Current Status of Malaria

by

QUESTION:

What is the current status on malaria? And does P.knowlesi spp. pose a greater threat compared to the others? Does the number malaria cases increase every year globally? Is P. knowlesi spp. more dangerous than the others and why?

ANSWER:

I’ll answer your question about Plasmodium knowlesi first. So far, it is considered a relatively minor source of malaria in humans, as its natural host are macaque monkeys and so it is usually thought of as a “zoonotic” disease.Between 2000-2008, there were only been about 400 reported cases of P. knowlesi, all restricted to south-east Asia, and mainly Borneo. These figures are low compared to other forms of malaria, such as P. falciparum, which in Africa alone accounts for millions of cases a year, and close to a million fatalities. However, there are some causes for concern with regards to P. knowlesi.

First of all, it appears to be an emerging human infection; the first cases were traced back to the 1960s, with the number of cases increasing in recent years. While some of this increase is likely the result of higher accuracy diagnosis and awareness about malaria, it is also hypothesised that the increasing population density in forested areas of south-east Asia may also be leading to greater numbers of people being exposed to this parasite. Secondly, although easily treated with anti-malarial drugs, the life cycle of P. knowlesi is such that it reproduces very rapidly in the human host, causing cycles of fever every 24 hours (a so-called “quotidian fever”). This means that the infection can progress rapidly, becoming severe in a matter of days, and therefore requiring prompt treatment. Finally, although locally restricted to south-east Asia, P. knowlesi has become the dominant form of malaria in some of these areas, notably Sarawak. As such, although currently not a major source of malaria in the global human population, it is locally important to public health and moreover, more research is needed to determine why the number of cases has been on the rise.

As for your questions about the status of malaria globally, the number of cases annually is estimated to be around 250 million. The vast majority of these are in Africa. Over 700,000 people, mainly children under five, die from malaria each year. As for whether the number of cases is increasing or decreasing, this is hard to determine. For one, a large number of cases are not reported every year, making accurate estimates difficult. Secondly, the world’s population is growing, and it is growing at the greatest rate in Africa, where the majority of malaria cases occur. As such, even if the proportion of people with malaria decreases over time, due to health initiatives such as distributing long-lasting insecticide treated bednets or free treatment, the total number of cases may still rise. Another problem we face in the fight against malaria is climate change: as the world’s patterns of rainfall and temperatures change, new areas become susceptible to malaria transmission, putting more people at risk. However, what is very encouraging is that deaths from malaria seem to be decreasing on a global scale.

Malaria No More is an organisation dedicated to eliminating deaths from malaria by the year 2015; more information about their methods and some of their success stories can be found on the Malaria No More website.

Malaria After Blood Transfusion

by

QUESTION:

How many days does it take to become symptomatic after a blood transfusion of malaria infected blood to patient?

ANSWER:

This depends on the strain and burden of malaria parasites in the blood being transfused. Onset of malaria symptoms can be very rapid if infected red blood cells begin to rupture immediately, say within 24-48 hours, or conversely symptoms can be very delayed (days/weeks/months) if only a few parasites are transfused. Depending on strain, the malaria parasites may need to cycle through the liver to mature before they infect the red cells (such as in the case of Plasmodium vivax or P. ovale).  Then, depending on the strain (P. vivax most commonly), the infected red cell “burden” often needs to approach 0.5 to 1% before synchronized rupture of red cells and release of the parasites is sufficient to produce acute fever and symptoms.


Malaria Schizonts

by

QUESTION:

What is the difference between schizont of Plasmodium vivax and P. falciparum?

ANSWER:

P. falciparum schizonts tend to fill up to about two-thirds of the host red blood cell, and contain 8-24 merozoites (see image below for development of schizont). However, schizonts of P. falciparum are rarely seen in peripheral blood; instead, multiple, smaller rings are the usual diagnostic sign. Characteristic crescent-shaped gametocytes may also be observed, though usually later on in infection.

