Ovale Cases Research Articles

Clinical Implications and Procedural Complications in Patients with Patent Foramen Ovale Concomitant with Atrial Septal Aneurysm

Atrial septal aneurysm (ASA) is defined as excursion of the atrial septum exceeding 10 mm beyond the atrial septum into the right or left atrium, or a combined total excursion of 15 mm on the right and left sides during the cardiac cycle. According to previous studies, 20–40% of patent foramen ovale (PFO) cases are accompanied by ASAs. ASA is associated with the presence of PFO, left atrial dysfunction, cryptogenic stroke, migraine, and arterial embolism, thus making closure of PFO in patients with concomitant ASA necessary but challenging. The anatomy of ASAs associated with PFO has crucial effects on complications after the closure procedure; therefore, several factors must be considered. Herein, we review the clinical implications of concomitant PFO and ASA; discuss the complications occurring after the closure procedure; and provide practical guidance for the closure of concomitant PFO and ASA.

Epidemiological characterization of imported recurrent Plasmodium vivax and Plasmodium ovale in China, 2013\u20132020

BackgroundChina has reached important milestones in the elimination of malaria. However, the numbers of imported recurrent cases of Plasmodium vivax and P. ovale are gradually increasing, which increases the risk of malaria re-establishment in locations where Anopheles mosquitoes exist. The aim of this study is to characterize the epidemiological profiles of imported recurrent P. vivax and P. ovale cases, quantifying the recurrence burden and guiding the development of appropriate public health intervention strategies.MethodsIndividual-level data of imported recurrent P. vivax and P. ovale cases were collected from 2013 to 2020 in China via the Parasitic Diseases Information Reporting Management System. Demographic characteristics, temporal and spatial distributions, and the interval from previous infection to recurrence were analyzed by SAS, ArcGIS and GraphPad Prism software, respectively, to explore the epidemiological profiles of imported recurrent cases.ResultsA total of 307 imported recurrent cases, including 179 P. vivax and 128 P. ovale cases, were recorded. The majority of cases occurred in males (P. vivax 91.1%, P. ovale 93.8%) and migrant workers (P. vivax 43.2%, P. ovale 44.7%). Individuals aged 30–39 years had the highest P. vivax and P. ovale recurrent infection rates, respectively. The number of imported recurrent cases of infection by these two malaria species increased from 2013 to 2018, and P. vivax infection showed well-defined seasonality, with two peaks in February and June, respectively. More than 90% of patients with recurrent cases did not receive radical treatment for previous infection. Most imported recurrent P. vivax cases were reported in Yunnan Province and were imported from Myanmar, Ethiopia, and Pakistan, while most recurrent P. ovale cases were reported in southern China and primarily imported from Cameroon, Ghana, and Nigeria. The intervals from previous malaria infection to recurrence among different continents were significantly different (P = 0.0016) for P. vivax malaria but not for P. ovale malaria (P = 0.2373).ConclusionsThe large number of imported recurrent cases has been a major challenge in the prevention of malaria re-establishment in China. This study provides evidence to guide the development of appropriate public health intervention strategies for imported recurrent P. vivax and P. ovale cases.Graphic abstract

A Cluster of Plasmodium ovale Infections in Belgian Military Personnel after Deployment in Kindu, Democratic Republic of Congo: A Retrospective Study.

Plasmodium ovale malaria is often neglected due to its less severe course compared to Plasmodium falciparum. In 2011–2012, Belgian Armed Forces identified a cluster of P. ovale cases among military personnel after deployment in the Democratic Republic of Congo (DRC). In this retrospective, monocentric, observational study, clinical and biological features of soldiers diagnosed with P. ovale after deployment in DRC were reviewed. Species diagnosis was based on polymerase chain reaction (PCR) and/or thick blood smear. Medical records of 149 soldiers screened at the Queen Astrid Military Hospital after deployment were reviewed. Eight cases (seven P. ovale infections and one P. ovale—falciparum coinfection) were identified. All had positive thick smears, and seven were confirmed by PCR. Chemoprophylaxis was mefloquine in all subjects. Median time of disease onset was 101 days after return from the endemic region. Median delay between return and diagnosis was 103 days. All P. ovale bouts were uncomplicated. None had relapses after primaquine treatment. This military cohort highlights a hotspot of P. ovale in Eastern DRC. Non-specific symptoms, the less severe presentation, the lack of sensitive parasitological tools in the field and long delays between infection and symptoms probably lead to underestimation of P. ovale cases.

