Some epidemiological consequences of drastic ecosystem changes accompanying exploitation of tropical rain forest

Les auteurs donnent quelques exemples des conséquences épidémiologiques inattendues de la modification drastique de l’écosystème forestier tropical humide par les activités humaines. L’homme est exposé aux effets débilitants, voire mortels, d’agents infectieux auxquels certains animaux sauvages servent de réservoirs et chez lesquels ils n’entraînent que des affections bé nignes, voire inapparentes. Les relations complexes existant entre parasites et arbovirus d’une part, réservoirs et vecteurs d’autre part, sont illustrées par les cas bien connus de la fièvre jaune et de la maladie de Kyasanur. Les végétaux cultivés peuvent aussi être infectés par des virus ou des ravageurs divers, normalement inoffensifs pour les popu lations de plantes sauvages. Des exemples en sont donnés dans le cas des plantations de Cacaoyers attaquées par des virus, des champignons et des insectes. Les nouveaux complexes pathogènes ainsi créés peuvent avoir des conséquences désastreuses tant pour l’homme que pour ses cultures vivrières ou industrielles.The epidemiological consequences of tropical rainforest exploitation are discussed in terms of the effects on both exotic and native elements of the community. Incursion exposes man to debilitating or fatal infections/infestations having reservoirs in the wild fauna. As examples, the ecological relations of blood parasites ( Brugia malayi and Plasmodium spp) and arboviruses having mosquito (yellow fever) or tick (Kyasanur forest disease) vectors are discussed. Agricultural crops may be similarly affected by pests/patho gens naturally present in the flora ; by viruses (e.g. cocoa swollen shoot/mottle leaf), insects (e.g. Tiracola plagiata) and fungi (e.g. Microcyclus ulei, Ganoderma, Fomes and Armitlaria spp). The harmful consequences for indigenous humans are illustrated with reference to the effects of measles and influenza on immuno- logically and/or chemo therapeutically unprotected persons. Some of the risks to the world’s population as a whole, have been considered in the light of fragmentary information concer ning animal viruses (e.g. monkey pox, lassa fever, herpes virus B) and plant pathogens/pests which have spread from local foci of typically inapparent infection to cause devastation elsewhere

The global atmospheric electrical circuit and climate

Evidence is emerging for physical links among clouds, global temperatures, the global atmospheric electrical circuit and cosmic ray ionisation. The global circuit extends throughout the atmosphere from the planetary surface to the lower layers of the ionosphere. Cosmic rays are the principal source of atmospheric ions away from the continental boundary layer: the ions formed permit a vertical conduction current to flow in the fair weather part of the global circuit. Through the (inverse) solar modulation of cosmic rays, the resulting columnar ionisation changes may allow the global circuit to convey a solar influence to meteorological phenomena of the lower atmosphere. Electrical effects on non-thunderstorm clouds have been proposed to occur via the ion-assisted formation of ultra-fine aerosol, which can grow to sizes able to act as cloud condensation nuclei, or through the increased ice nucleation capability of charged aerosols. Even small atmospheric electrical modulations on the aerosol size distribution can affect cloud properties and modify the radiative balance of the atmosphere, through changes communicated globally by the atmospheric electrical circuit. Despite a long history of work in related areas of geophysics, the direct and inverse relationships between the global circuit and global climate remain largely quantitatively unexplored. From reviewing atmospheric electrical measurements made over two centuries and possible paleoclimate proxies, global atmospheric electrical circuit variability should be expected on many timescale

Broad Bean Mottle Virus: Identification, Serology, Host Range, and Occurrence on Faba Bean (Vicia Faba) in West Asia and Norm Africa

One of the faba bean viruses found in West Asia and North Africa was identified as broad bean mottle virus (BBMV) by host reactions, particle morphology and size, serology, and granular, often vesiculated cytoplasmic inclusions. Detailed research on four isolates, one each from Morocco, Tunisia, Sudan and Syria, provided new information on the virus. The isolates, though indistinguishable in ELISA or gel-diffusion tests, differed slightly in host range and symptoms. Twenty-one species (12 legumes and 9 non-legumes) out of 27 tested were systemically infected, and 14 of these by all four isolates. Infection in several species was symptomless, but major legumes such as chickpea, lentil and especially pea, suffered severely from infection. All 23 genotypes of faba bean, 2 of chickpea, 4 of lentil, 11 out of 21 of Phaseolus bean, and 16 out of 17 of pea were systemically sensitive to the virus. Twelve plant species were found to be new potential hosts and cucumber a new local-lesion test plant of the virus. BBMV particles occurred in faba bean plants in very high concentrations and seed transmission in this species (1.37%) was confirmed. An isolate from Syria was purified and two antisera were produced, one of which was used in ELISA to detect BBMV in faba bean field samples. Two hundred and three out of the 789 samples with symptoms suggestive of virus infection collected in 1985, 1986 and 1987, were found infected with BBMV: 4 out of 70 (4/70) tested samples from Egypt, 0/44 from Lebanon, 1/15 from Morocco, 46/254 from Sudan, 72/269 from Syria and 80/137 from Tunisia. This is the first report on its occurrence in Egypt, Syria and Tunisia. The virus is a potential threat to crop improvement in the region