 

falciparum schizont CDC

The stages of maturation of a Plasmodium falciparum schizont. Image courtesy of CDC (www.dpd.cdc.gov)

P. vivax schizonts are large and fill up the entirety of the red blood cell with 12-24 merozoites, each containing visible chromatin and cytoplasm (see below). Their size and shape can differentiate them from the more compact P. ovale and P. malariae schizonts, though separating the former can sometimes be difficult.

vivax schizont CDC

The stages of maturation of a Plasmodium vivax schizont. Image courtesy of CDC (www.dpd.cdc.gov)

Malaria Vaccine

by

QUESTION:

Why is a vaccine against malaria seen as the main hope for the future?

ANSWER:

This answer is courtesy of a medical doctor assisting us with answering your questions.

A vaccine is seen as the great hope for the future because the malaria parasite has an extraordinary talent for developing resistance very rapidly against each class of drug that is introduced into the arsenal against it.  This is accomplished by various mechanisms, such as concentrating and pumping the drug back outside its outer membrane, mutation of drug binding sites rendering the drug molecules incapable of attaching to or entering the cell in order to do its work and alteration of other enzymes within the cell to change the pH  (acidity), again rendering certain drugs ineffective, even if they do get in (among other mechanisms!). That said, the development of an effective vaccine has been difficult due to changing surface proteins against which these vaccines are being developed.  In order to work, the vaccine has to be developed targeting highly “conserved” outer proteins which do not undergo genetic mutation frequently…ie, not so much of a moving target.

 

Clinical malaria, taking chloroquine

by

QUESTION:

Patient having malaria. Taking chloroquine. Then temp becomes normal but headache occurred. What to do?

ANSWER:

One of our collaborating medical doctors kindly assisted in answering this question. She suggests more clinical information is required; what type of malaria is the chloroquine being used for, for example? Also, the headache should not be from the drug, suggesting there is another cause which should be investigated.

Diagnosis of malaria or another condition?

by

QUESTION:

Patient is responding to malaria intravenous medicines but the blood test are not showing any strains of malaria parasites.
Is it possible it is malaria or some other disease?

ANSWER:

I’m afraid it is hard to answer this without more information regarding what steps have been taken to diagnose infection, what medication is being given, and what other clinical information is available. Intravenous medication for malaria is usually quinine or artesunate, and it is unlikely that any medical institution or practitioner would give these unless they had seen malaria on testing, as these agents are generally reserved for severe disease. Another thought is that they are using doxycycline, which is an antibiotice with a broader spectrum of use, and the patient’s improvement is due to the drug taking care of something else other than malaria (Babesia, Bartonella, Borrelia).

Malaria symptoms

by

QUESTION:

What are the symptoms?

ANSWER:

Symptoms of malaria include fever and flu-like illness, including shaking chills, headache, muscle aches, and tiredness. Nausea, vomiting, and diarrhea may also occur. Malaria may cause anemia and jaundice (yellow coloring of the skin and eyes) because of the loss of red blood cells. Symptoms usually appear between 10 and 15 days after the mosquito bite. If not treated, malaria can quickly become life-threatening by disrupting the blood supply to vital organs. Infection with one type of malaria, Plasmodium falciparum, if not promptly treated, may cause kidney failure, seizures, mental confusion, coma, and death. In many parts of the world, the parasites have developed resistance to a number of malaria medicines.

Can malaria cause kidney failure?

by

QUESTION:

Can malaria be a cause for kidney failure or brain fever?

ANSWER:

Malaria, and specifically Plasmodium falciparum malaria, the most severe and deadly form of the disease, can certainly cause both renal failure and brain fever. It usually does this by infecting red blood cells, which then become blocked in tiny blood vessels deep within organs. This process is called sequestration. When sequestration happens in the brain, the effect can be so-called “cerebral malaria” or brain fever. In the kidney, this can result in kidney failure. Given these severe consequences, it is crucially important to seek diagnosis and then treatment immediately if you are concerned you might be suffering from malaria.

What is “Pf” and “Pv” in relation to malaria?

by

QUESTION:

What is pf and pv?

ANSWER:

“Pf” stands for Plasmodium falciparum and “Pv” stands for Plasmodium vivax. These are two different species of the parasite that causes malaria in humans. Pf causes the most acute, severe form of the disease, which can have a cerebral manifestation (“cerebral malaria”) and causes the most deaths worldwide. Pv is still a serious disease, but usually less severe. If diagnosed early, both forms are easily treated and completely curable.