Comparison of Plasmodium ovale curtisi and Plasmodium ovale wallikeri infections by a meta-analysis approach

Malaria caused by Plasmodium ovale species is considered a neglected tropical disease with limited information about its characteristics. It also remains unclear whether the two distinct species P. ovale curtisi and P. ovale wallikeri exhibit differences in their prevalence, geographic distribution, clinical characteristics, or laboratory parameters. Therefore, this study was conducted to clarify these differences to support global malaria control and eradication programs. Studies reporting the occurrence of P. ovale curtisi and P. ovale wallikeri were explored in databases. Differences in proportion, clinical data, and laboratory parameters between the two species were estimated using a random-effects model and expressed as pooled odds ratios (ORs), mean difference (MD), or standardized MD depending on the types of extracted data. The difference in geographical distribution was visualized by mapping the origin of the two species. A total of 1453 P. ovale cases extracted from 35 studies were included in the meta-analysis. The p-value in the meta-analyses provided evidence favoring a real difference between P. ovale curtisi malaria cases (809/1453, 55.7%) and P. ovale wallikeri malaria cases (644/1453, 44.3%) (p: 0.01, OR 1.61, 95% CI 0.71–3.63, I2: 77%). Subgroup analyses established evidence favoring a real difference between P. ovale curtisi and P. ovale wallikeri malaria cases among the imported cases (p: 0.02, 1135 cases). The p value in the meta-analyses provided evidence favoring a real difference in the mean latency period between P. ovale curtisi (289 cases) and P. ovale wallikeri malaria (266 cases) (p: 0.03, MD: 27.59, 95% CI 1.99–53.2, I2: 94%), total leukocyte count (p < 0.0001, MD: 840, 95% CI 610–1070, I2: 0%, two studies) and platelet count (p < 0.0001, MD: 44,750, 95% CI 2900–60,500, I2: 32%, three studies). Four continents were found to have reports of P. ovale spp., among which Africa had the highest number of reports for both P. ovale spp. in its 37 countries, with a global proportion of 94.46%, and an almost equal distribution of both P. ovale spp., where P. ovale curtisi and P. ovale wallikeri reflected 53.09% and 46.90% of the continent’s proportion, respectively. This is the first systematic review and meta-analysis to demonstrate the differences in the characteristics of the two distinct P. ovale species. Malaria caused by P. ovale curtisi was found in higher proportions among imported cases and had longer latency periods, higher platelet counts, and higher total leukocyte counts than malaria caused by P. ovale wallikeri. Further studies with a larger sample size are required to confirm the differences or similarities between these two species to promote malaria control and effective eradication programs.

From elimination to post-elimination: Characteristics, challenges and re-transmission preventing strategy of imported malaria in China

Objective To analyze malaria epidemiological characteristics in China, 2010-2019, so as to provide evidence-based proof for target interventions on malaria elimination. Methods The data of web-based Infectious Disease Information Reporting Management System (IDIRMS) and Parasitic Diseases Information Reporting Management System (PDIRMS) from 2010 to 2019 were collected and analyzed. Results During 2010-2019, imported malaria cases were reported in all provinces, and in total 29 248 reported cases(2 925 cases annually), including 767 clinically diagnosed cases (2.62%), 7 388 Plasmodium vivax cases (25.26%), 18 032 P. falciparum cases (61.65%), 524 P. malariae cases (1.79%), 2 049 P. ovale cases (7.01%), 370 mixed-infection (1.27%), 2 P. knowlesi (0.01%), and 116 unclassified cases (0.40%). The imported malaria cases were mainly from Myanmar (2 750 cases, 9.40%), Ghana (2 606, 8.91%) and Nigeria (2 127, 7.27%); and most of them were reported in Yunnan (5 794, 19.81%), Guangxi (3 130, 10.70%) and Jiangsu (2 917, 9.97%). The temporal distribution was concentrated in June (4 141, 14.16%). Most cases (27 454, 93.87%) were found in male. A total of 181 deaths resulting from P. falciparum were reported. No obvious difference was found among interval from onset to diagnosis during the same timeframe ( P >0.05). From 2013 to 2019, the imported cases were mainly diagnosed (8 680, 39.75%) and reported (8 783, 40.22%) at county level. The proportion of diagnosis and report at county level exhibit an decreasing trend, while the municipal level was seen with a increasing trend. From 2013 to 2019, the imported cases were diagnosed (15 730, 72.03%) and reported (16 536, 75.72%) by medical institutions. The proportion of diagnosis and report by medical institutions exhibit an increasing trend, while the CDC institutions were observed with a decreasing trend. Conclusion To prevent the re-establishment caused by imported malaria, it is necessary to continue to strengthen inter-sectoral collaboration and surveillance, to carry out timely detection and appropriately treatment of imported cases, carefully investigate and assess the transmission risk of imported cases, and timely response to the risk foci or population. Furthermore, it is essential to conduct “strengthen inter-sectoral collaboration, timely case detection, promptly foci response” to effectively blocking the risk of re-establishment, and consolidating the achievements of malaria elimination. 摘要:目的 分析 2010—2019 年全国输人性疟疾疫情特征, 为各地消除疟疾后防止输人再传播工作提供依据。 方法 利用中国疾病预防控制中心疾病监测信息报告管理系统 (网络直报系统) 和寄生虫病监测信息报告管理系统 (寄生虫病专报系统), 收集 2010—2019 年全国输人性疟疾疫情数据资料, 建立数据库进行统计分析。 结果 2010—2019 年, 全国各省均有输人性疟疾病例分布, 共报告 29 248 例(年均 2 925 例), 其中临床诊断疟疾病例 767 例 (2.62%)、 间日疟 7 388 例 (25.26%)、恶性疟 18 032 例 (61.65%)、三日疟 524 例 (1.79%)、卵形疟 2 049 例 (7.01%)、诺氏疟 2 例 (0.01%)、混合感染 370 例 (1.27%) 和未分型病例 116 例 (0.40%)。病例主要输自缅甸 (2 750 例, 9.40%)、加纳 (2 606 例, 8.91%) 和尼日利亚 (2 127 例, 7.27%) 等国；主要分布在云南 (5 794 例, 19.81%)、广西 (3 130 例, 10.70%)和江苏 (2 917 例, 9.97%)等省份。病例主要在 6 月 (4 141 例, 14.16%) 报告。人群分布中以男性为主 (27 454 例, 93.87%)。死亡病例 181 例, 均为恶性疟。2010—2019 年病例发病到诊断时间间隔各年差异无统计学意义 ( P >0.05)。病例主要在县级机构 诊断 (8 680 例, 39.75%) 和报告 (8 783 例, 40.22%), 但呈逐年下降趋势, 地市级机构呈现明显上升趋势;主要在临床医疗 机构诊断 (15 730 例, 72.03%) 和报告 (16 536 例, 75.72%), 且逐年上升, 疾控机构比例在逐年下降。 结论 针对消除后 输人性疟疾的重大威胁, 应进一步加强部门间联防联控, 强化监测, 及时发现和规范治疗输人病例, 开展传播风险调査 和评估, 对风险疫点和重点人群进行及时响应和处置, 通过以“强化联防、及时发现、快速处置”为核心的综合性策略和 措施防止疟疾输人再传播, 巩固消除疟疾成果。

