Environmental factors associated with the distribution of Loa loa vectors Chrysops spp. in Central and West Africa: seeing the forest for the trees.
Africa
Chrysops dimidiata
Chrysops silacea
Climate
Ecology
Environment
Loa loa
Loiasis
MaxEnt
Rainforest
Journal
Parasites & vectors
ISSN: 1756-3305
Titre abrégé: Parasit Vectors
Pays: England
ID NLM: 101462774
Informations de publication
Date de publication:
06 Feb 2019
06 Feb 2019
Historique:
received:
06
12
2018
accepted:
29
01
2019
entrez:
8
2
2019
pubmed:
8
2
2019
medline:
20
2
2019
Statut:
epublish
Résumé
Loiasis is caused by the filarial parasite Loa loa, which is widespread through Central and West Africa and largely confined the tropical equatorial rainforests. The tabanid flies Chrysops silacea and Chrysops dimidiata are the main vectors driving transmission. This study aimed to better define the spatial distribution and ecological niche of the two vectors to help define spatial-temporal risk and target appropriate, timely intervention strategies for filariasis control and elimination programmes. Chrysops spp. distributions were determined by collating information from the published literature into a database, detailing the year, country, locality, latitude/longitude and species collected. Environmental factors including climate, elevation and tree canopy characteristics were summarised for each vector from data obtained from satellite modelled data or imagery, which were also used to identify areas with overt landcover changes. The presence of each Chrysops vector was predicted using a maximum entropy species distribution modelling (MaxEnt) method. A total of 313 location-specific data points from 59 published articles were identified across seven loiasis endemic countries. Of these, 186 sites were included in the climate and elevation analysis, and due to overt landcover changes, 83 sites included in tree canopy analysis and MaxEnt model. Overall, C. silacea and C. dimidiata were found to have similar ranges; annual mean temperature (24.6 °C and 24.1 °C, respectively), annual precipitation (1848.6 mm and 1868.8 mm), elevation (368.8 m and 400.6 m), tree canopy cover (61.4% and 66.9%) and tree canopy height (22.4 m and 25.1 m). MaxEnt models found tree canopy coverage was a significant environmental variable for both vectors. The Chrysops spp. database and large-scale environmental analysis provides insights into the spatial and ecological parameters of the L. loa vectors driving transmission. These may be used to further delineate loiasis risk, which will be important for implementing filariasis control and elimination programmes in the equatorial rainforest region of Central and West Africa.
Sections du résumé
BACKGROUND
BACKGROUND
Loiasis is caused by the filarial parasite Loa loa, which is widespread through Central and West Africa and largely confined the tropical equatorial rainforests. The tabanid flies Chrysops silacea and Chrysops dimidiata are the main vectors driving transmission. This study aimed to better define the spatial distribution and ecological niche of the two vectors to help define spatial-temporal risk and target appropriate, timely intervention strategies for filariasis control and elimination programmes.
METHODS
METHODS
Chrysops spp. distributions were determined by collating information from the published literature into a database, detailing the year, country, locality, latitude/longitude and species collected. Environmental factors including climate, elevation and tree canopy characteristics were summarised for each vector from data obtained from satellite modelled data or imagery, which were also used to identify areas with overt landcover changes. The presence of each Chrysops vector was predicted using a maximum entropy species distribution modelling (MaxEnt) method.
RESULTS
RESULTS
A total of 313 location-specific data points from 59 published articles were identified across seven loiasis endemic countries. Of these, 186 sites were included in the climate and elevation analysis, and due to overt landcover changes, 83 sites included in tree canopy analysis and MaxEnt model. Overall, C. silacea and C. dimidiata were found to have similar ranges; annual mean temperature (24.6 °C and 24.1 °C, respectively), annual precipitation (1848.6 mm and 1868.8 mm), elevation (368.8 m and 400.6 m), tree canopy cover (61.4% and 66.9%) and tree canopy height (22.4 m and 25.1 m). MaxEnt models found tree canopy coverage was a significant environmental variable for both vectors.
