The effect of assortative mixing on stability of low helminth transmission levels and on the impact of mass drug administration: Model explorations for onchocerciasis.
BACKGROUND:Stable low pre-control prevalences of helminth infection are not uncommon in field settings, yet it is poorly understood how such low levels can be sustained, thereby challenging efforts to model them. Disentangling possible facilitating mechanisms is important, since these may differentl...
Published in: | PLOS Neglected Tropical Diseases |
---|---|
Main Authors: | , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Public Library of Science (PLoS)
2018
|
Subjects: | |
Online Access: | https://doi.org/10.1371/journal.pntd.0006624 https://doaj.org/article/1372d5ad6f62493a88f11afc02dc5b2d |
id |
ftdoajarticles:oai:doaj.org/article:1372d5ad6f62493a88f11afc02dc5b2d |
---|---|
record_format |
openpolar |
spelling |
ftdoajarticles:oai:doaj.org/article:1372d5ad6f62493a88f11afc02dc5b2d 2023-05-15T15:14:33+02:00 The effect of assortative mixing on stability of low helminth transmission levels and on the impact of mass drug administration: Model explorations for onchocerciasis. Anneke S de Vos Wilma A Stolk Sake J de Vlas Luc E Coffeng 2018-10-01T00:00:00Z https://doi.org/10.1371/journal.pntd.0006624 https://doaj.org/article/1372d5ad6f62493a88f11afc02dc5b2d EN eng Public Library of Science (PLoS) http://europepmc.org/articles/PMC6175282?pdf=render https://doaj.org/toc/1935-2727 https://doaj.org/toc/1935-2735 1935-2727 1935-2735 doi:10.1371/journal.pntd.0006624 https://doaj.org/article/1372d5ad6f62493a88f11afc02dc5b2d PLoS Neglected Tropical Diseases, Vol 12, Iss 10, p e0006624 (2018) Arctic medicine. Tropical medicine RC955-962 Public aspects of medicine RA1-1270 article 2018 ftdoajarticles https://doi.org/10.1371/journal.pntd.0006624 2022-12-31T00:27:40Z BACKGROUND:Stable low pre-control prevalences of helminth infection are not uncommon in field settings, yet it is poorly understood how such low levels can be sustained, thereby challenging efforts to model them. Disentangling possible facilitating mechanisms is important, since these may differently affect intervention impact. Here we explore the role of assortative (i.e. non-homogenous) mixing and exposure heterogeneity in helminth transmission, using onchocerciasis as an example. METHODOLOGY/PRINCIPAL FINDINGS:We extended the established individual-based model ONCHOSIM to allow for assortative mixing, assuming that individuals who are relatively more exposed to fly bites are more connected to each other than other individuals in the population as a result of differential exposure to a sub-population of blackflies. We used the model to investigate how transmission stability, equilibrium microfilarial (mf) prevalence and intensity, and impact of mass drug administration depend on the assumed degree of assortative mixing and exposure heterogeneity, for a typical rural population of about 400 individuals. The model clearly demonstrated that with homogeneous mixing and moderate levels of exposure heterogeneity, onchocerciasis could not be sustained below 35% mf prevalence. In contrast, assortative mixing stabilised onchocerciasis prevalence at levels as low as 8% mf prevalence. Increasing levels of assortative mixing significantly reduced the probability of interrupting transmission, given the same duration and coverage of mass drug administration. CONCLUSIONS/SIGNIFICANCE:Assortative mixing patterns are an important factor to explain stable low prevalence situations and are highly relevant for prospects of elimination. Their effect on the pre-control distribution of mf intensities in human populations is only detectable in settings with mf prevalences <30%, where high skin mf density in mf-positive people may be an indication of assortative mixing. Local spatial variation in larval infection intensity in the ... Article in Journal/Newspaper Arctic Directory of Open Access Journals: DOAJ Articles Arctic PLOS Neglected Tropical Diseases 12 10 e0006624 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Arctic medicine. Tropical medicine RC955-962 Public aspects of medicine RA1-1270 |
spellingShingle |
Arctic medicine. Tropical medicine RC955-962 Public aspects of medicine RA1-1270 Anneke S de Vos Wilma A Stolk Sake J de Vlas Luc E Coffeng The effect of assortative mixing on stability of low helminth transmission levels and on the impact of mass drug administration: Model explorations for onchocerciasis. |