Misidentification of Plasmodium ovale as Plasmodium vivax malaria by a microscopic method: a meta-analysis of confirmed P. ovale cases

Plasmodium ovale is a benign tertian malaria parasite that morphologically resembles Plasmodium vivax. P. ovale also shares similar tertian periodicity and can cause relapse in patients without a radical cure, making it easily misidentified as P. vivax in routine diagnosis. Therefore, its prevalence might be underreported worldwide. The present study aimed to quantify the prevalence of P. ovale misidentified as P. vivax malaria using data from studies reporting confirmed P. ovale cases by molecular methods. Studies reporting the misidentification of P. ovale as P. vivax malaria were identified from three databases, MEDLINE, Web of Science, and Scopus, without language restrictions, but the publication date was restricted to 1993 and 2020. The quality of the included studies was assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS). The random-effects model was used to estimate the pooled prevalence of the misidentification of P. ovale as P. vivax malaria by the microscopic method when compared to those with the reference polymerase chain reaction method. Subgroup analysis of participants was also performed to demonstrate the difference between imported and indigenous P. ovale cases. The heterogeneity of the included studies was assessed using Cochran's Q and I2 statistics. Publication bias across the included studies was assessed using the funnel plot and Egger’s test, and if required, contour-enhanced funnel plots were used to identify the source(s) of funnel plot asymmetry. Of 641 articles retrieved from databases, 22 articles met the eligibility criteria and were included in the present study. Of the 8,297 malaria-positive cases identified by the PCR method, 453 P. ovale cases were confirmed. The pooled prevalence of misidentification of P. ovale as P. vivax malaria by the microscopic method was 11% (95% CI: 7–14%, I2: 25.46%). Subgroup analysis of the participants demonstrated a higher prevalence of misidentification in indigenous cases (13%, 95% CI: 6–21%, I2: 27.8%) than in imported cases (10%, 95% CI: 6–14%, I2: 24.1%). The pooled prevalence of misidentification of P. vivax as P. ovale malaria by the microscopic method was 1%, without heterogeneity (95% CI: 0–3%, I2: 16.8%). PCR was more sensitive in identifying P. ovale cases than the microscopic method (p < 0.00001, OR: 2.76, 95% CI: 1.83–4.15, I2: 65%). Subgroup analysis of participants demonstrated the better performance of PCR in detecting P. ovale malaria in indigenous cases (p: 0.0009, OR: 6.92, 95% CI: 2.21–21.7%, I2: 68%) than in imported cases (p: 0.0004, OR: 2.15, 95% CI: 1.41–3.29%, I2: 63%). P. ovale infections misidentified as P. vivax malaria by the microscopic method were frequent and led to underreported P. ovale cases. The molecular identification of P. ovale malaria in endemic areas is needed because a higher rate of P. ovale misidentification was found in endemic or indigenous cases than in imported cases. In addition, updated courses, enhanced training, and refreshers for microscopic examinations, particularly for P. ovale identification, are necessary to improve the microscopic identification of Plasmodium species in rural health centres where PCR is unavailable.

