Complete nucleotide sequence analysis of a Brazilian dengue virus type 2 strain

In the last decade, dengue fever (DF) in Brazil has been recognized as an important public health problem, and an increasing number of dengue haemorrhagic fever (DHF) cases have been reported since the introduction of dengue virus type 2 (DEN-2) into the country in 1990. In order to analyze the complete genome sequence of a DEN-2 Brazilian strain (BR64022/98), we designed primers to amplify contiguous segments of approximately 500 base pairs across the entire sequence of the viral genome. Twenty fragments amplified by reverse transcriptase-PCR were cloned, and the complete nucleotide and the deduced amino acid sequences were determined. This constitutes the first complete genetic characterization of a DEN-2 strain from Brazil. All amino acid changes differentiating strains related to the Asian/American-Asian genotype were observed in BR64022/98, indicating the Asiatic origin of the strain.

Coexistence of antibodies to tick-borne agents of babesiosis and Lyme borreliosis in patients from Cotia county, State of São Paulo, Brazil

This paper reports a case of coinfection caused by pathogens of Lyme disease and babesiosis in brothers. This was the first case of borreliosis in Brazil, acquired in Cotia County, State of São Paulo, Brazil. Both children had tick bite history, presented erythema migrans, fever, arthralgia, mialgia, and developed positive serology (ELISA and Western-blotting) directed to Borrelia burgdorferi G 39/40 and Babesia bovis antigens, mainly of IgM class antibodies, suggestive of acute disease. Also, high frequencies of antibodies to B. bovis was observed in a group of 59 Brazilian patients with Lyme borreliosis (25.4%), when compared with that obtained in a normal control group (10.2%) (chi-square = 5.6; p < 0.05). Interestingly, both children presented the highest titers for IgM antibodies directed to both infective diseases, among all patients with Lyme borreliosis.

Brazilian Flavivirus phylogeny based on NS5

In this work, a comprehensive phylogenetic study based on 600 base pair nucleotide and on putative 200 amino acid sequences of NS5 was carried out in order to establish genetic relationships among 15 strains of 10 Brazilian flaviviruses: Bussuquara, Cacipacore, dengue type 1, 2 and 4, Iguape, Ilheus, Rocio, Saint Louis encephalitis (SLE), and yellow fever. Phylogenetic trees were created by neighbor-joining and maximum parsimony methods. These trees showed Brazilian flaviviruses grouped into three main branches: yellow fever branch, dengue branch subdivided in types 1, 2 and 4 branches, and Japanese encephalitis virus (JEV) complex branch including SLE virus strains, Cacipacore, Iguape, Rocio, Ilheus and Bussuquara. Viruses transmitted by Aedes mosquitoes, such as dengue and urban yellow fever, that are also the only Flavivirus causing hemorrhagic fevers in Brazil, were grouped in the same cluster. Encephalitis associated viruses, transmitted by Culex mosquitoes such as JEV complex branch including SLE virus strains, Cacipacore, Iguape, Rocio, Ilheus and Bussuquara were also grouped in the same clade.

Bloodstream infections in late-stage acquired immunodeficiency syndrome patients evaluated by a lysis centrifugation system

Opportunistic infections, which affect acquired immunodeficiency syndrome (Aids) patients, are frequently disseminated and may cause bloodstream infections (BSI). The aim of this study was to evaluate the main causes of BSI in Aids patients with advanced stage of the disease, with special emphasis on the identification of fungemia. During a 21 months period, all patients with Aids (CD4 < 200) and febrile syndrome admitted to 3 university hospitals were systematically evaluated. For each patient presenting fever, a pair of blood cultures was collected and processed by using a commercial lysis-centrifugation system. One hundred and eleven patients (75 males) with a mean age of 36 years (median 33 years) and mean CD4 count of 64 cells/ml were included. Among the 111 patients evaluated we documented 54 episodes of BSI, including 46 patients with truly systemic infections and 8 episodes considered as contaminants. BSI were caused by gram-positive bacteria (43%), fungi (20%), gram-negative bacteria (15%), mycobacteria (15%), and mixed flora (7%). The crude mortality rate of our patients was 39%, being 50% for patients with BSI and 31% for the others. In conclusion, BSI are a common related to systemic infections on Aids patients with advanced stage of disease and is associated with a high rate of mortality.

Uncertainties regarding dengue modeling in Rio de Janeiro, Brazil

Dengue fever is currently the most important arthropod-borne viral disease in Brazil. Mathematical modeling of disease dynamics is a very useful tool for the evaluation of control measures. To be used in decision-making, however, a mathematical model must be carefully parameterized and validated with epidemiological and entomological data. In this work, we developed a simple dengue model to answer three questions: (i) which parameters are worth pursuing in the field in order to develop a dengue transmission model for Brazilian cities; (ii) how vector density spatial heterogeneity influences control efforts; (iii) with a degree of uncertainty, what is the invasion potential of dengue virus type 4 (DEN-4) in Rio de Janeiro city. Our model consists of an expression for the basic reproductive number (R0) that incorporates vector density spatial heterogeneity. To deal with the uncertainty regarding parameter values, we parameterized the model using a priori probability density functions covering a range of plausible values for each parameter. Using the Latin Hypercube Sampling procedure, values for the parameters were generated. We conclude that, even in the presence of vector spatial heterogeneity, the two most important entomological parameters to be estimated in the field are the mortality rate and the extrinsic incubation period. The spatial heterogeneity of the vector population increases the risk of epidemics and makes the control strategies more complex. At last, we conclude that Rio de Janeiro is at risk of a DEN-4 invasion. Finally, we stress the point that epidemiologists, mathematicians, and entomologists need to interact more to find better approaches to the measuring and interpretation of the transmission dynamics of arthropod-borne diseases.

