How Humans Sank New Orleans

Engineering put the Crescent City below sea level. Now, its future is at risk.

A drone photo of downtown New Orleans and the Mississippi River, with the French Quarter in the foreground and the West Bank in the distance

Below sea level. It’s a universally known topographical factoid about the otherwise flat city of New Orleans, and one that got invoked ad nauseam during worldwide media coverage of Hurricane Katrina and its catastrophic aftermath in 2005. Locally, the phrase is intoned with a mix of civic rue and dark humor.

It’s also off by half. Depending on where exactly one frames the area measured, roughly 50 percent of greater New Orleans lies above sea level. That’s the good news. The bad news: It used to be 100 percent, before engineers accidentally sank half the city below the level of the sea. Their intentions were good, and they thought they were solving an old problem. Instead, they created a new and bigger one.

Three hundred years ago this spring, French colonials first began clearing vegetation to establish La Nouvelle-Orléans on the meager natural levee of the Mississippi River. At most 10 to 15 feet above sea level, this feature accounts for nearly all the region’s upraised terrain; the rest is swamp or marsh. One Frenchman called it “Nothing more than two narrow strips of land, about a musket shot in width,” surrounded by “canebrake [and] impenetrable marsh.”

For two centuries after the establishment of New Orleans in 1718, urban expansion had no choice but to exploit this slender ridge—so much so that many patterns of local history, from urbanization and residential settlement geographies to architecture and infrastructure, spatially echoed the underlying topography.

New Orleans and its vicinity in 1863. The developing city tightly hugs the ridge nearest the Mississippi River.
This might seem paradoxical to anyone who’s visited the Crescent City. What topography? In one of the flattest regions on the continent, how can elevation matter so much? But that’s exactly the point: The lower the supply of a highly demanded resource, the more valuable it becomes. Unlike most other cities, which may have elevational ranges in the hundreds of feet, just a yard of vertical distance in New Orleans can make the difference between a neighborhood developed in the Napoleonic Age, the Jazz Age, or the Space Age.

Understanding how these features rose, and why they later sank, entails going back to the end of the Ice Age, when melting glaciers sent sediment-laden runoff down the Mississippi to the Gulf of Mexico. Starting around 7,200 years ago, the river’s mouth began pressing seaward, dumping sediments faster than currents and tides could sweep them away. The mud accumulated, and lower Louisiana gradually emerged from the Gulf shore.

Areas closest to the river and its branches rose the highest in elevation, because they got the most doses of the coarsest sediment. Areas farther from the river got just enough silt and clay particles to rise only slightly above the sea, becoming swamps. Areas farthest out received scanty deposition of the finest particles amid brackish tides, becoming grassy wetlands or saline marsh. The entire delta, under natural conditions, lay above sea level, ranging from a few inches along the coastal fringe to over a dozen feet high at the crest of the Mississippi River’s natural levee. Nature built lower Louisiana above sea level, albeit barely—and mutably.

Native peoples generally adapted to this fluidity, shoring up the land or moving to higher ground as floodwaters rose. But then European imperialists came to colonize. Colonization meant permanency, and permanency meant imposing engineering rigidity on this soft, wet landscape: levees to keep water out, canals to dry soil, and in time, pumps to push and lift water out of canals lined with floodwalls.

All this would take decades to erect and centuries to perfect. In the meantime, throughout the French and Spanish colonial eras, and under American dominion after the Louisiana Purchase in 1803, New Orleanians had no choice but to squeeze their booming metropolis onto those “two narrow strips of land” while eschewing the low-lying “canebrake [and] impenetrable marsh.” Folks hated every inch of that backswamp, viewing it as a source of miasmas, the cause of disease, and a constraint on growth and prosperity. One observer in 1850 unloaded on the wetlands: “This boiling fountain of death is one of the most dismal, low, and horrid places, on which the light of the sun ever shone. And yet there it lies under the influence of a tropical heat, belching up its poison and malaria … the dregs of the seven vials of wrath … covered with a yellow greenish scum.”

