Delayed care-seeking in international migrant workers with imported malaria in China

BACKGROUND

Imported malaria cases continue to pose major challenges in China as well as in other countries that have achieved elimination. Early diagnosis and treatment of each imported malaria case is the key to successfully maintaining malaria elimination success. This study aimed to build an easy-to-use predictive nomogram to predict and intervene against delayed care-seeking among international migrant workers with imported malaria.

METHODS

A prediction model was built based on cases with imported malaria from 2012 to 2019, in Jiangsu Province, China. Routine surveillance information (e.g. sex, age, symptoms, origin country and length of stay abroad), data on the place of initial care-seeking and the gross domestic product (GDP) of the destination city were extracted. Multivariate logistic regression was performed to identify independent predictors and a nomogram was established to predict the risk of delayed care-seeking. The discrimination and calibration of the nomogram was performed using area under the curve and calibration plots. In addition, four machine learning models were used to make a comparison.

RESULTS

Of 2255 patients with imported malaria, 636 (28.2%) sought care within 24 h after symptom onset, and 577 (25.6%) sought care 3 days after symptom onset. Development of symptoms before entry into China, initial care-seeking from superior healthcare facilities and a higher GDP level of the destination city were significantly associated with delayed care-seeking among migrant workers with imported malaria. Based on these independent risk factors, an easy-to-use and intuitive nomogram was established. The calibration curves of the nomogram showed good consistency.

CONCLUSIONS

The tool provides public health practitioners with a method for the early detection of delayed care-seeking risk among international migrant workers with imported malaria, which may be of significance in improving post-travel healthcare for labour migrants, reducing the risk of severe malaria, preventing malaria reintroduction and sustaining achievements in malaria elimination.

[Quantitative analysis of risk assessment indicators for re-introduction of imported malaria in China]

OBJECTIVE

To quantitatively analyze the risk indicators of re-introduction of imported malaria in China and their weighting coefficients, so as to investigate the difference in the contribution of risk indicators included in the current risk assessment framework for re-introduction of imported malaria in China to the risk assessment of re-introduction of imported malaria.

METHODS

Publications pertaining to the risk assessment framework for re-introduction of imported malaria in China that reported the risk indicators and their weighting coefficients were retrieved in PubMed, Web of Science, CNKI, Wanfang Data, and VIP with terms of "malaria", "re-introduction/re-transmission/re-establishment", "risk assessment/risk evaluation/risk prediction" from the inception of the database through 3 August 2023, and literature search was performed in Google Scholar to ensure the comprehensiveness of the retrieval. Basic characteristics of included studies were extracted using pre-designed information extraction forms by two investigators, and data pertaining to risk indicators of re-introduction of imported malaria were cross-checked by these two investigators. The risk indicators included in the risk assessment framework for re-introduction of imported malaria in China and their weighting coefficients were visualized with the Nightingale's rose diagrams using the software R 4.2.1, and the importance of risk indictors was evaluated with the frequency of risk indicators included in the risk assessment framework and the ranking of weighting coefficients of risk indicators. In addition, the capability of risk indicators screened by different weighting methods was compared by calculating the ratio of the maximum to the minimum of the weighting coefficients of the risk indicators screened by different weighting methods.

RESULTS

A total of 2 138 publications were retrieved, and following removal of duplications and screening, a total of 8 publications were included in the final analysis. In these 8 studies, 8 risk assessment frameworks for re-introduction of imported malaria in China and 52 risk indicators of re-introduction of imported malaria were reported, in which number of imported malaria cases (n = 8) and species of malaria vectors were more frequently included in the risk assessment frameworks (n = 8), followed by species of imported malaria parasites (n = 6) and population density of local malaria vectors (n = 6), and species of local malaria vectors (n = 6), number of imported malaria cases (n = 5) and species of imported malaria parasites had the three highest weighting coefficients (n = 4). The weighting methods included expert scoring method, combination of expert scoring method and analytic hierarchy process, and combination of expert scoring method and entropy weight method in these 8 studies, and the ratios of the maximum to the minimum of the weighting coefficients of the risk indicators screened by the expert scoring method were 1.143 to 2.241, while the ratios of the maximum to the minimum of the weighting coefficients of the risk indicators screened by combination of the expert scoring method and analytic hierarchy process were 34.970 to 162.000.

CONCLUSIONS

Number of imported malaria cases, species of imported malaria parasites, species of local malaria vectors and population density of local malaria vectors are core indicators in the current risk assessment framework for re-introduction of imported malaria in China. Combination of the expert scoring method and analytic hierarchy process is superior to the expert scoring method alone for weighting the risk indicators.

Individual perceptions of community efficacy for non-communicable disease management in twelve communities in China: cross-sectional and longitudinal analyses

OBJECTIVES

This objective of this study was to use empirical data to assess cross-sectional variation singular and changes over time in community efficacy for non-communicable diseases (NCDs) management (COEN) and to examine individual factors associated with changes in COEN.

STUDY DESIGN

This was a longitudinal observational study.

METHODS

Participants with hypertension and diabetes were randomly selected from 12 communities from three cities in eastern China, and a baseline survey and a 1-year follow-up were conducted. The COEN scale has five dimensions: community physical environment (CPE), behavioral risk factors (BRF), mental health and social relationships (MHSR), community health management (CHM), and community organisations and activities (COA). Mixed-effects models were used to investigate the change in COEN over time and the association between individual factors and changes in COEN.

RESULTS

COEN scores showed significant variation singular among the 12 communities (P < 0.001) at the baseline. In the mixed-effects model, CPE (β coefficient: 1.62, P < 0.001), BRF (0.90, P < 0.001), MHSR (0.86, P < 0.001), CHM (0.46, P < 0.001), and total scores (β = 3.57, P < 0.001) increased significantly over time. The changes in COEN were associated with individual characteristics (e.g., older, men, more educated).

CONCLUSIONS

Cross-sectional variations and changes over time in COEN demonstrated the utility of a sensitive instrument. Factors such as age, gender, marriage, education level, and employment may affect the financial and social resources assignment for NCD management. Our findings suggest that further high-quality studies are needed to better evaluate the effect of community empowerment on the prevention and control of NCDs.

Assessing the risk of malaria local transmission and re-introduction in China from pre-elimination to elimination: A systematic review

Assessing the risk of malaria local transmission and re-introduction is crucial for the preparation and implementation of an effective elimination campaign and the prevention of malaria re-introduction in China. Therefore, this review aims to evaluate the risk factors for malaria local transmission and re-introduction in China over the period of pre-elimination to elimination. Data were obtained from six databases searched for studies that assessed malaria local transmission risk before malaria elimination and re-introduction risk after the achievement of malaria elimination in China since the launch of the NMEP in 2010, employing the keywords "malaria" AND ("transmission" OR "re-introduction") and their synonyms. A total of 8,124 articles were screened and 53 articles describing 55 malaria risk assessment models in China from 2010 to 2023, including 40 models assessing malaria local transmission risk (72.7%) and 15 models assessing malaria re-introduction risk (27.3%). Factors incorporated in the 55 models were extracted and classified into six categories, including environmental and meteorological factors (39/55, 70.9%), historical epidemiology (35/55, 63.6%), vectorial factors (32/55, 58.2%), socio-demographic information (15/26, 53.8%), factors related to surveillance and response capacity (18/55, 32.7%), and population migration aspects (13/55, 23.6%). Environmental and meteorological factors as well as vectorial factors were most commonly incorporated in models assessing malaria local transmission risk (29/40, 72.5% and 21/40, 52.5%) and re-introduction risk (10/15, 66.7% and 11/15, 73.3%). Factors related to surveillance and response capacity and population migration were also important in malaria re-introduction risk models (9/15, 60%, and 6/15, 40.0%). A total of 18 models (18/55, 32.7%) reported the modeling performance. Only six models were validated internally and five models were validated externally. Of 53 incorporated studies, 45 studies had a quality assessment score of seven and above. Environmental and meteorological factors as well as vectorial factors play a significant role in malaria local transmission and re-introduction risk assessment. The factors related to surveillance and response capacity and population migration are more important in assessing malaria re-introduction risk. The internal and external validation of the existing models needs to be strengthened in future studies.

Elicitation of T-cell-derived IFN-γ-dependent immunity by highly conserved Plasmodium ovale curtisi Duffy binding protein domain region II (PocDBP-RII)

BACKGROUND

Infections with Plasmodium ovale are widely distributed but rarely investigated, and the resulting burden of disease has been underestimated. Plasmodium ovale curtisi Duffy binding protein domain region II (PocDBP-RII) is an essential ligand for reticulocyte recognition and host cell invasion by P. ovale curtisi. However, the genomic variation, antigenicity and immunogenicity of PocDBP-RII remain major knowledge gaps.

METHODS

A total of 93 P. ovale curtisi samples were collected from migrant workers who returned to China from 17 countries in Africa between 2012 and 2016. The genetic polymorphism, natural selection and copy number variation (CNV) were investigated by sequencing and real-time PCR. The antigenicity and immunogenicity of the recombinant PocDBP-RII (rPocDBP-RII) protein were further examined, and the humoral and cellular responses of immunized mice were assessed using protein microarrays and flow cytometry.

