Malaria in KwaZulu Natal

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QUESTION

How many people are infected by malaria in KZN?

ANSWER

By “KNZ” I assume you mean KwaZulu Natal (for the benefit of other readers, this is a region of South Africa, in the north-eastern portion of the country). KZN is one of the few parts of South Africa that experiences malaria transmission, though effective control measures have reduced its impact as a public health threat.

Up until 1996, South African policy had been to use DDT (even though it was a banned substance) to control mosquito populations, and malaria levels had correspondingly been low. However, after cessation of spraying with DDT, the number of malaria cases increased, to a high of over 40,000 cases in the 1999/2000 malaria season (in KZN, malaria is most commonly transmitted during the wet summer months, from November to May). Since then, the use of DDT as an insecticide has been reintroduced (along with other public health measures, such as switching to artemisinin-based combination therapies for first-line malaria treatment), and the burden of malaria has plummeted.

The most recent data I could find reported less than 3500 cases for the 2001/2002 malaria season, and zero cases in 2002/2003 (though the data I found were only up to February 2003). Efforts to coordinate malaria control between South Africa, Mozambique and Swaziland have also contributed to the success of reducing malaria transmission in the region.

Why not create a vaccine for malaria?

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QUESTION

Why not create a vaccine for malaria?

ANSWER

There are many teams of scientists working hard to try to produce a malaria vaccine. In fact, only last year, the preliminary results of a vaccine trial were published. The vaccine, called RTS,S, has been produced by GlaxoSmithKline and is in the midst of Phase III trials in Africa.

The preliminary results showed approximately a 50% reduction in malaria incidence, though it is not clear how much of that protection came from the vaccine and how much should be attributed to the vaccine adjunct (a compound given with the vaccine to boost immune responses). The preliminary results also did not include analysis of how much the vaccine prevented mortality due to malaria, and levels of protection against severe malaria appeared to be low.

However, we will have to wait until 2014 for the full and final results of the clinical trial to be made available. In the meantime, other vaccine candidates are being developed, but there are many challenges to overcome. For example, there are five different types of malaria that infect people: these differ significantly in the way they develop in the human host, and so a vaccine appropriate for one may not be effective against the others.

Most vaccine researchers are focusing on Plasmodium falciparum, the most deadly form of malaria, and a vaccine effective against this parasite would certainly do the most to reduce malaria-related mortality. However, Plasmodium vivax also causes high morbidity, particularly in Asia and the Pacific, and so should not be overlooked. Moreover, within each of these species exist different strains in different areas, each of which can be markedly different from a genetic perspective.

Finally, we do not yet fully understand the complex ways in which our immune system reacts to malaria. As such, this presents a challenge to developing an effective malaria vaccine, though many scientists are willing to address this challenge and have made big inroads in the search for a safe, effective vaccine.

Another stumbling block has been inadequate financial commitment; increased resources devoted towards vaccine development would help overcome the scientific and technical obstacles in our way. PATH, coordinating the Malaria Vaccine Initiative, mentions for example that it can cost up to half a billion dollars ($500,000,000!) to fund a vaccine through the full process of development, testing and clinical trials through to licensing.

Malaria Recurrence and Treatment

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QUESTION

Since September 2011 I had malaria falciparum. The first medication I took was Coartem, after 2 weeks  I had the same symptoms then the test was +1.5 ,i took Coartem again. 2 weeks after the doctor gave me Malarone ,then 19 days it come back . the doc. gave me Quinine -tablets without doxycycline. but no thing change.

Until now each 14-25 days the malaria comes back, I ask my doctor to do any extra test or to do any thing else, but he told me that “I don’t have severe malaria.”  So why all this medication but i still sick??

On 10 feb 2012 I took Artequin. I feel better but after 15 days it came back , then I take Artequin again. I`m confused what to do?
PLEASE HELP!!!

ANSWER

I think I replied to the comment you made on the “Diagnostic Advice” Q&A post – I will copy the response I wrote there below:

It is certainly unusual to have such persistent malaria; usually Coartem cures it very quickly. Where are you obtaining your medication? It could be that the drugs you took were out of date (expired) or counterfeit; this can decrease efficacy and lead to a reduction of symptoms but not a complete cure. Also, what kind of test is your doctor using? If it is a blood smear, you might want to ask if another technician could read the slides, to double-check the diagnosis. I have seen cases elsewhere in Africa where doctors diagnose malaria by default without really examining the blood slide closely. You could try to get a malaria rapid diagnostic test; this looks for specific proteins associated with malaria infection in your blood, and can be more sensitive than blood slides. You can even perform these tests at home, so double check what the doctor tells you.

