Malaria is a disease caused by a parasite from the Plasmodium parasites family, which were probably around since before dinosaurs. It's also called a tropical disease because that's where it mostly affects people and animals. Its symptoms include fever, headache, chills and sweating and it may cause a person to become weak or tired. If left untreated, people can die from malaria complications such as anemia, kidney failure or cerebral malaria.
Malaria is spread when mosquitos breed in the feces of infected animals or the sporozoites (larvae) get into humans through mosquito bites and they then reproduce in red blood cells until there are enough of them to infect a new individual.
In the UK, malaria is rare. But in some parts of the world it is still a major cause of ill health and death. In Africa, there were 214 million cases in 2010 and 660,000 deaths.
Malaria is a disease caused by parasites known as Plasmodium parasites that are spread to humans through the bites of infected mosquitoes. The parasite enters red blood cells to grow and multiply because it needs an environment rich in nutrients and oxygen to survive. When the infected red blood cell bursts it releases new parasites into the body which then spread to other red blood cells. They then go on to cause the symptoms of malaria. The symptoms stay with you for some time.
Malaria is spread by the bites of Anopheles mosquitoes, which are mostly pests in all kinds of places, not only in tropical regions or farm areas. When they see a human in the night they will bite them and lay eggs under their skin (on the lower legs or arms) that when hatched start to feed on the blood of those who have been bitten. However, sometimes a mosquito can carry parasites and not bite anyone else, but still get infected and start causing problems for someone else.
The parasites that cause malaria can enter the human body in a number of different ways. They can live and grow to sexual maturity in a human host, or they can be transmitted directly from one human to another through the placenta during pregnancy, or through blood transfusions. People who have had malaria before are able to pass on their resistance to the disease (to their children, who will then be protected from it themselves). However, this immunity does not last very long; most people's bodies will not resist infection again for more than three years.
Malaria is most often caused by three species of Plasmodium parasites. The symptoms depend on which species of malaria the person has contracted and how much of the parasite there is in their bloodstream. Symptoms can include:
The symptoms go away after a few weeks or months, but they can be followed by a relapsing form of malaria that will cause symptoms again a few months later if an infected person sleeps in a badly-ventilated room and not in bed nets. If these people are not treated well enough, they may die from severe anemia. The main symptom is fever; head pain and chills also occur but are less common (about 15%).
The symptoms of cerebral malaria are similar to those of severe cerebral malaria in children. It can also cause seizures, changes in mental status and coma which can result in death.
Malaria is usually not a fatal disease if diagnosed and treated early on, but it can be dangerous because complications can occur without warning. It is necessary to keep an eye on patients because some people do have a fever for several months after recovery that may cause complications, including relapses (attacks) with subsequent infections. In these cases the patient needs to be isolated from the rest of the population and treated quickly so as not to spread the infection any further.
There are measures that prevent people catching malaria. The best way to avoid mosquito bites is to wear long-sleeved, loose fitting clothing and to use bed nets which can be treated with insecticides or impregnated with permethrine or another pyrethroid compound. There are a number of products available on the market that repel mosquitoes and help protect against malaria such as sprays, gels and lotions. Some types of insect repellent contain DEET (N,N-diethyl-meta-toluamide) which should not be used on children because it is toxic. Insect repellents containing citronella, camphor and rosemary, although not as effective, are also available. It is advisable to use these products in combination with using protective clothing and sleeping under mosquito nets.
Anti-malaria drugs are also available, but they need to be taken as soon as a person develops flu-like symptoms. Chloroquine is the most common drug used to treat malaria. The drug kills the parasite in people's red blood cells by stopping them from being able to use glucose for energy. This means that the parasite will gradually starve and will eventually die without harming an infected person's red blood cells or other parts of their body. This drug is cheap and easily available but can cause dangerous side effects, such as convulsions, hallucinations and confusion which can become permanent. There are also other drugs that are available to treat malaria that are not so dangerous. These include sulphadoxine-pyrimethamine, primaquine and sulfadiazine.
Prevention of relapses is done by giving patients with malaria tablets or taking a daily tablet for several months after the acute condition has run its course. A protective product, called eflornithine hydrochloride, can be used as a skin spray by pregnant women to prevent their babies from being infected too if they drink their amniotic fluid while they were in the womb.
Until the 1960s, malaria was one of the biggest global killers. It is now much less common because it can be prevented by using anti-malarial drugs and other measures discussed above. When a person has fever and symptoms of malaria, they need to see a doctor as soon as possible. Blood tests can confirm if the person has malaria and give information about which type of parasite has caused it. During treatment certain types of people need extra care. For example, pregnant women with severe malarial illness will require blood transfusions for anemia due to their low haemoglobin levels.
The first symptoms of acute malaria are often fever, general malaise and headache. The next few days outbreak into a period of intense fevers. This phase lasts for 3–5 days and the patients become very uncomfortable, having frequent chills, cough and sweating. During this time people may also complain of a sore throat, nausea and vomiting. After a short break the second phase begins with symptoms becoming more distinct again:
This phase lasts for 12–24 hours and the most common symptoms include chills, nausea, vomiting and diarrhoea.
