Changes in Rates of Measles Transmission and Force of Infection in Gweru City, Zimbabwe: A Retrospective Study

Tawanda Marufu; Willard Tinago; Seter Siziya

doi:doi:10.11648/j.ejpm.20160402.11

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Changes in Rates of Measles Transmission and Force of Infection in Gweru City, Zimbabwe: A Retrospective Study

Tawanda Marufu, Willard Tinago, Seter Siziya

Published in European Journal of Preventive Medicine (Volume 4, Issue 2)

Received: 4 February 2016 Accepted: 16 February 2016 Published: 2 March 2016

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Abstract

Introduction A study compared rates of measles transmission and force of infection in pre-vaccination era (1967), and at measles vaccine coverage rates of 50-80% (1978-84) and > 90% (1989). Using measles surveillance data cumulative proportions of measles cases by age were determined for the years 1967, 1978-89 (pooled) and 1989. From the cumulative curves estimates of the age dependent rate of infection with measles (force of infection) was determined for the years 1967, 1978-84 and 1989. Results In 1967 and 1978-84 some 75% of all measles cases occurred by age group 36-47 months while in 1989 this occurred by age group 72-83 months thus measles transmission was most rapid in 1967 and least rapid in 1989. Variation of force of infection between years 1967, 1978-84 and 1967 showed that force of infection was not significantly different between the years for age groups 24-35, 36-47 and 48-59 months. Meanwhile, the force of infection varied between the years in the rest of the age groups, with a significant reduction in force of infection over the years for age groups < 11, and 12-23 months; and significant increases in force of infection were observed in the age groups 60-71, 72-83, 84-95, 96-107 and 108-119 months. Conclusion Measles transmission rates in the community were highest in pre-vaccination era and least at vaccination coverage rates of > 90% most likely due to effect of herd immunity. From pre-vaccination era (1967) to vaccine coverage rates of > 90% (1989) there was a shift in force of infection from young age groups < 23 months to older age groups of 60-119 months most likely due to accumulation of susceptibles in these older age groups. Shift in force of infection to older age groups would have been responsible for the shift in age at infection to these older age groups.

Published in	European Journal of Preventive Medicine (Volume 4, Issue 2)
DOI	10.11648/j.ejpm.20160402.11
Page(s)	28-31
Creative Commons	This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited.
Copyright	Copyright © The Author(s), 2016. Published by Science Publishing Group

Keywords

Measles, Transmission Rates, Force of Infection, Gweru City, Zimbabwe

References

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APA Style

Tawanda Marufu, Willard Tinago, Seter Siziya. (2016). Changes in Rates of Measles Transmission and Force of Infection in Gweru City, Zimbabwe: A Retrospective Study. European Journal of Preventive Medicine, 4(2), 28-31. https://doi.org/10.11648/j.ejpm.20160402.11

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ACS Style

Tawanda Marufu; Willard Tinago; Seter Siziya. Changes in Rates of Measles Transmission and Force of Infection in Gweru City, Zimbabwe: A Retrospective Study. Eur. J. Prev. Med. 2016, 4(2), 28-31. doi: 10.11648/j.ejpm.20160402.11

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Tawanda Marufu, Willard Tinago, Seter Siziya. Changes in Rates of Measles Transmission and Force of Infection in Gweru City, Zimbabwe: A Retrospective Study. Eur J Prev Med. 2016;4(2):28-31. doi: 10.11648/j.ejpm.20160402.11

