Malaria Hosts

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QUESTION

Which are malaria hosts and how does malaria have an effect on one of them?

ANSWER

The parasite which causes malaria (called Plasmodium) requires two different hosts—a vertebrate intermediate host, such as a human, and an insect definitive host, also known as the vector. For the types of malaria which infect humans and other mammals, the vector is always a mosquito of the genus Anopheles.

However, there are other types of malaria which infect birds and reptiles, and these can use other genera of mosquito as their vectors, and some parasites closely related to Plasmodium can even use sandflies and other types of insects as their vectors too.

In humans, malaria usually causes disease, characterized by high fever, chills, aches and nausea. However, the presentation of symptoms and their severity depends on a number of factors, such as the type of Plasmodium (P. falciparum is the most dangerous to humans), the immune status of the host and the infective dose received from the vector.

Many mammals are also susceptible to malaria, such as macaque monkeys, and with them as well the effect of the parasite depends on a number of factors. For example, for macaques in south-east Asia, many will be co-infected with several different types of malaria simultaneously, though none appear to cause disease. However, if macaques from other parts of tje world, such as the Himalayas, are experimentally infected with these same types of malaria, they will get sick and possibly even die. As such, evolutionary history also plays a part in terms of how severe malaria will be in a particular host.

For the insect vector, infection with malaria parasites does not appear to have a strong deleterious effect, though some studies have shown reduced survival in mosquitoes infected with malaria. Also, changes in behavior have been observed. For example, some studies have shown that mosquitoes which are infected with malaria are more likely to continue seeking for food (i.e. through biting a host) even if they have recently fed than mosquitoes which are uninfected, or infected with non-transmissable life stages of malaria. This suggests that in some way the malaria parasite is manipulating the vector’s behavior in order to increase its own chances of being passed on to a new host.

Do I need malaria tablets to live in Nigeria?

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QUESTION

Do I need malaria tablets to live in Nigeria? I was born and bred in the UK and want to go back to live in Nigeria for about 2 years, do I need malaria tablets?

ANSWER

It is not usually recommended to take malaria tablets for long periods of time (i.e. more than a few months). People living for extended periods in areas with malaria should focus on other methods of prevention, such as sleeping under a long-lasting insecticide-treated bednet.

The mosquitoes that carry malaria, Anopheles, feed mostly in the evenings and at night, so it is particularly important to protect yourself during these times. Screening windows and doors tightly can help prevent mosquitoes form entering, as can air conditioning inside the house (it makes the climate less suitable for the mosquitoes).

In many parts of Africa, insecticide is sometimes sprayed indoors, again to prevent mosquitoes from being inside the house. Personal protection is also important; wearing long-sleeved clothing, particularly at dawn, dusk and at night, can prevent mosquitoes from biting you, as can wearing mosquito repellent, particularly kinds containing the chemical DEET.

Regarding tablets to prevent malaria, if you really want to pursue this option, the only medication which is recommended for long-term use is doxycycline, but you should consult with your doctor about its suitability for periods of longer than 6 months, and they should also explain to you the possible side effects associated with taking it.

While the above mentioned forms of prevention should be the mainstay of your efforts to avoid malaria, it is also important to know what the symptoms are and what to do if you suspect you might be infected.

Malaria is characterized by high fever, chills, aches and nausea most commonly, and if you think you may be infected, you should immediately go to a doctor or a clinic for diagnosis. The doctor/clinician should take a blood sample and either look at it under a microscope to look for malaria parasites or they will use a drop of blood in a rapid diagnostic test. In both cases, you should only take medication to treat malaria if you are positively diagnosed.

Malaria Effect on Host

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QUESTION

What is the effect of malaria on host?

ANSWER

In the human host, malaria can often make a person very sick, though the exact symptoms and severity of the disease depends on the type of malaria (five different kinds of malaria infect humans). Many people will have a high fever, chills, nausea and body aches. In a symptom very typical of malaria, a patient will experience cyclical fever, with periods of no fever in between, lasting between one and two days. In infections with Plasmodium falciparum, the most dangerous kind of malaria, patients may experience impaired consciousness, a sign of “cerebral malaria”, which can lead to loss of consciousness, coma and even death.

