Dengue Fever

Dengue fever is a viral infection transmitted through the bite of an infected mosquito.  Because there are four different viruses, you can actually be infected multiple times with an actual dengue fever.  Here in Hawaii we do have the mosquito species (Aedes) that can transmit the virus, but the virus itself it not endemic to the area.  You cannot get Dengue from another person.

As there have been recent local cases of Dengue, you should be aware of the symptoms and ways to avoid getting bitten by infected (even unaffected!) mosquitos. 


Dengue Fever has a wide range of clinical symptoms, ranging from asymptomatic to severe.  Not to freak anybody out, but most Dengue infections in children under age 15 are without symptoms.  Adults are more likely to have the classic dengue symptoms of headache, muscle or joint pains or pain behind the eyes and sometimes a rash.  Patients can also have nausea, vomiting or diarrhea, or upper respiratory symptoms such as cough and sore throat.  These symptoms can appear 1-2 weeks, but as early as 2-3 days after the offending bite.  Symptoms can last for days to weeks. 

Some cases can progress to blood abnormalities, often seen as bleeding in the skin or nose or less commonly gastrointestinal tract.  These patients usually have a low white blood count and low platelet count and sometimes have abnormal liver enzymes. 

In severe cases, Dengue infection can progress to hemorrhagic fever, which is called such because of the spontaneous bleeding.  Yes, that sounds bad.  And it is. 

Technically, Dengue Hemorrhagic Fever may be classified as a different disease from Dengue Fever and has very specific diagnostic components, but it is a still a manifestation of the same viruses.  The increased vascular permeability can cause shock, and treatment is needed urgently.  Symptoms may include severe abdominal pain and vomiting, as well as increased lethargy in spite of resolving fevers.  Patients can have bloody vomitus, increased menstrual bleeding (during their period or even in between cycles), bloody stool, bloody nose or red spots and bruising on the skin for unknown reasons. 


Doctors can often diagnose Dengue based on symptoms or via blood tests.  Here in Hawaii, we’ll do a blood test because it’s not a common illness here and we’d need to confirm the diagnosis.  But in places where they are very familiar with the disease, you may not need the testing for the doctor to know what you have. 

Treatment is symptomatic, as this is caused by a virus – remember antibiotics do not fight viruses (read that post, please! 10/27/2015).  But severe cases may need to stay in the hospital or even get blood transfusions.


Ways to keep mosquitos away

Mosquitos love standing water, so rid yourself of this as you can.  Most of us cannot get rid of out catchment, but at least keep it covered.  Clean any containers that hold water, such as pet bowls or flower pots weekly to clear out mosquito eggs.  If you are outside, wear protective clothing, such as long sleeves and pants (easier said than done in Hawaii!) and bug repellant.  Unfortunately, only DEET or picaridin containing repellants are proven to keep the little buggars away, so use a formula containing 20-30% DEET or picaridin.  Don’t tell my aunt, who still swears by Skin-So-Soft, but since she’s not here in Hawaii at risk for Dengue, I’ll let that go.

Aedes mosquitoes are most active at dusk and dawn, so limit your potential exposures during that time.  Wear lighter colored clothing when you are out at those times, both for visibility and to avoid being mosquito-bait.

Always help children apply the bug repellant – prevent them from spraying it on.  Put it on your hands and then rub it on them.  Never put repellant on a child’s hands – it is very likely to end up in their mouth.  Don’t use a combination bug repellant/sunblock.  Review the post on sunblock (8/25/2015) to see how often you should be reapplying sun protection, and you’ll quickly overdose on the DEET, which doesn’t need the frequent reapplications. 


Protect yourself and your family, but if you’re worried your symptoms may be Dengue Fever, please make an appointment with your physician.

Man vs Machine (Online symptom checker)

We as physicians and medical providers have a love-hate relationship with the internet. I do really like my patients being more informed and being able to find information regarding their diagnoses. I do however, struggle with my patients coming in and telling me they’ve been “diagnosed” with this or that ailment, which, upon closer examination, actually is a self-diagnosis, perhaps with some assistance from well-meaning friends, TV commercials or Dr. Google.

Sometimes, it may be the correct diagnosis. But sometimes, an assumption about a diagnosis may lead us as clinicians down an incorrect path as we fail to consider the actual symptoms of you – the flesh and blood patient in front of us. We can get distracted by the facts as presented in what we learn in medical school to call the “past medical history.” I’ve always worried about this as a clinician, but now a study is here to tell me whether I should continue to worry or not.

Some people smarter than I reviewed 23 different online symptom checkers diagnoses for 45 standardized written patient scenarios provided to test medical students. The symptom checkers provided the correct diagnosis in 34% of the cases (interestingly, only 24% for emergent diagnoses only). They faired better when utilizing a top 20 possible diagnosis list, scoring the correct diagnosis within the list 58% of the time.
When the symptom checker’s purpose was to triage the symptoms (advise the patient on whether they needed emergent, non-emergent or self care), they actually did a bit better. When the situation was emergent, the symptom checker was correct with triage advice (remember – not necessarily diagnosis) 80% of the time. But the accuracy dropped off with the non-emergent (55% accuracy) and self-care (33% accuracy) scenarios and some of the programs actually always advised emergent care.

Currently, medical providers’ diagnostic accuracy rate appears to be 85-90% (hey, we’re all human!). An interesting comparison would have been to have some real life medical providers review the symptoms to see how we held up. I like to think I’m better than a computer, but can I objectively prove that I can make a diagnosis equally as well?
Also, would we humans be any better without being able to lay hands on our patient and do an actual physical exam? We humans have information the computers do not – medical history, medications, qualifying factors, and the very important physical exam. This makes a difference. As does our role in medicine – I suspect an ER physician vs a primary care physician might have similar capabilities regarding triage (I hope I know when I situation is emergent!), but different results regarding correct diagnosis depending on the nature of the ailment. We have different roles in the medical field and therefore different skill sets regarding diagnosis of common day to day maladies. Please don’t expect the ER doctor to use their brain space to know how to treat run of the mill urinary incontinence, but I would absolutely anticipate he could quickly distinguish between non urgent causes and life threatening ones (spinal compression, severe infection, seizure, etc). And if you have an acute heart attack or stroke, you definitely want their skills at hand as they will be the difference between whether you hug your kids at their next birthday.

All in all, the online symptom checkers appear to be able to give you a top 20 list of possible diagnoses when you input your symptomology. If you are willing to go through the treatment for each of those possible diagnoses in succession, not worry about missed diagnosis and want to save the copay, then the symptom checkers are worthwhile.
For me, I prefer to utilize my time with patients making sure we don’t miss something severe, then focus on the most likely cause of their symptoms. After a thorough history and physical exam, as needed. Take that, Computer!

Study Source: “Evaluation of symptom checkers for self diagnosis and triage: audit study,” BMJ, June 2015