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Abstract Background Rhipicephalus (Boophilus) microplus is the most important tick species affecting cattle in the world. Under field conditions, the non-parasitic phase of R. (B.) microplus is unknown in the Amazon biome, including Brazil. The present study aimed to evaluate the non-parasitic phase of R. (B.) microplus in field (grass plots) and laboratory conditions. Methods The study was conducted from September 2020 to April 2022 in an Amazonian region (Maranhão State, Brazil). We evaluated the biological parameters of R. (B.) microplus under laboratory and field conditions. Engorged females were exposed to experimental conditions every 14 days, totaling 20 months of study. The following biological parameters were observed: pre-oviposition period, egg mass incubation period, and maximum larval survival period. Results Abiotic data (e.g., temperature and humidity) varied little throughout the year. Precipitation was the factor that varied the most throughout the year (dry ~ 30 mm3 and rain 400 mm3), and the parameters of pre-oviposition and pre-hatching are longer during the rainy season. A possible negative effect of the dry season on the percentage of hatched eggs was observed. Larval longevity in the plots of both control and free females was short (mean ~ 50–60 days), below that recorded for larvae under controlled conditions (mean ~ 95 days). Conclusions Rhipicephalus (Boophilus) microplus was able to complete its non-parasitic phase by producing host-seeking larvae in the pasture during all months of the study. The results indicate that R. (B.) microplus can complete up to six generations per year in biome Amazon. To our knowledge, this is the highest number of annual generations for R. (B.) microplus in Latin America. Graphical Abstract

Tick abnormalities have been unusual in nature, and they can be divided into local and general. In the present study, external morphological anomalies were described in 31 individual adult ticks of 15 different species of Ixodidae, which were collected on wild hosts (20 ticks), domestic hosts (7 ticks), and in the environment (4 ticks) in 11 states of Brazil from 1998 to 2022. Among the 31 tick specimens, 14 (45%) were categorized as local anomalies, and 17 (55%) as general anomalies. The ticks were taxonomically identified into 14 species of Amblyomma, and one species of Rhipicephalus. Local anomalies included malformations of scutum/alloscutum, ectromely, leg atrophy, and a third ectopic spiracular plate. General anomalies included opisthosoma duplication, no expansion of dorsal alloscutum in engorged females, and gynandromorphism; the latter is described for 13 tick specimens. Morphological anomalies in Amblyomma aureolatum, Amblyomma brasiliense, Amblyomma humerale and Amblyomma longirostre are reported for the first time. Although the results herein expand the list of anomalous tick species in the Neotropics, future studies should be conducted to clarify the origin of these anomalies.

Abstract Information on the altitudinal distribution of the hard ticks Amblyomma aureolatum and Amblyomma ovale in Brazil is scarce and mainly limited to occasional records. In this study we report our evaluation of records on the altitudinal distribution of A. aureolatum and A. ovale collected from dogs and humans and directly from the environment (host-questing ticks), based on active or passive procedures. The collections were conducted in rural areas of municipalities in the state of Rio de Janeiro, Brazil between 2013 and 2017. Active procedures consisted of dragging or flagging, visual examination of vegetation and removal of ticks present on the authors’ clothing or on infested dogs. Overall, 222 ticks were collected. The altitudes at the collection sites ranged from 98 to 1220 m a.s.l. We noted a significant difference in the altitudinal distribution of A. aureolatum and A. ovale (Mann–Whitney U-test, U = 518.5, P

