A new flux-orientated concept to derive critical levels for ozone to protect vegetation

The current European critical levels for ozone (O3) to protect crops, natural and semi-natural vegetation and forest trees are based on a relative small number of open-top chamber experiments with a very limited number of plant species. Therefore, the working group "Effects of Ozone on Plants" of the Commission on Air Pollution Prevention of the Association of German Engineers and the German Institute of Standardization reanalysed the literature on O3 effects on European plant species published between 1989 and 1999. An exposure-response relationship for wild plant species and agricultural crops could be derived from 30 experiments with more than 30 species and 90 data points; the relationship for conifer and deciduous trees is based on 20 experiments with nine species and 50 data points. From these relationships maximum O3 concentrations for different risk stages are deduced, below which the vegetation type is protected on the basis of the respective criteria. Because it is assumed that the fumigation concentrations reflect the O3 concentrations at the top of the canopy, i.e. the upper surface boundary of the quasi-laminar layer if the micrometeorological big-leaf approach is applied, the application of these maximum O3 concentrations requires the transformation of O3 concentrations measured at a reference height above the canopy to the effective phytotoxic concentrations at the top of the canopy. Thus, the approach described in this paper is a synthesis of the classical concept of toxicology of air pollutants (critical concentrations) and the more toxicological relevant dose concept.

Genetic analysis of leishmania parasites in Ecuador: are Leishmania (Viannia) panamensis and Leishmania (V.) Guyanensis distinct taxa?

In the course of an epidemiologic survey in Ecuador, the following collection of Leishmania stocks was isolated: 28 from patients with clinical signs of leishmaniasis, 2 from sloths, 1 from a dog, and 4 from sand flies. For genetic characterization of these stocks, multilocus enzyme electrophoresis (MLEE) and random amplified polymorphic DNA (RAPD) were used. Twenty six of the 35 stocks were identified as either Leishmania (V.) panamensis or L. (V.) guyanensis, 2 stocks were identified as L. (V.) braziliensis, the 2 stocks from sloths showed specific genotypes, and 5 stocks were characterized as hybrids between L. (V.) braziliensis and L. (V.) guyanensis. These data show that genetic diversity of Leishmania in Ecuador is high and that L. (V.) panamensis/guyanensis is the dominant group in this country. The genetic analysis questioned the distinctness between the two species L.(V.) panamensis and L. (V.) guyanensis, since MLEE and RAPD data did not indicate that L. (V.) panamensis and L. (V.) guyanensis correspond to distinct monophyletic lines. Population genetic analysis performed on the L. (V.) panamensis/guyanensis group favors the hypothesis of a basically clonal population structure.

Evidence for hybridization by multilocus enzyme electrophoresis and random amplified polymorphic DNA between Leishmania braziliensis and Leishmania panamensis/guyanensis in Ecuador

The taxonomic attribution of four Leishmania stocks isolated from humans in Ecuador has been explored by both multilocus enzyme electrophoresis and random amplified polymorphic DNA. For three loci, MLEE results showed patterns suggesting a heterozygous state for a diploid organism, while the corresponding homozygous states are characteristic of the Leishmania panamensis/guyanensis complex and Leishmania braziliensis, respectively. Other enzyme loci showed characters attributable to either the L. panamensis/ guyanensis complex or L. braziliensis. RAPD profiles exhibited for several primers a combination of the Leishmania panamensis/ guyanensis complex and L. braziliensis characters. These data hence suggest that the four stocks are the result of hybridization between L. panamensis/guyanensis and L. braziliensis. MLEE data show that the results cannot be attributed to either mixture of stocks, or an F1 in the framework of a simple Mendelian inheritance.

An outbreak of bartonellosis in Zamora Chinchipe Province in Ecuador

We report an outbreak of human bartonellosis in Zamora Chinchipe Province in Ecuador, which occurred in 1995-1996. Nineteen cases were seen, of which 18 presented with classical oroya fever (fever and profound anaemia) and one with verruga peruana; 11 of the cases (58%) had positive blood films containing Bartonella bacilliformis. The houses of cases and neighbouring controls were visited; blood samples for thin films and cultures were collected from members of each house and a questionnaire was administered to investigate possible risk factors for disease transmission. In none of those sampled was B. bacilliformis bacteriologically demonstrable. All case houses were located in isolated areas at the margin of forest and the presence of dead rodents was reported only in case houses (P < 0.05). We suggest that human bartonellosis is a zoonosis with a natural rodent reservoir and that migrant humans infected in this way may become a temporary reservoir host in populated areas.

