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PubMed2000

Amazonian onchocerciasis: parasitological profiles by host-age, sex, and endemicity in southern Venezuela.

This paper describes, for the human onchocerciasis focus of southern Venezuela, the age profiles of Onchocerca volvulus microfilarial (mf) and nodule prevalence, mf intensity, and mf aggregation for the whole examined population (836 Yanomami people) living in 20 villages, and for these communities classified according to endemicity levels (hypoendemic: < or = 20 %; mesoendemic: 21-59 %; hyperendemic: < or = 60 % infected). Mf prevalence and intensity increased with age, particularly in the hyperendemic areas, and there were no marked differences between the sexes. The prevalence of nodules followed the same age pattern. Fifty percent mf prevalence was reached in the 15-19 year age-class when the population was taken as a whole; nearly in the 10 to 14-year-olds for the hyperendemic level, in those aged 20-29 years in mesoendemic areas, and not reached at all in hypoendemic villages. The degree of mf aggregation was measured by the k value of the negative binomial distribution and by the variance to mean ratio (VMR). The relationship between the standard deviation (S.D.) of mf counts and the mean mf density was also explored. These 3 indices (k, VMR, and S.D.) showed a tendency to increase with both mean mf load and host age. Since infection intensity and host age were themselves positively related, it was not possible to draw definite conclusions about age-specific changes of parasite aggregation. There was not a significant decrease of mf intensity after an earlier peak neither was there a shift towards younger ages of the maximum no. of mf/mg reached as the endemicity level increased. These results are discussed in relation to detection of density dependence in the human host, selection of an indicator age-group for rapid epidemiological assessment (REA) methods, and strategies of ivermectin distribution in the Amazonian focus. It is recommended that, for the Amazonian onchocerciasis focus, the indicator group for REA consists of all those aged 15 years and over.

Adolescent↗
PubMed2000

Gyrodactylus poeciliae n. sp. and G. milleri n. sp. (Monogenea: Gyrodactylidae) from Poecilia caucana (Steindachner) in Venezuela.

Two new species of Gyrodactylus are described from the South American live-bearing fish Poecilia caucana from Venezuela. Gyrodactylus poeciliae n. sp. is characterised by conspicuous ventral bar processes and by marginal hooks in which the tips are barely curved. Morphologically, the species resembles G. bullatarudis and G. costaricensis, and its relationship to the former was confirmed by sequencing the Internal Transcribed Spacers (ITS-1 and ITS-2) and the 5.8S ribosomal gene of the ribosomal DNA. Gyrodactylus milleri n. sp. was characterised by large, sharply angled marginal hook sickles in which the tips overhang the toes. This species resembled most closely G. turnbulli from guppies. These descriptions confirm the occurrence of G. turnbulli and G. bullatarudis-like gyrodactylids on a range of South American poeciliid fishes.

Animals↗
PubMed2003

Bisbalia vossi n. g., n. sp. (Nematoda: Onchocercidae), a filarial worm from a geomyoid rodent, Heteromys anomalus, in Venezuela.

Bisbalia vossi n. g., n. sp. is described from Heteromys anomalus (Rodentia: Geomyoidea: Heteromyidae) in northern Venezuela (Aragua). The filariae were found in a membranous pocket in the pleural cavity, and almost all had ingested red blood cells of their host. The morphology of this onchocercine species is highly evolved (advanced reduction of head and caudal papillae; short undivided oesophagus). Its very short microfilariae (60 microm) and the shape of the tail of the female (two terminal median pairs of bosses) suggest that this species could be derived from Ackertia Vaz, 1934, a South American genus parasitic in caviomorph rodents which is related to the Dipetalonema-line, but Ackertia has several pairs of precloacal papillae, which are absent in the new genus. In North America, where the geomyoid rodents originated and diversified, the two previously described filarial species differ from this new material and show affinities with Old World bat parasites (Litomosa van Beneden, 1871).

Animals↗
PubMed2004

Epidemiological survey of histoplasmine and paracoccidioidine skin reactivity in an agricultural area in Bolívar state, Venezuela.

