Successful Feeding of Amblyomma coelebs (Acari: Ixodidae) Nymphs on Humans in Brazil: Skin Reactions to Parasitism.

Identifying the tick species that successfully feed on humans would increase knowledge of the epidemiology of several tick-borne diseases. These species salivate into the host, increasing the risk of pathogen transmission. However, there is a lack of data in the literature regarding the ticks that prefer to feed on humans. Herein, we describe the successful feeding of Amblyomma coelebs Neumann nymphs on two of the authors after accidental tick bites occurred during field surveys in two preserved areas of Mato Grosso do Sul, Brazil. One of the host-parasite interactions was closely monitored, and the tick development, gross host skin alterations, and related sensations are presented.

Cryptic sexual populations account for genetic diversity and ecological success in a widely distributed, asexual fungus-growing ant.

Sex and recombination are central processes in life generating genetic diversity. Organisms that rely on asexual propagation risk extinction due to the loss of genetic diversity and the inability to adapt to changing environmental conditions. The fungus-growing ant species Mycocepurus smithii was thought to be obligately asexual because only parthenogenetic populations have been collected from widely separated geographic localities. Nonetheless, M. smithii is ecologically successful, with the most extensive distribution and the highest population densities of any fungus-growing ant. Here we report that M. smithii actually consists of a mosaic of asexual and sexual populations that are nonrandomly distributed geographically. The sexual populations cluster along the Rio Amazonas and the Rio Negro and appear to be the source of independently evolved and widely distributed asexual lineages, or clones. Either apomixis or automixis with central fusion and low recombination rates is inferred to be the cytogenetic mechanism underlying parthenogenesis in M. smithii. Males appear to be entirely absent from asexual populations, but their existence in sexual populations is indicated by the presence of sperm in the reproductive tracts of queens. A phylogenetic analysis of the genus suggests that M. smithii is monophyletic, rendering a hybrid origin of asexuality unlikely. Instead, a mitochondrial phylogeny of sexual and asexual populations suggests multiple independent origins of asexual reproduction, and a divergence-dating analysis indicates that M. smithii evolved 0.5-1.65 million years ago. Understanding the evolutionary origin and maintenance of asexual reproduction in this species contributes to a general understanding of the adaptive significance of sex.

Predictors of invasive mechanical ventilation use in patients with acute decompensated pulmonary hypertension admitted to the intensive care unit.

In acute decompensated pulmonary hypertension, elevated nonrespiratory SOFA was associated with a higher use of invasive mechanical ventilation independently of the hypoxaemia on ICU admission and pulmonary hypertension severity https://bit.ly/3YdOHpn.

Lung ultrasonography derived B-line scores as predictors of left ventricular end-diastolic pressure and pulmonary artery wedge pressure.

BACKGROUND: Non-invasive assessment of elevated left ventricular end-diastolic pressure (LVEDP) and pulmonary artery wedge pressure (PAWP) in patients with heart diseases is challenging. Lung ultrasonography (LUS) is a promising modality for predicting LVEDP and PAWP. METHODS: Fifty-seven stable ambulatory patients who underwent right and left heart catheterization were included. Following the procedures, LUS was performed in twenty-eight ultrasonographic zones, and the correlation between five different LUS derived B-line scores with LVEDP and PAWP was examined. RESULTS: The B-line index correlated with LVEDP and PAWP, with coefficients of 0.45 (p = 0.006) and 0.30 (p = 0.03), respectively. B-line index showed an AUC of 0.76 for identifying LVEDP > 15 mmHg (p = 0.01) and an AUC of 0.73 for identifying PAWP > 15 mmHg (p = 0.008). Overall, scores performances were similar in predicting LVEDP or PAWP > 15 mmHg. A B-line index ≥ 28 was significantly associated with LVEDP > 15 mmHg (OR: 9.97) and PAWP > 15 mmHg (OR: 6.61), adjusted for age and indication for heart catheterization. CONCLUSIONS: LUS derived B-line scores are moderately correlated with PAWP and LVEDP in patients with heart diseases. A B-line index ≥ 28 can be used to predict elevated LVEDP and PAWP with high specificity.

