Agricultural Efficiency Gains and Trade Liberalization in Sudan

The traditional agriculture in Sudan occupies 60% of the total cultivated land and employs 65% of the agricultural population. Nevertheless, it is characterized by its low crop productivity, which is mainly driven by low technical efficiency, while drought and civil conflicts threaten most of its areas countrywide. Therefore, it has contributed only an average of 16% to the total agricultural GDP during the last decade. This paper addresses from an empirical point of view the sectoral and macroeconomic implications of agricultural efficiency improvement in Sudan and assesses the efficiency gains under the assumption of trade liberalization. Efficiency improvement experiments are implemented by augmenting the efficiency parameters of labor, capital, and land in a Computable General Equilibrium (CGE) framework. The CGE model of the study relies on the newly produced Sudanese Social Accounting Matrix (SAM), which provides data on 10 agricultural sectors, 10 industrial sectors and 13 service sectors. Results show that improving the agricultural efficiency would lead to improvements in GDP, welfare level, and trade balance. In addition it would also improve the output and competitiveness of the Sudanese agricultural exports and increase their strength to face the challenges of liberalization.Agricultural efficiency, liberalization, Sudan SAM, CGE analysis, Agribusiness, Agricultural and Food Policy, Agricultural Finance, Consumer/Household Economics, Crop Production/Industries, Food Security and Poverty, Labor and Human Capital, Land Economics/Use, Production Economics, Productivity Analysis, D2, D5, D6, E1, E2, F1, F2, H2,

Seasonal variation in agglutination of Plasmodium falciparum-infected erythrocytes

Abstract. Agglutination and rosette formation are in vitro characteristics of Plasmodium falciparum–infected erythrocytes, which have been associated with host protective immune responses and also with parasite virulence. The present study was carried out in an area of seasonal and unstable malaria transmission in eastern Sudan. Plasma samples were obtained before, during, and after the transmission season from a volunteer cohort of 64 individuals seven years of age and older. These plasmas were assayed for their ability to agglutinate cultured parasitized eryth-rocytes originally obtained from acute malaria infection samples taken from five of the cohort members. Our data show that the capacity of donor plasma samples to agglutinate parasitized cells depended largely on the time of sampling relative to the transmission season, at least within this epidemiologic setting. Thus, although less than half of the pretransmission season samples could agglutinate any of the five lines of cultured parasites, all post-transmission season samples could agglutinate at least one of the parasite lines, with 74 % agglutinating two or more lines. This increase in the agglutination capacity of individual plasma samples after the transmission season occurred essentially regardless of whether an individual had experienced a clinical malaria attack during the transmission season. The study thus confirms the acquisition of agglutinating antibodies following episodes of clinical malaria, but also dem-onstrates that such acquisition can take place in the absence of disease, presumably as a consequence of subclinica

Genotyping of Plasmodium falciparum infections by PCR: a comparative multicentre study

Genetic diversity of malaria parasites represents a major issue in understanding several aspects of malaria infection and disease. Genotyping of Plasmodium falciparum infections with polymerase chain reaction (PCR)-based methods has therefore been introduced in epidemiological studies. Polymorphic regions of the msp1, msp2 and glurp genes are the most frequently used markers for genotyping, but methods may differ. A multicentre study was therefore conducted to evaluate the comparability of results from different laboratories when the same samples were analysed. Analyses of laboratory-cloned lines revealed high specificity but varying sensitivity. Detection of low-density clones was hampered in multiclonal infections. Analyses of isolates from Tanzania and Papua New Guinea revealed similar positivity rates with the same allelic types identified. The number of alleles detected per isolate, however, varied systematically between the laboratories especially at high parasite densities. When the analyses were repeated within the laboratories, high agreement was found in getting positive or negative results but with a random variation in the number of alleles detected. The msp2 locus appeared to be the most informative single marker for analyses of multiplicity of infection. Genotyping by PCR is a powerful tool for studies on genetic diversity of P. falciparum but this study has revealed limitations in comparing results on multiplicity of infection derived from different laboratories and emphasizes the need for highly standardized laboratory protocol

Agricultural Efficiency Gains and Trade Liberalization in Sudan

The traditional agriculture in Sudan occupies 60% of the total cultivated land and employs 65% of the agricultural population. Nevertheless, it is characterized by its low crop productivity, which is mainly driven by low technical efficiency, while drought and civil conflicts threaten most of its areas countrywide. Therefore, it has contributed only an average of 16% to the total agricultural GDP during the last decade. This paper addresses from an empirical point of view the sectoral and macroeconomic implications of agricultural efficiency improvement in Sudan and assesses the efficiency gains under the assumption of trade liberalization. Efficiency improvement experiments are implemented by augmenting the efficiency parameters of labor, capital, and land in a Computable General Equilibrium (CGE) framework. The CGE model of the study relies on the newly produced Sudanese Social Accounting Matrix (SAM), which provides data on 10 agricultural sectors, 10 industrial sectors and 13 service sectors. Results show that improving the agricultural efficiency would lead to improvements in GDP, welfare level, and trade balance. In addition it would also improve the output and competitiveness of the Sudanese agricultural exports and increase their strength to face the challenges of liberalization

The role of asymptomatic P. falciparum parasitaemia in the evolution of antimalarial drug resistance in areas of seasonal transmission

