Detailed assessment of microhabitat suitability for Aedes aegypti (Diptera: Culicidae) in Buenos Aires, Argentina

Little information is available on the ecology of Aedes aegypti Linnaeus at the southern extreme of its distribution (Buenos Aires, Argentina), particularly on microhabitat suitability. The aim of our study was to identify at a detailed scale, microhabitat factors that correlate with the presence of preimaginal stages of the mosquito. In March 2001, we performed a spatial census of all containers located in a 1 ha patch within a cemetery in Buenos Aires City. On a reference map (1:700) we plotted the position of graves and surrounding corridors, the location of containers, the shade projected by each plant between 10:00 and 16:00 h and vegetation cover. We classified vegetation by height, substrate by composition and shadow by level of exposure to sunlight. We performed univariate and multivariate logistic regression analyses with nine constructed independent variables, some of them at scales of 0.5, 1, 2, 3, and 10 m. Of 850 receptacles examined, 101 contained preimaginal stages of Ae. aegypti. Level of exposure to sunlight, type of substratum, vegetation height and distance of containers to vegetation were significantly associated with the presence of breeding sites at the studied scales. Final multivariate models were significant at scales of 2 m (chi(3)2=25.693, p<0.001) and 3m (chi(3)2=26.440, p<0.001), and 65.9 and 66.8% of our data were correctly classified, respectively, for each scale. Our results suggest that sites less exposed to sunlight, with taller and closer vegetation, and in shaded and vegetated neighbourhoods were the most favourable microhabitats for Ae. aegypti breeding.     

Drug-resistance surveillance among newly HIV-1 diagnosed individuals in Buenos Aires, Argentina

OBJECTIVE: Our objective was to estimate primary resistance in an urban setting in a developing country with a long history of antiretroviral delivery and high coverage levels. DESIGN: We carried out a resistance surveillance study according to WHO HIV-Resistance Guidelines. METHODS: Blood samples were collected from 323 drug-naive HIV-1 infected individuals diagnosed at two HIV voluntary counselling and testing centers in Buenos Aires. Viral-load, CD4 cell counts and detuned assays were performed on all samples. The pol gene was sequenced and the resistance profile determined. Phylogenetic analysis was performed by neighbor-joining trees and bootscanning analysis. RESULTS: We found that 12 (4.2%) of the 284 samples sequenced harbored primary resistance mutations, of which K103N, M41L and V108I were most prevalent. Phylogenetic analysis revealed evidence for the transmission of the K103N mutation among the drug-naive population. The proportion of recent infections identified by the detuned assay was 10.1%. CONCLUSIONS: Levels of primary resistance in Buenos Aires are still low, despite a long history of ARV delivery and high coverage levels.     

HIV Knowledge and Beliefs Among Men Who Have Sex With Men (MSM) in Buenos Aires, Argentina

Five hundred men who have sex with men (MSM), recruited through respondent driven sampling in Buenos Aires, Argentina, were interviewed in order to assess knowledge and beliefs about HIV infection. The mean proportion of HIV correct knowledge answers was 62 %; however participants whose sexual partners in the prior year included women (MSM&W) had lower frequencies of correct answers than participants with no women partners. Men with previous HIV testing experience and those who were HIV positive had higher HIV knowledge. In relation to HIV beliefs, less than half of participants responded correctly to each of the scenarios presented. Accurate answers for all items were more likely among those who only have sex with men. Men have basic HIV knowledge but also many misconceptions about transmission and prevention. Furthermore, MSM&W have less information than those who are exclusively MSM, probably related to the fact that information campaigns specifically targeted gay identified men.     

Antibodies to Trypanosoma cruzi among blood donors in Buenos Aires, Argentina.

OBJECTIVES: The aim of this work was to study the prevalence of anti-Trypanosoma cruzi in the blood donor population in Buenos Aires, to compare the relative sensitivity and specificity of the two screening tests used and to confirm the results with a third assay. MATERIAL AND METHODS: Between May 1995 and July 1999, 64,887 blood donor consecutive samples were screened with the following commercial tests: indirect hemagglutination (IHA) (Polychaco, Buenos Aires, Argentina) and enzyme-linked immunosorbent assay (ELISA) (40,222 with Chagatek, Organon Teknika, Buenos Aires, Argentina, and 24,665 with Chagas EIA, Abbott, S?o Paulo, Brazil). Repeatedly reactive samples in one or both tests were analyzed with a third method: dot blot (Bio Chagas, Gador, Buenos Aires, Argentina) or particle agglutination (Serodia, Fujirebio, Tokyo, Japan). Sera that reacted in at least two tests were considered positive. RESULTS: The seroprevalence was 2.66% (1744 samples were reactive for one or both screening tests), and 1.46% (949 samples) were confirmed positive. The ELISAs proved to be more sensitive (relative sensitivity: 99.67-99.71%) whereas 192 samples (0.47%) were IHA false-negatives (relative sensitivity: 79.77%). Relative specificity for EIA was 98.47--99.23% and for IHA 99.85%. CONCLUSIONS: Results suggest the need of performing two screening tests for Chagas disease in blood banks from endemic areas and the importance of a third confirmatory assay to avoid unnecessary medical counseling.     

HTLV-I and HTLV-II Infections in Spain

IgG present in the circulation of newborn infants is predominantly of maternal origin. In cases of severe Rh D alloimmunization, the maternal anti-D antibodies may lead to Rh D-haemolytic disease of the newborn. However, an impaired placental transport of maternal IgG could be associated with the protection of the fetus/newborn against haemolytic disease as shown in this case report.     