External validation of the OPALS prediction model for in-hospital mortality in patients with acute decompensated pulmonary hypertension.

In this external validation of the OPALS prediction model for in-hospital mortality in patients with acute decompensated pulmonary hypertension admitted to the intensive care unit, discrimination was very good and similar to the derivation cohort https://bit.ly/3sa8oQy.

Simulation-based Assessment to Measure Proficiency in Mechanical Ventilation among Residents.

Background: Mechanical ventilation (MV) skills are essential for clinicians caring for critically ill patients, yet few training programs use structured curricula and appropriate assessments. Objective structured clinical exams (OSCEs) have been used to assess clinical competency in many areas, but there are no OSCE models focused on MV. Objective: To develop and validate a simulation-based assessment (SBA) with an OSCE structure to assess baseline MV competence among residents and identify knowledge gaps. Methods: We developed an SBA using a lung simulator and a mechanical ventilator, and an OSCE structure, with six clinical scenarios in MV. We included internal medicine residents at the beginning of their rotation in the respiratory intensive care unit (ICU) of a university-affiliated hospital. A subset of residents was also evaluated with a validated multiple-choice exam (MCE) at the beginning and at the end of the ICU rotation. Scores on both assessments were normalized to range from 0 to 10. We used Cronbach's α coefficient to assess reliability and Spearman correlation to estimate the correlation between the SBA and the MCE. Results: We included 80 residents, of whom 42 also completed the MCE examinations. The final version of the SBA had 32 items, and the Cronbach's α coefficient was 0.72 (95% confidence interval [CI], 0.64-0.81). The average SBA score was 6.2 ± 1.3, and performance was variable across items, with 80% correctly adjusting initial ventilatory settings and only 12% correctly identifying asynchrony. The MCE had 24 questions, and the average score was 7.6 ± 2.4 at the beginning of the rotation and 8.2 ± 2.3 at the end of the rotation (increase of 0.6 points; 95% CI, 0.30-0.90; P < 0.001). There was moderate correlation between the SBA and the MCE (rho = 0.41; P = 0.002). Conclusion: We developed and validated an objective structured assessment on MV using a pulmonary simulator and a mechanical ventilator addressing the main competencies in MV. The performance of residents in the SBA at the beginning of an ICU rotation was lower than the performance in MCE, highlighting the need for greater emphasis on practical skills in MV during residency.

Effect of parathion-methyl on Amazonian fish and freshwater invertebrates: a comparison of sensitivity with temperate data.

Parathion-methyl is an organophosphorous insecticide that is widely used in agricultural production sites in the Amazon. The use of this pesticide might pose a potential risk for the biodiversity and abundance of fish and invertebrate species inhabiting aquatic ecosystems adjacent to the agricultural fields. Due to a lack of toxicity data for Amazonian species, safe environmental concentrations used to predict the ecological risks of parathion-methyl in the Amazon are based on tests performed with temperate species, although it is unknown whether the sensitivity of temperate species is representative for those of Amazonian endemic species. To address this issue, the acute toxic effect (LC(50)-96 h) of parathion-methyl was assessed on seven fish and five freshwater invertebrate species endemic to the Amazon. These data were used to compare their pesticide sensitivity with toxicity data for temperate species collected from the literature. The interspecies sensitivity was compared using the Species Sensitivity Distribution (SSD) concept. The results of this study suggest that Amazonian species are no more, or less, sensitive to parathion-methyl than their temperate counterparts, with LC(50) values ranging from 2900 to 7270 microg/L for fish and from 0.3 to 319 microg/L for freshwater arthropods. Consequently, this evaluation supports the initial use of toxicity data of temperate fish and freshwater invertebrate species for assessing the effects of parathion-methyl on Amazonian freshwater ecosystems.

Acute and chronic toxicity of the fungicide carbendazim to the earthworm Eisenia fetida under tropical versus temperate laboratory conditions.

