Maturity, age and growth of Oreochromis karongae (Teleostei: cichlidae) in Lake Malawi and Lake Malombe

Size-at-50% maturity, age and growth, of Oreochromis (Nyasalapia) karongae (‘chambo’) in Lakes Malawi and Malombe were studied. Similar size-at-50% maturity and growth patterns were found for populations in Lake Malawi, but differences were observed for Lake Malombe populations, suggesting that current chambo fisheries management regulations, based on findings from the southern part of Lake Malawi, may be applicable to the central and southern parts of that lake, but not to Lake Malombe

Modelling and simulation of reactive transport phenomena

Mathematical modelling and numerical simulation of chemical transport phenomena are very challenging due to large numbers of species and reactions involved. Reactive transport models for such systems have high degrees of freedom, and therefore, are computationally expensive to solve. In this discussion, we present and numerically analyse stoichiometric decoupling method for reducing the high degrees of freedom and hence, cost of simulation. This method is a model reduction procedure that is based on some key properties of chemical systems. A multi-scale model of a passive treatment method for acidic mine effluents is used to test the efficacy of the reduction procedure. Moreover, reduced models are characteristically non-linear and stiff, thus, we used numerical techniques to study the reduction error in order to establish compatibility/efficiency of the reduction procedure.AEA acknowledges support from the Pilot Bursary of the University of Pretoria, the African Institute of Mathematical Sciences and University of Stellenbosch. This work is also supported in part by the National Research Foundation of South Africa (Grant Number: 93099 and 93476).http://www.elsevier.com/locate/jocs2019-09-01hj2018Mathematics and Applied Mathematic

A stoichiometric method for reducing simulation cost of chemical kinetic models

Mathematical models for chemically reacting systems have high degrees of freedom (very large) and are computationally expensive to analyse. In this discussion, we present and analyse a model reduction method that is based on stoichiometry and mass balances. This method can significantly reduce the high degrees of freedom of such systems. Numerical simulations are undertaken to validate and establish efficiency of the method. A practical example of acid mine drainage is used as a test case to demonstrate the efficacy of the procedure. Analytical results show that the stoichiometrically-reduced model is consistent with the original large model, and numerical simulations demonstrate that the method can accelerate convergence of the numerical schemes in some cases.AEA acknowledges support from the Pilot Bursary of the University of Pretoria, the African Institute of Mathematical Sciences and University of Stellenbosch. MKB is grateful to the African Institute for Mathematical Sciences (AIMS) for hosting him while finalising this work. This work is also supported in part by the National Research Foundation of South Africa (Grant number: 93099 and 93476).http://www.elsevier.com/locate/com/pchemeng2019-04-06hj2018Mathematics and Applied Mathematic

Assessing the Validity of Sexual Behaviour Reports in a Whole Population Survey in Rural Malawi

Background: Sexual behaviour surveys are widely used, but under-reporting of particular risk behaviours is common, especially by women. Surveys in whole populations provide an unusual opportunity to understand the extent and nature of such under-reporting.Methods: All consenting individuals aged between 15 and 59 within a demographic surveillance site in northern Malawi were interviewed about their sexual behaviour. Validity of responses was assessed by analysis of probing questions; by comparison of results with in-depth interviews and with Herpes simplex type-2 (HSV-2) seropositivity; by comparing reports to same sex and opposite sex interviewers; and by quantifying the partnerships within the local community reported by men and by women, adjusted for response rates.Results: 6,796 women and 5,253 men (83% and 72% of those eligible) consented and took part in sexual behaviour interviews. Probing questions and HSV-2 antibody tests in those who denied sexual activity identified under-reporting for both men and women. Reports varied little by sex or age of the interviewer. The number of marital partnerships reported was comparable for men and women, but men reported about 4 times as many non-marital partnerships. The discrepancy in reporting of non-marital partnerships was most marked for married women (men reported about 7 times as many non-marital partnerships with married women as were reported by married women themselves), but was only apparent in younger married women.Conclusions: We have shown that the under-reporting of non-marital partnerships by women was strongly age-dependent. The extent of under-reporting of sexual activity by young men was surprisingly high. The results emphasise the importance of triangulation, including biomarkers, and the advantages of considering a whole population