Paracoccidiodomycosis and histoplasmosis are endemic diseases in the south of Venezuela, representing a public health problem. Prevalence of Paracoccidiodes brasiliensis and Histoplasma capsulatum infections were estimated in Monte Ralo, a rural community area of Bolivar state using paracoccidiodine and histoplasmine skin tests. Paracoccidiodine was intradermically injected to 173 persons and readings were made at 24 and 48 h afterwards to 167 persons (97.85%). Reaction was positive in 8.5% (n = 14) at 24 h post-injection and 13.2% (n = 20) at 48 h. Farmers showed the higher percentage of positivity at 24 and 48 h. One hundred-seventy five persons were intradermically injected with histoplasmine but 167 and 157 of them attended for reading of the dermal reaction at 24 and 48 h post-injection respectively. Tests were positive in 25.7% (n = 43) at 24 h and 42.7% (n = 67) at 48 h. Further studies are needed in surrounding places to delimit the endemic area of these mycosis in the Bolivar state. However, epidemiological vigilance of PCM and H should be considered by local health authorities.

Adolescent↗
PubMed1994

Case-control study of gastric cancer screening in Venezuela.

A screening programme for early gastric cancer was introduced in the state of Tachira, Venezuela, in 1980. Screening was performed by photofluorography, using two mobile units. The efficacy of this programme in reducing mortality from stomach cancer was evaluated by means of a case-control study. Cases were 241 individuals who died from stomach cancer in the period 1985-89. Ten live controls per case were drawn from the electoral rolls, matched by sex, age and residence. Exposure to the screening examination of cases and controls was assessed through individual linkage with the programme's centralised database. After the exclusion of examinations occurring within the 6 months preceding the case's diagnosis, the odds ratio (OR) of dying from stomach cancer for those screened was 1.26 (CI 0.83-1.91) and the OR in females was lower than in males: 0.77 (CI 0.33-1.78) and 1.52 (CI 0.94-2.47) respectively. Odds ratios associated with years since last test and number of tests did not differ significantly from 1. These results show the inefficacy of the programme in reducing mortality from gastric cancer in the area. In an attempt to determine whether this result was due to selection bias, an analysis restricted to subjects who had been screened at least once was performed. When examinations occurring after an index date at various intervals before the case's diagnosis were excluded, the screening test appeared to protect from death, although confidence intervals of the odds ratios are large, for example OR = 0.47 (CI 0.24-0.98) when excluding tests within 1 month.

Age Factors↗
PubMed2001

Mutation of PVRL1 is associated with sporadic, non-syndromic cleft lip/palate in northern Venezuela.

Non-syndromic cleft lip with or without cleft palate (CL/P, MIM 119530) is among the most common of major birth defects. Homozygosity for a nonsense mutation of PVRL1, W185X, results in an autosomal recessive CL/P syndrome on Margarita Island, CLPED1 (ref. 1). Here we demonstrate highly significant association between heterozygosity for this mutation and sporadic, non-syndromic CL/P in northern Venezuela.

Cell Adhesion Molecules↗
PubMed2002

Prevalence of erectile dysfunction in Colombia, Ecuador, and Venezuela: a population-based study (DENSA).

The purpose of this study was to estimate the prevalence of erectile dysfunction (ED) in Colombia, Ecuador, and Venezuela. A 49-item questionnaire was completed by 1946 men aged 40 years and older. The age-adjusted combined prevalence of minimal, moderate, and complete ED for all three countries was 53.4%, with 19.8% of all men reporting moderate to complete ED. Age was the variable most strongly linked to ED; the prevalence of complete ED increased markedly in men older than 79 y of age (31.9%) and 70-79 y (17.2%) compared with men aged 40-49 y (<3%). Several medical conditions, such as hypertension, benign prostatic hyperplasia, and diabetes, and the use of medications to treat these conditions were correlated with the prevalence of ED. This study corroborates earlier studies demonstrating that ED is very common, increases dramatically with age, and has multiple correlates, including some that are also risk factors for cardiovascular disease.

