Researchers ID Key Antibodies in Kenyans with Malaria Immunity

August 3, 2012 by Malaria.com

Australian scientists say they have made an important discovery in the fight against malaria. They have found that people in Africa who are immune to malaria have developed powerful natural defenses against the disease.

Researchers at Melbourne’s Burnet Institutewho are searching for ways to develop a vaccine believe that people in east Africa could help unlock some of the secrets of this unremitting disease.

The scientists are investigating why some Kenyans have become immune to malaria. They have identified antibodies, which are part of the body’s natural defenses, that attack the malaria parasite. The hope is that a vaccine can be developed to recreate this natural immunity. Professor James Beeson, a public health physician at the Burnet Institute, says it is an important breakthrough.

“What we know is that some people who develop malaria and recover, develop an immune response that seems to then protect them against, you know, subsequent infections or attacks,” he said. “So the big question has been how does the immune system do this? What specific part of the malaria organism parasite does the immune system attack? And if we know this, could we use this knowledge to develop a vaccine?”

Malaria causes about one million deaths every year, many of them children under the age of five. The mosquito-born disease is present in 90 countries across Africa, South America and Asia. It also prevalent in the South Pacific nations of Papua New Guinea, the Solomon Islands and Vanuatu. Australian researchers believe that an effective vaccine could be available within the next decade.

Source: VOA News

Malaria Treatment with Fansidar

June 13, 2012 by Malaria Q&A

QUESTION

My husband has Malaria following a trip to Kenya and has had a fever for three days. We are in Russia and the only drug available at the pharmacy was Fansidar (we also have some Doxcycyclin). He took three Fansidar tablets last night and feels better but the fever has still not completely gone. What should we do? Take more Fansidar? Thanks for your help.

ANSWER

A single dose of three tablets is the correct amount for an adult over 45kg in weight—do not take any more. Unfortunately, Fansidar is not recommended as the first-line drug against malaria any more since many strains of P. falciparum (the most dangerous type of malaria, and the most common type in Kenya) now have resistance to Fansidar. This could be one reason why the treatment is not fully successful, though it could also be that the treatment has worked, but it will take a day or two more before your husband fully recovers.

Make sure your husband takes in plenty of fluids, and anti-inflammatory drugs such as ibuprofen might help with the fever and any aches he could also be suffering from.

If your husband is still feeling sick after a few days, you should try to have another blood test to see if the malaria parasites are still present in his blood. If you, you should try to find an artemisinin-based combination therapy, such as Coartem, Duo-Cotecxin or Alu. These are the most effective medications against malaria that are currently available, and are recommended as first-line treatment by the World Health Organization (for uncomplicated malaria).

Malaria Deaths by Country

March 16, 2012 by Malaria Q&A

QUESTION

Where are the most deaths of malaria?

ANSWER

Over 90% of the deaths from malaria occur in sub-Saharan Africa, and in children under the age of five. According to the World Health Organisation’s 2011 World Malaria Report, the countries with the five highest numbers of reported malaria deaths for 2010 are (and number of reported deaths): Kenya (26,017 deaths), Democratic Republic of Congo (23,476), Tanzania (15,867), Burkina Faso (9,024) and Uganda (8,431).

However, it is important to note that this indicates the number of reported deaths that were confirmed as malaria; there are other countries in Africa which may have similar levels of malaria mortality but insufficient health infrastructure for accurate diagnosis of cause of death or reporting. Even in countries where reporting levels are high, causes of death are not always accurately determined.

Geographic Range of Malaria

March 13, 2012 by Malaria Q&A

QUESTION

Has the geographic range of malaria increased over the past 20 – 30 years? I have read that preventative measures have helped lower rates of infection, but I’m interested in the extension of the range itself.

ANSWER

That is a very interesting question, and one that garners quite a lot of debate. Preventative measures have actually also helped to limit the range of malaria globally. For example, malaria used to be relatively common in the Mediterranean basin and south-eastern United States, but control measures (mainly based around killing mosquitoes and removing suitable mosquito habitat) has largely eradicated malaria from these areas.

