In the past few years, the malaria situation worldwide, in general, as well as in Viet Nam specifically, has significantly improved, reflected by the continuous reduction in annual morbidity and mortality. The fight against malaria has gone through multiple phases, with various control strategies. In 2011, the Government of Viet Nam officially approved the "National Strategy for Malaria Control and Elimination in the period 2011-2020 and orientation to 2030". This decision also set specific targets with different action programs, aiming at no province to be in the advanced malaria control phase by 2020 and malaria elimination for the whole country by 2030.

Current guidelines for malaria elimination mostly rely o­n the concept "malaria transmission", which is heterogeneous in elimination localities. Therefore, in this elimination phase, all areas with a higher incidence of malaria should be targeted with interventions until o­nly a few sporadic malaria cases remain in these areas. Heterogeneity of malaria transmission across localities has existed for a long time before they entered the pre-elimination phase, and the identification and targeting of malaria "hotspots" (geographically limited areas with increased transmission and asymptomatic parasite carriage) are key to efficient elimination efforts. Shifting the focus from control to elimination may alter priorities regarding vector control, treatment, and prevention. Furthermore, aggressive elimination efforts may not yield equally favorable results in all areas due to various factors. While keeping case numbers low may be relatively easier, achieving complete elimination with no more indigenous malaria cases may prove challenging in endemic areas. Therefore, malaria elimination necessitates continuous and long-term investments and appropriate interventions, especially in regions with hyperendemicity and a persistent malaria burden at present.

To achieve malaria elimination at different levels, ultimately nationwide, there are numerous challenges that need to be addressed. These challenges must be identified and resolved at the local and regional levels. Generally, the main challenges can be grouped into two categories. The first category consists of ecological risk factors resulting in transmission of malaria in localities, the second o­ne related to the capacity of the malaria elimination system.

When it comes to the risk of malaria transmission, the fewer the malaria transmission factors, the greater the local ability to eliminate malaria. Thus, it can be observed that the factors transmitting malaria are crucial prerequisites for determining the feasibility of malaria elimination. Consequently, the mandatory criterion to be met for verification of malaria-free status, which is set by WHO and required in Viet Nam, includes no indigenous malaria parasites recorded in the area for at least the past 3 consecutive years. At present, there are some factors that may have a greater influence o­n the risk of malaria, with vectors and humans being the primary contributors to malaria transmission in the natural environment. The following is an analysis of some key factors that hinder Vietnam's pursuit of malaria elimination.

Figure 1. Investigation at a malaria focus in Ha Dong commune, Dak Doa district, Gia Lai province

+ Insecticide resistant mosquitoes

Only a few types of insecticides have been approved for use in vector control activities, via twomain vector control interventions namely insecticide-treated nets (ITNs/LLINs) and indoor residual spraying (IRS). Thanks to these measures, the burden of the disease has significantly decreased in recent years. Currently, pyrethroids are the o­nly class of insecticides used in bed-net impregnation for mosquito control.

The resistance of Anopheles vectors to insecticides is increasing and spreading to new areas. Insecticide resistance in malaria vectors has been observed in Africa and Southeast Asia, and gradually spread to parts of the Americas. Similarly, in many countries, the level of insecticide susceptibility has decreased over the years, and suspected insecticide resistance in different vector species has been documented. The effectiveness of insecticides is reduced, jeopardizing the vector control and facilitating the transmission of malaria.

+ Anti-malarial drug resistance and treatment

One of the challenges that cannot be ignored is the antimalarial-drug resistance. The widespread and serious multidrug resistance of P. falciparum worldwide poses a technical barrier to selecting drugs for the treatment of malaria today. Viet Nam shares a border with Cambodia, where P. falciparum has developed high resistance to chloroquine, fansidar, mefloquine, and reduced responsiveness to many currently used drugs, including artemisinin-based combination therapies (ACTs). In Viet Nam, drug-resistant P. falciparum has been identified in six different localities nationwide, including Binh Phuoc, Dak Nong, Gia Lai, Quang Nam, Khanh Hoa, and most recently in 2019, Dak Lak province was also confirmed this status by the World Health Organization (WHO).

Radical treatment and containment of malaria transmission and recurrence are difficult and challenging issues in the fight against malaria. Currently, according to the treatment guidelines of the Ministry of Health (2020), Primaquine is used for the treatment of dormant liver forms (hypnozoites) of P. vivax with a 14-day regimen [3]. Radical treatment of P.vivax malaria is difficult to achieve due to poor compliance with long route of Primaquine administration in spite of its high efficacy. In addition, Primaquine is contraindicated in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency, pregnant women and children under 6 months of age. Testing for G6PD deficiency, in general, is not feasible at primary care settings, where patients would initially seek treatment.

P. vivax also exhibits some distinct biological characteristics, particularly the timing of appearance of its unique sexual stages (gametocytes) in a patient's blood is earlier than that of P. falciparum. Consequently, many patients have a sufficient number of gametocytes to permit disease transmission before the disease is diagnosed or treated.

