Increased prevalence of pfdhfr and pfdhps mutations associated with sulfadoxine-pyrimethamine resistance in Plasmodium falciparum isolates from Jazan Region, Southwestern Saudi Arabia: important implications for malaria treatment policy

Malaria during COVID-19 Travel Restrictions in Makkah, Saudi Arabia

Malaria is a parasitic infection that may result in an acute, life-threatening illness. It is a major public health problem in the tropical world. The disease is caused by the parasites of the genus Plasmodium and is transmitted by female Anopheles mosquitoes. Saudi Arabia is in the elimination phase of malaria control. Several parts of Saudi Arabia report cases of imported malaria among travelers and visitors. The city of Makkah in Saudi Arabia has a population of about 2.3 million. Moreover, over 6 million religious visitors from different parts of the world visit Makkah annually. During the COVID-19 outbreak, travel restrictions were enforced in Makkah to contain the spread of COVID-19. We compare the total reported cases of malaria in Makkah before, during, and after COVID-19 travel restrictions in this retrospective cross-sectional study. Data on demographics, clinical data, and laboratory parameters were collected from the medical records of the Ministry of Health, Saudi Arabia. The annual malaria incidence rates in Makkah were 29.13/million people (2018), 37.82/million people (2019), 15.65/million people (2020), 12.61/million people (2021), and 48.69/million people (2022). Most of the malaria cases in Makkah were caused by Plasmodium falciparum, followed by P. vivax. Sudan, Nigeria, Yamen, Pakistan, and India are the top five countries contributing to malaria cases in Makkah. Weekly malaria case analyses revealed that COVID-19-related travel restrictions resulted in zero malaria cases in Makkah, indicating the magnitude of the travel-related malaria burden in the city.

Prevalence of Plasmodium species in Badr Governorate, Madinah Province, Saudi Arabia using microscopy and rapid diagnostic test

Malaria infection still represents a notable public health risk in Saudi Arabia. This cross-sectional study aimed to determine the prevalence of Plasmodium species among clinically suspected cases who presented at Badr General Hospital and healthcare facilities in selected regions of Badr Governorate, Madinah Province, Saudi Arabia between January 2021 and January 2022. A total of 493 suspected patients were recruited from Badr Governorate, investigated for malaria infection using CBFME and rapid diagnostic test- CareStart Malaria Pf/PAN (HRP2/pLDH) Ag Combo rapid diagnostic tests. The results showed that malaria infection was 34 (6.89%) cases among 493 suspected patients using microscopic examination as reference test. Moreover, subjects aged 31 to 40 years and those aged 51 to 60 years had the highest (50%) and lowest (8.82%) percentages of malaria cases. Plasmodium vivax (19/34, 55.88%) was higher than P falciparum (15/34, 44.1%) as the causative agents of malaria cases. The majority of malaria cases (29/34, 80.9%) among non-Saudi mainly from Sudan (15/34, 44.1%), Pakistan (5/34, 14.7%), Bangladesh (5/34, 14.7%) and India (4/34, 11.76%) whereas malaria cases among Saudis (5/34, 14.7%). In addition, the majority of malaria cases (32/34, 94.11%) among male subjects while (2/34, 5.88%) among females. The current study revealed that malaria transmission is still active in Badr Governorate, Madinah Province, Saudi Arabia and represents a public health concern. Further screening implements and continuous epidemiological monitor of the status of malaria infection in Kingdom of Saudi Arabia are thus warranted to improve its controlling activities and eradicate malaria endemicity in the country.

Antimalarial drug efficacy and resistance in malaria-endemic countries in HANMAT-PIAM_net countries of the Eastern Mediterranean Region 2016-2020: Clinical and genetic studies

INTRODUCTION

The World Health Organization recommends regular monitoring of the efficacy of nationally recommended antimalarial drugs. We present the results of studies on the efficacy of recommended antimalarials and molecular markers of artemisinin and partner resistance in Afghanistan, Pakistan, Somalia, Sudan and Yemen.

