scholarly journals Can changes in malaria transmission intensity explain prolonged protection and contribute to high protective efficacy of intermittent preventive treatment for malaria in infants?

2008 ◽  
Vol 7 (1) ◽  
Author(s):  
Roly D Gosling ◽  
Azra C Ghani ◽  
Jaqueline L Deen ◽  
Lorenz von Seidlein ◽  
Brian M Greenwood ◽  
...  
Keyword(s):  
Malaria Transmission ◽  
Protective Efficacy ◽  
Intermittent Preventive Treatment ◽  
Preventive Treatment ◽  
Transmission Intensity ◽  
Malaria Transmission Intensity

Temporal Dynamics of Malaria Transmission in Two Rural Areas of Burkina Faso With Two Ecological Differences

2010 ◽  
Vol 47 (4) ◽  
pp. 618-624 ◽  
Author(s):  
Ilboudo-Sanogo Edith ◽  
Tiono B. Alfred ◽  
Sagnon N′falé ◽  
Cuzin Ouattara Nadine ◽  
Nébié Issa ◽  
...  
Keyword(s):  
Burkina Faso ◽  
Malaria Transmission ◽  
Rural Areas ◽  
Temporal Dynamics ◽  
Vaccine Trial ◽  
Anopheles Funestus ◽  
Clinical Malaria ◽  
Transmission Intensity ◽  
Artificial Lake ◽  
Malaria Transmission Intensity

Abstract To determine the relationship between malaria transmission intensity, clinical malaria, immune response, plasmodic index, and to furthermore characterize a malaria vaccine trial site for potential malaria vaccines candidate testing, a study was conducted in Tensobtenga and Balonguen, two villages in Burkina Faso characterized by different malaria transmission levels. The study villages are located in a Sudan savanna area. Malaria transmission is seasonal and peaks in September in these villages. Tensobtenga and Balonguen are comparables in all aspects, except the presence of an artificial lake and wetlands in Tensobtenga. The mosquitoes sampling sites were randomly selected, taking into consideration the number of potential breeding sites, and the number of households in each village. Three times a week during 12 mo mosquitoes were collected by the Center for Disease Control and Prevention light traps in sentinel sites. To assess the infectivity the mosquitoes double ELISAs tests were performed on thoraces of female Anopheles gambiae s.l. (Giles) and Anopheles funestus. A total of 54,392 female Anopheles, representing 92.71% of the total mosquitoes, were collected. The peaks of aggressiveness because of either An. gambiae s.l. or An. funestus were observed in September in each of the villages. However, these peaks were lower in Balonguen compared with Tensobtenga. Malaria cumulative aggressiveness and transmission intensity because of both species peaked in September in each of the two villages, with lower values in Balonguen in comparison to Tensobtenga. From February to May, malaria transmission intensity is negligible in Balonguen and <1 bite/person/mo is observed in Tensobtenga. These results have confirmed the marked seasonality of malaria transmission in the study area.

scholarly journals Molecular characterization of Plasmodium falciparum PHISTb proteins as potential targets of naturally-acquired immunity against malaria

2020 ◽  
Vol 5 ◽  
pp. 136
Author(s):  
Tony I. Isebe ◽  
Joel L. Bargul ◽  
Bonface M. Gichuki ◽  
James M. Njunge ◽  
James Tuju ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Malaria Transmission ◽  
The Gambia ◽  
Antibody Responses ◽  
Transmission Intensity ◽  
Parasite Development ◽  
Natural Immunity ◽  
Malaria Transmission Intensity ◽  
Transmission Region ◽  
Antibody Levels

Background: Plasmodium falciparum causes the deadliest form of malaria in humans. Upon infection, the host’s infected red blood cells (iRBCs) are remodelled by exported parasite proteins in order to provide a niche for parasite development and maturation. Methods: Here we analysed the role of three PHISTb proteins Pf3D7_0532400, Pf3D7_1401600, and Pf3D7_1102500 by expressing recombinant proteins and evaluated antibody responses against these proteins using immune sera from malaria-exposed individuals from Kenya and The Gambia in Africa. Results: Our findings show that children and adults from malaria-endemic regions recognized the three PHISTb proteins. Responses against the PHISTb proteins varied with malaria transmission intensity in three different geographical sites in Kenya (Siaya and Takaungu) and The Gambia (Sukuta). Antibody responses against PHISTb antigens Pf3D7_1102500 and Pf3D7_1401600 were higher in Sukuta, a low transmission region in the Gambia, as compared to Siaya, a high transmission region in western Kenya, unlike Pf3D7_0532400. Anti-PHIST responses show a negative correlation between antibody levels and malaria transmission intensity for two PHIST antigens, Pf3D7_1102500 and Pf3D7_1401600. However, we report a correlation in antibody responses between schizont extract and Pf3D7_0532400 (p=0.00582). Acquisition of anti-PHIST antibodies was correlated with exposure to malaria for PHISTb protein Pf3D7_0532400 (p=0.009) but not the other PHIST antigens Pf3D7_1102500 and Pf3D7_1401600 (p=0.507 and p=0.15, respectively, CI=95%). Children aged below 2 years had the lowest antibody levels, but the responses do not correlate with age differences. Conclusions: Collectively, these findings provide evidence of natural immunity against PHISTb antigens that varies with level of malaria exposure and underscore potential for these parasite antigens as possible serological markers to P. falciparum infection aimed at contributing to malaria control through vaccine development.

scholarly journals Diversity of KIR genes and their HLA-C ligands in Ugandan populations with historically varied malaria transmission intensity

