Search

• We assessed and included 123 eligible studies across 13 countries in Africa. • An inventory of 55 Aloe species was generated as remedies against 9 disease categories. • Aloe vera was the most popular Aloe species with ethnoveterinary applications. • Aloe greatheadii had the most diverse applications and used against 8 disease categories. • Cattle and poultry were the most dominant animals treated with Aloe species. The high diversity and occurrence of Aloe species in African landscapes often translates to their frequent utilisation for meeting the medicinal needs for human health and well-being. In addition, their value in ethnoveterinary medicine has been intermittently indicated amongst ethnic groups in Africa. This review entails a critical analysis on the ethnoveterinary uses and applications of the genus Aloe in Africa. We explored different scientific databases (Google Scholar, PubMed, Sabinet and Science Direct) to extract information from 123 eligible studies that included research articles (86.2%), dissertations/theses (9.8%), books (2.4%) and reports (1.6%). We generated an inventory of 55 Aloe species with ethnoveterinary applications across 13 African countries. Tanzania (16), South Africa (15), Kenya (14) and Ethiopia (14) had the highest number of Aloe species used for ethnoveterinary purpose. On the basis of the number of citations, A. vera (31), Aloe spp. (29), A. ferox (16) and A. secundiflora (11) were identified as the most common Aloe species with ethnoveterinary applications in Africa. The identified Aloe species were indicated as remedies against nine (9) major disease categories from the analysed literature. In terms of versatility, A. greatheadii had the most diverse applications as they were indicated as remedies for the management of eight (8) disease categories. Likewise, A. ferox, A. marlothii, Aloe spp., A. secundiflora and A. vera had multi-purpose value in ethnoveterinary medicine as they were used against seven (7) diseases/health conditions. The leaves (65.4%) and whole plant (4.7%) of Aloe species were the major plant parts used to prepare the Aloe -based herbal remedies that often targeted cattle (29.3%) and poultry/chickens (28.2%). The remedies were prepared using different methods which mainly entailed infusion (17.7%), juicing (14.2%), crushing (13.8%) and decoction (12.7%). Overall, the current review established the increasing vital role of Aloe species in treatment of animal diseases and general well-being in Africa. However, the apparent gaps (e.g., absence of plant part, diseases, animal-type, preparation and administration methods) existing in some of the assessed literature mean that deliberate efforts remain essential during ethnoveterinary surveys, to ensure the reliability and trustworthiness of the generated data. This will contribute towards the establishment of a holistic inventory/database of Aloe species with ethnoveterinary applications. Subsequent in vitro and in vivo efficacy testing of priority and valuable Aloe species with applications in ethnoveterinary medicine remain pertinent. [ABSTRACT FROM AUTHOR]

Background: Combination treatments, preferably containing an artemisinin derivative, are recommended to improve efficacy and prevent Plasmodium falciparum drug resistance. Artemether-lumefantrine (AL) and artesunateamodiaquine (AA) are efficacious regimens that have been widely adopted in sub-Saharan Africa. However, most study designs ignore the effects of these regimens on peripheral parasitaemia in the first 24 hours of therapy. The study protocol was designed to evaluate more closely the early effects and the standard measures of efficacies of these two regimens. Methods: In an open label, randomized controlled clinical trial, children aged 12 months to 132 months were randomized to receive AL (5-14 kg, one tablet; 15-24 kg, two tablets and 25-34 kg, three tablets twice daily) or artesunate (4 mg/kg daily) plus amodiaquine (10 mg/kg daily) for three days. Peripheral blood smears were made hourly in the first 4 hours, 8 h, 16 h, 24 h, and daily on days 2-7, and on days 7, 14, 21, 28, 35, and 42 for microscopic identification and quantification of Plasmodium falciparum. Results: A total of 193 children were randomized to receive either AL (97) or AA (96). In children that received both medications, early response of peripheral parasitaemia showed that 42% of children who received AL and 36.7% of those who received AA had an immediate rise in peripheral parasitaemia (0-4 h after treatment) followed by a rapid fall. The rise in parasitaemia was significant and seems to suggest a mobilization of asexual parasites from the deep tissues to the periphery. Days 3, 7, 14, 28, and 42 cure rates in the per protocol (PP) population were >90% in both groups of children. Both drug combinations were well tolerated with minimal side effects. Conclusion: The study showed the high efficacy of AL and AA in Nigerian children. In addition the study demonstrated the mobilisation of asexual parasites from the deep to the periphery in the early hours of commencing ACT treatment in a subset of patients in both study groups. It is unclear whether the early parasite dynamics discovered in this study play any role in the development of drug resistance and thus it is important to further evaluate this discovery. It may be useful for studies investigating delay in parasite clearance of artemisinin derivatives as a way of monitoring the development of resistance to artemisinin to assess the early effects of the drugs on the parasites. [ABSTRACT FROM AUTHOR]

