Once Bitten: Fighting Dengue Fever in Key West and San Juan

Like many places of mixed or contested governance, parts of San Juan, Puerto Rico, abound in a superfluity of uniforms and titles. It is as though a critical mass of matching cloth and business cards could swaddle a territory into fixed status. On a muggy afternoon in October 2015 at La Ceiba, a panadería just north of the Río Piedras Medical Center and the VA Caribbean veterans’ hospital, east of the US Army’s Fort Buchanan and west of the leafy university district, diners wearing white coats, scrubs, fatigue pants, and the oversized blazers that seem to be pan-American for “teacher” all mingled under frigid air-conditioning vents. Counter attendants served lard- and cheese-centric fritters, sandwiches, and pastries with hot soup, coffee, and wine as I waited for Lieutenant Commander Tyler Sharp.

Sharp first became an officer of the Center for Disease Control and Prevention (CDC) through its Epidemiology Intelligence Service, a cadre of “disease detectives” created in 1951 to combat the threat of bioweapons in the Korean War. He is now a commissioned CDC officer through the US Public Health Service Commissioned Corps, a service established by Congress in 1889 to fight the recurring epidemics of cholera, yellow fever, and other infectious diseases that ravaged the country before modern sanitation and medicine. The interests of the US Public Health Service have generally aligned with those of the enfranchised American public, and that’s often been a good thing: The Public Health Service helped prove that smoking was tied to early mortality, that the organ-failure syndrome known as pellagra came from niacin deficiency, and that AIDS came from HIV. Those same interests of the enfranchised have sometimes been morally and physically catastrophic for more vulnerable populations, such as the black sharecroppers who participated in the Public Health Service’s Tuskegee syphilis experiment, which from 1932 to 1972 observed the ravages of end-stage syphilis long after a penicillin cure was widely and cheaply available. Though the days of such outright abuses are thankfully gone, Puerto Rico’s liminal status with regard to the American mainland leaves it exposed to the possibility of neglect, fickle funding, and the bureaucratic tangles that arise when a semiautonomous but nonsovereign commonwealth tries to work with the federal government and its manifold agencies.

Sharp grew up in Ohio and did the bulk of his undergraduate and graduate studies in Ontario and Texas, focusing on the molecular mechanisms behind viral infections before he realized he wanted to be a step closer to

health care’s front lines. He’s lived in San Juan for nearly six years and speaks English with the slightly lead-footed r’s and toasted vowels of a native Spanish speaker. He likes to quote John F. Kennedy’s 1962 State of the Union address—“The time to repair the roof is when the sun is shining”—when explaining the vigilance that befits a public health officer, however reassuring the island’s tally of official case reports in a given week. He’s in a delicate position, since he and his fellow “feds” assist and collaborate with the Puerto Rico Department of Health at the pleasure of the island’s Secretary of Health, who extends formal written invitations for each CDC endeavor. As administrations and priorities change on the island, CDC officers do their best to defer and keep pace.

Sharp’s nemesis, perhaps public enemy number one of the CDC in Puerto Rico, is the Aedes aegypti mosquito. Aedes aegypti is a domestic animal as beautiful as the housecat—petite among mosquitoes, with dappled legs and a distinctive white “lyre” on its back—and as hardy and reviled as the cockroach. Its peculiar hungers and habits contribute to its frightening success in carrying dengue, chikungunya, West Nile virus, and Zika virus from one human to the next: Unlike other mosquitoes, it eats by day and on the run, able to keep up with a moving ankle and take multiple bites as it goes...