Research efforts into the potential side-effects of pesticides on beneficial organisms have focused on temperate test species and conditions. There is thus a need for studies into the ecotoxicity of a vaster range of pesticides under tropical conditions. The present study therefore aimed to compare the acute and chronic toxicity of the fungicide carbendazim to the earthworm Eisenia fetida under tropical and temperate conditions. To this end, laboratory toxicity tests were conducted with a tropical and European strain of E. fetida, using different artificial (OECD and TAS) and natural (LUFA and TNS) soils, and under different test temperatures (20 °C and 28 °C). In the acute lethality tests with artificial soils, the tropical strain of E. fetida was three to four order of magnitude less sensitive than the European strain, which is ascribed to the higher test temperature and (hence) higher microbial activity/pesticide degradation. The tropical strain was particularly sensitive in the tropical natural soil, which was attributed to the low pH (3.9) of this soil. The chronic toxicity tests overall also showed a lower sensitivity of the tropical strain on reproduction. These findings thus support the use of toxicity data generated under temperate conditions in tropical pesticide effect assessments. However, intensive agricultural practices in the tropics may dictate that exposure levels (and hence potentially also risks) are higher.

Biology and life cycle of Amblyomma incisum (Acari: Ixodidae).

Amblyomma incisum Neumann is a major tick species in the Atlantic Forest of Brazil. Tapir is the main host for adult ticks and a high aggressiveness of nymphs to humans has been reported. In this work data on the biology and life cycle of this tick species is presented for the first time. It was shown that horse is a suitable host for A. incisum adults and rabbit for larvae and nymphs. It was also shown that A. incisum is a big tick species (mean engorged female weight of 1.96 g) with a long life cycle which lasts 262.3 days when maintained at 27 degrees C and 85% RH. These laboratory conditions were, however, inappropriate and egg hatching rate (1.2%) was very low. Nevertheless egg hatching of ticks in a forest patch increased considerably (72.2%) indicating that this A. incisum population is highly dependent on a forest-like environment.

Species diversity and seasonality of free-living ticks (Acari: Ixodidae) in the natural habitat of wild Marsh deer (Blastocerus dichotomus) in Southeastern Brazil.

This study evaluated the presence and seasonal activity of free-living ticks in remaining marsh areas by the Paraná river, in Brazil. Eight field trips (once per season) for collection of ticks were performed during 2 years. Using CO2 traps, dragging, and visual inspection of vegetation, five free-living tick species were collected, in the following order of abundance: Amblyomma cajennense, Amblyomma dubitatum, Amblyomma triste, Amblyomma coelebs, and Amblyomma nodosum. The seasonal pattern of A. cajennense was characterized by the highest peaks for adult ticks in the summer/spring months, for nymphs in the winter and for larvae in the autumn and winter. A. dubitatum and A. triste presented similar seasonal patterns characterized by peaks of adult ticks in the autumn. Nymphs of A. dubitatum peaked in the winter of the first year and in the winter/spring of the second year. A. triste was the only species to be collected in significantly higher numbers in the marsh than in surrounding drier areas such as forest patches. Among domestic animals living close the marsh areas, horses were infested by Anocentor nitens, A. cajennense, and Boophilus microplus, bovines were infested solely by B. microplus, and dogs were infested by Rhipicephalus sanguineus. Adults of A. triste showed to be well adapted to the marsh environment. This result, at least partially, explains local previous observations on the association of A. triste with marsh deer, as this vertebrate host inhabits mainly the marsh area.

Atmospheric versus biological sources of polycyclic aromatic hydrocarbons (PAHs) in a tropical rain forest environment.