Analysis of imported malaria cases in Leshan City from 2012 to 2018

To analyze the epidemiological characteristics of reported malaria cases in Leshan City, so as to provide insights into malaria control. The data pertaining to malaria cases and epidemiological individual information in Leshan City from 2012 to 2018 were captured from the National Notifiable Communicable Disease Reporting System and the Information System for Parasitic Diseases Control and Prevention, and a descriptive epidemiological analysis was performed. A total of 34 malaria cases were reported in Leshan City from 2012 to 2018, and all cases were confirmed as imported malaria cases by Sichuan provincial malaria diagnosis reference laboratory. Of all 34 cases, there were 14 vivax malaria cases, 18 falciparum malaria cases, a malariae malaria case and an ovale malaria case. The sites where malaria parasite infections occurred mainly included African areas (accounting for 58.82%) and Southeastern Asian areas (accounting for 29.41%), and the malaria cases were mainly reported in January, February, June and July, which accounted for 65.63% of all cases. The cases included 33 men and a woman, and had ages of 21 to 59 years. The cases'occupations mainly involved overseas peasants, technical workers and businessmen. The duration from onset of malaria to diagnosis ranged from 0 to 31 days, and the percentage of definitive diagnosis was 85.29% at initial diagnosis. There are no local malaria cases in Leshan City; however, imported malaria cases are reported. The monitoring, management and health education of overseas returners should be further strengthened and malaria training should be improved to enhance the diagnostic and treatment capability in professionals, so as to consolidate malaria control achievements.

Characterization of Plasmodium ovale spp. imported from Africa to Henan Province, China

As indigenous malaria has decreased over recent decades, the increasing number of imported malaria cases has provided a new challenge for China. The proportion of imported cases due to Plasmodium ovale has increased during this time, and the difference between P. ovale curtisi and P. ovale wallikeri is of importance. To better understand P. ovale epidemiology and the differences between the two subspecies, information on imported malaria in Henan Province was collected during 2010–2017. We carried out a descriptive study to analyze the prevalence, proportion, distribution, and origin of P. o. curtisi and P. o. wallikeri. It showed that imported P. ovale spp. accounts for a large proportion of total malaria cases in Henan Province, even more than that of P. vivax. This suggests that the proportion of P. ovale cases is underestimated in Africa. Among these cases, the latency period of P. o. curtisi was significantly longer than that of P. o. wallikeri. More attention should be paid to imported ovale malaria to avoid the reintroduction of these two subspecies into China.

Intercurrent flaviviral viremia and Plasmodium ovale infection in ill returned travelers to Ontario

Purpose: Similar epidemiology and clinical presentations of arboviral infections and malaria along with the typically sequential approach to diagnostic testing, with malaria excluded urgently in febrile returned travelers, may mask the true epidemiology of such dual infections. Flaviviruses have been reported to trigger relapsing forms of malaria, including Plasmodium ovale, long after primary malarial infection, and this may delay the diagnosis of malaria. We aim to understand the incidence of intercurrent flaviviral infection in cases of confirmed Plasmodium ovale infection, where the flavivirus may have triggered relapse. Methods & Materials: DNA and RNA from biobanked isolates of P. ovale detected in whole blood at the Public Health Ontario Laboratory between 2006 and 2018 will be extracted and screened for intercurrent flaviviral infections using previously validated real-time PCR (qPCR) assays targeting multiple flaviviruses (pan-FLAV) and specifically dengue virus types 1–4 (DEN1, DEN2, DEN3, DEN4). Results: One-hundred fifteen unique isolates of P. ovale were identified over the reporting period, of which 62 had sufficient specimen for further molecular analysis. Among analyzed cases, over half occurred in males (36/62 [58%]), over a third occurred in females (23/36 [37%]), and 5% (3/62) had unassigned sex. Median age of P. ovale cases was 28.8 years (range 22 mos - 72 years; IQR 18.8–40.1 years). Median parasitemia was < 0.01% (range < 0.01% - 0.8%). Thirty (48%) P. ovale cases had documented travel history exclusively to Africa, with Nigeria as the most common source country (22/54 [40.1%]). Pan-FLAV assay yielded a 1.6% (1/62) positivity rate. DEN1-4 assay results are pending. Conclusion: P. ovale infections are most commonly imported to Ontario from West Africa, and Nigeria, specifically. Intercurrent flaviviral viremia was noted in at least 1.6%, which may suggest that primary flaviviral infection triggered a relapse of P. ovale. Alternatively, such co-occurrence may suggest primary infection with both organisms known to cause fever in returning travelers. Consideration of flaviviral co-infection should be given to the P. ovale patient with deep thrombocytopenia, lymphopenia, and high-yield arboviral symptomatology such as rash and retro-orbital headache. The influence of flaviviruses on the clinical course of P. ovale should be examined prospectively.