Only later people would learn that it was not miasmas but the invasive Aedes aegypti mosquito, brought in by transatlantic shipping, that caused diseases like yellow fever; that it was urban cisterns and poor sanitation that enabled mosquitoes to breed and feed on human blood; and that the “dismal, low” terrain actually aided the city by storing excess water, be it from the sky, the Mississippi River, the bay known as Lake Pontchartrain, or the Gulf of Mexico. It was not “horrid” but propitious that nobody lived in the backswamp, and that the technology to drain it was not available. And most importantly, that the “yellow greenish scum” lay above sea level.

Understandably, given the incompatibility of natural deltaic processes with urbanization, New Orleanians began erecting embankments along the river and digging drainage ditches within a year of the city’s foundation. One colonist described how settlers in 1722 were “ordained [to] leave all around [their city parcel] a strip at least three feet wide, at the foot of which a ditch was to be dug, to serve as a drain.” Outflow canals were excavated to speed drainage back toward the swamp, and in nearby plantations, ditches were dug to control soil water or divert river water to power sawmills.

Gravity was the main source of energy for these initial water projects, but in the early 1800s, steam power came into the picture. In 1835, the New Orleans Drainage Company began digging a network of urban ditches, using a steam-driven pump to push the runoff back out of Bayou St. John—with limited success. A similar pumping system was attempted in the late 1850s, only to be disrupted by the Civil War. In 1871, the Mississippi and Mexican Gulf Ship Canal Company dug 36 miles of ditches, including three major outfall canals, before it too went bankrupt.

It was becoming clear that draining New Orleans would best be stewarded by the public sector instead. Municipal engineers in the late 1800s cobbled together the extant network of gutters and ditches and, with the propulsion of some steam-driven pumps, were able to expel up to one-and-a-half inches of rainfall per day into surrounding water bodies.

That wasn’t nearly enough to drain the swamp, but it was enough to begin permanently altering the New Orleans’s land surface. We know this because in 1893, when the city finally got serious and funded expert engineers to figure out how to solve this problem, surveyors set out to map local elevations as had never been done before. The resulting topographical map of New Orleans (1895) would inform the engineering of what would become a world-class system.

Contour map of New Orleans, produced as part of the city’s 1895 effort to finally solve the drainage problem

The 1895 map also revealed something curious: The rear precincts of one downtown faubourg had, for the first time, dipped slightly below sea level. The sinkage would not bode well for things to come.

What was beginning to happen was anthropogenic soil subsidence—the sinking of the land by human action. When runoff is removed and artificial levees prevent the river from overtopping, the groundwater lowers, the soils dry out, and the organic matter decays. All this creates air pockets in the soil body, into which those sand, silt, and clay particles settle, consolidate—and drop below sea level.

Construction of the new drainage system began in 1896 and accelerated in 1899, when voters overwhelmingly approved a two-mill property tax to create the New Orleans Sewerage and Water Board. By 1905, 40 miles of canal had been excavated, hundreds of miles of pipelines and drains had been laid, and six pumping stations were draining up to 5,000 cubic feet of water per second. System efficacy improved dramatically after 1913, when a young engineer named Albert Baldwin Wood designed an enormous impeller pump that could discharge water even faster. Eleven “Wood screw pumps” were installed by 1915, and many are still in use today. By 1926, over 30,000 acres of land had been “reclaimed” via 560 miles of pipes and canals with a capacity of 13,000 cubic feet of water per second. New Orleans had finally conquered its backswamp.

The change in urban geography was dramatic. Within a decade or so, swampland became suburbs. Property values soared, tax coffers swelled, and urbanization sprawled onto lower ground toward Lake Pontchartrain. “The entire institutional structure of the city” reveled in the victory over nature, wrote John Magill, a local historian. “Developers promoted expansion, newspapers heralded it, the City Planning Commission encouraged it, the city built streetcars to service it, [and] the banks and insurance companies underwrote the financing.” The white middle class, eager to flee crumbling old faubourgs, moved into the new “lakefront” neighborhoods en masse, to the point of excluding black families through racist deed covenants. And in a rebuke of two centuries of local architectural tradition, new tract housing was built not raised on piers above the grade, but on concrete slabs poured at grade level. Why design against floods if technology has already solved that problem?

Design plans for a Wood screw pump (U.S. Patent 1,345,655)

The change in topographic elevation was more subtle, but equally consequential. A city that had been entirely above sea level into the late 1800s, and over 95 percent in 1895, had by 1935 fallen to about 70 percent above sea level.

