In the first article I talked about the best ways to avoid getting bitten by mosquitoes and consequently how to avoid catching some of the many diseases they carry. Here we will look at a few of the most common and well known of those diseases and the consequences of not using your DEET based insect repellents and mossie nets properly.

Malaria

This is the one mosquito borne disease that eclipses all others. With up to 300 million cases of malaria reported each year it kills more people worldwide than any other disease. It is actually caused by a parasite that is injected into an individual along with some of the mosquito saliva, and from this initial point of invasion within minutes heads to the liver and sets up home where it develops over a period 7 days – 1 year. When its ready to leave the liver it may have reproduced into 40,000 parasites all ready to cause fever, illness and possibly death within a few days. Every year about a thousand travellers from the UK will get malaria, unfortunately a handful of who will become seriously ill or die. The initial effects of the disease are very similar to a mild viral infection, headache and general malaise, but it will rapidly move onto severe fever and chills, profuse sweating, diarrhoea, stomach pain and cough. At this point if it is not treated correctly it starts to get nasty. Many people are reluctant to take medications that can prevent malaria because of stories they have read about in the media, or something that happened to a friend of a friend. Those that have had malaria and recovered (which most people do) have described it to me as the worst case of flu that they have ever had and definitely not something that they would want to experience again, these people invariably take their tablets wholeheartedly and come back for more!

Dengue Fever

Whereas malaria is carried by a night time biting mosquito, dengue fever is transmitted by a daytime biting cousin. It is present in Asia, Africa and Central/South America. It frequently causes outbreaks in various countries but a fairly recent outbreak in Brazil was massive and present all along the Eastern coast, it resulted in thousands of cases including professional footballers and plenty of tourists and travellers. In otherwise healthy westerners it is rarely fatal but can be very serious and even the milder cases can be a very unpleasant experience. It is known in many places as ‘breakbone fever' because of the severe pain felt by sufferers, after about 4 days or so you often get a very fine rash followed shortly by a full recovery. If you happen to be a child, elderly, immunocompromised or just unlucky, the disease can move on to what is known as ‘dengue haemorrhagic fever' (DHF for short), this will generally happen if you have had dengue before and been careless enough to get it again. There is no vaccine against dengue fever at the moment although we are hopeful that there will be a good vaccine on the market very shortly. It is therefore important for an individual to reduce the number of mosquito bites received during the day as well as during the evening.

Note: Insect repellents should always be applied after sunscreens, and it's worth bearing in mind that DEET based insect repellents may reduce the effectiveness of your sunscreen.

Yellow Fever

This virus is carried by another type of daytime biting mosquito and is present across all of Sub Saharan Africa and a majority of South America. It is not currently found in any parts of Asia though the conditions are right, and therefore all Asian countries are doing their best to prevent its introduction. Unlike malaria, it is found in even the largest urban populations and apart from bite avoidance the best way to prevent catching yellow fever is to have the vaccine before exposure. The vaccine takes 10 days to become fully effective, but following this short period virtually 100% cover is achieved. When you are vaccinated you are given a little certificate that becomes your ‘yellow fever passport'. It is the presentation of this document that allows travel across borders in Africa, South America or travel to an area such as Asia when travelling from an infected country. The disease manifests itself initially as fever and jaundice (hence yellow fever), but again can move on to become haemorrhagic yellow fever for which there is no specific treatment except fluids to treat the shock and internal blood loss. Yellow fever can be fatal in almost 50% of non-vaccinated individuals during an outbreak, so that vaccine is well worth getting.

Japanese B Encephalitis

Although very rare amongst travellers it a potentially very serious disease present throughout Asia, although it occurs only very, very rarely in Japan. It is caused by a virus spread via the bite of an infected night time biting mosquito that breeds mainly in paddy fields. The most commonly infected animals are pigs and fowl – wading birds etc so in order to be in an area of risk you need paddy fields just around the corner and pigs at your feet. Actually quite a common sight in Asia but it also tends to have seasonal outbreaks especially at the end of the rainy season, for example around May in the southern areas of Nepal. If you think that you may be in these risk areas at high risk times there is a vaccination course available of two or three shots but you really should start this course a minimum of 38-40 days prior to travel.

For more information, visit the Nomad Travel web site: Nomad Travel or call the Travel Health Line: 0906 8633414 (calls cost 60p per min) to discuss your travel health queries with a medical.