Increasing number of imported Plasmodium ovale wallikeri malaria in Shandong Province, China, 2015–2017

Since 2012, no indigenous malaria case have been reported in Shandong Province, China, whereas the number of imported cases and the genetic diversity of Plasmodium spp. have increased. Beginning in 2015, the number of Plasmodium ovale cases were increased and the P. ovale wallikeri malaria case began to arise. From 2015 to 2017, a total of 676 imported malaria cases were detected and 76 P. ovale spp. isolates were identified, of which 48 were P. ovale curtisi and 28 P. ovale wallikeri. The number of P. ovale wallikeri malaria cases increased yearly, six were identified in 2015, eight were identified in 2016, and 14 were identified in 2017. All cases with an attached travel history from Africa, with represented source countries of Equatorial Guinea (n = 9), Republic of the Congo (n = 4), and Democratic Republic of the Congo (n = 3). P. ovale wallikeri is increasing among travelers returning to Shandong Province from Africa. Although the P. ovale spp. infection rarely progressed to severity, this species is suspected to generate hypnozoites which have the potential to relapse. The ability to cause relapse is the threat to public health and should be concerned.

Imported malaria in pregnant women experienced in Japan.

With ever-growing global exchanges, the number of travelers, including pregnant women, to the tropics is increasing, which poses a risk of contracting malaria. Although there are several reports on imported malaria in pregnancy from Western countries, those focusing on cases experienced in Japan are very limited. We searched for cases of malaria in pregnancy in the treatment records submitted to the Research Group on Chemotherapy of Tropical Diseases, Japan, during the period 1993-2016. Literature searches were also conducted using an American and a Japanese search system. Ten cases of malaria in pregnant women were identified, including four cases with Plasmodium falciparum. Of eight evaluable cases, only one practiced malaria chemoprophylaxis. Among the nine evaluable cases, eight resulted in uneventful delivery and one P.falciparum case developed severe hepatic disturbance, disseminated intravascular coagulation, and intrauterine fetal death. After the initial attack, none of the Plasmodium vivax/Plasmodiumovale cases practiced chloroquine prophylaxis until delivery. One P. ovale case received a lower dose regimen of chloroquine as acute-stage therapy. This study demonstrated additional cases of imported malaria in pregnant women to the literature and highlighted various epidemiological, demographic, and clinical characteristics. Some of the clinical issues raised need to be investigated. Due to the paucity of the cases worldwide, sharing information among various countries is indispensable, and international guidelines which are now increasingly recommending the use of artemisinins in pregnant women should be referred.

Analysis of epidemiological characteristics of imported malaria cases in Chongqing Municipality in 2015

To analyze the laboratory diagnosis results and epidemiological characteristics of imported malaria cases in Chongqing Municipality in 2015. According to the Standard Operating Procedures of Malaria Diagnosis Reference Laboratory Manual, all the blood samples collected from the imported malaria patients were detected by microscopy, RDT and nest PCR. Meanwhile, the epidemiological data of the malaria cases were collected from the Parasitic Diseases Information Management System and analyzed. Totally 31 cases of imported malaria were reported in Chonqing Municipality in 2015, among which, there were 2 vivax malaria cases (6.45%), 23 falciparum malaria cases (74.19%), 5 ovale malaria cases (16.13%), 1 malariae malaria case (3.22%). For the 5 ovale cases, three of them were confirmed as Plasmodium ovale wallikeri infection. Among all the cases, 30 cases (96.77%) were from African countries, 1(3.33%) was from Southeast Asia. Thirty patients were male, and 1 was female. All the patients were aged from 23-61 years. There was no obvious seasonality in the case distribution. Both the medians of duration from malaria attack to first visiting a doctor and from first visiting a doctor to diagnosis were 2 days. The medical care units that the patients first visited were mainly county-level units, while those that made the diagnosis were mainly provincial level institutes. All the malaria cases in Chongqing in 2015 are imported, no local cases have been found, which suggests that this municipality still maintain the malaria elimination state. However, the monitoring and management of imported malaria cases as well as the training on malaria control for related medical staff still need to be strengthened.

