Dengue Fever: A repeat infection is more dangerous than the first

Dengue Fever: A repeat infection is more dangerous than the first

HIGHLIGHTS:

  • There are 4 strains of the dengue fever virus. The body is only able to build immunity to the strain(s) it has previously been exposed to, meaning that one person is capable of contracting all 4 strains of the virus throughout their life.
  • Risks posed by repeat dengue fever infections are much greater than those posed by the initial illness.
  • A dengue fever vaccination can reduce the likelihood of suffering a serious infection by up to 84%, decrease the chances of requiring a hospital stay by up to 79%, and offer up to 82% protection against all 4 forms of the virus.

Dengue Fever: A Silent Scourge Among City Dwellers

The main factor behind dengue fever outbreaks, which extend and accelerate the spread of the virus, is the increase in populations, especially with regard to urbanization. With the increase in places capable of housing standing water among urban communities, in addition to improved travel links domestically and internationally, it is impossible for humans to escape mosquitoes and therefore the scourge of dengue fever despite being healthier than ever before and living in cleaner environments than at any time throughout history.

Additionally, the Covid-19 pandemic has led to us spending more time at home, which is yet another factor at play in dengue outbreaks and increased infection rates.

Aedes Mosquitoes: deadly residents in our homes

There are two types of Aedes mosquito capable of carrying the dengue virus:

1. Aedes aegypti are generally found in and around the home, laying their eggs in still, standing water. This type of mosquito is the most common carrier of disease in urban areas and plays a major role in disease outbreaks.

2. Aedes albopictus are more prevalent in rural areas as they lay their eggs in trees, on leaves and in tree stumps that contain pools of water.

Both types of Aedes mosquito lay their eggs in clean, standing pools of water; they are not generally found in and around wastewater pipes. These mosquitoes bite people during the day, with the following two periods being peak feeding times: 09:00–11:00 and 13:00–15:00.

One Person Can Contract Dengue Fever up to 4 Times?

Most people mistakenly believe that dengue fever has just one strain. However, the truth is that there are 4 distinct strains of this dangerous virus. Once a person has been infected with one strain, their body will build up an immunity to only that strain of the virus. This means that a person can become infected with dengue fever another 3 times in their life. Moreover, each dengue fever reinfection is much more dangerous than the previous infection.

Most Affected Age Groups

Data from the Department of Disease Control for the years 2015–2019 showed the most affected age group for dengue fever infections was 15–44 years, followed by infants aged between 10–14 years.

Dengue Fever Incidences in Thailand

Studies have found that more than 80% of the population over the age of 9 years have been infected with dengue fever at some point, and that the rate of infection increases with age.

Serious Dengue Fever Infections

Annually, more than 500,000 people worldwide require hospital admission for a serious dengue fever infection, and 12,500 of those die because of the virus. Children and adults alike who have previously been infected with the dengue virus are at an increased risk of developing a severe dengue illness should they become reinfected. However, those without a previous infection should not misconstrue this to mean that their first infection will be harmless—initial infections are potentially dangerous, too. Furthermore, considering up to 75% of initial dengue fever infections are asymptomatic, it can quite easily be the case that a person’s first symptomatic infection is not actually their body’s first experience with the virus.

How to Find Out if You Have Dengue Fever

A person suffering from a dengue fever infection will notice the following key symptoms:

1. An acute and lasting high fever that maintains

2. Headaches, nausea, vomiting and loss of appetite

3. Redness in the face, with possible appearance of blood spots on the skin and pain in the right-hand side of the ribcage

4. There is usually a cough but not a runny nose, which is what distinguishes dengue from a common cold, although it is possible to suffer from both conditions at the same time

Those suspecting a dengue infection are advised to seek medical attention immediately. If it is the dengue virus, the fever will normally go away after three or four days of infection. When symptoms include lethargy and loss of appetite for both water and food, medical treatment should be sought straight away. Cases requiring medication should only use paracetamol, as aspirin or other NSAIDs, such as ibuprofen, can lead to internal bleeding. Bland foods are recommended during the treatment stage, and blood-colored foods such as watermelon should be avoided (they can make it difficult to distinguish whether a person is vomiting blood).

