World Health Day

Vector-borne Disease Fact Files

Contents

Malaria

Junior……………………………………………………………………………………………1

Senior……………………………………………………………………………………….....2

Dengue Fever

Junior……………………………………………………………………………………………3

Senior………………………………………………………………………………………..…4

Chikungunya

Junior………………………………………………………………………….……………...5

Senior………………………………………………….………………………………………6

Lyme disease

Junior…………………………………………………………………………………………7

Senior…………………………………………………………………………………………8

Junior Disease Fact File- Malaria

Malaria is caused by a type of parasite called a Plasmodium. A parasite is a micro-organism that lives in or on another organism, called a host. Parasites get their food from their host.

Parasites can cause disease in humans. Plasmodium parasites are spread by a particular type of mosquito that bites humans in the early mornings or early evenings. Mosquitoes are commonly found in tropical climates and especially near standing water.

The malaria parasite has a very complex life-cycle. It lives in the mosquito first and then is passed to humans when the mosquito bites and feeds on the human. The malaria parasite mainly lives in the liver and blood of its human host, but can affect other parts of the body including the brain. People with malaria often experience flu-like symptoms, such as fever, chills, headaches and sickness. Malaria can be treated with antimalarial medicine. Plasmodium falciparum, which is found in Africa, is the most dangerous of the malaria parasites. There is no vaccine against malaria.

Malaria infects over 1500 returning travellers to the UK every year. If you are going on holiday to a place where malaria is found, the best way to avoid being infected is to prevent mosquito bites by using insect repellent, covering your arms and legs or by using mosquito nets.

In some cases your doctor can also prescribe you anti-malaria tablets which you need to take before, during and after your holiday. These tablets will kill any malaria parasites in your blood.

Electron micrograph of a Plasmodium parasite migrating through the cytoplasm of a mosquito midgut epithelial cell. Image from Wikimedia

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Plasmodium parasite

Senior Disease Fact File – Malaria

What is malaria?

Malaria is caused by a parasite, Plasmodium spp. A parasite is an organism that lives on or in a host and gets its food from its host. Plasmodium parasites are transmitted by Anopheles mosquitoes when they bite. Approximately 3.3 billion

people live in areas at risk of malaria, however most cases occur in African regions. Malaria is one of the most serious and widespread parasitic diseases in the world. In 2012, 207 million cases of malaria occurred worldwide. Malaria infects over 1500 returning travellers to the UK every year.

What are the symptoms?

People with malaria often experience flu-like symptoms. If left untreated the infected person may develop severe complications and die. Malaria patients show a combination of symptoms such as fever, chills, sweats, headaches, sickness and body aches. These symptoms usually begin 8-25 days after being bitten by an infected mosquito.

Who can get it? People who live in or travel to regions where both malaria and certain Anopheles mosquitoes are present are at risk of being bitten by an infected mosquito. Mosquitoes are commonly found in tropical and sub-tropical climates and especially near standing water. How is it spread?

The Plasmodium parasite is spread by a female Anopheles mosquito. The mosquitoes usually bite people at dawn and dusk. The malaria parasite has a very complex life-cycle. It lives in the mosquito first and then is transmitted to humans when the mosquito feeds on the human. The malaria parasite then lives in the liver and blood, but can affect other parts of the body including the brain. When the parasite is in the blood it causes high fever and breaks down our blood cells causing anaemia and tiredness. How can you avoid catching it?

It is important to be aware of the risk of malaria in the country you are planning on travelling to. If malaria is present in the country you are visiting you should always take anti-malarial tablets, even if the local inhabitants do not take them. It is especially important to take the full course of the malaria prevention tablets, which can be for 4 weeks after you come back from the country. Whilst in the country, try to avoid being bitten by using insect repellent, covering your arms and legs, and by using mosquito nets.