Epidemiological analysis of malaria prevalence in Nanjing City from 2010 to 2015

To analyze the epidemiological characteristics of malaria in Nanjing City, so as to provide the evidence for further formulating and adjusting the malaria prevention and control strategy. The data of malaria situation, malaria cases and epidemiological investigations were collected from the Internet Reporting System in Nanjing City from 2010 to 2015 and analyzed statistically. A total of 137 confirmed malaria cases were reported in Nanjing City from 2010 to 2015, including 102 falciparum malaria cases (74.45%), 33 vivax malaria cases (24.09%), one ovale malaria case (0.73%) and one quartan malaria case (0.73%). Among the 137 malaria cases, 126 cases (91.97%) were imported from foreign countries, 2 cases (1.46%) were infected locally, and nine cases (6.57%) were imported from other provinces in China. Among the 126 overseas imported cases, 117 cases were imported from African countries and 9 from Asian countries. These malaria cases were majorly young men working as migrant workers, laborers and technical persons. About 19.30% of the cases went to hospital on onset day, and 55.65% were confirmed by medical institutions as malaria in the same day. The majority of diagnosis institutions were municipal hospitals (74.45%). The number of malaria cases in Nanjing City is declining year by year. The local infections are eliminating gradually. However, the situation of imported malaria from overseas is still serious. Therefore, the surveillance work and health education still should be strengthened, so as to reduce the risk of imported malaria.

The increasing importance of Plasmodium ovale and Plasmodium malariae in a malaria elimination setting: an observational study of imported cases in Jiangsu Province, China, 2011-2014.

BackgroundFollowing initiation of China’s National Malaria Elimination Action Plan in 2010, indigenous malaria infections in Jiangsu Province decreased significantly. Meanwhile imported Plasmodium infections have increased substantially, particularly Plasmodium ovale and Plasmodium malariae. Given the risk for malaria resurgence, there is an urgent need to understand the increase in imported P. ovale and P. malariae infections as China works to achieve national malaria elimination.MethodsAn observational study of imported malaria cases in Jiangsu Province, China was carried out for the period of 2011–2014.ResultsA total of 1268 malaria cases were reported in Jiangsu Province from 2011 to 2014. Although imported Plasmodium falciparum cases (n = 1058) accounted for 83.4 % of all reported cases in Jiangsu, P. ovale cases (14, 19, 30, and 46) and their proportion (3.7, 9.6, 8.8, and 13.0 %) of all malaria cases increased over the 4 years. Similarly, P. malariae cases (seven, two, nine, and 10) and proportion (1.9, 1.0, 2.6, and 2.8 %) of all malaria cases increased slightly during this time. A total of 98 cases of Plasmodium ovale curtisi (47/98, 48 %) and Plasmodium ovale wallikeri (51/98, 52 %) were identified as well. Latency periods were significant among these Plasmodium infections (p = 0.00). Also, this study found that the latency periods of P. ovale sp., P. malariae and Plasmodium vivax were significantly longer than P. falciparum. However, for both P. ovale curtisi and P. ovale wallikeri infections, the latency period analysis was not significant (p = 0.81). Misdiagnosis of both P. ovale and P. malariae was greater than 71.5 and 71.4 %, respectively. The P. ovale cases were misdiagnosed as P. falciparum (35 cases, 32.1 %), P. vivax (43 cases, 39.4 %) by lower levels of CDCs or hospitals. And, the P. malariae cases were misdiagnosed as P. falciparum (ten cases, 35.7 %), P. vivax (nine cases, 32.1 %) and P. ovale sp. (one case, 3.6 %). Geographic distribution of imported P. ovale sp. and P. malariae cases in Jiangsu Province mainly originated from sub-Saharan Africa such as Equatorial Guinea, Nigeria, and Angola.ConclusionsAlthough the vast majority of imported malaria cases were due to P. falciparum, the increase in other rare Plasmodium species originating from sub-Saharan Africa and Southeast Asia should be closely monitored at all levels of health providers focusing on diagnosis and treatment of malaria. In addition to a receptive vector environment, long latency periods and misdiagnosis of P. malariae and P. ovale sp. increase the risk of re-introduction of malaria in China.