Although, in in-vitro and limited in-vivo studies, chlorpheniramine (CP) and promethazine (PR) have each been shown to reverse chloroquine (CQ) resistance, the pharmacokinetic basis of this reversal has not been fully elucidated. In the present study, 15 healthy volunteers were randomly allotted to receive standard doses of CQ alone or in combination with CP or PR. Blood samples were collected from each volunteer at 21 time-points, from immediately before to 168 h after the initial dose. These samples were used to follow the changes in the plasma and erythrocytic concentrations of CQ. The ratio between the mean maximum CQ concentration in the erythrocytes and that in the plasma was 4.2 for the volunteers given CQ alone, 7.3 in those given CQ–CP, and 3.2 in those given CQ–PR. CP significantly enhanced the erythrocytic accumulation of CQ, increasing the maximum CQ concentration observed in the erythrocytes by 24% (P = 0.02). The bio-availability of CQ was also significantly increased in the presence of CP, with the mean value for the area under the curve, of erythrocytic concentration v. time, increasing from 99,921 to 214,516 ng/ml.h (P=0.001). The mean half-life of CQ in the erythrocytes also increased when CP was used, from 51 to 100 h, but this change was not statistically significant (P=0.83). In contrast to CP, PR had no statistically significant effect on the disposition of CQ. As CP clearly enhances disposition of CQ, a combination of CQ with CP may be useful in the management of CQ-resistant infections. Detailed toxicological studies are required to understand the full clinical implications of CP's elevation of erythrocytic CQ concentrations. [ABSTRACT FROM AUTHOR]

Background Increasing resistance to sulfadoxinepyrimethamine is leading to a decline in its effectiveness. We aimed to assess the safety profile of chlorproguanil-dapsone (CD), and to compare the safety and efficacy of this drug with that of sulfadoxine-pyrimethamine (SP) as treatment for uncomplicated falciparum malaria. Methods We undertook a double-blind, randomised trial in 1850 consecutively recruited children with uncomplicated falciparum malaria, pooling data from five African countries. Analyses were based on all randomised patients with available data. Findings CD was significantly more efficacious than SP (odds ratio 3.1 [95% CI 2.0--4.8]); 1313 patients (96%) given CD and 306 (89%) given SP achieved acceptable clinical and parasitological response by day 14. Adverse events were reported in 46% and 50% of patients randomised to CD and SP, respectively (treatment difference -4.4%, [95% CI -10.1 to 1.3]). Haemoglobin in the CD group was significantly lower than in the SP group at day 7, a difference of -4 g/L (95% CI -6 to -2). Mean day 14 haemoglobin (measured only for the small number of patients whose day 7 data caused concern) was 94 g/L (92-96) and 97 g/L (92-102) after CD and SP, respectively. Glucose-6-phosphate dehydrogenase deficient patients on CD had greater odds than those on SP of having a fall of 20 g/dL or more in haemoglobin when baseline temperature was high. Methaemoglobinaemia was seen in the CD group (n=320, mean 0.4% [95% CI 0.4-0.4]) before treatment, 4.2% (95% CI 3.8--4.6) (n=301) at day 3, and 0.6% (0.6--0.7) (n=300) at day 7). Interpretation CD had greater efficacy than SP in Africa and was well tolerated. Haematological adverse effects were more common with CD than with SP and were reversible. CD is a useful alternative where SP is failing due to resistance. [ABSTRACT FROM AUTHOR]

