Hemant Sundas -Health Assistant Officer Government of Nepal
Dengue is a mosquito-borne viral infection or disease caused by four types of viruses (DENV-1, DENV-2, DENV-3, DENV-4) belonging to the Flaviviridae family. Dengue virus is transmitted by female mosquitoes mainly of the species Aedes aegypti. This mosquito also transmits chikungunya, yellow fever, and Zika infection. Dengue is widespread throughout the tropics, with local variations in risk influenced by frequent rainfall, temperature, and unplanned rapid urbanization. Dengue occurs in urban and suburban settings with higher transmission rates happening during the rainy season. These mosquitoes thrive in areas with standing water, including puddles, water tanks, containers, flower vase, fridge water, and old tires, etc. Lack of reliable sanitation and regular garbage collection also contribute to the spread of the mosquitoes.
The Aedes aegypti mosquito is the primary vector of dengue. The virus is transmitted to humans through the bites of infected female mosquitoes. After virus incubation for 4–10 days, an infected mosquito is capable of transmitting the virus for the rest of its life. Infected symptomatic or asymptomatic humans are the main carriers and multipliers of the virus, serving as a source of the virus for uninfected mosquitoes. Patients who are already infected with the dengue virus can transmit the infection (for 4–5 days; maximum 12) via Aedes mosquitoes after their first symptoms appear. The Aedes aegypti mosquito lives in urban habitats and breeds mostly in man-made containers. Unlike other mosquitoes Ae. aegypti is a day-time feeder; its peak biting periods are early in the morning and in the evening before dusk. Female Ae. aegypti bites multiple people during each feeding period. Aedes eggs can remain dry for over a year in their breeding habitat and hatch when in contact with water.
Signs and Symptoms:
Symptoms vary depending on the severity of the disease.
-Mild dengue fever:
Symptoms usually last for 2–7 days, after an incubation
period of 4–10 days after the bite from an infected mosquito.
•aching muscles and joints
•body rash that can disappear and then reap
•high fever (40°C/104°F)
•pain behind the eyes
•vomiting and feeling nauseous
Symptoms usually disappear after a week, and mild dengue rarely involves serious or fatal complications.
-Dengue hemorrhagic fever (DHF):
At first, symptoms of DHF may be mild, but they gradually worsen within a few days. As well as mild dengue symptoms, there may be signs of internal bleeding.
A person with DHF may experience:
•bleeding from the mouth, gums, or nose
•damage to lymph and blood vessels
•internal bleeding, which can lead to black v and feces or stools
•a lower number of platelets in the blood
•sensitive stomach (abdominal pain)
•small blood spots under the skin
Without prompt treatment, DHF can be fatal.
-Dengue shock syndrome (DSS)
DSS is a severe form of dengue. It can be fatal.
Apart from symptoms of mild dengue fever, the person may experience:
•intense stomach pain
•sudden hypotension, or a fast drop in blood pressure
•blood vessels leaking fluid
Without treatment, this can result in death.
Dengue is viral so there is no specific treatment or cure. However, an intervention can help, depending on how severe the disease is.
For milder forms, treatment includes:
•Preventing dehydration: A high fever and vomiting can dehydrate the body. The person should drink clean water, ideally boiled. Rehydration salts can also help replace fluids and minerals.
•Painkillers, such as Paracetamol: These can help to lower fever and ease the pain.
Be careful that Non-steroidal anti-inflammatory drugs (NSAIDs), such as aspirin or ibuprofen, are not advised, as they can increase the risk of internal bleeding.
More severe forms of dengue fever may need:
intravenous (IV) fluid supplementation or the person cannot take fluids by mouth.
Hospitalization will allow the individual to be properly monitored, in case symptoms get worse.
No vaccine can protect against dengue fever. Only avoiding mosquito bites can prevent it.
Anyone who lives in or travels to an at-risk area can use a number of ways to avoid being bitten.
If you are spending time in a tropical region, use mosquito nets that are treated with insecticide.
•Clothing: Reduce the amount of skin exposed by wearing long pants, long-sleeved shirts, and socks, tucking pant legs into shoes or socks.
•Mosquito repellents: Use a repellent with at least 10 percent concentration of diethyltoluamide (DEET), or a higher concentration for longer lengths of exposure. Avoid using DEET on young children.
•Mosquito traps and nets: Nets treated with insecticide are more effective, otherwise the mosquito can bite through the net if the person is standing next to it. The insecticide will kill mosquitoes and other insects, and it will repel insects from entering the room.
•Door and window screens: Structural barriers, such as screens or netting, can keep mosquitos out.
•Avoid scents: Heavily scented soaps and perfumes may attract mosquitos.
•Timing: Try to avoid being outside at dawn, dusk, and early evening.
•Stagnant water: The Aedes mosquito breeds in clean, stagnant water. Checking for and removing stagnant water can help reduce the risk.
Careful clinical detection and management of dengue patients can significantly reduce mortality rates from severe dengue.