In areas with seasonal transmission, proper management of acute malaria cases that arise in the transmission season can markedly reduce the disease burden. However, asymptomatic carriage of Plasmodium falciparum sustains a long-lasting reservoir in the transmission-free dry season that seeds cyclical malaria outbreaks. Clinical trials targeting asymptomatic parasitaemia in the dry season failed to interrupt the malaria epidemics that follow annual rains. These asymptomatic infections tend to carry multiple-clones, capable of producing gametocytes and infecting Anopheles mosquitoes. Different clones within an infection fluctuate consistently, indicative of interaction between clones during the long course of asymptomatic carriage. However, the therapy-free environment that prevails in the dry season dis-advantages the drug resistant lineages and favors the wild-type parasites. This review highlights some biological and epidemiological characteristics of asymptomatic parasitaemia and calls for consideration of polices to diminish parasite exposure to drugs “therapy-free” and allow natural selection to curb drug resistance in the above setting

Genetic recombination in field populations of Plasmodium falciparum

Malaria parasites undergo a mainly haploid life-cycle. The only diploid stage is the zygote, formed by fusion of gametes in the mosquito stomach. The first division of the zygote is a meiotic one, producing, after further mitotic divisions, haploid sporozoites. Genetic recombination occurs at meiosis, following cross-fertilization of gametes of parasites with different genotypes. This has been shown in laboratory studies by feeding mosquitoes on a mixture of Plasmodium falciparum clones and analyzing the resulting progeny for parasites with non-parental combinations of the clone markers. Such recombinants are produced at a higher than expected frequency. There is considerable genotype diversity in field populations of P. falciparum. Evidence that recombination in mosquitoes is the principal cause of this diversity is two-fold. First, parasites isolated from patients in small isolated communities at the same time are genetically very diverse. No two isolates examined for polymorphic markers at some 20 loci have been found to possess identical combinations of the allelic variants of these genes. Second, examination of oocysts in wild-caught mosquitoes by the PCR technique has shown that a high proportion are heterozygotes. There is thus frequent crossing in natural populations of this parasite. In addition to recombination at meiosis, it is also clear that genetic changes can occur during asexual multiplication of P. falciparum blood forms, as shown by deletions of regions of certain chromosomes during in vitro culture. The extent to which this occurs in nature is not known

Genetic recombination in field populations of Plasmodium falciparum

Malaria parasites undergo a mainly haploid life-cycle. The only diploid stage is the zygote, formed by fusion of gametes in the mosquito stomach. The first division of the zygote is a meiotic one, producing, after further mitotic divisions, haploid sporozoites. Genetic recombination occurs at meiosis, following cross-fertilization of gametes of parasites with different genotypes. This has been shown in laboratory studies by feeding mosquitoes on a mixture of Plasmodium falciparum clones and analyzing the resulting progeny for parasites with non-parental combinations of the clone markers. Such recombinants are produced at a higher than expected frequency. There is considerable genotype diversity in field populations of P. falciparum. Evidence that recombination in mosquitoes is the principal cause of this diversity is two-fold. First, parasites isolated from patients in small isolated communities at the same time are genetically very diverse. No two isolates examined for polymorphic markers at some 20 loci have been found to possess identical combinations of the allelic variants of these genes. Second, examination of oocysts in wild-caught mosquitoes by the PCR technique has shown that a high proportion are heterozygotes. There is thus frequent crossing in natural populations of this parasite. In addition to recombination at meiosis, it is also clear that genetic changes can occur during asexual multiplication of P. falciparum blood forms, as shown by deletions of regions of certain chromosomes during in vitro culture. The extent to which this occurs in nature is not known

Characteristics of Plasmodium falciparum parasites that survive the lengthy dry season in eastern Sudan where malaria transmission is markedly seasonal

We have examined 83 inhabitants of Asar village in eastern Sudan, where malaria transmission lasts approximately 2-3 months each year, for the presence of Plasmodium falciparum during the prolonged dry season. All patients were treated with a standard dose of chloroquine following the first diagnosis, then examined by microscopy and the polymerase chain reaction (PCR) every two weeks for the first two months and subsequently once each month for the next 15 months throughout the dry season until the following transmission season. The PCR primers used amplified polymorphic regions of the merozoite surface protein-1 (MSP-1), MSP-2, and glutamate-rich protein genes. Results show that subpatent and asymptomatic parasitemias persisted in some patients for several months throughout the dry season, often as genetically complex infections. Different genotypes could coexist together in a single infection and the proportions of each could fluctuate dramatically during this period. However, in some individuals, single genotypes appeared to persist for several months. Reappearance of clinical symptoms among patients with chronic infections was often associated with appearance of new alleles, indicating reinfections with parasites of novel genotypes

Characteristics of Plasmodium falciparum parasites that survive the lengthy dry season in eastern Sudan where malaria transmission is markedly seasonal

We have examined 83 inhabitants of Asar village in eastern Sudan, where malaria transmission lasts approximately 2-3 months each year, for the presence of Plasmodium falciparum during the prolonged dry season. All patients were treated with a standard dose of chloroquine following the first diagnosis, then examined by microscopy and the polymerase chain reaction (PCR) every two weeks for the first two months and subsequently once each month for the next 15 months throughout the dry season until the following transmission season. The PCR primers used amplified polymorphic regions of the merozoite surface protein-1 (MSP-1), MSP-2, and glutamate-rich protein genes. Results show that subpatent and asymptomatic parasitemias persisted in some patients for several months throughout the dry season, often as genetically complex infections. Different genotypes could coexist together in a single infection and the proportions of each could fluctuate dramatically during this period. However, in some individuals, single genotypes appeared to persist for several months. Reappearance of clinical symptoms among patients with chronic infections was often associated with appearance of new alleles, indicating reinfections with parasites of novel genotypes