Patients who return to care after tracking remain at high risk of attrition: experience from a large HIV clinic, Uganda.

We determined the retention rate of patients infected with HIV who resumed care after being tracked at the Infectious Diseases Clinic (IDC) in Kampala, Uganda. Between April 2011 and September 2013, patients who missed their clinic appointment for 8-90 days were tracked, and those who returned to the clinic within 120 days were followed up. The proportion of patients retained among tracked patients, and those who resumed care before tracking started was compared. At 18 months of follow up, 33 (39%) of the tracked patients and 72 (61%) of those who had resumed care before tracking started were retained in care. The most important cause of attrition among the traceable was self-transfer to another clinic (38 [73%] patients), whereas among those who resumed care before tracking was loss to follow up (LTFU) (32 [71%] patients). Tracked patients who resume care following a missed appointment are at high risk of attrition. To increase retention, antiretroviral therapy clinics need to adopt a chronic care model which takes into consideration patients' changing needs and their preference for self-management.

Understanding the fate of sanitation-related nutrients in a shallow sandy aquifer below an urban slum area.

We hypothesized that wastewater leaching from on-site sanitation systems to alluvial aquifers underlying informal settlements (or slums) may end up contributing to high nutrient loads to surface water upon groundwater exfiltration. Hence, we conducted a hydro-geochemical study in a shallow sandy aquifer in Bwaise III parish, an urban slum area in Kampala, Uganda, to assess the geochemical processes controlling the transport and fate of dissolved nutrients (NO3, NH4 and PO4) released from on-site sanitation systems to groundwater. Groundwater was collected from 26 observation wells. The samples were analyzed for major ions (Ca, Mg, Na, Mg, Fe, Mn, Cl and SO4) and nutrients (o-PO4, NO3 and NH4). Data was also collected on soil characteristics, aquifer conductivity and hydraulic heads. Geochemical modeling using PHREEQC was used to determine the level of o-PO4 control by mineral solubility and sorption. Groundwater below the slum area was anoxic and had near neutral pH values, high values of EC (average of 1619µS/cm) and high concentrations of Cl (3.2mmol/L), HCO3 (11mmol/L) and nutrients indicating the influence from wastewater leachates especially from pit latrines. Nutrients were predominantly present as NH4 (1-3mmol/L; average of 2.23mmol/L). The concentrations of NO3 and o-PO4 were, however, low: average of 0.2mmol/L and 6µmol/L respectively. We observed a contaminant plume along the direction of groundwater flow (NE-SW) characterized by decreasing values of EC and Cl, and distinct redox zones. The redox zones transited from NO3-reducing in upper flow areas to Fe-reducing in the lower flow areas. Consequently, the concentrations of NO3 decreased downgradient of the flow path due to denitrification. Ammonium leached directly into the alluvial aquifer was also partially removed because the measured concentrations were less than the potential input from pit latrines (3.2mmol/L). We attributed this removal (about 30%) to anaerobic ammonium oxidation (anammox) given that the cation exchange capacity of the aquifer was low (<6meq/100g) to effectively adsorb NH4. Phosphate transport was, on the other hand, greatly retarded and our results showed that this was due to the adsorption of P to calcite and the co-precipitation of P with calcite and rhodochrosite. Our findings suggest that shallow alluvial sandy aquifers underlying urban slum areas are an important sink of excessive nutrients leaching from on-site sanitation systems.

Factors before enrolment are associated with being removed from a Pharmacy-only Refill Programme at a large urban HIV/AIDS clinic, Uganda.

A Pharmacy-only Refill Programme (PRP) a type of task shifting in which stable HIV-positive patients are managed through pharmacy-only visits instead of physician visits. We performed a study to identify factors for being removed from the PRP in order to establish better referral criteria. The study was performed at the Infectious Disease Clinic (IDC) in Kampala, Uganda. We selected a random sample of 588 patients from 2431 patients on antiretroviral therapy referred to the PRP at least 12 months before commencement of the PRP evaluation. We compared the characteristics of patients who during 12 months of follow-up were removed from the PRP with those who continued to be followed up. Data were abstracted from the IDC data base, the pharmacy register and the patient clinical notes. Of 588 patients, 106 (18%) were removed from the PRP. In multivariate analysis, less than 100% self-reported adherence to antiretroviral therapy, missing at least one scheduled appointment in the six months before referral to the PRP and being on a lopinavir/ritonavir-containing regimen were independently associated with being removed from the PRP. Criteria for referring patients to a PRP should focus on antiretroviral therapy adherence and appointment keeping. Patients on a lopinavir/ritonavir-containing regimen should not be targeted for a PRP. On the other hand a PRP is an efficient strategy that targets stable adherent patients in clinics with high patient load.