The novel cuticular collagen Ovcol-1 of Onchocerca volvulus is preferentially recognized by immunoglobulin G3 from putatively immune individuals

The cDNA sequence encoding an Onchocerca volvulus collagen, Ovcol-1, has been isolated and the corresponding native antigen has been identified. The cDNA encodes an open reading frame of 96 amino acid residues containing an uninterrupted 66-residue Gly-X-Y repeat triple-helical (TH) domain (where X and Y may be any amino acids) flanked by a 26-residue amino non-TH domain and a 4-residue carboxyl non-TH domain. The size (9.7 kDa) and structure of the deduced molecule are unique among previously identified collagen chains. This novel collagen type has been designated "mini-chain collagen." Native Ovcol-1 is aqueous soluble and resolves by sodium dodecyl sulfate-polyacrylamide gel electrophoresis at 14.2 kDa under reducing conditions. Immunoelectron microscopy of adult female O. volvulus localized Ovcol-1 to the cuticles of both the adult worm and uterine microfilaria. A group of individuals from an area in Ecuador where O. volvulus is hyperendemic have been classified as putatively immune (PI) to O. volvulus infection. Analysis of the humoral immune responses to Ovcol-1 demonstrated that immunoglobulin G3 (IgG3) of PI individuals preferentially recognized this antigen in comparison to IgG3 of infected individuals.

Bartonellosis in Zamora Chinchipe province in Ecuador

Human bartonellosis was investigated in the Ecuadorian province of Zamora Chinchipe; 17 cases were identified retrospectively from hospital records over the period 1984-1995, mostly from 6 communities in the provincial district of Zumba. A questionnaire concerning risk factors for disease transmission was administered in these 6 communities. Blood samples were taken from individuals with current febrile illnesses or skin lesions suggestive of bartonellosis. Samples for detection of Bartonella bacilliformis were also taken from all school-age children in communities where historical cases had been identified by questionnaire. No bacteriologically positive case was identified and no evidence of asymptomatic infection was detected. Risk factors for disease transmission, identified by the questionnaire, included the presence of sick or dying chickens and guinea-pigs. It was suggested that bartonellosis is a zoonosis with wild animals, probably rodents, as the reservoir. The widespread use of residual insecticides and the easy availability of antibiotics is likely to have modified the epidemiology of this disease over the last decade.

Cryptic speciation in Lutzomyia (Nyssomyia) trapidoi (Fairchild & Hertig) (Diptera: Psychodidae) detected by multilocus enzyme electrophoresis

Lutzomyia trapidoi is the major vector of cutaneous leishmaniasis in Ecuador. In the framework of an epidemiologic study, female Lu. trapidoi sand flies were captured on human bait in La Tablada and Paraiso Escondido. Some coloration heterogeneity among the specimens caught led us to look for the existence of cryptic species using multilocus enzyme electrophoresis. In 196 specimens studied, five of seven enzyme loci proved to be variable, making it possible to check for departures from panmixia both by Hardy-Weinberg statistics and linkage disequilibrium analysis. Two discrete groups were clearly distinguished, which could be differentiated by the diagnostic locus glycerophosphate dehydrogenase. The two groups occurred in sympatry within each locality. Genetic distances measured between these two groups were consistent with values usually found between distinct species. These results suggest the existence of a least two sibling species in Paraiso Escondido as well as La Tablada. The epidemiologic relevance of these results is discussed.