METHODS

Single-arm prospective studies were conducted to evaluate the efficacy of artesunate-sulfadoxine-pyrimethamine (ASSP) in Afghanistan and Pakistan, artemether-lumefantrine (AL) in all countries, or dihydroartemisinin-piperaquine (DP) in Sudan for the treatment of Plasmodium falciparum. The efficacy of chloroquine (CQ) and AL for the treatment of Plasmodium vivax was evaluated in Afghanistan and Somalia, respectively. Patients were treated and monitored for 28 (CQ, ASSP and AL) or 42 (DP) days. Polymerase chain reaction (PCR)-corrected cure rate and parasite positivity rate at Day 3 were estimated. Mutations in the P. falciparum kelch 13 (Pfk13) gene and amplifications of plasmepsin (Pfpm2) and multidrug resistance-1 (Pfmdr-1) genes were also studied.

RESULTS

A total of 1680 (249 for ASSP, 1079 for AL and 352 for DP) falciparum cases were successfully assessed. A PCR-adjusted ASSP cure rate of 100% was observed in Afghanistan and Pakistan. For AL, the cure rate was 100% in all but four sites in Sudan, where cure rates ranged from 92.1% to 98.8%. All but one patient were parasite-free at Day 3. For P. vivax, cure rates were 98.2% for CQ and 100% for AL. None of the samples from Afghanistan, Pakistan and Yemen had a Pfk13 mutation known to be associated with artemisinin resistance. In Sudan, the validated Pfk13 R622I mutation accounted for 53.8% (14/26) of the detected non-synonymous Pfk13 mutations, most of which were repeatedly detected in Gadaref. A prevalence of 2.7% and 9.3% of Pfmdr1 amplification was observed in Pakistan and Yemen, respectively.

CONCLUSION

High efficacy of ASSP, AL and DP in the treatment of uncomplicated falciparum infection and of CQ and AL in the treatment of P. vivax was observed in the respective countries. The repeated detection of a relatively high rate of Pfk13 R622I mutation in Sudan underscores the need for close monitoring of the efficacy of recommended ACTs, parasite clearance rates and Pfk13 mutations in Sudan and beyond. Registration numbers of the trials: ACTRN12622000944730 and ACTRN12622000873729 for Afghanistan, ACTRN12620000426987 and ACTRN12617001025325 for Pakistan, ACTRN12618001224213 for Somalia, ACTRN12617000276358, ACTRN12622000930785 and ACTRN12618001800213 for Sudan and ACTRN12617000283370 for Yemen.

Genomic characterization of Plasmodium falciparum genes associated with anti-folate drug resistance and treatment outcomes in eastern India: A molecular surveillance study from 2008 to 2017

Introduction

After being used vigorously for the previous two decades to treat P. falciparum, chloroquine and sulfadoxine-pyrimethamine were replaced in 2009 with an artemisinin-based combination therapy (artesunate-sulfadoxine-pyrimethamine) in an effort to combat multidrug-resistant parasites.

Methods

We set out to assess the genetic variants of sulfadoxine-pyrimethamine resistance and the effectiveness of its treatment in eastern India prior to, during, and 6 to 8 years following the introduction of the new pharmacological regime. In 2008-2009, 318 P. falciparum-positive patients got the recommended doses of sulfadoxine-pyrimethamine. We used 379 additional isolates from 2015 to 2017 in addition to the 106 isolates from 2010. All 803 isolates from two study sites underwent in vitro sulfadoxine-pyrimethamine sensitivity testing and genomic characterisation of sulfadoxine-pyrimethamine resistance (pfdhfr and pfdhps).

Results

In Kolkata and Purulia, we observed early treatment failure in 30.7 and 14.4% of patients, respectively, whereas recrudescence was found in 8.1 and 13.4% of patients, respectively, in 2008-2009. In 2017, the proportion of in vitro pyrimethamine and sulfadoxine resistance steadily grew in Kolkata and Purulia despite a single use of sulfadoxine-pyrimethamine. Treatment failures with sulfadoxine-pyrimethamine were linked to quintuple or quadruple pfdhfr- pfdhps mutations (AICII-AGKAT, AICII-AGKAA, AICII-SGKGT, AICII-AGKAA, AICNI-AGKAA) in 2008-2009 (p < 0.001). The subsequent spread of mutant-haplotypes with higher in vitro sulfadoxine-pyrimethamine resistance (p < 0.001), such as the sextuple (dhfr-AIRNI+dhps-AGEAA, dhfr-ANRNL+dhps-AGEAA) and septuple (dhfr-AIRNI+dhps-AGEAT), mutations were observed in 2015-2017.

