Vector competence for Onchocerca volvulus in the Simulium (Notolepria) exiguum complex: cytoforms or density-dependence?

Although Simulium exiguum Roubaud s.l. is present in all South American onchocerciasis foci, it is a significant vector only in Colombia and Ecuador. This variable vectorial role has been attributed to sibling forms that differ in their ability to allow Onchocerca volvulus larval development and their preferred bloodmeal hosts. Here we evaluate the relationship between parasite availability in human skin and infective larval output measured as (a) number of L3 larvae and (b) proportion of surviving flies with L3s in the Cayapa form of S. exiguum s.l. from Ecuador, taking into account the variation in counts of microfilariae (mf) from 6skin snips/patient. Comparisons with other cytoforms (Aguarico, Bucay and Quevedo, absent in the main Ecuadorean onchocerciasis foci) are made to suggest the relative roles of intrinsic susceptibility or co-adaptation versus density-dependent parasite uptake. A nonlinear (limitation) relationship, characterised by an initial rapid increase in infective larvae with increasing mf skin density was confirmed for the Cayapa cytoform. The proportion of infective Cayapa flies increased and saturated rapidly (reaching 80% for >/= 20mf/mg skin). After adjusting for density dependence, non-Cayapa cytoforms exhibited significantly lower L3 loads and proportions of infective flies for a given mf skin density than Cayapa flies, indicating that the susceptibility of those cytoforms is intrinsically lower than that of the Cayapa cytoform and that the differences observed are not due to density-dependent effects.

Impact of long-term treatment of onchocerciasis with ivermectin in Ecuador: potential for elimination of infection.

BACKGROUND: Onchocerciasis is a leading cause of blindness worldwide, hence elimination of the infection is an important health priority. Community-based treatment programs with ivermectin form the basis of control programs for the disease in Latin America. The long-term administration of ivermectin could eliminate Onchocerca volvulus infection from endemic areas in Latin America. METHODS: A strategy of annual to twice-annual treatments with ivermectin has been used for onchocerciasis in endemic communities in Ecuador for up to 14 years. The impact of ivermectin treatment on ocular morbidity, and O. volvulus infection and transmission was monitored in seven sentinel communities. RESULTS: Over the period 1990-2003, high rates of treatment coverage of the eligible population were maintained in endemic communities (mean 85.2% per treatment round). Ivermectin reduced the prevalence of anterior segment disease of the eye to 0% in sentinel communities and had a major impact on the prevalence and transmission of infection, with possible elimination of infection in some foci. CONCLUSION: The distribution of ivermectin in endemic communities in Ecuador might have eliminated ocular morbidity and significant progress has been made towards elimination of the infection. A strategy of more frequent treatments with ivermectin may be required in communities where the infection persists to achieve the objective of elimination of the infection from Ecuador. The elimination of the infection from an endemic country in Latin America would be a major public health achievement and could stimulate the implementation of elimination strategies in other endemic countries.

The effects of long-term community level treatment with ivermectin (Mectizan) on adult Onchocerca volvulus in Latin America.

The objective of this study was to examine nodules from Mexico, Guatemala, and Ecuador collected over a one-year period (2001) to determine the effects of semi-annual ivermectin treatments on Onchocerca volvulus macrofilarial populations. Nodules were sectioned, stained with hematoxylin and eosin, and histologic findings were compared between countries and with historical data prior to the introduction of ivermectin into the region. Nodules from Ecuador had 10 times more dead or moribund worms than the historical control (66.6% versus 6.5%); nodules from patients from Mexico and Guatemala did not differ from the control. More than 80% of the female worms in each country were uninseminated and producing unfertilized oocytes. Nodules containing males differed in each country from the historical control (P < 0.0001), with presence of males ranging from 19.7% in Mexico to 13.6% in Ecuador versus 73% in the control. Nodules with females producing active microfilariae ranged from 7.8% (Mexico) to 2.7% (Ecuador) versus 60% in the historical control (P < 0.0001). Nodules from Ecuador and Mexico were significantly smaller in size than those from Guatemala or historical controls (P < 0.0005). These results depict a deteriorating condition of adult O. volvulus populations in Mexico, Guatemala and Ecuador, indicating that semi-annual ivermectin treatment of >/=6 years has had a profound effect on survival and reproduction of this species.

Human infection by Fasciola hepatica in Venezuela: report of a geriatric case.