RESULTS

Efficiently expressed and purified rPocDBP-RII (39 kDa) was successfully used as an antigen for immunization in mice. The haplotype diversity (Hd) of PocDBP-RII gene was 0.105, and the nucleotide diversity index (π) was 0.00011. No increased copy number was found among the collected isolates of P. ovale curtisi. Furthermore, rPocDBP-RII induced persistent antigen-specific antibody production with a serum IgG antibody titer of 1: 16,000. IFN-γ-producing T cells, rather than IL-10-producing cells, were activated in response to the stimulation of rPocDBP-RII. Compared to PBS-immunized mice (negative control), there was a higher percentage of CD4+CD44highCD62L- T cells (effector memory T cells) and CD8+CD44highCD62L+ T cells (central memory T cells) in rPocDBP-RII‑immunized mice.

CONCLUSIONS

PocDBP-RII sequences were highly conserved in clinical isolates of P. ovale curtisi. rPocDBP-RII protein could mediate protective blood-stage immunity through IFN-γ-producing CD4+ and CD8+ T cells and memory T cells, in addition to inducing specific antibodies. Our results suggested that rPocDBP-RII protein has potential as a vaccine candidate to provide assessment and guidance for malaria control and elimination activities.

[Risk predictive models of healthcare-seeking delay among imported malaria patients in Jiangsu Province based on the machine learning]

OBJECTIVE

To create risk predictive models of healthcare-seeking delay among imported malaria patients in Jiangsu Province based on machine learning algorithms, so as to provide insights into early identification of imported malaria cases in Jiangsu Province.

METHODS

Case investigation, first symptoms and time of initial diagnosis of imported malaria patients in Jiangsu Province in 2019 were captured from Infectious Disease Report Information Management System and Parasitic Disease Prevention and Control Information Management System of Chinese Center for Disease Control and Prevention. The risk predictive models of healthcare-seeking delay among imported malaria patients were created with the back propagation (BP) neural network model, logistic regression model, random forest model and Bayesian model using thirteen factors as independent variables, including occupation, species of malaria parasite, main clinical manifestations, presence of complications, severity of disease, age, duration of residing abroad, frequency of malaria parasite infections abroad, incubation period, level of institution at initial diagnosis, country of origin, number of individuals travelling with patients and way to go abroad, and time of healthcare-seeking delay as a dependent variable. Logistic regression model was visualized using a nomogram, and the nomogram was evaluated using calibration curves. In addition, the efficiency of the four models for prediction of risk of healthcare-seeking delay among imported malaria patients was evaluated using the area under curve (AUC) of receiver operating characteristic curve (ROC). The importance of each characteristic was quantified and attributed by using SHAP to examine the positive and negative effects of the value of each characteristic on the predictive efficiency.

RESULTS

A total of 244 imported malaria patients were enrolled, including 100 cases (40.98%) with the duration from onset of first symptoms to time of initial diagnosis that exceeded 24 hours. Logistic regression analysis identified a history of malaria parasite infection [odds ratio (OR) = 3.075, 95% confidential interval (CI): (1.597, 5.923)], long incubation period [OR = 1.010, 95% CI: (1.001, 1.018)] and seeking healthcare in provincial or municipal medical facilities [OR = 12.550, 95% CI: (1.158, 135.963)] as risk factors for delay in seeking healthcare among imported malaria cases. BP neural network modeling showed that duration of residing abroad, incubation period and age posed great impacts on delay in healthcare-seek among imported malaria patients. Random forest modeling showed that the top five factors with the greatest impact on healthcare-seeking delay included main clinical manifestations, the way to go abroad, incubation period, duration of residing abroad and age among imported malaria patients, and Bayesian modeling revealed that the top five factors affecting healthcare-seeking delay among imported malaria patients included level of institutions at initial diagnosis, age, country of origin, history of malaria parasite infection and individuals travelling with imported malaria patients. ROC curve analysis showed higher overall performance of the BP neural network model and the logistic regression model for prediction of the risk of healthcare-seeking delay among imported malaria patients (Z = 2.700 to 4.641, all P values < 0.01), with no statistically significant difference in the AUC among four models (Z = 1.209, P > 0.05). The sensitivity (71.00%) and Youden index (43.92%) of the logistic regression model was higher than those of the BP neural network (63.00% and 36.61%, respectively), and the specificity of the BP neural network model (73.61%) was higher than that of the logistic regression model (72.92%).

CONCLUSIONS

Imported malaria cases with long duration of residing abroad, a history of malaria parasite infection, long incubation period, advanced age and seeking healthcare in provincial or municipal medical institutions have a high likelihood of delay in healthcare-seeking in Jiangsu Province. The models created based on the logistic regression and BP neural network show a high efficiency for prediction of the risk of healthcare-seeking among imported malaria patients in Jiangsu Province, which may provide insights into health management of imported malaria patients.

[Acetylcorynoline inhibits microglia activation by regulating EGFR/MAPK signaling to promote functional recovery of injured mouse spinal cord]

OBJECTIVE

To investigate the effect of acetylcorynoline (Ace) for promoting functional recovery of injured spinal cord in rats and explore the underlying mechanism.

METHODS

Rat models of spinal cord injury (SCI) were treated with intraperitoneal injection of different concentrations of Ace, with the sham-operated rats as the control group. After the treatment, the changes in motor function of the rats and the area of spinal cord injury were assessed with BBB score and HE staining, and the changes in pro-inflammatory cytokine levels and microglial activation were determined using PCR, ELISA and immunofluorescence staining. In a lipopolysaccharide (LPS)-treated BV2 cell model, the effects of different concentrations of Ace or DMSO on microglial activation and inflammatory cytokine production were observed. Network pharmacology analysis was performed to predict the target protein and signaling mechanism that mediated the inhibitory effect of Ace on microglia activation, and AutoDock software was used for molecular docking between Ace and the target protein. A signaling pathway blocker (Osimertinib) was used to verify the signaling mechanism in rat models of SCI and LPS-treated BV2 cell model.

RESULTS

In rat models of SCI, Ace treatment significantly increased the BBB score, reduced the area of spinal cord injury, and lowered the number of activated microglia cells and the levels of pro-inflammatory cytokines (P < 0.05). The cell experiments showed that Ace treatment significantly lower the level of cell activation and the production of inflammatory cytokines in LPS-treated BV2 cells (P < 0.05). Network pharmacology analysis suggested that EGFR was the main target of Ace, and they bound to each other via hydrogen bonds as shown by molecular docking. Western blotting confirmed that Ace inhibited the activation of the EGFR/MAPK signaling pathway in injured mouse spinal cord tissue and in LPS-treated BV2 cells, and its inhibitory effect was comparable to that of Osimertinib.

CONCLUSION

In rat models of SCI, treatment with Ace can inhibit microglia-mediated inflammatory response by regulating the EGFR/MAPK pathway, thus promoting tissue repair and motor function recovery.

Predicting the risk of malaria re-introduction in countries certified malaria-free: a systematic review

BACKGROUND

Predicting the risk of malaria in countries certified malaria-free is crucial for the prevention of re-introduction. This review aimed to identify and describe existing prediction models for malaria re-introduction risk in eliminated settings.

METHODS

A systematic literature search following the PRISMA guidelines was carried out. Studies that developed or validated a malaria risk prediction model in eliminated settings were included. At least two authors independently extracted data using a pre-defined checklist developed by experts in the field. The risk of bias was assessed using both the prediction model risk of bias assessment tool (PROBAST) and the adapted Newcastle-Ottawa Scale (aNOS).

RESULTS

A total 10,075 references were screened and 10 articles describing 11 malaria re-introduction risk prediction models in 6 countries certified malaria free. Three-fifths of the included prediction models were developed for the European region. Identified parameters predicting malaria re-introduction risk included environmental and meteorological, vectorial, population migration, and surveillance and response related factors. Substantial heterogeneity in predictors was observed among the models. All studies were rated at a high risk of bias by PROBAST, mostly because of a lack of internal and external validation of the models. Some studies were rated at a low risk of bias by the aNOS scale.

CONCLUSIONS

Malaria re-introduction risk remains substantial in many countries that have eliminated malaria. Multiple factors were identified which could predict malaria risk in eliminated settings. Although the population movement is well acknowledged as a risk factor associated with the malaria re-introduction risk in eliminated settings, it is not frequently incorporated in the risk prediction models. This review indicated that the proposed models were generally poorly validated. Therefore, future emphasis should be first placed on the validation of existing models.

Poor performance of malaria rapid diagnostic tests for the detection of Plasmodium malariae among returned international travellers in China

BACKGROUND

Malaria is a worldwide infectious disease. For countries that have achieved malaria elimination, the prevention of re-establishment due to infections in returned travellers has become important. The accurate and timely diagnosis of malaria is the key in preventing re-establishment, and malaria rapid diagnostic tests (RDTs) are frequently used due to their convenience. However, the RDT performance in Plasmodium malariae (P. malariae) infection diagnosis remains unknown.

METHODS

This study analysed epidemiological features and diagnosis patterns of imported P. malariae cases from 2013 to 2020 in Jiangsu Province and evaluated the sensitivity of four parasite enzyme lactate dehydrogenase (pLDH)-targeting RDTs (Wondfo, SD BIONLINE, CareStart and BioPerfectus) and one aldolase-targeting RDT(BinaxNOW) for P. malariae detection. Furthermore, influential factors were investigated, including parasitaemia load, pLDH concentration and target gene polymorphisms.

RESULTS

The median duration from symptom onset to diagnosis among patients with P. malariae infection was 3 days, which was longer than that with Plasmodium falciparum (P. falciparum) infection. The RDTs had a low detection rate (39/69, 56.5%) among P. malariae cases. All tested RDT brands had poor performance in P. malariae detection. All the brands except the worst-performing SD BIOLINE, achieved 75% sensitivity only when the parasite density was higher than 5000 parasites/μL. Both pLDH and aldolase showed relatively conserved and low gene polymorphism rates.

