Spatial dependency of Buruli ulcer prevalence on arsenic-enriched domains in Amansie West District, Ghana: implications for arsenic mediation in Mycobacterium ulcerans infection

BACKGROUND: In 1998, the World Health Organization recognized Buruli ulcer (BU), a human skin disease caused by Mycobacterium ulcerans (MU), as the third most prevalent mycobacterial disease. In Ghana, there have been more than 2000 reported cases in the last ten years; outbreaks have occurred in at least 90 of its 110 administrative districts. In one of the worst affected districts, Amansie West, there are arsenic-enriched surface environments resulting from the oxidation of arsenic-bearing minerals, occurring naturally in mineral deposits. RESULTS: Proximity analysis, carried out to determine spatial relationships between BU-affected areas and arsenic-enriched farmlands and arsenic-enriched drainage channels in the Amansie West District, showed that mean BU prevalence in settlements along arsenic-enriched drainages and within arsenic-enriched farmlands is greater than elsewhere. Furthermore, mean BU prevalence is greater along arsenic-enriched drainages than within arsenic-enriched farmlands. CONCLUSION: The results suggest that arsenic in the environment may play a contributory role in MU infection

Geochemical analysis of evaporite sedimentation in the Gachsaran Formation, Zeloi oil field, Southwest Iran

In this study, the paleo-sedimentary depositional environment of the Gachsaran Formation and the Asmari reservoir cap rock (i.e., the stratigraphically lowest member of the Gachsaran Formation) was investigated from elemental geochemical data and mineralogical data obtained XRF and SEM analyses, respectively, of anhydrite samples collected from two oil wells in the Zeloi oil field in southwestern Iran. The present data reveal that arid conditions and cycles of transgression–regression of the sea contributed to the formation of evaporite sequences of the Gachsaran Formation in a coastal sabkha-lagoon basin that was partly closed to the sea. This interpretation was based on synthesis of statistical correlation analysis the geochemical data, chemostratigraphic correlation of geochemical ratios, and textural analysis of salts observed in SEM images