Resistance to Onchocerca volvulus: differential cellular and humoral responses to a recombinant antigen, OvMBP20/11

Persons putatively immune (PI) to Onchocerca volvulus (Ov) infection were identified in Ecuador on the basis of epidemiologic, clinical, and parasitologic findings. Immune responses of PI subjects to a recombinant onchocercal protein, OvMBP20/11, were determined and compared with those of a comparable infected (INF) group from the same Ov-endemic area. PI subjects had significantly less antibody reactivity to this molecule; however, not all INF subjects had an antibody response. IgG1 and IgG4 were the predominant IgG subclasses induced to this molecule, and the amount of IgG1 produced was the only significant difference between the PI and INF groups. In contrast to the antibody responses, proliferative responses to OvMBP20/11 were significantly higher in PI than in INF subjects. Cytokine analysis of peripheral blood mononuclear cell culture supernatants revealed that INF subjects produced significantly more interleukin-10 in response to OvMBP20/11 than did PI subjects. This antigen induced few other cytokines, and there were no differences between study groups.

Isotype-specific characterization of antibody responses to Onchocerca volvulus in putatively immune individuals

Isotype/subclass-specific antibody responses to adult Onchocerca volvulus extract (OvAg) were assessed by both ELISA and immunoblotting for a group of putatively immune individuals (PIs, n = 29) from a hyperendemic area in Ecuador and for a group of infected individuals (INFs, n = 470) from the same regions. As a group, the PIs have been previously shown to possess lower levels of OvAg specific IgG1, IgG2, IgG3 and IgG4 than INF's but semi-quantitative analysis revealed that the relative proportions of these subclasses differs between the two groups. The IgG of the PI group contained a higher proportion of IgG3 and a lower proportion of IgG4 than the INF group. The frequency distribution of IgG3 responses was similar for the PI and INF groups. The frequency distributions for IgG1, IgG4 and IgE were significantly different between the PI and INF groups. A subgroup of the PIs were identified from frequency distributions and multivariate plots of individual isotype responses as having antibody responses (mainly IgG4) possibly indicative of cryptic infection. High IgE responses were exclusive to INF individuals, and a rare response type of high IgG3 with negligible levels of other isotypes/subclasses was seen only in the PI group. However, the majority of the PIs had negligible responses for all antibody classes. Immunoblots demonstrated no obvious differences in qualitative recognition between the PIs and INFs.

Migration of a novel DQA1* allele (DQA1*0502) from African origin to North and South America

A PCR-based strategy termed DHDA has recently been developed which reveals DQA1 and DQB1 allelic polymorphism through gel retardation following electrophoresis. This HLA-typing strategy improves the efficiency of identifying previously undetected DNA sequence polymorphisms. DHDA has been utilized to perform DQA1 genotypic analysis in non-Caucasian populations and has resulted in the identification of a novel allele, DQA1*0502 (designated by the WHO nomenclature committee). This new allele has been found in Africans and South and North Americans of black racial ancestry and is geographically consistent with the African diaspora during the 15th-19th centuries. DQA1*0502 represents a single C-to-G transversion in codon 59 (exon 2) and results in an amino acid change from proline to arginine. Although MHC genes are highly polymorphic, this DQA1*0502 substitution is unique, as it represents an amino acid change at a position assessed previously to be conserved in the human DQ alpha polypeptides.

Hemerocallis as bioindicator of fluoride pollution in tropical countries

In the frame of an active monitoring study at the Serra do Mar near the industrial pool of Cubatão, Brazil,Hemerocallis was tested for its suitability as bioindicator of airborne fluoride pollution. In a screening experiment with various cultivars comparison of susceptibility, correlation of visible injury and foliar fluoride concentration as well as comparison with exposure ofGladiolus gave best results for theHemerocallis cultivar 'Red Moon'. When exposed simultaneously foliar fluoride accumulation ofHemerocallis showed a highly significant linear correlation with fluoride content ofLolium multiflorum, the 'standardized grass culture' andGladiolus, well-known bioindicator species for fluoride impact. With respect to the extent of foliar injuryHemerocallis was less sensitive thanGladiolus, in terms of accumulation capacity it ranged betweenLolium andGladiolus. In general, the results of the biomonitoring study proved that the Atlantic Forest vegetation in a valley downwind from the Cubatão fertilizer industries is still suffering from severe fluoride pollution.