CONCLUSIONS
CONCLUSIONS
The Chrysops spp. database and large-scale environmental analysis provides insights into the spatial and ecological parameters of the L. loa vectors driving transmission. These may be used to further delineate loiasis risk, which will be important for implementing filariasis control and elimination programmes in the equatorial rainforest region of Central and West Africa.
Identifiants
pubmed: 30728063
doi: 10.1186/s13071-019-3327-9
pii: 10.1186/s13071-019-3327-9
pmc: PMC6366063
doi:
Types de publication
Journal Article
Langues
eng
Sous-ensembles de citation
IM
Pagination
72Subventions
Organisme : Department for International Development, UK Government
ID : Nil
Organisme : Erasmus+
ID : Nil
Références
Lancet. 2000 Sep 23;356(9235):1077-8
pubmed: 11009145
Trop Med Int Health. 2002 Apr;7(4):371-7
pubmed: 11952954
Ann Trop Med Parasitol. 1953 Dec;47(4):335-9
pubmed: 13125263
Ann Trop Med Parasitol. 1953 Dec;47(4):340-3
pubmed: 13125264
Ann Trop Med Parasitol. 1955 Jun;49(2):193-202
pubmed: 13239082
Ann Trop Med Parasitol. 1955 Oct;49(3):260-72
pubmed: 13259439
Ann Trop Med Parasitol. 1955 Dec;49(4):368-75
pubmed: 13283506
Ann Trop Med Parasitol. 1961 Jul;55:211-6
pubmed: 13696449
Trans R Soc Trop Med Hyg. 2003 Mar-Apr;97(2):183-7
pubmed: 14584374
Trans R Soc Trop Med Hyg. 1950 Jul;44(1):11-47
pubmed: 15443039
Ann Trop Med Parasitol. 2006 Dec;100(8):715-31
pubmed: 17227650
Ann Trop Med Parasitol. 2007 Sep;101(6):499-509
pubmed: 17716433
Med Vet Entomol. 1991 Oct;5(4):413-9
pubmed: 1773119
Clin Microbiol Infect. 2011 Jul;17(7):977-85
pubmed: 21722251
PLoS Negl Trop Dis. 2011 Jun;5(6):e1210
pubmed: 21738809
Am J Trop Med Hyg. 1990 Sep;43(3):282-8
pubmed: 2221224
PLoS Negl Trop Dis. 2012;6(6):e1605
pubmed: 22745838
Trans R Soc Trop Med Hyg. 1990 Jan-Feb;84(1):153-5
pubmed: 2345921
Science. 2013 Nov 15;342(6160):850-3
pubmed: 24233722
Ann Trop Med Parasitol. 1951 May;45(1):38-50
pubmed: 24540873
Trends Parasitol. 2014 Apr;30(4):163-9
pubmed: 24636357
Parasit Vectors. 2014 Jul 03;7:307
pubmed: 24992829
Parasit Vectors. 2014 Aug 15;7:363
pubmed: 25128408
Parasit Vectors. 2015 Jun 12;8:322
pubmed: 26063216
Infect Dis Poverty. 2015 Aug 16;4:36
pubmed: 26279835
Sci Rep. 2016 Feb 12;6:20604
pubmed: 26868185
PLoS Negl Trop Dis. 2016 Apr 29;10(4):e0004437
pubmed: 27128795
Lancet Infect Dis. 2017 Jan;17(1):108-116
pubmed: 27777031
Parasit Vectors. 2017 Apr 5;10(1):172
pubmed: 28381279
Environ Res. 2018 Apr;162:203-210
pubmed: 29353124
Int J Environ Res Public Health. 2018 Jan 23;15(2):
pubmed: 29360797
Parasite Epidemiol Control. 2017 Dec 28;3(1):21-35
pubmed: 29774296
Infect Dis Poverty. 2018 Aug 10;7(1):81
pubmed: 30092816
Ann Soc Belges Med Trop Parasitol Mycol. 1970;50(3):359-60
pubmed: 5514573
Lancet. 1997 Jul 5;350(9070):18-22
pubmed: 9217715