The Dantu blood group prevents parasite growth in vivo: Evidence from a controlled human malaria infection study

Background: The long co-evolution of Homo sapiens and Plasmodium falciparum has resulted in the selection of numerous human genetic variants that confer an advantage against severe malaria and death. One such variant is the Dantu blood group antigen, which is associated with 74% protection against severe and complicated P. falciparum malaria infections in homozygous individuals, similar to that provided by the sickle haemoglobin allele (HbS). Recent in vitro studies suggest that Dantu exerts this protection by increasing the surface tension of red blood cells, thereby impeding the ability of P. falciparum merozoites to invade them and reducing parasite multiplication. However, no studies have yet explored this hypothesis in vivo. Methods: We investigated the effect of Dantu on early phase P. falciparum (Pf) infections in a controlled human malaria infection (CHMI) study. 141 sickle-negative Kenyan adults were inoculated with 3.2 × 103 aseptic, purified, cryopreserved Pf sporozoites (PfSPZ Challenge) then monitored for blood-stage parasitaemia for 21 days by quantitative polymerase chain reaction (qPCR)analysis of the 18S ribosomal RNA P. falciparum gene. The primary endpoint was blood-stage P. falciparum parasitaemia of ≥500/μl while the secondary endpoint was the receipt of antimalarial treatment in the presence of parasitaemia of any density. On study completion, all participants were genotyped both for Dantu and for four other polymorphisms that are associated with protection against severe falciparum malaria: α+-thalassaemia, blood group O, G6PD deficiency, and the rs4951074 allele in the red cell calcium transporter ATP2B4. Results: The primary endpoint was reached in 25/111 (22.5%) non-Dantu subjects in comparison to 0/27 (0%) Dantu heterozygotes and 0/3 (0.0%) Dantu homozygotes (p=0.01). Similarly, 49/111 (44.1%) non-Dantu subjects reached the secondary endpoint in comparison to only 7/27 (25.9%) and 0/3 (0.0%) Dantu heterozygotes and homozygotes, respectively (p=0.021). No significant impacts on either outcome were seen for any of the other genetic variants under study. Conclusions: This study reveals, for the first time, that the Dantu blood group is associated with high-level protection against early, non-clinical, P. falciparum malaria infections in vivo. Learning more about the mechanisms involved could potentially lead to new approaches to the prevention or treatment of the disease. Our study illustrates the power of CHMI with PfSPZ Challenge for directly testing the protective impact of genotypes previously identified using other methods

Food Prices: Eastern and Southern Africa Defy Global Trends

Global food prices started rising sharply in 2006 and reached record levels in the second quarter of 2008. Although domestic food prices in Eastern and Southern Africa (ESA) are not totally unrelated to world prices, a study by the Association for Strengthening Agricultural Research in East and Central Africa (ASARECA), the Regional Strategic and Knowledge Support System for Eastern and Central Africa (ReSAKSS-ECA), and the Consultative Group on International Agricultural Research (CGIAR) Alliance shows that national and regional factors are very important in driving domestic food prices. While global food prices have exhibited declining trends since June 2008, several ESA countries have experienced increasing prices in 2008 and early 2009. The price surges appear to be further fuelled by some of the policy responses that countries have employed in their attempts to address the food price problem. This brief provides an update on food price trends in ESA. It starts by comparing the Food and Agricultural Organization of the United Nations (FAO) global food price index and food price indexes (FPI) in individual countries followed by an update on price trends for specifi c commodities. This information serves to remind policymakers that the easing global food prices do not present any immediate relief to the food crises facing their individual countries

Status and Trends of Agricultural and Rural Development Indicators in the COMESA Region

This report is divided into eight sections, section one provides an introduction about the COMESA region and the structure of the economy in the region. Section two presents trends of various socioeconomic indicators in the region. Section three contains gender related information while section four focuses on food security in COMESA. Some examples of subnational food security situations are also given here. Section five focuses on various indicators related to agriculture in COMESA including agriculture and food production, input utilization in agriculture, and application of irrigation in agriculture. Section six provides information on expenditures in agriculture and agricultural value addition in the region. In section seven, various indicators on trade are reviewed. The last section, section eight, contains summary, conclusions, and policy recommendations

Paraoxonase1 Genetic Polymorphisms in a Mixed Ancestry African Population

Paraoxonase 1 (PON1) activity is markedly influenced by coding polymorphisms, Q/R at position 192 and M/L at position 55 of the PON1 gene. We investigated the frequencies of these polymorphisms and their effects on PON1 and antioxidant activities in 844 South African mixed ancestry individuals. Genotyping was done using allele-specific TaqMan technology, PON1 activities were measured using paraoxon and phenylacetate, oxidative status was determined by measuring the antioxidant activities of ferric reducing antioxidant power and trolox equivalent antioxidant capacity, and lipid peroxidation markers included malondialdehyde and oxidized LDL. The frequencies of Q192R and L55M were 47.6% and 28.8%, respectively, and the most common corresponding alleles were 192R (60.4%) and 55M (82.6%). The Q192 was significantly associated with 5.8 units’ increase in PON1 concentration and 15.4 units’ decrease in PONase activity after adjustment for age, sex, BMI, and diabetes, with suggestion of differential effects by diabetes status. The PON1 L55 variant was associated with none of the measured indices. In conclusion, we have shown that the Q192R polymorphism is a determinant of both PON1 concentration and activity and this association appeared to be enhanced in subjects with diabetes