Is there any treatment? Malaria is diagnosed using a blood test. An infected person needs to be treated urgently using anti-malarial tablets. Different anti-malarials are needed for different countries, as some Plasmodium parasites have developed resistance. There is no vaccine to prevent malaria. Photo credit Electron micrograph of a Plasmodium parasite migrating through the cytoplasm of midgut epithelial cell. Image from Wikimedia

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Plasmodium parasite.

Junior Disease Fact File - Dengue Fever

What is dengue fever?

Dengue fever, also called “tropical flu”, is caused by the dengue virus and it is spread to people by mosquito bites from Aedes mosquitoes found in tropical and subtropical countries. Recently the Aedes albopictus mosquito (also called the Tiger mosquito) has appeared in Southern Europe. The number of cases of dengue has increased dramatically around the world in recent years. Symptoms of the disease include flu-like symptoms such as fever, joint and muscle pain and headache. Most people will recover within a few days or weeks. There are currently no medicines to treat dengue fever. People are given medicine to help relieve their symptoms. There is currently no vaccine to prevent the disease. If you are going on holiday to a place where Aedes mosquitoes live, the best way to avoid this virus is to avoid mosquito bites. You can do that by wearing loose, light-coloured clothes that cover your skin and use insect repellent. Mosquito nets can help prevent being bitten whilst sleeping. If possible, use air conditioning since mosquitoes don’t like cold places.

The Aedes mosquito lives and develops close to humans in gardens and houses, and bites during the day-time. Standing water is needed for mosquitoes to lay their eggs in and to allow the eggs to develop into adults. Standing water can collect in tyres, flower pots, watering cans, paddling pools, drain pipes, and any other open containers. By reducing standing water, the mosquitoes will have fewer places to lay their eggs. This can be done by changing, emptying or covering standing water.

Photo Credit

Image from Wikipedia Commons/Giantmicrobes

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Senior Disease Fact File Dengue Fever

What is a Dengue fever?

Dengue Fever (also known as break bone fever or tropical flu) is a viral disease caused by the Dengue virus and spread by the daytime-biting, female Aedes spp (Aedes albopictus and Aedes aegypti) mosquitoes. It is endemic (constantly present) in approximately 100 tropical and subtropical countries, threatening about 40% (2.5 billion) of the world's population. WHO estimates there are around 50 million cases every year. Recently the Aedes albopictus mosquito has also appeared in Southern Europe. What are the symptoms?

Dengue fever causes flu-like symptoms such as fever, severe joint and muscle pain, headache, nausea and vomiting. The symptoms of Dengue fever are similar to those of Chikungunya. Most people will recover within a few days or weeks. The symptoms appear 2-7 days after being bitten by an infected mosquito. In certain circumstances, the disease may progress to Dengue Haemorrhagic Fever (DHF) or Dengue Shock Syndrome (DSS), both of which can be fatal.

Who can get it?

Anyone going on holiday or living in an area where infected Aedes mosquitoes are found.

How does it spread?

The virus is spread from person to person via bites from female Aedes mosquitoes. Mosquitoes become infected when they feed on a person infected with dengue virus.

How can you avoid catching it?

Dengue fever cannot be prevented by vaccination. If you are going on holiday, or if you live in an area where Aedes mosquitoes are present, the best way to avoid this virus is to avoid mosquito bites. You can do that by wearing loose, light-coloured clothes that cover your skin and use insect repellent. Mosquito nets can help prevent being bitten whilst sleeping. If possible, use air conditioning since mosquitoes don’t like cold places

This mosquito lives and develops close to humans in gardens and houses, and bites during the day-time. Small quantities of standing water are needed for mosquitoes to lay eggs in and to allow the eggs to develop into adults. Standing water can collect in tyres, flower pots, watering cans, paddling pools, drain pipes, and any other open containers. By reducing standing water, the mosquitoes will have fewer places to lay their eggs and reproduce. This can be done by changing, emptying or covering standing water. Is there any treatment?

There are currently no medicines to treat dengue fever. People are given medicine to help their symptoms.

Photo Credit

Image from Wikipedia Commons.

