection rates in the three species (p = 0.131). T. dimidiata males have higher infection rates than females (p = 0.030), whereas for R. prolixus there is no difference in infection rates between males and females (p = 0.114). The sex ratios for all three species were significantly skewed. More males than females were found inside houses for T. dimidiata (p < 0.0001) and T. nitida (p = 0.011); a different pattern was seen for R. prolixus (p = 0.037) where more females were found. Sex ratio is proposed as an index to show the mobility of T. dimidiata in different populations. T. dimidiata is widely distributed in the country, and is also the main vector in at least ten departments, but R. prolixus with higher vectorial capacity is an important vector in at least two departments.

Infection rate of Babesia spp. sporokinetes in engorged Boophilus microplus from an area of enzootic stability in the State of Minas Gerais, Brazil

The infection rates of Babesia sporokinetes in engorged Boophilus microplus were evaluated during a 2-year period in a dairy farm located in an area of enzootic stability. Every 14 days engorged females were collected from calves and from adult animals. Ticks were incubated at 27 ± 0.5ºC and 80-90% relative humidity and Babesia infection rates were determined by microscopic examination of Giemsa-stained hemolymph smears. After 52 collections, 2105 ticks were obtained, from which 982 were collected from calves and 1123 from cows. The total Babesia infection rate was 10%, however the incidence was higher (p < 0.05) in ticks collected from calves (17.5%) than in those collected from cows (3.6%). Females collected from cows showed the highest infection rates in January, March, and August, and absence of infection in April and May. Ticks feeding on calves were infected throughout the experimental period. The infection rates of engorged females collected from naturally infected calves that were artificially infested with Babesia-free-larvae of B. microplus gradually decreased until the calves were four months old. No differences were observed among infection rates of ticks collected from calves maintained under natural conditions.

Intradermal vaccination of adults with three low doses (2 µg) of recombinant hepatitis B vaccine. I. Seroconversion rate and adverse effects

A total of 250 dentists (53.6% men and 46.4% women), with a mean age of 35.1 ± 9.8 years, were submitted to serological tests for the diagnosis of hepatitis B (HB) - HBsAg, anti-HBs, anti-HBc, HBeAg, and anti-HBe - using a radioimmunoassay. One or more of these markers were detected in 78 individuals (31.2%) who were excluded from the group to be vaccinated. Of the 172 HB-susceptible individuals, 135 (78.5%) responded to the call and were intradermally injected with three 2 µg doses of the Belgian HB recombinant vaccine, applied at an interval of one month between the 1st and 2nd dose and of five months between the 2nd and 3rd dose. A new determination of HB markers carried out 50 days after the 3rd dose showed that 110 (81.5%) individuals had become anti-HBs positive (65.5% good responders and 34.5% poor responders). Mean serum anti-HBs titer of these 110 dentists was 42.4 U S/N, similar in both sexes. The adverse effects analyzed in 106 dentists were: (a) local: pain (12.3%), burning sensation (14.1%), pruritus (25.5%), erythema (28.3%), local heat (18.9%), and a hypochromic spot (32.1%); (b) systemic (4.7%): discomfort in two patients, and fever, anorexia, and asthenia in one patient each. Intradermal administration of a fourth 2 µg vaccine dose to 39 dentists (poor or non-responders) increased the total number of anti-HBs-positive individuals from 110 (81.5%) to 114 (84.4%), with the number of good responders increasing from 72 (65.5%) to 85 (74.6%). We conclude that the Belgian recombinant vaccine applied in the scheme used here induces a high rate of seroconversion and causes only mild and transitory adverse effects.

Effect of food on immature development, consumption rate, and relative growth rate of Toxorhynchites splendens (Diptera: Culicidae), a predator of container breeding mosquitoes

Food utilization by the larvae of Toxorhynchites splendens (Wiedemann) was studied in the laboratory by offering larvae of Aedes aegypti Linnaeus, Anopheles stephensi (Liston), and Culex quinquefasciatus (Say). Quantitative analyses of data indicated that immature development was significantly faster with increase in food availability. The regression analysis showed that the degrees of the relationship between immature duration (Id) and food availability were higher when offered early instars of prey (first and second instars) than late instars. Consumption rate (Cr) of the predator increased with increase in food availability and this relationship was highly significant when larvae of An. stephensi were offered as food. Consumption rate to food level decreased with increase in the age class of the prey. There was a significant negative correlation between Id and Cr. This aspect helps to increase population turnover of T. splendens in a shorter period when the prey is abundant. Conversely, the predator compensated the loss in daily food intake at low food level by extending Id thereby attains the minimum threshold pupal weight for adult emergence. There was an increase in the relative growth rate (RGR) of the predator when An. stephensi was offered as prey and this was related to the high protein content of the prey per body weight. There was a positive correlation between Cr and RGR. This adaptive life characteristic strategy of this predator is useful for mass-rearing for large scale field release programmes in the control of container breeding mosquitoes is discussed.