Attempts to identify Cassava Brown Streak Virus in western Democratic Republic of Congo

Open Access ArticleRoot necrosis similar to those of the cassava brown streak disease (CBSD) were observed on cassava in western provinces of the Democratic Republic of Congo (DR.Congo) in the early 2000’s. However molecular laboratory diagnosis were not able to detect any causative agent responsible for the attacks, hence, the disease related to these symptoms was named CBSD-like disease. In order to assess the distribution and the incidence of the CBSD-like disease, surveys were carried out in four western provinces, comprising, Kwango and Kwilu, Sud Ubangi, Kinshasa and Kongo Central. CBSD-like disease was observed in all surveyed provinces on the basis of root symptoms because foliar symptoms were different to those of the documented cases of CBSD in other parts of east Africa. CBSD-like disease incidence was high in Kongo Central and Sud Ubangi, exceeding an average of 50 %, but low in Kwango and Kwilu (32.8%) and in Kinshasa (19.1%). During the surveys, cassava leaf samples were collected for lab identification of the causal agent. PCR diagnosis was done on these samples using primers specific for the two known CBSVs. All samples tested negative with no amplification of DNA fragments of the correct size. Thus, further analysis on the causative organism is needed using Next Generation Sequencing (NGS) approaches. NGS approaches will help also to identify the causative organism in other Central Africa countries (Angola, Congo-Brazzaville and Gabon) where such cassava root necrosis have been reported or are suspected

Perceived risks of infection, hospitalization, and death from COVID-19 at the Equator: Ecuador and Kenya

Objectives: This study''s goal was to determine the perceived risks of infection as well as the perceived risks of hospitalization and death from COVID-19 in Ecuador and Kenya. It also assessed the factors associated with the risk-related perceptions. Methods: Cross-sectional studies with samples from the adult populations in both countries were conducted to assess the perceived risks of contracting COVID-19. Data were collected online using the Qualtrics platform from samples of 1, 050 heads of households ages 18 years or older in each country. Three statistical analyses were conducted: summary statistics, correlation, and linear regression. Results: The average perceived risks of COVID-19 infection, hospitalization, and death in the Kenyan sample were 27.1%, 43.2%, and 17.2%, respectively, and the values for the Ecuadorian sample were 34%, 32.8%, and 23.3%, respectively. The Pearson''s correlation coefficients between the risk measures in each country were less than 0.38. Risk measures were associated with several sociodemographic variables (e.g., income, gender, location) but not age. Conclusions: The perceived risks of COVID-19 infection, hospitalization, and death in Kenya and Ecuador were significantly higher relative to the statistics reported; however, no strong association existed between perceived risk and age, which is a key factor in adverse health outcomes, including death, among COVID-19 infected individuals

The impact of non-tariff barriers on maize and beef trade in East Africa

On March 2, 2004, the East African Community (EAC) member states signed the protocol for the establishment of the East African Community Customs Union, which commits them, among others, to eliminate non-tariff barriers (NTBs) to increase intraregional trade. However, several NTBs are still applied by member states, raising concerns among policy makers and the business community. There is, however, no information about the magnitude of the impact of these NTBs. This study identifies the existing NTBs on maize and beef trade in East Africa and quantifies their impact on trade and the welfare of EAC citizens using a Spatial Equilibrium Model (SEM). Data on NTBs were collected from traders and transporters of maize and beef cattle in East Africa. In addition, the study found that the main types of NTBs within the three founding members of the EAC (Kenya, Tanzania and Uganda) are similar. They include administrative requirements (mainly licenses, municipal and council permits), taxes/duties (mainly excise and cess duty), roadblocks, customs barriers, weighbridges, licensing, corruption (e.g., through bribes) and transiting. The results of the welfare analysis vary across the three countries, but the net monetary gains are positive in all cases. A complete abolishment or a reduction of the existing NTBs in maize and beef trade increases intra-EAC maize and beef trade flows, with Kenya importing more maize from both Uganda and Tanzania, while Uganda’s beef exports to Kenya and Tanzania increase. As a result, positive net welfare gains are attained for the entire EAC maize and beef sub-sectors. In all cases, those who gain from the proposed reductions in NTBs can potentially compensate the losers, leading to potential improvements in welfare. These findings give compelling evidence in support of the elimination of NTBs within the EAC customs union. The study recommends taking a regional approach to eliminating the existing NTBs since they are similar across the member countries and across commodities so as to exploit economies of scale. Other policy recommendations include streamlining of administrative procedures at border points to improve efficiency, and speeding up the implementation of procedures at point of origin and at the border points. Finally, the study recommends the need to design and implement monitoring systems to provide feedback to the relevant authorities on the implementation of measures to remove unnecessary barriers to trade within the EAC region