Abstract Background Small mammals (rodents and marsupials) have been poorly explored for the occurrence of apicomplexan (genus Hepatozoon and genera of the order Piroplasmorida) and Anaplasmataceae agents in Brazil. Thus, this study investigated the occurrence of Hepatozoon spp., Piroplasmorida, and Anaplasmataceae agents in small mammals in seven forest fragments in Brazil. Methods During 2015–2018, small mammals were captured in six forest fragments in the State of São Paulo (Cerrado and Atlantic Forest biomes) and one fragment in the State of Mato Grosso do Sul (Pantanal biome). Mammal blood, liver, spleen, and lung samples were tested molecularly for the presence of DNA of Hepatozoon, Piroplasmorida, and Anaplasmataceae agents. Results A total of 524 mammals were captured, comprising seven species of marsupials, 14 rodents, two carnivores, and one Cingulata. Four novel haplotypes (1, 2, 3, 4) of Hepatozoon spp. were detected in small mammals from different biomes. In São Paulo state, haplotype 1 was detected in rodents from Cerrado and a transition area of Cerrado and Atlantic Forest biomes, whereas haplotype 2 was detected in rodents from the Atlantic Forest biome. On the other hand, haplotypes 3 and 4 were restricted to rodents and marsupials, respectively, from the Pantanal biome of Mato Grosso do Sul. No host species shared more than one haplotype. Despite these distinct geographical and host associations, our phylogenetic analyses indicated that the four Hepatozoon haplotypes belonged to the same clade that contained nearly all haplotypes previously reported on rodents and marsupials, in addition to several reptile-associated haplotypes from different parts of the world. No mammal samples yielded detectable DNA of Piroplasmorida agents. On the other hand, the Anaplasmataceae-targeted polymerase chain reaction (PCR) assay amplified a sequence 100% identical to the Wolbachia pipientis endosymbiont of the rodent filarid Litomosoides galizai. Conclusions We report a variety of Hepatozoon haplotypes associated with small mammals in three Brazilian biomes: Cerrado, Atlantic Forest, and Pantanal. Through phylogenetic analyses, the Hepatozoon agents grouped in the rodent-marsupial-reptile large clade of Hepatozoon spp. from the world. The detection of a W. pipientis associated with the rodent filarid L. galizai indicates that the rodent was infected by filarial nematodes. Graphical Abstract

Considering the formalism of symplectic quantum mechanics, we investigate a two-dimensional nonrelativistic strong interacting system, describing a bound heavy quark-antiquark state. The potential has a linear component that is analyzed in the context of generalized fractional derivatives. For this purpose, the Schrödinger equation in phase space is solved with the linear potential. The ground state solution is obtained and analyzed through the Wigner function for the meson cc¯. One basic and fundamental result is that the fractional quantum phase-space analysis gives rise to the confinement of quarks in the meson, consistent with experimental results.

ABSTRACT: Inadequate exposure of the female reproductive system to steroids in uterine developmental periods can partially inhibit the development of endometrial glands in dogs. However, the effects of steroids on the formed glands functionality remain unknown, as well as the possible occurrence of endometrial fibrosis. This study aimed to evaluate the secretory activity of endometrial glands in prebubertal female dogs submitted to a protocol of partial ablation of the uterine adenogenesis. Sixteen females of non-specific breed were distributed into two groups; MPA (n=8), females that received applications of medroxyprogesterone acetate every 3 weeks; and C (n=8) untreated control females. Ovariohysterectomy was performed in all animals at the age of 6 months and evaluated the uterine horns by histological and histochemistry exams. The secretion intensity (degrees 1-4) was evaluated using periodic acid-Schiff (PAS) and alcian blue (AB) pH 2.5. Histological evaluation was performed using Masson’s trichrome and toluidine blue. Only degree 1 and 2 marks for PAS were observed in both groups, with no difference of uterine secretion intensity between the groups regarding the degrees found. However, the MPA group revealed higher intensity of uterine secretion compared to group C (p

We conducted a molecular survey for Borrelia spp. in Ornithodoros ticks previously reported as biting humans. We collected specimens in natural ecosystems and inside human dwellings in 6 states in Brazil. Phylogenetic analyses unveiled the occurrence of 4 putatively new species of relapsing fever group borreliae.

