High prevalence of malaria infection in Amazonas state, Venezuela

This study was carried out to determine the incidence of malaria in an endemic region of Amazonas State, Venezuela. For this, 200 random samples were collected from symptomatic and asymptomatic individuals from San Fernando de Atabapo and Santa Barbara. Epidemiological factors were related to malaria infection, which was diagnosed by microscopy observation and amplification of the 18S rDNA sequence by PCR. Malaria prevalence in these populations was 28.5%, whilst P. vivax and P. falciparum prevalences were 12 and 17%, respectively. No infection by P. malariae was found. A mixed infection was found on an asymptomatic individual. Prevalence patterns differed between age groups depending on the Plasmodium species. We found that 34.8% of the P. vivax and 15.2% of the P. falciparum infections were asymptomatic. The use of nets was helpful to prevent P. vivax infection, but did not protect against P. falciparum infection. The results suggest the presence of more than one mosquito vector in the area, displaying a differential pattern of infection for each Plasmodium species. There appear to be risk factors associated with malaria infections in some individuals. The population based approach and PCR diagnosis improved the accuracy of the statistical analysis in the study.

Detection of parvovirus B19 infection in formalin-fixed and paraffin-embedded placenta and fetal tissues

Parvovirus B19 infection was first discovered in 1975 and it is implicated in fetal death from hydrops fetalis the world over. Diagnosis is usually made through histological identification of the intranuclear inclusion in placenta and fetal organs. However, these cells may be scarce or uncharacteristic, making definitive diagnosis difficult. We analyzed histologically placentas and fetal organs from 34 cases of non-immune hydrops fetalis, stained with Hematoxylin and Eosin (HE) and submitted to immunohistochemistry and polymerase chain reaction (PCR). Of 34 tissue samples, two (5.9%) presented typical intranuclear inclusion in circulating normoblasts seen in Hematoxylin and Eosin stained sections, confirmed by immunohistochemistry and PCR. However, PCR of fetal organs was negative in one case in which the placenta PCR was positive. We concluded that parvovirus B19 infection frequency is similar to the literature and that immunohistochemistry was the best detection method. It is highly specific and sensitive, preserves the morphology and reveals a larger number of positive cells than does HE with the advantage of showing cytoplasmic and nuclear positivity, making it more reliable. Although PCR is more specific and sensitive in fresh or ideally fixed material it is not so in formalin-fixed paraffin-embedded tissues, frequently the only one available in such cases.

Natural infection of phlebotomines (Diptera: Psychodidae) in a visceral-leishmaniasis focus in Mato Grosso do Sul, Brazil

The main purpose of this study was to investigate natural infection by Leishmania in phlebotomine females in a visceral-leishmaniasis focus in Antonio João county in Mato Grosso do Sul State, Brazil. Between June and October 2003, the digestive tracts of 81 females captured in Aldeia Campestre, Aldeia Marangatu and Povoado Campestre were dissected. The females were separated by species, location, area and date of capture into 13 groups and kept in ethanol 70%. To identify the Leishmania species using the PCR technique, amplifications of the ribosomal-DNA (rDNA) and mini-exon genes were analyzed. Of the 81 specimens, 77 (95%) were Lutzomyia longipalpis, making this the most common species; only one specimen of each of the species Brumptomyia avellari, Evandromyia cortelezzii, Evandromyia lenti and Nyssomyia whitmani was found. Trypanosomatids were identified in eight of the nine groups of Lutzomyia longipalpis (10.39%) one group from Aldeia Campestre, one from Aldeia Marangatu and six from Povoado Campestre; of the eight groups, one from Aldeia Marangatu and another, with promastigotes forms also confirmed by dissection (1.23%) from Povoado Campestre, were identified by PCR as Leishmania chagasi (2.6%). The other groups gave negative results. These findings indicate that there is a high risk of leishmaniasis transmission in this area.

Cross sectional study reveals a high percentage of asymptomatic Plasmodium vivax infection in the Amazon Rio Negro area, Brazil

A parasitological, clinical, serological and molecular cross-sectional study carried out in a highly endemic malaria area of Rio Negro in the Amazon State, Brazil, revealed a high prevalence of asymptomatic Plasmodium vivax infection. A total of 109 persons from 25 families were studied in five villages. Ninety-nine inhabitants (90.8%) had at least one previous episode of malaria. Serology showed 85.7% and 46.9% of positivity when P. falciparum antigens and P. vivax MSP-1, respectively, were used. Twenty blood samples were PCR positive for P. vivax (20.4%) and no P. falciparum infection was evidenced by this technique. No individual presenting positive PCR reaction had clinical malaria during the survey neither in the six months before nor after, confirming that they were cases of asymptomatic infection. Only one 12 year old girl presented a positive thick blood smear for P. vivax. This is the first description of asymptomatic Plasmodium infection in this area studied.

