By Geoffrey Kamadi
Concerns that the gains made in combating malaria may have plateaued over the last four years, is well captured in the WHO’s World Malaria Report. The report notes that of the 400,000 deaths in 2019 attributed to the disease, 90% occurred in Africa.
And fears that the Covid-19 pandemic could be playing a part in preventing patients from seeking medical care, is disconcerting to say the least.
It is known for instance, that some patients would forego seeking medical attention on the suspicion that they might be exhibiting symptoms associated with Covid-19. This of course precludes them from receiving important malaria intervention at a given health facility.
Test is Affordable
Long regarded as the gold standard test for the presence of malaria parasites in their early stages of development, microscopy is not all that reliable – at least going by recent studies in Kenya.
The techniques basically entails the examination of a drop of blood smear on a microscope slide for the malaria causing parasite.
This study was conducted jointly by the WHO and the Kenya Medical Research Institute (KEMRI) in 2019. It pointed out gaps that may exist when it came to using the microscopy in identifying the malaria parasite.
The clinical study was conducted in the Busia in Western Kenya – a malaria endemic region. The study began in 2016 before concluding in August 2019.
Even so, Protus Omondi, a researcher with KEMRI hastens to clarify that the study looked specifically at the malaria transmission stages.
These are the sexual stages of parasite development, otherwise known as the gametocyte stage, “which are also not usually targeted by the commonly used antimalaria drugs,” says Omondi, who is pursuing his PhD studies in Japan.
As to the question whether microscopy as a technique should be discouraged, given its inadequacies, Omondi says not so fast.
“Microscopy is still the gold standard, or the recommended tool, for detecting malaria parasite in the clinical setting, as it is still accurate and economical in detecting other stages-asexual [of the parasite development] which are usually responsible for malaria symptoms,” he explains.
What make the technique particularly inefficient, is the fact that gametocytes are known to circulate among populations, albeit in very low levels, even after the administration of malaria treatment following a microscopy test.
What this means is that the patient remains a carrier of gametocytes long after treatment. In other words, endemicity of malaria will still exists in a given population.
“We were able to find out that even after treatment, children still carry transmission stages which may facilitate continued transmission in the region after treatment, because mosquitoes are always present in the region,” he explains.
He maintains that when detecting gametocytes, microscopy is not ideal. This is because the technique is not sensitive enough to identify the stages of parasite development, despite the fact that these stages remain are responsible for disease transmission.
It is recommended that gametocyte tests be conducted during treatment.
More Data Needed
On the other hand, drugs that can clear parasite transmission should also be incorporated into the normal regimen to block malaria transmission efficiently, according to Omondi.
What Omondi is talking about is the drug Primaquin, that has direct effect on gametocytes. However, the only limiting factor going the Primaquin route is the absence of enough data, supporting what scientists have been able to observe.
“You need to do more in order to generate data,” he says.
All of the people surveyed in the WHO/ KEMRI clinical study had uncomplicated malaria, 85% percent of whom were found to harbor gametocytes.