Heterogeneity of IgG antibody responses to cloned Onchocerca volvulus antigens in microfiladermia positive individuals from Esmeraldas Province, Ecuador

The prevalence of IgG antibodies to three recombinant O. volvulus antigens, OvMBP/10, OvMBP/11 and OvMBP/29 was determined in a group of 94 microfilaria positive (mf+) individuals resident in the hyperendemic onchocercal area of Esmeraldas Province, Ecuador. Clone OvMBP/11 was the antigen most frequently recognized by patients sera followed by OvMBP/10 and OvMBP/29. When a cocktail of the three recombinant antigens was used the proportion of positive sera increased to 100%. Antibody responses to the fusion partner maltose binding protein (MBP) were low in comparison with those to the cloned antigens and no correlation of responses between individual antigens was observed. The relative level of antibody response to each of the clones in the cocktail varied between individuals. The distribution of IgG responses to OvMBP/11 was bimodal and those to OvMBP/29 and OvMBP/10 were positively and negatively skewed, respectively. When the three recombinant antigens were used in combination this variation was minimized and the pattern of responses showed a normal distribution as was also seen to crude O. volvulus antigen. The cocktail of recombinants thus offers excellent diagnostic sensitivity in combination with the parasite specificity demonstrated previously.

A sensitive serodiagnostic test for onchocerciasis using a cocktail of recombinant antigens

A specific serodiagnostic test for onchocerciasis has been a priority objective of the World Health Organization. Fragments of cDNA encoding Onchocerca volvulus antigens selected on the basis of their specificity for this parasite were subcloned into a protein purification and expression system. No individual recombinant antigen showed a high sensitivity in an enzyme-linked immunosorbent assay because of heterogeneity in the response of O. volvulus-infected individuals. However, a cocktail of three recombinant proteins showed 96% sensitivity with 100% specificity, compared with 99% sensitivity and only 59% specificity against a crude O. volvulus extract. The sensitivity of detection of individual antigens varied between sera taken from individuals from different geographic areas infected with O. volvulus, but when used as a cocktail, all but one of the microfilaria-positive individuals from all the geographic areas studied were detected. Recombinant probes provide a practical basis for specific diagnostic tests for helminth infections.

Uptake of chloroquine by Onchocerca volvulus in vivo and in vitro

Patients infected with Onchocerca volvulus in the Cayapa River focus in north-east Ecuador were given 500 mg chloroquine diphosphate (CQ) orally prior to nodulectomy. The concentrations of CQ were determined in parasite fragments and host tissue dissected from the nodules, in skin overlying the nodules, and in plasma at 3, 4, 7, and 24 hours after dosing. Onchocerca volvulus took up CQ rapidly, in some cases accumulating the drug to concentrations of over 600 pmol mg-1 worm tissue by three hours, and maintaining similar concentrations through 24 hours. These amounts were markedly higher than peak concentrations in plasma (3.16 pmol microliters-1) and in host tissues (78 pmol mgm-1) and skin (up to 93 pmol mg-1). In vitro uptake of CQ by females of O. volvulus was greater under alkaline conditions (pH 8.4) than at pH 6.8 and 7.4. Uptake reached equilibrium after one to two hours, with final concentrations being approximately 10 times lower than those reached in vivo. Inhibitory effects of chloroquine and its major metabolite desethylchloroquine on the motility of O. volvulus and other filariae have been observed previously in vitro; whether or not the drug had adverse effects on adult parasites in vivo was not determined in these experiments. However, the results illustrate the accessibility of O. volvulus to blood borne agents in vivo, and the potential importance of pharmacodynamic characteristics in the search for new macrofilaricidal agents.

Concentrations of amocarzine in plasma of 71 Ecuadorian patients of two different races receiving 3 mg/kg b.i.d. and 5 mg/kg o.d. oral postprandial doses for 3 days

The possible influence of sex, race and of postprandial administration conditions (either immediately after the end of meal or one hour later) on the plasma concentrations of amocarzine and its N-oxide metabolite, CGP 13 231, was investigated. 71 Ecuadorian patients (48 males and 23 females) of two different races (Indio and Negro) infected with Onchocerca volvulus participated in the study. The concentrations were measured on day 3 at times 3 and 6 h after postprandial administration in the morning of a treatment with either a dose of 5 mg/kg of amocarzine once daily (12 patients) or 3 mg/kg twice daily (59 patients) for 3 days. The concentrations of unchanged drug and of CGP 13 231 measured after the 5 mg/kg treatment were in the low range of those expected from dose proportionality by the comparison with the 3 mg/kg. After the 3 mg/kg dose, no significant difference in concentration of both compounds were detected between the male and female patients between Indio and Negro patients, between the administration immediately after food intake and one hour later. The only detected difference (P = 0.05) was that between Indio and Negro patients for the concentrations of CGP 13 231 at time 3 h. This difference was not confirmed at time 6 h. Therefore, the administration of amocarzine either immediately or one hour after food intake appeared to produce reproducible absorption conditions which were not influenced by sex and race.