topic_facet |
Arctic medicine. Tropical medicine RC955-962 Public aspects of medicine RA1-1270 |
description |
BACKGROUND:Stable low pre-control prevalences of helminth infection are not uncommon in field settings, yet it is poorly understood how such low levels can be sustained, thereby challenging efforts to model them. Disentangling possible facilitating mechanisms is important, since these may differently affect intervention impact. Here we explore the role of assortative (i.e. non-homogenous) mixing and exposure heterogeneity in helminth transmission, using onchocerciasis as an example. METHODOLOGY/PRINCIPAL FINDINGS:We extended the established individual-based model ONCHOSIM to allow for assortative mixing, assuming that individuals who are relatively more exposed to fly bites are more connected to each other than other individuals in the population as a result of differential exposure to a sub-population of blackflies. We used the model to investigate how transmission stability, equilibrium microfilarial (mf) prevalence and intensity, and impact of mass drug administration depend on the assumed degree of assortative mixing and exposure heterogeneity, for a typical rural population of about 400 individuals. The model clearly demonstrated that with homogeneous mixing and moderate levels of exposure heterogeneity, onchocerciasis could not be sustained below 35% mf prevalence. In contrast, assortative mixing stabilised onchocerciasis prevalence at levels as low as 8% mf prevalence. Increasing levels of assortative mixing significantly reduced the probability of interrupting transmission, given the same duration and coverage of mass drug administration. CONCLUSIONS/SIGNIFICANCE:Assortative mixing patterns are an important factor to explain stable low prevalence situations and are highly relevant for prospects of elimination. Their effect on the pre-control distribution of mf intensities in human populations is only detectable in settings with mf prevalences <30%, where high skin mf density in mf-positive people may be an indication of assortative mixing. Local spatial variation in larval infection intensity in the ... |
format |
Article in Journal/Newspaper |
author |
Anneke S de Vos Wilma A Stolk Sake J de Vlas Luc E Coffeng |
author_facet |
Anneke S de Vos Wilma A Stolk Sake J de Vlas Luc E Coffeng |
author_sort |
Anneke S de Vos |
title |
The effect of assortative mixing on stability of low helminth transmission levels and on the impact of mass drug administration: Model explorations for onchocerciasis. |
title_short |
The effect of assortative mixing on stability of low helminth transmission levels and on the impact of mass drug administration: Model explorations for onchocerciasis. |
title_full |
The effect of assortative mixing on stability of low helminth transmission levels and on the impact of mass drug administration: Model explorations for onchocerciasis. |
title_fullStr |
The effect of assortative mixing on stability of low helminth transmission levels and on the impact of mass drug administration: Model explorations for onchocerciasis. |
title_full_unstemmed |
The effect of assortative mixing on stability of low helminth transmission levels and on the impact of mass drug administration: Model explorations for onchocerciasis. |
title_sort |
effect of assortative mixing on stability of low helminth transmission levels and on the impact of mass drug administration: model explorations for onchocerciasis. |
publisher |
Public Library of Science (PLoS) |
publishDate |
2018 |
url |
https://doi.org/10.1371/journal.pntd.0006624 https://doaj.org/article/1372d5ad6f62493a88f11afc02dc5b2d |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic |
genre_facet |
Arctic |
op_source |
PLoS Neglected Tropical Diseases, Vol 12, Iss 10, p e0006624 (2018) |
op_relation |
http://europepmc.org/articles/PMC6175282?pdf=render https://doaj.org/toc/1935-2727 https://doaj.org/toc/1935-2735 1935-2727 1935-2735 doi:10.1371/journal.pntd.0006624 https://doaj.org/article/1372d5ad6f62493a88f11afc02dc5b2d |
op_doi |
https://doi.org/10.1371/journal.pntd.0006624 |
container_title |
PLOS Neglected Tropical Diseases |
container_volume |
12 |
container_issue |
10 |
container_start_page |
e0006624 |
_version_ |
1766344995364667392 |