Limits...
Detecting differential transmissibilities that affect the size of self-limited outbreaks.

Blumberg S, Funk S, Pulliam JR - PLoS Pathog. (2014)

Bottom Line: Our analysis is based on a branching process model that permits statistical comparison of both the strength and heterogeneity of transmission for two distinct types of cases.When applied to chain size data for MERS-CoV transmission before 2014, our method indicates that despite an apparent trend towards improved control, there is not enough statistical evidence to indicate that R eff has declined with time.Human monkeypox, on the other hand, does not show evidence of differential transmission between animals in contact with humans, primary cases, or secondary cases, which assuages the concern that social mixing can amplify transmission by secondary cases.

View Article: PubMed Central - PubMed

Affiliation: Francis I. Proctor Foundation, University of California San Francisco, San Francisco, California, United States of America; Fogarty International Center, National Institutes of Health, Bethesda, Maryland, United States of America.

ABSTRACT
Our ability to respond appropriately to infectious diseases is enhanced by identifying differences in the potential for transmitting infection between individuals. Here, we identify epidemiological traits of self-limited infections (i.e. infections with an effective reproduction number satisfying [0 < R eff < 1) that correlate with transmissibility. Our analysis is based on a branching process model that permits statistical comparison of both the strength and heterogeneity of transmission for two distinct types of cases. Our approach provides insight into a variety of scenarios, including the transmission of Middle East Respiratory Syndrome Coronavirus (MERS-CoV) in the Arabian peninsula, measles in North America, pre-eradication smallpox in Europe, and human monkeypox in the Democratic Republic of the Congo. When applied to chain size data for MERS-CoV transmission before 2014, our method indicates that despite an apparent trend towards improved control, there is not enough statistical evidence to indicate that R eff has declined with time. Meanwhile, chain size data for measles in the United States and Canada reveal statistically significant geographic variation in R eff, suggesting that the timing and coverage of national vaccination programs, as well as contact tracing procedures, may shape the size distribution of observed infection clusters. Infection source data for smallpox suggests that primary cases transmitted more than secondary cases, and provides a quantitative assessment of the effectiveness of control interventions. Human monkeypox, on the other hand, does not show evidence of differential transmission between animals in contact with humans, primary cases, or secondary cases, which assuages the concern that social mixing can amplify transmission by secondary cases. Lastly, we evaluate surveillance requirements for detecting a change in the human-to-human transmission of monkeypox since the cessation of cross-protective smallpox vaccination. Our studies lay the foundation for future investigations regarding how infection source, vaccination status or other putative transmissibility traits may affect self-limited transmission.

No MeSH data available.


Related in: MedlinePlus

Comparing the transmissibility of primary and secondary cases for human monkeypox in the Democratic Republic of Congo, 1981–1984.The layout is analogous to Figure 4, except that the random network model has been added. The dotted line in panel A shows the relationship between  for primary and secondary infections in the random network model profiled on . The red curve shows the 95% confidence interval for inference with the random network model. The data shown in panels B and C are limited to instances where the transmission links could be unambiguously counted.
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ppat-1004452-g005: Comparing the transmissibility of primary and secondary cases for human monkeypox in the Democratic Republic of Congo, 1981–1984.The layout is analogous to Figure 4, except that the random network model has been added. The dotted line in panel A shows the relationship between for primary and secondary infections in the random network model profiled on . The red curve shows the 95% confidence interval for inference with the random network model. The data shown in panels B and C are limited to instances where the transmission links could be unambiguously counted.

Mentions: As part of the monkeypox surveillance efforts, transmission was tabulated according to the number of cases in each generation of spread [43], [49]. These data can be used to ascertain whether there is a statistically significant difference in primary versus secondary transmission (Figure 5 and Table 4). The results indicate a lack of evidence for a difference between the of primary and secondary cases (seen by noting the overlap of contours with the grey line in Figure 5 and because the preferred model in Table 4 has ). The low values for the maximum likelihood estimates of are consistent with previous studies that infer a high degree of transmission heterogeneity in monkeypox transmission [20], [23].


