Toxicity of formulated glyphosate (glyphos) and cosmo-flux to larval Colombian frogs 1. Laboratory acute toxicity.

The spraying of coca (Erythroxylum coca) with glyphosate in Colombia has raised concerns about possible impacts on amphibians. There are few toxicity data for species other than those from temperate regions, and these have not been generated with the combination of formulated glyphosate (Glyphos) and the adjuvant, Cosmo-Flux (coca mix) as used in coca control in Colombia. In order to characterize toxicity of the spray mixture to frogs from Colombia, Gosner stage-25 tadpoles of Scinax ruber, Dendropophus microcephalus, Hypsiboas crepitans, Rhinella granulosa, Rhinella marina, Rhinella typhonius, Centrolene prosoblepon, and Engystomops pustulosus were exposed to the coca mix at concentrations of glyphosate ranging from 1 to 4.2 mg a.e./L diluted in dechlorinated tap water in glass containers. Cosmo-Flux was added to Glyphos in the proportion of 2.3% v/v, as used in aerial application for coca control. Exposures were for 96 h at 23 +/- 1.5 degrees C with 12:12-h light/dark cycle. Test solutions were renewed every 24 h. Concentrations, measured within the first hour and at 24 and 96 h using enzyme-linked immunosorbent assay (ELISA) (Abraxis, LLC), ranged from 70 to 130% of nominal values. LC50 values ranged from 1200 to 2780 microg glyphosate acid equivalents (a.e.)/L for the 8 species tested. Data suggest that sensitivity to Roundup-type formulations of glyphosate in these species is similar to that observed in other tropical and temperate species. In addition, sensitivity of larval amphibians to Roundup-type formulations spans a relatively narrow range. Finally, toxicity of the mixture as used to spray coca was likely driven by the surfactant in the glyphosate formulation, as the addition of Cosmo-Flux did not enhance toxicity above those reported for Vision = Roundup.

Toxicity of formulated glyphosate (glyphos) and cosmo-flux to larval and juvenile colombian frogs 2. Field and laboratory microcosm acute toxicity.

The spraying of coca (Erythroxylum coca) with glyphosate (coca mixture, a combination of formulated glyphosate, Glyphos, and an adjuvant, Cosmo-Flux) in Colombia has raised concerns about possible impacts on amphibians. Although acute LC50 for 8 species of Colombian frogs ranged from 1.2 to 2.78 mg acid equivalents (a.e.)/L, these exposures were conducted in the laboratory in the absence of sediments and organic matter such as would occur under realistic field conditions. In order to assess the effects of overspray of frog habitat under field conditions, Gosner stage 25 tadpoles of Rhinella granulosa, R. marina, Hypsiboas crepitans, and Scinax ruber were placed in outdoor microcosms made from polyethylene plastic fish ponds (2.07 m in diameter, 37 cm high) in an experimental area in Tolima, Colombia. The bottoms of the microcosms were covered with a 3-cm layer of local soil and they were filled to a depth of 15 cm (above the sediment) with local spring water. After up to 100 tadpoles of each frog species were placed in the microcosms, they were sprayed with the coca mixture at concentrations greater and less than the normal application rate (3.69 kg glyphosate a.e./ha). Mortality at 96 h in the control microcosms was between 0 and 16% and LC50 values were between 8.9 and 10.9 kg glyphosate a.e./ha (equivalent to initial concentrations of 5963 to 7303 microg glyphosate a.e./L). Mortality >LC50 was only observed in the tested species when the application rate was >2-fold the normal application rate. In other experiments, juvenile and adult terrestrial stages of frogs were exposed by direct spraying to a range of concentrations of coca mixture. Juveniles and adults were exposed in plastic food containers (19 x 19 cm). The bottom of the container was filled with moistened soil and leaf litter to a depth of 1 cm and 0.5 cm, respectively. Mortality in the controls was low, from 0 to 10%, and from 0 to 35% at the normal application rate. LC50 values ranged between 4.5 kg a.e./ha and 22.8 kg a.e./ha, 1.5- to 6-fold greater than the normal application rate. Data indicate that, under realistic worst-case exposure conditions, the mixture of Glyphos and Cosmo-Flux as used for control of coca in Colombia exerts a low toxicity to aquatic and terrestrial stages of anurans and that risks to these organisms under field conditions are small.

Biomonitoring of genotoxic risk in agricultural workers from five colombian regions: association to occupational exposure to glyphosate.