However, there is concern that on-going and future climate change has and will change the distribution of malaria globally. For example, some predictions have suggested that malaria might be able to re-establish itself in the Mediterranean and Middle East, due to higher rainfall and higher winter minimums of temperature. Additionally, malaria may be able to spread to higher altitudes in areas where it is already present at low elevations. This is of huge concern in places like Kenya: Nairobi, the capital city (with around 5million people), sits at 1660 m altitude, and as such currently has generally negligible levels of malaria transmission. However, if climate change enables malaria to move up to this altitude, a huge number of people will be at additional risk of infection. Worryingly, there is some evidence from the Kenyan highlands that these changes are already underway.

Having said this, there are also parts of the world which might see malaria transmission ease as a result of climate change. This is particularly the case where rainfall is expected to decrease, or change significantly in relation to temperature. Moreover, some scientists think that on-going control efforts, particularly with respect to the distribution of bednets, vector control and greater coverage of diagnosis and treatment will continue to reduce the geographical spread of malaria over and beyond the changes associated with climate change. These scientists have compiled a map of Plasmodium falciparum transmission now as compared to data from before control interventions were rolled out—the reduction of transmission risk in many parts of the world, are clear to see (see below).

Maps showing changes in transmission risk and endemicity of Plasmodium falciparum malaria between approximately 1900 (a) and now (b). (c) shows the balance of change in malaria transmission between the two time periods: the higher the negative number, the greater the reduction in malaria transmission. A positive number indicates increased malaria transmission. The different classes of malaria transmission risk are as follows: hypoendemic, prevalence < 10%; mesoendemic, PR ≥ 10% and < 50%; hyperendemic, prevalence ≥ 50% and < 75%; holoendemic, prevalence ≥ 75%. Image reproduced here from Gething et al., (2010), 'Climate change and the global malaria recession', in Nature, volume 465, pages 342-345.

Thalassaemia and Malaria

March 1, 2012 by Malaria Q&A

QUESTION

How can Thalassaemia effect Malaria infection?

ANSWER

Thalassaemia is the name given to a group of inherited genetic blood disorders, which result in reduced or no synthesis of one of the globin protein chains that combine to make haemaglobin. Haemaglobin is used to carry oxygen throughout the body and to its organs.

Thalassaemia can result in anaemia; in some cases, this is severe enough to require periodic blood transfusions. There has long been a hypothesis that thalassaemia might have persisted due to conveying protection against malaria infection; this was suggested due to the geographical distributions of populations with high prevalence of the alleles (gene types) that cause thalassaemia and areas with high levels of malaria transmission. However, scientifically confirming this association has proved challenging.

A recent study from Kenya demonstrated that children with either one copy of the thalassaemia allele or two copies appeared to have a reduced incidence of severe malaria, fewer deaths from malaria and were hospitalized less frequently for malaria. However, they were just as likely as non-thalassaemic children to have mild or sub-clinical malaria, and the same levels of parasitaemia (numbers of parasites in the blood).

A contrasting study from Vanuatu observed higher incidences of severe malaria in children with thalassaemia, though one potential confounding factor in comparing these studies is that the Vanuatu study looked at both P. falciparum and P. vivax, whereas the Kenya study only looked at P. falciparum malaria.

The difference is significant: one of the proposed mechanisms by which thalassaemia protects against malaria is by preventing modification of the surface of red blood cells, which causes the red blood cells to become “sticky” and sequester within the blood vessels that feed major organs, eventually restricting blood flow and causing major complications. This sequestration is only observed to occur during infection with P. falciparum, and so thalassaemia might not be as protective against other forms of malaria. More empirical research from the field is needed to understand the mechanisms relating malaria infection with thalassaemia more fully.

Will Malaria Test Work with No Symptoms Present?

December 23, 2011 by Malaria Q&A

QUESTION

I believe my fiance who lives in Kenya has malaria but refuses to go for a test. She has headaches and now flu like symptoms. I am returning in late December, if the symptoms have gone can I still take her for a blood test to see if malaria is still present even if the symptoms subside?

ANSWER

Most malaria diagnosis in Kenya is done by looking at a small sample of the patient’s blood under the microscope. Unfortunately, using this method, it is almost impossible to detect malaria that is non-symptomatic. In this case, one option would be to use a rapid diagnostic test which looks for antibodies in the blood against malaria – as these antibodies can sometimes persist after the infection has subsided, it can sometimes tell you whether that person recently had malaria. These rapid diagnostic tests are available in most of the main cities in Kenya, in larger pharmacies, and maybe even in some big supermarkets like Nakumatt. However, given how rapidly malaria can progress and how serious is can become, I would highly recommend that your girlfriend goes to a clinic or doctor and has a malaria test! That way she can receive treatment early, before her symptoms get worse.

