The impact of community-wide, mass drug administration on aggregation of soil-transmitted helminth infection in human host populations
Abstract Background Soil-transmitted helminths (STH) are intestinal parasites estimated to infect over 1.5 billion people. Current treatment programmes are aimed at morbidity control through school-based deworming programmes (targeting school-aged children, SAC) and treating women of reproductive ag...
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| Format: | Article |
| Language: | English |
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BMC
2020-06-01
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| Series: | Parasites & Vectors |
| Subjects: | |
| Online Access: | http://link.springer.com/article/10.1186/s13071-020-04149-4 |
| _version_ | 1818610815101566976 |
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| author | Marleen Werkman James E. Wright James E. Truscott William E. Oswald Katherine E. Halliday Marina Papaiakovou Sam H. Farrell Rachel L. Pullan Roy M. Anderson |
| author_facet | Marleen Werkman James E. Wright James E. Truscott William E. Oswald Katherine E. Halliday Marina Papaiakovou Sam H. Farrell Rachel L. Pullan Roy M. Anderson |
| author_sort | Marleen Werkman |
| collection | DOAJ |
| description | Abstract Background Soil-transmitted helminths (STH) are intestinal parasites estimated to infect over 1.5 billion people. Current treatment programmes are aimed at morbidity control through school-based deworming programmes (targeting school-aged children, SAC) and treating women of reproductive age (WRA), as these two groups are believed to record the highest morbidity. More recently, however, the potential for interrupting transmission by treating entire communities has been receiving greater emphasis and the feasibility of such programmes are now under investigation in randomised clinical trials through the Bill & Melinda Gates Foundation funded DeWorm3 studies. Helminth parasites are known to be highly aggregated within human populations, with a small minority of individuals harbouring most worms. Empirical evidence from the TUMIKIA project in Kenya suggests that aggregation may increase significantly after anthelminthic treatment. Methods A stochastic, age-structured, individual-based simulation model of parasite transmission is employed to better understand the factors that might induce this pattern. A simple probabilistic model based on compounded negative binomial distributions caused by age-dependencies in both treatment coverage and exposure to infection is also employed to further this understanding. Results Both approaches confirm helminth aggregation is likely to increase post-mass drug administration as measured by a decrease in the value of the negative binomial aggregation parameter, k. Simple analytical models of distribution compounding describe the observed patterns well. Conclusions The helminth aggregation that was observed in the field was replicated with our stochastic individual-based model. Further work is required to generalise the probabilistic model to take account of the respective sensitivities of different diagnostics on the presence or absence of infection. |
| first_indexed | 2024-12-16T15:20:25Z |
| format | Article |
| id | doaj.art-63c509a75fc5439cae744d220808f526 |
| institution | Directory Open Access Journal |
| issn | 1756-3305 |
| language | English |
| last_indexed | 2024-12-16T15:20:25Z |
| publishDate | 2020-06-01 |
| publisher | BMC |
| record_format | Article |
| series | Parasites & Vectors |
| spelling | doaj.art-63c509a75fc5439cae744d220808f5262022-12-21T22:26:40ZengBMCParasites & Vectors1756-33052020-06-0113111210.1186/s13071-020-04149-4The impact of community-wide, mass drug administration on aggregation of soil-transmitted helminth infection in human host populationsMarleen Werkman0James E. Wright1James E. Truscott2William E. Oswald3Katherine E. Halliday4Marina Papaiakovou5Sam H. Farrell6Rachel L. Pullan7Roy M. Anderson8London Centre for Neglected Tropical Disease Research (LCNTDR), Department of Infectious Disease Epidemiology, St. Mary’s Campus, Imperial College LondonLondon Centre for Neglected Tropical Disease Research (LCNTDR), Department of Infectious Disease Epidemiology, St. Mary’s Campus, Imperial College LondonLondon Centre for Neglected Tropical Disease Research (LCNTDR), Department of Infectious Disease Epidemiology, St. Mary’s Campus, Imperial College LondonFaculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical MedicineFaculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical MedicineLondon Centre for Neglected Tropical Disease Research (LCNTDR), Department of Infectious Disease Epidemiology, St. Mary’s Campus, Imperial College LondonLondon Centre for Neglected Tropical Disease Research (LCNTDR), Department of Infectious Disease Epidemiology, St. Mary’s Campus, Imperial College LondonFaculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical MedicineLondon Centre for Neglected Tropical Disease Research (LCNTDR), Department of Infectious Disease Epidemiology, St. Mary’s Campus, Imperial College LondonAbstract Background Soil-transmitted helminths (STH) are intestinal parasites estimated to infect over 1.5 billion people. Current treatment programmes are aimed at morbidity control through school-based deworming programmes (targeting school-aged children, SAC) and treating women of reproductive age (WRA), as these two groups are believed to record the highest morbidity. More recently, however, the potential for interrupting transmission by treating entire communities has been receiving greater emphasis and the feasibility of such programmes are now under investigation in randomised clinical trials through the Bill & Melinda Gates Foundation funded DeWorm3 studies. Helminth parasites are known to be highly aggregated within human populations, with a small minority of individuals harbouring most worms. Empirical evidence from the TUMIKIA project in Kenya suggests that aggregation may increase significantly after anthelminthic treatment. Methods A stochastic, age-structured, individual-based simulation model of parasite transmission is employed to better understand the factors that might induce this pattern. A simple probabilistic model based on compounded negative binomial distributions caused by age-dependencies in both treatment coverage and exposure to infection is also employed to further this understanding. Results Both approaches confirm helminth aggregation is likely to increase post-mass drug administration as measured by a decrease in the value of the negative binomial aggregation parameter, k. Simple analytical models of distribution compounding describe the observed patterns well. Conclusions The helminth aggregation that was observed in the field was replicated with our stochastic individual-based model. Further work is required to generalise the probabilistic model to take account of the respective sensitivities of different diagnostics on the presence or absence of infection.http://link.springer.com/article/10.1186/s13071-020-04149-4Soil-transmitted helminthsAggregationStochastic simulations |
| spellingShingle | Marleen Werkman James E. Wright James E. Truscott William E. Oswald Katherine E. Halliday Marina Papaiakovou Sam H. Farrell Rachel L. Pullan Roy M. Anderson The impact of community-wide, mass drug administration on aggregation of soil-transmitted helminth infection in human host populations Parasites & Vectors Soil-transmitted helminths Aggregation Stochastic simulations |
| title | The impact of community-wide, mass drug administration on aggregation of soil-transmitted helminth infection in human host populations |
| title_full | The impact of community-wide, mass drug administration on aggregation of soil-transmitted helminth infection in human host populations |
| title_fullStr | The impact of community-wide, mass drug administration on aggregation of soil-transmitted helminth infection in human host populations |
| title_full_unstemmed | The impact of community-wide, mass drug administration on aggregation of soil-transmitted helminth infection in human host populations |
| title_short | The impact of community-wide, mass drug administration on aggregation of soil-transmitted helminth infection in human host populations |
| title_sort | impact of community wide mass drug administration on aggregation of soil transmitted helminth infection in human host populations |
| topic | Soil-transmitted helminths Aggregation Stochastic simulations |
| url | http://link.springer.com/article/10.1186/s13071-020-04149-4 |
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