Human infection by Angiostrongylus costaricensis in Venezuela: first report of a confirmed case

A proven case of human infection caused by Angiostrongylus costaricensis is reported for the first time in Venezuela. The patient was a 57-year-old female surgically operated because of signs of peritonitis with a palpable mass at the lower right quadrant of the abdomen. WBC count reported 16,600 cells/mm³, with 46% eosinophils. The tumoral aspect of ileocolic area and peritoneal lymph nodes prompted the resection of a large area of the terminal ileum, cecum, part of the ascending colon and a small part of the jejunum, where a small lesion was found. The pathology showed thickened areas of the intestinal wall with areas of hemorrhage and a perforation of the cecum. Histology showed intense eosinophil infiltration of the whole intestinal wall, granulomas with giant cells and eosinophils. Some of the granuloma surrounded round or oval eggs with content characterized by a large empty area, cells or embryo in the center, and sometimes nematode larvae. A cross section of an adult nematode worm was observed inside a branch of mesenteric artery. The intestinal affected area, the characteristics of the lesions, the presence of eggs in the submucosa with nematode larvae inside, and the observation of a nematode inside a mesenteric artery, makes sufficient criteria for the diagnosis of an infection by Angiostrongylus costaricensis.

Mayaro virus: imported cases of human infection in São Paulo State, Brazil

Mayaro virus (MAYV) is an arbovirus (Togaviridae: Alphavirus) enzootic in tropical South America and maintained in a sylvan cycle involving wild vertebrates and Haemagogus mosquitoes. MAYV cases occur sporadically in persons with a history of recent activities inside or around forests. This paper reports three cases of MAYV fever detected in men infected in Camapuã, MS, Brazil. Serum samples collected at four days and two months after the onset of the symptoms and examined by hemagglutination inhibition test, revealed monotypic seroconversion to MAYV. Isolation of the virus was obtained from one of the samples by inoculation of the first blood samples into newborn mice. A suspension of the infected mouse brain was inoculated into C6/36 cells culture and the virus was identified by indirect immunofluorescent assay with alphavirus polyclonal antibodies. RT-PCR, performed with RNA extracted from the supernatant of C6/36 infected cells in the presence of alphavirus generic primers as well as specific MAYV primers, confirmed these results. The reported cases illustrate the importance of laboratory confirmation in establishing a correct diagnosis. Clinical symptoms are not always indicative of a disease caused by an arbovirus. Also MAYV causes febrile illness, which may be mistaken for dengue.

Difficulties in the diagnosis of HTLV-2 infection in HIV/AIDS patients from Brazil: comparative performances of serologic and molecular assays, and detection of HTLV-2b subtype

The current diagnosis of human T-lymphotropic virus type-2 (HTLV-2) infection is based on the search of specific antibodies; nevertheless, several studies conducted in Brazil pointed deficiencies of the commercially available kits in detecting HTLV-2, mostly in HIV/AIDS patients. This study searched for the presence of HTLV-1 and -2 in 758 HIV/AIDS patients from Londrina, Paraná, Brazil. Serum samples were screened for HTLV-1/2 antibodies using two EIA kits (Vironostika and Murex), and confirmed by WB (HTLV Blot 2.4, Genelabs). The results obtained by EIA disclosed 49 (6.5%) reactive sera: 43 positive by both EIA kits, and six with discordant results. WB confirmed HTLV-1 infection in seven samples (0.9%) and HTLV-2 in 21 sera (2.8%). Negative and indeterminate results were detected in four (0.5%) and 16 (2.1%) sera, respectively. Blood from 47 out of 49 HTLV seroreactive patients were collected and analyzed for the presence of env, LTR and tax genomic segments of HTLVs by PCR. PCR confirmed six cases of HTLV-1 and 37 cases of HTLV-2 infection (14 out of 16 that were found to be WB indeterminate). Restriction analysis of the env PCR products of HTLV-2 disclosed 36 isolates of HTLV-2a/c subtype, and one of HTLV-2b subtype. These results emphasize the need of improving serologic tests for detecting truly HTLV-2 infected patients from Brazil, and confirm the presence of HTLV-2b subtype in the South of this country.