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.

The fossil tabanids (Diptera Tabanidae): when they began to appreciate warm blood and when they began transmit diseases?

A discussion of the known fossil tabanids (Diptera Tabanidae) is presented based on fossil evidence. This includes the origin of the hemathophagy in the Brachycera, more specifically for tabanids. Several tabanid species in the extant fauna are vectors for disease-producing organisms that affect humans and animals. Bacteria, viruses, rickettsiae, protozoa, and filarial worms can be transmitted by them, causing such diseases as anthrax, tularemia, anaplasmosis, various forms of trypanosomiasis, Q fever, and filariasis. However, if tabanids are directly responsible for all of these diseases is not consensual and the known fossil evidence is presented here.

Therapy of Venezuelan patients with severe mucocutaneous or early lesions of diffuse cutaneous leishmaniasis with a vaccine containing pasteurized Leishmania promastigotes and bacillus Calmette-Guerin: preliminary report

Severe mucocutaneous (MCL) and diffuse (DCL) forms of American cutaneous leishmaniasis (ACL) are infrequent in Venezuela. Chemotherapy produces only transitory remission in DCL, and occasional treatment failures are observed in MCL. We have evaluated therapy with an experimental vaccine in patients with severe leishmaniasis. Four patients with MCL and 3 with early DCL were treated with monthly intradermal injections of a vaccine containing promastigotes of Leishmania (Viannia) braziliensis killed by pasteurization and viable Bacillus Calmette- Guerin. Clinical and immunological responses were evaluated. Integrity of protein constituents in extracts of pasteurized promastigotes was evaluated by gel electrophoresis. Complete remission of lesions occurred after 5-9 injections in patients with MCL or 7-10 injections in patients with early DCL. DCL patients developed positive skin reactions, average size 18.7 mm. All have been free of active lesions for at least 10 months. Adverse effects of the vaccine were limited to local reactivity to BCG at the injection sites and fever in 2 patients. Extracts of pasteurized and fresh promastigotes did not reveal differences in the integrity of protein components detectable by gel electrophoresis. Immunotherapy with this modified vaccine offers an effective, safe option for the treatment of patients who do not respond to immunotherapy with vaccine containing autoclaved parasites or to chemotherapy .

Larvicidal Activity of essential oils from Brazilian plants against Aedes aegypti L.

Aedes aegypti L. is the major vector of dengue fever, an endemic disease in Brazil. In an effort to find effective and affordable ways to control this mosquito, the larvicidal activities of essential oils from nine plants widely found in the Northeast of Brazil were analyzed by measurement of their LC50. The essential oils were extracted by steam distillation and their chemical composition determined by GL-chromatography coupled to mass spectroscopy. The essential oils from Cymbopogon citratus and Lippia sidoides, reported in the literature to have larvicidal properties against A. aegypti, were used for activity comparison. The results show that Ocimum americanum and Ocimum gratissimum have LC50 of 67 ppm and 60 ppm respectively, compared to 63 ppm for L. sidoides and 69 ppm for C. citratus. These results suggest a potential utilization of the essential oil of these two Ocimum species for the control of A. aegypti.

Subclinical form of the American visceral leishmaniasis

The subclinical form of visceral leishmaniasis (VL) shows nonspecific clinical manifestations, with difficulties being frequently met in its clinical characterization and diagnostic confirmation. Thus, the objective of the present study was to define the clinical-laboratory profile of this clinical form. A cohort study was conducted in the state of Maranhão, Brazil, from January/1998 to December/2000, with monthly follow-up of 784 children aged 0-5 years. Based on the clinical-laboratory parameters reported in the literature, four categories were established, with the children being classified (according to their clinical-evolutive behavior) as asymptomatic (N = 144), as having the subclinical form (N = 33) or the acute form (N = 12) or as subjects "without VL" (N = 595). Multiple discriminant analysis demonstrated that the combination of fever, hepatomegaly, hyperglobulinemia, and increased blood sedimentation rate (BSR) can predict the subclinical form of VL as long as it is not associated with splenomegaly or leukopenia. Subjects with the subclinical form did not show prolonged or intermittent evolution or progression to the acute form of VL. Subclinical cases have a profile differing from the remaining clinical forms of VL, being best characterized by the combination of fever, hepatomegaly, hyperglobulinemia, and increased BSR.