The coronavirus disease 2019 (COVID-19) pandemic has significant health and economic ramifications across sub-Saharan Africa (SSA). Data regarding its far-reaching impacts are severely lacking, thereby hindering the development of evidence-based strategies to mitigate its direct and indirect health consequences. To address this need, the Africa Research, Implementation Science, and Education (ARISE) Network established a mobile survey platform in SSA to generate longitudinal data regarding knowledge, attitudes, and practices (KAP) related to COVID-19 prevention and management and to evaluate the impact of COVID-19 on health and socioeconomic domains. We conducted a baseline survey of 900 healthcare workers, 1,795 adolescents 10 to 19 years of age, and 1,797 adults 20 years or older at six urban and rural sites in Burkina Faso, Ethiopia, and Nigeria. Households were selected using sampling frames of existing Health and Demographic Surveillance Systems or national surveys when possible. Healthcare providers in urban areas were sampled using lists from professional associations. Data were collected through computer-assisted telephone interviews from July to November 2020. Consenting participants responded to surveys assessing KAP and the impact of the pandemic on nutrition, food security, healthcare access and utilization, lifestyle, and mental health. We found that mobile telephone surveys can be a rapid and reliable strategy for data collection during emergencies, but challenges exist with response rates. Maintaining accurate databases of telephone numbers and conducting brief baseline in-person visits can improve response rates. The challenges and lessons learned from this effort can inform future survey efforts during COVID-19 and other emergencies, as well as remote data collection in SSA in general.

The African continent is disproportionately affected by infectious diseases. Malaria, HIV/AIDS, tuberculosis, and more "neglected" diseases including African trypanosomiasis, Buruli ulcer, leishmaniasis, onchocerciasis and trachoma continue to dramatically impact social and economic development on the continent. Health biotechnologies provide potential to develop effective strategies for the fight against the vicious circle of poverty and infections by helping in the development and improvement of novel affordable drugs, diagnostics and vaccines against these diseases. As the prospects of this emerging biotechnology research and deployment of its products become a reality in Africa, there is a need to consider the ethical, legal and social implications of both the scientific and technological advances and their use in the communities. The article provides a short overview of the potential values of biotechnology, issues involved in its transfer and presents the rationale, design and recommendations of the international workshop/symposium held in April 2005 at the International Institute for Tropical Agriculture (IITA) in Ibadan, Nigeria.

Comparing patterns of genetic variation at multiple loci in the genome of a species can potentially identify loci which are under selection. The large number of polymorphic microsatellites in the malaria parasite Plasmodium falciparum are available markers to screen for selectively important loci. The Pfs48/45 gene on Chromosome 13 encodes an antigenic protein located on the surface of parasite gametes, which is a candidate for a transmission blocking vaccine. Here, genotypic data from 255 P. falciparum isolates are presented, which show that alleles and haplotypes of five single nucleotide polymorphisms (SNPs) in the Pfs48/45 gene are exceptionally skewed in frequency among different P. falciparum populations, compared with alleles at 11 microsatellite loci sampled widely from the parasite genome. Fixation indices measuring inter-population variance in allele frequencies (F(ST)) were in the order of four to seven times higher for Pfs48/45 than for the microsatellites, whether considered (i) among populations within Africa, or (ii) among different continents. Differing mutational processes at microsatellite and SNP loci could generally affect the population structure at these different types of loci, to an unknown extent which deserves further investigation. The highly contrasting population structure may also suggest divergent selection on the amino acid sequence of Pfs48/45 in different populations, which plausibly indicates a role for the protein in determining gamete recognition and compatibility.

The Plasmodium falciparum erythrocyte binding antigen-175 gene (eba-175) has highly divergent allelic segments (Cseg and Fseg) in one part of the gene (region III), but only a small number of single nucleotide polymorphisms (SNPs) in the rest of the sequence. Here, evidence for the possible importance of the Cseg/Fseg dimorphism was sought in a molecular population genetic analysis of the gene. First, allele frequency distributions were determined for the Cseg/Fseg dimorphism and five SNPs in a sample of five populations in Africa. The inter-population variance in frequencies was higher for Cseg/Fseg (F(ST)=0.18) than for the SNPs (F(ST) values from 0.03 to 0.10), but these values were entirely dependent on the inclusion of one particularly divergent population (Sudan). Second, linkage disequilibrium was measured among the intragenic loci. There was the expected trend of declining linkage disequilibrium with increasing molecular distance, but it is notable that the Cseg allele was in absolute linkage disequilibrium with the two flanking SNPs, whereas the Fseg allele was associated with a broader range of SNP haplotypes. Finally, there was no association between the Cseg/Fseg alleles of eba-175 in parasites and the M/N alleles of the glycophorin A erythrocyte receptor in the human subjects.