Multidrug-resistant tuberculosis outbreak among transvestite sex workers, Buenos Aires, Argentina.

We describe the first outbreak of multidrug-resistant tuberculosis (MDR-TB) that occurred in Argentina among transvestite sex workers, and actions undertaken for its control. In Buenos Aires city, transmission was documented between 2001 and 2004 by conventional and molecular methods in a hotel where transvestites used to reside and work. The source case was traced back to 1998. Six secondary cases were diagnosed and treated. Thirty-two contacts were investigated. The outbreak strain had formerly caused nosocomial transmission in Rosario, a city 300 km from Buenos Aires. Our findings highlight the difficulties controlling MDR-TB in Argentina.     

A seroepidemiological survey of HTLV-I/HTLV-II in selected Belgian populations

A preliminary survey of the prevalence of HTLV-I antibody during 1987 and 1988 in Belgium revealed no positive results among selected blood donors who sided for some length of time in areas where HTLV-I/HTLV-II is endemic (n = 270), in development-aid workers (n = 145), or in missionaries (n = 35) serving in developing countries. Among foreign groups, African students (n = 212), and political refugees (n = 311), HTLV-I/HTLV-II antibodies were detected and confirmed in 3 cases. Limited data from 1987 and 1988 suggest that HTLV-I/HTLV-II poses no major public health problem in Belgium.     

Epidemiological study of influenza virus infections in young adult outpatients from Buenos Aires,Argentina

Background Influenza virus is the most common cause of influenza‐like illness (ILI) in adults. In Argentina, studies on influenza and other respiratory viruses were performed mostly in pediatric populations. Objectives To determine: (1) the frequency of influenza virus and other common respiratory viruses in adult outpatients with ILI, (2) whether the signs and symptoms predict viral etiology, (3) whether viral diagnosis changes clinical management or infection control measures and (4) to characterize the influenza strains circulating in the community. Population and methods Nasal and pharyngeal swabs from adult outpatients with ILI attending the emergency room during the winter seasons of 2004 and 2005 in Argentina were evaluated by immunofluorescence and RT‐PCR. Results Of 151 samples analyzed, 39 (26%) were influenza A positive, 5 (3·3%) influenza B positive and 4 (2·6%) respiratory syncytial virus positive by immunofluorescence. Two samples (1·3%) were human metapneumovirus positive by RT PCR. Cell culture detected six additional influenza viruses and one adenovirus positive sample. The sensitivity of immunofluorescence for influenza compared with culture was 70%. Symptoms did not predict etiology. Conclusions In this study, 40% of the patients with ILI had a specific viral infection and 83% were influenza viruses. Viral detection was necessary to determine the etiology as signs and symptoms were not different between patients with or without viral infection. Viral diagnosis was important to implement infectious control measures. Circulating influenza strains in this study were similar to the correspondent vaccine strains selected for the Southern hemisphere.     

Unusual localization of an hydatid cyst: first reported case in Buenos Aires,Argentina

Hydatidosis is a parasitic infection caused by the tapeworm larva of Echinococcus spp. Its relevance lies in its wide distribution, great number of clinical cases and outstanding morbility. Hydatid infection of the orbit comprises far less than 1% of the total incidence. This is a case of a patient from Argentina complaining of a two-week evolution proptosis of the right eye. A microscopic examination revealed the presence of protoscolices of Echinococcus spp. in the fluid obtained during the surgical proceedings. The patient was treated with oral albendazole. To our knowledge, this is the first case of occular hydatidosis diagnosed in the city of Buenos Aires, Argentina.     

Prevalencia de los trastornos funcionales digestivos entre los adolescentes de Buenos Aires,Argentina

Introduction and aims

The prevalence of functional gastrointestinal disorders (FGIDs) in Argentinean children and adolescents has not yet been studied. Our aim was to determine the prevalence of FGIDs among children and adolescents in Argentina using the Rome III diagnostic criteria.

Factors associated with H. pylori epidemiology in symptomatic children in Buenos Aires, Argentina

1994 as a group 1 carcinogen by the International Agency for Research on Cancer[2]. H pylori acquisition occurs predominantly during early childhood, and its incidence and prevalence is higher in developing than in developed countries[3-5]. Several risk f…     

High prevalence of HTLV-I and HTLV-II among blood donors in Argentina: a South American health concern

After an HTLV-I endemic area was discovered in Jujuy, a northwestern province in Argentina, to detect other possible foci of HTLV-I/II we started in 1997 a multicentric study to estimate the seroprevalence of HTLV-I/II including blood banks from different regions of the country. Out of 123,233 samples from nine different provinces, 68 proved seropositive with a final prevalence of 0.05% (95% CI = 0.0432-0.0704%). The seroprevalence ranged from 0.03 to 0.16% depending on the geographic location. An HTLV-I [odds ratio (OR) 12.7, 95% confidence interval (CI), 3.43-47.60] prevalence significantly greater was found in the northwest (Salta Province) and a nonsignificant but higher prevalence of HTLV-II in the North (Chaco). Two (0.001%) of the seropositive blood donors reported risk factors due to receiving transfusions and 19 (0.01%) were born in HTLV-I/II South American endemic areas. Although Argentina has been considered a nonendemic country for HTLV-I/II, the need for systematic screening for such infection became imperative based on the present study.