A new case of human infection due to Fasciola hepatica is reported in the Venezuelan parasitological literature. The patient is an 81-year-old female asymptomatic, with an eosinophilia of 21% and critrosedimentation rate of 26 mm/h and was found during a routine check up. These values were normal at the time of treatment (4 months later), as were several tests of hepatic function, blood chemistry and peripheral blood haematological values. The number of eggs of the parasite were between 90 and 130/g of facees. The patient was successfully treated with the human formulation of trielabendazole at 2 single doses of 10 mg/kg, each separated by 24 h. The same laboratory tests mentioned above did not show modifications, except for a slight increase in the cosinophil counts at 2 and 11 days and erythrosedimentation rate at 11 days post-treatment. Coproparasitological observations carried out at 12, 18, 60 and 120 days post-treatment were negative. No clinical symptoms were registered up to 2 months after treatment. The patient most probably acquired the infection at home through the ingestion of commercially available lettuce from an endemic area of bovine fascioliasis, very distant from home, and between 4 and 7 months previous to treatment. We stress the need to investigate F. hepatica infections which he been neglected, probably because of limited knowledge by health workers, lack of specific symptoms and absence of more sensitive diagnostic procedures.

Human infection by fasciola hepatica in Venezuela: report of a geriatric case

Se reporta para la literatura parasitológica venezolana, un nuevo caso de infección humana por Fasciola hepatica. Se trata de una paciente de 81 años, asintomática, quien presentó durante exámenes de rutina, una eosinofilia de 21 por ciento y una eritsedimentación de 26 mm/h. Estos valores fueron normales para el momento del tratamiento (4 meses después), así como también lo eran varias pruebas de funcionamiento hepático, química sanguínea y valores hematológicos. El número de huevos del paciente fue de 90 a 130/g de heces. La paciente fue exitosamente tratada con la formulación humana de triclabendazol en 2 dosis simples de 10 mg/kg cada una separadas por 24h, resultado negativas las evaluaciones coproparasitológicas realizadas a los 12,18,60 y 120 días post-tratamiento. Los mismos tests de laboratorio arriba mencionados no mostraron modificaciones excepto por un incremento leve en el contaje de eosinófilos en los días 2 y 11, así como un incremento en los valores de eritrosedimentación al día 11 post-tratamiento. Así mismo, no.

Entomological evaluation by pool screen polymerase chain reaction of Onchocerca volvulus transmission in Ecuador following mass Mectizan distribution.

The prevalence of infected and infective black flies was estimated by pool screen polymerase chain reaction (PCR) amplification in the three river basins in Ecuador endemic for onchocerciasis. Mass distribution of ivermectin (Mectizan) resulted in dramatic declines in the prevalence of infected and infective flies. In the Rio Santiago river basin, no infections were detected, suggesting that transmission had ceased. The ratio of infected to infective flies in Simulium exiguum was 10-fold lower than the corresponding ratio for Simulium quadrivittatum, suggesting that S. exiguum is a more-competent vector for Onchocerca volvulus than S. quadrivittatum. However, the prevalence of infective flies in the two species was not different, suggesting that S. quadrivittatum may play an important vectorial role where it is the dominant human-biting species. The data demonstrate that pool screen PCR is an efficient way to monitor transmission in areas subject to control, and to certify an area as free of O. volvulus transmission.

Anterior uveitis after laser in situ keratomileusis.

PURPOSE: To report a case series of anterior uveitis after laser in situ keratomileusis (LASIK) and the incidence of anterior uveitis at a mean of 3 years. SETTING: Centro Medico Docente La Trinidad and Clinica Oftalmologica Centro Caracas, Caracas, Venezuela. METHODS: Five refractive surgeons and 18488 eyes that had surgical correction of a mean ametropia of -2.23 diopters (D) (range -10.25 to +4.25 D) participated in the study; 74.3% of the eyes were myopic. Laser in situ keratomileusis was performed in all eyes. Patients were followed for a mean of 36 months (range 6 to 48 months) after LASIK. The clinical charts of patients who developed uveitis after LASIK were reviewed. The mean preoperative intraocular pressure (IOP) was 15.2 mm Hg (range 12 to 19 mm Hg). The mean corneal ablation depth was 37.47 micro m (range 12 to 98 micro m). In the immediate postoperative period, all patients received a combination of topical dexamethasone and tobramycin. RESULTS: Thirty-five eyes (18 patients) developed anterior uveitis after LASIK. Signs and symptoms appeared a mean of 20.7 days (range 17 to 28 days) postoperatively and 5.08 days (range 2 to 8 days) after withdrawal of topical steroid and antibiotic agents. Eyes that developed LASIK-related uveitis had a mean preoperative spherical equivalent of -2.32 D (range -7.00 to +4.25 D). Intraocular pressure dropped to a mean of 8.0 mm Hg (range 4 to 12 mm Hg) at the onset of uveitis (P <.0001). The LASIK-related anterior uveitis resolved and IOP returned to baseline after a mean of 3 days on topical steroid and cycloplegic agents. Laboratory and immunology (including human leukocyte antigen-B27) tests were negative in 15 of 18 patients (83.33%). The incidence of uveitis after LASIK was 0.18%. CONCLUSIONS: Anterior uveitis after LASIK is infrequent. It may be due to uveal trauma during surgery with disruption of normal anterior-chamber-associated immune deviation, decreased antiinflammatory cytokines, and increased proinflammatory cytokines. Further studies are needed to investigate the mechanisms of this association.