Blood Test After Child’s Malaria Exposure

November 23, 2011 by Malaria Q&A

QUESTION

Our 2 year old son was exposed and bitten about 10 times on Friday, 21st of Ocober in Malindi, Kenya. This was our last day in Kenya after 3 days on the coast preceded by 4 in Masai Mara. On October 28, our son started vomiting. This lasted a day. He did not have a fever at the time. The doctor diagnosed him with rota virus. Our 2 year old took his last dose of Malarone on the same day the vomiting started.

We believe he did not keep it down. Since the doctor visit our son has developed a cough and has had a low constant 38 C fever for a day and a half. Given the risk of a small child to malaria, is there any reason we should not request a blood test for Malaria?

ANSWER

Generally speaking, coughing is not a common symptom of malaria, and fever more usually comes in cycles, so the clinical presentation suggests that your son may be suffering from another illness.

However, as you say, small children are particularly at risk from malaria, so I would say it is worth getting a blood test for malaria, to be on the safe side. It only requires fingerprick blood, and the results can be available very quickly.

It is also important to remember that Malarone (including Malarone Paediatric, the version marketing for children over 11kg in weight) should be taken for 7 days AFTER leaving a malarial area, to prevent latent stages of malaria developing into a full infection.

With small children, other preventative measures are also especially important, such as sleeping under an insecticide-treated bednet, wearing long sleeved clothing in the evenings and early mornings and using insect repellent on exposed skin.

Objective: To investigate the effect of helminth and/or malaria infection on the risk of HIV infection in pregnant women and its transmission to their offspring.

Design: A retrospective cohort study of pregnant Kenyan women and their offspring from term, uncomplicated vaginal deliveries (n = 936) with a nested case-control study.

Methods: We determined the presence of HIV, malaria, schistosomiasis, lymphatic filariasis, and intestinal helminthes in mothers and tested for HIV antibodies in 12-24 month-old offspring of HIV-positive women. We related these findings to the presence of cord blood lymphocyte activation and cytokine production in response to helminth antigens.

Results: HIV-positive women (n = 83, 8.9% of all women tested) were 2-fold more likely to have peripheral blood and/or placental malaria (P < 0.025) and a 2.1-fold greater likelihood of lymphatic filariasis infection (P < 0.001) compared to location-and-parity matched HIV-negative women. Women with HIV and malaria tended to show an increased risk for mother-to-child-transmission (MTCT) of HIV, although this difference was not significant. MTCT of HIV, however, was significantly higher in women co-infected with one or more helminthes (48%) verses women without helminth infections (10%, P < 0.01; adjusted odds ratio, 7.3; 95% confidence interval, 2.4-33.7). This increased risk for MTCT of HIV correlated with cord blood lymphocytes production of interleukin-5/interleukin-13 in response to helminth antigens (P < 0.001).

Conclusion: Helminth co-infection is associated with increased risk for MTCT of HIV, possibly by a mechanism in which parasite antigens activates lymphocytes in utero. Treatment of helminthic infections during pregnancy may reduce the risk of MTCT of HIV.

Author Information

Gallagher, Maureena; Malhotra, Indua; Mungai, Peter La,b; Wamachi, Alex Nc; Kioko, John Mb; Ouma, John Hd; Muchiri, Ericb; King, Christopher La,e

From the ^aCenter for Global Health and Diseases and Center for AIDS Research, Case Western Reserve University, Cleveland, OH, USA

^bDivision of Vector Borne Diseases, Nairobi, Kenya

^cKenyan Medical Research Institute, Kenya

^dMaseno University, Maseno, Kenya

^eDepartment of Veteran’s Affairs Medical Center, Cleveland, OH, USA.

Correspondence to C. L. King, Center for Global Health and Diseases, Case Western Reserve University, 2103 Cornell Rd, WRB Rm 4132, Cleveland, OH 44106-7286, USA. Tel: +1 216 368 4817; fax: +1 216 368 4825; e-mail: christopher.king@case.edu

Citation: AIDS: Official Journal of the International AIDS Society, Nov. 4, 2005, – Volume 19 – Issue 16 – p 1849-1855

More information: Full text – The Effects of Maternal Helminth and Malaria Infections on Mother-to-Child HIV Transmission (PDF)