CONCLUSIONS

The diagnosis of imported P. malariae cases was delayed. The RDTs had poor performance in P. malariae diagnosis and may threaten the prevention of malaria re-establishment from returned travellers. The improved RDTs or nucleic acid tests for P. malariae cases are urgently needed for the detection of imported cases in the future.

[Regular assessment is an effective approach to maintaining the capacity of prevention of re-establishment from imported malaria in China]

After achieving malaria elimination, preventing re-establishment from imported malaria and consolidating malaria elimination achievements are top priorities of the national malaria control program in China. Due to the long-term existence of overseas imported malaria cases and incomplete eradication of local epidemic conditions, there are multiple challenges for prevention of re-establishment from imported malaria in China. Hereby, we propose that regular assessment is an effective approach to maintaining the capability of prevention of re-establishment from imported malaria, and describe the purpose, significance, management and implementation of the capability assessment for prevention of re-establishment from imported malaria, so as to provide insights into the formulation and adjustment of malaria control strategies during the post-elimination phase.

Prognostic value of combined pre- and postoperative albumin-to-alkaline phosphatase ratio for patients with hepatocellular carcinoma undergoing trans-catheter chemoembolisation

AIM

To reveal the prognostic value of the postoperative and dynamic albumin-to-alkaline phosphatase ratio (AAPR) in hepatocellular carcinoma (HCC) patients undergoing trans-catheter chemoembolisation (TACE).

MATERIALS AND METHODS

In total, 545 HCC patients undergoing initial TACE were enrolled into the study. The receiver operating characteristic (ROC) curve was plotted to determine the best cut-off for AAPR. Univariate and multivariate Cox regression analyses were used to confirm the independent prognostic effect of AAPR on overall survival (OS). The predictive performance of AAPR was assessed by ROC curves, concordance index (C-index), and Akaike information criterion (AIC), and was compared to existing liver function assessment systems.

RESULTS

The optimal cut-off value for the AAPR was 0.26. Elevated AAPR (>0.26) was associated with a low risk of death after adjustment whether before (HR: 0.53; 95% CI: 0.4-0.69) or after (HR: 0.64; 95% CI: 0.43-0.95) TACE treatment. The combined pre- and postoperative AAPR showed much better performance in ROC curve (1-, 3-, and 5-year AUCs: 0.69, 0.71, 0.69), C-index (0.65; 95% CI: 0.59-0.72) and AIC analyses than pre-AAPR and post-AAPR alone or liver function assessment systems.

CONCLUSION

This study demonstrated both preoperative and postoperative AAPR were independent prognostic factors for HCC patients undergoing TACE. In addition, the combined pre- and post-AAPR showed better predictive performance than pre-AAPR and post-AAPR alone or liver function assessment systems.

Two decades of capacity building to support global malaria control and elimination: retrospective and prospective international trainings in Jiangsu Institute of Parasitic Diseases, China, 2002-2021

BACKGROUND

Malaria is still one of the major infectious diseases affecting human health, and the World Health Organization (WHO) has attached special importance to malaria-related technical training for its global elimination efforts. The Jiangsu Institute of Parasitic Diseases (JIPD), designated as a WHO Collaborating Centre for Research and Training on Malaria Elimination, has conducted numerous international malaria training programmes during the last 2 decades.

METHODS

A retrospective analysis of international training programmes organized and facilitated by JIPD in China since 2002 was conducted. A web-based questionnaire was designed to gather respondents' basic information, evaluation of course topics, methodology, trainers, and facilitators, course impact, and suggestions for future trainings. Individuals who participated in the training courses from 2017 to 2019 were invited to participate in this assessment.

RESULTS

Since 2002, JIPD has conducted 62 malaria-related international trainings attended by 1935 participants from 85 countries, covering 73% of malaria endemic countries. Of 752 participants enrolled, 170 responded to the online survey. A majority of respondents (160/170, 94.12%) gave a high evaluation of the training, with an average score of 4.52 (5 maximum score). Also, survey respondents gave a 4.28 score on "knowledge and skills gained in the training useful for the national malaria programme", 4.52 on "topics appropriate to their professional needs", and 4.52 on "knowledge and skills gained in the training useful to their career". Surveillance and response was the most important topic discussed and field visit was the most effective method of training. For future training programmes, with increasing length of training, more field visits and demonstration, improving language barrier, and sharing experience were what the respondents requested most.

CONCLUSION

JIPD, as a professional institute for malaria control, has conducted a great quantity of training in the past 20 years, providing training opportunities to both malaria and non-malaria endemic countries globally. For future training, survey respondents' suggestions will be considered to provide a more effective capacity building activity to better contribute to global malaria elimination.

Using social media for health education and promotion: a pilot of WeChat-based prize quizzes on China national malaria day

BACKGROUND

Imported malaria cases remains a key health concern, especially during the COVID-19 pandemic. Providing accurate health information is important to improving people's awareness of malaria. WeChat is an excellent social media tool for health information dissemination, especially during the pandemic. This study explored the effect of malaria knowledge dissemination via a WeChat public account.

METHODS

A questionnaire for data collection was constructed using the online survey tool Sojump. Questionnaires were sent to users who followed the Jiangsu institute of Parasitic Disease WeChat public account during the National Malaria Day 2021 period. A small incentive (WeChat Red Packet) was distributed to everyone who answered the questionnaire correctly on time.

RESULTS

A total of 13,169 valid questionnaires were collected during the China National Malaria Day period. Questions in which participants focused mainly on information pertaining to themselves, such as infection, symptoms, and epidemic areas, reached highest accuracy (above 90%). Questionnaires were submitted through smartphones and most of them were completed during the period of 4 days from April 23 to April 26, 2021 when a WeChat Red Packet was offered. The accuracy of responses was related to bolded words and location and number of knowledge points that were shown at the beginning of the questionnaire. The number of users of the WeChat public account in question increased from 5961 to 12,339 in just 4 days of the activity.

CONCLUSION

A WeChat public account is a convenient and accessible tool for spreading malaria-related health information to the public. Distribution of incentives (Red Packets) can effectively increase public attention to popular science and health information and activities.

[Surveillance of Aedes populations in Jiangsu Province in 2020]

OBJECTIVE

To investigate the seasonal Aedes population fluctuation and the resistance of Aedes populations to common insecticides in Jiangsu Province in 2020, so as to provide insights into vector-borne infectious diseases control.

METHODS

One village was randomly sampled from each of Xinbei District of Changzhou City and Zhangjiagang County of Suzhou City in southern Jiangsu Province, Hai'an County of Nantong City and Yandu District of Yancheng City in Central Jiangsu Province, and Suining County of Xuzhou City and Sihong County of Suqian City in northern Jiangsu Province during the period between May and October, 2020. A small ponding container was sampled, and larval Aedes mosquitoes were collected using straws once each in early and late stages of each month. All larvae were bred in laboratory to adults for population identification. In addition, larval breeding were observed in all small ponding containers in and out of 30 households that were randomly sampled from six surveillance sites, and the larval mosquito density was estimated using Breteau index. Larval A. albopictus mosquitoes were sampled around Cuiyuan New Village in Jintan District of Changzhou City, and bred in laboratory to the first offspring generation, and the susceptibility of adult female mosquitoes to deltamethrin, lambda-cyhalothrin, malathion, and propoxur was tested using the filter-paper bioassay recommended by WHO.

RESULTS

A total of 1 165 larval Aedes mosquitoes were captured from small ponding containers in six surveillance sites of Jiangsu Province in 2020, and all were identified as A. albopictus following eclosion. The largest number of Aedes larvae captured was found in July. A total of 1 152 households were investigated in six surveillance sites, and the mean Breteau indexes were 9.58, 13.20, 13.71, 13.20, 12.18 and 5.58 from May to October, respectively, while a high Aedes transmission risk was seen in Xinbei District of Changzhou City, with a higher Breteau index than in Suining (H = 23.667, P_adjusted = 0.001) and Sihong (H = 22.500, P_adjusted = 0.003) counties. The field-captured A. albopictus from Cuiyuan New Village in Jintan District of Changzhou City remained sensitive to malathion, but was resistant to propoxur, and developed high-level resistance to deltamethrin and lambda-cyhalothrin.

CONCLUSIONS

A. albopictus was present in southern, central and northern Jiangsu Province in 2020, and the larval density peaked in July. A. albopictus captured from Cuiyuan New Village in Jintan District of Changzhou City has developed high-level resistance to pyrethroid pesticides.

Extracellular vesicles derived from mesenchymal stem cells confer protection against intervertebral disc degeneration through a microRNA-217-dependent mechanism

OBJECTIVE

Extracellular vesicles released by mesenchymal stem cells (MSC-EVs) can be applied to alleviate intervertebral disc degeneration (IVDD) by curbing apoptosis of nucleus pulposus cells (NPCs). The current study aims to evaluate the effect of MSC-EVs on NPC apoptosis and IVDD and the related regulatory mechanisms involving microRNA (miR)-217.

METHOD

Expression of miR-217 was examined in tumor necrosis factor-α (TNF-α)-induced NPCs and MSC-EVs, followed by identification in the relationship between miR-217, enhancer of zeste homolog 2 (EZH2) and forkhead box O-3 (FOXO3). After isolation of EVs from MSCs and subsequent co-culture with NPCs, we assessed effects of miR-217 on NPC viability, autophagy, senescence and apoptosis along with extracellular matrix (ECM) degradation. Further in vivo experiments were conducted in rat models of IVDD to substantiate the effect of miR-217 on IVDD.