To distinguish between pyrogenic and biological sources of PAHs in a tropical rain forest near Manaus, Brazil, we determined the concentrations of 21 PAHs in leaves, bark, twigs, and stem wood of forest trees, dead wood, mineral topsoil, litter layer, air, and Nasutitermes termite nest compartments. Naphthalene (NAPH) was the most abundant PAH with concentrations of 35 ng m(-3) in air (>85% of the sum of 21PAHs concentration), up to 1000 microg kg(-1) in plants (>90%), 477 microg kg(-1) in litter (>90%), 32 microg kg(-1) in topsoil (>90%), and 160 microg kg(-1) (>55%) in termite nests. In plants, the concentrations of PAHs in general decreased in the order leaves > bark > twigs > stem wood. The concentrations of most low-molecular weight PAHs in leaves and bark were near equilibrium with air, but those of NAPH were up to 50 times higher. Thus, the atmosphere seemed to be the major source of all PAHs in plants except for NAPH. Additionally, phenanthrene (PHEN) had elevated concentrations in bark and twigs of Vismia cayennensis trees (12-60 microg kg(-1)), which might have produced PHEN. In the mineral soil, perylene (PERY) was more abundant than in the litter layer, probably because of in situ biological production. Nasutitermes nests had the highest concentrations of most PAHs in exterior compartments (on average 8 and 15 microg kg(-1) compared to <3 microg kg(-1) in interior parts) and high PERY concentrations in all compartments (12-86 microg kg(-1)), indicating an in situ production of PERY in the nests. Our results demonstrate that the deposition of pyrolytic PAHs from the atmosphere controls the concentrations of most PAHs. However, the occurrence of NAPH, PHEN, and PERY in plants, termite nests, and soils at elevated concentrations supports the assumption of their biological origin.

Origin and alteration of organic matter in termite mounds from different feeding guilds of the Amazon rainforests.

The impact of termites on nutrient cycling and tropical soil formation depends on their feeding habits and related material transformation. The identification of food sources, however, is difficult, because they are variable and changed by termite activity and nest construction. Here, we related the sources and alteration of organic matter in nests from seven different termite genera and feeding habits in the Terra Firme rainforests to the properties of potential food sources soil, wood, and microepiphytes. Chemical analyses comprised isotopic composition of C and N, cellulosic (CPS), non-cellulosic (NCPS), and N-containing saccharides, and molecular composition screening using pyrolysis-field ionization mass spectrometry (Py-FIMS). The isotopic analysis revealed higher soil δ13C (-27.4‰) and δ15N (6.6‰) values in nests of wood feeding Nasutitermes and Cornitermes than in wood samples (δ13C = -29.1‰, δ15N = 3.4‰), reflecting stable-isotope enrichment with organic matter alterations during or after nest construction. This result was confirmed by elevated NCPS:CPS ratios, indicating a preferential cellulose decomposition in the nests. High portions of muramic acid (MurAc) pointed to the participation of bacteria in the transformation processes. Non-metric multidimensional scaling (MDS) revealed increasing geophagy in the sequence Termes < Embiratermes < Anoplotermes and increasing xylophagy for Cornitermes < Nasutitermes., and that the nest material of Constrictotermes was similar to the microepiphytes sample, confirming the report that Constrictotermes belongs to the microepiphyte-feeders. We therewith document that nest chemistry of rainforest termites shows variations and evidence of modification by microbial processes, but nevertheless it primarily reflects the trophic niches of the constructors.

Antibody and blood leukocyte response in Rhipicephalus sanguineus (Latreille, 1806) tick-infested dogs and guinea pigs.

The dog is considered to be the natural host of Rhipicephalus sanguineus and is unable to develop appreciable resistance even after repeated feedings. The guinea pig develops strong resistance after one infestation with adult ticks. Antibody (IgG) titres against tick salivary gland antigens (SGAs) and blood leukocyte numbers in dogs and guinea pigs undergoing experimental R. sanguineus tick infestations were measured to detect a possible correlation with susceptibility or resistance of hosts. Since infested dogs develop an immediate hypersensitivity reaction to R. sanguineus antigens, total and anti-R. sanguineus SGA IgE levels were also measured in this host species. IgG and IgE antibody levels were determined by an enzyme-linked immunosorbent assay (ELISA) along three consecutive infestations of both hosts. Most dogs and guinea pigs displayed low IgG levels against R. sanguineus SGAs, though marked differences in individual response were observed. Although dog's total serum IgE levels increased significantly after infestations, no change in the amount of anti-salivary gland IgE was detected. Total and differential blood cell counts were determined in dogs and guinea pigs during primary and secondary infestation. In dogs, a tertiary infestation and a subsequent higher infestation level were also evaluated. Infested dogs did not display any alteration in blood leukocyte counts throughout the experiment. Guinea pigs, on the other hand, developed a significant basophilia during primary infestation which increased further during secondary infestation. These data reveal similarities and differences in the reactions of resistant and non-resistant hosts to ticks. They contribute for the understanding of such host-parasite relationships and will hopefully aid in the development of immune control of ticks.

