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.

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