Malaria Fever

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QUESTION:

How many days will the fever last?

ANSWER:

There is no set amount of time for the duration of a malaria fever, and in fact it will depends on several factors, namely the type of malaria the patient has, their level of acquired immunity, whether they were taking preventative medicine for malaria (prophylaxis) at the time of infection and how quickly they receive appropriate treatment.

There are, however, known “cycles” to the progression of fever during a malaria infection. Plasmodium falciparum, P. vivax and P. ovale, three of the types of malaria that normally infect humans, are known as “tertian” malarias, as they produce fevers that peak every two days. P. falciparum, due to its severity and rapid increase in the human host, can sometimes present with more frequent, or even constant, fever. P. malariae, on the other hand, is considered a “quartan” malaria, as it produces fever in approximately three-day cycles.

Illness from Uganda trip

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QUESTION:

I just came back from a visit to Uganda Africa. I was unable to take Malarone as I had bad side effects. Vomiting. I was only exposed once when we walked into a swampy rain forest. This of-course was the only day I did not have repellent. We were taking the kids on a nature walk and the German volunteer got a little lost. I ran as fast as could out of the area. Started to feel tired and weak 7 days later, getting severe headaches and going from hot to cold. 5 kids ended up with Malaria shortly after our walk. (I found this out after my return).

A missionary on the plain said I must likely had malaria and gave me Lumartem. By the time I got home I was having sever diarrhea and real bad body aches, low grade fever. The doctor here took my blood but reported my results would take 7 days. I started taking the Lumartem, & I felt better, the runs slowed down the boy aches lessened. Now I am finished with my 3 day prescription Feel pretty good compared to how I felt b4. Still have stomach cramps and small runs. What now? Should I go have a blood test to see if its gone or just wait and see???

ANSWER:

Considering you were in Uganda, it is not unlikely that you didn’t also pick up some sort of intestinal bug or parasite, which might be responsible for the residual runs and cramps. However, it is certainly important to take a blood test to ensure that you have completely cured the malaria infection; P. falciparum is common in Uganda, and causes a very severe form of malaria. While it can’t come back directly once it has been cured, if treatment is not entirely successful small numbers can remain in your blood stream and then start reproducing again once you have stopped taking medication, resulting in what is called “recrudescence” of the infection.

If possible, try to find out from the doctor that performs the blood test what type of malaria you had/have, as this will also determine whether you need additional medication (called primaquine) to prevent recurrence or relapse of the infection at a later date. Recurrence is due to a dormant phase of the malaria parasite hiding out in your liver; while P. falciparum cannot produce these dormant phases (and therefore can only relapse if the initial blood infection is not completely cured), two other malaria parasites, called P. vivax and P. ovale, can have liver stages, and so you may need to take primaquine if you are found to have been infected with either of these types.

Primaquine for Malaria Treatment

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QUESTION:

In India what is the duration of primaquine therapy in confirmed Malaria infection?

ANSWER:

Primaquine is usually used to kill the hypnozoite stages of Plasmodium vivax or P. ovale. This life stage of the malaria parasite can reside, dormant in the liver’s hepatocyte cells, even after the patient has completed the normal course of treatment for the infection; at this stage, the patient might not have visible malaria parasites in the bloodstream, and thus be considered “cured”. Despite this, the patient is actually potentially at risk from recurrence of malaria if the dormant liver hepatocytes re-enter the blood stream.

For this reason, patients with P. vivax or P. ovale should complete a course of primaquine in addition to the standard malaria treatment offered. The usual adult dosage for primaquine is 15-30mg base, taken orally, once a day for 14 days.

Is there malaria in North America?

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QUESTION:

Are there malaria-infected mosquitoes in North America?

ANSWER:

North America is usually defined as including Canada, the United States and Mexico. Of these, Mexico has known regions of regular malaria transmission; specifically the regions bordering Guatemala and Belize in the south (Chiapas, Quintana Roo and Tabasco), rural areas in the tropical lowlands slightly further north (parts of Oaxaca, Nayarit and Sinaloa) and a very localised section of northern Mexico, located across the states of Chihuahua, Sonora and Durango. Travellers to these areas are recommended to take measures to prevent against malaria infection, such as minimising mosquito bites or taking prophylactic medication. Both P. falciparum and P. vivax are known to be transmitted in Mexico, so you should consult with a travel physician before deciding which form of preventative (prophylactic) medication to take, depending on the length of your stay, your budget and the type of malaria most commonly found in the area to which you are travelling.