The Malaria Research and Reference Reagent Resource Center (MR4) is a program to support the international malaria research community. The primary goal is to improve access to well-characterized quality-controlled parasite, host and vector reagents for standardization of assays and other general research purposes. MR4 is open to all scientists worldwide, however many of its inaugural activities will have a focus in Africa, where the concept for the MR4 was born. Reagents are donated to the MR4 Center by malaria researchers and their institutions for distribution to other investigators special arrangements are also possible for developing reagents in-house, or for coordinating reagents for multi-site studies. In addition to providing reagents, the MR4 also aims to promotoe technology transfer and to foster scientific exchange between new and established malaria researchers. This will be done via workshops, training programs, and dissemination of information (electronic and hard copy). Suggestions for reagents, information resources, or training opportunities are welcome from the research community to make this a responsive, service-oriented program.

The origin and geographical spread of Plasmodium falciparum is here determined by analysis of mitochondrial DNA sequence polymorphism and divergence from its most closely related species P. reichenowi (a rare parasite of chimpanzees). The complete 6 kb mitochondrial genome was sequenced from the single known isolate of P. reichenowi and from four different cultured isolates of P. falciparum, and aligned with the two previously derived P. falciparum sequences. The extremely low synonymous nucleotide polymorphism in P. falciparum (pi=0.0004) contrasts with the divergence at such sites between the two species (kappa=0.1201), and supports a hypothesis that P. falciparum has recently emerged from a single ancestral population. To survey the geographical distribution of mitochondrial haplotypes in P. falciparum, 104 isolates from several endemic areas were typed for each of the identified single nucleotide polymorphisms. The haplotypes show a radiation out of Africa, with unique types in Southeast Asia and South America being related to African types by single nucleotide changes. This indicates that P. falciparum originated in Africa and colonised Southeast Asia and South America separately.

New strategies are required to identify the most important targets of protective immunity in complex eukaryotic pathogens. Natural selection maintains allelic variation in some antigens of the malaria parasite Plasmodium falciparum. Analysis of allele frequency distributions could identify the loci under most intense selection. The merozoite surface protein 1 (Msp1) is the most-abundant surface component on the erythrocyte-invading stage of P. falciparum. Immunization with whole Msp1 has protected monkeys completely against homologous and partially against non-homologous parasite strains. The single-copy msp1 gene, of about 5 kilobases, has highly divergent alleles with stable frequencies in endemic populations. To identify the region of msp1 under strongest selection to maintain alleles within populations, we studied multiple intragenic sequence loci in populations in different regions of Africa and Southeast Asia. On both continents, the locus with the lowest inter-population variance in allele frequencies was block 2, indicating selection in this part of the gene. To test the hypothesis of immune selection, we undertook a large prospective longitudinal cohort study. This demonstrated that serum IgG antibodies against each of the two most frequent allelic types of block 2 of the protein were strongly associated with protection from P. falciparum malaria.

Malaria parasites are sexually reproducing protozoa, although the extent of effective meiotic recombination in natural populations has been debated. If meiotic recombination occurs frequently, compared with point mutation and mitotic rearrangement, linkage disequilibrium between polymorphic sites is expected to decline with increasing distance along a chromosome. The rate of this decline should be proportional to the effective meiotic recombination rate in the population. Multiple polymorphic sites covering a 5-kb region of chromosome 9 (the msp1 gene) have been typed in 547 isolates from six populations in Africa to test for such a decline and estimate its rate in populations of Plasmodium falciparum. The magnitude of two-site linkage disequilibrium declines markedly with increasing molecular map distance between the sites, reaching nonsignificant levels within a map range of 0.3-1.0 kb in five of the populations and over a larger map distance in the population with lowest malaria endemicity. The rate of decline in linkage disequilibrium over molecular map distance is at least as rapid as that observed in most chromosomal regions of other sexually reproducing eukaryotes, such as humans and Drosophila. These results are consistent with the effective recombination rate expected in natural populations of P. falciparum, predicted on the basis of the underlying molecular rate of meiotic crossover and the coefficient of inbreeding caused by self-fertilization events. This is conclusive evidence to reject any hypothesis of clonality or low rate of meiotic recombination in P. falciparum populations. Moreover, the data have major implications for the design and interpretation of population genetic studies of selection on P. falciparum genes.