Dengue Fever – a Short Overview

The virus can affect infants, young children and adults; in rare cases the disease is lethal. With 285–528 million people infected annually, Dengue fever is the most common mosquitotransmitted disease in the world. The virus is transported from one region to another by infected travelers.

In which parts of the world does Dengue Fever most often occur? Dengue is mostly found in tropical and sub-tropical climates, worldwide. Predominantly, people suffer from Dengue in South-East Asia, Africa and the Caribbean, but also in Australia and Hawaii; some epidemics have occurred in South-America and India. Local variations in risk are influenced by temperature, rainfall and unplanned, rapid urbanization .

How does Dengue get transmitted ? Dengue is a mosquito-borne viral infection. The virus is transmitted through the bite of an infected female yellow fever mosquito Aedes aegypti. This species is the most important vector, in rare cases Aedes albopictus carries the virus. Aedes aegypti also transmits Zika, Chikungunya and Yellow fever. Because the mosquito sucks blood from both infected symptomatic and asymptomatic humans, it is the major multiplier of the virus. Infected people transmit the infection to the mosquitoes after their first symptoms appear .

How does the virus develop in humans? Aedes aegypti lives in urban habitats and its larvae develop (mostly) in man-made , water-filled containers. As a day-time feeder , its biting and activity time is early in the morning and in the early evening, before twilight . Female mosquitoes bite multiple people during each feeding period. The eggs can remain dry for over a year in their breeding habitat and the larvae can develop if they get water contact (usually after tropical rainfall). After biting a human, the virus leaves the infectious mosquito through saliva . Via the lymphnodes, the virus enters the human reticulo-endothelial system. Here, the virus reproduces. This is the viremic phase (1st–4th day of fever). During this phase of the disease, the mosquitoes infect themselves with the virus when they suck blood from an infected human and will then transmit the virus for the rest of their life (2–4 months).

What symptoms do Dengue patients develop? After an incubation period of about 2–8 days, dengue patients suffer from severe , flu-like symptons: they develop a high fever (40° C) accompanied by severe headaches, ague , pain behind the eyes (lightsensitivity), muscle and joint pain, nausea , vomiting , swollen glands and/or rashes. Symptoms can last 2–7 days. The infection can also be asymptomatic.

How to distinguish Dengue infection from severe Dengue? A deadly complication to dengue is severe dengue. Compared to dengue, you notice a decreasing fever (below 38° C) and severe persistent vomiting (sometimes with blood), abdominal pain, rapid breathing, bleeding gums, fatigue and restlessness . If such symptoms are observed, the next 24–48 hours can be lethal and the patients need rapid, expert medical care.

What about laboratory diagnostics? The dengue virus is a member of the RNA-carrying family of Flaviviridae, part of the large group of arboviruses. Four serotypes exist: DEN-1, DEN-2, DEN-3 and DEN-4. This means that each human can potentially get dengue four times. Infection recovery from one particular serotype provides the humans with lifelong immunity to this particular serotype, but not to any other serotype. Cross-immunity is only temporary. Secondary infections with other serotypes significantly increase the risk of developing severe dengue.

Is there any immunization or treatment available? Yes, there is a vaccine on the market. Dengvaxia® (CYD-TDV) is the first vaccine (licensed in December 2015). It is now allowed and introduced in 19 countries in the endemic areas. For seronegative people, the risk is higher to develop more severe dengue and hospitalizations from dengue compared to unvaccinated people. The vaccine CYD-TDV is active in people who are seropositive (i. e. had a previous dengue virus infection). Only people with antibodies against Dengue virus can be pre-vaccinated. A new vaccine is undergoing clinical trials and could be introduced in Europe in 2020. People (vaccinated or not) should get prompt medical care if dengue-like symptoms occur.

EXERCISE: 1. The main Dengue vector is Aedes albopictus. a. True b. False

2. Dengue fever can be lethal.

a. True b. False

3. There are six serotypes/genotypes for Dengue.

a. True b. False

You’ll find the answer on: http://tinyurl.com/weiterbildung-englisch

BIBLIOGRAPHY 1. www.auswaertiges-amt.de. 2. www.cdc.gov. 3. www.crm.de. 4. www.dict.cc. 5. http://dict.leo.org. 6. www.rki.de. 7. www.webster-dictionary.org. 8. www.who.int.

CARMEN LOBITZ Carmen Lobitz ist freie Trainerin, Lehrerin und MTA. Sie gründete 1998 in Berlin lobitz seminare, die unter anderem Englischseminare für Health Professionals anbieten. Kontakt: mail@lobitz-seminare.de www.lobitz-seminare.de

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Lösung für Exercise:

Answer: 1. b

Answer: 2. a

Answer: 3. b

Dengue Fever – a Short Overview

In which parts of the world does Dengue Fever most often occur?

How does Dengue get transmitted?

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Dengue Fever – a Short Overview

In which parts of the world does Dengue Fever most often occur?

How does Dengue get transmitted?

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