A reduction in malaria transmission intensity in Northern Ghana after 7 years of indoor residual spraying

Abstract Background Long-lasting insecticidal nets (LLINs) and indoor residual spraying of insecticide (IRS) are widely recommended for the prevention of malaria in endemic regions. Data from human landing catches provide information on the impact of vector control on vector populations. Here, malaria transmission indoors and outdoors, before and after mass deployment of LLINs and IRS in Uganda was compared. Methods The study took place in Tororo district, a historically high transmission area where universal LLIN distribution was conducted in November 2013 and May 2017 and 6 rounds of IRS implemented from December 2014 to July 2018. Human landing catches were performed in 8 houses monthly from October 2011 to September 2012 (pre-intervention period) and every 4 weeks from November 2017 to October 2018 (post-intervention period). Mosquitoes were collected outdoors from 18:00 to 22:00 h and indoors from 18:00 to 06:00 h. Female Anopheles were tested for the presence of Plasmodium falciparum sporozoites and species identification performed using gross dissection and polymerase chain reaction (PCR). Results The interventions were associated with a decline in human biting rate from 19.6 to 2.3 female Anopheles mosquitoes per house per night (p < 0.001) and annual entomological inoculation rate from 129 to 0 infective bites per person per year (p < 0.001). The proportion of mosquitoes collected outdoors increased from 11.6 to 49.4% (p < 0.001). Prior to the interventions the predominant species was Anopheles gambiae sensu stricto (s.s.), which comprised an estimated 76.7% of mosquitoes. Following the interventions, the predominant species was Anopheles arabiensis, which comprised 99.5% of mosquitoes, with almost complete elimination of An. gambiae s.s. (0.5%). Conclusions Mass distribution of LLINs and 6 rounds of IRS dramatically decreased vector density and sporozoite rate resulting in a marked reduction in malaria transmission intensity in a historically high transmission site in Uganda. These changes were accompanied by a shift in vector species from An. gambiae s.s. to An. arabiensis and a relative increase in outdoor biting.

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Patterns of inflammatory responses and parasite tolerance vary with malaria transmission intensity

Malaria Journal ◽

10.1186/s12936-017-1796-x ◽

2017 ◽

Vol 16 (1) ◽

Cited By ~ 14

Author(s):

Temitope W. Ademolue ◽

Yaw Aniweh ◽

Kwadwo A. Kusi ◽

Gordon A. Awandare

Keyword(s):

Malaria Transmission ◽

Inflammatory Responses ◽

Transmission Intensity ◽

Malaria Transmission Intensity

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

Journal of Medical Entomology ◽

10.1093/jmedent/47.4.618 ◽

2010 ◽

Vol 47 (4) ◽

pp. 618-624 ◽

Cited By ~ 6

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.

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Estimating malaria transmission intensity from Plasmodium falciparum serological data using antibody density models

Malaria Journal ◽

10.1186/s12936-016-1121-0 ◽

2016 ◽

Vol 15 (1) ◽

Cited By ~ 22

Author(s):

Emilie Pothin ◽

Neil M. Ferguson ◽

Chris J. Drakeley ◽

Azra C. Ghani

Keyword(s):

Plasmodium Falciparum ◽

Malaria Transmission ◽

Transmission Intensity ◽

Malaria Transmission Intensity ◽

Serological Data

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Mapping malaria transmission intensity using geographical information systems (GIS): an example from Kenya

Annals of Tropical Medicine and Parasitology ◽

10.1080/00034983.1998.11813256 ◽

1998 ◽

Vol 92 (1) ◽

pp. 7-21 ◽

Cited By ~ 13

Author(s):

J. Omumbo ◽

J. Ouma ◽

B. Rapuoda ◽

M. H. Craig ◽

D. Le Sueur ◽

...

Keyword(s):

Information Systems ◽

Malaria Transmission ◽

Geographical Information Systems ◽

Transmission Intensity ◽

Geographical Information ◽

Malaria Transmission Intensity

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

Wellcome Open Research ◽

10.12688/wellcomeopenres.15919.1 ◽

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.

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

10.21203/rs.3.rs-45487/v2 ◽

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.

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