Note: The Pregistry website includes expert reports on more than 2000 medications, 300 diseases, and 150 common exposures during pregnancy and lactation. For the topic Dengue Fever, go here. These expert reports are free of charge and can be saved and shared.
There’s a fascinating new book about our battle with mosquitoes and their diseases—and it’s not written by a physician, but by a history professor. In “The Mosquito: A Human History of Our Deadliest Predator,” Dr. Timothy Winegard of Colorado Mesa University talks about how mosquito-borne diseases have affected us through the ages, and how the little buggers seem to be winning the war.
The lesson here is that we should pay attention to mosquitoes. And as is so often the case, if you’re pregnant, it pays to take extra steps to avoid disease. One such disease, eastern equine encephalitis, has been very much in the news, particularly in the Northeast. Let’s look at another malady transmitted by mosquitoes: dengue.
Dengue is a disease due to any one of four viruses carried by the Aedes mosquito. The mosquitoes (and thus the virus) live in the tropics and subtropical areas—areas where about half the world’s population lives. Most people outside of these regions who become infected get the virus during travel. Regardless of where or how, however, it’s a big problem: about 390 million people worldwide contract the infection each year. And although people who are infected with a dengue virus become immune to that virus, because there are four strains, anyone can get dengue up to four times.
Mosquitoes and humans carry the dengue viruses. Humans become infected through bites of the female mosquito. In turn, they can transmit the virus to a mosquito that bites. Humans can also infect other humans—for example, through blood donation or breastfeeding.
So: what happens after infection? About three quarters of infected individuals will feel fine. However, about 3 to 14 days after acquiring the virus, others will begin to have symptoms. They’re pretty nonspecific—fever, headache, vomiting, rashes—but a couple of symptoms, particularly in combination with an outbreak or travel to an area known to have dengue, might give some clues. These include pain behind the eyes, severe muscle and joint pains, and a darker flat rash called petechiae.
After 2 to 7 days, most people start to improve. However, a small percentage of affected individuals will go on to get more severe disease. They’re quite sick: their multiple problems include bleeding and trouble breathing.
Dengue and Pregnancy
As you can see, dengue is something best avoided by everyone. But what if you’re pregnant? We didn’t have a lot of data until recently on any risks to an unborn child. That’s beginning to change. Researchers have turned to Brazil, which has a significant amount of dengue, to study the disease in pregnant women. Although women who contract the virus and have no symptoms haven’t shown a significant risk, in those who are symptomatic, the virus does appear to show evidence of being a danger to the fetus. Potential outcomes include miscarriage, stillbirth, low birth weight, and prematurity. In addition, a woman who becomes infected around the time of delivery can have a baby who goes on to have dengue symptoms.
Avoiding and Managing Dengue
Unfortunately, there’s no medicine out there that will prevent and treat dengue, and there is no vaccine in the United States. (Several other countries where dengue is more of a problem have rolled out a vaccine. It’s also approved for use in some U.S. territories.) The best prevention is controlling your exposure to mosquitoes! Certainly, avoidance of travel to areas with the virus is prudent, particularly for pregnant women. Those who live in or must travel to areas where dengue is present can take steps to protect themselves:
- When possible, eliminate standing water where mosquitoes can breed.
- Use an insect repellent containing the ingredient DEET. This is generally considered OK for pregnant women. Clothing can be sprayed with permethrin.
- Try to wear long-sleeved clothing.
- Stay and sleep where you have air conditioning and screens on the windows and doors. Mosquito netting for the bed is also helpful.
- If you have any concerning symptoms that might be dengue, let your providers know. And don’t forget to inform them of any recent travel.
As Dr. Winegard indicates, despite our best efforts to control mosquitoes and their diseases, they aren’t going away anytime soon. Indeed, we’ve seen some dengue in the southern 48 states in recent years, and there’s evidence that some “tropical” mosquito-borne diseases are beginning to show up in Europe. We don’t want anyone to become sick from this illness. But when you’re “avoiding for 2,” it’s especially critical to be armed with information for your battle.