Subsidence continued even as more and more people moved into subsiding areas. While the vast majority of New Orleans’s 300,000 residents lived above sea level in the early 1900s, only 48 percent remained above the water in 1960, when the city’s population peaked at 627,525. That year, 321,000 residents lived on former swamp, over which time they dropped into a series of topographical bowls four to seven feet below sea level.

The average New Orleanian of this era perceived being below sea level as something of a local curiosity. Then as now, most folks did not understand that this was a recent man-made accident, or that it could become hazardous. But streets increasingly buckled and buildings cracked. When Hurricane Betsy ruptured levees and flooded the bottoms of four sunken urban basins in 1965, the curiosity became more of a crisis.

Soil subsidence made frightful headlines in the 1970s, when at least eight well-maintained houses in a suburban subdivision exploded without warning. “Scores of Metairie residents,” The New Orleans Times-Picayune reported, “wondered whether they are living in what amounts to time bombs.” The affected subdivision, low-lying to begin with and positioned on an especially thick layer of peat, had been drained just over a decade earlier. With so much “wet sponge” to dry out, the soils compacted rapidly and subsided substantially, cracking slab foundations. In some cases, gas lines broke and vapors leaked into the house, after which all it took was a flicked light switch or a lit cigarette to explode.

The emergency was abated through ordinances requiring foundational pilings and flexible utility connections. But the larger problem only worsened, as gardens, streets, and parks continued to subside, and those neighborhoods that abutted surrounding water bodies had to be lined with new lateral levees and floodwalls. Many of those and other federal structures proved to be under-engineered, underfunded, and under-inspected, and all too many failed in the face of Hurricane Katrina’s storm surge on August 29, 2005. The rest is topographic history, as seawater poured through the breaches and filled bowl-shaped neighborhoods with up to 12 feet of saltwater. Large-scale death and catastrophic destruction resulted, in part, from New Orleans having dropped below sea level.

A LIDAR elevation model of New Orleans shows areas above sea level in red tones (up to 10 or 15 feet, except for the artificial levees) and areas below sea level in yellow to blueish tones (mostly ranging from -1 down to -10 feet)

What to do? Urban subsidence cannot be reversed. Engineers and planners cannot “reinflate” compacted soils if city dwellers have built lives upon them. But they can reduce and possibly eliminate future sinkage by slowing the movement of runoff across the cityscape and storing as much water as possible on the surface, thus recharging the groundwater and filling those air cavities. The Greater New Orleans Urban Water Plan, conceived by a local architect, David Waggonner, in dialogues with Dutch and Louisiana colleagues, lays out a vision of how such a system would work. But even if executed fully, the plan would not reverse past subsidence. This means that greater New Orleans and the rest of the nation must be committed to maintaining and improving structural barriers to prevent outside water from pouring into “the bowl.”

To a degree, those resources arrived after Katrina, when the Army Corps of Engineers fast-tracked the design and construction of a unique-in-the-nation Hurricane and Storm Damage Risk-Reduction System. Costing over $14.5 billion and completed in 2011, “The Wall,” as folks call the sprawling complex, aims to keep those living inside secure from flooding from storms computed to have a 1 percent chance of occurring in any given year—not the level of security needed, but an improvement nonetheless.

Yet, history shows that “walls” (that is, levees, embankments, floodwalls, and other rigid barriers) have gotten New Orleans into topographical trouble, even if they have also been essential to the viability of this 300-year-old experiment in delta urbanism. The city cannot rely on them alone. The biggest and most important part of assuring a future for this region is to supplement structural solutions with nonstructural approaches.

Louisiana’s coast has eroded by over 2,000 square miles since the 1930s, mostly on account of the leveeing of the Mississippi River and the excavation of oil, gas, and navigation canals—not to mention rising sea levels and intruding saltwater. Slowing that loss requires tapping into the very feature that built this landscape, the Mississippi River, by diverting its freshwater and siphoning its sediment load onto the coastal plain, pushing back intruding saltwater and shoring up wetlands at a pace faster than the sea is rising.

Restored wetlands would serve to impede hurricane storm surges, reducing their height and power before reaching “The Wall,” and thus lessening the chances that they break through and inundate “the bowl.” A federally backed state plan by the Coastal Protection and Restoration Authority is now complete and approved, and some projects are underway. But the larger effort is a moonshot, costing at least $50 billion and possibly double that. Only a fraction of the needed revenue is in hand.