2021 ◽  
Author(s):  
Stephen Tukwasibwe ◽  
James A. Traherne ◽  
Olympe Chazara ◽  
Jyothi Jayaraman ◽  
John Trowsdale ◽  
...  
Keyword(s):  
Infectious Diseases ◽  
Malaria Transmission ◽  
Real Time ◽  
High Throughput ◽  
Real Time Pcr ◽  
Association Studies ◽  
Transmission Intensity ◽  
Malaria Transmission Intensity ◽  
Significant Difference ◽  
Pcr Method

Abstract Background: Malaria is one of the most serious infectious diseases in the world. The malaria burden is greatly affected by human immunity, and immune responses vary between populations. Genetic diversity in KIR and HLA-C genes, which are important in immunity to infectious diseases, is likely to play a role in this heterogeneity. Several studies have shown that KIR and HLA-C genes influence the immune response to viral infections, but few studies have examined the role of KIR and HLA-C in malaria infection, and these have used low-resolution genotyping. The aim of this study was to determine whether genetic variation in KIR and their HLA-C ligands differ in Ugandan populations with historically varied malaria transmission intensity using more comprehensive genotyping approaches.Methods: High throughput multiplex quantitative real-time PCR method was used to genotype KIR genetic variants and copy number variation and a high-throughput real-time PCR method was developed to genotype HLA-C1 and C2 allotypes for 1,344 participants, aged 6 months to 10 years, enrolled from Ugandan populations with historically high (Tororo District), medium (Jinja District) and low (Kanungu District) malaria transmission intensity. Results: The prevalence of KIR3DS1, KIR2DL5, KIR2DS5 and KIR2DS1 genes was significantly lower in populations from Kanungu compared to Tororo (7.6% vs. 13.2%: p=0.006, 57.2% vs. 66.4%: p=0.005, 33.2% vs. 46.6%: p<0.001 and 19.7% vs. 26.7%: p=0.014 respectively) or Jinja (7.6% vs.18.1%: p<0.001, 57.2% vs. 63.8%: p=0.048, 33.2% vs. 43.5%: p=0.002 and 19.7% vs. 30.4%: p<0.001 respectively). The prevalence of homozygous HLA-C2 was significantly higher in populations from Kanungu (31.6%) compared to Jinja (21.4%), p=0.043, with no significant difference between Kanungu and Tororo (26.7%), p=0.296. Conclusions: The KIR3DS1, KIR2DL5, KIR2DS5 and KIR2DS1 genes may partly explain differences in transmission intensity of malaria since these genes have been positively selected for in places with historically high malaria transmission intensity. The high-throughput multiplex real-time HLA-C genotyping PCR method developed will be useful in disease association studies involving large cohorts.

scholarly journals Spatio-temporal variation in malaria transmission intensity in five agro-ecosystems in Mvomero district, Tanzania

2010 ◽  
Vol 4 (2) ◽  
pp. 167 ◽  
Author(s):  
Leonard E. G. Mboera ◽  
Kesheni P. Senkoro ◽  
Benjamin K. Mayala ◽  
Susan F. Rumisha ◽  
Rwehumbiza T. Rwegoshora ◽  
...  
Keyword(s):  
Temporal Variation ◽  
Malaria Transmission ◽  
Transmission Intensity ◽  
Malaria Transmission Intensity ◽  
Spatio Temporal

scholarly journals Associations between Malaria-Preventive Regimens and Plasmodium falciparum Drug Resistance-Mediating Polymorphisms in Ugandan Pregnant Women

2020 ◽  
Vol 64 (12) ◽  
Author(s):  
Patience Nayebare ◽  
Victor Asua ◽  
Melissa D. Conrad ◽  
Richard Kajubi ◽  
Abel Kakuru ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Genetic Polymorphisms ◽  
Protective Efficacy ◽  
Intermittent Preventive Treatment ◽  
Preventive Treatment ◽  
Drug Susceptibility ◽  
Recent Trial ◽  
Content Type ◽  
High Level ◽  
Selection Of

ABSTRACT Intermittent preventive treatment in pregnancy (IPTp) with monthly sulfadoxine-pyrimethamine (SP) is recommended for malaria-endemic parts of Africa, but efficacy is compromised by resistance, and, in recent trials, dihydroartemisinin-piperaquine (DP) has shown better antimalarial protective efficacy. We utilized blood samples from a recent trial to evaluate selection by IPTp with DP or SP of Plasmodium falciparum genetic polymorphisms that alter susceptibility to these drugs. The prevalence of known genetic polymorphisms associated with altered drug susceptibility was determined in parasitemic samples, including 375 collected before IPTp drugs were administered, 125 randomly selected from those receiving SP, and 80 from those receiving DP. For women receiving DP, the prevalence of mixed/mutant sequences was greater in samples collected during IPTp than that in samples collected prior to the intervention for PfMDR1 N86Y (20.3% versus 3.9%; P < 0.001), PfMDR1 Y184F (73.0% versus 53.0%; P < 0.001), and PfCRT K76T (46.4% versus 24.0%; P < 0.001). Considering SP, prior to IPTp, the prevalence of all 5 common antifolate mutations was over 92%, and this prevalence increased following exposure to SP, although none of these changes were statistically significant. For two additional mutations associated with high-level SP resistance, the prevalence of PfDHFR 164L (13.7% versus 4.0%; P = 0.004), but not PfDHPS 581G (1.9% versus 3.0%; P = 0.74), was greater in samples collected during IPTp compared to those collected before the intervention. Use of IPTp in Uganda selected for parasites with mutations associated with decreased susceptibility to IPTp regimens. Thus, a potential drawback of IPTp is selection of parasites with decreased drug susceptibility.

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