Abstract Background Rickettsia parkeri strain Atlantic rainforest has emerged in Brazil during the last 10 years, with three laboratory-confirmed human cases. While these cases were epidemiologically associated with the tick Amblyomma ovale, in none of them the tick specimens that bit the patients could be identified. Results We report a clinical case of spotted fever rickettsiosis that was acquired in an Atlantic forest area in Bahia state, northeast Brazil. The case was determined to be caused by R. parkeri strain Atlantic rainforest, based on molecular analysis of the crust removed from the tick bite site (inoculation eschar) of the patients’ skin. DNA extracted from the crust yielded partial sequences of three rickettsial genes (gltA, ompA and ompB), which were 99–100% identical to R. parkeri strain Atlantic rainforest. The tick specimen that was attached to patient skin was identified as a female of A. ovale. Conclusions We report the fourth confirmed case of spotted fever rickettsiosis caused by R. parkeri strain Atlantic rainforest, providing to our knowledge for the first time, direct evidence of R. parkeri strain Atlantic rainforest transmission by A. ovale.

Abstract A new concept for the direct measurement of muons in air showers is presented. The concept is based on resistive plate chambers (RPCs), which can directly measure muons with very good space and time resolution. The muon detector is shielded by placing it under another detector able to absorb and measure the electromagnetic component of the showers such as a water-Cherenkov detector, commonly used in air shower arrays. The combination of the two detectors in a single, compact detector unit provides a unique measurement that opens rich possibilities in the study of air showers.

The capybara, Hydrochoerus hydrochaeris, is the largest extant rodent of the world. To better understand the correlation between size and body mass, and biochemical parameters of capybaras from areas with different degrees of anthropization (i.e., different food supplies), we sampled free-ranging capybaras from areas of natural landscapes (NLs) and human-modified landscapes (HMLs) in Brazil. Analyses of biometrical and biochemical parameters of capybaras showed that animals from HMLs were heavier (higher body mass) than those from NL, a condition possibly related to fat deposit rather than body length, as indicated by Body Condition Index (BCI) analyses. Biochemical parameters indicated higher serum levels of albumin, creatine kinase, cholesterol, fructosamine and total protein among capybaras from HMLs than from NLs; however, when all adult capybaras were analyzed together only cholesterol and triglycerides were positively correlated with body mass. We propose that the biochemical profile differences between HMLs and NLs are related to the obesity condition of capybaras among HMLs. Considering that heavier animals might live longer and reproduce more often, our results could have important implications in the population dynamics of capybaras among HMLs, where this rodent species is frequently represented by overgrowth populations that generate several levels of conflicts with human beings.

Human activities are changing landscape structure and function globally, affecting wildlife space use, and ultimately increasing human-wildlife conflicts and zoonotic disease spread. Capybaras (Hydrochoerus hydrochaeris) are linked to conflicts in human-modified landscapes (e.g. crop damage, vehicle collision), as well as the spread and amplification of Brazilian spotted fever (BSF), the most human-lethal tick-borne disease in the world. Even though it is essential to understand the link between capybaras, ticks and BSF, many knowledge gaps still exist regarding the effects of human disturbance in capybara space use. Here, we analyzed diurnal and nocturnal habitat selection strategies of capybaras across natural and human-modified landscapes using resource selection functions (RSF). Selection for forested habitats was higher across human-modified landscapes, mainly during day- periods, when compared to natural landscapes. Across natural landscapes, capybaras avoided forests during both day- and night periods. Water was consistently selected across both landscapes, during day- and nighttime. Distance to water was also the most important variable in predicting capybara habitat selection across natural landscapes. Capybaras showed slightly higher preferences for areas near grasses/shrubs across natural landscapes, and distance to grasses/shrubs was the most important variable in predicting capybara habitat selection across human-modified landscapes. Our results demonstrate human-driven variation in habitat selection strategies by capybaras. This behavioral adjustment across human-modified landscapes may be related to increases in A. sculptum density, ultimately affecting BSF.