Meanwhile, inhabitants will have to raise their residences above base-flood elevation (a requirement to qualify for federal flood insurance). If finances allow, they might opt to live in the half of the metropolis that remains above sea level. Collectively, they might consider advocating for the Urban Water Plan, supporting coastal restoration efforts, and understanding the larger global drivers of sea-level rise.

They can also forswear draining any further wetlands for urban development. Let swamps and marshes instead be green with grass, blue with water, absorptive in the face of heavy rainfall, buffering in their effect on storm surges—and above sea level in their topographic elevation. When it comes to living being below sea level, New Orleanians have little choice but to adapt.

New Diagnostic Test for Blood Cancers Will Help doctors.

Pictured: Ross Levine
Physician-scientist Ross Levine

A new diagnostic test that identifies genetic alterations in blood cancers will enable physicians to match patients with the best treatments for leukemias, lymphomas, and myelomas. Co-developed by Memorial Sloan-Kettering and cancer genomics company Foundation Medicine, the test analyzes samples from patients with the blood diseases and provides information about hundreds of genes known to be associated with these disorders.

The genetic profile will help physicians make more-accurate prognoses and also guide them in treatment recommendations — from deciding whether to take an intensive approach with existing drugs such as chemotherapy to enrolling patients in clinical trials investigating novel therapies. The new test is produced commercially by Foundation Medicine and is expected to be available by the end of this year.

Medical oncologist Ross Levine, who led research at Memorial Sloan-Kettering contributing to the development of the test along with physician-scientists Marcel van den BrinkAhmet Dogan, and Scott Armstrong, presented results demonstrating its accuracy today at the annual meeting of the American Society of Hematology in New Orleans.

A Tool with Broad Impact

The test will play an essential role in the clinical care of most patients with blood disorders at Memorial Sloan-Kettering and, it is expected, in the care of patients throughout the United States. According to the Leukemia and Lymphoma Society, an estimated 1.1 million people in the nation are currently living with, or in remission from, leukemia, lymphoma, and myeloma, and an estimated combined total of more than 148,000 will be diagnosed with one of these diseases in 2013.

“Our hope is that this test becomes available to all patients in the country with these malignancies,” Dr. Levine says. “We were particularly excited that we weren’t just developing a tool for the relatively small number of people who are treated at our institution, but providing access to state-of-the-art cancer genomics more broadly.”

The diagnostic test was developed and validated using more than 400 samples from Memorial Sloan-Kettering patients with the three blood disorders. Dr. Levine explains that it is far more comprehensive than existing tests, which focus on a small number of genetic mutations associated with specific blood cancer types. The new test analyzes more than 400 cancer-related genes, and unlike most standard tests, it looks for alterations in both DNA and RNA.

Sequencing RNA along with DNA is especially useful in the detection of certain kinds of genetic alterations that commonly occur in blood cancers. These include translocations (which occur when pieces of DNA are exchanged between two chromosomes) and fusion genes (new genes that include parts of two different genes). In addition to improving the treatment of patients, Memorial Sloan-Kettering will use information gleaned from the test to further advance research into blood cancers.

Clinically Relevant Mutations

Dr. Levine explains that Memorial Sloan-Kettering researchers worked with Massachusetts-based Foundation Medicine to annotate, or define, every gene in the panel to correlate it with clinical data and to provide insight into how this information can be used to guide clinical decision making.

“What’s vital about the test is that it’s not just reporting the presence of specific alterations but also indicating how a particular genetic event detected in a patient can guide either prognosis or therapy,” he says. “We identified clinically relevant mutations that were not found using standard tests. These mutations are ‘actionable,’ meaning that targeting them can change the course of the disease, including directing patients to innovative clinical trials.”

Initially, the goal for the test is to produce the full genetic profile from a patient sample within three to four weeks. “With the exception of someone who has very acute leukemia that requires immediate treatment decisions, this test is going to be valuable in clinical care,” Dr. Levine says.


Vapours from damp buildings may trigger Parkinson’s

A vapour known as “mushroom alcohol” which is present in damp, mouldy buildings can damage the nerve cells of the brain responsible for Parkinson’s disease, scientists said.

