Practical Information on Dengue Fever by vmarcelo


									Practical Information on Dengue Fever
Especially for people who have had one infection and are worried about getting a second, more serious one.
By Art Ludwig, from an interview with Inid Garcia, Center for Disease Control, Puerto Rico 1/11/03 My family and I came down with Dengue fever while working on water, sanitation and health care for an Indian village in Michoacan, Mexico. Search on the internet and it is easy to find out that if you've had dengue before, you're at higher risk for contracting dengue hemmoragic fever and dying a gruesome death. Numerous authorities give the good advice to "avoid getting bit by the dengue transmitting mosquito." The mosquito bites primarily during the day, but if it's still hungry, it will bite at night, too. If you're not in a bee keeping suit with DEET all over it, day and night (unlikely, considering most places where there is dengue it is hot), there is a chance you might get bit again. So what do we do now—avoid visiting any tropical place ever again? What if you do get bit again, despite precautions? It was very difficult to find out what the actual odds of getting DHF are, and what to do if you do get dengue again. Inid Garcia, from the Center for Disease Control in Puerto Rico (where 80% of people have had classic dengue) was the only person I found who seemed to know anything—in fact, she seemed to know everything about Dengue. Here's some general info on dengue, followed by the excellent practical advice she shared with me. General info on Dengue See this site for much more general info: In 1997, dengue is the most important mosquito-borne viral disease affecting humans; its global distribution is comparable to that of malaria, and an estimated 2.5 billion people live in areas at risk for epidemic transmission. Each year, tens of millions of cases of dengue fever occur and, depending on the year, up to hundreds of thousands of cases of DHF. The casefatality rate of DHF in most countries is about 5%; most fatal cases are among children and young adults. Dengue and dengue hemorrhagic fever (DHF) are caused by one of four closely related, but antigenically distinct, virus serotypes (DEN-1, DEN-2, DEN-3, and DEN-4), of the genus Flavivirus. Infection with one of these serotypes does not provide cross-protective immunity, so persons living in a dengue-endemic area can have four dengue infections during their lifetimes. (Note: it is the subsequent infections which are much more severe.) Dengue is primarily a disease of the tropics, and the viruses that cause it are maintained in a cycle that involves humans and Aedes aegypti, a domestic, day-biting mosquito that prefers to feed on humans. Infection with dengue viruses produces a spectrum of clinical illness ranging from a nonspecific viral syndrome to severe and fatal hemorrhagic disease. Important risk factors for DHF include the strain and serotype of the infecting virus, as well as the age, immune status, and genetic predisposition of the patient.

What are odds of getting and dying of hemmoragic or shock dengue if you've had dengue and you get it again? DHF usually results in a second infection from a different serotype. The theory is that antibodies to one serotype help other serotype viruses do worse damage. Less then 10% of people who get dengue get DHF. 95% of this 10% are second infections. Your chance of DHF on a 2nd dengue infection are about 10%. Your risk of dying from DHF with inadequate treatment is 10--15% Your risk of dying with adequate treatment is less than 1%, regardless of age group. In the majority of cases, the actual cause of death is dehydration from internal bleeding, not hemorrhage. Precautions for people who've already had dengue If you are returning to a dengue area after already having had dengue, you're at greater risk. Avoid getting bit, and research beforehand a physician, clinic, or hospital which you trust to give you adequate treatment should you develop DHF. If you are in endemic areas as part of a development program and you're far from major medical care (as we are), see if you can include part or all of the elements of a "dengue mini-clinic" in your program (see below) so you can monitor your own or other dengue cases locally. Small dengue clinic list This list is of equipment for monitoring for possibly emergent DHF in a non-hospital setting, to determine if hospitalization is necessary or not: Hematicrit centrifuge Platelet count equipment Syringes Blood pressure gauge Thermometers, children, adults IV fluid & setup Normal saline solution Ring Lacerate. Monitoring dengue patients for onset of DHF If you can, get a platelet count, blood pressure, and hematocrit at the onset of regular dengue symptoms, as a baseline. Usually people who develop DHF do so after the fever goes down, not during first couple days. Hemorrhage -can be during 6-7 days, or later. It is most critical to monitor closely during the 24-48 hours after the fever goes down. Hemorrhage, declining platelet count, or climbing hematocrit are all warning signs that DHF may be developing and you should head towards your medical backup/ hospital. If you're far from hospital, go early. Hemorrhage by itself does not mean go to hospital if it is not severe. You can have dengue and mild hemorrhage without it being considered DHF.