RESULTS

Poor miR-217 expression was found in TNF-α-induced NPCs, while high miR-217 expression was identified in MSC-EVs (P < 0.05). MSC-EVs transferred miR-217 to NPCs and increased its expression, thus attenuating NPC apoptosis and ECM degradation (elevated collagen II and aggrecan but reduced MMP13 and ADAMTS5) (P < 0.05). miR-217 targeted EZH2, and EZH2 bound to the FOXO3 promoter and consequently downregulated its expression. FOXO3 restrained NPC apoptosis and ECM degradation by stimulating cell autophagy (P < 0.05). Furthermore, in vivo experimental results confirmed the suppressive role of miR-217 shuttled by MSC-EVs in IVDD.

CONCLUSION

Overall, the delivery of miR-217 may be a novel mechanism underlying the effect of MSC-EVs on NPC apoptosis and ECM degradation following IVDD.

Melanoma in women of childbearing age and in pregnancy in California, 1994-2015: a population-based cohort study

BACKGROUND

Melanoma is one of the most common malignancies during pregnancy. There is debate regarding the impact of pregnancy on the prognosis of melanoma. Recent large population-based studies from the United States are lacking.

OBJECTIVES

To determine the characteristics and survival of women with pregnancy-associated melanoma.

METHODS

This population-based, retrospective cohort study used California Cancer Registry data linked with state-wide hospitalization and ambulatory surgery data to identify 15-44-year-old female patients diagnosed with melanoma in 1994-2015, including pregnant patients. Multivariable logistic regression compared demographic and clinical characteristics between pregnant and non-pregnant women with melanoma. Multivariable cox proportional hazards regression models assessed melanoma-specific and overall survival.

RESULTS

We identified 13 108 patients, of which 1406 were pregnant. Pregnancy-associated melanoma was more frequent in Hispanic compared to non-Hispanic White women. Melanoma occurring post-partum was associated with greater tumour thickness (2.01-4.00 vs. 0.01-1.00 mm, odds ratio 1.75, 95% confidence interval: 1.03-2.98). There were otherwise no significant differences between pregnant and non-pregnant women. Worse survival was associated with Asian, Black and Native American race/ethnicity (vs. non-Hispanic White), lower neighbourhood socio-economic status, public insurance, tumour site, greater tumour thickness and lymph node involvement, but not pregnancy.

CONCLUSIONS

Melanoma occurring post-partum was associated with greater tumour thickness, but pregnancy status did not affect survival after melanoma. Race/ethnicity, socio-economic status and health insurance impacted survival, emphasizing the importance of reducing health disparities.

Detection of Early Ischemic Changes with Virtual Noncontrast Dual-Energy CT in Acute Ischemic Stroke: A Noninferiority Analysis

BACKGROUND AND PURPOSE

Dual-energy virtual NCCT has the potential to replace conventional NCCT to detect early ischemic changes in acute ischemic stroke. In this study, we evaluated whether virtual NCCT is noninferior compared with standard linearly blended NCCT, a surrogate of conventional NCCT, regarding the detection of early ischemic changes with ASPECTS.

MATERIALS AND METHODS

Adult patients who presented with suspected acute ischemic stroke and who underwent dual-energy NCCT and CTA and brain MR imaging within 48 hours were included. Standard linearly blended images were reconstructed to match a conventional NCCT. Virtual NCCT images were reconstructed from CTA. ASPECTS was evaluated on conventional NCCT, virtual NCCT, and DWI, which served as the reference standard. Agreement between CT assessments and the reference standard was evaluated with the Lin concordance correlation coefficient. Noninferiority was assessed with bootstrapped estimates of the differences in ASPECTS between conventional and virtual NCCT with 95% CIs.

RESULTS

Of the 193 included patients, 100 patients (52%) had ischemia on DWI. Compared with the reference standard, the ASPECTS concordance correlation coefficient for conventional and virtual NCCT was 0.23 (95% CI, 0.15-0.32) and 0.44 (95% CI, 0.33-0.53), respectively. The difference in the concordance correlation coefficient between virtual and conventional NCCT was 0.20 (95% CI, 0.01-0.39) and did not cross the prespecified noninferiority margin of -0.10.

CONCLUSIONS

Dual-energy virtual NCCT is noninferior compared with conventional NCCT for the detection of early ischemic changes with ASPECTS.

Scintillation light detection in the 6-m drift-length ProtoDUNE Dual Phase liquid argon TPC

DUNE is a dual-site experiment for long-baseline neutrino oscillation studies, neutrino astrophysics and nucleon decay searches. ProtoDUNE Dual Phase (DP) is a 6  ×  6  ×  6 m 3 liquid argon time-projection-chamber (LArTPC) that recorded cosmic-muon data at the CERN Neutrino Platform in 2019-2020 as a prototype of the DUNE Far Detector. Charged particles propagating through the LArTPC produce ionization and scintillation light. The scintillation light signal in these detectors can provide the trigger for non-beam events. In addition, it adds precise timing capabilities and improves the calorimetry measurements. In ProtoDUNE-DP, scintillation and electroluminescence light produced by cosmic muons in the LArTPC is collected by photomultiplier tubes placed up to 7 m away from the ionizing track. In this paper, the ProtoDUNE-DP photon detection system performance is evaluated with a particular focus on the different wavelength shifters, such as PEN and TPB, and the use of Xe-doped LAr, considering its future use in giant LArTPCs. The scintillation light production and propagation processes are analyzed and a comparison of simulation to data is performed, improving understanding of the liquid argon properties.

Care-seeking delay of imported malaria to China: implications for improving post-travel healthcare for migrant workers

BACKGROUND

Imported malaria cases continue to pose major challenges in China as well as in other countries having achieved elimination. Our study aims to identify the factors influencing the timing of care-seeking after symptom onset among migrant workers with imported malaria, in order to develop innovative interventions to improve access and provision of post-travel healthcare for returning migrants.

METHODS

We analysed the timing and types of healthcare service utilization after symptom onset among patients with imported malaria between 2012 and 2019 in Jiangsu Province, China. Moreover, decision tree models were used to explore the factors influencing the care-seeking timing after symptom onset among patients with imported malaria.

RESULTS

A total of 2255 cases of imported malaria were identified from 1 June 2012 through 31 December 2019. Patients with malaria imported into China were mainly male migrant labourers returning from sub-Saharan Africa (96.8%). A substantial number of patients with imported malaria sought healthcare >3 days after symptom onset, which clearly represented delayed healthcare-seeking behaviour. According to the decision tree analysis, initial healthcare seeking from healthcare facilities at higher administrative levels, infection with Plasmodium vivax and absence of malaria infection history were significantly associated with delayed healthcare seeking in patients with imported malaria.

CONCLUSION

The delay in seeking of medical care among migrant workers with imported malaria should be considered and addressed by specific interventions. In addition to increasing awareness about these issues among health care professionals, improved access to healthcare facilities at higher administrative levels as well as improved diagnostic capacity of healthcare facilities at lower administrative levels should be developed. Moreover, education programs targeting populations at risk of malaria importation and delayed healthcare seeking should be improved to facilitate early healthcare seeking and service use.

Implementation and challenges to preventing the re-establishment of malaria in China in the COVID-19 era

BACKGROUND

The rapid emergence and global spread of COVID-19 have caused substantial global disruptions that have impacted malaria programs worldwide. Innovative strategies to enable countries aiming to eliminate malaria as well as those that are already certified as malaria-free, are needed to address malaria importation in the context of the COVID-19 pandemic. China was certified as malaria-free in 2021 and now aims to prevent the malaria re-establishment. Nonpharmaceutical interventions such as entry screening, quarantining, and health education for individuals returning from international travel during the COVID-19 pandemic present both opportunities and challenges to the management of imported malaria. This study aimed to describe and analyze the operational challenges associated with an integrated surveillance and case management program in which malaria re-establishment prevention measures were incorporated into the COVID-19 program in China.

METHODS

After the integration of malaria re-establishment prevention activities into the COVID-19 program for 10 months in Jiangsu Province, China, a focus-group discussion of public health workers working on preventing malaria re-establishment and controlling COVID-19 was held in June 2021, aiming to explore the operational challenges and lessons learned from the integrated approach.

RESULTS

From 01 August 2020 to 31 May 2021, 8,947 overseas travelers with Yangzhou as the final destination underwent 14-day managed quarantine and 14-day home isolation. Of these travelers, 5,562 were from malaria-endemic regions. A total of 26,026 education booklets and materials were distributed to expand malaria-related knowledge. Twenty-two patients with unknown fever were screened for malaria with rapid diagnostic tests, and one patient was confirmed to have imported malaria. The challenges associated with the implementation of the integrated malaria surveillance and case management program include neglect of malaria due to COVID-19, lack of a standard operating procedure for malaria screening, mobility of public health providers, and difficulties in respecting the timeline of the "1-3-7" surveillance strategy.

CONCLUSIONS

China's experience highlights the feasibility of integrated case surveillance and management of existing infectious diseases and new emerging infections. It also demonstrates the importance of a sound public health infrastructure with adequate, trained field staff for screening, testing, contact tracing, and providing health education, all of which are crucial for the success of both malaria re-establishment prevention program and the effective control of COVID-19.