Are venue-based strategies the ticket to the last mile in HIV prevention in Malawi

Background: In 2016, Blantyre District had the highest adult HIV prevalence in Malawi (17% overall; 22% in women) and the lowest viral suppression rate (60%). In response, the MOH expanded prevention and treatment strategies. We hypothesized that social venues patronized by people with high sexual partnerships rates could identify sub-groups currently missed. Methods: We conducted cross-sectional bio-behavioral surveys of representative samples of individuals seeking care in government clinics (n=2313) and social venue patrons (n=1802) Jan-Mar 2022. Clinics were randomly selected from government clinics providing HIV testing. Venues were randomly sampled from urban and rural strata with oversampling of rural venues. Sampling weights were based on 2-stage sampling probabilities. We followed national testing protocols for rapid tests, recency testing and viral load measurements. Acute infections were identified by pooling dried blood spots from persons with an HIV- rapid test. Results: Compared to the clinic population, the venue population was more likely to: be male (68% vs 28%); aged >25 years (61% vs 51%); unmarried (62% vs 40%); drink alcohol daily (43% vs 8%); have more sexual partners in the last year (mean 16 vs 2); report a new sex partner in the past 4 weeks (42% vs 14%); and report transactional sex (52% vs 12%). HIV prevalence (Table 1) was higher among the venue population (19% vs 9%); the proportion HIV+ suppressed was similar (78%). Among women recruited at venues, prevalence increased by age: 0% among age 15-17 to 41% among age 18-21. At venues, factors associated with HIV infection include female sex (39% vs 10%); having a new partner in the past 4 weeks (28% vs 13%) and transactional sex (25% vs 13%). Acute and recent infections were uncommon. Clinic participants who reported visiting venues were less likely to have a suppressed viral load than other PLHIV clinic participants (53% vs 81%). Among both populations, reporting a genital sore in the past 4 weeks was associated with non-suppression (40% vs 20% in clinic; 48% vs 20% in venues). Conclusions: Lower HIV prevalence and greater viral suppression suggests that Blantyre’s HIV epidemic is slowing. Strategies to further reduce transmission should include outreach to venues with higher prevalence of unsuppressed infection and to young women at venues. Testing for acute or recent infection yielded few cases and thus did not provide sufficient value to warrant the cost

DISTRIBUCIÓN Y CONDICIONES ECOGEOGRÁFICAS DEL BOSQUE RELICTO DE Abies EN ZONAS MONTAÑOSAS DE TAMAULIPAS.