Epidemiologic characteristics of Plasmodium ovale in China in 2011-2014

To investigate the epidemiological characteristics of Plasmodium ovale in 2011-2014 for malaria control policy making during the phase of malaria elimination in China. The data of individual Plasmodium ovale case (probable and confirmed) and population during 20011-2014 were collated from China National Notifiable Infectious Disease Reporting Information System, and the data of epidemiological investigation for individual Plasmodium ovale case (imported and indigenous) during 2011-2014 were collected from China Parasite Disease Prevention and Control Information System. All of the data didn't include China's Hongkong, Macao, Taiwan and foreign cases. The epidemiological characteristics, diagnosis and reporting were compared and analyzed. During study period of 2011-2014, a total of 373 Plasmodium ovale imported cases were reported, with male being 98.4% and median age being 40 years old. Jiangsu (100 cases), Guangxi (76 cases), Henan (55 cases), Anhui (28 cases) and Shandong(18 cases) reported Plasmodium ovale imported cases ranked the top 5 place in the list. Totally 182 counties from 21 provinces were reported Plasmodium ovale imported cases. 94.6% of ovale malaria imported cases (353/373) got infected from African countries and comprehensive hospitals, CDCs and hospital of infectious disease reported 40.0%, 37.8%, and 16.6% of Plasmodium ovale imported cases, respectively. 4 days of median time lag of Plasmodium ovale imported cases from date of onset to diagnosis was longer than 3 days. From 2011 to 2014, the rising number of Plasmodium ovale imported cases reported from wilder scope of China. Diagnosis time lag of Plasmodium ovale was longer than that of other Plasmodium. Diagnosis and prompt treatment of Plasmodium ovale imported cases and relapse case should be highlighted.

Molecular characterization of misidentified Plasmodium ovale imported cases in Singapore.

BackgroundPlasmodium ovale, considered the rarest of the malaria parasites of humans, consists of two morphologically identical but genetically distinct sympatric species, Plasmodium ovale curtisi and Plasmodium ovale wallikeri. These parasites resemble morphologically to Plasmodium vivax with which they also share a tertian periodicity and the ability to cause relapses, making them easily misidentified as P. vivax. Plasmodium ovale infections are rarely reported, but given the likelihood of misidentification, their prevalence might be underestimated.MethodsMorphological and molecular analysis of confirmed malaria cases admitted in Singapore in 2012–2014 detected nine imported P. ovale cases that had been misidentified as P. vivax. Since P. ovale had not been previously officially reported in Singapore, a retrospective analysis of available, frozen, archival blood samples was performed and returned two additional misidentified P. ovale cases in 2003 and 2006. These eleven P. ovale samples were characterized with respect to seven molecular markers (ssrRNA, Potra, Porbp2, Pog3p, dhfr-ts, cytb, cox1) used in recent studies to distinguish between the two sympatric species, and to a further three genes (tufa, clpC and asl).ResultsThe morphological features of P. ovale and the differential diagnosis with P. vivax were reviewed and illustrated by microphotographs. The genetic dimorphism between P. ovale curtisi and P. ovale wallikeri was assessed by ten molecular markers distributed across the three genomes of the parasite (Genbank KP050361-KP050470). The data obtained for seven of these markers were compared with those published and confirmed that both P. ovale species were present. This dimorphism was also confirmed for the first time on: (1) two genes from the apicoplast genome (tufA and clpC genes); and, (2) the asl gene that was used for phylogenetic analyses of other Plasmodium species, and that was found to harbour the highest number of dimorphic loci between the two P. ovale species.ConclusionMisidentified P. ovale infections are reported for the first time among imported malaria cases in Singapore. Genetic dimorphism between P. ovale curtisi and P. ovale wallikeri was confirmed using markers from the parasites’ three genomes. The apparent increase of imported P. ovale since 2012 (with yearly detection of cases) is puzzling. Given decrease in the overall number of malaria cases recorded in Singapore since 2010 the ‘resurgence’ of this neglected species raises public health concerns.Electronic supplementary materialThe online version of this article (doi:10.1186/s12936-015-0985-8) contains supplementary material, which is available to authorized users.

Optimal primaquine use for radical cure of Plasmodium vivax and Plasmodium ovale malaria in Japanese travelers--A retrospective analysis.

Recently, a dose of 30 mg (base) primaquine daily for 14 days is increasingly recommended for radical cure of Plasmodium vivax malaria. However, total primaquine doses, or those per body weight, are also recognized as important. In Japan, primaquine is not a licensed medicine, but has been used through the Research Group on Chemotherapy of Tropical Diseases for >3 decades. Based on clinical records submitted to the Research Group, patients with P. vivax and Plasmodium ovale malaria treated with primaquine were analyzed to determine the efficacy and safety of the antimalarial drug. Seventy-five P. vivax cases, including 3 in children, and 19 P. ovale cases were enrolled. Five of the P. vivax cases demonstrated at least one relapse despite primaquine therapy. Total primaquine doses per body weight were obtained in 4 of the 5 relapsed patients, presenting 9 malaria episodes totally, and most of the primaquine failures were caused with a total dose ≤ 3.5 mg/kg. Liver function disturbance was reported in 2 cases. In order to optimize radical cure of P. vivax, the total primaquine dose per body weight should be considered, at least 3.5 mg/kg or even more if contracted in countries with significant drug resistance. Possibility of primaquine hepatotoxicity in chronic liver disease patients remains to be elucidated.