Adult↗
PubMed2002

Efficacy and safety of oral sildenafil citrate (Viagra) in the treatment of male erectile dysfunction in Colombia, Ecuador, and Venezuela: a double-blind, multicenter, placebo-controlled study.

The objective of this work was to assess the efficacy and safety of sildenafil in patients with erectile dysfunction (ED) from Colombia, Ecuador, and Venezuela. One hundred and fifty-eight outpatients with ED participated in a double-blind, flexible-dose, randomized-controlled trial. Efficacy measures included question 3 (achieving an erection) and question 4 (maintaining an erection) from the International Index of Erectile Function (IIEF), the five functional domains of the IIEF, a global efficacy question, and patient event log. Sildenafil increased patients' ability to achieve/maintain erections (P<0.01). Seventy-seven per cent of sildenafil- vs 46% of placebo-treated patients reported improved erections (P<0.001). Sixty-five percent and 35% of intercourse attempts were successful among sildenafil and placebo patients, respectively (P<0.05). Sildenafil patients showed significant improvements in three of the five IIEF functional domains (P<0.05). Adverse events were reported for 51% and 33% of sildenafil and placebo patients, respectively. It can be concluded that sildenafil is an effective, well-tolerated treatment for ED in patients from Latin America.

Administration, Oral↗
PubMed2000

Epidemiologic aspects of arterial hypertension in Maracaibo, Venezuela.

The purpose of this study was to determine the prevalence of arterial hypertension (HT) awareness and the influence of age, sex and body mass index on the degree of control of HT in the population of Maracaibo, State of Zulia, Venezuela. It included 7424 subjects, 3640 males (M) and 3784 females (F). Information was collected through domiciliary visits with a questionnaire designed for this purpose. Hypertension was defined as such when values were > or =140 mm Hg for systolic blood pressure (SBP) and > or =90 mm Hg for diastolic blood pressure (DBP). In the total sample, 36.9% were hypertensive. A higher prevalence in M (45.2%) than in F (28.9%), was observed. The percentage of HT increased with age in both genders. There was a high percentage of hypertensives with obesity (73.5%) which did not vary when discriminating for gender and age. Obese subjects were more prone to have HT until age 50. Those younger than 40 took less medication but were proportionally better controlled. Of the hypertensive population 54.3% were not aware of their condition, of 45.7% remaining, 22.8% did not have regular control visits, 18.4% inspite of medication were not controlled and only 4.5% were well controlled. Better control was observed in F (6.2%) than in M (3.3%), P < 0.001. It is concluded that HT is a serious public health problem because of its high prevalence and lack of control, and it is necessary to implement educational and medical programmes for the detection and control of this disease.

Adult↗
PubMed2003

Control trial of Lutzomyia longipalpis s.l. in the Island of Margarita, Venezuela.

The incidence of the American visceral leishmaniasis (AVL) in the Island of Margarita, a major tourist centre in Venezuela, has been increasing between 1998 and 2001. Lutzomyia longipalpis s.l. is the recognized vector, which was found naturally infected with Leishmania spp, indistinguishable from the parasites recovered from dogs and children. In 1999-2000, we conducted a control trial in Santa Ana del Valle and Las Cabreras, which have similar epidemiological and ecological conditions. The trial was based on intradomestic residual spraying of lambda-cyhalothrin, E.C., 25 mg/m2 and spatial fogging of fenitrothion around the houses at 30 g/ha. Sandfly abundance was recorded using Centers for Disease Control (CDC) traps indoors and outdoors. We found significantly reduced sandfly populations in the target locality. Wall bioassays showed that the residual effect of the insecticide lasts for about 3 months. We believe that indoor spraying with lambda-cyhalothrin three times a year, at a dose slightly greater than 25 mg/m2, might reduce the L. longipalpis s.l. population to a level low enough for achieving a significant reduction of the indoor transmission, thus protecting small children from the disease.

Animals↗
PubMed1998

Abundance of Lutzomyia ovallesi but not Lu. gomezi (Diptera: Psychodidae) correlated with cutaneous leishmaniasis incidence in north-central Venezuela.