In this work, we study symplectic unitary representations for the Galilei group. As a consequence a nonlinear Schrödinger equation is derived in phase space. The formalism is based on the noncommutative structure of the star product, and using the group theory approach as a guide a physically consistent theory is constructed in phase space. The state is described by a quasi-probability amplitude that is in association with the Wigner function. With these results, we solve the Gross-Pitaevskii equation in phase space and obtained the Wigner function for the system considered.

BACKGROUND:Brazilian spotted fever (BSF), caused by the bacterium Rickettsia rickettsii, has been associated with the transmission by the tick Amblyomma sculptum, and one of its main hosts, the capybara (Hydrochoerus hydrochaeris). METHODS:During 2015-2019, we captured capybaras and ticks in seven highly anthropic areas of São Paulo state (three endemic and four nonendemic for BSF) and in two natural areas of the Pantanal biome, all with established populations of capybaras. RESULTS:The BSF-endemic areas were characterized by much higher tick burdens on both capybaras and in the environment, when compared to the BSF-nonendemic areas. Only two tick species (A. sculptum and Amblyomma dubitatum) were found in the anthropic areas; however, with a great predominance of A. sculptum (≈90% of all ticks) in the endemic areas, in contrast to a slight predominance of A. dubitatum (≈60%) in the nonendemic areas. Tick species richness was higher in the natural areas, where six species were found, albeit with a predominance of A. sculptum (≈95% of all ticks) and environmental tick burdens much lower than in the anthropic areas. The BSF-endemic areas were characterized by overgrowth populations of A. sculptum that were sustained chiefly by capybaras, and decreased populations of A. dubitatum. In contrast, the BSF-nonendemic areas with landscape similar to the endemic areas differed by having lower tick burdens and a slight predominance of A. dubitatum over A.sculptum, both sustained chiefly by capybaras. While multiple medium- to large-sized mammals have been incriminated as important hosts for A. sculptum in the natural areas, the capybara was the only important host for this tick in the anthropic areas. CONCLUSIONS:The uneven distribution of R. rickettsii infection among A. sculptum populations in highly anthropic areas of São Paulo state could be related to the tick population size and its proportion to sympatric A. dubitatum populations.

A review of bee species used as hosts of mutillid wasps in the Neotropical region is presented. Three new confirmed host records are provided for the mutillid species Hoplomutilla biplagiata Mickel, 1939, Pappognatha limes Mickel, 1939, and Tallium aracati Casal, 1962. Two potential host records are provided for Euspinolia rufula Mickel, 1938 and Lophomutilla inca Fritz and Pagliano, 1993. Additionally, Mutilla hoplitiformis Strand, 1909, is transferred to the genus Darditilla. Correlations between host nesting habits and female mutillid morphology are discussed. Lastly, all known confirmed and potential host records in the Neotropical region are compiled. Keywords: Apidae, Host records, Mutillidae, Parasitoids

ABSTRACT A new coccidian species parasitizing white-necked thrushes Turdus albicollis Vieillot, 1818 is described from the Parque Nacional do Itatiaia, in Southeastern Brazil. Isospora machadoae sp. nov. has oocysts that are sub-spherical, 22.2 × 21.2 µm, with bilayered wall, ~1.3 μm thick. Outer layer is rough with micropyle and micropyle cap. Oocyst residuum is absent, but one or two polar granules are present. Sporocysts are ellipsoidal, 13.3 × 9.7 µm. The Stieda body is flattened to half-moon-shaped and substieda body rounded. Sporocyst residuum is present, composed of scattered spherules of different sizes. Sporozoites are vermiform with a refractile body and a nucleus. These parasitized thrushes had no apparent clinical signs of coccidiosis or high densities of oocysts in feces. This condition may be associated with a specific low pathogenicity of I. machadoae sp. nov. and/or with the conserved habitat of these birds, which ensures the ecological niches and thus the immunocompetence to wildlife.

