Ignite Creation Date:
2024-05-05 @ 9:19 PM
Last Modification Date:
2024-10-26 @ 10:02 AM
Study NCT ID:
NCT00863408
Status:
COMPLETED
Last Update Posted:
2017-07-02
First Post:
2009-03-17
Brief Title:
Estivation of Malaria Vector Mosquitoes in the Sahelian Region of Mali
Sponsor:
National Institute of Allergy and Infectious Diseases NIAID
Organization:
National Institutes of Health Clinical Center CC
Study Overview
Official Title:
Estivation of Malaria Vector Mosquitoes in the Sahelian Region of Mali Village of Thierola in the District of Banamba
Status:
COMPLETED
Status Verified Date:
2010-03-10
Last Known Status:
None
Delayed Posting:
No
If Stopped, Why?:
Not Stopped
Has Expanded Access:
False
If Expanded Access, NCT#:
N/A
Has Expanded Access, NCT# Status:
N/A
Acronym:
None
Brief Summary:
Background
P falciparum one of the most virulent forms of malaria causes more than 300 million episodes of malaria and 1 million deaths each year The spread of drug-resistant parasites insecticide-resistant mosquitoes and persistent socioeconomic conditions of poverty compound the difficulties of malaria as a major global health problem New means of disease and vector control are vitally needed
Several promising strategies rely on targeting mosquito populations when they are most vulnerable such as during the dry season when mosquitoes find it difficult to reproduce Large regions of the West African country of Mali have prolonged dry seasons up to 8 months during which mosquito populations dramatically decline within a month after the rainfall ceases Clearly mosquitoes can survive the dry season as evident from their robust numbers during the wet season but the process that enables them to do so remains unknown Targeting the small and fragile mosquito population at the end of the dry season could reduce or eliminate the numbers of mosquitoes in certain regions providing great benefits for communities in dry regions
Objectives
To determine if common malaria-carrying mosquitoes survive the dry season in the Mali village of Thierola by estivation going dormant or hibernating during dry periods
To identify and examine mosquitoes that were marked with special paint during a previous protocol if these marked mosquitoes are captured during the investigation
Eligibility
All activities in this protocol will take place in Thierola village Banamba district Koulikoro region Mall West Africa The village was chosen because it is isolated from other communities by at least 6 km and is a small community of less than 300 inhabitants living in 90 houses
Participants will be healthy adult men between 18 and 65 years of age
Design
Thirty adult men who live in Thierola will be recruited to participate as mosquito collectors for the human-baited trapping method and will work in teams of two
The first collector will expose his lower legs to attract human-seeking mosquitoes Using a mouth aspirator the second collector will collect the mosquitoes as they land on the first collectors legs
The collections will be conducted both indoors and outdoors from 6 pm to 6 am the following morning for 14 consecutive days
All study volunteers will be trained in proper collection technique and supervised throughout the study by a mobile team led by the study investigators Volunteers will be monitored for signs of malaria and treated accordingly if they develop symptoms of the disease
Researchers will collect mosquito samples at the end of the dry season April-May and at the start of the rainy season May-June
Mosquitoes collected in the study will be analyzed by NIH researchers to learn more about how they survive during the dry season
P falciparum one of the most virulent forms of malaria causes more than 300 million episodes of malaria and 1 million deaths each year The spread of drug-resistant parasites insecticide-resistant mosquitoes and persistent socioeconomic conditions of poverty compound the difficulties of malaria as a major global health problem New means of disease and vector control are vitally needed
Several promising strategies rely on targeting mosquito populations when they are most vulnerable such as during the dry season when mosquitoes find it difficult to reproduce Large regions of the West African country of Mali have prolonged dry seasons up to 8 months during which mosquito populations dramatically decline within a month after the rainfall ceases Clearly mosquitoes can survive the dry season as evident from their robust numbers during the wet season but the process that enables them to do so remains unknown Targeting the small and fragile mosquito population at the end of the dry season could reduce or eliminate the numbers of mosquitoes in certain regions providing great benefits for communities in dry regions
Objectives
