Dengue Fever: Know Your Facts

The beginning of summer brings blessed rainfall to the Caribbean, a welcome gift to the abundant flowers, but it can bring annoyances, as well, such as Aedes aegypti. Sound like an alien descending upon earth? Maybe not quite, but close. It is a mosquito, the most common species that invades our tranquility, and it transmits the dengue virus. Aedes aegypti is a daytime biter living close to island towns. So you can be bitten by an infected mosquito while hiking to the farmers market or during a leisurely morning walk. You may never even see or feel the bite. Such was the case when both our young children

fell ill in peaceful Bequia.
     We had just dropped the hook in soft sand, in the late afternoon, when our sons, Adam and Warren, needed to stretch their legs after having been on passage for most of the day. To starboard lay the perfect setting for two rambunctious boys: a long ribbon of white sand fringed in mango trees, near a creek-bed. We set off immediately in the dinghy, and soon they were absorbed in their normal Huckleberry Finn style of play — exploring the tropical bush to create mock battles, imaginary hunts, or light sport. This day, their activity was to see who could land the most mangos for me, using pebbles collected from the nearby creek to knock fruit from the treetops. Little did I know how that choice of setting would turn our lives upsidedown shortly thereafter.
     Bright sunlight burst through the hatch the following morning to announce the arrival of dawn, surprising me awake. Odd — usually my husband Peter and I are awake early. This morning was altogether different. Both boys were limp in bed with high fevers. Since they had been fully immunized against tropical diseases like hepatitis A and B, typhoid, yellow fever and the tetanus-diphtheria/measles booster, we weren’t too worried. We assumed, wrongly, that they had the flu. Frequently, we’ve contracted viruses and bacterial illnesses from arriving tourists who swoop down for some good old-fashioned island cruising of their own.
     Soon our sons’ fevers were followed by severe headaches and joint pain. Neither would eat. A rash appeared on their torsos with deep red splotches that I thought was prickly heat due to the high humidity. But when there was no improvement after three days, I became alarmed, considering for the first time that we were dealing with something far more serious.
     We made a bee-line to the emergency room, and the boys were diagnosed with dengue fever. I knew nothing about it! A simple blood test can tell you — request it. It was a month before our sons’ health returned and they resumed their normal activity level.
     Don’t let my tale bring you despair. We all want to continue cruising these island jewels of the Caribbean with peace of mind. Here’s what you need to know to arm yourself with accurate knowledge, and take proper precautions.

It is a viral disease transmitted by the infected Aedes aegypti mosquito. It has bitten an infected person, then you. It is usually a daytime biter, but can hide in clothes, behind curtains, or inside cupboards onboard your boat, coming out at night for a good feed. Symptoms include:

a rash of small red spots which appears three to four days after the onset of fever.
A simple blood test can confirm an accurate diagnosis, but there is no specific treatment for dengue, except to replace lost fluids and treat possible vein collapse from the more serious form of dengue hemorrhagic fever. (More on that later.) Recovery, characterized by fatigue, can take up to a month. To recover, take your boat to a secluded anchorage with a stiff breeze, and rest. Forget those boat projects. Give your busy social life a short break. And stay away from towns.

   Dengue is actually four viruses, not one, and once you’ve recovered from one type, you are immune from that particular serotype only. Your resistance to the other serotypes is partial and transient.
Once you’ve come down with dengue the first time, you are more susceptible to contracting DHF, dengue hemorrhagic fever, and the dangers can be greater from the secondary infection. With DHF, your immune system is suppressed. It can be potentially fatal, so drink, drink, drink, and get to a doctor quickly for a blood test. If fluid loss is not replaced, you can die from circulatory failure because of the collapse of blood vessels.
     How do you know if you have DHF? Symptoms are:

     Without prompt treatment, you can go into dengue shock syndrome (DSS) or circulatory failure.
     If you suspect you have any form of dengue fever, do not take aspirin. It can impair blood clotting. Take acetaminophen instead.
     The good news is: dengue fever and DHF are easily treated in early stages by a doctor. Fluids are administered to replace lost fluids; transfusions to control bleeding.
     Our sons slowly recovered from dengue fever, but Warren, our youngest, later came down with the more serious stage, the horrifying DHF. In the intervening time, he’d grown from a young boy living on our boat in the Caribbean, to studying and working in the Caribbean Basin.
     Last week, his e-mail informing us of his serious bout with DHF sent my husband and me to our knees. At the time, we were on passage in Scud, our 44-foot catamaran, and were unable to help him. Did he know the possible dangers of DHF, I wondered. I hadn’t informed him. My calm reserve turned to pure jelly. I grew frantic, knowing that ten percent of the cases of DHF are fatal.

     Fortunately, Warren wasn’t alone. His traveling companions, familiar with dengue in the area, rushed him to the local clinic. Alert medical staff diagnosed him with DHF, with previous signs of dengue. He was well in no time, with time to spare to recover from fatigue.

     There is no vaccine at present to prevent dengue, so you must take precautions. Aedes aegypti is smaller than most other mosquitoes, is black in color and can be distinguished by the white spots on its body and white rings on its legs.
     Cruisers may not be aware of a dengue outbreak, since we are often rushing to make our way south for the hurricane season. Also, not all Caribbean nations report outbreaks, or they may be delayed in reporting.
         When going ashore, wear light-colored clothing with full-length pant legs and sleeves. Mosquitoes are attracted to dark clothing and it makes mosquitoes nearly invisible.
        Also when going ashore, use insect repellent with

[Editor’s note: Mary Beth Ellison, MD, wrote in the June 2005 issue of Compass: “No definitive studies have been done regarding safety in children with DEET, so exercise caution when using this on them. DEET is toxic when ingested, can cause blistering in high concentrations, and should never be used on open or abraded skin. Application to a child should be done by the parent, being careful to avoid the face, eyes, and mouth; it should never be used on infants. All users should wash their hands well following application, and avoid inhaling any preparations with DEET.
“[In] 2005 the CDC announced the licensing in the US of two “new” chemoprophylactics. One is Oil of Eucalyptus,… It has not been approved for children under three years of age, and its duration of efficacy is notably shorter than standard products. The other product is Picaridin, also known as KBR3023. This chemical has been used in Europe and Latin America for years, and has an efficacy similar to DEET. The new product marketed by Cutter is called Advance; the one used in Europe is known as Autan.”]

     Stay anchored in breezy locations in harbors. Especially, avoid anchoring in front of towns, where forgotten old tires, bottles, or containers of water are virtual party pools for breeding mozzies.
      Sift through belongings onboard to shake out lingering mozzies that might have sneaked aboard. (I’ve discovered them many times, often never first hearing their ubiquitous whine.)
      Screen your boat hatches, portholes and companionway. You can buy one of those cool-looking mozzie nets for your berth that drapes like a tent across the mattress. They’re easy to install overhead. Better yet, don’t wait; throw one together yourself. Mozzie screen is sold by the meter in hardware stores. I hand-sewed mine, with bits of fabric lying around the boat and some Velcro, in a couple days. Some boutiques sell the lightweight mozzie nets for your berth.
      If you are chartering and only in the Caribbean for a brief time, report your recent return from the West Indies to your doctor, if you happen to fall ill back home. Medical staff can act quickly to avoid time-consuming exams, and thus prevent possible advanced stages of dengue fever or DHF.
     We’ve cruised the Caribbean for 20 years with rarely any illness. Armed with information about dengue fever and DHF, I can continue exploring these gems for many years to come with pleasure.