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I Villalobos

Publications and source records attributed to I Villalobos.

6 recordsLinked to original sources
PubMed2000

[Stratification of a hyperendemic city in hemorrhagic dengue].

Any effort to control dengue hemorrhagic fever (DHF) faces a number of challenges. Among these are the great environmental heterogeneity of homes and neighborhoods in urban centers where the primary dengue vector, Aedes aegypti, breeds, as well as shortages of resources and of personnel trained in mosquito control. Adequate epidemiological surveillance could serve as a basis to begin to stratify urban communities and identify the areas in them where control efforts should be focused. In this study we stratified Maracay, Venezuela, a city with hyperendemic dengue hemorrhagic fever, using a geographic information system and analyzing the persistence, incidence, and prevalence of dengue, by means of clinical diagnoses reported from 1993 through 1998. Maracay has around one million inhabitants living in some 349 neighborhoods in the six communities that make up the greater Maracay metropolitan area. During that 1993-1998 period the Maracay area reported 10,576 cases of dengue, 2,593 cases of DHF, and 8 deaths. The incidence of DHF was related to the incidence of dengue, the number of inhabitants in an area, and population density. The spatial pattern of dengue incidence was stable over the years that were studied, and significant, positive relationships were found between pairs of years and the incidence of dengue by neighborhood. The persistence of dengue was related directly to monthly incidence by neighborhood. These spatial patterns helped to divide the city into three strata: 68 neighborhoods without apparent dengue, 226 neighborhoods with low persistence and prevalence, and 55 neighborhoods with high persistence and prevalence. We recommend giving the highest priority for control efforts to these 55 neighborhoods, which make up just 35% of the Maracay urban area but had 70% of all the reported dengue cases.

Aedes↗
PubMed1999

Dengue virus structural differences that correlate with pathogenesis.

The understanding of dengue virus pathogenesis has been hampered by the lack of in vitro and in vivo models of disease. The study of viral factors involved in the production of severe dengue, dengue hemorrhagic fever (DHF), versus the more common dengue fever (DF), have been limited to indirect clinical and epidemiologic associations. In an effort to identify viral determinants of DHF, we have developed a method for comparing dengue type 2 genomes (reverse transcriptase PCR in six fragments) directly from patient plasma. Samples for comparison were selected from two previously described dengue type 2 genotypes which had been shown to be the cause of DF or DHF. When full genome sequences of 11 dengue viruses were analyzed, several structural differences were seen consistently between those associated with DF only and those with the potential to cause DHF: a total of six encoded amino acid charge differences were seen in the prM, E, NS4b, and NS5 genes, while sequence differences observed within the 5' nontranslated region (NTR) and 3' NTR were predicted to change RNA secondary structures. We hypothesize that the primary determinants of DHF reside in (i) amino acid 390 of the E protein, which purportedly alters virion binding to host cells; (ii) in the downstream loop (nucleotides 68 to 80) of the 5' NTR, which may be involved in translation initiation; and (iii) in the upstream 300 nucleotides of the 3' NTR, which may regulate viral replication via the formation of replicative intermediates. The significance of four amino acid differences in the nonstructural proteins NS4b and NS5, a presumed transport protein and the viral RNA polymerase, respectively, remains unknown. This new approach to the study of dengue virus genome differences should better reflect the true composition of viral RNA populations in the natural host and permit their association with pathogenesis.

3' Untranslated Regions↗
PubMedDate not supplied

Leukocyturia in women with diabetes and its clinical implications.

BACKGROUND: Urinalysis is one of the most common studies performed on the diabetic patient at every visit. The presence of leukocyturia is relatively common but it is not clear what the attitude of the physician toward this particular finding should be. The main objective of the present study was to investigate the clinical significance of leukocyturia in diabetic women. METHODS: Ninety-eight diabetic women (84.7% type 2) aged 57 +/- 13 years who were being seen at the diabetic out-patient clinic were randomly selected. All patients underwent a clinical and gynecologic examination and a urinalysis. A Papanicolaou smear and a urine culture were also obtained. RESULTS: The overall prevalence of leukocyturia (>5 cells/high power field (hpf)) was 46.5%. Patients with urinary tract infections (UTI) were 7.5 times more likely to have leukocyturia, while a leukocyte count <5cells/hpf predicted the absence of UTI in 96% of the women. In the comparison of patients with and without leukocyturia, we found that proteinuria (p = 0.06) and bacteriuria (p <0.002) were more common in the women with leukocyturia. A significant association with leukorrhea was not demonstrated. The empirical use of antibiotics was 12 times more frequent in the patients with leukocyturia. CONCLUSIONS: A urinary culture should be requested in all diabetic patients with leukocyturia. The possibility of a UTI is remote when leukocyturia is absent.

Adult↗