The effects of temperature change on the infection rate of Biomphalaria glabrata with Schistosoma mansoni

The aim of this study was to investigate the influence of temperature on the development of Schistosoma mansoni infections in Biomphalaria glabrata. The snails were infected at 15, 20, and 30ºC, and the cercarial release was analyzed after 30 and 60 days post-infection. Our results showed that a decrease in the temperature has a substantial influence on the development of S. mansoni infection in B. glabrata, with significant differences (p < 0.05) between 15 and 30ºC. These data could provide a better understanding of the epidemiological aspects of schistosomiasis.

Seroepidemiology of hepatitis B virus infection and high rate of response to hepatitis B virus Butang®vaccine in adolescents from low income families in Central Brazil

In order to evaluate the seroepidemiology and response to Butang® vaccine in adolescents from low income families in Central Brazil, blood samples of 664 adolescents were tested for hepatitis B surface antigen (HBsAg), hepatitis B core antibody (anti-HBc), and hepatitis B surface antibody (anti-HBs) markers, and multiple logistical regression analysis was carried out to determine variables associated with hepatitis B virus (HBV) infection markers. further, three 20 µg butang® vaccine doses were offered to all susceptible individuals (n = 304). Among those who accepted them (n = 182), the seroresponse was evaluated in 170 individuals by quantitative anti-HBs. an overall hbv prevalence of 5.9% was found: four adolescents were HBsAg positive, 24 were anti-HBc, anti-HBs-reactive, and 11 were anti-HBc only. The analyse of risk factors showed that age 16-19 years, place of birth outside Goiás, school B and body piercing were statistically associated with HBV infection markers (p < 0.05). All 170 adolescents responded to butang®, and a geometric mean titer (gmt) of 4344 mui/ml was obtained. these results reinforce the importance of hepatitis b vaccine in adolescents despite of the hbv regional endemicity, and suggest that three doses of 20 µg of the butang® should guarantee protective anti-hbs levels to individuals at a critical time for hepatitis b acquiring such as latter adolescence and adulthood.

Man biting rate seasonal variation of malaria vectors in Roraima, Brazil

Malaria control has been directed towards regional actions where more detailed knowledge of local determinants of transmission is of primary importance. This is a short report on range distribution and biting indices for Anopheles darlingi and An. albitarsis during the dry and rainy season that follows river level variation in a savanna/alluvial forest malaria system area in the Northern Amazon Basin. Distribution range and adult biting indices were at their highest during the rainy season for both An. darlingi and An. albitarsis. During the rainy season the neighboring alluvial forest was extensively flooded. This coincided with highest rates in malaria transmission with case clustering near the river. As the river receded, anopheline distribution range and density decreased. This decrease in distribution and density corresponded to a malaria decrease in the near area. An exponential regression function was derived to permit estimations of An. darlingi distribution over specified distances. Anopheline spatio-temporal variations lead to uneven malaria case distribution and are of important implications for control strategies.

IgG and IgG2 antibodies from cattle naturally infected with Anaplasma marginale recognize the recombinant vaccine candidate antigens VirB9, VirB10, and elongation factor-Tu

Anaplasma marginale is an important vector-borne rickettsia of ruminants in tropical and subtropical regions of the world. Immunization with purified outer membranes of this organism induces protection against acute anaplasmosis. Previous studies, with proteomic and genomic approach identified 21 proteins within the outer membrane immunogen in addition to previously characterized major surface protein1a-5 (MSP1a-5). Among the newly described proteins were VirB9, VirB10, and elongation factor-Tu (EF-Tu). VirB9, VirB10 are considered part of the type IV secretion system (TFSS), which mediates secretion or cell-to-cell transfer of macromolecules, proteins, or DNA-protein complexes in Gram-negative bacteria. EF-Tu can be located in the bacterial surface, mediating bacterial attachment to host cells, or in the bacterial cytoplasm for protein synthesis. However, the roles of VirB9, VirB10, and TFSS in A. marginale have not been defined. VirB9, VirB10, and EF-Tu have not been explored as vaccine antigens. In this study, we demonstrate that sera of cattle infected with A. marginale, with homologous or heterologous isolates recognize recombinant VirB9, VirB10, and EF-Tu. IgG2 from naturally infected cattle also reacts with these proteins. Recognition of epitopes by total IgG and by IgG2 from infected cattle with A. marginale support the inclusion of these proteins in recombinant vaccines against this rickettsia.