En el noreste de México, el género Abies forma bosques considerados relictos, con distribución sólo reconocida por instancias gubernamentales para el estado de Nuevo León. Dentro del estado de Tamaulipas se conocen cuatro especies de Abies que se encuentran enlistadas por IUCN, pero sólo dos de ellas (A. vejarii y A. guatemalensis) forman bosques, siendo las que se encuentran en categorías mexicanas de protección. El uso herramientas gratuitas de visualización y modelación geoespacial permitió estudiar la distribución relicta de estos bosques tamaulipecos. A través de Puntos de Control en Campo (PCC) se registraron factores ecogeográficos de tres sitios de este bosque, mismos que permitieron establecer características ópticas sobre imágenes de satélite del visualizador Google Earth™. Con los valores de altitud, pendiente y exposición, se obtuvo un primer modelo (de aproximación), usando álgebra booleana con el módulo Spatial Analyst para ArcView 3.2 de ESRI™, que se sobrepuso a las imágenes del visualizador, para ajustarlo y obtener un modelo principal. Este modelo sirvió, a su vez, como auxiliar para encontrar la distribución potencial, ya que primero se buscaron registros de Abies en bases de datos, los cuales se sobrepusieron al modelo principal en Google Earth™, para saber si se encontraban en sitios con características ópticas de bosque similares a los puntos de control; otros puntos fueron agregados sobre el visualizador en lugares donde el INEGI registra la presencia del bosque en Nuevo León. Posteriormente, se obtuvieron los valores para cada una de las variables de BioClim de los diez puntos obtenidos, estableciendo rangos que fueron procesados a través de álgebra booleana; además, se aplicó un análisis de clústers para obtener la similitud bioclimática entre los sitios. La distribución potencial también fue sobrepuesta en Google Earth™ para repetir el proceso de ajuste del modelo y obtener así la distribución real del bosque de oyamel en Tamaulipas. De esta forma, se obtuvo como resultado una superficie potencial de 165.9 Km2, pero la distribución real es de apenas 3.68 Km2, lo que representa menos del 1% del territorio estatal. En los PCCs se presentan condiciones de humedad y temperatura templada todo el año, que son producto de la exposición e inclinación de la ladera, donde la humedad depende de la altitud en los sitios de la Sierra Madre Oriental, y de la cercanía al Golfo de México el bosque de la Sierra de San Carlos, que es la forma de disgregación principal obtenida a través del análisis de similitud. Además de estas condiciones, otros factores han permitido la prevalencia de los bosques en Tamaulipas, principalmente a su aislamiento y acceso difícil, lo que no son aprovechados comercialmente. Algunos lugares de la distribución potencial se encuentran ocupados principalmente por bosques de pino, pero gran parte de la superficie ha sido afectada principalmente por incendios, por lo que presentan chaparrales, matorrales o pastizales inducidos. Por ser un ecosistema aislado y relictual, formado de especies en riesgo y que además no cuenta con protección oficial, puede presentar niveles significativos de fragilidad y vulnerabilidad, especialmente ante las condiciones cambiantes del clima planetario. Conocer su distribución sienta bases para estudios más profundos y estrategias de conservación adecuadas a estos bosques. Finalmente, y a pesar de la limitación de cartografía digital a gran detalle, las herramientas geoespaciales y el método empleado resultaron adecuados para modelar la distribución real del bosque de Abies en el Tamaulipas, siendo más apropiado que el uso de algoritmos de nicho ecológico, debido principalmente a que estos dependen de un elevado número de registros

Micronutrient fortification to improve growth and health of maternally HIV-unexposed and exposed Zambian infants: a randomised controlled trial

Background: The period of complementary feeding, starting around 6 months of age, is a time of high risk for growth faltering and morbidity. Low micronutrient density of locally available foods is a common problem in low income countries. Children of HIV-infected women are especially vulnerable. Although antiretroviral prophylaxis can reduce breast milk HIV transmission in early infancy, there are no clear feeding guidelines for after 6 months. There is a need for acceptable, feasible, affordable, sustainable and safe (AFASS by WHO terminology) foods for both HIV-exposed and unexposed children after 6 months of age. Methods and Findings: We conducted in Lusaka, Zambia, a randomised double-blind trial of two locally made infant foods: porridges made of flour composed of maize, beans, bambaranuts and groundnuts. One flour contained a basal and the other a rich level of micronutrient fortification. Infants (n = 743) aged 6 months were randomised to receive either regime for 12 months. The primary outcome was stunting (length-for-age Z < -2) at age 18 months. No significant differences were seen between trial arms overall in proportion stunted at 18 months (adjusted odds ratio 0.87; 95% CI 0.50, 1.53; P = 0.63), mean length-for-age Z score, or rate of hospital referral or death. Among children of HIV-infected mothers who breastfed <6 months (53% of HIV-infected mothers), the richly-fortified porridge increased length-for-age and reduced stunting (adjusted odds ratio 0.17; 95% CI 0.04, 0.84; P = 0.03). Rich fortification improved iron status at 18 months as measured by hemoglobin, ferritin and serum transferrin receptors. Conclusions: In the whole study population, the rich micronutrient fortification did not reduce stunting or hospital referral but did improve iron status and reduce anemia. Importantly, in the infants of HIV-infected mothers who stopped breastfeeding before 6 months, the rich fortification improved linear growth. Provision of such fortified foods may benefit health of these high risk infants