Epidemiologic features of HIV infection in three municipalities of inner Rio de Janeiro State, Brazil

In Brazil relatively little attention is being paid to the study of the features of the spread of the AIDS epidemic towards small cities and rural areas. We report a descriptive study on the epidemiological features of HIV infection among 208 adult patients seen between July 1999 and May 2006 in the municipal HIV/AIDS Programs of three cities of inner Rio de Janeiro State: Saquarema, Santo Antonio de Pádua and Miracema. A portrait of a heterosexual epidemic emerged, with an overall male to female ratio of 1.1. More than 90% were residents of the studied cities, demonstrating a local demand for HIV-related assistance and the importance of municipal HIV/AIDS Programs. Past or current use of snorted cocaine was reported by a quarter of the patients. Older age and male gender were independent predictors of having a diagnosis of AIDS at presentation. The latter is in accordance with a more recent wave of epidemic spread towards female gender. A low frequency of male circumcision, an important determinant of heterosexual HIV transmission, was recorded. Almost 60% of the patients first presented in advanced stages of HIV infection, suggesting the existence of a large pool of undiagnosed cases in the community.

Frequency of toxocara infection in children attended by the health public service of Maringá, south Brazil

The lack of specific laboratorial diagnosis methods and precise symptoms makes the toxocariasis a neglected disease in Public Health Services. This study aims to determine the frequency of Toxocara spp. infection in children attended by the Health Public Service of Hospital Municipal de Maringá, South Brazil. To evaluate the association of epidemiological and clinical data, an observational and cross-section study was carried out. From 14,690 attended children/year aged from seven month to 12 years old, 450 serum samples were randomly collected from September/2004 to September/2005. A questionnaire was used to evaluate epidemiological, clinical and hematological data. An ELISA using Toxocara canis larval excretory-secretory products as antigen detected 130 (28.8%) positive sera, mainly between children from seven month to five years old (p = 0.0016). Significant correlation was observed between positive serology for Toxocara, and frequent playing in sandbox at school or daycare center (p = 0.011) and the presence of a cat at home (p = 0.056). From the families, 50% were dog owners which exposed soil backyards. Eosinophilia (p = 0.776), and signs and symptoms analyzed (fever p = 0.992, pneumonia p = 0.289, cold-like symptoms p = 0.277, cough p = 0.783, gastrointestinal problems p = 0.877, migraine p = 0.979, abdominal pain p = 0.965, joint pain p = 0.686 and skin rash p = 0.105) could not be related to the presence of anti-Toxocara antibodies. Therefore, two asthmatics children showed titles of 1:10,240 and accentuated eosinophilia (p = 0.0001). The authors emphasize the needs of prevention activities.

Performances of HTLV serological tests in diagnosing HTLV infection in high-risk population of São Paulo, Brazil

Testing problems in diagnosing human T-lymphotropic virus (HTLV) infection, mostly HTLV-II, have been documented in HIV/AIDS patients. Since December 1998, the Immunology Department of Instituto Adolfo Lutz (IAL) offers HTLV-I/II serology to Public Health Units that attend HTLV high-risk individuals. Two thousand, three hundred and twelve serum samples: 1,393 from AIDS Reference Centers (Group I), and 919 from HTLV out-patient clinics (Group II) were sent to IAL for HTLV-I/II antibodies detection. The majority of them were screened by two enzyme immunoassays (EIAs), and confirmed by Western Blot (WB 2.4, Genelabs). Seven different EIA kits were employed during the period, and according to WB results, the best performance was obtained by EIAs that contain HTLV-I and HTLV-II viral lysates and rgp21 as antigens. Neither 1st and 2nd, nor 3rd generation EIA kits were 100% sensitive in detecting truly HTLV-I/II reactive samples. HTLV-I and HTLV-II prevalence rates of 3.3% and 2.5% were detected in Group I, and of 9.6% and 3.6% in Group II, respectively. High percentages of HTLV-seroindeterminate WB sera were detected in both Groups. The algorithm testing to be employed in HTLV high-risk population from São Paulo, Brazil, needs the use of two EIA kits of different formats and compounds as screening, and because of high seroindeterminate WB, may be another confirmatory assay.

