Estimating the size of the monkeypox virus outbreak in Nigeria and implications for global control.

BACKGROUND: A multi-country outbreak caused by monkeypox virus (MPXV) has been unfolding across endemic and non-endemic countries since May 2022. Throughout April and May 2022, Nigeria reported 31 MPXV cases, of which 11 were confirmed via testing. In May 2022, three internationally exported cases of MPXV, presumed to have originated in Nigeria, were reported, suggesting that a larger than reported outbreak might be occurring in the country. METHODS: We used previously established methods to estimate the true size of the MPXV outbreak in Nigeria. We estimated the incidence rate of exported MPXV cases among all outbound international air travellers from Nigeria during the time period of April and May 2022, using forecasted air traveller volumes. We then applied this incidence rate to the entire population of Nigeria during April and May 2022 assuming that the rate of infection was the same in Nigeria for both travellers and the resident population. Information on the subset of population that were considered to be travellers was obtained from the United Nations World Tourism Organization (UNWTO). RESULTS: We estimated that there were approximately 4000 (N = 4013; 95% CI: 828-11 728) active cases of MPXV in Nigeria in April and May 2022. This is approximately 360-fold greater than the confirmed number and approximately 130-fold greater than the reported number of cases in Nigeria. CONCLUSION: Our findings suggest that a larger outbreak than is appreciated may be ongoing in Nigeria. The observed international spread of MPXV offers important insights into the scale of the epidemic at its origin, where clinical detection and disease surveillance may be limited. These findings highlight the need to expand and support clinical, laboratory, and public health capacity to enable earlier detection of epidemics of international significance.

A recyclable adsorbent for salinized groundwater: Dual-adsorbent desalination and potassium-exchanged zeolite production.

This study focused on advancing the dual-adsorbent desalination technique that sequentially combines calcined layered double hydroxide (CLDH) and acid-treated zeolites (H-form zeolite) using groundwater spiked with potash mining effluent (brine). In sequential batch experiments, the CLDH adsorbent first reduced the high Cl- concentration (4600 mg/L) of saline groundwater by 96%, the Ca2+ by 90%, and the Mg2+ by 92%, while transiently raising the pH to 12.80. H-form zeolites preconditioned with Na+ then removed 92% of the Na+ (2010 mg/L), while neutralizing the adsorption effluent pH to 7.7 and lowering the sodium adsorption ratio (SAR; 139.6 to 6.6) and the hardness (574 to 48.4 mg/L). In comparison, an equivalent amount of unmodified zeolite removed only 51% of the Na+ and generated extremely hard water due to Ca2+ and Mg2+ release (1519 mg/L). Na+-conditioning the zeolites prior to acid treatment enhances native cation removal, forming H-form zeolites. Synchrotron-based X-ray scanning transmission microscopy (STXM) showed the occurrence of dealumination and visualized the sodium distribution associated with Si and Al sites in the H-form zeolites. Four consecutive desalination cycles were feasible for Na+ and K+ adsorption by regenerating the H-form zeolite. During regeneration, the Na+ desorbed while the K+ remained in the regenerated zeolites. Cumulative K+ loading in the regenerated zeolites increased from 4.8 to 21.2 mg/g, producing K-form zeolites. These K-form zeolites released K+ (2.15 mg/L for 24 h) in a leaching test and could potentially be considered as nutrient-supply media in other applications, thereby recycling the spent zeolites after multiple desalination treatments.

Synergistic desalination of potash brine-impacted groundwater using a dual adsorbent.

The impact of saline mining effluent has been a significant environmental concern. Natural and modified clay-mineral adsorbents have been receiving increasing attention for salinity reduction of brine-impacted water, especially for natural resource extraction sites and surrounding environments. In this study, a dual-adsorbent treatment based on the sequential application of calcined layered double hydroxide (CLDH) and acid-treated zeolite was developed, evaluated and characterized for the desalination of potash brine-impacted groundwater. Potash brine produced by conventional potash mining in Saskatchewan (Canada) contains a large amount of Na+, K+ and Cl-. The CLDH and acid-treated clinoptilolite zeolites were combined to sequentially remove Cl- and Na+. A series of batch adsorption experiments were conducted for synthetic saline water and potash brine-spiked groundwater using various combinations of adsorbents: natural zeolites (NZ) or acid-treated zeolites (AZ) with or without the CLDH pretreatment. The experiment revealed that the Na+ removal percentage was synergistically increased by the dechlorination pretreatment using CLDH, and further improved by AZ. The CLDH-AZ dual adsorbent achieved a Langmuir Na+ adsorption capacity of 24.4mg/g, a significant improvement over conventional approaches to zeolite-based desalination. Using the brine-impacted groundwater with a high sodium adsorption ratio (SAR) of 13.3±0.1, the CLDH-AZ dual adsorbent decreased the concentrations of Na+, K+, and Cl- by 87, 97, and 87%, respectively (below drinking water standards). It also exhibited the additional advantages of neutralizing the effluent pH and decreasing the hardness, SAR, and total dissolved sulfur concentration. This study addresses the removal mechanisms, which are associated with the structural memory effect, dealumination, protonic exchanges, and zeolite porosity changes. Synchrotron-based scanning transmission X-ray microscopy analyses provided visual evidence of sodium adsorption sites (SiONa and AlONa) associated with dealumination in the acid-treated zeolites. This study is the first report that demonstrates the synergy of the CLDH-AZ dual adsorbent treatment for potash brine-impacted water.