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By Dr. Spike Briggs
During the past few years, several viral illnesses have become established in South America, the Caribbean and increasingly in North America. The main ones are dengue fever, chikungunya and, more recently, Zika.
There is a common factor here: the mosquito Aedes aegypti.
We are all used to covering up at night to avoid getting bitten by the mosquito Anopheles that spreads malaria, but the problem with Aedes aegypti is that not only is it somewhat active at night, it’s mostly active during the day.
And therein lies the problem. It’s too easy to get bitten during the day by an infected mosquito, and subsequently to contract one of these viral illnesses.
The most important defense — and probably the only defense at present — is to avoid getting bitten. The gold standard to deter mosquitos is the insect repellent DEET (diethyl-meta-toluamide). There are lots of brands of insect repellent on the market containing DEET.
It is not easy to know whether someone has contracted one of these diseases. Each has a spectrum of symptoms that overlap with other viral illnesses and can even be confused with normal flu-like symptoms.
Blood tests can be performed to look for evidence of infection in the blood, but these need to be performed in a clinic or hospital and are not completely reliable.
These three illnesses are usually self-limiting in the majority, and treatment comprises controlling symptoms such as fever, arthralgia (joint pain) and myalgia (muscle pain) using paracetamol (acetaminophen) and maintaining good hydration.
However, all three of these viral illnesses can be associated with short- and longer-term serious complications. A brief profile of each illness is outlined here:
Dengue fever, also known as breakbone fever due to the sometimes severe joint and muscle pain, has no specific cure, although a vaccine is available. It is spread by mosquitos active during the day (Aedes aegypti and other species). It’s range is in the tropics and subtropics, including South America, Caribbean, North America and now southern Europe.
A vaccine was introduced in Mexico in December 2015. Further vaccines are under development by the World Health Organization.
Symptoms usually become apparent from three to 14 days after the infecting bite. They include fever, arthralgia and myalgia, headache, occasional nausea and vomiting, and a rash generalized over most of the body.
Seek medical help, but treatment is usually just supportive (hydration and paracetamol).
Serious complications result in fewer than 5 percent of sufferers but may include haemorrhagic fever.
Chikungunya is another viral illness with no specific cure. Like dengue, it is spread by mosquitos active during the day (Aedes aegypti) and has a range of the tropics and subtropics, including the Caribbean and Central America, now spreading into North America, Europe and the Far East.
Symptoms usually become apparent three to seven days after the infecting bite and, like dengue, include fever, arthralgia and myalgia, headache, occasional nausea and vomiting, and a generalized rash.
Seek medical help, but treatment is usually just supportive (hydration and paracetamol). Serious complications are unusual, but joint pain can be prolonged, possibly leading to a chronic pain syndrome lasting years.
The Zika virus originated in the Zika Forest in Uganda about 60 years ago. Like dengue and chikungunya, it is a viral illness with no specific cure that is spread by mosquitos active during the day (Aedes aegypti). There are also reports of spread by sexual contact.
Its range is in south, central and north America, Caribbean, Samoa and other Pacific Islands, and it is spreading quickly. Several cases have recently been reported in Miami. As a result, the Centers for Disease Control and Prevention has issued a travel advisory for pregnant women and will be advising the state on mosquito testing, management and prevention methods.
Symptoms are usually mild, and become apparent a few days to a week or so after the infecting bite. They include fever, rash that becomes generalized, transient arthralgia and myalgia, and conjunctivitis (red eyes).
The illness is usually mild with symptoms lasting from several days to a week as the virus stays in the blood for a few days (sometimes longer). Severe disease requiring hospitalization is uncommon. Serious complications are possibly the risk of birth defects (microcephaly) and Guillain Barre Syndrome. Further research is being undertaken to establish the links between these two diseases and Zika.
There is no treatment for this virus, and risks are greatest for people of reproductive age.
There are several websites that are regularly updated with the latest verifiable information on these three illnesses and more.
Dr. Spike Briggs is medical director of Medical Support Offshore, a global medical provisioning company. Contact him through Info@msos.org.uk.