Resultados de la vitrectomia combinada con implante de válvula de Ahmed e inserción del tubo vía pars plana / Results of the combined vitrectomy with it implant of ahmed and insert of the tube pathway pars plana

Evaluar los resultados de la vitrectomia combinada con implante de válvula de Ahmed e inserción del tubo vía pars plana en el manejo de glaucomas complicados. Se evaluaron respectivamente los resultados de vitrectomía combinada con implante de válvula de Ahmed e inserción del tubo vía pars plana dentro de una serie de 40 implantes valvulares realizados entre enero 1997 y julio 2000 en el Servicio de Oftalmología del Centro Clínico Docente la Trinidad. Se evaluó el "éxito quirúrgico", definido como: total, con una presión intraocular < 21 mmHg y >5 mmHg sin uso de medicación; parcial, igual al criterio anterior pero con uso de medicación; y fracaso, con una presión intraocular >21 mmHg aún con el uso de medicación. Otros parámetros evaluados fueron: mejor agudeza visual corregida (MAVC), presión intraocular, número de medicamentos y complicaciones asociadas al procedimiento. En 12 ojos de pacientes (Edad media 53,2 ñ 14,7 años y presión intraocular preoperatoria de 33,8 ñ 10,2 mmHg), se realizó vitrectomía combinada con implante de válvula de Ahmed e inserción del tubo vía pars plana. Durante el período promedio de seguimiento de 11,5 ñ 13,3 meses, se alcanzó el éxito total en 50,04 por ciento, parcial en 33,36 por ciento y fracaso en 16,6 por ciento de los casos, con una presión intraocular media postoperatoria de 15,3ñ2,9 mmHg, con una diferencia significativa en relación a la presión intraocular preoperatoria (p < 0,001) (ANOVA). La media de medicamentos en el preoperatorio fue 2,08 ñ 0,9 y en el posoperatorio 0,8 ñ 0,8, (p<0,01) (ANOVA). La MAVC mejoró en un 50 por ciento, se mantuvo en 41,6 por ciento y empeoró en el 8,3 por ciento de los casos. Se observaron complicaciones en un 25 por ciento de los casos. La vitrectomía combinada con implante de válvula de Ahmed e inserción del tubo vía pars plana constituye una opción válida en el manejo de glaucomas complicados

Paragonimiasis pulmonar en el Río Canande, Provincia de Esmeraldas / Pulmonary Paragonimiasis in the Canande River, Esmerald Province

Se estudiaron 137 muestras de esputo de adultos que habitan en un área endémica para paragonimiasis en laprovincia de Esmeraldas. En 10 individuos (7.11 por ciento) se observaron huevos de Paragonimus mexicanus en el esputo...

Evaluación de materiales útiles en la aplicación de Mitomicina C durante la cirugía filtrante / Evaluation of usefuls materials in the application of Mitomycin C during filtration surgery

Fueron determinadas las capacidades de absorción y liberación de 30 muestras de 4 tipos diferentes de materiales utilizados en la aplicación de Mitomicina C (MMC) durante la cirugía filtrante. Las microesponjas de celulosa (Grupo I) mostraron una capacidad de absorción y liberación mas uniforme y reproducible (coeficiente de variación de 6,4 y 7,7 respectivamente), lo que hace mas confiable el método de aplicación de MMC, utilizando éste material

Uso intraopertaorio de Mitomicina C en cirugía filtrante de glaucoma / Intraoperative use of mitomycin C in glaucoma filtering surgery

Evaluamos de forma retrospectiva los resultados y complicaciones de 17 trabeculectomías con el uso de Mitomicina C (MMC) con concentraciones de 0,2 y 0,4 mg/ml, aplicada durante 4 minutos en 16 pacientes con diferentes tipos de glaucoma entre enero de 1995 y junio de 1996. Definimos "exito completo" como el logro de presiones intraoculares postoperatorias (PIO) < o = 21 mm de Hg sin uso de medicación y "éxito parcial" como el logro de las mismas presiones pero con medicación coadyuvante. La edad media de los pacientes fue de 55,18 años, con una PIO media preoperatoria de 29,4 ñ 10,6 mm de Hg. Durante el seguimiento de 17,9 semanas se obtuvo un 94 por ciento de "éxito completo", con una PIO postoperatoria de 10.7 ñ 3,4 mm de Hg. Se observó un 24 por ciento de complicaciones relacionadas al uso de MMC. El uso de MMC durante la cirugía filtrante de glaucoma se asocia a una alta tasa de éxito. Las complicaciones relacionadas al uso de MMC si son adecuadamente manejadas no parecen afectar el éxito de la cirugía