Discussion

This successive spread of mutations with high in vitro sulfadoxine-pyrimethamine resistance confirmed the progressive increase in antifolate resistance even after an 8-year withdrawal of sulfadoxine-pyrimethamine.

Genetic Diversity and Population Genetic Analysis of Plasmodium falciparum Thrombospondin Related Anonymous Protein (TRAP) in Clinical Samples from Saudi Arabia

The thrombospondin related anonymous protein (TRAP) is considered one of the most important pre-erythrocytic vaccine targets. Earlier population genetic studies revealed the TRAP gene to be under strong balancing natural selection. This study is the first attempt to analyze genetic diversity, natural selection, phylogeography and population structure in 199 clinical samples from Saudi Arabia using the full-length PfTRAP gene. We found the rate of nonsynonymous substitutions to be significantly higher than that of synonymous substitutions in the clinical samples, indicating a strong positive or diversifying selection for the full-length gene and the Von Willebrand factor (VWF). The nucleotide diversity was found to be π~0.00789 for the full-length gene; however, higher nucleotide diversity was observed for the VWF compared to the thrombospondin repeat region (TSP). Deduction of the amino acid sequence alignment of the PNP repeat region in the Saudi samples revealed six genotypes characterized by tripeptide repeat motifs (PNP, ANP, ENP and SNP). Haplotype network, population structure and population differentiation analyses indicated four distinct sub-populations in spite of the low geographical distance between the sampling sites. Our results suggest the likeliness of independent parasite evolution, creating opportunities for further adaptation, including host transition, and making malaria control even more challenging.

Polymorphism analysis of pfmdr1 gene in Plasmodium falciparum isolates 11 years post-adoption of artemisinin-based combination therapy in Saudi Arabia

A total of 227 Plasmodium falciparum isolates from Jazan region, southwestern Saudi Arabia were amplified for the P. falciparum multi-drug resistance 1 (pfmdr1) gene to detect point mutations 11 years after the introduction of artemisinin-based combination therapy (ACT) in Saudi Arabia. The pfmdr1 86Y mutation was found in 11.5% (26/227) of the isolates while the N86 wild allele was detected in 88.5%. Moreover, 184F point mutations dominated (86.3%) the instances of pfmdr1 polymorphism while no mutation was observed at codons 1034, 1042 and 1246. Three pfmdr1 haplotypes were identified, NFSND (74.9%), NYSND (13.7%) and YFSND (11.4%). Associations of the prevalence of 86Y mutation and YFSND haplotype with participants' nationality, residency and parasitaemia level were found to be significant (P < 0.05). The findings revealed significant decline in the prevalence of the pfmdr1 86Y mutation in P. falciparum isolates from Jazan region over a decade after the implementation of ACT treatment. Moreover, the high prevalence of the NFSND haplotype might be indicative of the potential emergence of CQ-sensitive but artemether-lumefantrine-resistant P. falciparum strains since the adoption of ACT. Therefore, continuous monitoring of the molecular markers of antimalarial drug resistance in Jazan region is highly recommended.

The return of chloroquine-sensitive Plasmodium falciparum parasites in Jazan region, southwestern Saudi Arabia over a decade after the adoption of artemisinin-based combination therapy: analysis of genetic mutations in the pfcrt gene