Junior Disease Fact File – Chikungunya

What is Chikungunya?

Chikungunya is a disease caused by the chikungunya virus and spread by mosquitoes. It is found in Africa, Asia and more recently Southern Europe and the Americas.

The disease is spread when a particular type of mosquito (known as the “tiger mosquito”) bites humans. This mosquito lives close to humans in gardens and houses and bites during the day-time. Standing water is needed for mosquitos to lay eggs in and to allow the eggs to develop into adults. Standing water can collect in tires, flower pots, watering cans, paddling pools, drain pipes, and any other open containers. By reducing standing water, the mosquitos will have fewer places to lay their eggs. This can be done by changing, emptying or covering standing water or by replacing water in flower vases with wet sand. Symptoms of the disease include fever, joint pain, headaches, muscle pain and a rash. Most people will recover within a few days or weeks. There are currently no medicines to treat chikungunya and there is no vaccine to prevent the disease. People are given medicine to help their symptoms. If you are going on holiday, or you live in an area where mosquitoes are found, try and avoid being bitten by wearing clothes that cover your skin and use insect repellent. Mosquito nets that cover you and the bed can help prevent being bitten whist sleeping.

The Aedes aegypti mosquito feeding on human blood - Image 9257 from CDC’s PHIL

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The Aedes aegypti mosquito is one of the vectors for Chikungunya.

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Senior Disease Fact File – Chikungunya

What is Chikungunya?

Chikungunya is a disease caused by the chikungunya virus which is spread by female mosquitoes (Aedes spp). It is found in many areas of Africa, Asia and more recently in Southern Europe and the Americas. This mosquito lives close to humans in gardens and houses and bites during the day-time. The symptoms of chikungunya are similar to those of dengue fever; therefore chikungunya is sometimes misdiagnosed in areas with high rates of dengue fever. Since 2005, there have been over 1.9 million cases of chikungunya in Asia alone.

What are the symptoms?

Symptoms of chikungunya include the sudden onset of high fever, severe joint pain (mainly in the arms and legs), headache, muscle pain, back pain and a rash in approximately 50% of cases. The symptoms usually appear between 3-7 days after being bitten by an infected mosquito. People recover within a few days or weeks, this may vary depending on age, with the very young and old being more severely affected. Who can get it?

Anyone travelling to areas where Aedes aegypti and Aedes albopictus mosquitoes are present.

How is it spread?

The virus is spread by female Aedes mosquitoes. Mosquitoes become infected when they feed on a person infected with chikungunya virus. Infected mosquitoes can then spread the virus to other humans when they bite.

Aedes aegypti Aedes albopictus

How can you avoid catching it?

If you are going on holiday, or if you live in areas where mosquitoes are found, try and avoid being bitten by wearing clothes that prevent skin exposure and use insect repellent. Mosquito nets can help prevent being bitten whilst sleeping. Standing water is needed for mosquitoes to lay eggs in and to allow the eggs to develop into adults. Standing water can collect in tires, flower pots, watering cans, paddling pools, drain pipes, and any other open containers. By reducing standing water, the mosquitoes will have fewer places to lay their eggs and reproduce. This can be done by changing, emptying or covering standing water or by replacing water in flower vases with wet sand. Is there any treatment?

There is currently no vaccine to prevent chikungunya or any specific medicines to cure the disease. Treatment is based on relieving the symptoms. Photo credit The Aedes aegypti mosquito feeding on human blood - Image 9257 from CDC’s PHIL The Aedes albopictus mosquito feeding on human blood - Image 2165 from CDC’s PHIL

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Junior Disease Fact File Lyme disease

What is Lyme disease?

Lyme disease is caused by the bacterium Borrelia burgdorferi. Ticks can pick up the bacteria when they bite small animals like rodents. The bacteria are then spread to humans when they are bitten by infected ticks, found on high grass or bushes. Ticks are blood sucking members of the spider family. We have about 20 species in the UK. Lyme disease is now the most common vector borne disease in the Northern hemisphere.Ticks are becoming more common across large parts of England, particularly in woodlands, along woodland edges, on heathland and moorland and in some grassland sites.