Abstract Mytella guyanensis, consumed and commercialized in coastal regions of Brazil, is one of several bivalve species of socioeconomic interest for coastal communities. Besides serving as a source of income and subsistence for these communities, it also contributes to their food security as it is a source of proteins and micronutrients. Thus, the reproductive cycle of this species was studied aiming to contribute to food security and its preservation. Samples were collected monthly, between March 2014 and March 2015, in a natural stock (12°38'50”S; 38°51'43”W) in a Marine Reserve (RESEX Bay of Iguape) (community Engenho da Ponte), Bahia, Brazil. Mytella guyanensis is collected by women on site, where the artisanal fishing of this resource is performed without following any specific handling procedure. Also, empirical evidence indicates overexploitation. The specimens collected were measured along the anterior-posterior axis (length), and after macroscopic analysis they were fixed in Davidson solution, processed by routine histology techniques and stained with Harris haematoxylin and eosin (H&E). The macroscopic analysis showed sexual dimorphism, with the male and female gonads presenting a milky-white and orange colour, respectively. A 1:1 sex ratio (M: F) was observed and reproduction of the species was continuous all year round. March, April, July and August were the months with highest values of gamete elimination. We suggest that a M. guyanensis management plan should restrict capture during these months, in order to sustainably regulate exploitation of this food resource in this reserve.

In this study, we describe the viral composition of adult Antricola delacruzi ticks collected in a hot bat cave in the state of Rondônia, Western Amazonia, Brazil. A. delacruzi ticks, are special, compared to many other ticks, in that they feed on both bats (larval blood feeding) and bat guano (nymphal and adult feeding) instead of feeding exclusively on vertebrate hosts (blood feeding). Considering this unique life-cycle it is potentially possible that these ticks can pick up/be infected by viruses not only present in the blood of viremic bats but also by virus shed through the bat guano. The viral metagenomic investigation of adult ticks showed that single-stranded negative-sense RNA viruses were the dominant group of viruses identified in the investigated ticks. Out of these, members of the Nairoviridae family were in clear majority constituting 88% of all viral reads in the data set. Genetic and phylogenetic analyses indicate the presence of several different orthonairoviruses in the investigated ticks with only distant relationship to previously described ones. In addition, identification of viral sequences belonging to Orthomyxoviridae, Iflaviridae, Dicistroviridae, Polycipiviridae, Reoviridae and different unclassified RNA viruses showed the presence of viruses with low sequence similarity to previously described viruses.