Otherwise, if you are truly getting re-infected very rapidly, you should look into more effective preventive measures against getting bitten by mosquitoes. This includes sleeping under a long-lasting insecticide treated bednet, wearing long-sleeved clothing at night and in the evenings and applying insecticide to exposed skin.

Malaria and Ross River Fever

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QUESTION

Is malaria similar to Ross river Fever which is common in Australia? If you have Ross River and get bitten by a mosquito can the mosquito pass it on to some one else.

ANSWER

Ross River fever is similar to malaria in that both are transmitted by mosquitoes. However, Ross River fever is caused by a virus, whereas malaria is caused by a protozoan (single-celled) parasite. Also, the type of mosquitoes they use are different. Malaria can only be transmitted by mosquitoes of the genus Anopheles, whereas the Ross River fever virus is usually transmitted by Aedes or Culex mosquitoes.

Another difference is that Ross River virus also infects lots of other mammals, with kangaroos and wallabies key reservoir species in the wild, whereas the species of malaria which infect humans are more or less limited to us (though there have been cases of human malaria infecting closely related animals, such as gorillas and chimpanzees).

As for your other question, as far as I know there is no reason why a mosquito infected with Ross River virus couldn’t bite multiple humans or other mammals, and thus transmit the disease to several new hosts.

Malaria In Africa

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QUESTION

What factors cause Africans to get this disease?

ANSWER

The highest number of malaria cases every year occur in Africa, not because of anything specifically due to the people living there (in fact, they may be better protected against malaria than most—I will come onto this later) but because malaria transmission is very high in many parts of sub-Saharan Africa and sufficient preventative measures are still lacking in some places.

Malaria transmission requires specific environmental criteria, such as sufficient temperature and rainfall. These conditions are met in many countries in Africa, and unlike some other parts of the world, temperatures are suitable year-round for the development of the Anopheles mosquitoes that act as the vector for mosquito, meaning that in some places, transmission can occur throughout the year. In addition, many people do not take appropriate preventative measures against malaria; in some cases, this is due to a lack of means to buy items such as insecticide-treated bednets, and in other cases people have not been educated about the dangers of malaria or how to prevent it, so they do not know what preventative measures they should be undertaking.

Organisations such as the World Health Organisation, the US Agency for International Development, the Global Fund, the Roll Back Malaria consortium and Malaria No More are working to improve both access to preventative measures, such as bednets and indoor residual spraying, while also educating people about the need for prevention and also what to do if they suspect themselves or a family member has malaria. These efforts have already reduced the burden of malaria in Africa; the number of deaths is dropping every year, and they hope to have eliminated deaths from malaria altogether by the year 2015.

I mentioned that Africans may be better protected against malaria naturally—scientists have noted that populations living in areas with high levels of malaria have some genetic protection against infection. One example of this is the Duffy antigen. People who are negative for this gene seem to be protected against Plasmodium vivax and P. knowlesi malaria (it was originally thought they were resistant to infection, but more recent evidence from Kenya suggests in fact they still get infected, but do not get as sick). Another is the gene for sickle cell anaemia; despite causing highly debilitating and even lethal anaemia if both copies of the gene are inherited, a single copy of the gene confers strong resistance against malaria. Both of these genetic traits are highly prevalent in African populations.

In addition, early exposure to malaria results in the acquisition of immunity to infection. This, over time, Africans who survive childhood malaria go on to be less susceptible as adults. The exception to this are pregnant women; in order to support the growing foetus, a pregnant women’s immune system becomes much weaker (otherwise there is a risk of the immune system rejecting the foetus). As such, even if she had high levels of acquired immunity to malaria prior to her pregnancy, once pregnant she becomes much more susceptible. This is particularly true for a woman’s first pregnancy.

What are the symptoms of malaria?

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QUESTION

What are the symptoms of malaria?

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.

Frequent Fever

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QUESTION

I live in Mumbai,India. My mother’s age is 56. She is getting fever from last 1 month and also lost her appetite. We have tested for malaria but it is negative. Tried 4-5 doctors but no one is able to detect the exact cause. She feels better for 3-4 days after medication but then again gets a fever. She feels like vomiting while trying to eat something. Please help.

