Thrombocytopenia In Dengue Fever

Words by Sharwan Kumar Yadav

Dengue fever is a mosquito-borne viral infection that is on the rise in recent years in Nepal. It continues to be a significant global health concern, affecting millions of people annually.

One of the notable complications associated with dengue fever is thrombocytopenia – a condition characterized by a low platelet count. In this article, we will delve into the relationship between thrombocytopenia and dengue fever, exploring its causes, symptoms, and management.

Thrombocytopenia is one of the criteria used by WHO guidelines as a potential indicator of clinical severity of Dengue. The 2009 WHO guidelines define thrombocytopenia as a rapid decline in platelet count or a platelet count less than 150,000 per microliter of blood.

Platelets are the tiny blood cells responsible for blood clotting. They play a crucial role in preventing excessive bleeding. In case of dengue fever, thrombocytopenia occurs due to the virus’s ability to disrupt the normal functioning of platelets and the bone marrow, where these blood cells are produced.

Dengue virus directly targets and infects cells in the bone marrow, leading to a reduction in platelet production. The virus itself also triggers an immune response that can lead to increased destruction of platelets.

A kinetic description of platelet counts in dengue fever (DF) shows a significant decrease on the 4th day of the illness in which, platelet counts mildly to moderately decreased on the 3rd day until the 7th day of illness and reaches normal levels on the 8th or 9th day.

In children, there is little correlation between platelet count and bleeding manifestations or between platelet count and disease severity. In adults, a platelet counts of 5 × 109/L and packed cell volume >50 are significantly associated with bleeding manifestations. In dengue patients suggested that bleeding occurred more often in patients with platelet counts below 20 × 109/L.

Most clinical guidelines recommend that platelet transfusions be given to patients who develop serious hemorrhagic manifestations or have very low platelet counts, platelet counts falling below 10–20 ×109/L. The mechanisms involved in thrombocytopenia and bleeding during

Dengue virus (DENV) infection are not fully understood. Several hypotheses have been suggested to elucidate the mechanism involved.

Symptoms and Impact of Thrombocytopenia

Thrombocytopenia can result in several symptoms, which can vary in severity. Common symptoms include:

• easy bruising,
• spontaneous nosebleeds,
• gum bleeding, and
• petechiae

In severe cases, patients with dengue fever and thrombocytopenia can experience internal bleeding, which can be life-threatening if not promptly managed.

Diagnosis and Management

Diagnosing thrombocytopenia in dengue fever involves a blood test to determine the platelet count. On the basis of platelet counts the dengue patients can be categorized into the four categories based on their platelet count at the time of admission:

1. High risk
2. Moderate risk
3. Low risk
4. No risk

High risk patient

The patients belonging to this group have platelet count < 20,000/cumm and they are at high risk of bleeding. Such patients by the rule of the thumb should be receiving prophylactic platelet transfusion. The patients in this category whose platelet count is less than 10,000/cumm have an even greater risk and need to be prioritized in case of an epidemic or, in case of limited resources.

Moderate risk

All the patients whose platelet count is in between 21-40,000/cumm belong to moderate risk category. The patients of this risk group should be transfused with platelet only if they have any hemorrhagic symptoms.

Low risk

Those patients whose platelet count >40,000/cumm but <100,000/cumm for the age and sex should be observed and monitored carefully but should not receive unnecessary platelet transfusion because of the risk of transmission of blood borne infection (with no benefit of platelet transfusion).

No risk category

Patients falling in this category usually have the platelet count >100,000/cumm. They should never be transfused with platelet and should be managed on intravenous fluids and supportive therapy.

Dengue patients are often advised to maintain proper hydration, rest, and avoid certain medications that can exacerbate bleeding. This is the same reason why patients suffering from Dengue fever are only asked to take Paracetamol Tablets for fever and no other medications so as to decrease the risk of bleeding.

In severe cases, hospitalization may be required, especially if the platelet count drops significantly. Blood transfusions might be considered to raise the platelet count and prevent life-threatening bleeding episodes.

Platelet Transfusions

Dengue virus (DENV) infection can directly or indirectly affect bone marrow progenitor cells by inhibiting their function. Thrombocytopenia is a common cause of concern in dengue to both patients and attending clinicians. There are no clear guidelines for management of thrombocytopenia and platelets are ordered as a routine in most hospitals.

Prophylactic platelet transfusions are therefore given in dengue fever with thrombocytopenia to prevent hemorrhagic complications.

Although the use of prophylactic platelet transfusion is increasing in countries where dengue is endemic, it is associated with risks and has financial implication. Prophylactic platelet transfusions are basically the platelet transfusions given in the absence of clinical bleeding, in contrast to therapeutic platelet transfusions which are given to patients with clinical bleeding. There is controversy as to the efficacy of prophylactic platelet transfusions and the exact trigger for platelet transfusion in dengue.

 

Prevention and Awareness

Preventing dengue fever itself is the most effective way to avoid its associated complications, including thrombocytopenia. This involves controlling mosquito populations through measures such as eliminating breeding sites, using insect repellents, and wearing protective clothing.

 

Conclusion

Thrombocytopenia is a significant concern in dengue fever cases due to its potential to lead to bleeding complications. Understanding the relationship between dengue fever and thrombocytopenia is crucial for both medical professionals and the general public. Timely diagnosis, appropriate management, and preventive measures against dengue virus transmission are essential in mitigating the impact of thrombocytopenia and reducing the risk of severe bleeding episodes.