A study has found that the compound, called 1-octen-3-ol, leads to the degeneration of two genes involved with the transport and storage of dopamine, the neurotransmitter in the brain that is lost in patients with Parkinson’s.

The researchers suggest that the volatile substances given off by mildew and other fungi growing in damp houses may be a significant risk factor in the development of the degenerative brain disease, which is thought to have environmental as well as genetic causes.

The study was carried out on the dopamine system of fruit flies, a recognised animal “model” of Parkinson’s disease, and the researchers calculated that mushroom alcohol was more toxic to these specialised nerves than benzene – a poisonous chemical known to cause genetic damage.

“These findings are of particular interest given recent epidemiological studies that have raised the concern of neuropsychological impairments and movement disorders in human populations exposed to mouldy and water-damaged buildings,” the scientists said in the study published in the journal Proceedings of the National Academy of Sciences. “Increased incidence of Parkinson’s disease is seen in rural populations, where it is usually attributed to pesticide exposure. However, the prevalence of mould and mushroom in these environments may provide another plausible risk factor for the development of Parkinson’s disease.”

Until recently, the search for environmental factors that could trigger the disease has focused largely on man-made chemicals, such as pesticides. However, natural compounds could be equally to blame, said Arati Inamdar of Rutgers University.

“There have been studies indicating that Parkinson’s disease is increasing in rural areas, where it’s usually attributed to pesticide exposure. But rural environments also have a lot of exposure to moulds and other fungi, and our work suggests that 1-octen-3-ol might also be connected to the disease, particularly for people with a genetic susceptibility to it,” she added.

Joan Bennett, co-author of the study, said she took an interest in the role of fungi in health after she became ill working in her flood-damaged house in New Orleans after Hurricane Katrina in 2005.

“I knew something about ‘sick building’ syndrome, because I am an expert in toxic fungi. I didn’t believe in it, because I didn’t think it would be possible to breathe in enough mould spores to get sick,” Professor Bennett said.

But when collecting samples while wearing protective gear, she fell ill. “While I was doing the sampling, I felt horrible – headaches, dizziness and nausea. I had a conversion experience,” she said.

Claire Bale, a spokesperson for Parkinson’s UK, said that the cause of Parkinson’s disease is one of the big unanswered questions.

“We already know that exposure to some chemicals can slightly increase the risk of Parkinson’s, and this is the first study to suggest that chemicals produced by fungi may play a part,” Ms Bale said.

“It is important to remember, this study was conducted using tiny fruit flies, so before we can really be confident about this new connection we need to see evidence from studies in people,” she added.

Feds Investigate Antipsychotic Prescribing in Children.

The US Department of Health and Human Services’ Office of Inspector General (OIG) has launched a probe into the prescribing of atypical antipsychotic medications to children under Medicaid.

“We will determine the extent to which children ages 18 and younger had Medicaid claims for atypical antipsychotic drugs during the selected time frame,” the office said in a summary of the plan.

“On the basis of medical record reviews, we will also determine the extent to which the atypical antipsychotic drug claims were for off-label uses and for indications not listed in one or more of the approved drug compendia.”

The time frame is a 6-month period from January to June 2011, when 84,654 children were prescribed antipsychotics in the 5 states selected for the probe, where Medicaid prescriptions are the highest — California, Texas, Illinois, New York, and Florida — said OIG spokesperson Donald White.

Psychiatric experts have been recruited to evaluate approximately 700 of the medical records as part of the ongoing effort, White told Medscape Medical News.

“We are currently conducting the medical record reviews, and the probe will likely last several months, possibly into 2014,” he said.

Lack of Funding for CBT

The probe is focusing on atypical antipsychotics such as aripiprazole (Abilify, Otsuka Pharmaceutical Co., Ltd.), risperidone (Risperdal, Ortho-McNeil-Janssen Pharmaceuticals, Inc.), quetiapine fumarate (Seroquel, AstraZeneca Pharmaceuticals LP), and olanzapine (Zyprexa, Eli Lilly and Company).

A previous probe by the OIG on the overuse of antipsychotics in nursing homes, which resulted in action by the Centers for Medicare and Medicaid Services (CMS) to reduce the use of the drugs by 15%, was launched in response to a request from Congress; however, the new probe was launched by the OIG itself, White said.