AB0864 A nomogram model combining inflammatory factors and MRI radiomics to assess the disease activity of the patients with axSpA in a prospective study

Background

Clinical and magnetic resonance imaging (MRI) disease activity score (DAS) are measuring different aspects of axial spondyloarthritis (axSpA), they are essential in disease activity assessment. The radiomics was on facilitating readings by clinical specialists via enhancing the medical images in which subtle data differences could be distinguished.

Objectives

If the additional information of MRI imaging can be considered as a predictor for axSpA disease activity? In this study, we sought to construct a nomogram integrating the sacroiliac joint (SIJ)- MRI radiomics features and the inflammatory biomarkers to assess disease activity and compare it with clinical disease acitivity index in axSpA patients.

Methods

203 patients data were collected prospectively and confirmed as axSpA were randomly divided into training (n = 143) and validation cohorts (n = 60). 1316 radiomics features were extracted from the 3.0T SIJ-MRI. A Nomogram model was constructed using multivariate logistic regression analysis Incorporating independent clinical factors and radiomics features score (Rad-score). The performance of clinics, Rad-score and nomogram models were evaluated by ROC analysis, calibration curve and decision curve analysis (DCA), and compared with the disease activity index(Ankylosing Spondylitis DAS (ASDAS)-C reactive protein (CRP), ASDAS-erythrocyte sedimentation rate (ESR), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI)) and Spondyloarthritis Research Consortium of Canada (SPARCC) MRI scoring system.

Results

The Rad-score allowed a good discrimination in the training (AUC, 0.91; 95% CI, 0.85-0.96) and the validation cohort (AUC, 0.84; 95% CI, 0.73-0.96). The CRP-radiomics nomogram model also showed favorable discrimination in the training (AUC, 0.96; 95% CI, 0.93-0.99) and the validation cohort (AUC, 0.89; 95% CI, 0.80-0.98), better than BASDAI(AUC, 0.58), ASDAS-CRP(AUC, 0.72), ASDAS-ESR(AUC, 0.77), ESR(AUC, 0.72), CRP(AUC, 0.77) and BASFI(AUC, 0.73), had no statistical difference with SPARCC(AUC, 0.87). Calibration curves and DCA demonstrated the nomogram fit well (p > 0.05) and was useful for activity evaluation.

Conclusion

Rad-score showed good discriminative ability to assess disease activity in axSpA. The nomogram can increase the efficacy for assessment axSpA disease activity, which might simplify clinical evaluation.

Figure 1.

Comparison of ROC curve analyses in prediction models. ROC curves of the clinical features (green curve), radiomics signature model (blue curve), and hybrid model (gold curve) of axSpA in the training cohort (A) and validation cohort (B), respectively. In addition, there are AUC of ASDAS-CRP(pink curve), ASDAS-ESR(brown curve), BASDAI(purple curve), BASFI(azure curve) and SPARCC scoring system(yellow curve) in the validation cohort (B), respectively. AUC: area under the curve; ROC: receiver operating characteristic; SPARCC: Spondyloarthritis Research Consortium of Canada; BASDAI: Bath Ankylosing Spondylitis Disease Activity Index; ASDAS: Ankylosing Spondylitis Disease Activity Score; CRP: C reactive protein; ESR: erythrocyte sedimentation rate; BASFI: Bath Ankylosing Spondylitis Disease Activity Index.

References

[1]Lee KH, Choi ST, Lee GY, Ha YJ, Choi SI. Method for Diagnosing the Bone Marrow Edema of Sacroiliac Joint in Patients with Axial Spondyloarthritis Using Magnetic Resonance Image Analysis Based on Deep Learning. Diagnostics (Basel). 2021;11(7).

[2]Zheng Q, Liu W, Huang Y, Gao Z, Wu Y, Wang X, et al. Predictive Value of Active Sacroiliitis in MRI for Flare Among Chinese Patients with Axial Spondyloarthritis in Remission. Rheumatol Ther. 2021;8(1):411-24.

Acknowledgements

No conflict of interest

Disclosure of Interests

None declared

POS0962 CAN RADIOMICS REPLACE SPARCC SCORING SYSTEM IN EVALUATING BONE MARROW OEDEMA OF THE SACROILIAC JOINTS IN AXIAL SPONDYLOARTHRITIS?

Background

Bone marrow oedema (BMO) of the sacroiliac joints (SIJs) is evaluated to diagnose, classify and monitor disease activity in patients with axial spondyloarthritis (axSpA). Available quantitative methodologies rely on human visual assessment, and errors can’t be completely avoided. Radiomics can extract and select discriminative and quantified features from regions of interest (ROIs), making a more accurate and objective description of BMO.

Objectives

To develop a more objective and efficient method based on radiomics to evaluate BMO of the SIJs by magnetic resonance imaging (MRI) in patients with axSpA in comparison with Spondyloarthritis Research Consortium of Canada (SPARCC) scoring system.

Methods

From September 2013 to July 2021, 523 patients with axSpA underwent 3.0T SIJ-MRI were included, who were randomly classified as training cohort(n=367) and validation cohort(n=156). The optimal radiomics features, selected from the 3.0T SIJ-MRI in the training cohort, were included to build the radiomics model. Four clinical risk predictors were adopted to build the clinical model. The performance of the clinical and radiomics models was evaluated by ROC analysis and decision curve analysis (DCA). Rad-scores were calculated by the radiomics model and SPARCC scores were performed to quantify the BMO of SIJs. We also assessed the correlation between Rad-score and SPARCC score.

Results

The radiomics model, built by 15 optimal features, showed favorable discrimination about SPARCC score <2 or ≥2 both in the training (AUC, 0.91; 95% CI: 0.88-0.94) and the validation cohort (AUC, 0.89; 95% CI, 0.84-0.94). DCA confirmed that the radiomics model was clinically useful. Furthermore, Rad-score has significant correlation with SPARCC score for scoring the status of BMO (rs=0.78, P< 0.001), and moderation correlation for scoring the change (r=0.40, P=0.005).

Conclusion

The radiomics can accurately assess the BMO of the SIJs in axSpA, providing an alternative to SPARCC scoring system. There was a positive correlation between Rad-score and SPARCC score.

References

[1]van der Heijde D, Sieper J, Maksymowych WP, Lambert RG, Chen S, Hojnik M, et al. Clinical and MRI remission in patients with nonradiographic axial spondyloarthritis who received long-term open-label adalimumab treatment: 3-year results of the ABILITY-1 trial. Arthritis Res Ther. 2018;20(1):61.

[2]Landewé RB, Hermann KG, van der Heijde DM, Baraliakos X, Jurik AG, Lambert RG, et al. Scoring sacroiliac joints by magnetic resonance imaging. A multiple-reader reliability experiment. The Journal of rheumatology. 2005;32(10):2050-5.

[3]Cereser L, Zabotti A, Zancan G, Quartuccio L, Cicciò C, Giovannini I, et al. Magnetic resonance imaging assessment of ASAS-defined active sacroiliitis in patients with inflammatory back pain and suspected axial spondyloarthritis: a study of reliability. Clinical and experimental rheumatology. 2021.

[4]Maksymowych WP, Inman RD, Salonen D, Dhillon SS, Williams M, Stone M, et al. Spondyloarthritis research Consortium of Canada magnetic resonance imaging index for assessment of sacroiliac joint inflammation in ankylosing spondylitis. Arthritis Rheum. 2005;53(5):703-9.

[5]Gillies RJ, Kinahan PE, Hricak H. Radiomics: Images Are More than Pictures, They Are Data. Radiology. 2016;278(2):563-77.

Table 1.

Rad-scores corresponding to different SPARCC score intervals about the status of SIJ-BMO.

SPARCC scorenRad-scoreMean(sd)Median (iqr)Range0-1170-1.31(1.64)-1.39(2.16)-6.46, 2.352-61250.73(1.86)0.62(2.12)-3.08, 8.487-11552.25(1.80)2.36(1.79)-1.17, 8.3612-16432.65(2.14)2.66(3.21)-0.76, 7.3917-21383.31(2.05)3.25(2.88)-0.88, 7.5522-26263.08(1.55)3.38(2.12)-1.00, 5.3827-31253.77(1.36)3.77(1.59)0.40, 6.27>31414.10(1.51)4.32(2.28)1.00, 6.96

Disclosure of Interests

None declared

Differential metabolome responses to deltamethrin between resistant and susceptible Anopheles sinensis

Insecticide-based vector control measures play an important role in the prevention and control of insect-borne infectious diseases such as malaria; however, insecticide resistance has become a severe global problem for vector control. To date, the metabolic mechanism by which Anopheles sinensis, the most widely distributed malaria vector in China and Asia, detoxifies insecticides is not clear. In this study, the molecular metabolite changes in both the larval and adult stages of deltamethrin susceptible (DS) and deltamethrin-resistant (DR) An. sinensis mosquitoes were analysed by using liquid chromatography tandem mass spectrometry (LC-MS/MS) after exposure to deltamethrin. There were 127 differential metabolites in larval DR An. sinensis and 168 in adults. Five metabolites (glycerophosphocholine, deoxyguanosine, DL-methionine sulfoxide, D-myo-inositol-3-phosphate and N-acetyl-alpha-D-glucosamine1-phosphate) were downregulated in both DR larvae and adults, and one metabolite (aspartyl-glutamine) was upregulated, and the ratio of down- and up-regulation of these metabolites was 5:1. The differential metabolites between the DS and DR mosquitos were mainly classified into organic oxygen compounds, carboxylic acids and their derivatives, glycerophospholipids and purine nucleotides, and the common pathway enriched in both the larval and adult DR An. sinensis was glycerophospholipid metabolism. The findings of this study provide further mechanistic understanding of insecticide resistance in An. sinensis.

