Etude des répercussions de la pollution industrielle sur la riziculture dans la plaine de Laniera à Antananarivo, Madagascar

Face au développement urbain à Antananarivo, l'agriculture urbaine et péri-urbaine est exposée à la pollution industrielle. Les industries spécialisées dans le textile déversent leurs eaux usées dans le système d'irrigation, et polluent directement les champs de rizières à proximité des zones industrielles. Après 3 ans de suivi, l'effet de la pollution est variable et fonction de la situation et du processus industriel. Pendant la saison sèche, la pollution est très prononcée, alors que pendant la saison de pluie, les effets de dilution ont des impacts très importants sur la qualité de l'eau d'irrigation. Les effluents sont généralement colorés en bleu par le procédé de lavage de jeans, et sont riches en matières organiques en suspension. La qualité des effluents varie dans la journée : le pH de 3,9 à 10,6 et la conductivité électrique de 452 à 3620 μS / cm. Notre étude a pour but d’analyser la qualité de l'eau d'irrigation et d’observer les effets de la pollution sur les sols, les compositions chimiques des plants de riz et sur la production. En début de la saison culturale, l’effluent résulte une diminution du pH et une forte salinité dans les rizières. Le complexe absorbant du sol est chargé lentement en sodium. L'analyse de la paille montre un déséquilibre nutritionnel dans le plant de riz, notamment l'accumulation de potassium : K (14,5 à 22%), N (0,44 à 0,7%), du Ca (0,42 à 3%), Mg (0,02 à 0,95%), Na (0,35 à 0,8%), P (200 à 561 ppm). Quand la pollution est très élevée, on observe un allongement du cycle et une forte nutrition azotée. Le rendement en riz obtenu est faible (< 2t/ha), tandis que le rendement recueilli dans la plaine de Laniera peut atteindre jusqu’à 5t/ha.Mots-Clés: pollution, eau d’irrigation, industries textiles, pollution des sols, rizière, Laniera.Study of the repercussion of industrial pollution on rice production in plain of LANIERA in Antananarivo, Madagascar Faced to urban development in Antananarivo, urban and peri-urban agriculture is exposed on industrial pollution. Specialized textile industries discharge their wastewater into the circulating irrigation system, and pollute directly the rice fields near the industrial area. After 3 years of monitoring, the effect of pollution is variable and depending on the situation and the industrial process. During the dry season, the pollution is very high. But during the rainy season, dilution effects are very important to the quality of irrigation water. The effluents are usually colored in blue, from the activity for the jeans washing process and riches of suspended organic matters. The effluents quality varies on day, the pH from 3.9 to 10.6 and the electrical conductivity from 452 to 3620 μS/cm. Our study focused on the water irrigation quality and observed the effect on soil, the rice plant chemical compositions and on the production. At the first of the cropping cycle, effluents caused a lower pH and a high salinity in the rice fields. The absorbent complex is slowly charged in sodium concentration. Straw analysis provides the instability absorption of minerals nutriment in the rice, enriched by potassium accumulation: K (14.5 to 22 %), N (0.44 to 0.7 %), Ca (0,42 to 3 %), Mg (0.02 to 0.95 %), Na (0.35 to 0.8 %), and P (200 to 561 ppm). When pollution is very high, we observed an elongation cycle and a strong nitrogenous nutrition. The yield of paddy rice decreased (<2 t / ha), while the average yield collected in the plain of Laniera can be achieved to 5t/ha of paddy.Keywords: pollution, water irrigation, textiles industries, pollution of soil, rice field, Laniera

SEROPREVALENCE OF HIV, HEPATITIS B AND C AND SYPHILIS AMONG MEN HAVING SEX WITH MEN IN MAHAJANGA (MAGADASCAR)

Sexually transmitted diseases (STD) are public health concerns worldwide. The aim of our study is to assess infection and coinfection with HIV, hepatitis B, hepatitis C and syphilis among men having sex with men in Mahajanga which is a western coastal town of Madagascar. We conducted a prospective and descriptive preliminary study in the laboratory of the University Hospital Center PZAGA in Mahajanga during a period of three months, from December 2014 to February 2015. We included 100 MSM in our study. Their mean age was 36 yrs (16 to 55 yrs). We found 30% of seropositive men among our sample. HIV positive men are mainly part of the age group [20–29 yrs]. The mean age of positive men was respectively 38 yrs., 36 yrs., 48 yrs.  and 39 yrs. for HIV, for HBV, HCV, and syphilis. We found respectively for hepatitis B, hepatitis C and syphilis 7%, 1% and 11% positive samples. We found no co-infection HIV and HCV for them. But we found 5% of coinfection HIV-HBV, 4% of coinfection HIV-syphilis and 1% of coinfection of HIV, HBV and syphilis. We highlighted a very high rate of HIV positivity among MSM living in Mahajanga. Efforts have to be made in order to sensitize them about risky behaviors

SEROPREVALENCE OF HIV, HEPATITIS B AND C AND SYPHILIS AMONG MEN HAVING SEX WITH MEN IN MAHAJANGA (MAGADASCAR)

Sexually transmitted diseases (STD) are public health concerns worldwide. The aim of our study is to assess infection and coinfection with HIV, hepatitis B, hepatitis C and syphilis among men having sex with men in Mahajanga which is a western coastal town of Madagascar. We conducted a prospective and descriptive preliminary study in the laboratory of the University Hospital Center PZAGA in Mahajanga during a period of three months, from December 2014 to February 2015. We included 100 MSM in our study. Their mean age was 36 yrs (16 to 55 yrs). We found 30% of seropositive men among our sample. HIV positive men are mainly part of the age group [20–29 yrs]. The mean age of positive men was respectively 38 yrs., 36 yrs., 48 yrs.  and 39 yrs. for HIV, for HBV, HCV, and syphilis. We found respectively for hepatitis B, hepatitis C and syphilis 7%, 1% and 11% positive samples. We found no co-infection HIV and HCV for them. But we found 5% of coinfection HIV-HBV, 4% of coinfection HIV-syphilis and 1% of coinfection of HIV, HBV and syphilis. We highlighted a very high rate of HIV positivity among MSM living in Mahajanga. Efforts have to be made in order to sensitize them about risky behaviors