Dengue: Its Types, Transmission, Symptoms and Preventive Measures at Home

Dengue is a mosquito-borne and pandemic-prone viral infection prevalent in many parts of the world. It is a flu-like illness spread by the bite of an 80s mosquito infected with the dengue virus. The 80s mosquito can breed even in a small amount of water accumulated in any container-like object. 

Virus

Dengue is caused by a virus belonging to the Flaviviridae family of which there are 4 distinct serotypes: DENV 1, DENV 2, DENV 3, and DENV 4. It is important to have knowledge of these serotypes because recovery from a dengue infection will provide lifelong immunity against that serotype only. Subsequent infections from other serotypes will increase the risk of developing severe disease.

Transmission

The virus is spread via the bite of a mosquito, mostly by Aedesaegypti and to a lesser extent, by Aedes albopictus mosquito. Important to note here is the fact that these very same mosquitoes are involved in the spread of other viral diseases, including Chikungunya and Zika. The mosquito can become infectious when it bites an infected individual. It then carries the Dengue virus and injects them into another individual during its next meal. Dengue doesn't spread directly from one patient to the next. These mosquitoes can typically be found laying eggs near standing water in containers that hold water like buckets, bowls, animal dishes etc. The incubation period of Dengue is 4-10 days once the mosquito has bitten the individual.

Symptoms

Dengue can cause a wide range of symptoms in a patient, from a subclinical disease in which the patient might be unaware of the infection to a severe infection in which the patient exhibits severe flu-like symptoms.

The symptoms of Dengue include:

1.    High-grade fever around 40°C or 104F, along with 
2. nausea
3.   Vomiting, which is generally non-bilious  Rash
4.   Aches and pains typically involving the area behind the eye which is termed retro-orbital pain
5.   Severe headache
6.   Generalized muscle pain and joint pains.
7. In case of a mild encounter, the patient will recover in about a week. In some cases, however, symptoms can worsen and become life-threatening.

Blood vessels become affected adversely and eventually get leaky. The clot-forming platelets in the blood decrease in number which leads to increased susceptibility of the patient to bleed. This condition is known as Severe Dengue or Dengue Hemorrhagic Fever. This is characterized by;

1. Severe abdominal pain
2. Persistent vomiting, at least 3 times in 24 hours
3. Bleeding from the patient's nose, called epistaxis
4. Bleeding from gums
5. Bleeding under the skin which appears like purplish bruises
6. Feeling tired and restless
7. Blood in urine, also known as hematuria
8. Blood observed in stool and vomit 
9. And eventually, the patient can slip into shock, they may have cold, clammy skin, tachycardia, and hypotension.

Risk factors

Factors like living in or traveling to tropical areas can increase one’s risk of exposure to this virus. The more high-risk areas include Southeast Asia, the western Pacific islands, Latin America, and the Caribbean. Prior infection with a Dengue fever virus can also result in a severe episode of disease if infected again, with a high probability of developing Dengue Hemorrhagic Fever.

Investigation

1) NS1 detection

NS1 is a protein produced by the cells that are infected by the DENV.

2) Enzyme-Linked Immunosorbent Assays or ELISA

It detects the antibodies that are produced by our body to fight viruses.

Treatment and Prevention

The specific treatment for dengue fever is not available yet, but there are several general treatments that can be introduced to patients such as antipyretics to reduce fever and painkillers to treat muscle or joint pain. However, NSAID or non-steroidal anti-inflammatory drugs, like ibuprofen and aspirin should be avoided. They thin the blood and can exacerbate the prognosis of disease with hemorrhage risk. For severe dengue, intensive medical care by physicians and nurses can decrease the progression of the disease and the mortality rates from more than 20% to less than 1%. The management of the patient's body fluid volume is critical to severe dengue care.

Vaccination against dengue

The first dengue vaccine, Dengvaxia, or CYD-TDV, was licensed in December 2015 and now has been approved by regulatory authorities in around 18 – 20 countries. The use of the vaccine is targeted at populations living in endemic areas, ranging from 9 to 45 years of age, who have had at least 1 documented dengue virus infection previously. The vaccine is given in three doses over the course of 12 months. But its efficacy is a matter of debate. The vaccine is only approved for older children because two years after being vaccinated, the younger ones appear to be at increased risk of severe dengue fever and hospitalization. The World Health Organization, WHO, stresses that the vaccine is not the most effective tool.

10 Preventive Measures to be Taken at Home to Prevent Dengue

A more important matter than treatment and vaccines is controlling the mosquito population and human exposure. So, to avoid getting Dengue, our best shot is to avoid getting bitten by mosquitoes carrying Dengue. It is as simple as that. If you are a resident of or traveler to any tropical area where Dengue fever is previously reported, prevention can reduce your risk of acquiring it, which includes:

1. Stay in air-conditioned or well-screened housing because the mosquitoes that carry the dengue viruses are relatively more active from dawn to dusk.
2. Wear protective clothing like a long-sleeved shirt, long pants, socks, and shoes.
3. Use mosquito repellents, like Permethrin to be applied to your clothing, shoes, camping gear, and bed netting.
4. And most importantly, reduce mosquito habitat. You can lower mosquito populations by eliminating habitats where they lay their eggs at least once a week, and emptying and cleaning containers that hold standing water, such as planting containers, animal dishes, and flower vases.
5.  Keep standing water containers covered between cleanings.
6. Drain out and scrub clean garden fountains bird baths and flowerpot baseplates at least once a week.
7. Turn over or cover objects that can collect water such as wheelbarrows drums or bowls Cover overhead water tanks with a tight lid to prevent mosquitoes from entering.
8. Cover the overflow pipes of water tanks with a material that allows water to flow out but prevents mosquitoes from entering clean roof gutters by ensuring the outlet remains open and water does not stagnate in Shore bottles plastic containers or any other discarded material in which water can collect are properly disposed of or recycled at least once a week.
9. Drain out and scrub clean trays under refrigerators air conditioners water cooler tanks indoor flower pots and vases while spraying insecticides to kill mosquitoes focus on dark areas such as closets underneath beds and behind curtains.
10. Leave the doors and windows of your house open when local authorities are carrying out fogging.