This study investigated the polymorphism in the P. falciparum chloroquine resistance transporter (pfcrt) gene 11 years after chloroquine (CQ) cessation in Jazan region, southwestern Saudi Arabia. Two hundred and thirty-five P. falciparum isolates were amplified to detect mutations in the pfcrt gene. The pfcrt 76 T molecular marker for CQ resistance was detected in 66.4% (156/235) of the isolates, while the K76 CQ-sensitive wild type was detected in 33.6%. The pfcrt 74I and pfcrt 75E point mutations were each found to be present in 56.2% of isolates, while only four isolates (1.7%) were found to carry the pfcrt 72S mutation. Moreover, four pfcrt haplotypes were identified as follows: the CVIET triple-allele (56.2%), SVMET double-allele (1.7%) and CVMNT single-allele (8.5%) mutant haplotypes and the CVMNK wild haplotype (33.6%). The analysis also revealed significant associations between the prevalence of mutant pfcrt alleles and haplotypes and the age group, governorate and nationality of the patients as well as the parasitaemia level (p < 0.05). The findings provide evidence of the potential re-emergence of CQ-susceptible P. falciparum strains in Jazan region over a decade after CQ discontinuation, with about one third of the isolates analysed carrying the pfcrt K76 CQ-sensitive wild allele and the CVMNK ancestral wild haplotype. Although the reintroduction of CQ cannot be recommended at present in Saudi Arabia, these findings support the rationale for a potential future role for CQ in malaria treatment. Therefore, continuous molecular and in vitro monitoring mutations of pfcrt polymorphism in Jazan region is highly recommended.

Residual malaria in Jazan region, southwestern Saudi Arabia: the situation, challenges and climatic drivers of autochthonous malaria

Background

Saudi Arabia and Yemen are the only two countries in the Arabian Peninsula that are yet to achieve malaria elimination. Over the past two decades, the malaria control programme in Saudi Arabia has successfully reduced the annual number of malaria cases, with the lowest incidence rate across the country reported in 2014. This study aims to investigate the distribution of residual malaria in Jazan region and to identify potential climatic drivers of autochthonous malaria cases in the region.

Methods

A cross-sectional study was carried out from 1 April 2018 to 31 January 2019 in Jazan region, southwestern Saudi Arabia, which targeted febrile individuals attending hospitals and primary healthcare centres. Participants’ demographic data were collected, including age, gender, nationality, and residence. Moreover, association of climatic variables with the monthly autochthonous malaria cases reported during the period of 2010–2017 was retrospectively analysed.

Results

A total of 1124 febrile subjects were found to be positive for malaria during the study period. Among them, 94.3 and 5.7% were infected with Plasmodium falciparum and Plasmodium vivax, respectively. In general, subjects aged 18–30 years and those aged over 50 years had the highest (42.7%) and lowest (5.9%) percentages of malaria cases. Similarly, the percentage of malaria-positive cases was higher among males than females (86.2 vs 13.8%), among non-Saudi compared to Saudi subjects (70.6 vs 29.4%), and among patients residing in rural rather than in urban areas (89.8 vs 10.2%). A total of 407 autochthonous malaria cases were reported in Jazan region between 2010 and 2017. Results of zero-inflated negative binomial regression analysis showed that monthly average temperature and relative humidity were the significant climatic determinants of autochthonous malaria in the region.

Conclusion

Malaria remains a public health problem in most governorates of Jazan region. The identification and monitoring of malaria transmission hotspots and predictors would enable control efforts to be intensified and focused on specific areas and therefore expedite the elimination of residual malaria from the whole region.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-021-03846-4.

Current Epidemiological Characteristics of Imported Malaria, Vector Control Status and Malaria Elimination Prospects in the Gulf Cooperation Council (GCC) Countries

Malaria is the most common vector-borne parasitic infection causing significant human morbidity and mortality in nearly 90 tropical/sub-tropical countries worldwide. Significant differences exist in the incidence of malaria cases, dominant Plasmodium species, drug-resistant strains and mortality rates in different countries. Six Gulf Cooperation Council (GCC) countries (Bahrain, Kuwait, Qatar, Oman, Saudi Arabia and United Arab Emirates, UAE) in the Middle East region with similar climates, population demographics and economic prosperity are aiming to achieve malaria elimination. In this narrative review, all studies indexed in PubMed describing epidemiological characteristics of indigenous and imported malaria cases, vector control status and how malaria infections can be controlled to achieve malaria elimination in GCC countries were reviewed and discussed. These studies have shown that indigenous malaria cases are absent in Bahrain, Kuwait, Qatar and UAE and have progressively declined in Oman and Saudi Arabia. However, imported malaria cases continue to occur as GCC countries have large expatriate populations originating from malaria-endemic countries. Various malaria control and prevention strategies adopted by GCC countries including more stringent measures to reduce the likelihood of importing malaria cases by prior screening of newly arriving expatriates and vector elimination programs are likely to lead to malaria elimination in this region.