Seroprevalence of Toxoplasma gondii infection among indian people living in Iauareté, São Gabriel da Cachoeira, Amazonas, Brazil

The goal of this survey was to estimate the seroprevalence of Toxoplasma gondii infection in Iauareté, a multiethnic Indian community in the upper Rio Negro basin. We carried out a cross-sectional survey (n = 260), in order to obtain serum samples and demographic data. The sample was randomly selected, by family conglomerate analysis. Serodiagnosis was performed by an enzyme-linked immunosorbent assay and indirect immunofluorescence. Prevalence of reactivity was 73.5% (191/260), being higher in the older-age groups, reaching 95.7% (44/46) in the group aged 50 years or more. The majority of seropositive subjects had titers equal to or less than 1:64. Seroprevalence was greater in Indians belonging to the Hupda ethnic group (p = 0.03). According to the present survey, Indian people living in Iauareté have a high prevalence of antibodies to T. gondii. Demographic concentration and urbanization within low sanitation and poor hygiene backgrounds, as well as unfiltered water consumption, may be related to the high frequency of T. gondii seroprevalence observed in the studied area.

Influenza virus and proteolytic bacteria co-infection in respiratory tract from individuals presenting respiratory manifestations

A role for proteolytic bacteria in the exacerbation of influenza virus has been shown in natural hosts such as pigs and humans. Four hundred seven samples were collected from the respiratory tract of individuals presenting clinical manifestations, during influenza season (2003-2005) in São Paulo City. The aim of this study was to evaluate the incidence of determined bacteria co-infecting virus in human respiratory tract. Tests, such as bacteriological, immunofluorescence (IF), RT/PCR and hemagglutination (HA) were used for bacterial and viral investigation. Thirty seven (9.09%) positive for influenza virus were screened by IF. The RT/PCR confirmed the presence of influenza virus in these samples. Bacterial and agar casein tests demonstrated that 18 (48.64%) individuals were infected with proteolytic bacteria such as Staphylococcus spp., Streptococcus spp. and Pseudomonas spp. Among these samples, 13 (35.13%) were co-infected with influenza A virus. Influenza type B, co-infecting bacteria were found in five (13.51%) samples. In vitro the S. aureus protease increased the influenza HA titer after contact for 30 min at 25 ºC. Results revealed the occurrence of co-infection with proteolytic bacteria and influenza in the evaluated individuals. This finding corroborates that virus versus bacteria synergism could be able to potentiate respiratory infection, increasing damage to hosts.

Cutaneous infection caused by Corynebacterium pseudodiphtheriticum: a microbiological report

We report here a rare case of cutaneous infection due to Corynebacterium pseudodiphtheriticum. The patient presented to the clinical laboratory with a skin ulcer on his left leg. Gram-stained preparation of the purulent secretion revealed the presence of numerous rod-shaped Gram-positive organisms in the absence of any other species. The organism was grown in pure culture on sheep blood agar and was further identified as C. pseudodiphtheriticum using a commercial identification system (API-Coryne, BioMérieux, France). The infection was successfully treated with ciprofloxacin. This case emphasizes the importance of the clinical microbiology laboratory in correctly identifying Gram-positive organisms obtained in pure culture from skin ulcers.

Clinical and serological evidence of Toxocara infection in school children from Morrope District, Lambayeque, Peru

The aim of this study was to estimate the frequency of human toxocariosis in a child population from Morrope district, Lambayeque, Peru. From October to December 2005, 182 school children (96 male and 86 female) were studied. Blood samples were collected for Toxocara ELISA-IgG test and hematological examination. Additionally, stool samples were collected for coproparasitological examination to check cross reactions. We found frequency of positives in 32.4% (59/182) with a significant higher proportion of positivity in male children (p < 0.00001). 71.2% of the children with positive serology (52 male and seven female), were between five and 10 years old, 77.96% had respiratory symptoms, 61.02% had ocular manifestations, 38.98% had hepatic symptoms, 38.98% had mild or moderate eosinophilia, signs statistically associated with seropositivity. 83.5% of studied population had some intestinal parasite, such as: Blastocystis hominis (53.3%), Giardia lamblia (31.3%), Entamoeba coli (29.1%), Entamoeba histolytica/E. dispar (1.1%), Hymenolepis nana (5.49%), and Ascaris lumbricoides (3.3%), but they had not any association with serology results. The ownership of dogs or/and cats were significantly associated with seropositivity to anti-Toxocara antibodies although the presence of such pets within the house was not. In conclusion, clinical and serological evidence of Toxocara infection exists in the studied population.