Malaria Parasites Classification

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QUESTION

Where are malaria parasites classified?

ANSWER

The parasite that causes malaria comes from the genus Plasmodium, which is part of a Phylum of single-celled protist organisms called Apicomplexa. The Apicomplexans mostly posses an organ called an apicoplast, which is part of an apical structure designed to aid entry into a host cell. The Apicomplexa is split into two Classes, of which Plasmodium belongs to the Aconoidasida (lacking a structure called a conoid, which is like a set of microtubules), and then to the Order Haemosporidia, which contains parasites which invade red blood cells. Within this Order, Plasmodium belongs to the Family Plasmodiidae, which all share numerous characteristics, including asexual reproduction in a vertebrate host and sexual reproduction in a definitive host (a mosquito, in the case of the Plasmodium species that infect all mammals, including humans).

In the case of human malarias, the definitive host is often referred to as the vector. The family contains about twelve genera, of which one is Plasmodium, which itself is now often divided up into numerous sub-genera, and then again into hundreds of different species, of which five infect humans (P. falciparum, P. vivax, P. ovale, P. malariae and P. knowlesi).

Discovery of Malaria

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QUESTION

How was malaria discovered?

ANSWER

Malaria has long been known to human populations from across the world. In fact, the first mention of the symptoms of malaria comes from an ancient Chinese manuscript from 2700 BCE! However, the actual cause and mechanism of transmission of the disease was only discovered in the 19th century.

It was Charles Louis Alphonse Laveran, a French physician working in Algeria, who first observed the parasites that cause malaria in 1880, by looking at the blood of a patient that had recently died of malaria. However, at this point, it still wasn’t understood how malaria was transmitted. That was not discovered until 1897, when Ronald Ross, a British physician dedicated to curing malaria, observed malaria parasites in a mosquito that had been experimentally fed the blood of a patient infected with malaria. Working in India, Ross also later showed that mosquitoes could also transmit malaria to birds, if they had previously fed on the blood of birds which had malaria. In this way, he showed that mosquitoes of the genus Anopheles are responsible for transmitting malaria between hosts.

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).

Treatment of Malaria

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QUESTION

How is malaria treated?

ANSWER

Malaria can be a severe, potentially fatal disease (especially when caused by Plasmodium falciparum) and treatment should be initiated as soon as possible.

Patients who have severe P. falciparum malaria or who cannot take oral medications should be given the treatment by continuous intravenous infusion.

Most drugs used in treatment are active against the parasite forms in the blood (the form that causes disease) and include:

  • chloroquine
  • atovaquone-proguanil (Malarone®)
  • artemether-lumefantrine (Coartem®)
  • mefloquine (Lariam®)
  • quinine
  • quinidine
  • doxycycline (used in combination with quinine)
  • clindamycin (used in combination with quinine)
  • artesunate (not licensed for use in the United States, but available through the CDC malaria hotline)

In addition, primaquine is active against the dormant parasite liver forms (hypnozoites) and prevents relapses. Primaquine should not be taken by pregnant women or by people who are deficient in G6PD (glucose-6-phosphate dehydrogenase). Patients should not take primaquine until a screening test has excluded G6PD deficiency.

How to treat a patient with malaria depends on:

  • The type (species) of the infecting parasite
  • The area where the infection was acquired and its drug-resistance status
  • The clinical status of the patient
  • Any accompanying illness or condition
  • Pregnancy
  • Drug allergies, or other medications taken by the patient

If you have or suspect you have malaria, you should contact your doctor immediately.

Injections to Get Malaria

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QUESTION

I was wondering at one time did they give people shots to get malaria and then give them like I.V.S with some kind of medicine it the i.v. to counteract it, I know that some one that had ulcers of the eye and the eye specialist sent her home to her home hospital for i.v.s as he had given her a shot so she would get MALARIA, THIS would have been years ago, I don’t understnd the concept of giving her a shot for malaria and then give orders for her to have i.v.s.

ANSWER

The only reason I can think of for someone to be given an injection which might give them malaria, and then medication (perhaps in the form of an IV) in order to cure it is if they had volunteered to participate in a clinical trial, for example to test new malaria medications.

All clinical trials have to be approved by the medical research board of the country in which they are taking place, in order to ensure they comply with ethical considerations regarding patient rights, safety, etc. Many countries have an online database where clinical trials must be posted, so the public can be kept aware of what is going on. If you have such a registry in your country, you could look up whether a malaria treatment trial was conducted around the time that your friend received the injections. Otherwise, you could contact the hospital directly and ask if they participated in any trials.

Feeling Ill After Malaria Infection

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QUESTION

How soon after infection, will a person usually begin to feel ill?

ANSWER

There is a latent period, during which time the malaria parasites (which had entered the bloodstream via the bite of an infected Anopheles mosquito) migrate to the liver and undergo replication. The sporozoites (the life stage that enters the blood from the mosquito) differentiate in many merozoites, which are contained within a schizont in the liver cells. When the schizont ruptures, the merozoites are released and re-enter the blood, where they set about infecting red blood cells. Once in the red blood cells, the infected person will begin to experience symptoms—this is usually between 6-16 days after the initial infection, during which time the parasite is reproducing in the liver.

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.

Curing Malaria

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QUESTION

What is needed to cure malaria?

ANSWER

Malaria is usually cured through treatment with an anti-malarial drug. The World Health Organization recommends use of an ACT (artemisinin-based combination therapy, such as Coartem) as first-line treatment for all non-complicated (i.e. not severe) malaria, and especially P. falciparum malaria (which in most places is resistance to chloroquine, and also to mefloquine in some locations). For complicated, severe malaria, or in cases where the patient is unable to take medication orally, the recommended treatment is intravenous quinine.

Malaria in Southern Africa

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QUESTION

Which areas in southern africa harbour malaria?

ANSWER

Most of Namibia, Botswana and South Africa does not harbor malaria, either because it is too cold, too dry, or control measures have successfully eliminated transmission. However, malaria transmission is found in virtually all parts of Zimbabwe and southern Mozambique.

In addition, pockets of malaria transmission can be found in parts of the other countries of southern Africa, namely in northern Namibia (provinces of Kunene, Ohangwena, Okavango, Omaheke, Omusati, Oshana, Oshikoto, and Otjozondjupa and in the Caprivi Strip), in northern Botswana (Central, Chobe, Ghanzi, Northeast, and Northwest provinces) and also in the north-eastern corner of South Africa (north-eastern KwaZulu-Natal, with the southern-most limit of transmission corresponding with the Tugela River, Limpopo (Northern) Province, and Mpumalanga Province). Malaria is also transmitted in Kruger National Park.

Vaccine for Malaria

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QUESTION

Is there a vaccine to prevent malaria?

ANSWER

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.