A Randomized Controlled Trial of Interventions to Impede Date Palm Sap Contamination by Bats to Prevent Nipah Virus Transmission in Bangladesh
Salah Uddin Khan<SUP>1</SUP><SUP>*</SUP>, Emily S. Gurley<SUP>1</SUP>, M. Jahangir Hossain<SUP>1</SUP>, Nazmun Nahar<SUP>1</SUP>, M. A. Yushuf Sharker<SUP>1</SUP>, Stephen P. Luby<SUP>1</SUP><SUP>,</SUP><SUP>2</SUP>
1 International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B), Dhaka, Bangladesh, 2 Centers for Disease Control and Prevention (CDC), Atlanta, Georgia, United States of America
Abstract
Background
Drinking raw date palm sap is a risk factor for human Nipah virus (NiV) infection. Fruit bats, the natural reservoir of NiV, commonly contaminate raw sap with saliva by licking date palm?s sap producing surface. We evaluated four types of physical barriers that may prevent bats from contacting sap.
Methods
During 2009, we used a crossover design and randomly selected 20 date palm sap producing trees and observed each tree for 2 nights: one night with a bamboo skirt intervention applied and one night without the intervention. During 2010, we selected 120 trees and randomly assigned four types of interventions to 15 trees each: bamboo, dhoincha (local plant), jute stick and polythene skirts covering the shaved part, sap stream, tap and collection pot. We enrolled the remaining 60 trees as controls. We used motion sensor activated infrared cameras to examine bat contact with sap.
Results
During 2009 bats contacted date palm sap in 85% of observation nights when no intervention was used compared with 35% of nights when the intervention was used [p<0.001]. Bats were able to contact the sap when the skirt did not entirely cover the sap producing surface. Therefore, in 2010 we requested the sap harvesters to use larger skirts. During 2010 bats contacted date palm sap [2% vs. 83%, p<0.001] less frequently in trees protected with skirts compared to control trees. No bats contacted sap in trees with bamboo (p<0.001 compared to control), dhoincha skirt (p<0.001) or polythene covering (p<0.001), but bats did contact sap during one night (7%) with the jute stick skirt (p<0.001).
Conclusion
Bamboo, dhoincha, jute stick and polythene skirts covering the sap producing areas of a tree effectively prevented bat-sap contact. Community interventions should promote applying these skirts to prevent occasional Nipah spillovers to human.
Citation: Khan SU, Gurley ES, Hossain MJ, Nahar N, Sharker MAY, et al. (2012) A Randomized Controlled Trial of Interventions to Impede Date Palm Sap Contamination by Bats to Prevent Nipah Virus Transmission in Bangladesh. PLoS ONE 7(8): e42689. doi:10.1371/journal.pone.0042689
Editor: Patrick C. Y. Woo, The University of Hong Kong, China
Received: February 14, 2012; Accepted: July 10, 2012; Published: August 8, 2012
This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.
Funding: This research study was funded by the United States Centers for Disease Control and Prevention (CDC) grant numbers 5U01CI00298-05 and 3U01CI00628-01. ICDDR,B acknowledges with gratitude the commitment of the CDC to it?s research efforts. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the CDC or the ICDDR,B. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
* E-mail: khansu@icddrb.org
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Salah Uddin Khan<SUP>1</SUP><SUP>*</SUP>, Emily S. Gurley<SUP>1</SUP>, M. Jahangir Hossain<SUP>1</SUP>, Nazmun Nahar<SUP>1</SUP>, M. A. Yushuf Sharker<SUP>1</SUP>, Stephen P. Luby<SUP>1</SUP><SUP>,</SUP><SUP>2</SUP>
1 International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B), Dhaka, Bangladesh, 2 Centers for Disease Control and Prevention (CDC), Atlanta, Georgia, United States of America
Abstract
Background
Drinking raw date palm sap is a risk factor for human Nipah virus (NiV) infection. Fruit bats, the natural reservoir of NiV, commonly contaminate raw sap with saliva by licking date palm?s sap producing surface. We evaluated four types of physical barriers that may prevent bats from contacting sap.
Methods
During 2009, we used a crossover design and randomly selected 20 date palm sap producing trees and observed each tree for 2 nights: one night with a bamboo skirt intervention applied and one night without the intervention. During 2010, we selected 120 trees and randomly assigned four types of interventions to 15 trees each: bamboo, dhoincha (local plant), jute stick and polythene skirts covering the shaved part, sap stream, tap and collection pot. We enrolled the remaining 60 trees as controls. We used motion sensor activated infrared cameras to examine bat contact with sap.
Results
During 2009 bats contacted date palm sap in 85% of observation nights when no intervention was used compared with 35% of nights when the intervention was used [p<0.001]. Bats were able to contact the sap when the skirt did not entirely cover the sap producing surface. Therefore, in 2010 we requested the sap harvesters to use larger skirts. During 2010 bats contacted date palm sap [2% vs. 83%, p<0.001] less frequently in trees protected with skirts compared to control trees. No bats contacted sap in trees with bamboo (p<0.001 compared to control), dhoincha skirt (p<0.001) or polythene covering (p<0.001), but bats did contact sap during one night (7%) with the jute stick skirt (p<0.001).
Conclusion
Bamboo, dhoincha, jute stick and polythene skirts covering the sap producing areas of a tree effectively prevented bat-sap contact. Community interventions should promote applying these skirts to prevent occasional Nipah spillovers to human.
Citation: Khan SU, Gurley ES, Hossain MJ, Nahar N, Sharker MAY, et al. (2012) A Randomized Controlled Trial of Interventions to Impede Date Palm Sap Contamination by Bats to Prevent Nipah Virus Transmission in Bangladesh. PLoS ONE 7(8): e42689. doi:10.1371/journal.pone.0042689
Editor: Patrick C. Y. Woo, The University of Hong Kong, China
Received: February 14, 2012; Accepted: July 10, 2012; Published: August 8, 2012
This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.
Funding: This research study was funded by the United States Centers for Disease Control and Prevention (CDC) grant numbers 5U01CI00298-05 and 3U01CI00628-01. ICDDR,B acknowledges with gratitude the commitment of the CDC to it?s research efforts. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the CDC or the ICDDR,B. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
* E-mail: khansu@icddrb.org