Population-Level Reduction in Adult Mortality after Extension of Free Anti-Retroviral Therapy Provision into Rural Areas in Northern Malawi

BACKGROUND: Four studies from sub-Saharan Africa have found a substantial population-level effect of ART provision on adult mortality. It is important to see if the impact changes with time since the start of treatment scale-up, and as treatment moves to smaller clinics. METHODS AND FINDINGS: During 2002-4 a demographic surveillance site (DSS) was established in Karonga district, northern Malawi. Information on births and deaths is collected monthly, with verbal autopsies conducted for all deaths; migrations are updated annually. We analysed mortality trends by comparing three time periods: pre-ART roll-out in the district (August 2002-June 2005), ART period 1 (July 2005-September 2006) when ART was available only in a town 70 km away, and ART period 2 (October 2006-September 2008), when ART was available at a clinic within the DSS area. HIV prevalence and ART uptake were estimated from a sero-survey conducted in 2007/2008. The all-cause mortality rate among 15-59 year olds was 10.2 per 1000 person-years in the pre-ART period (288 deaths/28285 person-years). It fell by 16% in ART period 1 and by 32% in ART period 2 (95% CI 18%-43%), compared with the pre-ART period. The AIDS mortality rate fell from 6.4 to 4.6 to 2.7 per 1000 person-years in the pre-ART period, period 1 and period 2 respectively (rate ratio for period 2 = 0.43, 95% CI 0.33-0.56). There was little change in non-AIDS mortality. Treatment coverage among individuals eligible to start ART was around 70% in 2008. CONCLUSIONS: ART can have a dramatic effect on mortality in a resource-constrained setting in Africa, at least in the early years of treatment provision. Our findings support the decentralised delivery of ART from peripheral health centres with unsophisticated facilities. Continued funding to maintain and further scale-up treatment provision will bring large benefits in terms of saving lives

A scorecard of progress towards measles elimination in 15 west African countries, 2001-19: a retrospective, multicountry analysis of national immunisation coverage and surveillance data.

BACKGROUND: The WHO Regional Office for the Africa Regional Immunization Technical Advisory Group, in 2011, adopted the measles control and elimination goals for all countries of the African region to achieve in 2015 and 2020 respectively. Our aim was to track the current status of progress towards measles control and elimination milestones across 15 west African countries between 2001 and 2019. METHODS: We did a retrospective multicountry series analysis of national immunisation coverage and case surveillance data from Jan 1, 2001, to Dec 31, 2019. Our analysis focused on the 15 west African countries that constitute the Economic Community of West African States. We tracked progress in the coverage of measles-containing vaccines (MCVs), measles supplementary immunisation activities, and measles incidence rates. We developed a country-level measles summary scorecard using eight indicators to track progress towards measles elimination as of the end of 2019. The summary indicators were tracked against measles control and elimination milestones. FINDINGS: The weighted average regional first-dose MCV coverage in 2019 was 66% compared with 45% in 2001. 73% (11 of 15) of the west African countries had introduced second-dose MCV as of December, 2019. An estimated 4 588 040 children (aged 12-23 months) did not receive first-dose MCV in 2019, the majority (71%) of whom lived in Nigeria. Based on the scorecard, 12 (80%) countries are off-track to achieving measles elimination milestones; however, Cape Verde, The Gambia, and Ghana have made substantial progress. INTERPRETATION: Measles will continue to be endemic in west Africa after 2020. The regional measles incidence rate in 2019 was 33 times the 2020 elimination target of less than 1 case per million population. However, some hope exists as countries can look at the efforts made by Cape Verde, The Gambia, and Ghana and learn from them. FUNDING: None