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BackgroundGiven the low levels of COVID-19 vaccine coverage in Sub-Saharan Africa, despite high levels of natural SARS-CoV-2 exposures, strategies for extending the breadth and longevity of naturally acquired immunity are warranted. Designing such strategies will require a good understanding of natural immunity.MethodsWe used ELISA to measure whole-spike IgG and spike-receptor binding domain (RBD) total immunoglobulins (Igs) on 585 plasma samples collected longitudinally over five successive time points within six months of COVID-19 diagnosis in 309 COVID-19 patients. We measured antibody neutralizing potency against the wild-type (Wuhan) SARS-CoV-2 pseudo-virus in a subset of 51 patients over three successive time points. Binding and neutralizing antibody levels and potencies were then tested for correlations with COVID-19 severities, graded according to the National Institute of Health (NIH), USA criteria.ResultsRates of sero-conversion increased from Day 0 (day of PCR testing) to Day 180 (six months) (63.6% to 100 %) and (69.3 % to 97%) for anti-spike IgG and anti-spike-RBD binding Igs, respectively. Levels of these binding antibodies peaked at Day 28 (P0.99). Similarly, antibody neutralizing potencies peaked at Day 28 (p0.6, PConclusionMost COVID-19 patients from Sub-Saharan Africa generate SARS-CoV-2 specific binding antibodies that remain stable during the first six months of infection. Although antibody binding levels and neutralizing potencies were directly correlated, the respective neutralizing antibodies decayed three-fold by the sixth month of COVID-19 diagnosis suggesting that they are short-lived, consistent with what has been observed elsewhere. Thus, just like for other populations, regular vaccination boosters will be required to broaden and sustain the high levels of predominantly naturally acquired anti-SARS-CoV-2 neutralizing antibodies.

Coronavirus Disease-2019 tests require a Nasopharyngeal (NP) and/or Oropharyngeal (OP) specimen from the upper airway, from which virus RNA is extracted and detected through quantitative reverse transcription-Polymerase Chain Reaction (qRT-PCR). The viability of the virus is maintained after collection by storing the NP/OP swabs in Viral Transport Media (VTM).We evaluated the performance of four transport media: locally manufactured (“REVITAL”) Viral Transport Media (RVTM), Standard Universal Transport Media (SUTM), PBS and 0.9% (w/v) NaCl (normal saline). We used laboratory cultured virus to evaluate: i) viral recovery and maintaining integrity at different time periods and temperatures; ii) stability in yielding detectable RNA consistently for all time points and conditions; and iii) their overall accuracy.Four vials of SARS-CoV-2 cultured virus (2 high and 2 low concentration samples) and 1 negative control sample were prepared for each media type (SUTM, RVTM, PBS and normal saline) and stored at the following temperatures, -80°C, 4°C, room temperature (25°C) and 37°C for 7 days. Viral Ribonucleic acid (RNA) extractions and qRT-PCR were done on the following days after inoculation with the cultured virus, days 1, 2, 3, 4 and 7 to assess virus stability and viral recovery.CT values fell over time at room temperature, but normal saline, PBS, RVTM and SUTM all showed comparable performance in maintaining virus integrity and stability allowing for the detection of SARS-CoV-2 viral RNA.Overall, this study demonstrated that normal saline, PBS and the locally manufactured VTM can be used for COVID-19 sample collection and testing, thus expanding the range of SARS-CoV-2 viral collection media.

The lack of access to potable water in Kitui has resulted to famine and high infant mortality rates, which has risen to 9.8% and life expectancy is declining steadily. The fact that the basement system is hard Precambrian rock, ground water tends to be more localized and thus sustainable wells cannot be dug on a trial and error basis. The aim of this project was to evaluate groundwater potential located in the concealed fractured /faulted zones which act as groundwater storage and conduits, using magnetic and geo-electrical geophysical techniques. A terrameter was used to collect resistivity data and subsequently determine the subsurface layer resistivity anomalies using Wenner profiling and resistivity sounding inversion software, IP2WIN. Proton precession magnetometer was used to measure the total magnetic field intensity of the earth and 2D Euler deconvolution software was used to model the disintegrated basement. Magnetic surveys showed distinct magnetic anomalies signifying disruption of the basement rock which occur due to faulting. Resistivity surveys also showed low resistivity anomaly at points of significant magnetic anomaly. This suggests groundwater potential in the inferred fault.

Rodents, like other wild animals, are subject to a wide variety of parasitic infestation. Although wild animals are usually infected with several species of parasites, they seldom suffer massive deaths or epizootic. This is due to the normal dispersal and territorialism of most species. Despite the fact that most wild animals tolerate their parasite burdens fairly well, the animals will succumb when crowded and suffering from malnutrition. This study investigated the occurrence and the variety of intestinal parasites among the different sub-populations of Praomys delectorum in Taita and Kyulu Hills. Microscopic studies were conducted on the digesta of the animals. Threedifferent species of intestinal parasites were identified i.e. Hymenolepis sp, Trichostronglus sp and Trichuris sp. All the animal groups were found to have the ova and the adult Hymenolepis sp and only the Kyulu group had Trichuris species ova. The percentage infection varied between 25% and 63.16% across all the sub-populations. The Kyulu sub-population with the leastanthropogenic disturbance or a more stable ecosystem had the highest prevalence of parasites (63.16%). Of the Taita Hills sub-populations, Ngangao, with the least anthropogenic disturbance and lowest population of Praomysdelectorum, had the lowest prevalence of intestinal parasites at 25%. Density of rodent population, habitat type and degree of anthropogenic disturbance are factors that determine the occurrence and prevalence of intestinal parasites in the animal species under study.

Includes abstract., Includes bibliographical references (leaves [124]-128)., The main objective of this study is the selection and design of a wind generator to meet electrolyser requirements. These are the hydrogen production rate, the power requirements and the operating temperature. This requires the analysis of the load, sizing and characterizing of an electrolyser and finally, the design of a wind generator that meets electrolyser requirements. A hybrid system that combines the use of hydrogen as an efficient form of energy storage, and the growing renewable energy (RE) industry is discussed in detail.