The Dengue Saga: Mythbusters v2 | Platelets : How low art thee, let me count how (or should I?)

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QUESTION/S: Is decreased platelet count the only concern in dengue? Why are Herbal remedies adamant in their claims that they can raise a patient’s platelet count?

One of the most notable effects of dengue infections that the public is concerned about is the decreased platelet counts of patients. In fact, it is only one of, and possibly, may not be the most concerning among the myriad changes that our bodies undergo when fighting dengue.

A common misconception (that a decreased platelet count is the only concern) is also one of the reasons why various traditional or alternative regimens and capsules derived from these herbal medications are being advertised for their abilities to increase the platelet counts of patients.

But remember that in conventional medicine, treatment for dengue rarely even addresses the decreased platelets – and this factor is most often used as a diagnostic tool than a target of treatment.

But in the context of dengue fever, are platelets really that trivial? To discuss this, we first have to talk about some of the basic pathophysiology of dengue fever.

Dengue fever presents in a nonspecific manner similarly to that of many other viral and bacterial illnesses.

Fever typically begins on the third day of illness and persists for five to seven days, abating when the presence of the virus in the blood has disappeared.

Symptoms of dengue.  Image source: Centers for Disease Control and Prevention
Symptoms of dengue. Image source: Centers for Disease Control and Prevention

Fever may reach 41C° and occasionally, and more frequently in children, the fever abates for a day and recurs, a pattern that is termed a saddleback fever; however, this pattern is more commonly seen in dengue hemorrhagic fever and severe dengue.

Along with these events, while a decreased platelet count is often present, many viral infections and in some instances, the common cold, actually lower the platelet count in our bodies too. People take this for dengue, as symptoms are the same. Most of the folks would then want remedies for the lowered platelet counts when surprisingly experts have yet to actually determine a definitive reason for platelet’s role in dengue.

As far as platelets are concerned, This is what we currently know based on various research:

An October 2009 study by Martina BE and co-authors published in Clinical Microbiology Reviews state that the virus ultimately causes dysfunction of the bone marrow and its cells — which are essential in producing platelets – leading to its reduced numbers. Note that reduced platelet numbers contribute to increased risk of bleeding which may manifest as gingival bleeding or rashes.

More studies however found some significant correlation between platelets and the immune system, leading to various theories regarding the platelets’ roles in the disease. In a 2013 study by Hottz ED and co-authors published in the journal of Thrombosis and Haemastosis, they saw that dengue infection induces platelet activation, mitochondrial activation, and cell death (apoptosis). This means that the dengue virus may directly affect platelets and not only indirectly affecting them from the bone marrow by utilizing their roles in immunity.

Further studies in 2015 by Matthew T. Rondina and co-authors published in the American Society of Haematology, Blood Journals suggest that the dengue virus actually use platelets to replicate, or simply hitch a ride with in order to further disseminate and spread. Without elaborating the details on how this happens, the researchers theorize that the lowering of platelets may very well be the body’s own mechanism to rid itself of the disease.

A 2017 study by Meenakshi Kar and co-authors published in the Open Forum for Infectious Diseases, the “pirate” dengue virus claims of the 2015 study were further delved on to. Although dengue antigens have been observed in platelets, the study concluded that there is no strong evidence to suggest a direct infection of platelets by the dengue virus contributes to thrombocytopenia or lowering of the platelet counts. They showed that while the dengue virus can enter platelets and replicate as with the 2015 study, the replication is minimal to the point that it cannot produce an infective dose, and that some other immune mechanism is the reason why platelets are being lowered, is not exactly a defense mechanism by our bodies.

In a 2019 study by Chiao-Hsuan Chao and co authors published in Plo Pathogens, they found that dengue virus’ antigen, NS1 directly activate platelets through Toll Like Receptor 4, enhancing platelet aggregation, adhesion and phagocytosis by our body’s own immune cells. Basically the dengue virus attacks platelets by using its own immune system properties and make our own immune system attack it, a form of autoimmunity, which may contribute to the thrombocytopenia.

Most of these studies are but many of the countless explanations why platelets are significant in dengue Infections, but then our understanding of its mechanisms are incomplete. Some experts theorized that the lowered counts are our bodies own way of expelling the disease, some experts say it’s a direct attack from the virus.

Experts on the field continue to research on this. But ultimately, while platelets are indeed an important factor, it is not the only thing that is happening in dengue pathophysiology. Platelet counts are only part of the complete blood count which are one of the laboratory and diagnostic work ups in dengue, and each one (platelets, red blood cells, white blood cells, hematocrit, etc.) may very well have some interesting stuff happening in the molecular level a bit long to elaborate.

One other example that more often than not, goes hand in hand with a reduced platelet count in the laboratory panels of dengue patients is leukopenia or a reduced number of white blood cells specifically the lymphocytes, which may happen near the end of the febrile phase (for a refresher on the different phases Read: The Dengue Saga: A known Nemesis). With this, we can now ascertain that dengue, and any disease entity for the matter, is not limited to its single aspect but various factors that contribute to a whole, and is also different per individual.

That is why, while certain traditional regimens may claim to be cure alls, or tackle a specific aspect of the disease’ effects, it’s helpfulness may be overplayed.

QUESTION: Is decreased platelet count the only concern in dengue? Why are Herbal remedies adamant in their claims that they can raise a patient’s platelet count?

VERDICT: Platelet counts are significant in Dengue Fever BUT it’s not the only concern since it’s only one of the blood components that are affected. The more important thing, in our opinion, is to note that when physicians treat dengue, they do not actually address the decreasing platelets. Rather, treatment is based on maintaining proper fluid balance in the body to prevent dehydration or fluid overload and alleviating symptoms that come with dengue fever. Currently, there are currently no known antiviral drugs that are specific for dengue virus itself with a dengue vaccine only partially effective.

This now begs the question on how truly effective herbal remedies or capsules synthesized from herbal plants such as the “tawa tawa” is in their claims of preventing or treating dengue, since they are often pegged as platelet enhancers / protectors / regenerators, when in the first place, conventional dengue treatment is based on fluid balance and the alleviating of symptoms that come with it and not directly increasing platelet counts.

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