Typical hemorrhage is nosebleed, gum bleed, small red dots in skin (pitequeas), and vaginal bleeding. Less common are vomit with blood, blood in stool. Transition from dengue to DHF can happen pretty fast...hours, not days. Platelet count --less than 100,000 = part of definition of DHF OR Decreasing daily platelet count and increasing hematocrit •Get hematocrit, platelet count when fever starts for baseline. •Keep monitoring daily. If it goes up by 20% from what they had, indicates hemmoragic fever, but don't want to wait this long. •Do daily/ 2x daily hematocrits, if increasing, leaking of the capillaries. •Attend to the patients overall state of well-being. •Check blood pressure. If it is falling, then need more fluid, possibly IV. Dehydration —Main characteristic of DHF is that people dehydrate faster, through capillary leakage •Body feels dehydrated, get collection of fluids in other places, such as lungs, abdomen. If not adequately treated, dehydration is what kills people (shock from loss of fluid), not the hemorrhage. Give a lot of fluids Can hydrate adequately just from drinking in most cases. Shock related symptoms Dengue shock symptoms which indicate that the patient should go to a hospital immediately: •Severe abdominal pain as dominant symptom (worse than headache, pain in bones) •Change in mental status-does not respond, loses sense, can't wake up. •Drastic change in temperature •Severe vomiting If you have the equipment & know-how, it could benefit a severely dehydrated patient to provide IV fluids during transport if it is a long way to the hospital. Testing You need to send blood to a well-equipped Laboratory for dengue testing. Serotesting Serotesting (to see which of the four serotypes of dengue you've got) has to be done during the acute stage (1-5 days) of the illness to isolate the virus. Afterwards you won't be able to determine which serotype it was. The public health service in some countries do serotype analysis by area and outbreak. Thus, if you've been infected, you might be able to find out the likely serotype by asking around, even if it is too late to test yourself. IGM testing Will give let you know if you've had dengue or not, within 30 days of infection. IGG testing Ideally you wait for IGG testing (long term immunity). You can do this after 3 weeks. If you think (or know) you've been exposed to dengue years before, IGG testing will show if you still have the antibodies, and thus are at greater risk of contract DHF from a subsequent infection. If an infant has been exposed to antibodies via an infected mothers milk An infant who has been exposed to antibodies through mothers milk and still has them will react exactly the same as somebody who had dengue before. You can do an IGG test for infant, child after 30 days, to determine exposure via antibodies from an infected mother's milk. If a baby tests positive for IGM, they had their own direct infection. Not all babies get IGG from breast milk. If they test negative for IGG, they will respond to a subsequent dengue infection as an initial infection, not as a more dangerous second infection. Retest baby after breastfeeding stops to see if he has own immunity, usually mom's antibodies only last 3-6 months. Classic dengue is generally milder in young people. Risk of fatality from DHF is the same across all age groups. More children contract dengue, possibly because they are outside more. At the hospital Should you rush to a hospital in another country? The care for dengue is relatively simple, and hospitals in endemic areas are probably more experienced with dengue than most hospitals in overdeveloped countries. If the facility is reasonable, the personnel reasonably competent, and the patient reasonably happy, it's probably best to stay put. An ideal situation might be a local hospital close to an airport. Adequate follow up in a hospital (or small dengue clinic if there is no alternative) • Frequent (daily or twice daily) platelet count, hematocrit, blood pressure. • Adequate but not excessive hydration, IV if necessary. • Monitoring of patient well-being Before discharge •Platelet count Must have stable or increasing platelet count of at higher than 50,00 (below 50,000 risk of spontaneous bleeding is higher) •Blood pressure

Stable blood pressure (shows good hydration) •Hematocrit Stable or falling (indicative of low or no hemorrhage) •Pass 48 hours without fever •No vomiting •Doesn't have respiratory distress From fluid in lungs. •Improved general constitution

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