In north-central Venezuela Lutzomyia gomezi and Lu. ovallesi are the main endophilic/anthropophilic species of phlebotomine sandflies implicated as vectors of cutaneous leishmaniasis (CL). Lutzomyia ovallesi has been found infected with Leishmania braziliensis (1.2%) and less often with Le. mexicana (0.07%), while Le. braziliensis infections have also been found in Lu. gomezi (0.47%). We investigated population densities of these sandflies using two sampling methods with four series of collections between January 1991 and March 1995 at El Ingenio, Miranda State. All-night outdoor collections from a Shannon trap were correlated with indoor collections from CDC light-traps by linear regression, which proved to be statistically significant for both species. Estimated numbers of female sandflies per house per night were found to be proportional to monthly precipitation (i.e. rainfall), with a lag time of seven months for Lu. ovallesi and of six months for Lu. gomezi. Predominance of Lu. ovallesi over Lu. gomezi (c. 10:1) was observed throughout the year, with the number of infected females estimated as 0.043+/-0.047 Lu. ovallesi and 0.0085+/-0.0124 Lu. gomezi per CDC trap per house per night (ratio approximately 5:1). The mean rate of new CL cases per house per year and sandfly abundance were correlated by linear regression, showing a statistically significant relationship for Lu. ovallesi but not for Lu. gomezi. The negative intercept indicated that, on average, the CDC trap density exceeds 800 Lu. ovallesi females/house/year before new CL cases occur at El Ingenio.

Animals↗
PubMed2002

Fine-scale population structure and dispersal in Biomphalaria glabrata, the intermediate snail host of Schistosoma mansoni, in Venezuela.

Biomphalaria glabrata is the main intermediate host of Schistosoma mansoni in America and one of the most intensely studied species of freshwater snails, yet very little is known about its population biology. Here, we used seven highly polymorphic microsatellite loci to analyse genetic diversity in the Valencia lake basin, which represents the core of the endemic area for schistosomiasis in Venezuela. Populations were sampled at short spatial scale (a few kilometres), both inside the lake and in ponds or rivers near the lake. Our results indicate that B. glabrata essentially cross-fertilizes, with little variation in selfing rates among populations. Our markers detected considerable genetic variation, with an average heterozygosity of 0.60. More diversity per population was found within than outside the lake, suggesting an influence of connectivity among populations on the levels of genetic diversity. A marked population structure was detected and lake populations were less structured than other populations. Most individuals were assigned to their population of origin using an assignment test. No strong demographic signal (e.g. bottleneck) was detected, though lake populations are likely to experience bottlenecks more frequently than the other populations analysed. Differences in gene flow therefore seem to play an important role in population differentiation and in the restoring of genetic diversity in demographically unstable populations.

Animals↗
PubMed2003

Intestinal parasitic infection and associated symptoms in children attending day care centres in Trujillo, Venezuela.

OBJECTIVES: To examine the presence of intestinal protozoan and helminth infections and their association with clinical signs and symptoms in children in Trujillo, Venezuela. METHODS: Conventional microscopic methods (thick-smear, saline and iodine solutions) were used to identify parasites in stool samples of 301 children attending day care centres. A subgroup of 45 children was evaluated clinically and parasitologically five times during a 1-month period using conventional methods and the Kinyoun acid-fast stain for Cryptosporidium identification. RESULTS: The point prevalence of protozoan infections was 21% for Giardia duodenalis, 1.0% for Entamoeba histolytica/dispar, 4% for Entamoeba coli, 16% for Blastocystis hominis, and 89% for Cryptosporidium parvum. Prevalence of helminth infection was 11% for Ascaris lumbricoides, 10% for Trichuris trichiura, 0.3% for Strongyloides stercoralis, and 1.3% for Hymenolepis nana. Over a 1-month time frame, new infections were observed at a rate of 11% for G. duodenalis, 4% for E. histolytica/dispar, 7% for A. lumbricoides, 11% for T. trichiura, 0% for S. stercoralis, and 2% for H. nana. Intestinal symptoms (diarrhoea, vomiting, gas, stomach pain, and loss of appetite) were associated with presence of one or more of C. parvum or B. hominis organisms in stool samples. CONCLUSIONS: Intestinal parasitic infections contribute significantly to the enteric disease burden experienced by this group of children. The organisms most strongly implicated by this study are common and difficult-to-treat protozoan pathogens.