Case-based malaria surveillance and response: implementation of 1-3-7 approach in Jiangsu Province, China

Following initiation of China's National Malaria Elimination Action Plan (NMEAP) in 2010, China's 1-3-7 surveillance and response approach was developed and rolled out in China to facilitate the malaria control programme and accelerate the progress of malaria elimination. Innovative strategies and interventions have been developed and implemented in Jiangsu Province to facilitate case-based malaria surveillance and response. A total of 9879 malaria cases were reported in Jiangsu Province from 2001 to 2020. Since 2012, no indigenous malaria cases have been reported in Jiangsu Province. However, in recent years, there has been a substantial increase of imported cases from abroad. To continue improving the malaria surveillance and response system, Jiangsu Province has conducted population-based health education to improve the healthcare seeking behaviour of malaria patients, strengthened the capacity of health facilities to improve the performance of malaria diagnosis and treatment, and strengthened health workforce capacity to improve the implementation of 1-3-7 approach. Continually improving surveillance and response system can play a critical role in the early detection and rapid response of individual malaria cases and prevent the re-establishment of malaria.

Improving the surveillance and response system to achieve and maintain malaria elimination: a retrospective analysis in Jiangsu Province, China

Background

Following initiation of China’s National Malaria Elimination Action Plan (NMEAP) in 2010, the ‘1-3-7’ approach was developed and rolled out in China to facilitate the malaria elimination programme and accelerate malaria elimination. This study aims to summarize and condense these experiences through a retrospective analysis in Jiangsu Province, which could be adapted and applied in other malaria elimination settings worldwide.

Methods

A retrospective analysis of imported malaria cases into China identified through an improved surveillance and response system in Jiangsu Province was carried out for the period of 2001–2020. To improve the malaria surveillance and response system, Centers for Diseases Control and Prevention from the prefectures and counties in Jiangsu province conducted population-level health education to improve healthcare seeking behavior, strengthened capacity of health facilities to improve performance of malaria diagnosis and treatment, and raised the capacity of public health providers to improve implementation of the ‘1-3-7’ approach. Categorical variables were carried out by Chi square tests with Fisher’s exact correction.

Results

From 2001 to 2020, a total of 9,879 malaria cases were reported in Jiangsu Province. Since 2012, no indigenous malaria cases have been reported in Jiangsu Province. However, in recent years, there has been a substantial increase of imported falciparum malaria cases. Between 2012 and 2020, an estimated 61.57 million individuals have benefited from population-level health education in Jiangsu Province. For healthcare-seeking services among the 2,423 imported malaria cases, 687 (28.4%) and 1,104 (45.6%) cases visited hospitals on the first day and the second day from symptom onset, respectively. A total of 1,502 (61.9%) cases were diagnosed on the first day at medical facilities. Jiangsu Province achieved 100%, 99.4% and 98.3% completion rate in terms of case detection and notification (within one day), case investigation (within three days) and foci response and disposition (within seven days), respectively. The improved surveillance and response system in Jiangsu Province plays an important role in preventing the re-introduction of malaria and maintaining the malaria-free status.

Conclusions

Jiangsu Province has maintained its malaria-free status since 2012. The continuous improvement of a surveillance and response system plays an important role in the early detection and rapid response of potential malaria-related outbreaks in Jiangsu, China, and has important lessons for other malaria eliminating settings. Remaining vigilant in the detection of imported malaria cases and maintaining an active surveillance and response system is critical to sustain the success of malaria elimination.

Graphic Abstract

Impact Analysis of Different CT Configurations of Carotid Artery Plaque Calcifications on Cerebrovascular Events

BACKGROUND AND PURPOSE

CT is considered the standard reference both for quantification and characterization of carotid artery calcifications. Our aim was to investigate the relationship among different types of calcium configurations detected with CT within the plaque with a novel classification and to investigate the prevalence of cerebrovascular events.

MATERIALS AND METHODS

Seven hundred ninety patients (men = 332; mean age, 69.7 [SD, 13] years; 508 symptomatic for cerebrovascular symptoms and 282 asymptomatic) who underwent computed tomography of the carotid arteries were retrospectively included in this institutional review board-approved study. The plaque was classified into 6 types according to the different types of calcium configurations as the following: type 1, complete absence of calcification within the plaque; type 2, intimal or superficial calcifications; type 3, deep or bulky calcifications; type 4, adventitial calcifications with internal soft plaque of <2 mm thickness; type 5, mixed patterns with intimal and bulky calcifications; and type 6, positive rim sign.

RESULTS

The highest prevalence of cerebrovascular events was observed for type 6, for which 89 of the 99 cases were symptomatic. Type 6 plaque had the highest degree of correlation with TIA, stroke, symptoms, and ipsilateral infarct for both sides with a higher prevalence in younger patients. The frequency of symptoms observed by configuration type significantly differed between right and left plaques, with symptoms observed more frequently in type 6 calcification on the right side (50/53; 94%) than on the left side (39/46; 85%, P < .001).

CONCLUSIONS

We propose a novel carotid artery plaque configuration classification that is associated with the prevalence of cerebrovascular events. If confirmed in longitudinal analysis, this classification could be used to stratify the risk of occurrence of ischemic events.

OUP accepted manuscript

Heterochromatin-associated gene silencing controls multiple physiological processes in malaria parasites, however, little is known concerning the regulatory network and cis-acting sequences involved in the organization of heterochromatin and how they modulate heterochromatic gene expression. Based on systematic profiling of genome-wide occupancy of eighteen Apicomplexan AP2 transcription factors by ChIP-seq analysis, we identify and characterize eight heterochromatin-associated factors (PfAP2-HFs), which exhibit preferential enrichment within heterochromatic regions but with differential coverage profiles. Although these ApiAP2s target euchromatic gene loci via specific DNA motifs, they are likely integral components of heterochromatin independent of DNA motif recognition. Systematic knockout screenings of ApiAP2 factors coupled with RNA-seq transcriptomic profiling revealed three activators and three repressors of heterochromatic gene expression including four PfAP2-HFs. Notably, expression of virulence genes is either completely silenced or significantly reduced upon the depletion of PfAP2-HC. Integrated multi-omics analyses reveal autoregulation and feed-forward loops to be common features of the ApiAP2 regulatory network, in addition to the occurrence of dynamic interplay between local chromatin structure and ApiAP2s in transcriptional control. Collectively, this study provides a valuable resource describing the genome-wide landscape of the ApiAP2 family and insights into functional divergence and cooperation within this family during the blood-stage development of malaria parasites.

Genetic diversity and immunogenicity of the merozoite surface protein 1 C-terminal 19-kDa fragment of Plasmodium ovale imported from Africa into China

Background

Merozoite surface protein 1 (MSP1) plays an essential role in erythrocyte invasion by malaria parasites. The C-terminal 19-kDa region of MSP1 has long been considered one of the major candidate antigens for a malaria blood-stage vaccine against Plasmodium falciparum. However, there is limited information on the C-terminal 19-kDa region of Plasmodium ovale MSP1 (PoMSP1₁₉). This study aims to analyze the genetic diversity and immunogenicity of PoMSP1₁₉.

Methods

A total of 37 clinical Plasmodium ovale isolates including Plasmodium ovale curtisi and Plasmodium ovale wallikeri imported from Africa into China and collected during the period 2012–2016 were used. Genomic DNA was used to amplify P. ovale curtisi (poc) msp1₁₉ (pocmsp1₁₉) and P. ovale wallikeri (pow) msp1₁₉ (powmsp1₁₉) genes by polymerase chain reaction. The genetic diversity of pomsp1₁₉ was analyzed using the GeneDoc version 6 programs. Recombinant PoMSP1₁₉ (rPoMSP1₁₉)-glutathione S-transferase (GST) proteins were expressed in an Escherichia coli expression system and analyzed by western blot. Immune responses in BALB/c mice immunized with rPoMSP1₁₉-GST were determined using enzyme-linked immunosorbent assay. In addition, antigen-specific T cell responses were assessed by lymphocyte proliferation assays. A total of 49 serum samples from healthy individuals and individuals infected with P. ovale were used for the evaluation of natural immune responses by using protein microarrays.

Results

Sequences of pomsp1₁₉ were found to be thoroughly conserved in all the clinical isolates. rPoMSP1₁₉ proteins were efficiently expressed and purified as ~ 37-kDa proteins. High antibody responses in mice immunized with rPoMSP1₁₉-GST were observed. rPoMSP1₁₉-GST induced high avidity indexes, with an average of 92.57% and 85.32% for rPocMSP1₁₉ and rPowMSP1₁₉, respectively. Cross-reactivity between rPocMSP1₁₉ and rPowMSP1₁₉ was observed. Cellular immune responses to rPocMSP1₁₉ (69.51%) and rPowMSP1₁₉ (52.17%) induced in rPocMSP1₁₉- and rPowMSP1₁₉-immunized mice were found in the splenocyte proliferation assays. The sensitivity and specificity of rPoMSP1₁₉-GST proteins for the detection of natural immune responses in patients infected with P. ovale were 89.96% and 75%, respectively.

