Effectiveness of inactivated COVID-19 vaccine CoronaVac in children aged less than 3 years old during Omicron wave in Hong Kong

The COVID-19 pandemic has affected people of all ages worldwide. However, there is still no information on the vaccine effectiveness (VE) of inactivated COVID-19 vaccines in children aged less than 3 years old. This study highlighted that 2 doses of CoronaVac were effective in preventing COVID-19, with a VE of 83.1 %.

Multiplicity of infection of Plasmodium knowlesi in Malaysia: an application of Pkmsp-1 block IV

In Malaysia presently, the main cause of human malaria is by the zoonotic monkey parasite Plasmodium knowlesi. A previous study has suggested that the P. knowlesi merozoite surface protein 1 (Pkmsp-1) block IV to be a suitable multiplicity of infection (MOI) genotyping marker for knowlesimalaria. This study therefore aimed to investigate the usefulness of Pkmsp-1 block IV in assessing the MOI of P. knowlesi in clinical isolates from Malaysia. Two allele-specific PCR primer pairs targeting the two allelic families of block IV (T1 and T2) were designed, and used to genotype P. knowlesi in 200 blood samples (100 from Peninsular Malaysia and 100 from Malaysian Borneo). Results showed that the mean MOI in Malaysian Borneo was slightly higher as compared to Peninsular Malaysia (1.58 and 1.40, respectively). Almost half of the total blood samples from Malaysian Borneo (52%) had polyclonal infections (i.e., more than one allele of any family type) as compared to Peninsular Malaysia (33%) samples. The T1 allelic family was more prevalent in Peninsular Malaysia (n=75) than in Malaysian Borneo (n=60). The T2 allelic family, however, was more prevalent in the Malaysian Borneo (n=87 vs n=53 respectively). This study shows that the single locus Pkmsp-1 block IV can serve as a simple alternative genetic marker for estimating knowlesi malaria MOI in a population. Future MOI studies should focus on macaque populations as macaques are the natural host of P. knowlesi.

Plasmodium knowlesi circumsporozoite protein: genetic characterisation and predicted antigenicity of the central repeat region

Circumsporozoite protein (CSP) central repeat region is one of the main target regions of the RTS,S/AS01 vaccine for falciparum infection as it consists of immunodominant B cell epitopes. However, there is a lack of study for P. knowlesi CSP central repeat region. This study aims to characterise the CSP repeat motifs of P. knowlesi isolates in Peninsular Malaysia. CSP repeat motifs of 64 P. knowlesi isolates were identified using Rapid Automatic Detection and Alignment of Repeats (RADAR). Antigenicity of the repeat motifs and linear B cell epitopes were predicted using VaxiJen 2.0, BepiPred-2.0 and BCPred, respectively. A total of 35 dominant repeat motifs were identified. The repeat motif "AGQPQAQGDGANAGQPQAQGDGAN" has the highest repeat frequency (n=15) and antigenicity index of 1.7986. All the repeat regions were predicted as B cell epitopes. In silico approaches revealed that all repeat motifs were antigenic and consisted of B cell epitopes which could be designed as knowlesi malaria vaccine.

Genetic diversity of secreted protein with an altered thrombospondin repeat (SPATR) of Plasmodium knowlesi clinical isolates from Malaysia

The Plasmodium knowlesi secreted protein with an altered thrombospondin repeat (PkSPATR) is an important protein that helps in the parasite's invasion into the host cell. This protein has been regarded as one of the potential vaccine candidates against P. knowlesi infection. This study investigates the genetic diversity and natural selection of PkSPATR gene of P. knowlesi clinical isolates from Malaysia. PCR amplification of the full length PkSPATR gene was performed on 60 blood samples of infected P. knowlesi patients from Peninsular Malaysia and Malaysian Borneo. The amplified PCR products were cloned and sequenced. Sequence analysis of PkSPATR from Malaysia showed higher nucleotide diversity (CDS p: 0.01462) than previously reported Plasmodium vivax PvSPATR (p = 0.0003). PkSPATR from Peninsular Malaysia was observed to have slightly higher diversity (CDS p: 0.01307) than those from Malaysian Borneo (CDS p: 0.01212). Natural selection analysis on PkSPATR indicated significant purifying selection. Multiple amino acid sequence alignment revealed 69 polymorphic sites. The phylogenetic tree and haplotype network did not show any distinct clustering of PkSPATR. The low genetic diversity level, natural selection and absence of clustering implied functional constrains of the PkSPATR protein.