Nutrient pollution in shallow aquifers underlying pit latrines and domestic solid waste dumps in urban slums.

The lack of proper on-site sanitation in unsewered low-income areas is becoming an important source of nutrient-rich wastewater leaching to groundwater and can potentially lead to eutrophication. For typical conditions in sub-Saharan Africa, the nutrient loading of nitrogen (N) and phosphorus (P) from on-site sanitation systems to aquifers is largely unknown. In this study, we assessed the dissolved nutrient loads (nitrate (NO3), ammonium (NH4) and orthophosphate (o-PO4)) and the processes likely affecting them in aquifers underlying two on-site sanitation systems in an unsewered low-income urban slum in Kampala, Uganda; a domestic solid waste dump and a site with two pit latrines. The impact of the two types of sites was assessed by comparing the upgradient and downgradient nutrient concentrations and loads along groundwater flow lines. Significant pollution to groundwater originated from the pit latrine site with downgradient nutrient loads increasing by factors of 1.7 for NO3, 10.5 for NH4 and 49 for o-PO4. No effect of leaching of nutrients to groundwater was found from the waste dump. We estimated that approximately 2-20% of total N and less than 1% of total P mass input was lost to groundwater from the pit latrines. The bulk of N leached to groundwater was in the form of NH4. Mn-reducing conditions prevailed in the shallow aquifer which suggested that nitrification was the main process affecting NH4 concentrations. Phosphorus was likely retained in the soils by precipitating as MnHPO4 and Ca5(PO4)3(OH). Our results indicated that pit latrines in alluvial aquifer systems can be highly effective for the removal of nutrients depending on hydrological, hydrochemical and geochemical conditions in the aquifer receiving wastewater. Improvements to make the current pit latrine systems better for nutrient containment are suggested based on findings from this study.

Eutrophication and nutrient release in urban areas of sub-Saharan Africa--a review.

Eutrophication is an increasing problem in sub-Saharan Africa (SSA), and, as a result, the ecological integrity of surface waters becomes compromised, fish populations become extinct, toxic cyanobacteria blooms are abundant, and oxygen levels reduce. In this review we establish the relationship between eutrophication of fresh inland surface waters in SSA and the release of nutrients in their mega-cities. Monitoring reports indicate that the population of mega-cities in SSA is rapidly increasing, and so is the total amount of wastewater produced. Of the total amounts produced, at present, less than 30% is treated in sewage treatment plants, while the remainder is disposed of via onsite sanitation systems, eventually discharging their wastewater into groundwater. When related to the urban water balance of a number of SSA cities, the total amount of wastewater produced may be as high as 10-50% of the total precipitation entering these urban areas, which is considerable, especially since in most cases, precipitation is the most important, if not only the 'wastewater diluting agent' present. The most important knowledge gaps include: (1) the fate and transport mechanisms of nutrients (N and P) in soils and aquifers, or, conversely, the soil aquifer treatment characteristics of the regoliths, which cover a large part of SSA, (2) the effect of the episodic and largely uncontrolled removal of nutrients stored at urban surfaces by runoff from precipitation on nutrient budgets in adjacent lakes and rivers draining the urban areas, and (3) the hydrology and hydrogeology within the urban area, including surface water and groundwater flow patterns, transport velocities, dynamics of nutrient transport, and the presence of recharge and discharge areas. In order to make a start with managing this urban population-related eutrophication, many actions are required. As a first step, we suggest to start systematically researching the key areas identified above.

Improvement of the patient flow in a large urban clinic with high HIV seroprevalence in Kampala, Uganda.

Antiretroviral treatment roll-out programmes in Africa often have difficulties to cope with the increasing number of clients. Based on the findings of a survey carried out in 2005 that showed long waiting times, innovative organizational changes (nurse visits and pharmacy-only refill visits) were introduced in our clinic. In August 2007, the survey was repeated to evaluate the impact of these changes. During both surveys we used the same standardized questionnaire. In 2007, 400 patients visited the clinic on the study day compared to 250 in 2005. The median time spent at the clinic decreased from 157 minutes in 2005 (range 22-426) to 124 minutes (15-314). All the waiting times for different services decreased except the time between the visit to the triage nurse and the doctors' visit. A similar methodology could be used by other health services to evaluate and compare different models of care.