Concern over the overprescribing of antipsychotics to children in the Medicaid program is not new — a 2004 study found that children in the healthcare system from low-income families were 4 times as likely to be prescribed antipsychotics as those who were privately insured.

As reported by Medscape Medical News, a more recent study showed that the use of antipsychotic medications among Medicaid-insured children from low- or very-low-income families soared 7-fold to 12-fold between 1997 and 2006.

Among side effects of concern associated with atypical antipsychotics are weight gain and diabetes, and little is known on the long-term neurologic effects of the drugs used in early childhood.

One important reason why the prescribing of antipsychotics to children is believed to be higher among children under Medicaid coverage is that the system simply is not as accommodating to the best-known alternative — cognitive-behavioral therapy, according to Pensacola, Florida–based child psychiatrist Scott R. Benson, MD.

“The reimbursement for the kind of cognitive-behavioral therapy that could help these children is lower with Medicaid, so children who are covered by private insurance may have access to a better range of therapies,” he told Medscape Medical News.

“But part of this is our own fault on a professional level — we [psychiatrists] have not made a good enough case for the value of psychotherapy in helping children,” added Dr. Benson, who is a member of the American Psychiatric Association.

Infants, Toddlers Prescribed Atypicals

Dr. Benson said clinicians too often associate the option of cognitive-behavioral therapy with being arduous and time-consuming.

“The patient doesn’t necessarily have to be coming in 3 times a week over 10 years — there is plenty of evidence showing, especially for children who have been traumatized, that even short-term therapy, maybe once-a-week visits over 20 weeks, can be a very effective treatment.”

Among the more alarming figures regarding prescribing atypical antipsychotics to children are those showing prescriptions to the very young, including toddlers and infants.

As reported in a recent article in the Wall Street Journal, the inspector general’s 5-state probe found 482 children aged 3 years and younger who were prescribed antipsychotics during the 6-month period in question, including 107 children who were aged 2 years and younger.

Six children prescribed the drugs were younger than 1 year, and 1 was listed as being 1 month old.

Importantly, the records did not identify the diagnoses involved, and Dr. Benson speculated that some may have included children with certain severe disorders, such as autism.

“It’s important to remember that the majority of these prescriptions are not even written by child psychiatrists,” he said. “In the case of the very young children, these may have represented prescriptions from neurologists who were treating patients with severe autistic disorders.”

Quick Fix?

Others, however, may have been practitioners such as pediatricians, who, facing heavy patient loads, are often under pressure to make a quick diagnosis and reach for a quick fix — an antipsychotic.

“A practitioner may observe a few behaviours, say ‘that’s terrible,’ and simply prescribe something the patient doesn’t really need because there wasn’t enough time or interest in doing the kind of good, standard evaluation that all of us would expect for our children,” Dr. Benson said.

“Certainly all patients deserve that, regardless of their insurance situation.”

A complex range of psychiatric issues may cause a child to appear dysregulated, and a full evaluation is essential before writing that prescription, said Mary Margaret Gleason, MD, an assistant professor in child psychiatry and pediatrics at Tulane University in New Orleans, Louisiana.

“Especially in younger children, the causes of impulsive or disruptive behaviors can be quite broad,” she toldMedscape Medical News.

“A thorough assessment looking into psychological, environmental, and biological factors that might cause someone to look impulsive and disruptive needs to be done to know what is driving the impulsivity.”

“One of the biggest things that needs to be looked at, for instance, is if the child has been exposed to trauma, and if someone is considering using a medication that has as long a list of potential side effects as atypical antipsychotics, they do need to really be certain of what they’re treating first.”

Source: Medscape/com


The Rising Threat of West Nile Virus.

Mosquito bites are the scourge of everyone’s summer. The rising risk of West Nile virus that comes with the bites just makes them that much worse.

The last few years have seen outbreaks of West Nile in different locations around the country, so researchers at the Centers for Disease Control and Prevention and the U.S. Public Health Service recently did a review of the scientific literature on the mosquito-borne virus.

“I did a similar literature review ten years ago in JAMA,” Lyle Petersen, corresponding author on the study, told TheDoctor. Since that time, he went on to say, researchers have learned a lot more about the virus and how it behaves in the U.S..

