Recurring Malaria

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QUESTION

I had malaria twice when I was 4 and 8 years old. I am 50 years old now but I have severe chills at least once or twice a month, muscle aches, fatigue severe head aches for the past 10-15 years with no apparent cause and my I take head ache medication for migraine (maxalt and excedrim) and my chills and fatigue is getting more frequent. I had no other history of any diseases. Is this symptoms a possible recurrent malaria.

ANSWER

Thanks for your question. One of the most common symptoms of malaria is high fever, which comes in cycles with chills in between. Without fever, it is unlikely that you are suffering from malaria.

However, there are some forms of malaria which can cause relapses. Specifically, Plasmodium vivax and P. ovale can form dormant liver stages which can then re-enter the blood causing a relapse of malaria infection and a recurrence of symptoms. To diagnose malaria in your case, next time you have an episode of chills, go to your doctor and ask for a blood test to check for malaria. S/he will either look at your blood under the microscope or perform a rapid diagnostic test, which tests for malaria-specific proteins, called antigens, in your blood.

In either case, it will tell you whether you have malaria, and which kind. If you have one of the relapsing kinds (P. vivax  or P. ovale) then you may be able to take a course of a drug called primaquine which kills the dormant liver forms of the malaria parasite and thus prevents future relapses. However, people with G6DP deficiency should not take primaquine, so you should be tested for this deficiency prior to taking the drug.

Paludrine/Avloclor Anti Malaria Travel Pack

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QUESTION

Is this anti malaria travel pack suitable for Borneo?

ANSWER

This kit is NOT appropriate for preventing malaria in Borneo. Avloclor contain chloroquine phosphate, and some types of malaria present in Borneo are resistant to chloroquine.

The CDC recommends that travelers to Malaysian or Indonesian Borneo should use atovaquone-proguanil (Paludrine contains proguanil, but the drug Malarone contains the combination of proguanil and atovaquone in one pill), mefloquine (sold under the brand name Lariam) or doxycycline.

Each of these different types of prophylaxis (preventative medication) has its advantages and disadvantages: Malarone is very expensive but many people consider it to have the fewest side effects; Lariam has been associated with severe side effects and is not recommended for people with a history of mental illness, but only needs to be taken once a week (the others require a daily pill); and doxycycline is cheap but may produce sun sensitivity.

When you return from your trip, please take a moment to share your experiences with anti-malarial medication by taking our malaria survey. We will compile all the results and post them on MALARIA.com, so visitors to the site can be informed about the preferences and side effects experienced by other members of the public who have used different forms of prophylaxis.

Evolution of Malaria

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QUESTION

how did malaria evolve?

ANSWER

Malaria in humans probably evolved independently several times, and both times likely due to a cross-over event from a closely related primate malaria. For example, Plasmodium vivax is evolutionarily closely related to several species of malaria found in macaque monkeys in south-east Asia, and so a cross-over of one of those species into human, with subsequent adaptation and speciation, is one hypothesis as to the origin of P. vivax. Conversely, some people argue that P. vivax emerged in Africa, due to the high prevalence of certain genetic traits in African populations (such as the Duffy negative antigen), which protect against P. vivax.

In contrast, P. falciparum is agreed to have emerged in sub-Saharan Africa, and likely in the Congo basin, though the exact source of its origin has been under recent scientific dispute. Until 2010, it was thought that P. falciparum had crossed over to humans from chimpanzees, as chimps are known to be infected with P. reichenowi, a species very closely related to P. falciparum. However, a paper was published in 2010 which had sampled Plasmodium parasites of gorillas and revealed new species of Plasmodium which are even more closely related to P. falciparum, suggesting that the cross-over occurred from gorillas to humans.

As you can see, humans are not the only primates to get malaria; many species of monkey and ape are also susceptible to Plasmodium species, and even lemurs have their own suite of Plasmodium parasites. Among the mammals, rodents also can get malaria, and bats are infected with Hepatocystis, a malaria-like parasite which also infects hippos, primates and rodents. However, no other species of mammal appears to be susceptible to Plasmodium/Hepatocystis, and the reasons for this are not entirely clear.

Plasmodium probably crossed over to mammals from birds or lizards, both of which are infected with a vast number of species of Plasmodium. It is unclear in which of these groups Plasmodium first emerged, though it likely evolved originally from another type of blood-borne parasite called Leucocytozoon, which infects birds and uses blackflies (genus Simulium) as vectors.

