Field Evaluation of Plant-based Mosquito Control

September 1, 2016 updated by: London School of Hygiene and Tropical Medicine

Field Evaluation of Malaria Vector Control Using Traditional Plant-based Anti-mosquito Measures in Yunnan Province, P.R. China

Isolated minority communities in China use traditional plant-based methods of mosquito control. This study is evaluating 4 plants used in this way by monitoring mosquitoes entering houses on nights when the plants are being used in this way. A blind, placebo controlled study design will monitor plant use and record mosquito species / numbers caught in CDC light traps indoors over 3 months.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Introduction

One of the greatest challenges to those planning vector control programmes in developing Countries is the provision of cover to those populations in remote or isolated areas. Commonly, it is these communities which bear the greatest burden of disease due to location and inaccessibility to local health care. Yunnan Province is a good example of such problems. The border region with Laos, Myanmar and Vietnam contributes a high proportion of all malaria cases in the whole of China, yet few if any disease control initiatives cover the rural minority peoples and migrant workers who inhabit the region. Comprehensive ethnobotanical surveys in the area have shown many of the 25 minority peoples living in isolated communities already use traditional herbal forms of mosquito control utilising several of the abundant species in the particularly diverse local environment. Having identified a number of potentially useful plant species being used, in terms of their availability, sustainability, low cost (free) and known chemical constituents, the investigators and the local Chinese malaria control officials consider a phase II evaluation of the most promising candidates is justified. In particular, 4 widely used plants are traditionally used as fumigants to reduce / prevent mosquitoes entering houses, either by burning dried or fresh material on the indoor cooking fires each evening, or by spraying tinctures around entry sites like eaves & windows. Due to the method of use, it would be very difficult to simulate this in the laboratory, so a simple means of field evaluation has been chosen.

Materials

The ethnobotanical survey revealed the following plant species as candidates for further study; Artemesia argyi, Eucalyptus robusta, Eupatorium odoratum, Cinnamomum glanduliferum

Each of these plant species occurs naturally in abundance in the region and collection will have no significant environmental impact. Moderate amounts (approx 1 Kg) sufficient for each study will be collected locally in each field site prior to (if used dried) or at the start of each experiment (fresh).

Methods

Plants will be evaluated under natural user conditions in a randomised and controlled manner in villages in Xishuangbanna Region, Yunnan, PR China. Village- based studies of several other mosquito control methods have already been successfully undertaken in this region by the LSHTM and YIPD team. Villages belonging to one of the ethnic groups using each traditional method will be selected according to agreement between local health workers from YIPD and the village elders, availability of plant species, and preliminary survey of vector species collected indoors with CDC traps. A different village will be selected for each plant being evaluated. After collecting background entomological data, 6 houses matched for baseline parameters (such as occupancy level, location, construction & animal proximity) and being evenly spaced among others in the village (to reduce diversion effects) will be enrolled into the study. On any one night, 2 will be allocated treatment (use of plant), 2 will be allocated hay (used for cattle bedding) as a negative control, and 2 will be left unused (to reduce any residual effects). In each case the treatment or control group will be instructed to place pre-prepared batches of plant material (weighed fresh or dry depending upon type) onto their cooking fire in the traditional manner in the early evening. Commercial CDC traps (BioQuip Inc., USA) will be used in / beside the sleeping areas of each house from 1 hour before sunset to early morning. Catches will be identified by local vector experts each day to record species and number. House treatment will be rotated each night using latin square principles to achieve a minimum of 12 replicates of each treatment in every house (36 nights duration, 216 trap/nights), and will take place during the rainy (malaria) season (July - Nov 2005) when both plants and vector levels are highest.

In the case of C. glanduliferum, the plant extract (or hay extract) will be sprayed at a predetermined rate onto eaves & doors / windows in the traditional manner following the same principles. Efficacy will be determined by comparing mosquito species / numbers caught in control & treatment houses using appropriate statistical analysis & ANOVA methodologies.

Study Type

Interventional

Enrollment (Actual)

240

Phase

  • Phase 2

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

6 years and older (Child, Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Existing use of traditional plant-based methods of mosquito control

Exclusion Criteria:

  • Known allergy to plants in use
  • Respiratory illness
  • Infants under 6 years in house

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Prevention
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
Reduction in vector mosquitoes entering houses
Time Frame: per night over 45 nights
per night over 45 nights

Secondary Outcome Measures

Outcome Measure
Time Frame
Reduced human biting by mosquitoes
Time Frame: per night over 45 nights
per night over 45 nights

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

London School of Hygiene and Tropical Medicine

Collaborators

Yunnan Institute

Investigators

  • Principal Investigator: Nigel Hill, PhD, London School of Hygiene and Tropical Medicine

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

July 1, 2005

Study Completion (Actual)

September 1, 2006

Study Registration Dates

First Submitted

June 30, 2005

First Submitted That Met QC Criteria

June 30, 2005

First Posted (Estimate)

July 1, 2005

Study Record Updates

Last Update Posted (Estimate)

September 2, 2016

Last Update Submitted That Met QC Criteria

September 1, 2016

Last Verified

February 1, 2007

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • DIF28

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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