Microfilaricidal effect of amocarzine in skin punch biopsies of patients with onchocerciasis from Latin America

Skin punch biopsies were performed in 54 selected patients with onchocerciasis participating in a clinical trial with amocarzine (CGP 6140) in Ecuador and Guatemala. Skin snipping for counting microfilariae of Onchocerca volvulus was done before treatment (day 0) and day 4 and 8 following start of the therapy which consisted of 3 mg/kg amocarzine postprandially twice daily for three consecutive days. The mean microfilarial skin density has been reduced by 45% on day 4 and 95% on day 8. Skin punch biopsies were taken on day 5, within 1 cm from the snip site on the iliac crest. Histopathologic examination revealed that the vast majority of the microfilariae in the upper as well as in the deeper dermis were degenerated or necrotic, surrounded often (57%) by minute foci of fibrinoid change of the collagen. There was usually slight, less frequently moderate eosinophilic, lympho-plasmocytic and initial histocytic inflammatory reaction in the vicinity. Microfilariae were frequently (69%) found at the dermal-epidermal junction and in the epidermis. Occasionally (7%) intra-epidermal microabscesses were noted. Microfilariae were detected also in the lumen of some dermal lymphatic vessels. Therefore it is concluded that amocarzine showed marked microfilaricidal effects in the skin of patients with onchocerciasis as evidenced histologically by mainly destroyed or moribund microfilariae which induced a mild to moderate inflammatory cell reaction.

Longterm follow-up of onchocerciasis patients in Latin America after treatment and retreatment with amocarzine. Preliminary results

Amocarzine has been reported to have onchocercacidal effects. Four months posttherapy the majority of adult worms were dead or moribund. The effect of skin microfilariae lasted up to one year as reflected by markedly reduced microfilaridermia. Since the duration of the onchocercacidal effect of amocarzine beyond one year was unknown and since such an effect may influence the planning of future control strategies, efforts were made to follow-up the already treated amocarzine patients for a second year. The present study from Latin America showed that various amocarzine drug regimens produced a prolonged reduction of microfilaridermia at the end of the second year following the initial therapy, the best levels were about 7-17% of the initial parasite load in the skin for some three days amocarzine regimens. Such an effect occurring in a transmission area of onchocerciasis in Latin America provides additional, although indirect, evidence of a macrofilaricidal effect of amocarzine. Similar experiences of a prolonged amocarzine effect on skin microfilariae has also been observed in West Africa (Ghana, Mali). Preliminary results of retreatment schedules at the start of the third year post-initial therapy showed that simplified postprandial dose regimen of one or two days were well tolerated. It is premature at the time of this report to judge upon their ultimate efficacy, but they had significantly reduced levels of moderate microfilaridermia.

Onchocercacidal effects of amocarzine (CGP 6140) in Latin America

An open clinical trial of amocarzine was carried out in onchocerciasis patients in Ecuador and Guatemala. Administration after food was more effective than that during fasting. The most effective and best tolerated regimen, 3 mg/kg twice daily after food for 3 days (in 312 patients), killed 73% of 1477 female worms at nodulectomy 4 months after treatment. The mean microfilarial skin count was greatly reduced within a week (6-11% Of day 0 value on day 8) and it remained low at least 6 months (14-18% on day 180). Follow-up of a higher dose 3 day regimen taken while fasting showed microfilaridermia of 7-9% of the day 0 value 2 years after treatment.