Child Day Care Centers↗
PubMed1998

The re-emergence of American visceral leishmaniasis in an old focus in Venezuela: present situation of human and canine infections.

The report of a new autochthonous case of human American Visceral Leishmaniasis (AVL) in 1992 in the village of Guayabita, Aragua State, Venezuela (10 degrees 16'N, 67 degrees 28'W; 500 m asl), led us to undertake an epidemiological study in this locality. A demographic survey was conducted using a structured questionnaire in which data was collected regarding sex, age, occupation, length of residence in the area and migratory history. A leishmanin skin test (LST) was applied and samples of venous blood for counter immunoelectrophoresis (CIEP) and immunofluorescent antibodies (IFAT) tests were drawn. The prevalence of positive LST was 11.4%. The positivity was highest among males and increased with age. Young males seemed to be more exposed to infection than females. Since occupation per se did not seem to account for this association, it may be explained as a gender-associated behavior, leading to different degrees of exposure to sand flies. The canine population was also screened for leishmanial infection. One dog was shown to be parasitologically infected with Leishmania sp. Four out of 71 dogs (5.6%) were positive for FG, CIEP, IFAT and Western Blot and 11 (15.5%) were positive for CIEP. These results suggest that after almost 30 years of epidemiological silence, American visceral leishmaniasis has re-emerged in this focus.

Adolescent↗
PubMed1999

The re-emergence of American visceral leishmaniasis in an old focus in Venezuela. II. Vectors and parasites.

As part of an epidemiological study in an old focus of American Visceral Leishmaniasis (AVL) in Venezuela (Guayabita, Aragua State), a longitudinal entomological survey (January 1993-June 1994) was carried out. A total of 3,239 males and 6,043 females belonging to 11 phlebotomine sandfly species were collected. The two recognised vectors of AVL in the New World, Lutzomyia evansi and Lu. longipalpis were found to be sympatric. Lutzomyia evansi was the dominant species (86.4%), almost ten fold times more abundant than Lu. longipalpis (10.6%). The two species alternated seasonally: Lu evansi peaked at the end of the rainy season while Lu. longipalpis, almost virtually absent during such period, increased in the dry season. This species seems more greatly influenced by the temperature. Seven of 4,559 Lutzomyia evansi (0.15%) and one of 353 Lu. longipalpis (0.28%) were found positive for suprapyloric promastigotes. Using the polymerase chain reaction (PCR) with universal primers, all isolates were identified as Leishmania spp. Two cultures from Lu. evansi, IEVA/VE/93/UCNA-2 and IEVA/VE/93/UCNA-3, were established. k-DNA restriction analysis showed high homologies between these isolates and Leishmania chagasi. High hybridization signal with L. chagasi specific kDNA confirmed these results. These findings suggest that Lu. evansi may play a role as vector of visceral leishmaniasis in this area. The identity of the parasite carried by Lu. longipalpis needs to be confirmed.

Animals↗
PubMed1990

The carriage of Escherichia coli resistant to antimicrobial agents by healthy children in Boston, in Caracas, Venezuela, and in Qin Pu, China.

