Posts

2017-08-22: A rebuttal on the beauty in applying math

2017-04-22: Free googles book library

2016-11-02: In search of Theodore von Karman

2016-09-25: Amath Timeline

2016-02-24: Math errors and risk reporting

2016-02-20: Apple VS FBI

2016-02-19: More Zika may be better than less

2016-02-17: Dependent Non-Commuting Random Variable Systems

2016-01-14: Life at the multifurcation

2015-09-28: AI ain't that smart

2015-06-24: MathEpi citation tree

2015-03-31: Too much STEM is bad

2015-03-24: Dawn of the CRISPR age

2015-02-12: A Comment on How Biased Dispersal can Preclude Competitive Exclusion

2015-02-09: Hamilton's selfish-herd paradox

2015-02-08: Risks and values of microparasite research

2014-11-10: Vaccine mandates and bioethics

2014-10-18: Ebola, travel, president

2014-10-17: Ebola comments

2014-10-12: Ebola numbers

2014-09-23: More stochastic than?

2014-08-17: Feynman's missing method for third-orders?

2014-07-31: CIA spies even on congress

2014-07-16: Rehm on vaccines

2014-06-21: Kurtosis, 4th order diffusion, and wave speed

2014-06-20: Random dispersal speeds invasions

2014-05-06: Preservation of information asymetry in Academia

2014-04-16: Dual numbers are really just calculus infinitessimals

2014-04-14: More on fairer markets

2014-03-18: It's a mad mad mad mad prisoner's dilemma

2014-03-05: Integration techniques: Fourier--Laplace Commutation

2014-02-25: Fiber-bundles for root-polishing in two dimensions

2014-02-17: Is life a simulation or a dream?

2014-01-30: PSU should be infosocialist

2014-01-12: The dark house of math

2014-01-11: Inconsistencies hinder pylab adoption

2013-12-24: Cuvier and the birth of extinction

2013-12-17: Risk Resonance

2013-12-15: The cult of the Levy flight

2013-12-09: 2013 Flu Shots at PSU

2013-12-02: Amazon sucker-punches 60 minutes

2013-11-26: Zombies are REAL, Dr. Tyson!

2013-11-22: Crying wolf over synthetic biology?

2013-11-21: Tilting Drake's Equation

2013-11-18: Why $1^\infty != 1$

2013-11-15: Adobe leaks of PSU data + NSA success accounting

2013-11-14: 60 Minutes misreport on Benghazi

2013-11-11: Making fairer trading markets

2013-11-10: L'Hopital's Rule for Multidimensional Systems

2013-11-09: Using infinitessimals in vector calculus

2013-11-08: Functional Calculus

2013-11-03: Elementary mathematical theory of the health poverty trap

2013-11-02: Proof of the area of a circle using elementary methods

More Zika may be better than less

This winter, the on-going Zika epidemic made big headlines. Zika is a virus transmitted by the Aedes aegypti mosquito. Most Zika infections appear to be asymptomatic or mild, but the possible link of Zika infection in pregnant women to birth defects has lead to allot of publicity. We suddenly find ourselves in a race against time to develop a good vaccine or implement effective control measures before more babies are harmed. A number of countries in South and Central America have responded by discouraging pregnancy -- something that is controversial because of the lack of reproductive rights for women in these nations.

The CDC supplies basic information about Zika. What's interesting is that Zika may be one of the unusual cases where the obvious response is not the best. Our gut reaction when we hear about a new epidemic is to stop it, the sooner the better and by whatever means we can. However, the virulence effects of Zika appear to be heterogeneous and these heterogeneities can have consequences that are the opposite of our natural instincts.

There is a concept in veterinary science called "endemic stablity" -- perhaps it would be better to call it "endemic advantage". In the classic situation, an animal who get's sick while young suffers mild consequences, while an animal that get's sick when old suffers serious morbidity or mortality. Thus, while it's not good to get sick, it's better to get sick sooner than later. As a consequence, its sometimes better to maximize transmission, rather than minimize transmission. This holds whether it's a central planner making a decision or individuals making choices for themselves (1, 2, 3). This same argument also applies rubella, which is generally mild but can cause complications in pregnant women. Women who get rubella while they are young and immune for the rest of their lives are better off than women who might not get rubella until they reach child-bearing age.

Zika may fall into the same category as rubella. Zika's symptoms appear to usually be mild or absent and the evidence suggests that Zika infection induces long-term immunity against re-infection in the future. So maximizing Zika transmission might lead to young women begin immune by the time they reach child-baring age, thus mitigating the worst potential effects. In addition, this would be something that could empower individuals, and not rely on government intervention -- it's a choice everybody can make for themselves.

Of course, there's lots of uncertainty currently about Zika, and new facts are always changing our assessments. If Zika infection persists in the body for an extended period of time after exposure, for example, the benefits of early infection would diminish. And if Zika causes it's own serious morbidity like Guillain-Barre syndrome, postponing infection may in fact be better than advancing it. From a public policy perspective, the demographic pyramic of a nation can have important implications, because of differences in the number of women entering and leaving reproductive ages. Further, since the mosquitoe vector that seems to be responsible for most of the transmission of Zika is also the vector for Dengue fever and Yellow fever, maximizing Zika transmission may have knock-on negative conseequences if implemented poorly.

We have much to learn still, but we should probably keep an open mind about the best control strategies in the short, medium, and long terms.