Protecting Yourself Against Dengue Fever

There are no specific forms of treatment for dengue fever but there are ways in which we can reduce our risk of contracting the virus:

1. Protect yourself from mosquito bites and limit their breeding grounds

All mosquitoes, including those carrying the dengue virus, tend to bite on the ankles and elbows without the person’s knowledge. Therefore, wherever you are, you should take precautions against mosquito bites by using repellent, as well as limiting the opportunity for mosquitoes to breed at home or in pools of water. This is the simplest, cheapest and most effective way of preventing the virus. This involves closing doors, removing standing water sources in plants, and generally removing any standing water from in and around the home. People can also release fish into ponds as they eat mosquito larvae, while certain chemicals can do a similar job if replacing or pouring water away is not possible.

2. Vaccinate yourself against dengue fever

In addition to maintaining cleanliness in the home to eliminate mosquitoes, consulting an expert physician regarding a dengue fever vaccination can also provide the necessary protection.

The Dengue Fever Vaccination

Currently, dengue fever vaccinations come in the form of a live-attenuated vaccine that offers protection against all 4 forms of the virus. Side effects associated with the vaccine are minimal when compared to other similar vaccines, with pain, swelling and redness at the injection site the most common symptoms. However, some patients may also experience a low fever and rash at the vaccination site, both of which go away after a short time.

This vaccine can reduce a person’s risk of developing a serious dengue infection by up to 84%, while decreasing their chances of requiring a hospital stay by 79% and providing 82% protection against developing a symptomatic illness for all 4 strains of the virus in those who have previously had the disease. Furthermore, the World Health Organization (WHO) recommends that the dengue fever vaccination be widely administered in countries susceptible to dengue fever outbreaks such as those in Asia, including Thailand.

The 3-time course of dengue fever vaccinations (0, 6 and 12 months) is recommended for use among those aged between 9–45 years, as well as in those who have previously contracted the virus.

Who is advised to receive the dengue fever vaccine?

  • Infants with a history of the disease are advised to receive the vaccine. • Infants with no history or no known history of the disease should undergo blood testing prior to making a decision about vaccinating. Although blood tests may not be entirely accurate, they can help to confirm such a decision.
  • Infants who have begun a course of vaccinations that were not completed may consider continuing or halting the course; after discussion with specialist.
  • Adults (under 45) may consider a vaccine without the need for a blood test because there are various studies concluding that over 90% of adults in Thailand have contracted the virus at some point in their lives. However, when possible, a blood test should be considered before a vaccine is administered.

There is a need to communicate to potential recipients that this vaccination does not offer complete protection against dengue fever and, despite receiving the full 3-time course of injections, there is still a chance that a person can contract the disease. There are several ways people can prevent contracting a dengue fever infection, including reducing the likelihood of getting bitten by a mosquito, limiting their breeding grounds, and receiving the dengue vaccine. If someone has symptoms associated with dengue fever, they should seek urgent medical attention whether or not they have been vaccinated against the disease.

References
  1. Hadinegoro et. al. N Engl J Med 2015; 373:1195-1206 Available at: https://www.nejm.org/doi/full/10.1056/nejmoa1506223. Accessed September 2020. 2.
  2. World Health Organization. Dengue and severe dengue. Fact sheet N°117. Updated May 2015. Available at: http://www.who.int/mediacentre/factsheets/fs117/en/. Accessed September 2016.
  3. Sridhar et. al. N Engl J Med 2018; 379:327-340 Available at: https://www.nejm.org/doi/full/10.1056/nejmoa1800820. Accessed September 2020.
  4. Diseases transmitted by mosquitoes. Center for infectious diseases spread by insects, Department for Disease Control, Ministry of Public Health. Dengue Fever. 2019. (Data from the disease monitoring program carried out by the Bureau of Epidemiology, January 3, 2020) Available at: https://ddc.moph.go.th/thaivbd. Accessed January 2020.
  5. Academic manual on dengue fever in the field of medicine and public health. Center for infectious diseases spread by insects, Department for Disease Control, Ministry of Public Health, 2015.
  6. Practical guidelines and recommendations in relation to the dengue fever vaccine. Pediatric infectious disease society of Thailand and the infectious disease society of Thailand. August 1, 2018.
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