Molecular survey of head lice (Pediculus humanus capitis) infestation among disadvantaged children in Klang Valley, Malaysia

Ectoparasitic infestations including pediculosis capitis are common in people of disadvantaged communities as they live in overcrowded institutions, a condition that often favourable for disease transmission. In this study, we evaluated the prevalence of head lice infestation among disadvantaged children aged between five to 14 years-old living in five poor conditions located across the Klang Valley, Malaysia. Of total 335 children examined, 14% were positively infected with head lice. Molecular analysis using the universal cytochrome c oxidase subunit I ( COI) barcoding gene on total of 167 head lice collected in this study indicated they are belonging to the A and C clades; confirming the global distribution of clade A and expansion of clade C in Southeast Asia, which is reported for the first time in Malaysia.

Public health status of Myanmar refugees in South East Asia: A Malaysian case study

The United Nations High Commissioner for Refugees (UNHCR) reports over 80 million people are displaced worldwide with approximately 26.3 million categorized as refugees and over a million residing temporarily in South East Asia. Despite the lack of national legislative framework in place for refugees and asylum seekers (RAS), Malaysia hosts approximately 178,140 as registered with UNHCR and the majority originate from Myanmar. In this review, we examine refugees from South East Asia, particularly from Myanmar that have contributed to the largest influx of refugees to this region with a focus on their health status. The present study traces barriers to the health care of refugees in the country of asylum and also the challenges faced by these communities in accessing health services.

Negative impact of socioeconomic deprivation on clinical outcomes after cryoablation for atrial fibrillation: 18-month study

Background

Lower socioeconomic status has also been shown to associate with higher incidence of atrial fibrillation (AF), increased mortality and morbidity. However, the impact of socioeconomic deprivation on clinical outcomes post AF cryoablation has yet to be investigated.

Aim

To assess the impact of socioeconomic deprivation (as categorised by Scottish Index of Multiple Deprivation, SIMD) on the medical management and clinical outcomes of patients with AF post cryoablation.

Methods

A retrospective study of paroxysmal or persistent AF patients after cryoablation. Parameters included basic demographics, weight, past medical history (hypertension, heart failure, diabetes, stroke, myocardial infarction, sleep apnoea) and alcohol misuse. Medical treatment post ablation (Beta blocker, calcium channel blocker, flecainide, amiodarone, dronaderone, sotolol, anticoagulant use) were also recorded.

Socioeconomic deprivation index, as per SIMD was recorded (1 – most deprived and 10 – least deprived), and accordingly placed into quintile (SIMD 1–2,3–4,5–6,7–8, 9–10). Follow-up for 18 months.

Clinical outcome assessed was rate of readmission for symptomatic AF, rate of heart failure admission, stroke, bleeding diathesis and all-cause mortality.

Results

383 patients were identified: 78 from the lowest quintile (SIMD 1–2), 68 (SIMD 3–4), 64 (SIMD 5–6), 62 (SIMD 7–8), and 111 from the highest quintile (SIMD 9–10). No statistical difference exists between age, gender or weight. Lowest socioeconomic quintile has higher incidence of heart failure (p=0.006) and hypertension (p=0.005) but other past medical history was no different. No difference in incidence of alcohol misuse.

Medicine prescription was not different. Echo features: left ventricular function, atrial size and valvular dysfunction were not different between all groups.

18 months follow-up demonstrated that both readmission for symptomatic documented AF and recurrence of symptoms at 18 months were higher among patients of lowest socioeconomic quintile (Keplan Meier plot, p=0.014 and p=0.006 respectively). Stepwise multiple regression analysis also confirmed multiple socioeconomic deprivation as an independent predictor for more adverse clinical outcome (p=0.02).