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@article{10.11648/j.ejpm.20160402.11,
  author = {Tawanda Marufu and Willard Tinago and Seter Siziya},
  title = {Changes in Rates of Measles Transmission and Force of Infection in Gweru City, Zimbabwe: A Retrospective Study},
  journal = {European Journal of Preventive Medicine},
  volume = {4},
  number = {2},
  pages = {28-31},
  doi = {10.11648/j.ejpm.20160402.11},
  url = {https://doi.org/10.11648/j.ejpm.20160402.11},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ejpm.20160402.11},
  abstract = {Introduction A study compared rates of measles transmission and force of infection in pre-vaccination era (1967), and at measles vaccine coverage rates of 50-80% (1978-84) and > 90% (1989). Using measles surveillance data cumulative proportions of measles cases by age were determined for the years 1967, 1978-89 (pooled) and 1989. From the cumulative curves estimates of the age dependent rate of infection with measles (force of infection) was determined for the years 1967, 1978-84 and 1989. Results In 1967 and 1978-84 some 75% of all measles cases occurred by age group 36-47 months while in 1989 this occurred by age group 72-83 months thus measles transmission was most rapid in 1967 and least rapid in 1989. Variation of force of infection between years 1967, 1978-84 and 1967 showed that force of infection was not significantly different between the years for age groups 24-35, 36-47 and 48-59 months. Meanwhile, the force of infection varied between the years in the rest of the age groups, with a significant reduction in force of infection over the years for age groups Conclusion Measles transmission rates in the community were highest in pre-vaccination era and least at vaccination coverage rates of > 90% most likely due to effect of herd immunity. From pre-vaccination era (1967) to vaccine coverage rates of > 90% (1989) there was a shift in force of infection from young age groups < 23 months to older age groups of 60-119 months most likely due to accumulation of susceptibles in these older age groups. Shift in force of infection to older age groups would have been responsible for the shift in age at infection to these older age groups.},
 year = {2016}
}

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TY  - JOUR
T1  - Changes in Rates of Measles Transmission and Force of Infection in Gweru City, Zimbabwe: A Retrospective Study
AU  - Tawanda Marufu
AU  - Willard Tinago
AU  - Seter Siziya
Y1  - 2016/03/02
PY  - 2016
N1  - https://doi.org/10.11648/j.ejpm.20160402.11
DO  - 10.11648/j.ejpm.20160402.11
T2  - European Journal of Preventive Medicine
JF  - European Journal of Preventive Medicine
JO  - European Journal of Preventive Medicine
SP  - 28
EP  - 31
PB  - Science Publishing Group
SN  - 2330-8230
UR  - https://doi.org/10.11648/j.ejpm.20160402.11
AB  - Introduction A study compared rates of measles transmission and force of infection in pre-vaccination era (1967), and at measles vaccine coverage rates of 50-80% (1978-84) and > 90% (1989). Using measles surveillance data cumulative proportions of measles cases by age were determined for the years 1967, 1978-89 (pooled) and 1989. From the cumulative curves estimates of the age dependent rate of infection with measles (force of infection) was determined for the years 1967, 1978-84 and 1989. Results In 1967 and 1978-84 some 75% of all measles cases occurred by age group 36-47 months while in 1989 this occurred by age group 72-83 months thus measles transmission was most rapid in 1967 and least rapid in 1989. Variation of force of infection between years 1967, 1978-84 and 1967 showed that force of infection was not significantly different between the years for age groups 24-35, 36-47 and 48-59 months. Meanwhile, the force of infection varied between the years in the rest of the age groups, with a significant reduction in force of infection over the years for age groups Conclusion Measles transmission rates in the community were highest in pre-vaccination era and least at vaccination coverage rates of > 90% most likely due to effect of herd immunity. From pre-vaccination era (1967) to vaccine coverage rates of > 90% (1989) there was a shift in force of infection from young age groups < 23 months to older age groups of 60-119 months most likely due to accumulation of susceptibles in these older age groups. Shift in force of infection to older age groups would have been responsible for the shift in age at infection to these older age groups.
VL  - 4
IS  - 2
ER  -

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Author Information

Tawanda Marufu

Department of Community Medicine, University of Zimbabwe College of Health Sciences, Harare, Zimbabwe
Willard Tinago

Department of Community Medicine, University of Zimbabwe College of Health Sciences, Harare, Zimbabwe
Seter Siziya

Department of Clinical Sciences, Copperbelt University School of Medicine, Ndola, Zambia

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APA Style

Tawanda Marufu, Willard Tinago, Seter Siziya. (2016). Changes in Rates of Measles Transmission and Force of Infection in Gweru City, Zimbabwe: A Retrospective Study. European Journal of Preventive Medicine, 4(2), 28-31. https://doi.org/10.11648/j.ejpm.20160402.11

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ACS Style

Tawanda Marufu; Willard Tinago; Seter Siziya. Changes in Rates of Measles Transmission and Force of Infection in Gweru City, Zimbabwe: A Retrospective Study. Eur. J. Prev. Med. 2016, 4(2), 28-31. doi: 10.11648/j.ejpm.20160402.11

