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.

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).

Swelling of Lymph Nodes and Malaria

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QUESTION

I would like to know if swelling of lymph nodes in neck is any way connect to malaria?

ANSWER

Swollen lymph nodes are often a sign that the body is trying to fight off an infection, and so swollen lymph nodes are certainly sometimes observed in malaria patients. However, most malaria infections would also be associated with other symptoms, such as fever, chills, nausea and aches.

In some cases (but not all), malaria patients experience cyclical fever, whereby they have a high fever one day and no fever the next, but the fever returns on the third day, and the cycle continues. One type of malaria exhibits a cycle of fever one day, then no fever for two days, then fever returns on the fourth day. However, many patients do not experience these cycles, which means their symptoms are very similar to those for many other illnesses, which is why if you are in or have been visiting an area where malaria is transmitted and you have some of the above symptoms, it is very important to visit a doctor or clinic to get diagnosed for malaria. This can be done with a simple blood test, and the results are usually available very quickly. Then, if you are diagnosed as positive for malaria, the doctor can recommend appropriate treatment and instruct you in the proper way of taking it.

Fever and Body Aches with Malaria

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QUESTION

Is bad throat and fever with with body ache the symptom of malaria?

ANSWER

While fever and body aches are certainly some of the symptoms associated with malaria, a sore throat is well common, but could be the result of enlarged lymph nodes. It is important to note that these symptoms are also present with many other diseases; in fact, the symptoms of malaria are so general that sometimes it is difficult to diagnose, and a blood test should be performed to confirm that a patient is indeed suffering from malaria before treatment is given.

Joint Pain and Malaria

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QUESTION

Could an onset of joint pain and swelling plus hurting all over be a residual for someone who has had malaria?

ANSWER

Once someone has been treated for malaria, they should not experience any further residual effects, particularly if the infection was uncomplicated and treated using oral medication. Joint pain, swelling and pain could well be indications of another infection, and so medical advice should be sought immediately.