Risk of symptom recurrence at 18 months in patients from the least deprived background is less than one third as compared to the ones from the most deprived background (Odd-ratio 0.32 (0.17 - 0.59))

Risk of readmission for AF in patients from the wealthiest socioeconomic group is also less than a third as compared to those of most deprived social group (Odd-ratio 0.31 (95% CI 0.15–0.61)).

Other clinical outcomes including risk of admissions for heart failure, stroke, bleeding diathesis and all-cause mortality was not statistically different across all groups.

Summary

After cryoablation, patients from the lowest socioeconomic group are more likely to experience symptoms recurrence and readmission for symptomatic AF

Funding Acknowledgement

Type of funding sources: None.

High incidence of Plasmodium knowlesi malaria compared to other human malaria species in several hospitals in Malaysia

Through the regional control programme, Malaysia has been successfully reducing the incidence of Plasmodium falciparum and Plasmodium vivax infections. However, the incidence of zoonotic malaria Plasmodium knowlesi infection is increasing and now has been the major cause of malaria in Malaysia especially Malaysian Borneo. The emergence of knowlesi infection has threatened the malaria elimination programme which the government aims to reduce the overall malaria infections by 2020. Unlike other benign human Plasmodium spp., P. knowlesi can cause fatal infections. The aim of this study was to determine the incidence and distribution of five human malaria parasites including P. knowlesi in Peninsular Malaysia and Malaysian Borneo. A total of 112 blood samples were collected from seven states and district hospitals in Peninsular Malaysia and Malaysian Borneo from year 2015 to 2016. The samples were examined by microscopy and further confirmed by nested PCR assay targeting 18S rRNA gene of Plasmodium spp. Following the nested PCR assays, a total of 54 (48.2%) samples were positive for P. knowlesi infections, 12 (10.7%) cases were positive for P. vivax infections, followed by 7 (6.3%) cases of P. falciparum and 4 (3.5%) cases of P. malariae. There were 3 cases (2.7%) of mixed infections (P. knowlesi/P. vivax). However, no cases were identified as P. ovale. A total of 32 (28.6%) cases were found as negative infections. LoopMediated Isothermal Amplification Assay (LAMP) was performed to confirm inconclusive results produced by microscopy and nested PCR. P. knowlesi showed the highest prevalence in Sarawak (n= 30), Sabah (n=13), Pulau Pinang (n=5) and Pahang (n=6). PCR and LAMP was not able to detect a large number of microscopy positive samples due to DNA degradation during storage and shipping. Among all the states involved in this study, the highest prevalence of P. knowlesi infection was found in Sabah and Sarawak.

Genetic diversity of the full length apical membrane antigen-1 of Plasmodium knowlesi clinical isolates from Peninsular Malaysia

The Plasmodium knowlesi apical membrane antigen-1 (PkAMA-1) plays an important role in the invasion of the parasite into its host erythrocyte, and it has been regarded as a potential vaccine candidate against human knowlesi malaria. This study investigates genetic diversity and natural selection of the full length PkAMA-1 of P. knowlesi clinical isolates from Peninsular Malaysia. Blood samples were collected from P. knowlesi malaria patients from Peninsular Malaysia. The PkAMA-1 gene was amplified from DNA samples using PCR, cloned into a plasmid vector and sequenced. Results showed that nucleotide diversity of the full length PkAMA-1 from Peninsular Malaysia isolates (π: 0.006) was almost similar to that of Sarawak (π: 0.005) and Sabah (π: 0.004) isolates reported in other studies. Deeper analysis revealed Domain I (π: 0.007) in the PkAMA-1 had the highest diversity as compared to Domain II (π: 0.004) and Domain III (π: 0.003). Z-test indicated negative (purifying) selection of the gene. Combined alignment analysis at the amino acid level for the Peninsular Malaysia and Sarawak PkAMA-1 sequences revealed 34 polymorphic sites. Thirty-one of these sites were dimorphic, and 3 were trimorphic. The amino acid sequences could be categorised into 31 haplotypes. In the haplotype network, PkAMA-1 from Peninsular Malaysia and Sarawak were separated into two groups.