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AMA Style

Tawanda Marufu, Willard Tinago, Seter Siziya. Changes in Rates of Measles Transmission and Force of Infection in Gweru City, Zimbabwe: A Retrospective Study. Eur J Prev Med. 2016;4(2):28-31. doi: 10.11648/j.ejpm.20160402.11

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@article{10.11648/j.ejpm.20160402.11,
  author = {Tawanda Marufu and Willard Tinago and Seter Siziya},
  title = {Changes in Rates of Measles Transmission and Force of Infection in Gweru City, Zimbabwe: A Retrospective Study},
  journal = {European Journal of Preventive Medicine},
  volume = {4},
  number = {2},
  pages = {28-31},
  doi = {10.11648/j.ejpm.20160402.11},
  url = {https://doi.org/10.11648/j.ejpm.20160402.11},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ejpm.20160402.11},
  abstract = {Introduction A study compared rates of measles transmission and force of infection in pre-vaccination era (1967), and at measles vaccine coverage rates of 50-80% (1978-84) and > 90% (1989). Using measles surveillance data cumulative proportions of measles cases by age were determined for the years 1967, 1978-89 (pooled) and 1989. From the cumulative curves estimates of the age dependent rate of infection with measles (force of infection) was determined for the years 1967, 1978-84 and 1989. Results In 1967 and 1978-84 some 75% of all measles cases occurred by age group 36-47 months while in 1989 this occurred by age group 72-83 months thus measles transmission was most rapid in 1967 and least rapid in 1989. Variation of force of infection between years 1967, 1978-84 and 1967 showed that force of infection was not significantly different between the years for age groups 24-35, 36-47 and 48-59 months. Meanwhile, the force of infection varied between the years in the rest of the age groups, with a significant reduction in force of infection over the years for age groups Conclusion Measles transmission rates in the community were highest in pre-vaccination era and least at vaccination coverage rates of > 90% most likely due to effect of herd immunity. From pre-vaccination era (1967) to vaccine coverage rates of > 90% (1989) there was a shift in force of infection from young age groups < 23 months to older age groups of 60-119 months most likely due to accumulation of susceptibles in these older age groups. Shift in force of infection to older age groups would have been responsible for the shift in age at infection to these older age groups.},
 year = {2016}
}

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TY  - JOUR
T1  - Changes in Rates of Measles Transmission and Force of Infection in Gweru City, Zimbabwe: A Retrospective Study
AU  - Tawanda Marufu
AU  - Willard Tinago
AU  - Seter Siziya
Y1  - 2016/03/02
PY  - 2016
N1  - https://doi.org/10.11648/j.ejpm.20160402.11
DO  - 10.11648/j.ejpm.20160402.11
T2  - European Journal of Preventive Medicine
JF  - European Journal of Preventive Medicine
JO  - European Journal of Preventive Medicine
SP  - 28
EP  - 31
PB  - Science Publishing Group
SN  - 2330-8230
UR  - https://doi.org/10.11648/j.ejpm.20160402.11
AB  - Introduction A study compared rates of measles transmission and force of infection in pre-vaccination era (1967), and at measles vaccine coverage rates of 50-80% (1978-84) and > 90% (1989). Using measles surveillance data cumulative proportions of measles cases by age were determined for the years 1967, 1978-89 (pooled) and 1989. From the cumulative curves estimates of the age dependent rate of infection with measles (force of infection) was determined for the years 1967, 1978-84 and 1989. Results In 1967 and 1978-84 some 75% of all measles cases occurred by age group 36-47 months while in 1989 this occurred by age group 72-83 months thus measles transmission was most rapid in 1967 and least rapid in 1989. Variation of force of infection between years 1967, 1978-84 and 1967 showed that force of infection was not significantly different between the years for age groups 24-35, 36-47 and 48-59 months. Meanwhile, the force of infection varied between the years in the rest of the age groups, with a significant reduction in force of infection over the years for age groups Conclusion Measles transmission rates in the community were highest in pre-vaccination era and least at vaccination coverage rates of > 90% most likely due to effect of herd immunity. From pre-vaccination era (1967) to vaccine coverage rates of > 90% (1989) there was a shift in force of infection from young age groups < 23 months to older age groups of 60-119 months most likely due to accumulation of susceptibles in these older age groups. Shift in force of infection to older age groups would have been responsible for the shift in age at infection to these older age groups.
VL  - 4
IS  - 2
ER  -

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