BACKGROUND AND METHODS: The healthy members of a community represent its largest reservoir of bacteria resistant to antimicrobial agents. We compared the resistance to eight agents of Escherichia coli in stool samples from untreated, healthy children in cities on three continents. RESULTS: When screened by a selective method that detected 1 resistant colony in 10,000 colonies, nearly half the children in Boston (18 of 39) had no resistant colonies--a finding consistent with the findings of other surveys performed in developed countries. However, all but 1 of 41 children screened in Caracas, Venezuela, and all but 2 of 53 in Qin Pu, China, carried resistant strains. Only 1 child in Boston but 25 in Caracas and 34 in Qin Pu carried strains resistant to trimethoprim. None of the children in Boston or Caracas but 17 in Qin Pu carried strains resistant to gentamicin. Among 10 colonies selected randomly from each stool sample, the average frequency of resistance in Caracas was 3.6 times greater than in Boston, and that in Qin Pu was 5.3 times greater. There was resistance to five or more antimicrobial agents in 20 percent of the Qin Pu strains and in 6 percent of the Caracas strains but in none of the Boston strains. CONCLUSIONS: In addition to clinical isolates, as reported previously, the bacteria that colonize health children in the community may be resistant far more often in some regions than in others. A low rate of carriage of antimicrobial resistance in the community should become a public health goal.

Anti-Bacterial Agents↗
PubMed1997

Efficacy of the rhesus rotavirus-based quadrivalent vaccine in infants and young children in Venezuela.

BACKGROUND: Rotaviruses are the principal known etiologic agents of severe diarrhea among infants and young children worldwide. Although a rhesus rotavirus-based quadrivalent vaccine is highly effective in preventing severe diarrhea in developed countries, in developing countries its efficacy has been less impressive. We thus conducted a catchment study in Venezuela to assess the efficacy of the vaccine against dehydrating diarrhea. METHODS: In this randomized, double-blind, placebo-controlled trial, 2207 infants received three oral doses of the quadrivalent rotavirus vaccine (4x10(5) plaque-forming units per dose) or placebo at about two, three, and four months of age. During approximately 19 to 20 months of passive surveillance, episodes of gastroenteritis were evaluated at the hospital. RESULTS: The vaccine was safe, although 15 percent of the vaccinated infants had febrile episodes (rectal temperature, > or =38.1 degrees C) during the six days after the first dose, as compared with 7 percent of the controls (P<0.001). However, the vaccine gave 88 percent protection against severe diarrhea caused by rotavirus and 75 percent protection against dehydration, and produced a 70 percent reduction in hospital admissions. Overall, the efficacy of the vaccine against a first episode of rotavirus diarrhea was 48 percent. Horizontal transmission of vaccine virus was demonstrated in 15 percent of the vaccine recipients and 13 percent of the placebo recipients with rotavirus-positive diarrhea. CONCLUSIONS: In this study in a developing country, the quadrivalent rhesus rotavirus-based vaccine induced a high level of protection against severe diarrheal illness caused by rotavirus.

Antibodies, Viral↗
PubMed1988

The vectoral role of several blackfly species (Diptera: Simuliidae) in relation to human onchocerciasis in the Sierra Parima and Upper Orinoco regions of Venezuela.

Experimental and natural infections with Onchocerca volvulus were studied in several anthropophilic blackfly species present in the endemic area of the Upper Orinoco region of Venezuela. When fed on four different Yanomami volunteers in the Sierra Parima, the total infection rate was 31.4% for Simulium guianense in comparison with 7.5% for S. limbatum. The proportion of ingested microfilariae that entered the thorax during the first 24 hours and completed development to the infective stage was also much lower in the latter than in the former species. There was no larval development of O. volvulus in S. antillarum, but one female harboured in its head six infective larvae of a zoonotic filaria. When S. oyapokense s.l. was fed on an infected volunteer in the Upper Orinoco most flies ingested few microfilariae, and further development reached only the L1 stage. Natural infection and infectivity rates for S. guianense in two localities of the Sierra Parima were 0.2-4.0% and 1.3-10.2%, respectively, more than 50% of the L3 larvae being in the head. The corresponding data for S. oyapockense s.l. in the Upper Orinoco were 0.1-0.5%, although the only L3 larva found did not correspond to O. volvulus. It is suggested that S. guianense is the main vector of onchocerciasis in the Sierra Parima and that S. limbatum could play a secondary role. Simulium oyapockense s.l. replaces them in the Upper Orinoco and may maintain a degree of transmission, but its epidemiological importance remains to be assessed.

Animals↗