The third and last phase starts with a sudden onset of severe chills lasting for 24 hours, then it continues with the gradual return of the fever, the feeling of shivering, the inability to eat and loss of appetite. About 10–20% of people who have malaria when they are first treated die due to complications during this phase.
During this phase a person may feel extremely unwell and may vomit or pass blood but they usually feel much more stable after an episode of illness than they did before. However, if the person has underlying lung problems such as asthma or cystic fibrosis, then particularly severe symptoms can be prolonged and severe discomforts can occur. For these people it is important to seek medical advice quickly.
When malaria is treated in time, the chance of surviving is very high. About 90% or more of children and adults with malaria will make a full recovery if they are treated early enough. Children who develop severe malaria can recover as well but this will take longer. Between 2 and 5% of all people who recover from a bout of severe malaria become carriers for life. These people are not able to spread the infection to others but can get ill again themselves if they do not take anti-malarial drugs regularly and have been infected by "Plasmodium falciparum" especially if they have not received treatment that has included primaquine.
Malaria is the only parasitic disease that affects all human beings in all parts of the world. It is a life-threatening disease which can lead to death if left untreated. In order to prevent children dying from malaria, it is important that they are given anti-malarial drugs and other measures discussed above as soon as they start to feel ill.
Insecticide resistance is an increasing problem and even harmless insect repellent can cause problems because some insects are developing resistance to certain chemicals. The best way of avoiding insect bites is to wear long-sleeved, loose fitting clothing and to use protective mosquito nets during the night when mosquitoes are most active.
Malaria is far less common in high-income countries, but it affects people of all ages and areas of the world. It is an important public health problem for countries that are not as well-developed as countries like Australia and New Zealand. Malaria kills close to half a million people every year and causes a lot of economic problems for its host countries. For example, this disease caused about 7% of deaths in Zambia in 1997 and a similar number to Guatemala in 1999. In 2000 it caused at least 1 million deaths worldwide.
There are about 1,500 different species of mosquito. They can be found all over the world with the exception of Antarctica and some islands. The main species that spread malaria are Anopheles gambiae ("Plasmodium falciparum"), Anopheles funestus ("Plasmodium vivax"), Anopheles darlingi ("Plasmodium ovale") and Anopheles minimus ("Plasmodium malariae"). These mosquitoes usually breed in stagnant or slow-moving fresh water such as lakes, pools, ditches and puddles in and around houses. However, they will move to other sources of water if these become available nearby.
Mosquitoes can carry not only malaria but also other diseases such as filariasis and dengue fever. However they do not spread the disease and they can only transmit the next stage of the parasite to people and animals through the bite.
There are a number of different strategies which have been put in place to reduce the impact of malaria on poor countries. These strategies include reducing agricultural workers, improving sanitation and mosquito control, controlling outbreaks, reducing drug resistance and increasing access to anti-malarial drugs. There is also a complex combination of measures that must be taken in order to minimise resistance in mosquitoes.
The issues in stopping drug resistance in malaria infected areas are many and complex. It is difficult to predict where the resistance will occur and it may be in a different area every time. The major problem with drug resistance is that it has been shown to reduce the effectiveness of the drugs. In addition, resistant strains can spread over great distances which leads to even more problems with drug resistance.
Some groups are concerned about a number of factors including:
Children especially have a greater risk of dying from malaria than adults. The most common age that children die from malaria is between the ages of 5 and 9 years old and the most common causes for death are meningitis, haemorrhage or pneumonia. There are a number of steps that are taken by the government in order to try and reduce the amount of children dying from malaria. For example, they can give mosquito nets to people who work in rural areas and protect them with insect repellent.
Malaria is widespread in many tropical countries but it is not usually as bad as what is seen in some of the African countries. However, there are still some places where proper measures cannot be used to prevent the disease because of difficult access to health care facilities or other reasons including political problems.
It is estimated that there are over 300 million people living in areas that have a high risk of malaria. In addition, it is estimated that at least 500 million people live in areas where they have a moderate risk.
A number of methods such as:
Mosquito nets are different from other methods because they do not kill the mosquitoes, instead they keep them away from people. Around 65% of all malaria cases are children who live in sub-Saharan Africa who have not yet been immunised with anti-malaria medication.
During 2000 there were about 30 reported cases of malaria in Australia and two cases in New Zealand. However, these cases can also be spread by travellers coming back from Africa and South America where there are large numbers of malaria infected people.
The most common type of malaria that affects people in Australia is "Plasmodium falciparum" but there are some other types including "Plasmodium vivax" which cause more problems. The best way to prevent a person getting infected with malaria is to use insect repellent and to protect them from mosquito bites at night.
It is not safe to have a child sleeping outside at night in areas where malaria is present. People who are staying away from their homes for a longer time should also use insect repellent and protect themselves at night when they sleep in an area where there are mosquitoes.