Malaria was once also widespread in the southern USA, though a concerted public health campaign that started in 1947 (mainly consisting of reducing the number of mosquitoes through insecticide spraying and control of stagnant water bodies) greatly reduced transmission and led to the disease being considered eliminated by the 1950s. Occasionally, small pockets of transmission will be reported, though stringent diagnosis and treatment quickly places these outbreaks under control once more.

However, there are additional cases of malarial mosquitoes occasionally also reported even from northern parts of the United States and Canada; these are when mosquitoes are accidentally transported from malarial regions, for example in airplanes, in luggage or in shipping containers. These mosquitoes almost never transmit the disease to people, and in most temperate regions, do not live long enough to be a public health threat or to enable the persistance of the disease.

Causes of malaria, treatment with drugs and emerging resistance

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QUESTION:

What is malaria and what causes it besides bacteria? What is the name of the causal agent for malaria, which drug is used to cure it and how do the pathogens become resistant to the drugs?

ANSWER:

There are many questions in there! Malaria is actually caused by a single-celled animal, called a protozoan; it’s not a bacterial disease. There are different species of these protozoans, which form a genus called Plasmodium; the different species cause different types of malaria, for example Plasmodium falciparum, the most deadly and severe form, and Plasmodium vivax, which is widespread throughout the world but is a less acute infection. These different forms of malaria are each treated with different medications, depending on what is most effective and available; P. vivax, for example, can be treated with chloroquine, whereas in many places, P. falciparum has become resistant to this drug. In areas where resistance to chloroquine has emerged, other drugs are used; in Africa, artemisinin-based combination therapies (ACTs) are commonly used against chloroquine-resistant P. falciparum. Other drugs used to treat malaria include quinine compounds such as quinine sulphate, mefloquine, sulfadoxine-pyrimethamine and medications combining proguanil with atovaquone (marketed as Malarone).

The emergence of resistance to these drugs is a worrying phenomenon with respect to malaria; it is such a widespread and deadly disease, that the consequences of failed treatment are very high. Resistance can be caused by many factors, at the level of the drug, the human host, the mosquito host and also the malaria parasite itself. For example, poor drug compliance during treatment can lead to a failure to clear an infection completely, allowing the remaining parasites, which were less susceptible to the drug, to survive and reproduce. With successive generations, natural selection will lead to the evolution of strains of malaria parasites which are firmly resistant to that drug. The same process occurs when mass drug administration programmes, for example in areas of high malaria endemicity, give people sub-therapeutic doses of medication (in other words, doses of the drug that are too low to kill the parasite). Another problem is when people are not checked for their infection status after having been treated for malaria; if treatment fails for some reason, they will still have parasites in their blood, and should be treated again to ensure that all the malaria has been killed. If this doesn’t happen, the parasites can carry on reproducing, as in the processes described above. For these reasons, it is crucially important for people to be given accurate doses of medication, to ensure that they complete the full course of treatment, and that once treatment has been completed, they are accurately tested as negative for the malaria parasite. Finally, there are factors related to the affinity of the malaria parasite to its vector mosquito hosts which can lead to the emergence of drug resistant strains. For example, it has been shown that strains of malaria which are resistant to chloroquine are better able to survive and reproduce inside their mosquito hosts, leading to a greater population size of resistant parasites compared to drug-susceptible ones. It is for these reasons that malaria treatment and control programmes are now being very careful with the ways in which they administer drugs and monitor infections, in order to limit any further reisstance developing; similarly, pharmaceutical and biochemical researchers are constantly on the look-out for new compounds or methods of killing malaria parasites, which can be developed into new forms of treatment.

Causes of malaria

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QUESTION:

What are the causes of malaria?

ANSWER:

Malaria is caused by parasites of the genus Plasmodium. These are single-celled animals known as protozoans (from the Greek ‘protos’ and ‘zoia’ which together mean ‘first animal’) and they are transmitted via mosquitoes that feed on blood; the parasites need both mosquito and human hosts to complete their life cycle (see below a graphic of the complete life cycle, courtesy of CDC). In the process of reproducing, the malaria parasites destroy human red blood cells, which is what causes the clinical symptoms of disease that the patient experiences, such as fever, headaches and nausea.

Malaria life cycle CDC

Generalized malaria life cycle (courtesy of CDC: www.cdc.gov)

There are four main species of Plasmodium that infect humans: P. falciparum, P. vivax, P. malariae and P. ovale. P. falciparum causes the most severe manifestations of the disease and is responsible for the majority of human deaths from malaria. There is a fifth type of malaria, P. knowlesi, which usually infects macaque monkeys but has been known to pass into humans as well.

For more on this, please see Christina Faust’s excellent blog post about her research.

What are the strains of malaria?