Experimental Study on Plasmodium knowlesi Normocyte Binding Protein Xa Region II (PkNBPXaII) for Erythrocyte Binding

Normocyte binding protein Xa (NBPXa) has been implied to play a significant role in parasite invasion of human erythrocytes. Previous phylogenetic studies have reported the existence of three types of NBPXa for Plasmodium knowlesi (PkNBPXa). PkNBPXa region II (PkNBPXaII) of type 1, type 2 and type 3 were expressed on mammalian cell surface and interacted with human and macaque (Macaca fascicularis) erythrocytes. The binding activities of PkNBPXaII towards human and macaque erythrocytes were evaluated using erythrocyte-binding assay (EBA). Three parameters were evaluated to achieve the optimal protein expression of PkNBPXaII and erythrocyte binding activity in EBA: types of mammalian cells, post transfection time and erythrocyte incubation time. COS-7, HEK-293, and CHO-K1 cells showed successful expression of PkNBPXaII, despite the protein expression is weak compared to the positive control. COS-7 was used in EBA. All three types of PkNBPXaII showed rosette formation with macaque erythrocytes but not with human erythrocytes. Future studies to enhance the PkNBPXaII expression on surface of mammalian cells is indeed needed in order to elucidate the specific role of PkNBPXaII in erythrocytes invasion.

Socioeconomic deprivation and 1 year clinical outcomes after cryablation for atrial fibrillation

Funding Acknowledgements

Type of funding sources: None.

BACKGROUND

Socioeconomic deprivation has previously been demonstrated to result in worse heart failure and myocardial infarction outcomes. Published studies shown lower socioeconomic group to associate with higher prevalence of atrial fibrillation (AF), increased mortality and morbidity. However, the impact of socioeconomic deprivation on clinical outcomes post AF cryoablation has yet to be investigated.

AIM

To assess the impact of socioeconomic deprivation (as categorised by Scottish Index of Multiple Deprivation, SIMD) on the medical management and clinical outcomes of patients with AF treated by cryoablation. 

METHODS

A retrospective study of paroxysmal or persistent AF patients after cryoablation. The parameters included basic demographics, weight, past medical history (inclusive of hypertension, heart failure, diabetes, stroke or transient ischaemic attacks, prior myocardial infarction, obstructive sleep apnoea) and alcohol misuse. Medical treatment post AF ablation (Beta blocker, non-dihydropyridine calcium channel blocker, flecainide, amiodarone, dronaderone, sotolol, anticoagulant use) were also recorded.

Individual’s socioeconomic deprivation index, as described SIMD was also recorded (1 – most deprived and 10 – least deprived), and accordingly placed into quintile (SIMD 1-2,3-4,5-6,7-8, 9-10). Follow-up for 12 months.

Clinical outcome assessed was rate of readmission for symptomatic documented AF, rate of heart failure admission, stroke, bleeding diathesis and all-cause mortality.

RESULTS

312 patients were identified: 65 from the lowest quintile (SIMD 1-2), 57 from SIMD 3-4, 54 from SIMD 5-6, 52 from SIMD 7-8, and 84 from the highest quintile (SIMD 9-10).  No statistical difference exists between age, gender or weight. Lowest socioeconomic quintile has higher incidence of heart failure (p =0.018) but other past medical history was no different. No difference in incidence of alcohol misuse.

Prescription rate/rhythm control agents and anticoagulant use post ablation was not statistically different between all groups.

12 months follow-up demonstrated readmission for symptomatic documented AF was statistically higher among patients of lowest socioeconomic quintile (Keplan Meier plot, p = 0.001). Stepwise multiple regression analysis also confirmed multiple socioeconomic deprivation as an independent predictor for more adverse clinical outcome (p = 0.02).

Risk of readmission for AF in patients from the wealthiest socioeconomic group is almost a quarter as compared to those of most deprived social group (Odd-ratio 0.273 (95% CI 0.122 – 0.607)).

Other clinical outcomes including risk of admissions for heart failure, stroke, bleeding diathesis and all-cause mortality was not statistically different across all groups.

Summary

After cryoablation for AF, patients from the lower socioeconomic group are still more likely to experience readmission for symptomatic AF at 12-month, despite similar post-procedure pharmaceutical agents utilised.

