The following originally appeared on The Upshot (copyright 2017, The New York Times Company) and is jointly authored by Aaron Carroll and Austin Frakt.
Long after the floodwaters recede, and even during cleanup and rebuilding, the people who lived through Hurricane Harvey will face another form of recovery — from the storm’s blows to physical and mental health.
The short-term health effects of floods capture our attention. Harvey has already caused dozens of deaths, and in 2005 Hurricane Katrinakilled more than 1,800 people.
Yet people endure injuries and illnesses in numbers that far exceed the death toll. When Hurricane Iniki hit Hawaii in 1992, injuries went up by a factor of six, and more than half those injuries were open wounds. Waterborne and communicable respiratory and gastrointestinal disease can spread amid the breakdown in water sanitation, contamination from industrial or hazardous waste sites, or the higher density of people crowding into shelters.
A systematic review published just months ago showed how various phases of flooding and storm disasters affect health. Researchers found that wounds, poisonings and infections of the gut and skin increase soon after storms. Gastrointestinal infections increase more frequently after floods. Diabetes-related complications increase after both.
People with chronic conditions like cardiovascular disease or respiratory illness are particularly prone to health problems immediately after a storm, and their care can be complicated by lack of necessary medications or access to medical records. After Hurricane Katrina, one study found that 14 percent of emergency visits to health care facilities were to treat chronic conditions, and almost 30 percent of those seeking care were sick enough to warrant admission, which is much higher than average for emergency departments. An additional 7 percent of emergency visits were to fill medications.
Visits to the doctor for conditions such as asthma and heart disease also increased significantly after Hurricane Iniki. Harvey caused the shutdown of dozens of dialysis centers. Patients with kidney disease rely on dialysis several times per week, and missing even one session can have severe consequences.
But large floods and other natural disasters have longer-term physical and mental health consequences we’re less attuned to. Well after the event has faded as a top news story, victims continue to suffer and struggle.
A 2012 systematic review published in Environment International documented floods’ tolls on human health, also covering longer-term effects. Flood-affected areas can experience higher mortality rates for months. For example, after Hurricane Katrina, the mortality rate in the New Orleans area was 47 percent above normal for the first half of 2006, up to 10 months after the storm. After Iniki, the mortality ratefrom diabetes went up significantly in the year after. Heightened rates of chronic illnesses can persist in flooded areas for decades.
Many studies document a surge in mental health diagnoses in populations that experience floods. These, too, can last years. Six months after floods in Mexico in 1999, a quarter of the affected population still had symptoms of trauma or depression. Increased rates of both could still be detected two years later, particularly among those among those who had experienced the worst aspects of flooding: flash floods, mudslides, the witnessing of injury or death, and displacement.
Similarly, months after floods in Thailand and South Korea, those with more harrowing experiences were four times more likely to have symptoms of post-traumatic stress disorder or depression.
In a post-Katrina assessment, the Centers for Disease Control and Prevention found that though a quarter of respondents lived with someone who needed mental health counseling, fewer than 2 percent received it. Another C.D.C. assessment found that one-fifth to one-quarter of New Orleans police officers had symptoms of P.T.S.D. or depression three months after the flood. Other analyses showed that suicide rates spiked in New Orleans in this period and that rates of P.T.S.D. among workers there were high.
Floods can also have lasting effects on infants and children. With access to obstetric services challenged during and after a flood — as well as negative effects on pregnant women’s physical and mental health — researchers have found worse pregnancy outcomes in flooded areas. One study of women who became pregnant in the six months after Hurricane Katrina found that exposure to the hurricane was associated with earlier delivery and delivery of a lower-weight infant. Another study of pregnant women exposed to flooding in North Dakota in 1997 had similar findings, but also found increased risks to the mother, including anemia, eclampsia and uterine bleeding.
Research tells us how we might respond to natural disasters like Harvey. Recommendations include public education about health effects and precautions, and improved surveillance programs to detect diseases or complications that usually increase after a disaster. They also include monitoring communities for mental health problems, then providing the services needed to care for them, and paying special attention to pregnant women. If you or those you know have been directly affected by Harvey, the C.D.C. has many helpful links on how to cope with a disaster or traumatic event.
Everyone is understandably focused on the immediate dangers from flooding. But analysis of previous natural disasters shows that Harvey’s survivors will need attention and care far into the future.
