Cambodia is one of the countries in the Greater Mekong Subregion (GMS) where the percentage of Plasmodium vivax (Pv) among all malaria species has significantly increased. From January to May 2020, 91% of all malaria species were Pv, according to Cambodia’s National Centre for Parasitology, Entomology and Malaria Control (CNM).
A single Pv infection can lead to multiple relapses, as the parasite remains dormant in the liver, causing further illness to the individual and fuelling onward transmission, and cannot be affected by artemisinin-based combination therapies (ACTs) or chloroquine – the usual first-line antimalarial drugs. Pv can be cured with therapy known as radical cure, using a class of drugs called 8-aminoquinoline which can eradicate Pv parasites and prevent relapses. In order to undergo the radical cure therapy, it is important to test the patient’s glucose-6-phosphate dehydrogenase (G6PD) enzyme status, because there is a risk of severe haemolysis – breakdown of red blood cells, which can lead to anaemia and other complications – in those with reduced G6PD activity, the most common human enzyme disorder.
Qualitative study on perceptions and acceptability of radical cure and G6PD testing
In order to scale up Pv radical cure nationwide in Cambodia, there was a need to collect data about how best to provide radical cure to G6PD-deficient patients. To reduce the enormous burden of Pv in Cambodia, with funding from the Global Fund, a qualitative study named VIGTARC (Plasmodium vivax G6PD testing and radical cure) was launched in 2018 through the joint efforts of the Centre for Health and Social Development (HSD) with technical assistance support from the London School of Hygiene and Tropical Medicine (LSHTM) together with CNM.
The aim of the project is to produce a model for G6PD testing and radical cure for Pv malaria that is operational, pragmatic, effective and cost-effective across the GMS countries. HSD worked closely with CNM to address the burden of Pv infections and provide radical cure treatment, using G6PD testing and 14-day primaquine treatment.
A new hope for the first minority ethnic female patient to overcome frequent relapse malaria
Miss Chanthavy (not her real name) is a 14-year-old girl who lives in Pu Nhav village of Sen Monorom District, Cambodia. Her family is among the poorest of the poor in the village, and she goes daily to cut wood and plant cassava in the forest with her parents to generate income to support the family.
She was diagnosed with Pv by a village malaria worker (VMW) in 2017. She was treated with a three-day ACT, but she experienced relapses with Pv from time to time. She said, “I always brought the medicine with me during my trip to the farm and forest.”
On 27 November 2021, she felt chills during her stay in the forest, and her parents decided to take her back to the village as soon as possible. The VMW in her village performed a rapid diagnostic test, and she tested positive for Pv again. She was treated with three-day artesunate–mefloquine (ASMQ) and was then referred to the Me Mang health centre to have a G6PD test and radical cure therapy.
As part of patient flow, all Pv patients, identified by VMWs or at health facilities, receive a G6PD test at a health facility. Those Pv patients with normal G6PD results are initiated on a 14-day course of primaquine radical therapy. The first dose is administered by the health facility using directly observed therapy (DOT), and the subsequent dosing is provided by VMWs using DOT.
After being tested at the health centre, she was diagnosed with G6PD status (2.5 U/gHb), which meant she was eligible to enrol in the treatment programme and receive the radical cure therapy. She said, “I had to wait at the health centre for about 30 minutes to get the result from the health care staff on whether I could be treated with radical cure. I was called about three times a day for my treatment, and I was often directly observed at my home by HSD staff, VMW and health centre staff.”
Now, Miss Chanthavy has completed the treatment course and is better. She was the first ethnic minority (Pnong) female with Pv to be treated with the primaquine eight-week regimen. Her parents are happy that she will no longer have relapses of malaria. She plans to go back to work on the cassava farm to earn income for the family.
To date, more than 600 patients have received a G6PD test and completed a course of primaquine. The project was researched under RAI2E and was extended up to June 2022. It has shown that the model of care is feasible and acceptable in this setting. This is a major step in the efforts to eliminate malaria in Cambodia by 2025 and prevent infected individuals suffering a lifetime of recurrent relapses.
