In eight years of climate change blogging we think we have uniformly been able to steer clear of the prurient and the provocative, the lewd and the lascivious. But then came word last Friday from New York that the New York City Department of Health and Mental Hygiene had confirmed the zika virus – now endemic in Central and South America and the Caribbean and blamed for birth defects including microcephaly -- had been transmitted from a female to her male sexual partner. I checked with my censors. No, I couldn't go there (the CDC does). But not for the reasons you think.
The real climate change story is the habits of mosquitoes (bedroom and otherwise), not of humans. To get that information, of course, one needs to go to the scientific literature. We found Biological and Physical Signs of Climate Change: Focus on Mosquito-borne Diseases by Paul R. Epstein et al. That has plenty.
It is well-documented that mosquitoes “are highly sensitive to climatic factors.” Mosquito ranges are constrained by temperature thresholds. Research puts the ambient temperature ranges at above 16 °C (60 °F) but below 40 °C (104 °F). These apply to both altitude and latitude. Scientists refer to the geographical plotting of these as, for example, the 16 °C isotherm. As temperatures between the boundary isotherms increase mosquito populations also increase, as do “biting rates (blood meals)”, and activity. Outside the boundary isotherms breeding and development fall off rapidly. Note, however, that mosquitoes can overwinter (think hibernate) in colder climes and begin breeding and development when the weather warms..
Further, the incubation periods for the parasites and viruses transmitted by mosquitoes are also temperature dependent. One study found the incubation period for the malaria virus was halved with a 5 °C temperature increase.
All of this suggests that ranges for mosquito-borne diseases should be increasing in a world of increasing temperature. Studies confirm that mosquito-borne diseases are showing up at higher elevations, see Epstein et al., but also are moving toward the poles. In fact, Florida on Tuesday announced that it was “conducting an investigation into a possible non-travel related case of Zika virus in Miami-Dade County." If confirmed, this would be the first documented case of mosquito-borne zika virus in the continental United States.
But how does all this technical detail help a lawyer advise his or her clients? The details provide the context and raise the issues. The lawyer then needs to respond. Mosquito-borne illnesses exacerbated by climate change impact our clients in at least two ways. First, there are the employment issues. How does the expansion of the endemic zone of mosquito-borne illnesses affect our work force? Can we require our employees to travel to such areas? Can we require them to stay out of the workplace during any incubation or contagion period? In light of the dire effects of the zika virus, can we impose requirements on pregnant or intended-pregnant employees?
Second, how does the changing range of mosquito-borne illnesses affect your client’s contractual protection against risk? The lawyer will not be making the decision on whether to open a new hotel in Colombia or Cuba or South Florida. But he or she certainly should be vetting force majeure clauses and insurance programs for protection against the risks associated with these new enterprises. Can the client get out of a contract if zika goes from endemic to epidemic? What disclosures need to be made, or warnings given, to tourists coming to the hotel?
We can’t possibly ask all the questions here, nor will readers find all the answers. Nevertheless, every journey begins with a single step, or in the case of a problem arising from a zika-infected mosquito, a single bite.