Enteral myiasis causing acute dysentery: A case report

Enteral myiasis or intestinal myiasis is acquired by ingesting food or water contaminated with dipteran fly eggs or larvae. Here, we describe a patient with intestinal myiasis presenting with acute dysentery caused by the larva of Hermetia illucens. The larva was identified morphologically, and its species confirmed through molecular analysis using polymerase chain reaction and sequencing based on mitochondrial cytochrome c oxidase subunit I gene (COI).

Complications of Sub-microscopic Plasmodium vivax Malaria among Orang Asli in Pos Lenjang, Kuala Lipis

In recent years, increasing cases of Plasmodium vivax complications had been reported all over the world. This former benign Plasmodium species is now recognized to be one of the human malaria parasites that can produce severe disease. In this article, we report two cases of sub-microscopic P. vivax malaria confirmed by PCR. Both patients were asymptomatic before treatment. They showed unusual presentations few days after initiation of antimalarial treatment. Both patients had subsequently completed antimalarial treatment and recovered completely.

Elimination of contamination in loop-mediated isothermal amplification assay for detection of human malaria

The LAMP assay, amplifies the target DNA rapidly, with 10-fold greater sensitivity than conventional PCR. The greater sensitivity also comes with greater risks of contamination. To overcome this issue, the current project includes either uracil DNA glycosylase (UDG) or a mineral oil overlay in the LAMP assay. Our results indicated that UDG or a mineral oil overlay can effectively prevent carryover contamination in the LAMP assay for the detection of human malaria. By incorporating these preventative methods, contamination can be eliminated and LAMP can potentially be used in the field; and point of care diagnosis for human malaria.

Seropositivity and risk factors of Toxocara canis infection in adult asthmatic patients

This cross-sectional study involving 86 adult asthmatic patients aimed to determine the relationship between Toxocara seropositivity and severity of asthma in adult asthmatics and investigate the risk factors for Toxocara infection. In all cases, T. canis IgG level was measured using an anti-Toxocara IgG enzyme-linked immunosorbent assay kit. Total serum IgE and eosinophil count were also determined. The anti-Toxocara IgG seropositivity was 68.6% among asthmatic patients. There were no statistically significant associations between Toxocara seroprevalence and other risk factors, clinical symptoms of asthma and high level of total serum IgE and eosinophilia. Pet ownership could be an important risk factor for Toxocariasis. Having a pet at home and wheezing were significantly associated with Toxocara seropositivity in adult asthmatic patients.

Investigative study on the role of the Toxo 5699 gene in the Toxoplasma gondii lytic cycle using the CRISPR/Cas9 system

The focus of the current study was to disrupt the Toxo 5699 gene via CRISPR/Cas9 to evaluate the effects of gene disruption on the parasite lytic cycle. In the present work, a single plasmid expressing both the guide RNA and Cas9 nuclease together with a selectable marker of human dihydrofolate reductase (DHFR) was introduced into Toxoplasma gondii. Targeted disruption of the Toxo 5699 gene was carried out via the CRISPR/Cas9 system and confirmed by PCR, sequencing, and immunofluorescence microscopy. Disrupted and nondisrupted control parasites were allowed to invade HS27 cell monolayers and plaques were counted. The average number of plaques from three replicates per group was obtained between the disrupted and non-disrupted T. gondii RH strain and was compared using a onetailed t-test. It was observed that there was a significant decrease in number and size of plaque formation in the Toxo 5699 gene disrupted parasite line. This is an indication that the Toxo 5699 gene may play a role in the lytic cycle of the parasite, particularly during the replication phase and thus would be a novel target for disruption or silencing. The Toxo 5699 gene presented in the current work is an important part of the T. gondii lytic cycle, therefore meriting further inquiry into its potential as a target for further genetic-silencing or disruption studies.

P347Physician-led, weight loss advice prior to atrial fibrillation ablation, overall weight change and clinical outcomes

Background

Randomised trial, controlled study and international guidelines have advocated weight loss in AF patients with obesity as a means of attaining better AF burden control and maintenance of sinus rhythm. However, previous study required patients to undertake a highly structured weight management programme, detailed counselling, meal plans and behaviour modification.

Aim

To assess if weight-loss can be attained through a 5-minute, target-driven, physician-led counselling amongst overweight/obese patients referred AF ablation, without the need for intensive weight management programme. Subsequently to assess this can lead to better clinical outcomes (reduction in AF recurrence and readmission).