In order to assess possible human effects associated with glyphosate formulations used in the Colombian aerial spray program for control of illicit crops, a cytogenetic biomonitoring study was carried out in subjects from five Colombian regions, characterized by different exposure to glyphosate and other pesticides. Women of reproductive age (137 persons 15-49 yr old) and their spouses (137 persons) were interviewed to obtain data on current health status, history, lifestyle, including past and current occupational exposure to pesticides, and factors including those known to be associated with increased frequency of micronuclei (MN). In regions where glyphosate was being sprayed, blood samples were taken prior to spraying (indicative of baseline exposure), 5 d after spraying, and 4 mo after spraying. Lymphocytes were cultured and a cytokinesis-block micronucleus cytome assay was applied to evaluate chromosomal damage and cytotoxicity. Compared with Santa Marta, where organic coffee is grown without pesticides, the baseline frequency of binucleated cells with micronuclei (BNMN) was significantly greater in subjects from the other four regions. The highest frequency of BNMN was in Boyaca, where no aerial eradication spraying of glyphosate was conducted, and in Valle del Cauca, where glyphosate was used for maturation of sugar cane. Region, gender, and older age (> or =35 yr) were the only variables associated with the frequency of BNMN measured before spraying. A significant increase in frequency of BNMN between first and second sampling was observed in Narino, Putumayo, and Valle immediately (<5 d) after spraying. In the post-spray sample, those who reported direct contact with the eradication spray showed a higher quantitative frequency of BNMN compared to those without glyphosate exposure. The increase in frequency of BNMN observed immediately after the glyphosate spraying was not consistent with the rates of application used in the regions and there was no association between self-reported direct contact with eradication sprays and frequency of BNMN. Four months after spraying, a statistically significant decrease in the mean frequency of BNMN compared with the second sampling was observed in Narino, but not in Putumayo and Valle del Cauca. Overall, data suggest that genotoxic damage associated with glyphosate spraying for control of illicit crops as evidenced by MN test is small and appears to be transient. Evidence indicates that the genotoxic risk potentially associated with exposure to glyphosate in the areas where the herbicide is applied for coca and poppy eradication is low.

Down regulation of gastric and intestinal phenotypic expression in Epstein-Barr virus-associated stomach cancers.

AIMS: We have previously demonstrated the importance of gastric and intestinal phenotypic expression for stomach carcinogenesis. In this study, we focused on Epstein-Barr virus (EBV)-associated stomach cancers, with special attention to Cdx2. METHODS AND RESULTS: We evaluated the expression of gastric and intestinal phenotypic markers by immunohistochemistry in 35 EBV-positive [EBV (+)] and 75 EBV-negative [EBV (-)] stomach cancers in Colombia. The lesions were divided phenotypically into gastric (G), gastric-and-intestinal mixed (GI), intestinal (I), and null (N) phenotypes. In the EBV (+) cases, the lesions were divided phenotypically into 9 G (25.7%), 1 GI (2.9%), 3 I (8.6%), and 22 N (62.9%) types. Similarly, the EBV (-) lesions were also classified phenotypically as 15 G (20.0%), 19 GI (25.3%), 24 I (32.0%), and 17 N (22.7%) types. The proportion of N type EBV (+) lesions was higher than for their EBV (-) counterparts (P<0.0001). The expression of Cdx2 and MUC2 was also found to be significantly lower in EBV (+) than in EBV (-) stomach cancers (P=0.0001; P<0.0001). Cdx2 expression in the intestinal metaplastic glands present in non-neoplastic mucosa surrounding EBV (+) lesions was also significantly lower than in EBV (-) tumors (P=0.016) despite no evidence of EBV infection. CONCLUSIONS: EBV (+) stomach cancers are characterized by low expression of intestinal phenotype markers, including Cdx2, and only occasional gastric phenotypic expression.

An ecosystem approach to malaria control in an urban setting.

We conducted a research project aimed at strengthening local government and the community for a sustainable malaria control strategy. The project began with a baseline diagnosis of malaria prevalence, a KAP survey, entomology, and health services delivery, after which an epidemiological study was performed to identify risk factors associated with malaria, thereafter used to plan intervention measures. A program evaluation was conducted five years later. By using an ecosystem approach to reanalyze data, this paper discusses how malaria arises from a complex interaction of cultural, economic, ecological, social, and individual factors. Intervention measures require an intersectorial and transdisciplinary approach that does not exist at the moment. Health sector leadership is limited, and there is no true community participation. Implications for research, including the use of qualitative and quantitative methods, study design, and complexity of data analysis are discussed. Finally, implications for malaria control are discussed, stressing the differences between the ecosystem and integrated disease control approaches.

Risk factors associated with malaria infection in an urban setting.

Incidence of malaria in urban settings is a growing concern in many regions of the world and individual risk factors need to be identified to appropriately adjust control strategies. We carried out a cross-sectional study in 1993/94 in an urban area of the largest port of the Pacific Coast of Colombia, where transmission has had an upward trend over the past 5 years. Prevalence of malaria infection was estimated in areas of the city with the highest incidence of disease, and the association between some characteristics of the population and the risk of malaria infection was assessed. Prevalence of malaria infection was 4.4% among the 1380 studied people and we found that it decreased with older age, and with knowledge of disease and preventive measures directed to elimination of breeding sites. In addition, the infection was positively associated with exposure to the forest (P < 0.05), although most of the cases (57/61, 93%) were likely to have been acquired in the urban area. We also found that individuals receiving antimalarial treatment in the previous month had around twice the risk of being infected as compared with those without treatment. In addition, our results suggest that use of bednets could not be a very effective protective measure in settings such as that of our study, and that environmental interventions may be needed to decrease the risk of infection.

