QUESTION
How is malaria a global issue?
ANSWER
Malaria is a global issue because it is found all over the world, with people in 109 countries at everyday risk of infection and approximately 250 million cases every year. In fact, every year, cases of malaria are reported from every continent of the world apart from Antartica; moreover, there are concerns that in the face of climate change, more areas of the world will become suitable for transmission of malaria, making it even more widespread.
QUESTION
Is there any chance of opposing the malarial infection by hormones? If yes,then how is that done?
ANSWER
Malaria incidence is roughly equal between males and females, so it is not believed that sex hormones have any influence of infection rates. However, the progress of infection with respect to hormones has not been extensively studied. It is unlikely that hormonal supplements would have effect in preventing infection.
QUESTION
What are the main symptoms of malaria?
ANSWER
Malaria can have many different symptoms, but the initial signs are similar to a flu-like illness, with high fever, chills, headache and muscle soreness or aches. A characteristic sign of malaria is cyclical fever, with peaks of severity every two or three days. Additionally, some people will experience nausea, coughing, vomiting and/or diarrhea.
Because these symptoms are quite generic of a wide variety of illnesses, if you live in a malaria-endemic region, it is crucial to be tested when you develop such symptoms, rather than assuming it’s just the flu and soldiering on! If you have recently traveled to a malarial area and start to experience these signs of infection, similarly you should inform your doctor of your travel history, as otherwise they might not recognize your symptoms as potentially that of malaria.
If treated rapidly and with the correct medication, malaria is almost always completely treatable; it is only if treatment is delayed that it becomes more serious, with long-lasting and potentially fatal consequences. Similarly, if you take sensible precautions while living or traveling in malarial areas, such as taking prophylaxis (and taking them as per the instructions, for the full required amount of time!), avoiding being bitten by mosquitoes and sleeping under an insecticide-treated bed-net, you vastly reduce your chances of getting infected in the first place.
It’s also worth noting that different species of Plasmodium, the parasite that causes malaria, cause slightly different manifestations of the disease, and also require different forms of treatment. Plasmodium falciparum has a unique way of affecting the red blood cells it infects, which eventually can result in loss of function of internal organs. ‘Cerebral malaria’ is a particularly deadly version of this, whereby the function of the brain is affected. The cycles of fever, mentioned above, are caused by synchronous rupturing of the red blood cells in the body by the malaria parasite; P. falciparum, P. vivax and P. ovale, complete this cycle every 48 hours, resulting in fever cycles of roughly two days (though P. falciparum can be unpredictable); P. malariae, on the other hand, has a cycle lasting 72 hours, so three day cycles of fever are expected. Finally, although many types of malaria can be successfully treated with the drug chloroquine, some strains, and notably of P. falciparum, have become resistant to this treatment. In these cases, artemesinin-based treatment is recommended, usually in combination with other therapies (artemesinin-combination therapy, or ACT). P. vivax, in addition, requires an additional drug, called primaquine, which is used to treat lingering liver stages of the parasite, to prevent recurrence of the infection.
QUESTION
Explain how malaria can cause renal failure?
ANSWER
There are several mechanisms by which malaria can contribute to renal failure, which vary due to the type of malaria. The exact way in which these various effects combine to cause acute renal failure is not known.
The most common type of malaria to cause renal failure is Plasmodium falciparum, generally the most severe and deadly form of the disease. P. falciparum infected red blood cells are known to sequester in tiny red blood cells deep within major organs, including the kidney; it is thought that reduced blood flow and resulting lack of oxygen may contribute to renal failure. Exaggerated immune response to infection may also be a major contributor to renal failure—this is most likely to cause of renal complications seen in other forms of malaria infection, such as Plasmodium malariae infection.
Moreover, acute renal failure is more usually observed in non-immune adults to malaria (such as those who did not grow up in malaria areas) or older children, again suggesting an involvement of the immune response. Finally, dehydration, associated with a lack of sufficient fluid intake during illness with malaria, may compound these other issues, and contribute to renal failure. Perhaps counterintuitively, administration of intravenous fluids may actually worsen the system, due to the body’s shock-like response to the sudden increase in fluids.
QUESTION
Which mosquito causes malaria?
ANSWER
Map of the main global mosquito vectors of malaria (image courtesy of CDC)
It is important to note that mosquitoes do not CAUSE malaria—the disease itself is caused by microscopic, single-celled animals called Plasmodium. These Plasmodium parasites live and reproduce inside the mosquito, and when the mosquito bites a person, the parasites are transferred into that person’s blood via the mosquito’s saliva. If another mosquito bites a person with malaria, they will pick up the parasites from the person’s blood, and the cycle continues.
Malaria parasites are simply transmitted by mosquitoes, and specifically of the genus Anopheles, of which a variety of different species are capable of transmitting it to humans. In Africa, the species most responsible for transmission is An. gambiae, which actually consists of a group of very similar and closely related species; the group as a whole is known as the An. gambiae species complex. An. funestus is also a wide-spread and important vector species in Africa. Below is a map, courtesy of the CDC, which shows the distribution of some of the main malaria vector mosquitoes worldwide.
QUESTION
how can malaria affect our society?
ANSWER
There are many ways in which malaria can potentially affect our society, and particularly people living in highly endemic areas for transmission.
Most obviously, malaria has a huge burden on health services, as sick people require diagnosis, treatment and sometimes hospital care. These days of illness prevent people from going to work or children from going to school, and this can have a knock-on effect on a society’s economy. In fact, somescientists suggest that disease is a key factor “trapping” developing countries into poverty (see Jeffrey Sach’s work on the poverty trap, for example).