Methods

All patients referred for AF ablation in a tertiary centre over a 6-month period were included. Baseline weight and BMI at initial encounter plus  weight and BMI at day of AF ablation were recorded. Optional physician-led counselling was provided, with aim for target weight loss of <10% or reduction of 3 point in BMI.

Initial contact to AF ablation is 6 months.

Clinical outcomes such as symptomatic AF >3 months post AF ablation and readmission for symptomatic AF were recorded. Follow-up duration of 6 months post ablation.

Patients received counselling were designated Group 1, and those who did not were designated Group 2.

Outcomes

146 new AF referrals for ablation seen over the 6-month period. 105 (71.9%) are paroxysmal AF, 37 (25.3%) are persistent, 4 permanent AF.

Mean BMI 34.4 (+/- 5.1).  Out of which, 76% have BMI > 30 (Obese), 47.6% possess BMI >35 (Morbidly obese), with 1 patient with BMI exceeding 50.

21.9%  patients received physician-led counselling to lose weight. Basic demographics (age, gender), proportion of pAF and duration of AF, use of antiarrhythmic drugs were not statistically different between the two groups.

Among AF patients receiving weight-loss counselling (Group 1), they have higher mean weight and BMI, 108kg (+/- 14.3) and BMI 33.7 (+/-4.3), as compared to those who did not received counselling (Group 2), 87.5kg (+/- 16.2) and BMI 29.5 (+/-4.3).

At point of AF ablation, Group 1 has median weight loss of (-)4.5kg, mean reduction of BMI (-)2.0 points, while Group 2 has median weight gain of 3.6kg, increase of BMI 1.1 point. Overall statistically significant difference in weight change (p <0.001).

Composite clinical outcomes at 6 months post ablation comprising recurrence of AF and readmission for symptomatic AF were higher in Group 2 as compared to Group 1, 38% vs 13% (p = 0.03).

Summary

This small cohort study suggests that concise physician-led weight loss counselling (without dietician-led meal plan or extensive weight loss programme) provided to AF patients with increased BMI can lead to significant weight loss and lower BMI in the run-up to AF ablation. This is also associated with statistically significant reduction in recurrence of AF and hospital re-admission.

Skin prick testing a better predictor than blood testing for the diagnosis of peanut allergy in Chinese children

BACKGROUND

Peanut allergy is common in Chinese children, yet the most predictive diagnostic cut-offs for skin prick test (SPT) and blood testing in this population are unclear.

OBJECTIVES

We aimed to determine the optimal cut-off values for whole-peanut SPT, specific IgE (sIgE) and component-resolved diagnostics (CRD) for Chinese children based on outcomes of open oral food challenges (OFC) to peanut.

METHODS

We recruited ethnic-Chinese patients 1-18 years old who were suspected of having peanut allergy based on a history of reactions after exposure or sensitization although peanut naïve. Considering the AUC value of 0.8, 80% power and 5% level of significance with two tails, 26 patients were needed. Sensitivities, specificities, positive and negative predictive values, and receiver operating characteristic curves (ROCs) and their area-under-curves (AUCs) for SPT, peanut sIgE, and CRD were compared.

RESULTS

Thirty-one subjects participated. Only SPT reached statistical significance (AUC 0.91, p = 0.0001), but not the other tests. Seven retrospective data were added to optimize the power. SPT remained to be the best predictor, followed by Ara h 2 sIgE (AUC 0.72, p = 0.02). An SPT wheal size of 3 mm and Ara h 2 sIgE of 0.14 kU(A)/L yielded the highest Youden's index. The specificity of SPT and Ara h 2 sIgE reached 94% at 6 mm and 0.74 kU(A)/L, respectively. Comparisons of ROCs revealed that SPT was significantly better than Ara h 2 sIgE (p = 0.03) and whole-peanut sIgE (AUC 0.61, p = 0.26).

CONCLUSION

In Chinese children, SPT appeared to be the best predictor for peanut allergy, followed by Ara h 2 sIgE.

