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 animal-to-human and human-to-human transmissibility for human monkeypox in the Democratic Republic of Congo, 1981–1984.The layout is analogous to Figure 5, but now the axes distinguish between animal and human transmission of monkeypox. The data shown in panel C is limited to instances where the transmission links could be unambiguously counted.
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ppat-1004452-g006: Comparing animal-to-human and human-to-human transmissibility for human monkeypox in the Democratic Republic of Congo, 1981–1984.The layout is analogous to Figure 5, but now the axes distinguish between animal and human transmission of monkeypox. The data shown in panel C is limited to instances where the transmission links could be unambiguously counted.

Mentions: Since the infection cluster data for monkeypox contains information on how many primary infections are in each cluster, it can be used to infer the amount of animal-to-human transmission that occurs when infected animals make contact with humans. To accomplish this, we assume that the negative binomial offspring distribution that has been shown to be a good description of human-to-human transmission [23] is also an effective model of animal-to-human transmission. We let represent the average number of primary cases caused by an infected animal that has contact with humans. Our results indicate that the for human-to-human transmission is similar to (Figure 6 and Table 5). There is also evidence that animal-to-human transmission is relatively homogeneous (since the for the preferred model). If one takes the MLEs of and for the preferred model at face value, then we estimate that at least one infection occurs 25% of the time that a infected animal has contact with humans.


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

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

Comparing animal-to-human and human-to-human transmissibility for human monkeypox in the Democratic Republic of Congo, 1981–1984.The layout is analogous to Figure 5, but now the axes distinguish between animal and human transmission of monkeypox. The data shown in panel C is 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-g006: Comparing animal-to-human and human-to-human transmissibility for human monkeypox in the Democratic Republic of Congo, 1981–1984.The layout is analogous to Figure 5, but now the axes distinguish between animal and human transmission of monkeypox. The data shown in panel C is limited to instances where the transmission links could be unambiguously counted.
Mentions: Since the infection cluster data for monkeypox contains information on how many primary infections are in each cluster, it can be used to infer the amount of animal-to-human transmission that occurs when infected animals make contact with humans. To accomplish this, we assume that the negative binomial offspring distribution that has been shown to be a good description of human-to-human transmission [23] is also an effective model of animal-to-human transmission. We let represent the average number of primary cases caused by an infected animal that has contact with humans. Our results indicate that the for human-to-human transmission is similar to (Figure 6 and Table 5). There is also evidence that animal-to-human transmission is relatively homogeneous (since the for the preferred model). If one takes the MLEs of and for the preferred model at face value, then we estimate that at least one infection occurs 25% of the time that a infected animal has contact with humans.

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