High levels of absenteeism from school can hinder efforts to improve literacy rates and stall the progress of education systems. Moreover, since children are one of the highest risk groups for infection with malaria, deaths occur disproportionately in children under the age of 5, contributing significantly to many countries’ high child mortality rates; high child mortality rates often result in high fertility rates, as families seek to replace children lost to disease or other causes. This in turn can lead to a rapidly growing population, which later on can result in a workforce which is larger than the number of available jobs, leading to high youth/young adult unemployment and dissatisfaction.
However, efforts to control malaria, as well as other diseases, have also had positive impacts on many societies, through building clinics for local health care as well as training health workers in the prevention, diagnosis and treatment of the disease. There is currently a huge global push to reduce the burden of malaria, and particularly to eliminate deaths from the disease by 2015, which will have enormous benefits to many societies.
Moreover, the process of international collaboration required for these initiatives can be seen to strengthen relationships between donors and recipient organisations in developing countries; these partnerships create benefits that surpass malaria control efforts alone, as they often have knock-on effects on other aspects of health care and development. As such, while malaria is undoubtedly a huge problem and a negative impact on society, by working together to control this disease the benefits to society may even outweigh the simple health improvements and cause lasting positive change.
QUESTION
For how long does this vaccine work?
ANSWER
There is not yet a commercially available vaccine against malaria. Recently, results were published (in the New England Journal of Medicine – press releases and news reports about the study are available through the main page of www.malaria.com) presenting preliminary findings of the first Phase 3 clinical trial for a vaccine, called RTS,S. The trial will not fully conclude until 2014, and so we won’t know for a few more years exactly how effective it is or for how long. The results that were just published showed only a 50% level of protection against malaria from the vaccine (in African children, most of whom also slept under bednets and generally had access to a high standard of medical care), and that value appeared to decrease over time, with protection levels after a year only about 35%. However, these early findings are still potentially promising, especially for remote areas with low access to other more immediate health care options.
QUESTION
I came back from a Kenya safari and Mombasa beach holiday 21 days ago.
I took my malaria tablets as prescribed, and only got 5 bites on my last morning.
Since yesterday, I have been feeling hot then cold, though not shivering or overly sweating. A headache which is constantly there. I have also today been sick after eating/drinking. Feeling really tired. Also sore throat and blocked nose which makes me think its more a cold, so don’t want to bother my GP.
Any advice would be appreciated.
ANSWER
Malaria does have an incubation period, which means that the symptoms only show up days or weeks (or in some cases, years) after the patient is bitten by an infected mosquito. Different species of malaria have different incubation times; Plasmodium falciparum, which is the most common form in sub-Saharan Africa, usually has shorter incubation times than P. vivax, a still-acute but less deadly form. P. falciparum incubation is usually between 1 and 3 weeks, although taking anti-malarial medication can extend it. As such, since you began experiencing symptoms within a few weeks of returning, there is definitely a chance it could be malaria, although less likely if you haven’t experienced any fever (this is a key symptom of malaria, and usually goes in cycles of about 48 hours). However, since malaria is a serious issue, and can progress rapidly if not treated, I would suggest you see your GP – if you tell them that you have recently returned from a highly malarial area, they will understand your concern! Alternatively, if you live near London, if you have a fever you can go straight to the A&E department of the Hospital for Tropical Diseases (HTD) in Warren Street, where they have doctors that specialise in traveller’s health and tropical medicine.
QUESTION:
Plasmodium falciparum AMA1 was discovered how?
ANSWER:
AMA1 stands for “apical membrane antigen 1”, and it is a protein expressed in the cell membrane of the P. falciparum parasites.
Whereas many of these antigenic proteins are highly variable between parasites, this one appears to be relatively well conserved in evolutionary terms, and therefore is a leading drug target candidate for development of new therapeutic medication against malaria.
The presence of AMA1 was elucidated during the genome sequencing of Plasmodium falciparum, which was completed in 2002; in the same year, mass spectrometry of the proteins present in P. falciparum was also done, shedding light on the exact structure and biochemistry of AMA1. Both of these studies were published in Nature magazine in 2002.
QUESTION
What is chloroquine resistant malaria?
ANSWER
Chloroquine-resistant malaria is exactly what it sounds like—particular types of malaria which are not cured by treatment with chloroquine.
Chloroquine was first discovered in the 1930s in Germany and began to be widely used as an anti-malaria post-World War II, in the late 1940s. However, resistance to the drug also rapidly emerged, with the first cases of Plasmodium falciparum not being cured by administration of chloroquine being reported in the 1950s.
Since then, resistance has spread rapidly (since obviously it is beneficial to the parasite to be resistant, so various mutations conferring this protection have arisen multiple times in different areas in the world and also been passed on preferentially to new generations of malaria parasites), and now chloroquine resistant P. falciparum can be found globally in malaria-endemic areas.
Chloroquine resistance in Plasmodium vivax has also now arisen, though more recently—the first reports came from 1989, in Australia, in travellers returning from Papua New Guinea. Now, chloroquine resistant forms of P. vivax are found in multiple locations in south-east Asia, such as Myanmar and India, as well as from Guyana in South America.
Nowadays, other drugs, and notably ones containing artemisinin-based compounds, are preferentially used to treat uncomplicated malaria and especially in areas where chloroquine resistance is known to occur. However, due to fears of resistance to these compounds also developing, the World Health Organisation recommends that artemisinin-based compounds only be administered in conjunction with other anti-malaria drugs, such as lumefantrine (which in combination with artemether forms the widely-used anti-malarial treatment Coartem). These combinations are known as artemisinin-based combination therapies, or ACTs for short.