A sister group to Plasmodium, called Haemoproteus, also evolved from Leucocytozoon but utilises a variety of different vectors, including mosquitoes, biting midges (Culicoides), louse flies (Hippoboscidae) and tabanids (Tabanidae). Plasmodium, by contrast, exclusively uses mosquitoes as its vectors (apart from one species of lizard Plasmodium, P. mexicanum, which uses sandflies), but while mammalian Plasmodium is only transmitted by Anopheles mosquitoes, bird and lizard Plasmodium can be transmitted by Culex, Aedes, Culiseta, Anopheles, Mansonia and Psorophora. As such, understanding the patterns of vector and host switches within Plasmodium and related taxa can actually provide interesting insights into the genus’ evolutionary history.

Plasmodium

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QUESTION

Is Plasmodium a bacteria. Why?

ANSWER

No, Plasmodium is actually a protozoan—that is, a single-celled organism that is usually microscopic and belongs to the Domain Eukaryota (which also includes all plants and animals, but excludes bacteria and archaea). More specifically, Plasmodium belongs to the Apicomplexa group of protozoans, which are characterised as being parasites of animals, and possessing several unique characteristics, such as an apical complex structure used for invading host cells, and from which the group derives its name.

Protozoans differ from bacteria in terms of evolutionary history as well as a number of key characteristics. For example, protozoans, like all eukaryotes, possess a membrane-bound nucleus and organelles, neither of which are seen in bacteria. Bacteria, moreover, can produce their own food (they are autotrophic), whereas protozoans tend to be heterotrophic and rely on other organisms for food.

How does one catch malaria?

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QUESTION

How do you get malaria?

ANSWER

Malaria is caused by a parasite called Plasmodium, which is transmitted via the bites of infected mosquitoes. In the human body, the parasites multiply in the liver, and then infect red blood cells. Usually, people get malaria by being bitten by an infective female Anopheles mosquito. Only Anopheles mosquitoes can transmit malaria and they must have been infected through a previous blood meal taken on an infected person. When a mosquito bites an infected person, a small amount of blood is taken in which contains microscopic malaria parasites. About 1 week later, when the mosquito takes its next blood meal, these parasites mix with the mosquito’s saliva and are injected into the person being bitten.

Because the malaria parasite is found in red blood cells of an infected person, malaria can also be transmitted through blood transfusion, organ transplant, or the shared use of needles or syringes contaminated with blood. Malaria may also be transmitted from a mother to her unborn infant before or during delivery (“congenital” malaria).

Dangerous

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QUESTION

Why malaria so dangerous?

ANSWER

Malaria can be dangerous for a number of different reasons, some of which relate to each other. First of all, there are five different types of malaria that infect humans, and each varies in terms of its severity and potential for severe consequences. Even within these types, the severity of the disease caused (termed “virulence” by scientists and doctors), can even vary by strain or geography. Generally, the most dangerous form of malaria is caused by Plasmodium falciparum. One reason why this species of malaria is so dangerous is that is replicates very quickly in the blood. This means that infection levels can build up very quickly; if a person infected with P. falciparum does not get diagnosed and treated within a few days of feeling sick, the infection can progress to a point where the disease becomes very severe. This rapid accumulation of infection is also observed with P. knowlesi, a much rarer form of malaria found in south-east Asia. The parasites of P. knowlesi have a 24-hour reproductive cycle in the blood, the quickest for any type of malaria that infects humans. However, P. falciparum also has other characteristics which make it even more dangerous, and which do not occur with P. knowlesi. For example, when P. falciparum infects red blood cells, it causes their shape to change, and makes them “sticky”. This stickiness causes the red blood cells to become lodged in the blood vessels leading in to major organs, in a process known as sequestration. Sequestration creates blockages of these blood vessels, reducing blood flow and resulting in oxygen deprivation. When this process occurs in the blood vessels in the brain, the outcome is known as cerebral malaria, characterised by impaired consciousness, coma and even death. It is this pathology which is associated with most cases of severe malaria, and causes the most number of deaths.