To determine if common malaria-carrying mosquitoes survive the dry season in the Mali village of Thierola by estivation going dormant or hibernating during dry periods
To identify and examine mosquitoes that were marked with special paint during a previous protocol if these marked mosquitoes are captured during the investigation
Eligibility
All activities in this protocol will take place in Thierola village Banamba district Koulikoro region Mall West Africa The village was chosen because it is isolated from other communities by at least 6 km and is a small community of less than 300 inhabitants living in 90 houses
Participants will be healthy adult men between 18 and 65 years of age
Design
Thirty adult men who live in Thierola will be recruited to participate as mosquito collectors for the human-baited trapping method and will work in teams of two
The first collector will expose his lower legs to attract human-seeking mosquitoes Using a mouth aspirator the second collector will collect the mosquitoes as they land on the first collectors legs
The collections will be conducted both indoors and outdoors from 6 pm to 6 am the following morning for 14 consecutive days
All study volunteers will be trained in proper collection technique and supervised throughout the study by a mobile team led by the study investigators Volunteers will be monitored for signs of malaria and treated accordingly if they develop symptoms of the disease
Researchers will collect mosquito samples at the end of the dry season April-May and at the start of the rainy season May-June
Mosquitoes collected in the study will be analyzed by NIH researchers to learn more about how they survive during the dry season
Detailed Description:
Malaria causes over one million deaths annually A promising control strategy relies on targeting mosquito populations when they are vulnerable such as during the dry season Prolonged dry season during which larval sites are scarce and mosquito populations decline prevail in the Sahel which covers a large part of Mali How mosquitoes withstand the dry season remains unknown Some evidence supports the adult estivation hypothesis whereby mosquitoes remain in protected sites except for sporadic journeys to obtain blood-meals to sustain themselves rather than to produce eggs Alternatively mosquitoes do not survive the dry season locally rather they migrate from areas where reproduction continues at permanent water bodies We aim to determine if An Gambiae estivate during the dry season in the Sahel and if so identify their hidden resting sites As mosquito populations decline standard sampling techniques yield zero mosquitoes Because estivating females take blood meals intermittently the most promising sampling technique is by human landing catch HLC Finding a few mosquitoes during the dry season have been reported but it could not be determined if they were estivating or were migrants from villages where larval sites persist This study can resolve this because we captured marked and released over 5000 mosquitoes just before the dry season November 2008 We aim to collect mosquitoes during the end of the dry season April 2009 and the onset of the rainy season June 2009 and find out if they bear marks from the previous wet season Finding a single marked specimen will be the ultimate proof for the estivation hypothesis Experiments will take place in the Sahelian village Thierola Koulikoro Region Mali where the dry season exceeds 7 months The village was chosen because it has no permanent larval sites and is a small community 300 inhabitants living in 90 houses allowing collection in all houses in a single day Thirty adult male residing in Thierola will be recruited as collectors for the HLC A collector will expose his lower legs to attract mosquitoes Using a mouth aspirator mosquitoes will be collected as they land on the collectors legs ideally before a blood meal is taken Collection will be conducted 6pm to 6am for 14 consecutive days in April 2009 and again after the rains begin in June 2009 Collectors will be informed of the proper collecting procedures during the consenting procedure During the time of year we propose to conduct this work mosquito populations will be at their minima and any surviving mosquitoes will take blood meals infrequently Therefore the HLCs will be conducted when malaria transmission is extremely low and the risk to volunteers essentially nil In summary knowledge of how mosquitoes survive the dry season would open novel ways for vector and malaria control
Study Oversight
Has Oversight DMC:
None
Is a FDA Regulated Drug?:
None
Is a FDA Regulated Device?:
None
Is an Unapproved Device?:
None
Is a PPSD?:
None
Is a US Export?:
None
Is an FDA AA801 Violation?:
None
Secondary IDs
| Secondary ID | Type | Domain | Link |
|---|---|---|---|
| 09-I-N093 | None | None | None |