+ Challenges related to population

Community-based malaria control is very important, so community-related factors greatly affect the effectiveness of current malaria control and elimination program. The burden of malaria is generally greater among mobile populations, free migrants, ethnic minorities and other hard-to-reach populations in remote or inaccessible areas. These population groups stand out as key priorities for local malaria control plans. Specifically, o­ne of the population groups at the highest risk of contracting malaria and contributing to its resurgence is those who engage in forest activities. Evidence from various localities such as Krong Pa (Gia Lai), Ea Kar, Krong Nang (Dak Lak), Song Hinh (Phu Yen) indicates multiple malaria outbreaks is mainly attributed to this particular group. In addition, ensuring accessibility to and prioritizing malaria vector control activities (including ITNs/LLINs and IRS) for these high-risk community groups is considered a crucial step to accelerate malaria elimination in localities.

Some evaluations have shown that the effectiveness of antimalarial measures greatly depends o­n the community's understanding and beliefs about malaria as well as their engagement in these malaria control activities. Research by Gryseels et al. has shown that, in order to achieve further reduction in malaria, in addition to routine anti-malarial measures, it's necessary to comprehend the impact of these measures at the lowest community level and optimize this community's engagement. Beliefs about malaria vary among different communities based o­n education, society, culture, and religion. These factors can affect malaria control and treatment and even activities related to malaria elimination in the community. Therefore, malaria control and elimination programs need to consider the community's social context and cultural practices to enhance their effectiveness.

Migration is presently another matter of concern. It can be seen that, along with the socio-economic development, there are an increasing tendency for people to move and travel. This greatly affects the current malaria control, especially in the context that localities are moving towards malaria elimination. The increased movement of people, especially from malaria-endemic areas to malaria-free areas, will increase the risk of malaria resurgence to these localities, posing a significant challenge to malaria elimination target. Specifically, in malaria elimination, this group of patients is classified as imported cases.

In the past few years, the incidence of imported P. falciparum malaria cases in China originating from African countries has been o­n the rise, attributed to China's enhancement of investments in and tourism to African nations. A systematic analysis by Lai et al aimed to evaluate the driving factors related to the spread of imported P. falciparum malaria from Africa to China, as well as the mortality rate. The research findings revealed that during the period from 2011 to 2015, around 8,653 cases of imported P. falciparum malaria (including 98 fatalities) originating from sub-Saharan countries had entered China.

The early detection, treatment, and management of these imported malaria cases are crucial to limit the re-transmission of malaria. Therefore, a robust malaria case surveillance system is imperative for areas free from malaria. Additionally, analyzing the country-specific movement patterns of malaria cases is of great importance.

+ Capacity of the health system to eliminate malaria

According to the World Health Organization (WHO), surveillance is considered as a key intervention in malaria elimination. Thus, the role of the healthcare system during this phase is highly crucial. And also according to WHO, besides the criterion of no more indigenous malaria case, a strong surveillance system is also required. To eliminate malaria, a robust surveillance system must be in place and operational across all levels of healthcare to prevent reintroduction of local malaria transmission in elimination areas. The surveillance system must be fully functional, especially in terms of services of disease treatment, prevention and epidemiological surveillance to ensure nationwide coverage.

Factors related to the capacity of the healthcare system can be considered in two main groups: technical capacity and resource capacity. Technical capacity encompasses factors that are likely to affect malaria elimination roadmaps in localities, including (i) data management, (ii) intervention activity planning, (iii) inspection, (iv) monitoring and evaluation, and (v) control of imported cases. To address technical capacity issues, the most effective approach is to enhance and improve training, retraining, or technical practice within relevant institutions, units, and healthcare staff engaging in the malaria control and elimination system, especially at the grassroots healthcare level, such as communes and villages. Additionally, focusing o­n high-risk groups such as forest workers and mobile migrant populations is essential.

Figure 2. Approaching the mobile population in Ia Dreh commune, Krong Pa district, Gia Lai province

The group of resource capacity factors includes (i) organizational management, (ii) monitoring systems, (iii) mobilization, and (iv) finances. In localities where were previously stratified as hyper-endemic malaria areas, more resources may have been invested to sustain essential malaria control activities. However, the prevalence of malaria decreases dramatically as entering the elimination phase. If the disease burden is no longer high, it can be seen that mobilizing resources for malaria control activities during this period, especially maintaining stable resources over an extended period becomes challenging.

Overall, the key challenges within the healthcare system that hinder the progress of current malaria control and elimination programmes include weak surveillance capacity and systems, limited human resources, inadequate funding, and weak technical capacity. Financial constraints and technical capacity limitations have led to delays in the malaria elimination roadmap in the Solomon Islands and Vanuatu compared to the planned timeframe. In Papua New Guinea, the national revenue has been severely affected by the global decline in oil and gas prices, which is expected to exert pressure o­n government investments in social sectors such as healthcare and education.

References

Other news »

---

• Viet Nam experiences surge in malaria cases in early 2024 (05/17/2024)
• Hue Central Hospital provides treatment for malaria patient back from Angola (03/14/2024)
• Conference on the summing-up of malaria control and elimination in Central Vietnam in 2023, and Announcement Ceremony of the decision on recognizing the achievement of malaria elimination criteria for Quang Ngai province (01/02/2024)
• Status of Anopheles vectors at malaria increasing sites in Khanh Vinh district, Khanh Hoa province in 2023_Part 2 (08/15/2023)
• Status of Anopheles vectors at malaria increasing sites in Khanh Vinh district, Khanh Hoa province in 2023_Part 1 (08/14/2023)