The first report of Rickettsia spp. in Amblyomma nodosum in the State of Mato Grosso do Sul, Brazil.

Ticks are vectors of various pathogens, including Rickettsia spp., which are responsible for causing an emerging disease of global significance. In the present study, an epidemiological survey was performed to identify Rickettsia spp. of the spotted fever group (SFG) in ticks and wild hosts in a native forest adjacent to livestock farming activity. The ticks and blood were evaluated by a hemolymph test and by PCR using the primers CS78 and CS323, which target a partial sequence of the enzyme citrate synthase (gltA) gene. Positive samples by PCR were further tested with the primers Rr190.70p and Rr190.602n, which target a 532-bp fragment of the rickettsial 190-kDa outer membrane protein gene (ompA). In addition, an indirect immunofluorescence assay (IFA) was performed to detect antibodies against Rickettsia spp. in horses that inhabited the same area. From the 43 animals that were captured, 192 ticks were collected; the ticks belonged to the species Amblyomma cajennense, A. ovale, and A. nodosum. All blood samples and hemolymph tests were negative. Four samples of A. nodosum that were collected from Tamandua tetradactyla were positive for Rickettsia spp. by PCR, and 8 samples of horse serum displayed titers greater than or equal to 1:64 by IFA. The phylogenetic analysis based on the DNA sequence of the ompACG gene demonstrated that Rickettsia spp. CG (the canadensis group) segregate in the same cluster as Rickettsia parkeri strain COOPERI, with a bootstrap value of 78%. These results indicate that Rickettsia spp. CG circulate among the tick population in the study area, which has a constant presence of livestock and humans. This may be the same species of Rickettsia that was recorded in A. nodosum throughout the Atlantic forest.

Risk assessment of pesticides for soils of the Central Amazon, Brazil: comparing outcomes with temperate and tropical data.

The risk of 11 pesticides to the soil environment was assessed in a 3-tiered approach at 4 sites located in Central Amazon, near Manaus, the capital of the Amazonas State in Brazil. Toxicity-exposure ratios (TERs), as routinely used for the registration of pesticides in the European Union, were calculated. First, the predicted environmental concentration (PEC) values in soil on the basis of real application rates and soil properties but temperate DT50 (degradation time of 50%) values were compared with temperate effect values (earthworm LC50s; median lethal concentrations), both gained from literature. Second, the risk assessment was refined by the use of DT50 values from tropical soils (measured for 7 compounds and estimated for 4) but still with temperate effect values because only a few results from tests performed under tropical conditions are available. Third, the outcome of this exercise was evaluated in a plausibility check with the use of the few results of effect tests, which were performed under tropical conditions. However, the lack of such data allowed this check only for 6 of 11 pesticides. The results are discussed in light of pesticide use in the Amazon in general, as well as compared with the registration status of these pesticides in other countries. Finally, suggestions are given for which kinds of studies are needed to improve the environmental risk assessment of pesticides in tropical regions.

Biological aspects of Amblyomma brasiliense (Acari: Ixodidae) under laboratory conditions.

Although Amblyomma brasiliense Aragão 1908 has been reported as one of the most aggressive ticks to humans in Brazil, information about the biology of this tick species is virtually inexistent. This work reports data on the life cycle of A. brasiliense fed on rabbits and pigs and maintained in an incubator at 20 degrees C, 90% RH and 12 h of light for off-host development. Tick yield of adult females fed on pigs and rabbits was 81.2% and 58.3%, respectively. Females fed on pigs had mean engorgement weight of 862.3 mg and egg mass of 208 mg, while females fed on rabbits had mean engorgement weight of 606.1 mg and egg mass of 160 mg; these values did not differ statistically between host species. Feeding period of female ticks fed on pigs (10 days) was significantly shorter than that on rabbits (17 days). Mean preoviposition period was slightly longer (35.9 days) for ticks fed on pigs than on rabbits (30 days). The minimum incubation period of eggs of ticks from both host species was similar and over 100 days. Egg production efficiency was low for females fed on both hosts (less than 30% and 20% for ticks from pigs and rabbits, respectively). More than 55% of larvae and 79% of nymphs fed on rabbits, set free inside the feeding chambers, engorged successfully. These ticks attained an engorgement weight of 1.3 and 18.2 mg, respectively, and fed for approximately 5 days. The minimum pre-molt period was 30 days for engorged larvae and over 44 days for nymphs. Molting success was low, less than 50% in the case of larvae and less than 20% for nymphs. Further studies are required to better determine the off-host requirements of this tick species.

