Clinical, serological and DNA testing in Bengo Province, Angola further reveals low filarial endemicity and opportunities for disease elimination

The prevalence of Loa loa, Onchocerca volvulus and Wuchereria bancrofti infections in an under-surveyed area of Bengo Province, Angola, was determined by surveying 22 communities with a combination of clinical, serological and DNA diagnostics. Additional information was collected on participants' duration of residency, access to mass drug administration, knowledge of insect vectors and use of bednets. A total of 1616 individuals (38.1% male: 61.9% female), with an average age of 43 years, were examined. For L. loa, 6.2% (n = 100/16616) individuals were found to have eyeworm, based on the rapid assessment procedure for loiasis (RAPLOA) surveys, and 11.5% (n =178/1543) based on nested PCR analyses of venous blood. L. loa prevalences in long-term residents (>10 years) and older individuals (>60 years) were significantly higher, and older men with eyeworm were better informed about Chrysops vectors. For O. volvulus, 4.7% (n = 74/1567) individuals were found to be positive by enzyme-linked immunosorbent assay (Ov 16 ELISA), with only three individuals reporting to have ever taken ivermectin. For W. bancrofti, no infections were found using the antigen-based immunochromatographic test (ICT) and real-time PCR analysis; however, 27 individuals presented with lymphatic filariasis (LF) related clinical conditions (lymphoedema = 11, hydrocoele = 14, both = 2). Just under half (45.5%) of the participants owned a bednet, with the majority (71.1%) sleeping under it the night before. Our approach of using combination diagnostics reveals the age-prevalence of loiasis alongside low endemicity of onchocerciasis and LF. Future research foci should be on identifying opportunities for more cost-effective ways to eliminate onchocerciasis and to develop innovative surveillance modalities for clinical LF for individual disease management and disability prevention

FUNDING

A survey to evaluate the quality of malaria case management in outpatient health facilities, Huamb

Rapid integrated clinical survey to determine prevalence and co-distribution patterns of lymphatic filariasis and onchocerciasis in a co-endemic area:The Angolan experience

The Republic of Angola is a priority country for onchocerciasis and lymphatic filariasis (LF) elimination, however, the co-distribution of the filarial parasite Loa loa (loiasis) is a significant impediment, due to the risk of severe adverse events (SAEs) associated with ivermectin used in mass drug administration (MDA) campaigns. Angola has a high risk loiasis zone identified in Bengo Province where alternative interventions may need to be implemented; however, the presence and geographical overlap of the three filarial infections/diseases are not well defined. Therefore, this study conducted a rapid integrated filarial mapping survey based on readily identifiable clinical conditions of each disease in this risk zone to help determine prevalence and co-distribution patterns in a timely manner with limited resources. In total, 2007 individuals from 29 communities in five provincial municipalities were surveyed. Community prevalence estimates were determined by the rapid assessment procedure for loiasis (RAPLOA) and rapid epidemiological mapping of onchocerciasis (REMO) together with two questions on LF clinical manifestations (presence of lymphoedema, hydrocoele). Overall low levels of endemicity, with different overlapping distributions were found. Loiasis was found in 18 communities with a prevalence of 2.0% (31/1571), which contrasted to previous results defining the area as a high risk zone. Onchocerciasis prevalence was 5.3% (49/922) in eight communities, and LF prevalence was 0.4% for lymphoedema (8/2007) and 2.6% for hydrocoeles (20/761 males) in seven and 12 communities respectively. The clinical mapping survey method helped to highlight that all three filarial infections are present in this zone of Bengo Province. However, the significant difference in loiasis prevalence found between the past and this current survey suggests that further studies including serological and parasitological confirmation are required. This will help determine levels of infection and risk, understand the associations between clinical, serological and parasitological prevalence patterns, and better determine the most appropriate treatment strategies to reach onchocerciasis and LF elimination targets in the loiasis co-endemic areas. Our results also suggest that the utility of the earlier RAPLOA derived maps, based on surveys undertaken over a decade ago, are likely to be invalid given the extent of population movement and environmental change, particularly deforestation, and that fine scale micro-mapping is required to more precisely delineate the interventions required defined by these complex co-endemicities

The gravimetric method for the study of basic-ultrabasic plutonic complex in the SW Angola: geometry of the intrusions and their relation to metallic mineralization

Congreso realizado en Toledo del 28 de noviembre al 1 de diciembre de 2022.[EN] Angola is worldwide known as being one of the countries with the highest mineral resources, mainly diamonds, iron and gold. In the southwestern area, close to Lola, Quilengues and Lubango cities, distinct outcrops of Palaeoproterozoic (eburnean) igneous rocks, basic-intermediate in composition (gabbros, diorites and quartz-diorites), are found together with scarce ultrabasic (dunites, peridotites and hornblendites) bodies, which presumably contain Ni, Cr, Co and/or Platinum elements. We use gravity data in three selected structures (Quilengues, Cacimbas and Lola), with similar characteristics (diorites and quartz-diorites bodies with some hornblenditic units) with the aim to study the deep geometry and to evaluate the ore potential. Each structure has been studied with a series of gravimetric profiles, ca. 400 m apart and 100 m separation in between stations, achieving 997 gravity stations. We use the new Czech gravimeter Galileo LG1 (this survey serves to implement it during fieldwork). We use differential GPS by setting a base in each of the structures and connecting the GPS with radio connection, thus calculating the coordinates in real time. With this instrumentation and methodology, we achieve accuracies in accordance with the ranges established in this type of campaign. After obtaining the Bouguer anomaly map, residual anomaly maps have been deduced by adjusting a regional trend; they depict some relative maximum in areas where the ultramafic bodies (bearing base metals) draw sparse outcrops, suggesting higher volumes in depth. 2.5D gravimetric models show laccolithic intrusions, about 5 km of mainly dioritic bodies, with some scarce ultramafic rocks up to 3 km depth.Peer reviewe