Why platelets reduce in dengue?

Are you tired of hearing about mosquitoes and their bite being the only reason behind dengue? Well, brace yourself for some new-found knowledge about dengue. One major symptom that often goes unnoticed is a drop in platelet count. But do we know why?

The Role of Platelets

Before diving into the central idea behind reducing platelet counts, let’s first get an overview of what platelets are and how they function.

Platelets are tiny blood cells produced by bone marrow which help stop bleeding by forming clots. These clotting agents distribute proteins that activate further components to create a mesh-like structure as a response to injury or damage.

In cases where high amounts of damage occur in your body due to any disease such as burns, surgery, infections like dengue etc., maintaining an adequate level of platelets becomes more important than ever.

So when someone suffers from diseases like dengue fever- wherein there seems to be no immediate physical injuries or damages- sudden lowering down of platletes comes out as paradoxical reasoning making experienced doctors “scratch their heads”.

Let’s break this puzzle piece by piece:

Determining Low levels

It is normal for our bodies’ systems continuously replace old dying red blood cells with new ones via looped recyclage including white blood ceels( WBCs) and also plates (PLTs).

During diagnostic labs ,the range between 150K/UL -450K/UL PLTs(i.e Per U/Liter; mL) is considered ‘normal range’.

A reduction below this range signifies “thrombocytopenia” indicating low cell production or increased consumption/destruction typically caused during bleeding disorders, immune related ailments & cancer treatments.

However it has been observed patients suffering from viral fevers especially DENV/DHF(in layman terms-Dengue fevervirus) present with much more reduced platelet counts, sometimes as low as even 10K/UL coming close to thresholds of alarming bleeding-risk(later-on discussed).

Studies estimate nearly a third of dengue infected individuals may have thrombocytopenia.

Understanding the mechanism

Now that we know what thrombocytopenia is, let’s look at how it happens in dengue cases.

Dengue virus first infects immune cells such as monocytes and macrophages. Research has shown that these infected immune cells release molecules known as cytokines (such as interleukin-1beta or tumor necrosis factor-alpha) which signal various other types of “defense” cells to multiply on their part— Human Platelets are oneof them! Here comes the fun ride. Some studies suggest the very same defense mechanism meant against eliminating viruses ends up attacking platelets too!

Yep, you heard it right – In layman terms(don’t tell your dr.) when Dengue encounters ordinary endothelial(sound technical ain’t it?) blood-vessel surface;these activated innocent defense-cells cling onto blood platelets forming clumps aiming to kill infectious invaders while ending up triggering severe shortage downstream for body’s own clotting agent-PLT supply chain.

What causes this response?

It has been observed that there are two different ways in which an individual can contract dengue- from primary infection by any one of four serotypes and secondary infection by another serotype after antibodies have already developed due to a previous infection.

Don’t get fooled thinking…’oh boy!yay.I had survived!.Let me hit muh guitar’ Unfortunately, during secondary infections with another strain usually a different antigenic sub-type , the stakes get higher, increasing chances for multiple shades i.e complex variety of mysterious systemic conditions (Here we go Again)[https://www.youtube.com/watch?v=3t-47e-a2rk]; one such being the drop in platelet counts.

While primary infections are usually mild and lead to more of a fever-like illness, secondary infections can be severe and lead to hemorrhagic shock or dengue fever.

The Role of Antibodies

A silver lining?

During a primary infection, IgM antibodies -the first antibody made by the body during an immune response against any foreign particle– fight off dengue virus with just one serotype . Over time igG-antibodies develop,detecting all other three-serotypes entering the system.

These circulating igG cells simply adhere onto new viral particles unrecognized and prepare host cells for defeating them; On paper this immunity sounds like real superhero stuff IN REALITY things get messy..

When Dengue strikes back again (like Katy Perry!)with any different strain/sub-type incapable of igniting previous set-up ‘immunity’ ,What happens is that unattached antibodies bind well with these infectants forming what scientists call “Antibody Dependent Enhancement”(ADE)complex leading to greater internalization inside vulnerable immune/target-cells (yawn! Sounds fatal)

The subsequent release if cytokines affects Immune cells along with unstable clumping leading to runaway killing spree endangering it’s own suppliers i.e PLts causing decrease upto potentially lethal levels wrt reducing blood coagulability/as needed for normal functioning/ healing/repair purposes—-and Voila!

So Should we stop IgGs delivery?

Not really as enforcing timely testing (allow treatment before ADE occurs),cross-matching antigens simultaneously reduces risk/vulnerabilities facilitating early interventions removing staleness/stigma/practicality gucks slowing current DX-treatment methods.


In summary, there seems to be no easy way out from Dengue(a mosquito borne disease). But understanding the mechanics of how Dengue lowers the platelet count helps us better understand how to treat and prevent complications. While there is no specific treatment for dengue, ensuring hydration and seeking medical attention could save lives.

And until we get that vaccine, let’s all just start being nicer to each other – because at least we can control that!

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