icddr,b contributes to lowering regional and global burden of Malaria

Muhammad Zahir Hassan Nabil

Malaria rates have significantly dropped in Bangladesh’s endemic regions, shows an icddr,b study and that people have become more aware about preventing the disease.

Recent surveys have found that malaria prevalence in all endemic districts including the Chittagong Hill Tracts (CHT) declined from 40 to less than 2 people per 1000 population, highlights the study published in Malaria Journal.

Using bed nets is one of the best ways to prevent Malaria. Photo: GMB Akash / icddr,b

This great success demonstrates the impact of two rounds of the Global Fund to Fight AIDS, Tuberculosis and Malaria (GFATM) - funded interventions in 2007 and 2009.

The latest findings also show that people became more aware of the signs and symptoms of malaria, and were more acquainted to using bed nets for prevention of the disease transmitted by mosquitos.


Hidden challenges to eliminate Malaria

Malaria is endemic in 13 of 64 districts in Bangladesh, putting as many as 11 million people at risk of infection.

The Chittagong Hill Tracts (CHT) is in southeastern Bangladesh. Photo: Wasif A Khan / icddr,b

The vast majority of these cases are attributable to the malaria-causing microbe Plasmodium falciparum (P. falciparum). Some of these cases show no symptoms, although the onset of malaria often comes with common symptom such as fever or chills.

“Patients with cases as such act as hidden reservoirs of P. falciparum infections,” says icddr,b scientist Dr Wasif Ali Khan, who spearheads malaria research and represents icddr,b at the Asia Pacific Malaria Elimination Network (APMEN).

A study with icddr,b, funded by the Johns Hopkins Malaria Research Institute (JHMRI), has investigated these asymptomatic cases and found that males, pregnant women, jhum cultivators, and those living closer to forests and at higher elevations at the CHT had a higher prevalence of asymptomatic malaria, according to the findings published in International Journal of Infectious Diseases.

The CHT people do 'Jhum' or 'slash-and-burn' cultivation. Photo: Pierre Prakash / EU-ECHO. CC BY-SA 2.0

“These patients contribute to continued transmission of the disease, which is a major obstruction to eliminating malaria,” says Dr Khan, adding that these findings will help future studies to pinpoint the hidden reservoirs.

Supported by the Swiss Academy of Medical Science (SAMS) and Velux Foundation, another icddr,b study in the American Journal of Tropical Medicine and Hygiene (AJTMH) has determined the nature of infections caused by multiple P. falciparum genetic variants circulating in Bangladesh.

“Malaria is not less-endemic as many might have thought earlier before this first comprehensive report and there may be a good number of asymptomatic infection persisting in the endemic community,” says Dr Mohammad Shafiul Alam, associate scientist at icddr,b and principal investigator of the study.


Navigating safe and effective cure

Despite lower prevalence than the P. falciparum, a more enduring malaria variant called Plasmodium vivax (P. vivax) has added itself to the list of challenges to malaria eradication. P. vivax has the ability to develop drug resistance and thus it remains dormant in the human body and revives to affect the patient after as long as a year,” explains Dr Khan.

The Anopholes mosquito that transmits malaria. Photo: Wellcome Trust. CC BY 4.0

The most recent annual meeting of the APMEN Vivax Working Group in late 2016 has identified one of the major challenges to malaria elimination from the Asia-Pacific by 2030 is the delivery of safe and effective radical cures for P. vivax, notes a report published in the Malaria Journal.

According to the World Health Organization (WHO) recommendations, patients with uncomplicated malaria are treated with the drugs chloroquine and primaquine, the latter particularly aimed at P. vivax infections. “However, patients who are deficient in a natural enzyme called glucose-6-phosphate dehydrogenase (G6PD), develop health complications when treated with primaquine,” says Dr Khan.

Hence it is extremely important to determine to what extent people in malaria endemic areas are G6PD deficient before patients with P. vivax are treated with anti-malaria drugs, as highlighted by the APMEN report.

Published in PLOS One this year, a study with icddr,b evaluated the most efficient G6PD diagnostics tool in resource-poor settings to diagnose G6PD deficiency in the CHT. Another recent icddr,b study, also published in PLOS One, found low G6PD deficiency in CHT and confirmed the safe continuation of national treatment guidelines.

Journal publications on malaria by icddr,b researchers. Graphs: M Shafiqul Alam / icddr,b

In the last 12 years, icddr,b researchers have published around 56 articles in peer-reviewed journals in the field of malaria. The team of scientists working on malaria research remains committed to supporting regional efforts to eliminate malaria in line with global guidelines.


New compound for combating drug-resistant malaria?

The WHO-recommended anti-malaria drug artemisinin for the most virulent P. falciparum malaria has substantially reduced global malaria burden. However, the mutating P. falciparum and its resistance to artemisinin is a cause for concern which threatens the recent gains.

In a recent publication in the New England Journal of Medicine (NEJM), Dr Khan and Dr Alam from icddr,b are among the first researchers to show that artemisinin-resistance is confined to Southeast Asia for the moment. The findings are an outcome of the first global mapping of artemisinin resistance (the KARMA study) led by Institut Pasteur.

“These findings are significant and will pave way for global efforts to eliminate malaria to meet the stipulated target,” anticipates Dr Khan.

A researcher at a icddr,b lab. Photo: M Shafiqul Alam / icddr,b

At icddr,b, Dr Alam and his team are now exploring new anti-malarial components in medicinal plants from Bangladesh. Some of the plant extracts under examination have shown significant anti-malaria activity against particular malaria strains. “We are working to isolate the pure compound, which could be a novel anti-malaria compound,” says Dr Alam.

The research is being carried out with Bangladesh’s first-ever in vitro P. flaciparum culture facility, established at icddr,b with support from Sida, one of the core donors of icddr,b.