On the epidemiology of Plasmodium vivax malaria: past and present with special reference to the former USSR

Effects of CYP2D6 genotypes on Plasmodium vivax recurrence after primaquine treatment: A meta-analysis

OBJECTIVES

To elucidate the relationship between CYP2D6 polymorphisms and Plasmodium vivax recurrence in patients receiving primaquine-based treatment through systematic review and meta-analysis.

METHODS

We searched the PubMed, EMBASE, Cochrane Library, and Web of Science databases for eligible studies published up to August of 2021. We included studies investigating the associations between CYP2D6 polymorphisms and P. vivax recurrence. We evaluated the pooled odds ratio (OR) and 95% confidence interval (CI).

RESULTS

Data from nine studies, including 970 patients, were analyzed. We found that CYP2D6 poor metabolizers (PMs), intermediate metabolizers (IMs), or normal metabolizers slow (NM-Ss) were associated with a 1.8-fold (95% CI, 1.34-2.45; P = 0.0001) higher recurrence of P. vivax than normal metabolizers fast (NM-Fs), extensive metabolizers (EMs), or ultrarapid metabolizer (UMs). Subgroup analysis showed that studies on both Brazilian and Southeast or East Asian individuals had similar results to the main results. Sensitivity analysis by sequentially excluding individual studies also showed robust results (OR range: 1.63-2.01).

CONCLUSIONS

This meta-analysis confirmed that CYP2D6 PMs, IMs, or NM-Ss increased the risk of P. vivax recurrence compared to NM-Fs, EMs, or UMs. The results of this study could be used to predict P. vivax recurrence and suggest CYP2D6 genotype-based primaquine dosing.

Clinical impact of vivax malaria: A collection review

BACKGROUND

Plasmodium vivax infects an estimated 7 million people every year. Previously, vivax malaria was perceived as a benign condition, particularly when compared to falciparum malaria. Reports of the severe clinical impacts of vivax malaria have been increasing over the last decade.

METHODS AND FINDINGS

We describe the main clinical impacts of vivax malaria, incorporating a rapid systematic review of severe disease with meta-analysis of data from studies with clearly defined denominators, stratified by hospitalization status. Severe anemia is a serious consequence of relapsing infections in children in endemic areas, in whom vivax malaria causes increased morbidity and mortality and impaired school performance. P. vivax infection in pregnancy is associated with maternal anemia, prematurity, fetal loss, and low birth weight. More than 11,658 patients with severe vivax malaria have been reported since 1929, with 15,954 manifestations of severe malaria, of which only 7,157 (45%) conformed to the World Health Organization (WHO) diagnostic criteria. Out of 423 articles, 311 (74%) were published since 2010. In a random-effects meta-analysis of 85 studies, 68 of which were in hospitalized patients with vivax malaria, we estimated the proportion of patients with WHO-defined severe disease as 0.7% [95% confidence interval (CI) 0.19% to 2.57%] in all patients with vivax malaria and 7.11% [95% CI 4.30% to 11.55%] in hospitalized patients. We estimated the mortality from vivax malaria as 0.01% [95% CI 0.00% to 0.07%] in all patients and 0.56% [95% CI 0.35% to 0.92%] in hospital settings. WHO-defined cerebral, respiratory, and renal severe complications were generally estimated to occur in fewer than 0.5% patients in all included studies. Limitations of this review include the observational nature and small size of most of the studies of severe vivax malaria, high heterogeneity of included studies which were predominantly in hospitalized patients (who were therefore more likely to be severely unwell), and high risk of bias including small study effects.

CONCLUSIONS

Young children and pregnant women are particularly vulnerable to adverse clinical impacts of vivax malaria, and preventing infections and relapse in this groups is a priority. Substantial evidence of severe presentations of vivax malaria has accrued over the last 10 years, but reporting is inconsistent. There are major knowledge gaps, for example, limited understanding of the underlying pathophysiology and the reason for the heterogenous geographical distribution of reported complications. An adapted case definition of severe vivax malaria would facilitate surveillance and future research to better understand this condition.

Re-introduction of vivax malaria in a temperate area (Moscow region, Russia): a geographic investigation

Background

Between 1999 and 2008 Russia experienced a flare-up of transmission of vivax malaria following its massive importation with more than 500 autochthonous cases in European Russia, the Moscow region being the most affected. The outbreak waned soon after a decrease in importation in mid-2000s and strengthening the control measures. Compared with other post-eradication epidemics in Europe this one was unprecedented by its extension and duration.

Methods

The aim of this study is to identify geographical determinants of transmission. The degree of favourability of climate for vivax malaria was assessed by measuring the sum of effective temperatures and duration of season of effective infectivity using data from 22 weather stations. For geospatial analysis, the locations of each of 405 autochthonous cases detected in Moscow region have been ascertained. A MaxEnt method was used for modelling the territorial differentiation of Moscow region according to the suitability of infection re-emergence based on the statistically valid relationships between the distribution of autochthonous cases and environmental and climatic factors.

Results

In 1999–2004, in the beginning of the outbreak, meteorological conditions were extremely favourable for malaria in 1999, 2001 and 2002, especially within the borders of the city of Moscow and its immediate surroundings. The greatest number of cases occurred at the northwestern periphery of the city and in the adjoining rural areas. A significant role was played by rural construction activities attracting migrant labour, vegetation density and landscape division. A cut-off altitude of 200 m was observed, though the factor of altitude did not play a significant role at lower altitudes. Most likely, the urban heat island additionally amplified malaria re-introduction.