ANSWER

If the doctors have tested her for malaria and the test was negative, then she probably isn’t suffering from malaria. There are many other potential causes for her illness, from influenza to gastroenteritis. She should try to keep drinking plenty of fluids to stay rehydrated, and plain foods so as not to upset her stomach but keep her strength up. We are not able to give specific medical advice. If she is still feeling sick, you should consult another doctor and ask for a more comprehensive set of tests to determine the cause of illness (including blood tests and a faecal examination to look for parasites).

Malaria in Mosquitoes

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QUESTION

Why can’t mosquitoes become sick of malaria? What do they have in their system that prevent them from becoming sick yet they transmit the disease to humans?

ANSWER

First of all, mosquitoes do get “sick” when infected with malaria, though not in the same way as humans. This is due to the major differences between human and mosquito physiology and also differences in the life stage of the malaria parasite between the different hosts.

Humans get sick from malaria because the malaria parasite, when inside the human host, sequentially infects red blood cells, multiplying inside them and then destroying them. This process of destruction and the resultant debris in the blood results fever and other symptoms (some of which are exacerbated by the body’s immune response).

Mosquitoes are insects, and do not have blood in the same way as humans. Instead, in the mosquito, the malaria parasites differentiate into male and female life stages (called gametocytes) which fuse into the mosquitoes gut. After further reproduction, they eventually produce sporozoites that rupture out of the mosquito gut wall and migrate to the salivary glands, where they can be infected into a new human host.  

Mosquitoes also have a very different immune system to humans, and so the concept of “sick” is not the same for them as for humans. However, there is a lot of evidence that infection with malaria results in reduced reproductive success for the mosquito, as well as lower survival. This could be due to protective responses on the part of the mosquito, but also could be mediated by the malaria parasite, by diverted resources towards its own development that could have been used for mosquito reproduction or survival.

When did malaria start?

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QUESTION

What year did malaria start?

ANSWER

Malaria first emerged as an infection of humans tens of thousands, if not hundreds of thousands, of years ago. The species of malaria that infect humans probably evolved from closely related malaria species that infect macaques (in the case of Plasmodium vivax) and gorillas (in the case of P. falciparum).

The earliest records from human history of malaria come from a Chinese medical parchment almost 5000 years ago, and it is believed the ancient Egyptians also recognised the symptoms of the disease. Written accounts of malaria also occur in ancient Roman and Greek texts, though the true causes of malaria were not discovered until the 19th century.

Malaria Vaccine Research

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QUESTION

Is there any research to produce anti malaria vaccine, if not, why?

ANSWER

There are many teams of scientists working hard to try to produce a malaria vaccine. In fact, only last year, the preliminary results of a vaccine trial were published. The vaccine, called RTS,S, has been produced by GlaxoSmithKline and is in the midst of Phase III trials in Africa. The preliminary results showed approximately a 50% reduction in malaria incidence, though it is not clear how much of that protection came from the vaccine and how much should be attributed to the vaccine adjunct (a compound given with the vaccine to boost immune responses).

The preliminary results also did not include analysis of how much the vaccine prevented mortality due to malaria, and levels of protection against severe malaria appeared to be low. However, we will have to wait until 2014 for the full and final results of the clinical trial to be made available. In the meantime, other vaccine candidates are being developed, but there are many challenges to overcome.

For example, there are five different types of malaria that infect people: these differ significantly in the way they develop in the human host, and so a vaccine appropriate for one may not be effective against the others. Most vaccine researchers are focusing on Plasmodium falciparum, the most deadly form of malaria, and a vaccine effective against this parasite would certainly do the most to reduce malaria-related mortality. However, Plasmodium vivax also causes high morbidity, particularly in Asia and the Pacific, and so should not be overlooked.

Moreover, within each of these species exist different strains in different areas, each of which can be markedly different from a genetic perspective. Finally, we do not yet fully understand the complex ways in which our immune system reacts to malaria. As such, this presents a challenge to developing an effective malaria vaccine, though many scientists are willing to address this challenge and have made big inroads in the search for a safe, effective vaccine. For more information on current efforts to develop a malaria vaccine, please see PATH’s Malaria Vaccine Initiative.