Conclusions

This study revealed highly conserved gene sequences of pomsp1₁₉. In addition, naturally acquired humoral immune responses against rPoMSP1 were observed in P. ovale infections, and high immunogenicity of rPoMSP1₁₉ in mice was also identified. These instructive findings should encourage further testing of PoMSP1₁₉ for rational vaccine design.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-05086-6.

Barriers to seeking health care among returning travellers with malaria: A systematic review

OBJECTIVE

To identify barriers to seeking health care among returning travellers with malaria with the aim of developing targeted interventions that improve early health care-seeking behaviour, diagnosis and treatment.

METHODS

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we conducted a systematic review of published medical literature, selecting studies that investigated and reported barriers to seeking health care among returning travellers and migrants with malaria. In total, 633 articles were screened, of which four studies met the inclusion criteria after a full-text review.

RESULTS

The four studies reported barriers to seeking healthcare among returning travellers in China, the United States, Thailand and the Dominican Republic. Three studies had an observational design. The identified barriers were summarised based on the appraisal delay, illness delay and utilisation delay stages. During appraisal delays, low awareness of malaria was the most significant factor. Once the patient assessed that he or she was ill, belonging to a specific minority ethnicity, being infected with P. vivax and receiving a low level of social support were predictors of delayed health care-seeking. Finally, the most significant factor associated with utilisation delays was the monetary cost.

CONCLUSION

The health care-seeking behaviour of returning travellers with malaria should be further investigated and improved. Addressing the identified barriers and gaps in health care-seeking behaviour among returning travellers with malaria, particularly among groups at high risk of travel-associated infections, is important to prevent severe disease and deaths as well as secondary transmission and epidemics.

Prevalence and molecular characterization of Wolbachia in field-collected Aedes albopictus, Anopheles sinensis, Armigeres subalbatus, Culex pipiens and Cx. tritaeniorhynchus in China

Wolbachia are maternally transmitted intracellular bacteria that can naturally and artificially infect arthropods and nematodes. Recently, they were applied to control the spread of mosquito-borne pathogens by causing cytoplasmic incompatibility (CI) between germ cells of females and males. The ability of Wolbachia to induce CI is based on the prevalence and polymorphism of Wolbachia in natural populations of mosquitoes. In this study, we screened the natural infection level and diversity of Wolbachia in field-collected mosquitoes from 25 provinces of China based on partial sequence of Wolbachia surface protein (wsp) gene and multilocus sequence typing (MLST). Among the samples, 2489 mosquitoes were captured from 24 provinces between July and September, 2014 and the remaining 1025 mosquitoes were collected month-by-month in Yangzhou, Jiangsu province between September 2013 and August 2014. Our results showed that the presence of Wolbachia was observed in mosquitoes of Aedes albopictus (97.1%, 331/341), Armigeres subalbatus (95.8%, 481/502), Culex pipiens (87.0%, 1525/1752), Cx. tritaeniorhynchus (17.1%, 14/82), but not Anopheles sinensis (n = 88). Phylogenetic analysis indicated that high polymorphism of wsp and MLST loci was observed in Ae. albopictus mosquitoes, while no or low polymorphisms were in Ar. subalbatus and Cx. pipiens mosquitoes. A total of 12 unique mutations of deduced amino acid were identified in the wsp sequences obtained in this study, including four mutations in Wolbachia supergroup A and eight mutations in supergroup B. This study revealed the prevalence and polymorphism of Wolbachia in mosquitoes in large-scale regions of China and will provide some useful information when performing Wolbachia-based mosquito biocontrol strategies in China.

The mosquitoes Aedes albopictus, Anopheles sinensis, Armigeres subalbatus, Culex pipiens and Cx. tritaeniorhynchus are native to China and the major vectors in the transmission of arboviruses, protozoans and nematodes. Recently, an innovative biocontrol strategy has been developed and evaluated based on the ability of Wolbachia to induce cytoplasmic incompatibility (CI), as well as interfere with the infection and replication of pathogens. Since the ability to induce CI largely depends on the density and diversity of Wolbachia, we investigated and characterized the natural infection of Wolbachia in above-mentioned five species of field-collected mosquitoes in 25 provinces of China. The results showed that the positive rates of Wolbachia infection were high in mosquitoes of Ae. albopictus, Ar. subalbatus and Cx. pipiens in large-scale regions of China and low in Cx. tritaeniorhynchus in Guizhou province. Phylogenetic analysis based on Wolbachia surface protein (wsp) gene and five multilocus sequence typing (MLST) loci indicated the high polymorphism of Wolbachia in Ae. albopictus, and low polymorphisms in Ar. subalbatus and Cx. pipiens. This finding contributes to the understanding of the nationwide distribution of Wolbachia and the potential application of this biocontrol strategy in China.

Era-like GTP protein gene expression in rice

The mutations are genetic changes in the genome sequences and have a significant role in biotechnology, genetics, and molecular biology even to find out the genome sequences of a cell DNA along with the viral RNA sequencing. The mutations are the alterations in DNA that may be natural or spontaneous and induced due to biochemical reactions or radiations which damage cell DNA. There is another cause of mutations which is known as transposons or jumping genes which can change their position in the genome during meiosis or DNA replication. The transposable elements can induce by self in the genome due to cellular and molecular mechanisms including hypermutation which caused the localization of transposable elements to move within the genome. The use of induced mutations for studying the mutagenesis in crop plants is very common as well as a promising method for screening crop plants with new and enhanced traits for the improvement of yield and production. The utilization of insertional mutations through transposons or jumping genes usually generates stable mutant alleles which are mostly tagged for the presence or absence of jumping genes or transposable elements. The transposable elements may be used for the identification of mutated genes in crop plants and even for the stable insertion of transposable elements in mutated crop plants. The guanine nucleotide-binding (GTP) proteins have an important role in inducing tolerance in rice plants to combat abiotic stress conditions.

Lactobacillus strains derived from human gut ameliorate metabolic disorders via modulation of gut microbiota composition and short-chain fatty acids metabolism

Regulation on gut microbiota and short-chain fatty acids (SCFAs) are believed to be a pathway to suppress the development of metabolic syndrome. In this study, three Lactobacillus strains derived from the human gut were investigated for their effects on alleviation of metabolic disorders. These strains were individually administered to metabolic disorder rats induced by high-fat-high-sucrose (HFHS) diet. Each strain exhibited its own characteristics in attenuating the impaired glucose-insulin homeostasis, hepatic oxidative damage and steatosis. Correlation analysis between SCFAs and host metabolic parameters suggested that Lactobacillus protective effects on metabolic disorders are partly mediated by recovery of SCFAs production, especially the faecal acetic acid. Correspondingly, it indicated that probiotics restore the gut microbiota dysbiosis in different extent, thereby protect against metabolic disorders in a manner that is associated with microbiota, but not totally reverse the changed composition of microbiota to the normal state. Thus, Lactobacillus strains partly protect against diet-induced metabolic syndrome by microbiota modulation and acetate elevation.

Prospects for beyond the Standard Model physics searches at the Deep Underground Neutrino Experiment: DUNE Collaboration

The Deep Underground Neutrino Experiment (DUNE) will be a powerful tool for a variety of physics topics. The high-intensity proton beams provide a large neutrino flux, sampled by a near detector system consisting of a combination of capable precision detectors, and by the massive far detector system located deep underground. This configuration sets up DUNE as a machine for discovery, as it enables opportunities not only to perform precision neutrino measurements that may uncover deviations from the present three-flavor mixing paradigm, but also to discover new particles and unveil new interactions and symmetries beyond those predicted in the Standard Model (SM). Of the many potential beyond the Standard Model (BSM) topics DUNE will probe, this paper presents a selection of studies quantifying DUNE's sensitivities to sterile neutrino mixing, heavy neutral leptons, non-standard interactions, CPT symmetry violation, Lorentz invariance violation, neutrino trident production, dark matter from both beam induced and cosmogenic sources, baryon number violation, and other new physics topics that complement those at high-energy colliders and significantly extend the present reach.

A PCR-Based Technique to Track the Geographic Origin of Plasmodium falciparum With 23-SNP Barcode Analysis

Increased population movement has increased the risk of reintroducing parasites to elimination areas and also dispersing drug-resistant parasites to new regions. Therefore, reliable and repeatable methods to trace back to the source of imported infections are essential. The recently developed 23-single-nucleotide polymorphism (SNP) barcode from organellar genomes of mitochondrion (mt) and apicoplast (apico) provides a valuable tool to locate the geographic origin of Plasmodium falciparum. This study aims to explore the feasibility of using the 23-SNP barcode for tracking P. falciparum by polymerase chain reaction and sequencing, while providing geographical haplotypes of isolates that originated from Central Africa. Based on 23-SNP barcode analysis, SNPs were found at seven loci; 27 isolates were confirmed to have originated in West Africa, and this study also showed four isolates from Central Africa (Equatorial Guinea, 3; Republic of Congo, 1) that originated in East Africa. This study provides the sequence data from Central Africa and fills 23-SNP barcode data gaps of sample origins.

The Microbiota of Three Anopheles Species in China

Microbiota are vital for the development, physiology, and vectorial capacity of mosquitoes. The composition and role of microbiota in Anopheles species, especially Anopheles gambiae and Anopheles stephensi, have been extensively studied, but little is known about the microbiota of Anopheles species in China. We characterized the microbial communities of Anopheles dirus, Anopheles sinensis, and Anopheles lesteri by 16S rRNA sequencing. There were distinct differences in the composition of microbiota in An. lesteri and the other 2 species. The discriminatory genera in the 3 species were analyzed by the linear discriminant analysis effect size method. Our results provide an overview of the population structure of microbiota in 3 native Anopheles species and will pave the way for further understanding of their role in mosquito physiology and vector competence.