Conclusion

The malariogenic potential in relation to vivax malaria was high in Moscow region, albeit heterogeneous. It is in Moscow that the most favourable conditions exist for vivax malaria re-introduction in the case of a renewed importation. This recent event of large-scale re-introduction of vivax malaria in a temperate area can serve as a case study for further research.

Plasmodium vivax severe imported malaria in two migrants in France

BACKGROUND

With less than one severe case per year in average, Plasmodium vivax is very rarely associated with severe imported malaria in France. Two cases of P. vivax severe malaria occurred in patients with no evident co-morbidity. Interestingly, both cases did not occur at the primary infection but during relapses.

CASE PRESENTATIONS

Patient 1: A 27-year old male, born in Afghanistan and living in France since 2012, was admitted on August 2015 to the Avicenne hospital because of abdominal pain, intense headache, fever and hypotension. The patient was haemodynamically unstable despite 5 L of filling solution. A thin blood film showed P. vivax trophozoites within the red blood cells. To take care of the septic shock, the patient was given rapid fluid resuscitation, norepinephrine (0.5 mg/h), and intravenous artesunate. Nested polymerase chain reactions of the SSUrRNA gene were negative for Plasmodium falciparum but positive for P. vivax. The patient became apyretic in less than 24H and the parasitaemia was negative at the same time. Patient 2: A 24-year old male, born in Pakistan and living in France, was admitted on August 2016 because of fever, abdominal pain, headache, myalgia, and nausea. The last travel of the patient in a malaria endemic area occurred in 2013. A thin blood film showed P. vivax trophozoites within the red blood cells. The patient was treated orally by dihydroartemisinin-piperaquine and recovered rapidly. Nine months later, the patient returned to the hospital with a relapse of P. vivax malaria. The malaria episode was uncomplicated and the patient recovered rapidly. Three months later, the patient came back again with a third episode of P. vivax malaria. Following a rapid haemodynamic deterioration, the patient was transferred to the intensive care unit of the hospital. In all the patient received 10 L of filling solution to manage the septic shock. After 5 days of hospitalization and a specific treatment, the patient was discharged in good clinical conditions.

CONCLUSION

Clinicians should be aware of the potential severe complications associated with P. vivax in imported malaria, even though the primary infection is uncomplicated.

Role of malaria partners in malaria elimination in Armenia

Malaria control and preventive activities in the countries of the World Health Organization Region for Europe (WHO/EUR) were strengthened within the framework of the Regional Roll Back Malaria strategy adopted by the member-states at the beginning of the 2000s. A political document "From control to malaria elimination" known as the "Tashkent Declaration" was unanimously endorsed by the member-states of the WHO/EUR with malaria problems in 2005. Since then, considerable progress has been achieved in the countries of the region, signified by the dramatic reduction of malaria incidence in conjunction with the prevention of re-establishment of infection on the territories where malaria was eliminated earlier. Several countries of the region had been certified by the WHO as free of local malaria transmission as a result of the activities of their National Malaria Elimination Programme, Armenia being one of the first in 2011. One of the main lessons learnt during the implementation of the activities by the National Malaria Elimination Programme in Armenia was that the development of an operational plan for malaria elimination required a comprehensive national effort. Full support, both political and financial, from the highest levels of government to smooth coordination between different government ministries, such as Agriculture, Defense, Finance, Health and Policy and Planning and others, was a prerequisite for operational success. The role and place of various partners in the achievement of malaria elimination in the country is discussed in this review.

The rise and fall of long-latency Plasmodium vivax

Until World War II the only clinical phenotype of Plasmodium vivax generally recognised in medicine was one associated with either a long (8-9 months) incubation period or a similarly long interval between initial illness and the first relapse. Long-latency P. vivax 'strains' were the first in which relapse, drug resistance and pre-erythrocytic development were described. They were the infections in which primaquine radical cure dosing was developed. A long-latency 'strain' was the first to be fully sequenced. Although long-latency P. vivax is still present in some parts of Asia, North Africa and the Americas, in recent years it has been largely forgotten.

Effects of Climate Change and Heterogeneity of Local Climates оn the Development of Malaria Parasite (Plasmodium vivax) in Moscow Megacity Region

The article presents the results of a spatio-temporal analysis of the changes of the favorability of climatic conditions for the transmission of vivax malaria in the Moscow megacity and its surroundings during the period from 1977 to 2016. Using the historical temperature records at urban and rural weather stations, we calculated the key indicators of climate favorability for malaria transmission, viz. the sum of effective temperatures, the duration of the season of effective infectiveness, and a new integral index of climate favorability. We demonstrated a dramatic increase of all three indicators, which accelerated after 1984, and a high spatial heterogeneity among them. Due to the urban heat island effect, the degree of climatic favorability is especially high in the densely urbanized areas of Moscow megacity compared with the suburban and rural areas. Climatic conditions for vivax malaria in Moscow are better now than before. The season of effective infectiveness continues in the central part of the city for 25 days longer, and the integral index of climate favorability is 85% higher in comparison to mean values over the rural surroundings. The study contains an alert regarding the risk of malaria resurgence in the Moscow region in the case of the sufficient importation of cases from abroad.