However, if treated promptly with the correct drugs, even P. falciparum malaria is usually easily controlled. Therefore, one of the additional reasons why malaria is so dangerous is that in many places, and particularly sub-Saharan Africa, people do not have access to medication, or not the right types of medication. Many strains of P. falciparum have become resistant to chloroquine, once the first line treatment for malaria, and so this drugs is now ineffective in many cases. Instead, the World Health Organisation recommends now that artemisinin-based combination therapies (ACTs, such as Coartem) should be given as first-line treatment against all uncomplicated malaria, to prevent additional resistance from developing.

Thalassaemia and Malaria

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QUESTION

How can Thalassaemia effect Malaria infection?

ANSWER

Thalassaemia is the name given to a group of inherited genetic blood disorders, which result in reduced or no synthesis of one of the globin protein chains that combine to make haemaglobin. Haemaglobin is used to carry oxygen throughout the body and to its organs.

Thalassaemia can result in anaemia; in some cases, this is severe enough to require periodic blood transfusions. There has long been a hypothesis that thalassaemia might have persisted due to conveying protection against malaria infection; this was suggested due to the geographical distributions of populations with high prevalence of the alleles (gene types) that cause thalassaemia and areas with high levels of malaria transmission. However, scientifically confirming this association has proved challenging.

A recent study from Kenya demonstrated that children with either one copy of the thalassaemia allele or two copies appeared to have a reduced incidence of severe malaria, fewer deaths from malaria and were hospitalized less frequently for malaria. However, they were just as likely as non-thalassaemic children to have mild or sub-clinical malaria, and the same levels of parasitaemia (numbers of parasites in the blood).

A contrasting study from Vanuatu observed higher incidences of severe malaria in children with thalassaemia, though one potential confounding factor in comparing these studies is that the Vanuatu study looked at both P. falciparum and P. vivax, whereas the Kenya study only looked at P. falciparum malaria.

The difference is significant: one of the proposed mechanisms by which thalassaemia protects against malaria is by preventing modification of the surface of red blood cells, which causes the red blood cells to become “sticky” and sequester within the blood vessels that feed major organs, eventually restricting blood flow and causing major complications. This sequestration is only observed to occur during infection with P. falciparum, and so thalassaemia might not be as protective against other forms of malaria. More empirical research from the field is needed to understand the mechanisms relating malaria infection with thalassaemia more fully.

Malaria Parasite Picture

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QUESTION

Please show parasites pictures.

ANSWER

The first plate below shows various stages of the life cycle of Plasmodium falciparum, the most deadly form of malaria, and the most commonly found type in sub-Saharan Africa. Below that, a similar plate shows a series of images of Plasmodium vivax, the most widespread type of malaria.

A: The stages of P. falciparum. 1: Normal red cell; Figs. 2-18: Trophozoites (among these, Figs. 2-10 correspond to ring-stage trophozoites); Figs. 19-26: Schizonts (Fig. 26 is a ruptured schizont); Figs. 27, 28: Mature macrogametocytes (female); Figs. 29, 30: Mature microgametocytes (male). Illustrations from: Coatney GR, Collins WE, Warren M, Contacos PG. “The Primate Malarias”. Bethesda: U.S. Department of Health, Education and Welfare; 1971. Reproduced here courtesy of the CDC (www.cdc.gov)

 

 

Where is malaria found?

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QUESTION

Where is malaria found?

ANSWER

Malaria is found throughout the world’s tropical and sub-tropical areas, and mainly in Central and South America, Africa, Asia and the Indo-Pacific region. It is most common in tropical regions, where transmission occurs year-round; in sub-tropical and temperate areas, transmission may only occur during seasons that have appropriate climatic conditions. This includes sufficiently high temperature and water availability for the growth and development of the mosquito, which transmits the disease. Currently, the greatest burden of the disease is felt in sub-Saharan Africa, where over 90% of deaths due to malaria occur. The map below shows the estimated risk for malaria across the world, courtesy of the World Health Organisation.

Global_Malaria_2010_WHO

Map of the global distribution of malaria, courtesy of WHO (www.who.org)

Dietary recommedations

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QUESTION

Can I have the dietary recommendations please.

ANSWER

I am afraid I do not completely understand your question. There are no known dietary measures that can be used to prevent malaria infection, nor are there and recommended ways of treating malaria with common foods. In the past, people drank tonic water, which contained quinine, as a way of preventing and treating malaria. However, in modern times, tonic water contains very low levels of quinine, insufficient to protect against malaria. More effective means of prevention, such as prophylactic medication and sleeping under a long-lasting insecticide treated bednet, are recommended instead.