Investigation of possible rickettsial infection in patients with malaria

Rickettsioses are a common health problem in many geographical areas, including rural areas in Southeast Asia. Co-infection of rickettsioses and malaria has been reported in Africa, where common reservoir and vectors are available. In this study, blood samples of Malaysian patients microscopically positive (n=148) and negative (n=88) for malaria parasites (Plasmodium knowlesi, Plasmodium malariae, Plasmodium falciparum, and Plasmodium vivax) were screened for the presence of rickettsial DNA, using PCR assays targeting specific genes. A partial fragment of rickettsial ompB gene was successfully amplified and sequenced from a patient microscopically positive for Plasmodium spp. and PCR-positive for P. vivax. BLAST analysis of the ompB sequence demonstrated the highest sequence similarity (99.7% similarity, 408/409nt) with Rickettsia sp. RF2125 (Genbank accession no. JX183538) and 91.4% (374/409 nt) similarity with Rickettsia felis URRWXCal2 (Genbank accession no. CP000053). This study reports rickettsial infection in a malaria patient for the first time in the Southeast Asia region.

Detection of mutated Plasmodium vivax Kelch Propeller Domain (PvK12) in Malaysian isolates

Malaysia is located near the borders of countries where artemisinin resistant Plasmodium falciparum (mutations in the P. falciparum Kelch propeller domain [PfK13]) have been reported. Plasmodium vivax Kelch propeller domain, PvK12, the ortholog of PfK13, could assess resistance towards artemisinin in vivax malaria. Polymorphisms in PvK12 gene were determined by PCR and sequencing was done in 300 clinical isolates collected in recent years (2012-2017) from hospitals within the country. Among 48 P. vivax samples, all were Sal-1 wild type alleles except for two isolates, a synonymous and nonsynonymous mutation respectively. The nonsynonymous (V552I) isolate was collected from an immigrant. P. vivax with mutated PvK12 is speculated to be an imported case and is likely to be circulating at very low frequency in Malaysia. An in-depth drug resistance surveillance among immigrants needs to be investigated to provide information that may be crucial for drug policy changes.

Paediatric case series of drug reaction with eosinophilia and systemic symptoms (DRESS): 12-year experience at a single referral centre in Hong Kong and the first reported use of infliximab

Summary

DRESS (drug reaction with eosinophilia and systemic symptoms) is a rare but potentially life-threatening disorder characterized by fever, skin eruption, haematological abnormalities and multi-organ dysfunction after drug exposure. The pathophysiology is thought to be related to interactions between culprit drugs, viral reactivation and T-lymphocytes activation. We report 4 paediatric patients with DRESS who were treated at our centre over the past 12 years. Most cases improved after corticosteroids. Other immunosuppressive medications were attempted in refractory cases with varied outcomes. Patient 3 was the first reported case that involved the use of infliximab, a TNF-α inhibitor, for DRESS. Although clinical efficacy was not observed for this one patient, a previous study demonstrated that patients with DRESS, disease progression and HHV-6 reactivation had elevated pre-treatment TNF- α and IL-6 levels. Further research is needed to explore the role of these cytokines in DRESS.

Electronic-based lifestyle interventions in overweight or obese perinatal women: a systematic review and meta-analysis

Electronic-based (e-based) lifestyle interventions provide potential and cost-effective delivery of remote interventions for overweight and obese perinatal women. To date, no meta-analysis has reported the efficacy of maternal and neonatal outcomes. Seven electronic databases were searched from inception up to July 13, 2016, including the Cumulative Index to Nursing and Allied Health Literature, Cochrane Library, EMBASE, ProQuest Dissertations and Theses, PsycINFO, PubMed and Scopus. Among the 1,145 studies retrieved, 14 randomized controlled trials were selected among 17 publications. The Cochrane risk of bias tool was used to appraise the quality assessment. The meta-analyses demonstrated a significant result for limiting gestational weight gain, losing postnatal weight in 1-2 months, increasing self-reported moderate and vigorous physical activity and reducing caloric intake using diet-related software. Our review shows that an e-based lifestyle intervention is an acceptable approach. The findings reveal the variability in intervention methods and provide limited conclusive evidence. Thus, future studies should examine the efficacy and essential components as well as the various approaches using optimal portions of in-person and phone sessions. Further evaluations comparing the effectiveness of different e-based lifestyle intervention approaches toward activity-related and diet-related outcomes are necessary.