In terms of the mosquito host (more commonly called the vector), the insect does not experience “illness” in the same way as the human host, and the parasite does not seem to have a particularly negative effect on the mosquito. However, some research has shown that infection with malaria may cause a mosquito to seek out blood meals more frequently, which scientists argue is an adaptation of the malaria parasite to ensure that its life cycle is continued.

What is Malaria?

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QUESTION

What is malaria?

What is the parasite that causes malaria?

ANSWER

Malaria is a serious and sometimes fatal disease caused by a parasite, of the genus Plasmodium, that commonly infects a certain type of mosquito (of the genus Anopheles) which feeds on humans. People who get malaria are typically very sick with high fevers, shaking chills, and flu-like illness. Four kinds of malaria parasites can infect humans: Plasmodium falciparum, P. vivax, P. ovale, P. knowlesi and P. malariae. Infection with P. falciparum, if not promptly treated, may lead to death. Although malaria can be a deadly disease, illness and death from malaria can usually be prevented.

Malaria Recurrence

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QUESTION

I had malaria 5 months back it has again reoccurred. this time there has been increase in the size of the spleen. As of now it is being treated but I fear of getting it again. Is it true the malaria which i am down with reoccurs every 6- 8 months ??? Local people call it as registered malaria.. .

ANSWER

There certainly are types of malaria that can reoccur relatively regularly, at various intervals. This malaria is caused by one of two species, either Plasmodium vivax or Plasmodium ovale.

With both, it is important to get it diagnosed via a blood test with a doctor before getting treated again, to make sure it is indeed a relapse of the same malaria, and not a new infection with a different kind, or indeed some other disease (the symptoms of malaria can often be confused with other infections).

There is also medication that can be taken to prevent future relapses and re-occurrences—it is called primaquine, so you should talk to your doctor about the possibility of taking this medication. Please note it is not suitable for people who have G6DP deficiency, so you should be tested for that before taking it.

Long and Short Term Effects of Malaria

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QUESTION

What are the long term and short term effects of malaria in brief please?

ANSWER

The symptoms of malaria as an acute infection vary somewhat depending on the type of malaria, but usual signs include high fever (often in a cyclical pattern, with fever one day, then no fever for one or two days, then a recurrence of fever), chills, body aches and nausea.

For Plasmodium falciparum, the most deadly form of malaria, the infection can progress rapidly if left untreated, with organ failure, impaired consciousness, coma and even death occurring as quickly as a few days after the onset of symptoms.

If the patient is able to survive the infection, or gets treatment in time, there are usually no long term affects of malaria infection. Some people who have suffered severe cerebral malaria (from P. falciparum) may experience some longer term neurological effects. Other types of malaria, such as P. ovale and P. vivax, can form dormant life stages which hide in the liver for weeks, months or even years, leading to relapse at a later date. However, apart from these recurrences, there are also no long term effects of infection with these types of malaria.

Vaccine for malaria? Differences with yellow fever?

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QUESTION

Is there a vaccine to prevent malaria?
What is the difference between yellow fever and malaria?

ANSWER

In answer to your first question, no, there is not currently a vaccine available to prevent malaria. The best current candidate, the RTS,S vaccine which was developed by GlaxoSmithKline, is currently undergoing Phase III clinical trials in Africa. Although preliminary results showed up to a 50% rate of protection against malaria in some age groups, the trials will not conclude until 2014 and so full results will not be known until after that date.

As for your second question, while yellow fever and malaria are both transmitted by mosquitoes, they share few other similarities. Yellow fever is caused by a virus, for example, whereas malaria is caused by a single-celled parasite of the genus Plasmodium. The group of organisms that Plasmodium belongs to is often called “Protista” (the exact grouping and classification constantly changes!), and they more generally belong, based on cell type, to the Eukaryotes, an enormous group of organisms which also includes all mammals and even humans! Viruses, on the other hand, are tiny pieces of genetic material wrapped in a protein coating, and can hardly be described as alive in a conventional sense.

