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Hong Kong has confirmed its 29th local case of Dengue Fever this year, making it the highest number of cases since records began in 1994 when notification was required for every case treated. The last time such a large outbreak was recorded was in 2002, when there were 20 local cases.

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A rash of recent cases

While Hong Kong is no stranger to dengue fever, with over 100 cases of the mosquito-borne disease a year in the last 5 years, the majority of these are imported cases where people have contracted the disease in other countries before returning to Hong Kong. In fact only 1 local case was confirmed in 2017, with 4 cases in 2016 and 2 in 2015.

Hong Kong’s Centre for Health Protection (CHP), the arm of the Department of Health responsible for disease control and prevention, has identified two hotspots as the source of the majority of this year’s cases: Cheung Chau island and Lion Rock Park in Wong Tai Sin.

Government officials made the decision to close Lion Rock Park for 30 days, starting on August 17th to reduce the chance of more infections, as well as to carry out anti-mosquito measures such as removing sources of standing water, use of larvicide and fogging of pesticide to kill adult mosquitoes.

Measures have also begun in Cheung Chau, a popular island for tourists, including disinfecting areas within 500 metres of each patient’s home as well as fogging pesticides near homes and schools on the island.

Dengue is an issue in Asia and globally

While Hong Kong is having an outbreak of locally-contracted cases of dengue fever in 2018, the risk of infection in the country remains relatively low and usually falls in line with other nearby places such as Macau and Taiwan, which have reported 1 and 33 local cases respectively.

Many countries in South & Southeast Asia have a much greater struggle with Dengue Fever, which is endemic to many countries in the region. One such country is Thailand, where health officials have reported a total of 50,079 cases reported across the 77 provinces so far this year, with 65 people having died from complications of dengue. Other countries in the region, like Vietnam, Sri Lanka and Malaysia have also experienced high numbers of cases.

One problem is that cases of dengue often go unreported, so having a complete view of how many cases there are is a challenge. However, one recent estimate modelled on known cases of dengue indicate that there may be as many as 390 million dengue infections a year, although the model shows that only 96 million show any symptoms.

Dengue fever and its symptoms

Found in tropical and sub-tropical areas around the world, dengue fever is caused by 4 different strains of the dengue virus which is transmitted to humans by Aedes mosquitoes. While the infection is not contagious and cannot be passed between humans, if a patient with dengue is bitten by another mosquito then the mosquito can become infected and able to transmit the disease further.

Dengue can take between 3-14 days to incubate, although its symptoms usually appear between 4-7 days. Symptoms of the disease may include a high fever, muscle and joint pain, headaches, dizziness, rashes and more, however it is important to remember that dengue fever can have widely varying severity for different people.

Some people display minimal symptoms, or even none at all, making treatment difficult as they may not know they’re sick. Researchers believe this may be one of the biggest contributors to the spread of the virus, with mathematical models showing that asymptomatic individuals could be responsible for up to 80% of infections.

Unfortunately, some people can develop severe dengue, also known as dengue haemorrhagic fever, which can lead to additional complications such as bleeding from the nose or gums, bruising, seizures and in more serious cases lead to internal bleeding, circulatory failure, shock and sometimes death.

Signs that a dengue patient may have dengue haemorrhagic fever can include severe abdominal pain, persistent vomiting, a change in mental state or signs of bleeding. Patients who experience any of these symptoms should seek immediate medical assistance to determine if they have severe dengue.

Treatment for dengue

There is no specific treatment for dengue, so for patients with dengue medical efforts are focused on managing symptoms and staying hydrated.

For cases of severe dengue, medical treatment can be essential as it can reduce the mortality rate from 20% to less than 1%. Patients with severe cases may require IV fluids for hydration, blood transfusions and other monitoring of their vital signs.

For pain management, patients with dengue should only use acetaminophen (also known as paracetomol), as aspirin and non-steroidal anti-inflammatory drugs can increase problems associated with bleeding and low blood pressure.

If you have contracted dengue, or believe you may have, continue to use mosquito repellent for 14 days afterwards or until your doctor says you have recovered. This will help prevent mosquitoes from biting you and being able to spread the disease to others.

Preventing mosquito-borne diseases and proliferation

Prevention is the most important part in the fight against dengue, and much of it revolves around trying to limiting the spread of mosquitoes and the possibility of being bitten.

To prevent mosquito-borne diseases, the Hong Kong Centre for Health Protection recommends:

  • Wearing long-sleeved, light-coloured shirts and trousers
  • Applying insect repellent that contains DEET to both exposed skin and clothing per the instructions on the container.
  • Avoid using fragrant cosmetics and skin care products.

In order to prevent the spread of mosquitoes, especially during a rainy season:

  • Make sure to prevent places where water may become stagnant. This may include:
    • checking gutters and drains for blockages
    • changing the water in plants weekly and try to avoid using saucers under plant pots if possible
    • sealing or emptying exposed water containers
  • Clean drains and water surface channels with an alkaline detergent to remove leftover mosquito eggs.
  • Properly dispose of solid waste where water may pool, such as cans and bottles.

Making sure you have access to treatment

When travelling or living in an area where you may be exposed to dengue, make sure that you have access to treatment. This may be especially important for travellers who are spending an extended period of time in a tropical region or country where the disease is endemic.

If you are infected with dengue while on a short trip abroad, you may already be on your way back to your home country before symptoms start to appear, in which case you should be able to use your regular health insurance or national healthcare system to make sure you receive any needed treatment. Be sure to tell your doctor where you travelled to and whether you can remember any contact with mosquitoes on your trip.

If you are on a trip where you would be staying in the country long enough to show symptoms if you contracted dengue, make sure that your travel insurance policy or international health insurance policy will be able to cover any medical expenses. If you are travelling to more remote areas, where accessing quality healthcare would be an issue, you may want to make sure that your plan covers you for any emergency medical evacuations.

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