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QUESTION:

What are the different strains of malaria?

ANSWER:

Malaria is caused by small, single-celled parasites called protozoans, and specifically ones of the genus Plasmodium. There are many, many species of Plasmodium, which infect a wide variety of different species, from lizards and birds to rodents, bats and primates. Of all the species of malaria, four main ones infect humans – these are P. falciparum, P. vivax, P. ovale and P. malariae. A fifth species, P. knowlesi, usually infects macaque monkeys in South East Asia but has been known to cross over to humans. Each of these species causes slightly different manifestations of the disease in humans, and even within the species, there are regional strains and variations. Probably the most distinct internal division within a malaria species is within P. ovale, where two sub-species are currently recognised: P. ovale curtisi and P. ovale wallikeri. These two forms are identical morphologically (that is, in the way they look under the microscope) but can be differentiated genetically.

Can malaria come back?

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QUESTION:

If you had malaria once, can it return for a second time without being in a malaria area?

ANSWER:

Yes. There are several ways in which malaria can come back without being re-infected again. The blood forms of the parasites can sometimes persist at low numbers, so that the patient no longer has any symptoms; if these blood forms begin to reproduce again, the patient will once again begin to feel sick and have malaria symptoms. This is known as ‘recrudescence’ and can occur as quickly as within the same year as the initial infection but also as long as fifty years later, depending on the type of malaria! Treating the infection thoroughly, and being tested for parasites after treatment, is one way to avoid recrudescence.

The other way in which malaria can come back is through ‘recurrence’, which is when the malaria parasite enters a dormant phase which resides in the liver. Again, the patient will feel no symptoms while the malaria is dormant, but once these liver stages change into the blood stages and reproduce, symptoms will reoccur. This form of relapse only occurs with Plasmodium vivax and P. ovale infections, and can be prevented through taking an additional form of medication, called primequine, at the same time as the normal malaria drugs when diagnosed. This extra medicine kills the liver forms of malaria and thus prevents recurrence. For more details on this, please see the comments I made, on behalf of Dr Etty Villanueva, on the post ‘Malaria Symptoms and Causes’, published on the 22nd of February, 2011.

Treatment for Malaria

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QUESTION:

How do you treat malaria?

ANSWER:

Malaria can be treated with a number of different types of medication; which one to use depends on the type of malaria you have, as well as whether resistant strains are known to occur in your area. Below I have copied the response I wrote to a similar question on malaria treatment, posted on the 2nd of May, 2011:

In most cases of non-Plasmodium falciparum malaria (the most deadly form of malaria, found throughout the world but most prevalent in sub-Saharan Africa), and even in some places where P. falciparum has not yet developed resistance, treatment with chloroquine is sufficient.

The dosage will depend on body weight (usually approximated by age). Where there is a risk of chloroquine-resistant malaria occurring, treatment of non-complicated cases will usually consist of orally-administered artemisinin-based combination therapy (or ACT) – again, the dosage will depend on age/weight.

For severe malaria, parenteral ingestion of drugs is required. For the treatment of cerebral malaria, caused by P. falciparum, quinine is the traditional drug of choice, though artemisinin has also been shown to be effective. Anti-convulsants and anti-pyretics (to reduce fever) should also be administered.

In cases of infection with P. vivax or P. ovale, the parasite can become dormant in the liver and result in a relapse of the disease if not treated properly. As such, patients with either of these forms of malaria should also be treated with primaquine.

If you have, or suspect you have a health problem, you should visit a physician for a medical diagnosis and treatment.

Started Late on Anti-malaria Medication

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QUESTION:

I’m in a malarious country and I had no idea about anti-malarials until I got here, so I started taking anti-malaria(doxycicline) two weeks late. It has been three weeks since I started taking the medicine. Do you think it would work or should I stop taking it?

ANSWER:

It depends a bit on where you are, and what types of malaria are in your region. Plasmodium falciparum usually takes between 7 and 14 days for symptoms to develop after exposure; P. vivax and P. ovale take between 9 and 14 days. P. malariae, on the other hand, sometimes doesn’t show symptoms until 30 days after infection. However, the most acute and dangerous form of malaria is that caused by P. falciparum; as such, if you haven’t had any symptoms since you started taking anti-malarials three weeks ago, you should be ok, and it certainly would be advisable that you continue with the preventative medicine while you remain in the malarial area.

It’s also worth mentioning that because of the lag between infection and symptoms, in many cases you need to continue taking antimalarials for some period of time after you leave the malaria zone. Of course, if at any point you start to develop symptoms, such as fever or chills, go to a hospital or see a doctor for prompt diagnosis.