OBJETIVOS: Avaliar a resposta clínica após a estratégia de troca entre agentes antifator de necrose tumoral alfa (anti-TNF-alfa) em pacientes com artrite reumatoide (AR). PACIENTES E MÉTODOS: Foram incluídos 99 pacientes com diagnóstico de AR (American College of Rheumatology, 1987), em uso de terapia anti-TNF-alfa, para avaliação da resposta terapêutica após 24 semanas. A estratégia de troca foi feita se, após 12 a 24 semanas, houvesse relato de evento adverso sério (T: toxicidade) ou se não ocorresse redução maior que 0,6 do índice de atividade da doença (DAS28) inicial (RI: resposta inadequada). Nesse último caso, o paciente foi considerado como falência primária (FP). Falência secundária (FS) foi definida se houvesse perda de resposta após melhora inicial. Remissão (DAS28 < 2,6), baixa atividade de doença (2,61 < 3,2) e melhora funcional [aumento > 0,2 do questionário de avaliação da saúde (HAQ) inicial] foram avaliadas por análise de regressão linear. P < 0,05 foi considerado significante. RESULTADOS: A estratégia de troca foi realizada em 39 (39,4%) pacientes, especialmente por FP (24,3%), FS (35,1%) e T (40,5%). A taxa de retenção ao primeiro agente foi de 60,1%, e o tempo médio para a troca foi de 14,2 ± 10,9 meses. Após a troca, houve tendência à queda do DAS28 (4,7 ± 1,4; P = 0,08), mas não do HAQ (1,2 ± 0,77; P = 0,11). Cerca de 43% deles alcançaram boa/moderada resposta EULAR. O principal determinante da troca foi o DAS28 inicial mais elevado, independente de idade, tempo de doença e capacidade funcional. CONCLUSÃO: A estratégia de troca entre agentes anti-TNF-alfa é válida para o controle da atividade de doença, embora com baixa probabilidade de remissão e sem melhora significativa da capacidade funcionalOBJECTIVES: To assess clinical response after switching between anti-tumor necrosis factor-alpha (anti-TNF-alpha) agents in patients with rheumatoid arthritis (RA). PATIENTS AND METHODS: This study included 99 patients diagnosed with RA American College of Rheumatology, 1987), on anti-TNF-alpha therapy, to assess the therapeutic response after 24 weeks. Switching was performed if, after 12 to 24 weeks, a severe adverse event was reported (toxicity: T) or if no reduction greater than 0.6 in the initial Disease Activity Score 28 (DAS28) occurred (inadequate response: IR). In case of IR, the patient was considered as primary failure (PF). Secondary failure (SF) was defined as loss of response after initial improvement. Remission (DAS28 < 2.6), low disease activity (between 2.61 and 3.2), and functional improvement [increase in the initial Health Assessment Questionnaire (HAQ) > 0.2] were assessed by use of linear regression analysis. The significance level adopted was P < 0.05. RESULTS: Switching was performed in 39 (39.4%) patients, especially due to PF (24.3%), SF (35.1%) and T (40.5%). The retention rate of the first agent was 60.1%, and the mean time for switching was 14.2 ± 10.9 months. After switching, a tendency towards a decrease in DAS28 was observed (4.7 ± 1.4; P = 0.08), but not in the HAQ (1.2 ± 0.77; P = 0.11). Around 43% of the patients achieved good/moderate EULAR response. The major determinant of switching was a higher initial DAS28, independent of age, duration of disease, and functional capacity. CONCLUSION: Switching between anti-TNF-alpha agents is a valid strategy to control disease activity, despite the low likelihood of remission and no significant improvement in functional capacity

In recent years some coccidian parasites of birds were recorded in Marambaia Island, which is a protected environment with a great biodiversity of birds, mainly tanagers. In this current study Isospora tiesangui, I. sepetibensis, I. ramphoceli, I. navarroi, I. cadimi and I. marambaiensis were identified according to their respective thraupid hosts of the Marambaia Island. These species were characterized with histograms, linear regression and analysis of variance (ANOVA). The main feature of identification was the morphology of the sporocyst, mainly Stieda and substieda bodies, since the morphometry did not provide sufficient differentiation. Besides, Dacnis cayana and Thraupis palmarum were reported as new hosts to I. sepetibensis and I. navarroi respectively.

Os óleos essenciais das folhas e galhos finos de Piper reticulatum e de P. crassinervium, coletados na região norte do Brasil, foram obtidos por arraste à vapor e analisados através de GC/MS. O óleo de P. reticulatum é constituido principalmente por β-elemeno (24,6%) e β-cariofileno (16,7%). Os principais compostos identificados no óleo de P. crassinervium foramβ-cariofileno (17,7%), γ-elemeno (14,4%) e β-elemeno (10,9%).