The first symptom of the disease is a rash around the bite which will extend. The infection can be cured with an antibiotic treatment, but the earlier the treatment is started, the better.

There is no vaccine to prevent the disease. Anyone who gets bitten by ticks carrying the bacteria can get Lyme disease. The best way to avoid catching Lyme disease is to avoid being bitten by ticks.

You should wear long, light coloured, trousers and a hat when walking in wooded areas or where there are tall grasses or bushes. After walks or activities check for ticks on your skin. Ask your parents to check your hair, and also check that infected ticks are not brought home on clothes or your pet’s fur. If you find a tick, ask an adult to remove it with a pair of tweezers.

Photo Credit

Borrelia burgdorferi - Used with permission from Giantmicrobes, Inc. www.giantmicrobes.com/uk/

Lyme disease bullseye rash. Image from Wikipedia Commons. Photo credit Hannah Garrison.

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Senior - Lyme disease

What is Lyme disease?

Lyme disease is an infection caused by spiral-shaped bacteria called Borrelia burgdorferi, which are carried by some types of ticks (Ixodid). Ticks can pick up the bacteria when they bite small animals like rodents. The bacteria are then spread to humans when they are bitten by infected ticks, found on high grass or bushes. Ticks are blood sucking members of the spider family. We have about 20 species in the UK. Lyme disease is now the most common vector borne disease in the Northern hemisphere

How do I know I have it: what are the symptoms?

Symptoms normally start with a circular rash spreading from the site of a tick bite 2 or 3 weeks after the bite. General signs such as fever, headache, joint and muscle pain can also be present, although sometimes there are no signs at all. If the infection is not treated more serious problems can occur on the skin, joints (such as arthritis) or nervous system (e.g. facial palsy).

Who can get it?

Anyone who gets bitten by the ticks carrying the bacteria can get Lyme disease. Ticks are particularly present in forests, woodland and heath land. Areas in the UK include many popular holiday and outdoor activity destinations such as the New Forest, Exmoor, other woodland or heathland areas of southern England, the Lake District, the Scottish Highlands and Islands, North York moors, Thetford Forest, the South Downs. Although these are high risk areas for Lyme borreliosis, any area where ticks are present should be regarded as a potential risk area. There were 998 provisional cases of Lyme disease reported to Public Health England in England and Wales in 2012.

Domestic animals can also catch Lyme disease from ticks, but this disease cannot then be transmitted to humans.

How does it spread?

The bacteria are spread from deer or smaller animals such as rodents to humans by infected ticks that can transmit the bacteria when they bite. Ticks are very small (about the size of a poppy seed), and can easily be overlooked, so it is important to be aware of the risk of tick bites.

How can you avoid catching it?

No vaccine against Lyme disease is currently available. The best protection against Lyme disease is to avoid being bitten by ticks.

You should wear long, light coloured clothes when walking in wooded areas or where there are tall grasses or bushes. Insect repellents may also be useful to protect uncovered areas of skin. After walks or activities in tick-infested areas, it is important to check your skin for attached ticks. Carefully check your head and neck and ask an adult to check your hair. Also make sure that pets do not carry ticks home on their fur.

A tick usually has to be attached to the skin for at least 24 hours before it can pass the bacteria to you and so it is important to remove any ticks you find straight away. If you find a tick, ask an adult to remove it with tweezers, pulling steadily away from the skin and then cleaning the bite with soap and water. The bite should be observed for several weeks, and if a rash appears you should consult your GP.

Can it be treated?

All stages of the infection can be treated with antibiotics, but it is easiest to treat at an early stage, especially when the rash is present.

Photo Credit

Borrelia burgdorferi - Used with permission from Giantmicrobes, Inc. www.giantmicrobes.com/uk/ Lyme disease bullseye rash. Image from Wikipedia Commons. Photo credit Hannah Garrison.

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