Epidemiologic tools for malaria surveillance in an urban setting of low endemicity along the Colombian Pacific coast.

An evaluation of 3 different methods for malaria diagnosis was carried out in an urban area of low endemicity on the Pacific coast of Colombia. Samples were collected from 833 symptomatic patients at a malaria clinic and examined by the polymerase chain reaction (PCR), quantitative buffy coat (QBC; Becton Dickinson, Franklin Lakes, NJ) method, and the traditional thick blood smear. The prevalence of Plasmodium falciparum malaria was 5.88% by thick blood smear, 7.34% by the QBC method, and 21.87% by PCR. The agreement between microscopists was 99.5%. The agreement between the QBC method and thick blood smear was 96.13% (n = 745). Samples positive by PCR but negative by thick blood smear or conversely negative by PCR and positive by thick blood smear were usually of low-level parasitemias. All 3 methods showed agreement in 76.3% of the samples. Sixty-nine (18.8%) samples were positive by PCR but negative by the other 2 methods. Ten samples were positive by both the QBC method and thick blood smear but negative by PCR; most of them had low-level parasitemias. The use of malaria diagnostic methods for epidemiologic surveillance is discussed.

Factors associated with unjustified Cesarean section in four hospitals in Cali, Colombia.

OBJECTIVE: To describe the factors associated with unjustified Cesarean section. DESIGN: Cross-sectional study. SETTING: Four hospitals providing obstetric services, two that serve patients insured through their employer (contributive regimen) and two that serve privately insured patients, in Cali, Colombia. STUDY PARTICIPANTS: Four hundred and sixteen patients with Cesarean section performed in 1996 because of previous Cesarean section, dystocia, acute fetal distress, breech presentation and maternal choice. Patients with toxemia, diabetes, hypertension and other related diseases were excluded. MAIN OUTCOME MEASURES: Unjustified Cesarean section. RESULTS: Of primary Cesarean sections 81.2% were unjustified. Dystocia was the indication given for unjustified surgeries in 78% of cases. Hospital No. 2 had the highest proportion of unjustified procedures compared to the other three institutions. Patients for whom the procedure had been decided before prelabor and on whom it was performed between 7:00 a.m. and 5:59 p.m. had higher proportions of unjustified procedures.

[Mycobacterial infections in HIV-infected patients in Cali, Colombia]. / Infecciones micobacterianas en pacientes infectados por el virus de la inmunodeficiencia humana en Cali, Colombia.

The prevalence of mycobacterial infections was determined in a sample of 155 individuals infected with human immunodeficiency virus (HIV) who were treated in the Social Security Institute (SSI) of Cali, Colombia. A tuberculin test (2 TU PPD RT23) was used, and the presence of mycobacteria was checked through direct microscopy and culturing blood, urine, feces, and gastric aspirate. When clinically indicated, samples of cerebrospinal fluid, bone marrow, and sputum were also examined and cultivated. The absence of reactivity to tuberculin was significantly more frequent in the patients than in the controls (91.3%, compared to 57.4%; chi 2 = 33, P = 0). The prevalence of tuberculosis was 6.5%, in comparison with 0.04% among a group of HIV-negative ISS members (exact binomial 95% confidence interval: 0.0313% to 0.1154%). Nontuberculous mycobacteria (NTM), present in 43 patients, were significantly more frequent than Mycobacterium tuberculosis (27.7%, versus 6.5%; chi 2 = 24.78, P = 0.000,001), but they caused illness only in some cases. The most common species were those of the M. avium-intracellulare complex. M. avium-intracellulare and M. fortuitum had a total prevalence of 7.1% and were the most-prevalent NTM that caused disease in these patients (4.5%); they were also responsible for three cases of disseminated infection. Clinical disease caused by M. tuberculosis or NTM and complete tuberculin anergy were associated with stage-IV HIV infection and with CD4 lymphocyte counts < or = 400/microL. However, the lack of immunocellular response, shown by limited tuberculin reactivity, was found beginning with the asymptomatic HIV carrier stage. The progressive deterioration of the immune system of HIV-positive patients is the determining factor in the high morbidity and mortality with mycobacteria infections and requires prompt chemoprophylaxis or treatment.

Knowledge, beliefs and practices relevant for malaria control in an endemic urban area of the Colombian Pacific.