The virus is able to establish itself in a wide variety of ecosystems, leaving the whole continental U.S. basically at risk.

A lot of people have been infected, and most likely, more than 1 million people have been made ill from West Nile virus, the scientists found. This is quite a high rate of transmission for an imported mosquito-borne virus coming into the country for the first time, Petersen, who is the director of the Division of Vector-Borne Diseases at the CDC, said. Mosquitoes are the most common, but not only, way the virus is transmitted.


According to Petersen, even though about 3 million people have been infected, 98 percent or 99 percent of the population is still susceptible to infection with the virus, so prevention methods are just as important as ever.

About 1 in 5 people who are infected will develop a fever with other symptoms such as headache, body aches, joint pains, vomiting, diarrhea, or rash.

The CDC estimates that most people (70-80%) who become infected with West Nile virus do not develop any symptoms. About 1 in 5 people who are infected will develop a fever with other symptoms such as headache, body aches, joint pains, vomiting, diarrhea, or rash. Most people with this type of West Nile virus disease recover completely, but fatigue and weakness can last for weeks or months.

Less than 1% of people who are infected will develop a serious neurologic illness such as encephalitis or meningitis (inflammation of the brain or surrounding tissues). Severe neurological symptoms can include headache, high fever, neck stiffness, disorientation, coma, tremors, seizures, or paralysis.

People with certain medical conditions, such as cancer, diabetes, hypertension, kidney disease, and people who have received organ transplants, are also at greater risk for serious illness. Recovery from severe forms of the disease may take several weeks or months. Some of the neurologic effects may be permanent. About 10 percent of people who develop neurologic infection due to West Nile virus die.

Location, Location

The researchers found that the virus has become widespread, and is now circulating every year across almost the entire continental U.S.. That West Nile has managed to cause outbreaks in places like Phoenix, a city in the middle of the desert and also in cities with completely different climates, like Chicago or New Orleans, is “pretty remarkable,” Petersen said. The virus is able to establish itself in a wide variety of ecosystems, leaving the whole continental U.S. basically at risk.

We expect that the number of cases, based on historical precedence, will begin to increase over the next several weeks.

Certain areas of the U.S., such as California and the Midwest, seem to be at higher risk for having sporadic outbreaks; however, outbreaks have occurred in many different places across the country, and some of them, such as Phoenix, are quite surprising. It is still very difficult to predict where outbreaks will occur, and they can happen anywhere.

The timing of outbreaks is amazingly consistent from year to year. They begin to increase at the end of July, peak somewhere around the beginning to middle of August, and then taper off into September. And they occur a little earlier in the southern U.S. than the northern region of the country. “This means that we expect that the number of cases, based on historical precedence, will begin to increase over the next several weeks, which means that people need to take precautions right now.” according to Petersen .

Some of the emergency control efforts that cities have taken, such as widespread pesticide spraying, are effective in stopping outbreaks when they do occur, says Petersen. Several studies have looked at the health effects of pesticide spraying, and found that there have been no short-term health effects from spraying to control West Nile outbreaks.

Don’t Be Bug Bait

Mosquitoes that spread West Nile virus are most active around dawn and dusk, although they can be out all night. If you go outside where mosquitoes are present, wear insect repellent. That is the single most important thing someone can do.

“We recommend products that contain N,N-diethyl-meta-toluamide, commonly called DEET,” says Petersen. “A lot of misinformation exists about DEET. People think it is dangerous. The reality of DEET, though, is that is actually one of the safest chemicals that people apply to themselves.”

If you go outside where mosquitoes are present, wear insect repellent. That is the single most important thing someone can do.

DEET-containing products are also much more user-friendly than they used to be, says Petersen. People think of them as oily and bad-smelling. But newer products are much more pleasant to use.

Petersen says that the higher the concentration of DEET, the longer it lasts, until the concentration gets up to about 40 percent. “I wouldn’t advise products that are 100 percent DEET, because they really do not work any better. You should look for products that contain 10 percent DEET if you are only going to be out for a short time, and 30 to 40 percent DEET if you will be out for longer periods.”

“We also recommend products that contain picaridinoil of lemon eucalyptus, orIR3535,” says Petersen. These products are registered with the EPA and are known to be effective. It is easiest to remember DEET, though, and physicians and public health officials have the most experience with DEET.

Source: JAMA

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