Some unfavourable effects of malnutrition of the host on Schistosoma mansoni worm biology and structure have been reported based upon brigthfield microscopy. This paper aims to study by morphometric techniques, some morphological parameters in male and female adult worms recovered from undernourished albino mice in comparison with parasites recovered from well-fed infected mice. Undernourished animals were fed a multideficient and essentially low protein diet (RBD diet) and compared to well-fed control mice fed with the commercial diet NUVILAB. Seventy-five days post-infection with 80 cercarie (BL strain) animals were sacrificed. All adult worms were fixed in 10% formalin and stained with carmine chloride. One hundred male and 60 female specimens from each group (undernourished and control) were examined using an image system analysis Leica Quantimet 500C and the Sigma Scan Measurement System. The following morphometrical parameters were studied: body length and width, oral and ventral suckers, number and area of testicular lobes, length and width of ovary and uterine egg. For statistical analysis, the Student's t test for unpaired samples was applied. Significant differences (p < 0.05) were detected in body length and width, in parameters of suckers, uterine egg width, ovary length and area of testicular lobes, with lower values for specimens from undernourished mice. The nutritional status of the host has negative influence on S. mansoni adult worms, probably through unavailability of essential nutrients to the parasites.

Malnutrition hampers the course of schistosomiasis mansoni infection just as normal growth of adult worms. A comparative morphometric study on adult specimens (male and female) recovered from undernourished (fed with a low protein diet - regional basic diet) and nourished (rodent commercial laboratory food, NUVILAB) white mice was performed. Tomographic images and morphometric analysis of the oral and ventral suckers, reproductive system and tegument were obtained by means of confocal laser scanning microscopy. Undernourished male specimens presented smaller morphometric values (length and width) of the reproductive system (first, third and last testicular lobes) and thickness of the tegument than controls. Besides that, it was demonstrated that the dorsal surface of the male worms bears large tubercles unevenly distributed, but kept grouped and flat. At the subtegumental region, vacuolated areas were detected. It was concluded that the inadequate nutritional status of the vertebrate host has a negative influence mainly in the reproductive system and topographical somatic development of male adult Schistosoma mansoni, inducing some alterations on the structure of the parasite.

The decision in 1987 by the pharmaceutical firm Merck & Co. to provide Mectizan® (ivermectin) free of charge to river blindness control programs has challenged the international public health community to find effective ways to distribute the drug to rural populations most affected by onchocerciasis. In the Americas, PAHO responded to that challenge by calling for the elimination of all morbidity from onchocerciasis from the Region by the year 2007 through mass distribution of ivermectin. Since 1991, a multinational, multiagency partnership (consisting of PAHO, the endemic countries, nongovernmental development organizations, the Centers for Disease Control and Prevention in Atlanta, Georgia, as well as academic institutions and funding agencies) has developed the political, financial, and technical support needed to move toward the realization of that goal. This partnership is embodied in the Onchocerciasis Elimination Program for the Americas (OEPA), which is supported by the River Blindness Foundation (RBF) and now by the Carter Center. OEPA was conceived as a means of maintaining a regional initiative to eliminate what is otherwise a low priority disease. Since its inception in 1993, the OEPA has provided more than US$ 2 million in financial, managerial, and technical assistance to stimulate and/or support programs in Brazil, Colombia, Ecuador, Guatemala, Mexico, and Venezuela, so as to take full advantage of the Merck donation. Now halfway into a five-year, US$ 4 million grant provided through the Inter-American Development Bank, the OEPA's capacity to support the regional initiative is assured through 1999.

La decisión tomada en 1987 por la Merck & Co., fabricante de productos farmacéuticos, de proveer Mectizan® (ivermectina) gratuitamente a los programas de control de la oncocercosis ha obligado a la comunidad sanitaria internacional a buscar formas de distribuir el medicamento a las poblaciones rurales que se ven más afectadas por la enfermedad. En las Américas, la OPS respondió al reto con un llamado a eliminar de la Región toda morbilidad por oncocercosis para el año 2007 mediante la distribución de ivermectina al público. Desde 1991, una alianza multinacional de diversas entidades (la OPS, países con oncocercosis endémica, agencias de desarrollo no gubernamentales, los Centros para el Control y la Prevención de Enfermedades en Atlanta, Georgia, instituciones académicas y agencias de financiamiento) ha generado el apoyo político, económico y técnico necesario para tratar de alcanzar esa meta. Esta alianza está representada por el Programa de Eliminación de la Oncocercosis en las Américas (OEPA), subvencionado por la Fundación Ceguera de los Ríos y actualmente por el Centro Carter. El OEPA se creó como iniciativa de alcance regional destinada a eliminar una enfermedad que no merece atención prioritaria. Desde su aparición en 1993, el OEPA ha aportado más de US$2 millones en ayuda económica, administrativa y técnica para fomentar y subvencionar programas en Brasil, Colombia, Ecuador, Guatemala, México y Venezuela, logrando así aprovechar al máximo la donación de la Merck & Co. Ahora que hemos llegado a la mitad de una subvención de 5 años y US$ 4 millones aportada por el Banco Interamericano de Desarrollo, se sabe que el OEPA tiene la capacidad para apoyar la iniciativa regional hasta fines de 1999.