Prediction of Clinical Outcome in Patients with Large-Vessel Acute Ischemic Stroke: Performance of Machine Learning versus SPAN-100

BACKGROUND AND PURPOSE

Traditional statistical models and pretreatment scoring systems have been used to predict the outcome for acute ischemic stroke patients (AIS). Our aim was to select the most relevant features in terms of outcome prediction on the basis of machine learning algorithms for patients with acute ischemic stroke and to compare the performance between multiple models and the Stroke Prognostication Using Age and National Institutes of Health Stroke Scale (SPAN-100) index model.

MATERIALS AND METHODS

A retrospective multicenter cohort of 1431 patients with acute ischemic stroke was subdivided into recanalized and nonrecanalized patients. Extreme Gradient Boosting machine learning models were built to predict the mRS score at 90 days using clinical, imaging, combined, and best-performing features. Feature selection was performed using the relative weight and frequency of occurrence in the models. The model with the best performance was compared with the SPAN-100 index model using area under the receiver operating curve analysis.

RESULTS

In 3 groups of patients, the baseline NIHSS was the most significant predictor of outcome among all the parameters, with relative weights of 0.36∼0.69; ischemic core volume on CTP ranked as the most important imaging biomarker with relative weights of 0.29∼0.47. The model with the best-performing features had a better performance than the other machine learning models. The area under the curve of the model with the best-performing features was higher than SPAN-100 model and reached statistical significance for the total (P < .05) and the nonrecanalized patients (P < .001).

CONCLUSIONS

Machine learning-based feature selection can identify parameters with higher performance in outcome prediction. Machine learning models with the best-performing features, especially advanced CTP data, had superior performance of the recovery outcome prediction for patients with stroke at admission in comparison with SPAN-100.

High value of rapid diagnostic tests to diagnose malaria within children: A systematic review and meta-analysis

Background

Children aged under five years accounted for 61% of all malaria deaths worldwide in 2017, and quicker differential diagnosis of malaria fever is vital for them. Rapid diagnostic tests (RDTs) are strips to detect

Plasmodium

specific antigens promptly and are helpful in resource-limited areas. Thus, our aim is to assess the diagnostic accuracy of RDTs for malaria in children against the gold standard.

Methods

MEDLINE, Web of Science, EMBASE, Cochrane Library, the China National Knowledge Infrastructure, Wanfang, and Sinomed databases were systematically searched on August 23, 2019. Studies that compared RDTs with microscopy or polymerase chain reaction in malaria diagnoses for children were eligible. Relevant data were extracted. The quality of studies was evaluated using the revised Quality Assessment of Diagnostic Accuracy Studies instrument. Meta-analyses were carried out to calculate the pooled estimates and 95% confidence intervals of sensitivity and specificity.

Results

51 articles were included. For diagnostic accuracy, the pooled estimates of the sensitivity and specificity of RDTs were 0.93 (95% confidence interval (CI) = 0.90, 0.95) and 0.93 (95% CI = 0.90, 0.96) respectively. Studies were highly heterogeneous, and subgroup analyses showed that the application of RDTs in high malaria transmission areas had higher sensitivity but lower specificity than those in low-to-moderate areas.

Conclusions

RDTs have high accuracy for malaria diagnosis in children, and this characteristic is more prominent in high transmission areas. As they also have the advantages of rapid-detection, are easy-to-use, and can be cost-effective, it is recommended that the wider usage of RDTs should be promoted, especially in resource-limited areas. Further research is required to assess their performance in WHO South-East Asia and Americas Region.

Clinical characteristics and predictors of the duration of SARS-CoV-2 viral shedding in 140 healthcare workers

BACKGROUND

Epidemiological and clinical features of patients with COVID-19 have been reported, but none of them focused on medical staff, and few predictors of the duration of viral shedding have been reported. It is urgent to help healthcare workers prevent and recover quickly from the coronavirus disease 2019 (COVID-19).

METHODS

We enrolled 140 medical workers with COVID-19 in Wuhan. Epidemiological, demographic, clinical, laboratory, radiological treatment and clinical outcome data were collected, and predictors of the duration of viral shedding were explored through multivariable linear regression analysis.

RESULTS

The medical staff with COVID-19 presented mild clinical symptoms and showed a low frequency of abnormal laboratory indicators. All the medical staff were cured and discharged, of whom 96 (68.6%) were female, 39 (27.9%) had underlying diseases, the median age was 36.0 years, and 104 (74.3%) were infected whilst working in hospital. The median duration of viral shedding was 25.0 days (IQR:20.0-30.0). Multivariable linear regression analysis showed reducing viral shedding duration was associated with receiving recombinant human interferon alpha (rIFN-α) treatment, whilst the prolonged duration of viral shedding correlated with the use of glucocorticoid treatment, the durations from the first symptom to hospital admission and the improvement in chest computed tomography (CT) evidence. Moreover, infected healthcare workers with lymphocytes less than 1.1 × 10⁹ /L on admission had prolonged viral shedding.

CONCLUSION

Medical staff with timely medical interventions show milder clinical features. Glucocorticoid treatment and lymphocytes less than 1.1 × 109/L are associated with prolonged viral shedding. Early admission and rIFN-α treatment help shorten the duration of viral shedding.

PHACTR1, a pro-atherosclerotic mechanosensitive PPARgamma corepressor in endothelial cells

Background

Numerous genome-wide association studies revealed that SNPs at phosphatase and actin regulator 1 (PHACTR1) locus are strongly correlated with coronary artery disease (CAD). However, the mechanism linking these variants to CAD remains uncertain.

Purpose

We studied the biological functions and molecular mechanisms of PHACTR1 in atherosclerosis.

Methods and results

Analysis of GTEx database showed that CAD-related SNPs in PHACTR1 are cis-eQTLs for PHACTR1 in arteries. Therefore, we generated Phactr1 knockout mice and crossed them with apolipoprotein E-deficient (ApoE−/−) mice to induce atherosclerosis by high-fat/high-cholesterol (HF-HC) diet. Phactr1 deficiency significantly inhibited atherosclerosis with decreased inflammatory cell infiltration. Western blot showed that PHACTR1 was restricted to endothelial cells (ECs) in mice. Mechanistically, RNAseq of aortic ECs revealed that the major molecular function of PHACTR1 was transcriptional regulation. PPARγ/RXRα was the top transcription factor, and PPARγ target gene expression substantially increased in Phactr1−/− mice. Moreover, we generated endothelial cell specific Phactr1−/−, ApoE−/− mice and found decreased atherosclerotic plaque area in aortic sinus. In vitro, PHACTR1 associated with PPARγ and inhibited PPARγ transcriptional activity. The inhibitory effect of PHACTR1 on PPARγ required its shuttling from cytosol to nucleus triggered by disturbed flow, a well-established pro-atherosclerotic stimulus.

Conclusion

Our results identified PHACTR1 as a mechanosensitive corepressor of PPARγ in ECs to promote atherosclerosis. Endothelial PHACTR1 is a potential therapeutic target for atherosclerosis treatment.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): National Natural Science Foundation of China (NSFC), China Postdoctoral Science Foundation (CPSF)

Low genetic diversity and strong immunogenicity within the apical membrane antigen-1 of plasmodium ovale spp. imported from africa to china

Malaria is still an important challenge for global public health because of its extensive mortality and morbidity. Plasmodium ovale is mainly distributed in tropical regions of Africa and Asia. it includes two distinct ovale malaria species, which are P. ovale curtisi and P. ovale wallikeri. Apical membrane antigen-1 (AMA-1) is an asexual blood-stage protein which is essential for Plasmodium. Thus far, no study on gene polymorphism and immunogenicity of P. ovale AMA-1 (PoAMA-1) has been conducted. Amplified poama1 gene products from 14 P ovale curtisi samples and 12 P ovale wallikeri samples imported from Africa to Jiangsu Province, China were sequenced and their polymorphisms were analyzed. We expressed recombinant PoAMA-1 (rPoAMA-1, 53 kDa) proteins in an E. coli expression system and evaluated immune responses against the rPoAMA-1 in BALB/c mice. We identified a synonymous mutation in nucleotide position 333 of the pocama-1 gene and powama-1 did not reveal any variation. The humoral and cellular immune responses to rPoAMA-1 were evaluated using enzyme-linked immunosorbent assay (ELISA) and flow cytometry. rPoAMA-1-immunized mice produced specific antibodies as verified by immunoblotting. The rPoAMA-1 induced high antibody titers (1: 640,000), and had high avidity indexes (an average of 78.63% and 83.40%). The antibodies also recognized the native proteins, namely, crude antigen from blood stages. Cross-reactivity between rPocAMA-1 and rPowAMA-1 was observed. Moreover, rPoAMA-1 s induced interferon (IFN)-gamma-secreting cells in mice and increased lymphocyte proliferation response. Low genetic diversity was observed in poama-1 from the Jiangsu Province imported malaria cases, and further studies conclusively showed its strong immunogenicity. Significant cross-reactivity was found between rPocAMA-1 and rPowAMA-1, suggesting that a single PoAMA-1 antigen could be used to diagnose P. ovale curtisi or P. ovale wallikeri patient simultaneously. However, further evaluation needs to be carried out to validate the potential and limitations of PoAMA-1 as a candidate vaccine.