What are the initial signs of Zika and Dengue?

As the monsoon season knocks our door, the risk of mosquito-borne diseases also remains high. Diseases such as Zika virus and Dengue pose a significant health risk in tropical regions where stagnant water and hot temperatures provide an ideal breeding ground for mosquitoes. Understanding their distribution, symptoms and potential complications is crucial during this period.
Here's a detailed look at the Zika and Dengue viruses, their stages of disease and precautions to prevent their spread.
Zika virus is an infection which primarily spreads through bites from infected Aedes mosquitoes. This mosquito mostly bites during the daytime. This virus can also be transmitted through sexual contact, blood transfusions and laboratory exposure. A pregnant woman can also pass the virus to her fetus during pregnancy or around the time of birth.
The initial symptoms of the Zika virus are generally mild and can include:
Symptoms typically appear 3 to 14 days after being bitten by an infected mosquito and usually last for several days to a week. Many people infected with Zika virus do not experience symptoms or have only mild symptoms. In some cases, fever with a rash can be the first symptom. Others may experience headache, joint pain, and redness in the eyes. Very rarely, the Zika virus can affect the brain and nerves, potentially causing paralysis and difficulty in walking.

Dengue is primarily transmitted through the bite of an infected Aedes species mosquito, particularly Aedes aegypti and Aedes albopictus. These mosquitoes become infected when they bite a person already infected with the dengue virus. Once infected, the mosquito can spread the virus to other people through its bites.
Incubation Period
Symptoms typically appear 4 to 7 days after a mosquito bite and can last 3 to 10 days.
Phases of Dengue infection
Phase 1 - Febrile Phase:
High fever persists for 2-3 days.
Symptoms include facial flushing, skin redness, muscle and joint pains, headache, sore throat, red eyes, loss of appetite, nausea, and vomiting.
Phase 2 - Critical Phase:
Temperature begins to decrease (days 3-7).
Increased capillary permeability leads to a rapid decline in platelet count and elevated hematocrit levels.
Bleeding manifestations such as gum bleeding or internal organ bleeding may occur.
Without treatment, cases can progress to shock, organ dysfunction, disseminated intravascular coagulation, or hemorrhage.
Phase 3 - Recovery Phase:
Gradual reabsorption of excess fluid from tissues over 2 to 3 days.
Decreased heart rate and overall improvement in health.
(Author: Dr Malathi Murugesan MD DTM&H, Associate Consultant, Department of Infectious Diseases, Meenakshi Mission Hospital and Research Centre, Madurai)