Embora não esteja definitivamente comprovada que a severidade da malária esteja associada com o vírus da imunodeficiência humana (HIV), sabe-se que a infecção pelo Plasmodium falciparum pode favorecer uma rápida evolução da infecção pelo HIV. Além disso a associação da malária com HIV/AIDS, do ponto de vista clínico, pode ser extremamente grave face a ocorrência de outros microorganismos e/ou neoplasias, o que piora a evolução e prognóstico dos pacientes. A concomitância do vírus HIV com o Plasmodium em zonas endêmicas de malária, é uma possibilidade que deve ser sempre pensada, visto que a sua transmissão está relacionada a fatores de risco ligados aos comportamentos das pessoas, que nem sempre são logo revelados e/ou identificados. Os autores descrevem um caso de malária cerebral por Plasmodium vivaxe Plasmodiumfalciparum em um paciente com AIDS. Descrevem sua evolução clínica e terapêutica.Although it has not been definitely proven that the severity of malaria is associated to human immunodeficiency virus (HIV) we know that infection through Plasmodium falciparum can favor a rapid evolution of the HIV infection. Besides, association of malaria with HIV/AIDS from a clinical point of view can be clinically severe in the face of the occurrence of other microorganisms or neoplasias, which worsens the evolution and prognosis of the affected patients. The concurrence of HIV with Plasmodium in malaria endemic zones is a possibility which should always be taken into consideration, since transmission is related to risk factors caused by people's behavior which are not always promptly revealed and/or identified. The authors report one case of brain malaria infection by Plasmodium vivax and Plasmodium falciparum in a patient with AIDS. They describe the clinical evolution and therapy.

Foram estudados 50 pacientes com AIDS. Todos estes pacientes apresentavam anticorpos anti-HIV1 (ELISA) e preenchiam os critérios de pontuação OPAS/Caracas de definição de casos de AIDS em adultos. A análise do liquido cefalorraqueano (LCR) incluiu: pressão; citologia (número de células e aspectos citomorfológicos); proteína total e eletroforese; concentrações de glicose, cloretos e testes imunológicos para sífilis, toxoplasmose e infecções virais (citomegalovírus, varicela-zoster, Herpes simplex, e HI VI). Investigações bacteriológicas e micológicas (pesquisa direta e cultura), além de teste de aglutinação (látex) para Cryptococcus foram também realizados. Os testes imunológicos usados foram fixação do complemento, imunofluorescência indireta, hemaglutinação passiva e/ou ELISA. Todos os LCR foram analisados no mesmo laboratório seguindo sempre a mesma metodologia. O LCR esteve alterado em 45 pacientes (90,0%) dos 50 pacientes estudados. As principais alterações encontradas no LCR foram: aumento de gamaglobulina em 25 casos (55,5%); aumento da proteína total em 23 (51,1%); hipercitose em 22 (48,9%) e diminuição dos cloretos em 18(40,0%). A detecção de anticorpos anti- HIV1 estiveram presentes em 42 pacientes (93,3%). Toxoplasmose isolada ou associada a outros agentes foi a infecção oportunista mais freqüente, detectada em 26 casos (57,7%). O LCR deverá ser sempre analisado em todos os pacientes com AIDS, com ou sem sintomas neurológicos.Fifty AIDS patients were studied. AH patients had anti-HIV antibodies (ELISA) present and met OPAS/ Caracas punctuation criteria for AIDS cases in adults. Cerebrospinal fluid (CSF) analysis included pressure, cytology (number and cytomorphological aspects), total protein and electrophoresis, glucose and chloride concentration. Bacteriological and mycological investigations were performed as well as agglutination tests for Cryptococcus. Complement fixation, indirect immunoflorescence, passive hemagglutination and/or ELISA tests were performed for syphilis, toxoplasmosis, viral and fungal infections. AH CSF analysis were made in the same laboratory following the same methodology. CSF was alterated in 45 cases (90.0%) of the 50 patients studied. The most important alterations observed were: gammaglobulin (55.5%) and total protein (51.1%) increase, hypercytosis (48.9%) and decrease of chloride concentration (40.0%). HIV antibodies were detected in 42 patients (93.3%). Toxomoplamosis, isolated or associated to other agents, was the most frequent opportunistic infection (57.7%). Cerebrospinal fluid should always be examined in AIDS patients with or without neurological symptoms.