While both yellow fever and malaria are transmitted by mosquitoes, yellow fever is transmitted by the genus Aedes, whereas malaria is exclusively transmitted by the genus Anopheles (at least in humans, and all other mammals for that matter).While spraying inside households may reduce the prevalence of  both types of mosquitoes, Aedes mosquitoes tend to feed during the day, so sleeping under an insecticide-treated bednet is less protective against yellow fever than it is against malaria. Also, a vaccine is available for yellow fever (and has been available for over 50 years), whereas as I describe above, no such vaccine yet exists for malaria.

Finally, while superficially the symptoms of yellow fever and malaria may seem similar (fever, nausea, aches), other manifestations of the disease can be very different. Yellow fever is technically considered a hemorrhagic disease, since it can cause increased tendency to bleed in patients. Also, in some patients, the initial symptoms are followed by an acute liver phase, causing jaundice which can turn the patient yellow (and hence the name). Malaria can also affect the liver, and cause ild jaundice, but usually not to the extent of yellow fever.  Once a patient has been diagnosed with yellow fever, there is no specific treatment, and the patient is merely treated based on symptoms, to ease their discomfort. Vaccination is the mainstay of control of this disease, and has been very successful in many places; the total number of worldwide cases is estimated by the World Health Organization to be around 300,000, with 20,000 deaths, mainly in Africa.

The burden of malaria is also mainly felt in Africa, though the number of cases and deaths is vastly higher – globally, there are approximately 200 million cases of malaria in 2010, with almost 700,000 deaths. Along with the general symptoms of fever and nausea, the most dangerous manifestation of malaria is when it causes cerebral symptoms; this is usually only caused by Plasmodium falciparum malaria, and can lead to impaired consciousness, coma and even death. Also in contrast to yellow fever,  the mainstay of control is a combination of prevention (mostly with vector control, i.e. using bednets, indoor residual spraying and destruction of breeding habitats and larvae) and treatment (using a variety of medications).

What Food Should I Eat for Malaria

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QUESTION

What food I eat in malaria?

ANSWER

If you mean what foods should you eat while you are suffering from malaria, then there are no specific diet specifications. Since many people feel nauseous and sick to their stomach while they are suffering from the disease, it may be hard to get people to eat anything at all – however, it is very important that the patient takes in a lot of fluids (water, diluted juice, herbal tea) in order to keep from getting dehydrated. If they are able to eat small amounts of food, that will also help to keep their strength up. Plain foods such as rice or dry toast may be the easiest for the person to digest, without feeling more nauseous.

First Malaria Outbreak

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QUESTION

When was the first ever outbreak of malaria?

ANSWER

Malaria has actually been known in human populations for thousands of years, so the first ever outbreak occurred long before any records were kept. The ancient Chinese recorded the symptoms of malaria in a medical manuscript which dates back to 2700 BCE, so almost 5000 years ago!

The symptoms of malaria were also known to the ancient Romans, Greeks, Egyptians and native peoples of the Americas, though none of them fully understood the cause of the disease or how it was transmitted. That information was discovered in the late 19th century, by Charles Louis Alphonse Laveran, who first observed malaria parasites in the blood of a patient and attributed them to the disease, and by Ronald Ross, who demonstrated that the malaria parasite was transmitted by mosquitoes.

What Causes Malaria

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QUESTION

What are the causes of malaria?

ANSWER

Malaria is caused  by infection with certain single-celled parasites of the genus Plasmodium. Specifically, there are five species which infect humans: P. falciparum (the most severe and dangerous form of malaria), P. vivax, P. ovale, P. malariae and P. knowlesi.

The symptoms of the disease occur when the parasite enters the blood stream (after a brief 1-3 week period of development in the liver) and begins to enter red blood cells, reproduce inside them, and then burst out, destroying the cell. The debris caused by this bursting, as well as various other aspects of the process, cause the body to mount an intense immune reaction which results in high fever, chills, aches and nausea. For P. falciparum infection, the infection is particularly severe because the parasite causes red blood cells it infects to stick inside the small blood vessels that lead to major organs, reducing blood flow and causing oxygen deprivation. When this occurs in the blood vessels in the brain, the result is impaired consciousness, unconsciousness, coma and even death – hallmarks of what is known as “cerebral malaria,” which is implicated in many of the deaths related to malaria each year.