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.

Malaria Transmission and Deaths in the United States

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QUESTION

How do you get malaria? How does malaria come to the United States? How many people have died from malaria?

ANSWER

Malaria is caused by infection with single-celled parasites called Plasmodium. There are five different species which infect humans; of these, Plasmodium falciparum is the most deadly. The Plasmodium parasites are transmitted to humans through the bite of an infected female Anopheles mosquito; when these mosquitoes bite a human, they transfer some of the parasites in their saliva.

After undergoing one set of multiplications in the liver, the malaria parasites are released into the blood, where they repeatedly infect and destroy red blood cells, multiplying in the process. These cycles of infection and destruction of red blood cells cause the cyclical fever that is characteristic of malaria. Eventually, the parasite produces new types of cells, called gametocytes; if the patient is then bitten by another mosquito, the mosquito can take up gametocytes as well as blood when it feeds, and the cycle continues.

Malaria used to be relatively common in the United States, though usually only occurring during the summer months and restricted to the warm, wet south-eastern region. However, a concerted control campaign in the 1940s, focusing mainly on vector control (i.e. killing mosquito and reducing their opportunities for breeding) swiftly led to the eradication of malaria from the US.

Nowadays, virtually all malaria cases in the US are imported from abroad, whereby people get infected when traveling to other countries, but are only diagnosed as having malaria when they return home. There are about 1,000 cases of malaria reported each year in the US, and most of these were actually caught outside the US. Very rarely, an Anopheles mosquito will bite one of these travelers once they have returned from abroad, and therefore have the potential to transmit malaria within the US. However, due to a strong public health network and good access to malaria diagnosis and treatment, these events rarely lead to more than a handful of cases before they are quickly treated and transmission eliminated again.

The World Health Organisation estimates that last year, approximately 700,000 people died of malaria. Of these, 90% were in sub-Saharan Africa, and the vast majority were children under the age of 5.

What is malaria, and what causes it?

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QUESTION

What is malaria and what causes it?

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).

Cyclical Fever and Malaria Symptoms

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QUESTION

My dad is not well from last one month. In the evening time he feels headache, neck pain and 102 Temp.

Can you please tell me can it be Malaria.

ANSWER

Those symptoms can be characteristic of malaria—cyclical fever is a key symptom, though usually the cycles are every other day or even every third day (depending on the type of malaria). However, in some cases the cycles are more frequent or the patient may even have constant fever.

One of the difficulties with diagnosing malaria is that its symptoms are very general and can therefore be mistaken for many other illnesses. Likewise, in areas of high malaria transmission, doctors may assume a feverish illness is malaria without thinking about other possible diseases. As such, it is crucial that you take your father for a blood test, which is the only accurate way to diagnose malaria.

The doctor or clinician will either make a blood film and look at it under the microscope, or use a tiny drop of blood in a rapid diagnostic test. Either way, it is important for them to see evidence of a malaria infection before they give your father treatment. The diagnostic test should also show which type of malaria your father has (if indeed he has malaria), and this will also help to determine which is the most appropriate type of medication.

Malaria in Borneo, Indonesia

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QUESTION

We fly to Borneo tomorrow and have been very stupid not thinking about Malaria medication. Can someone quickly tell if I should take medication when there and also what type would be best to take?

Thank you for your help.

ANSWER

Yes! Malaria prophylaxis is recommended for trips to Indonesian Borneo, particularly rural areas. Recommended forms of prophylaxis are Malarone (atovaquone-proguanil), doxycycline and Lariam (mefloquine). The first is the most expensive, but has the fewest side effects, the second is the cheapest but can induce sun sensitivity and needs to be taken for 4 weeks after returning home and the third only requires one pill a week (the others are taken daily) but side effects can be severe and disturbing, including vivid dreams, impaired consciousness and hallucinations.

I am less familiar with south-east Asia, but I know in Africa doxycycline is readily available, for very little money, at local pharmacies. Therefore if you don’t have time to get the necessary anti-malarials before you leave, don’t panic! You may well be able to buy them in-country, particularly if you stop in Jakarta or another major city on your way. Check expiry dates and make sure the drugs are in the original packaging before you purchase though, as counterfeit drugs are distressingly prevalent. Also, do not buy chloroquine (or indeed any anti-malarial not listed above)—malaria in Borneo has been reported to be resistant to chloroquine and so this is not an appropriate anti-malarial for this area.

Please consider sharing your experiences with whichever prophylactic you choose when you return from your trip. We at MALARIA.com are trying to compile data on people’s experiences with malaria prophylactics and treatment medication, and we would be very grateful if you would take our malaria survey. Thank you!

Please also use other preventative measures against malaria while you are in Borneo—sleeping underneath an insecticide-treated bednet and wearing long-sleeved clothing in the evenings and at night, plus applying insect-repellent to exposed skin, can all help to reduce the incidence of mosquito bites and thus the risk of contracting malaria. Plus, avoiding insect bites will probably improve your enjoyment of the trip as a whole!

Malaria Causes

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QUESTION

What are the causes of 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).

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).

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)

Is malaria infectious?

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QUESTION

Is malaria infectious or noninfectious?

ANSWER

Malaria is considered an infectious disease because it can be transmitted from one person to another, via the bite of an infected mosquito. Since the parasite that causes malaria is passed through the blood, it can also be transmitted via organ transplant, blood transfusion, or via pregnancy (so-called “congenital” malaria).