Prevalence of acute toxoplasmosis infection among 41,112 pregnant women and the mother-to-child transmission rate in a public hospital in South Brazil

Untreated acute toxoplasmosis among pregnant women can lead to serious sequelae among newborns, including neurological impairment and blindness. In Brazil, the risk of congenital toxoplasmosis (CTox) has not been fully evaluated. Our aim was to evaluate trends in acute toxoplasmosis prevalence from 1998-2005, the incidence of CTox and the rate of mother-to-child transmission (MTCT). A cross-sectional study was undertaken to dentify patients who fit the criteria for acute toxoplasmosis during pregnancy. Exposed newborns were included in a historical cohort, with a median follow-up time of 11 months, to establish definite diagnosis of CTox. Diagnoses for acute infection in pregnancy and CTox were based on European Research Network on Congenital Toxoplasmosis criteria. In 41,112 pregnant women, the prevalence of acute toxoplasmosis was 4.8/1,000 women. The birth prevalence of CTox was 0.6/1,000 newborns [95% confidence interval (CI): 0.4-0.9]. During the follow-up study, 12 additional cases were detected, increasing the CTox rate to 0.9/1,000 newborns (95% CI: 0.6-1.3). Among the 200 newborns exposed to Toxoplasma gondii,there were 37 babies presenting diagnostic criteria of CTox, leading to an MTCT rate of 18.5% (95% CI: 13.4-24.6%). The additional cases identified during follow-up reinforce the need for serological monitoring during the first year of life, even in the absence of evidence of congenital infection at birth.

Molluscicidal activity of Hammada scoparia (Pomel) Iljin leaf extracts and the principal alkaloids isolated from them against Galba truncatula

The molluscicidal activity of Hammada scoparia leaf extracts and the principal alkaloids isolated from them (carnegine and N-methylisosalsoline) were tested against the mollusc gastropod, Galba truncatula, the intermediate host of Fasciola hepatica in Tunisia. The results indicated that the molluscicidal activity was correlated with the presence of alkaloids. A significant molluscicidal value, according to the World Health Organization, was found with the methanol extract (LC50 = 28.93 ppm). Further fractionation of the methanolic extract led to the isolation of two principal alkaloids: carnegine and N-methylisosalsoline. These alkaloids are isoquinolines that have not previously been characterised for their molluscicidal activity. The N-methylisosalsoline possesses the highest molluscicidal activity (LC50 = 0.47 μM against G. truncatula).

Co-infections associated with human immunodeficiency virus type 1 in pregnant women from southern Brazil: high rate of intraepithelial cervical lesions

Human immunodeficiency virus type 1 (HIV-positive) pregnant women require specific prophylactic and therapeutic approaches. The efficacy of established approaches is further challenged by co-infection with other sexually transmitted diseases (STDs). The objective of this study was to determine the prevalence of co-infections in pregnant women infected with different HIV-1 subtypes and to relate these findings, together with additional demographic and clinical parameters, to maternal and infant outcomes. Blood samples from pregnant women were collected and tested for syphilis, hepatitis B virus (HBV) and hepatitis C virus (HCV). Human papillomavirus (HPV) diagnosis was evaluated by the presence of alterations in the cervical epithelium detected through a cytopathological exam. Medical charts provided patient data for the mothers and children. Statistical analyses were conducted with STATA 9.0. We found a prevalence of 10.8% for HCV, 2.3% for chronic HBV, 3.1% for syphilis and 40.8% for HPV. Of those co-infected with HPV, 52.9% presented high-grade intraepithelial lesions or in situ carcinoma. Prematurity, birth weight, Apgar 1' and 5' and Capurro scores were similar between co-infected and non-co-infected women. The presence of other STDs did not impact maternal and concept outcomes. More than half of the patients presenting cervical cytology abnormalities suggestive of HPV had high-grade squamous intraepithelial lesions or cervical cancer, evidencing an alarming rate of these lesions.