Effects of the fungicide benomyl on earthworms in laboratory tests under tropical and temperate conditions.

Soil organisms play a crucial role in the terrestrial ecosystem. Plant protection products (PPPs) are known to affect soil organisms and might have negative impacts on soil functions influenced by these organisms. Little research has been performed to date on the impact of PPPs on tropical soil ecosystems. Therefore, in this study it was investigated whether the effects of the fungicide benomyl (chosen as a model substance) differ between tropical and temperate regions and whether data generated under temperate conditions can be used for the Environmental Risk Assessment (ERA) in tropical regions. The effect of benomyl on earthworms was evaluated in acute and chronic laboratory tests modified for tropical conditions. These tests were performed at two temperatures (20 degrees C and 28 degrees C) and with two strains (temperate and tropical) of the compost worm Eisenia fetida. The fungicide was spiked in two natural and two artificial soils. In addition to the organization for economic cooperation and development (OECD) artificial soil, a tropical artificial soil (TAS), containing a tropical fern product (xaxim) instead of peat, was developed in this study. The results from the laboratory tests and a literature review showed that the effects of benomyl were, on average, lower under tropical conditions (LC(50): 450-630 mg active ingredient (a.i.)/kg; EC(50): 0.8-12.9 mg a.i./kg) than under temperate conditions (LC(5)0: 61-67 mg a.i./kg; EC(50): 1.0-1.6 mg a.i./kg) by a maximum factor of 10.3 (acute tests) and 12.9 (chronic tests). This result might be caused by an increased degradation of benomyl, and/or its first metabolite carbendazim, at higher temperatures, but a different sensitivity of the two worm strains cannot be ruled out. Despite the lower toxicity under tropical conditions and assuming comparable application rates, a preliminary assessment confirms the risk of benomyl to soil invertebrates under both conditions.

Ticks (Acari: Ixodidae) parasitizing humans in an Atlantic rainforest reserve of Southeastern Brazil with notes on host suitability.

While conducting projects on ticks from deer and on tick ecology in animal trails in an Atlantic rainforest reserve in Southeastern Brazil, researchers of our group were bitten by ticks several times. Some of these episodes were recorded. Three species of adult ticks attached to humans: Amblyomma brasiliense Aragão, Amblyomma incisum Neumann, and Amblyomma ovale Koch. Eight nymphal attachments with engorgement on humans were recorded. From these, six molted to adults of A. incisum, one to an adult of A. brasiliense, and one had an anomalous molting, therefore the adult tick could not be properly identified. Local reactions to tick attachment varied among individual hosts from almost imperceptible to intense. Especially itching, but hyperemia and swelling as well, were prominent features of the reaction. Overall it can be affirmed that human beings can be a physiologically suitable host species for ticks in the Atlantic rainforest and that itching was an important if not the major component of the resistance to tick bite.

[Childhood scabies: a different entity]. / Sarna infantil: una entidad diferente.

Epidemiological, clinical, diagnostic and therapeutic aspects that make scabies a clinical entity with a special personality in the pediatric field, are reviewed. On the epidemiological aspects, a special mention of its unsuspected frequency in this age is made. Scabies is an endemic disease in our country among the more deprived people. On the clinical aspects, the great importance of clinical history and distribution of skin lesions for the early diagnosis is pointed out. Some "alert pointers" are described for this early diagnosis. On the therapeutic field, the importance of the primary care prevention is discussed, and the drug approach for its relieve is commented.