Abdominal sparganosis in Ecuador: a case report

Sparganosis, infection with plerocercoids of the pseudophyllidean tapeworm Spirometra, rarely has been described in Ecuador. We report the details of a human case of sparganosis identified serendipitously in the course of an abdominal hernia repair. The parasite was found moving freely upon the external oblique fascia adjacent to the site of a direct abdominal hernia. The organism was recovered intact, photographed while alive and preserved for subsequent detailed morphological studies. The presumed route of entry into this patient was percutaneous, after application of a poultice of snake flesh to the site of a painful abdominal hernia. The literature on sparganosis in South America is reviewed. This is the second case of human sparganosis reported from Ecuador.

[Human sparganosis in Ecuador: report of a case in the province of Esmeraldas]

The second case of human sparganosis in Ecuador is reported in a male patient, of an indigenous tribe Chachi, from the province of Esmeraldas, who presented with a nodule localized in the left scapular region. Upon extirpation, a cestode classified as Spirometra was found, but the species could not be determined.

[Prevalence of Chlamydia trachomatis and Neisseria gonorrhoeae in 3 groups of Ecuadorian women with different sexual behaviors]

In order to examine the relationship between sexual conduct and infection with Chlamydia trachomatis and Neisseria gonorrhoeae (gonococcus), the prevalence of these two microorganisms was studied in three groups of Ecuadorean women with different patterns of sexual behavior: 116 prostitutes, 136 women from Borbón Parish who had numerous sexual partners, and 61 pregnant women who had sexual relations with only one partner. The prevalence of infection from one or both of the agents was 53.4% in the prostitutes (n = 62), 34.5% in the women from Borbón (n = 47), and 1.6% in the pregnant women (n = 1). These results bear out the relationship between sexual behavior and risk of sexually transmitted disease.

Onchodermatitis--correlation between skin disease and parasitic load in an endemic focus in Ecuador

Onchocerciasis is a chronic parasitic infection in which infiltration of the skin by microfilariae has been associated with a number of different pathological changes. This survey compared the prevalence of different forms of skin disease in two villages, one of which was located within the endemic zone for onchocerciasis (Zapallo Grande), in a lowland rain forest area of western Ecuador. The commonest skin diseases in both villages were scabies, pyoderma and pityriasis versicolor. In addition changes closely correlated with the presence of microfilariae in skin snips were found in Zapallo Grande--such as atrophic gluteal changes, and acute and chronic papular dermatitis. The only other skin disease associated with onchocerciasis was widespread tinea corporis due to T. rubrum. The Amerindians in the endemic onchocerciasis area were more likely than Negroes to have generalized atrophic changes of the skin, whereas in the latter group significant numbers of individuals had no obvious skin lesions but large numbers of microfilariae were detected in skin snips. Acute papular dermatitis was common in both groups and in biopsied lesions microfilariae could usually be identified within the epidermis or close to the dermo-epidermal junction. One patient had developed severe reactive onchodermatitis (Sowda). Swabs taken from onchocercal skin lesions showed no evidence of skin surface carriage of Staphylococcus aureus. Changes classically associated with onchocerciasis such as pretibial hypopigmentation (leopard skin) and hanging groin were notably absent in this population.

Nitrate reductase activity of needles of Norway spruce fumigated with different mixtures of ozone, sulfur dioxide, and nitrogen dioxide

Four-year-old spruce clones (Picea abies (L.) Karst.) cultivated in sand and provided with a complete nutrient solution, or a solution deficient in magnesium and calcium, were exposed to the pollutant mixtures SO(2)/NO(2), O(3)/NO(2), and O(3)/SO(2)/NO(2), at realistic concentrations for 32 weeks. Fumigation caused a slight increase of total N contents in current year needles, whereas in one-year-old needles N concentrations did not change. The response of nitrate reductase activity to pollutant stress depended on needle age and nutrient supply, respectively. In one-year-old needles fumigation resulted in a significant inhibition of enzyme activity, particularly in Mg and Ca deficient trees. The combination of all three components proved to be most effective in causing a decrease by 60% compared to the control. In contrast, nitrate reductase activity was stimulated in current year needles, especially by O(3)/NO(2) and O(3)/SO(2)/NO(2). Changes in the activity of nitrate and nitrite reductases are considered as a factor contributing to the high phytotoxic potential of pollutant combinations with NO(2).