The white blood cells respond by producing several signaling proteins, such as cytokines and interferons, which are responsible for many of the symptoms, such as the fever, the flu-like symptoms, and the severe pains. In severe infection, the virus production inside the body is greatly increased, and many more organs (such as the liver and the bone marrow) can be affected. Fluid from the bloodstream leaks through the wall of small blood vessels into body cavities due to capillary permeability. As a result, less blood circulates in the blood vessels, and the blood pressure becomes so low that it cannot supply sufficient blood to vital organs. Furthermore, dysfunction of the bone marrow due to infection of the stromal cells leads to reduced numbers of platelets, which are necessary for effective blood clotting; this increases the risk of bleeding, the other major complication of dengue fever. Viral replication
Once inside the skin, dengue virus binds to Langerhans cells (a population of dendritic cells in the skin that identifies pathogens). The virus enters the cells through binding between viral proteins and membrane proteins on the Langerhans cell, specifically, the C-type lectins called DC-SIGN, mannose receptor and CLEC5A. DC-SIGN, a non-specific receptor for foreign material on dendritic cells, seems to be the main point of entry. The dendritic cell moves to the nearest lymph node. Meanwhile, the virus genome is translated in membrane-bound vesicles on the cells endoplasmic reticulum, where the cells protein synthesis apparatus produces new viral proteins that replicate the viral RNA and begin to form viral particles.
Primary gastric lymphoma (lymphoma that originates in the stomach itself) is an uncommon condition, accounting for less than 15% of gastric malignancies and about 2% of all lymphomas. However, the stomach is a very common extranodal site for lymphomas (lymphomas originate elsewhere and metastasise to the stomach). It is also the most common source of lymphomas in the gastrointestinal tract. Signs and symptoms
Symptoms include epigastric pain, early satiety, fatigue and weight loss. Most people affected by primary gastric lymphoma are over 60 years old. Risk factors
Risk factors for gastric lymphoma include the following:

Helicobacter pylori
Long-term immunosuppressant drug therapy
HIV infection

Pathophysiology
The majority of gastric lymphomas are non-Hodgkins lymphoma of B-cell origin. These tumors may range from well-differentiated, superficial involvements (MALT) to high-grade, large-cell lymphomas. Sometimes, its hard to differentiate poorly differentiated high grade B-cell gastric lymphoma from gastric adenocarcinoma clinically or radiologically, yet histopathology with immunohistochemistry is recommended to stain specific markers on the malignant cell that favor the diagnosis of lymphoma. Immunohistochemistry stains specific clusters of differentiation that are present on B-cells like CD20. Cytokeratin is also a surface marker that is presented on epithelial cells, is stained histochemically and favors the diagnosis of epithelial tumors like adenocarcinoma. Differentiating poor gastric lymphoma from adenocarcinoma is essential because the prognosis and modalities of treatment differ significantly. Other lymphomas involving the stomach include mantle cell lymphoma and T-cell lymphomas which may be associated with enteropathy; the latter usually occur in the small bowel but have been reported in the stomach. Diagnosis
These lymphomas are difficult to differentiate from gastric adenocarcinoma.