First record of human trichinosis in Chile associated with consumption of wild boar (Sus scrofa)

The first South American case of human trichinosis, resulting from the consumption of roast wild boar (Sus scrofa) is reported in Chile. The patient presented fever, diarrhea, myalgias, facial edema, sub-conjunctival reddening, photophobia, eosinophilia, and elevated glutamic oxalacetic transaminase. The diagnosis was confirmed by two immunoenzymatic tests (ELISA) using somatic and excretion-secretion antigens.

Parvovirus B19 infections in state of Rio de Janeiro, Brasil: 526 sera analyzed by IgM-enzyme-linked immunosorbent assay and polymerase chain reaction

In this study were analyzed 526 sera; the patients aged from two days to 65 years old presenting exanthema, which was the most frequent symptom observed, besides fever, adenomegaly, and arthralgia. These sera were negative by enzyme-linked immunosorbent assay (IgM-ELISA) for either rubella (495), toxoplasma (41), cytomegalovirus (12), measles (40), dengue (56), and they were submitted to nested polymerase chain reaction (PCR) for B19 DNA and commercial IgM-ELISA for B19. In 39 abortion cases, IgM or DNA were not detected, therefore they were not took into account for analysis. Specific DNA and IgM were detected respectively in 71 (14.5%) and IgM in 62 (12.7%) sera from 487 sera analyzed. IgM and DNA were simultaneously detected in 43 (8.8%), while agreement among the results by PCR and IgM-ELISA was observed in 440 (90.4%). The sera were collected from January 1999 to December 2000, most of them in 1999 (325), during winter and spring. The major number of clinical cases was observed in the age group from one to ten years old. IgM or DNA were detected in 23 from 51 municipal districts of the state of Rio de Janeiro, where the samples were collected.

Antibodies to Rickettsia rickettsii, Rickettsia typhi, Coxiella burnetii, Bartonella henselae, Bartonella quintana, and Ehrlichia chaffeensis among healthy population in Minas Gerais, Brazil

Rickettsial diseases except those belonging to spotted fever group rickettsioses are poorly studied in South America particularly in Brazil where few epidemiological reports have been published. We describe a serosurvey for Rickettsia rickettsii, R. typhi, Coxiella burnetii, Bartonella henselae, B. quintana, and Ehrlichia chaffeensis in 437 healthy people from a Brazilian rural community. The serum samples were tested by indirected micro-immunoflourescence technique and a cutoff titer of 1:64 was used. The seroprevalence rates for R. rickettsii, R. typhi, C. burnetii, B. henselae, B. quintana, and E. chaffeensis were respectively 1.6% (7 samples); 1.1% (5 samples); 3.9% (17 samples); 13.7% (60 samples); 12.8% (56 samples), and 10.5% (46 samples). Frequent multiple/cross-reactivity was observed in this study. Age over 40 years old, urban profession, and rural residence were significantly associated with some but not all infections rate. Low seropositivity rates for R. rickettsii, R. typhi, and C. burnetii contrasted with higher rates of seropositivity for B. quintana, B. henselae, and E. chaffeensis. These results show that all tested rickettsial species or antigenically closely related possible exist in this particular region.

Genetic characterization of St. Louis encephalitis virus isolated from human in São Paulo, Brazil

The molecular characterization of SPH253157, a new strain of St. Louis encephalitis virus (SLEV), isolated in 2004 from the first case of human infection recognized in the state of São Paulo, Brazil, is reported. The patient, presenting a febrile illness without neurological involvement, was hospitalized as a probable case of dengue fever. Genomic RNA was isolated from the supernatant of C6/36 cells infected with acute phase-serum specimen of the patient and the envelope gene was amplified by reverse-transcription-polymerase chain reaction. The complete nucleotide sequence of the envelope gene of this isolate was directly sequenced from the amplified products and compared with other Brazilian and American SLEV strains. Phylogenetic analyses were carried out under maximum likelihood criterion with outgroups both included and excluded. Outgroups comprised four flavivirus of the Japanese encephalitis group. Phylogeny also included Bayesian analysis. The results indicated that the new SLEV isolate belongs to lineage III, being closely related to an Argentinean strain recovered from Culex sp. in 1979. It is concluded that there are at least 3 lineages of SLEV in Brazil.

Field evaluation of effectiveness of the BG-Sentinel, a new trap for capturing adult Aedes aegypti (Diptera: Culicidae)

In recent years, the development of new tools to gather field information about vector ecological parameters has increased. This report evaluated the BG-Sentinel Trap (BGS-Trap), a promising new attempt to improve collection of the dengue vector, Aedes aegypti. The efficacy of the BGS-Trap was compared with the CDC backpack aspirator, one of the commonest used methods for capturing adult mosquitoes. BGS-Traps captured significantly more Ae. aegypti males (chi2 = 21.774, df = 1, P < 0.05) and females (chi2 = 56.007, df = 1, P < 0.05) than CDC aspirator during all days of field collection. However, CDC aspirator was significantly more efficient to capture Culex quinquefasciatus males (chi2 = 5.681, df = 1, P < 0.05) and females (chi2 = 6.553, df = 1, P < 0.05). BGS-Traps captured host-seeking females (varying between 68.75 to 89.8%) in detriment of females in other behavioral and physiological stages. BGS-Traps proved to be efficient and can be used for monitoring adult mosquito populations.