Plasmodium ovale curtisi and Plasmodium ovale wallikeri in North-West Ethiopia.

BackgroundIn Ethiopia Plasmodium falciparum and Plasmodium vivax are the dominant species accounting for roughly 60 and 40% of malaria cases, respectively. Recently a major shift from P. falciparum to P. vivax has been observed in various parts of the country but the epidemiology of the other human malaria species, Plasmodium ovale spp. and Plasmodium malariae remains poorly understood. The aim of this study was to assess P. ovale curtisi and wallikeri infection in north-west Ethiopia by using microscopy and nested PCR.MethodsA health institution-based survey using non-probability sampling techniques was conducted at Maksegnet, Enfranze and Kola Diba health centres and Metema hospital in North Gondar. Three-hundred patients with signs and symptoms consistent with malaria were included in this study and capillary blood was collected for microscopic examination and molecular analysis of Plasmodium species. Samples were collected on Whatman 903 filter papers, stored in small plastic bags with desiccant and transported to Vienna (Austria) for molecular analysis. Data from study participants were entered and analysed by SPSS 20 software.ResultsOut of 300 study participants (167 males and 133 females), 184 samples were classified positive for malaria (133 P. falciparum and 51 P. vivax) by microscopy. By species-specific PCR 233 Plasmodium spp (95% CI: 72.6-82) were detected and the majority 155 (66.5%, 95% CI: 60.2-72.3) were P. falciparum followed by P. vivax 69 (29.6%, 95% CI; 24.1-35.8) and 9 (3.9%, 95% CI: 2-7.2) samples were positive for P. ovale. Seven of P. ovale parasites were confirmed as P. ovale wallikeri and two were confirmed as P. ovale curtisi. None of the samples tested positive for P. malariae. During microscopic examination there were high (16.3%) false negative reports and all mixed infections and P. ovale cases were missed or misclassified.ConclusionThis study indicates that P. ovale malaria is under-reported in Ethiopia and provides the first known evidence of the sympatric distribution of indigenous P. ovale wallikeri and P. ovale curtisi in Ethiopia. Therefore, further studies assessing the prevalence of the rare species P. ovale and P. malariae are urgently needed to better understand the species distribution and to adapt malaria control strategies.

日本人の三日熱マラリア・卵形マラリア症例に対するプリマキンの使用経験

Primaquine phosphate has been used to prevent relapse as a radical cure after the acute-phase treatment of vivax and ovale malaria however. Many vivax malaria relapses have been reported following a standard dose of primaquine (15 mg/day for 14 days). A higher dose of primaquine (30 mg/day for 14 days) decreases the relapse rate, and the concomitant risk of gastrointestinal side effects tends to disappear when the drug is administered with food. G6PD deficiency is rare in the Japanese population. Although the relapsed phenomenon is reported globally, the higher dose of primaquine is currently recommended in Japan only for those returning from Southeast Asia or Papua New Guinea. Cases of 18 Japanese, including 13 vivax malaria and 5 ovale malaria, prescribed primaquine at a referral center in Japan, were analyzed retrospectively from 2007-2011. Data on diagnosis, treatment, and outcome were extracted from medical records. Of the 18, 10 with vivax malaria were administered the higher dose of primaquine. We found that only one suffered relapse-a vivax malarial case returning from Brazil and treated with the standard dose of primaquine. No ovale malarial case suffered relapse. None, including the 10 prescribed the higher primaquine dose, experienced any adverse side effects. Based on our findings, we recommend a higher dose of primaquine be used to prevent relapse when treating Japanese suffering from vivax malaria.

An 8-year survey on the occurrence of imported malaria in a nonendemic area by microscopy and molecular assays

Our study aimed to describe the occurrence of imported malaria in a nonendemic area (Parma, Italy) during the period 2000 to 2007, comparing the data obtained by microscopy and molecular assays targeting plasmodial 18S subunit rRNA gene. The prevalence of imported malaria in Parma was 21.8% by microscopy and 22.7% by polymerase chain reaction (PCR). Plasmodium falciparum accounted for 81.1% of the cases, followed by Plasmodium ovale (8.8%), Plasmodium vivax (3.8%), and Plasmodium malariae (1.9%). Mixed infections accounted for 4.4% of the cases. In this study, PCRs proved to be more sensitive and specific than microscopy and changed the picture of malaria epidemiology in Parma, detecting additional cases of malaria undiagnosed by microscopy and allowing speciation of plasmodia in cases misidentified by microscopy. Generally, imported malaria cases reflect the number of immigrants who visit their native countries, in particular, West Africa, explaining the increased prevalence of P. ovale cases among non- P. falciparum infections in Parma.