Research projects for malaria control must involve communities to elicit strategies to be successful and programs to be sustainable. Therefore, knowledge, beliefs and practices of the population concerned must be taken into account in the design of interventions against malaria transmission. We conducted a KAP study in Buenaventura, a port on the Pacific Coast of Colombia where transmission was on the increase at the beginning of this decade. The purpose of the study was to help in the design and implementation of a primary health care approach for malaria control. Both qualitative and quantitative research methods were used. The focus group technique was applied in five urban and peri-urban communities and a cross sectional survey was conducted on a random sample of 1380 subjects with a structured interview on knowledge, practices and also on demographic and epidemiological aspects. The information obtained by the two methods was comparable on knowledge of symptoms, causes and ways of malaria transmission, and prevention practices like the use of bednets or provision of health services. We discuss the relevance of obtaining this information and analyze the elements that must be taken into account for communities to become more involved in malaria control strategies.

Unstable, low-level transmission of malaria on the Colombian Pacific Coast.

The development of immune responses to malarial infection in inhabitants of endemic areas differs according to the level of exposure to the parasite. Adults living in a region where the level of malaria transmission is low (Colombia) have been shown to exhibit a similar response to each of the three regions of the circumsporozoite protein (the central repeated NANP region, and the flanking N- and C-termini). Conversely, donors exposed to a frequent sporozoite challenge in areas of high malaria transmission (Mali) exhibit antibodies predominantly to the NANP repeated domain. Malaria in the people of Zacarías, a community on the Pacific Coast of Colombia where malaria transmission is low and unstable, was the subject of the present study. Within a 9-year period, a negative correlation between rainfall and documented malaria cases was recorded for this area. Thick smears of blood samples of 319 individuals revealed that 8.5% had malarial infections. As most (67%) of the smear-positive cases were asymptomatic, it seems that, despite the low prevalence of malaria in this area, the establishment of clinical symptoms is attenuated, probably because of the acquisition of premunition. Within this region, the most commonly found Anopheles species (representing 61.1% of the mosquitoes caught) and that giving the highest monthly biting rate (4.0 bites/man) was An. neivai. Most (90%) of the human sera tested possessed antibodies to blood-stage forms of Plasmodium falciparum, and 18% had antibodies to sporozoites. More than half (58%) of the adults had been in contact with hepatitis B virus, 7.2% carried hepatitis B surface antigen, and syphilis was common but no subject was found to be seropositive for HIV. A better understanding of the dynamics of the different elements influencing malaria in areas of low, unstable transmission, such as the one described here, is essential for the design of new malaria-control strategies.

[Transmission of urban malaria in Buenaventrua, Colombia: entomological features]. / Transmisión de la malaria urbana en Buenaventura, Colombia: aspectos entomológicos.

During the past several years, there has been an increase in the cases of urban malaria in Buenaventura, Colombia, from 576 in 1987 to 3296 in 1991 and 2017 in 1992; therefore, an epidemiological study to identify transmission patterns was carried out in this municipality on Colombia's Pacific coast. This paper describes the entomological findings regarding vectors, potential breeding sites and behavior of Anopheles species during the period from June 1993 to May 1994. Of the 469 potential breeding sites identified in the urban area, 28 were positive for anophelines, while in the neighboring rural zone, 20 out of 80 potential breeding sites were positive for the immature forms of Anopheles. Mining excavations, lakes and breeding ponds for fish or shrimp were the places where A. albimanus was more frequently found. For A. nuñeztovari, the breeding sites were rain puddles and ponds for breeding fish or shrimp. A. neivai was also identified in the urban area and larvae were collected from bromeliaceous plants. Both inside and outside the households mosquito collections were carried out, and 90% of the collected mosquitoes were identified as A. albimanus. Of the female A. albimanus 54.8% were parous. This species was found to have peak peridomiciliary activity between 6 p.m. and 10 p.m. The highest biting rate in the peridomiciliary area was 7.1 and was observed during March. It is expected that this entomological information will permit the launching of a strong community participation process and the implementation of control measures in accordance with the entomological findings related to malaria in the urban area of Buenaventura.

Antibody-independent inhibition of Plasmodium falciparum in vitro cultures.

The sera of 100 Colombian individuals of African origin living in a malaria-endemic area of the Pacific coast were studied with regard to their capacity to inhibit Plasmodium falciparum cultures in vitro. Antimalarial antibody levels determined by indirect immunofluorescence were higher in the group of infected individuals than in the noninfected individuals, and inhibitory activity assessed by the inhibition of parasite incorporation of 3H-hypoxanthine in vitro was present in the sera of both the infected and noninfected patients. We believe that the noninfected patients were probably immune. The sera of some of the infected patients had high inhibitory capacities for the P. falciparum FCB-1 isolate. When the inhibitory effects of some of the sera were tested by using four parasite isolates from different regions of the world, striking differences among them were found.