Detecting differential transmissibilities that affect the size of self-limited outbreaks.

Blumberg S, Funk S, Pulliam JR - PLoS Pathog. (2014)

Comparing the transmissibility of primary and secondary cases for human monkeypox in the Democratic Republic of Congo, 1981–1984.The layout is analogous to Figure 4, except that the random network model has been added. The dotted line in panel A shows the relationship between  for primary and secondary infections in the random network model profiled on . The red curve shows the 95% confidence interval for inference with the random network model. The data shown in panels B and C are limited to instances where the transmission links could be unambiguously counted.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4214794&req=5

ppat-1004452-g005: Comparing the transmissibility of primary and secondary cases for human monkeypox in the Democratic Republic of Congo, 1981–1984.The layout is analogous to Figure 4, except that the random network model has been added. The dotted line in panel A shows the relationship between for primary and secondary infections in the random network model profiled on . The red curve shows the 95% confidence interval for inference with the random network model. The data shown in panels B and C are limited to instances where the transmission links could be unambiguously counted.
Mentions: As part of the monkeypox surveillance efforts, transmission was tabulated according to the number of cases in each generation of spread [43], [49]. These data can be used to ascertain whether there is a statistically significant difference in primary versus secondary transmission (Figure 5 and Table 4). The results indicate a lack of evidence for a difference between the of primary and secondary cases (seen by noting the overlap of contours with the grey line in Figure 5 and because the preferred model in Table 4 has ). The low values for the maximum likelihood estimates of are consistent with previous studies that infer a high degree of transmission heterogeneity in monkeypox transmission [20], [23].

Bottom Line: Our analysis is based on a branching process model that permits statistical comparison of both the strength and heterogeneity of transmission for two distinct types of cases.When applied to chain size data for MERS-CoV transmission before 2014, our method indicates that despite an apparent trend towards improved control, there is not enough statistical evidence to indicate that R eff has declined with time.Human monkeypox, on the other hand, does not show evidence of differential transmission between animals in contact with humans, primary cases, or secondary cases, which assuages the concern that social mixing can amplify transmission by secondary cases.

View Article: PubMed Central - PubMed

Affiliation: Francis I. Proctor Foundation, University of California San Francisco, San Francisco, California, United States of America; Fogarty International Center, National Institutes of Health, Bethesda, Maryland, United States of America.

ABSTRACT
Our ability to respond appropriately to infectious diseases is enhanced by identifying differences in the potential for transmitting infection between individuals. Here, we identify epidemiological traits of self-limited infections (i.e. infections with an effective reproduction number satisfying [0 < R eff < 1) that correlate with transmissibility. Our analysis is based on a branching process model that permits statistical comparison of both the strength and heterogeneity of transmission for two distinct types of cases. Our approach provides insight into a variety of scenarios, including the transmission of Middle East Respiratory Syndrome Coronavirus (MERS-CoV) in the Arabian peninsula, measles in North America, pre-eradication smallpox in Europe, and human monkeypox in the Democratic Republic of the Congo. When applied to chain size data for MERS-CoV transmission before 2014, our method indicates that despite an apparent trend towards improved control, there is not enough statistical evidence to indicate that R eff has declined with time. Meanwhile, chain size data for measles in the United States and Canada reveal statistically significant geographic variation in R eff, suggesting that the timing and coverage of national vaccination programs, as well as contact tracing procedures, may shape the size distribution of observed infection clusters. Infection source data for smallpox suggests that primary cases transmitted more than secondary cases, and provides a quantitative assessment of the effectiveness of control interventions. Human monkeypox, on the other hand, does not show evidence of differential transmission between animals in contact with humans, primary cases, or secondary cases, which assuages the concern that social mixing can amplify transmission by secondary cases. Lastly, we evaluate surveillance requirements for detecting a change in the human-to-human transmission of monkeypox since the cessation of cross-protective smallpox vaccination. Our studies lay the foundation for future investigations regarding how infection source, vaccination status or other putative transmissibility traits may affect self-limited transmission.

No MeSH data available.


Related in: MedlinePlus