Development and validation of a new assay for assessing clot integrity

INTRODUCTION

Research and routine laboratory assessment of clot integrity can be time consuming, expensive, and cannot be batched as it is generally performed in real time. To address these issues, we developed and validated a micro-titre based assay to quantify thrombogenesis and fibrinolysis, the purpose being to assess patients at risk of cardiovascular events by virtue of hypercoagulability. In further validation, thrombogenesis results were compared to similar indices from the thrombelastograph (TEG).

METHODS

Our assay determines three indices of thrombogenesis (lag time to the start of thrombus formation (LT), rate of clot formation (RCF), and maximum clot density (MCD)) and two of fibrinolysis (rate of clot dissolution (RCD) and time for 50% of the clot to lyse (T50)). Plasma was tested fresh and again after being frozen at -70°C. Some samples were tested immediately, others after being left at room temperature for up to 24h.

RESULTS

The intra-assay coefficients of variation (CVs) of the three thrombogenesis measures (LT, RCF, MCD) and two fibrinolysis measures (RCD, T50) varied between 2.7 and 12.0% in fresh plasma and between 1.3% and 10.8% in frozen plasma respectively. Similarly, the inter-assay coefficients of variation of the thrombogenesis and fibrinolysis measures were 4.9-10.8% in fresh plasma and 2.2-6.5% in frozen plasma respectively. TEG assays intra- and inter assay CVs were around 25%. There were no significant differences in all plate assay indices up to 6h at room temperature. Certain plate assay thrombogenesis data were comparable to TEG indices after analysis by Pearson's correlation. The reagent processing cost per sample is £15 for TEG and £2 for the plate assays.

CONCLUSION

Our micro-titre based assay assessing plasma thrombogenesis and fibrinolysis has good intra- and inter-assay CVs, can assess plasma up to 6h after venepuncture, is more efficient (in terms of throughput) and is more economical than that of the TEG.

Compound heterozygous mutations in TTC7A cause familial multiple intestinal atresias and severe combined immunodeficiency

Familial multiple intestinal atresias is an autosomal recessive disease with or without combined immunodeficiency. In the last year, several reports have described mutations in the gene TTC7A as causal to the disease in different populations. However, exact correlation between different genotypes and various phenotypes are not clear. In this study, we report identification of novel compound heterozygous mutations in TTC7A gene in a Malay girl with familial multiple intestinal atresias and severe combined immunodeficiency (MIA-SCID) by whole exome sequencing. We found two mutations in TTC7A: one that destroyed a putative splicing acceptor at the junction of intron 17/exon 18 and one that introduced a stop codon that would truncate the last two amino acids of the encoded protein. Reviewing the recent reports on TTC7A mutations reveals correlation between the position and nature of the mutations with patient survival and clinical manifestations. Examination of public databases also suggests carrier status for healthy individuals, making a case for population screening on this gene, especially in populations with suspected frequent founder mutations.

Allergy in Hong Kong: an unmet need in service provision and training

Many children in Hong Kong have allergic diseases and epidemiological data support a rising trend. Only a minority of children will grow out of their allergic diseases, so the heavy clinical burden will persist into adulthood. In an otherwise high-quality health care landscape in Hong Kong, allergy services and training are a seriously unmet need. There is one allergy specialist for 1.5 million people, which is low not only compared with international figures, but also compared with most other specialties in Hong Kong. The ratio of paediatric and adult allergists per person is around 1:460 000 and 1:2.8 million, respectively, so there is a severe lack of adult allergists, while the paediatric allergists only spend a fraction of their time working with allergy. There are no allergists and no dedicated allergy services in adult medicine in public hospitals. Laboratory support for allergy and immunology is not comprehensive and there is only one laboratory in the public sector supervised by accredited immunologists. These findings clearly have profound implications for the profession and the community of Hong Kong and should be remedied without delay. Key recommendations are proposed that could help bridge the gaps, including the creation of two new pilot allergy centres in a hub-and-spoke model in the public sector. This could require recruitment of specialists from overseas to develop the process if there are no accredited allergy specialists in Hong Kong who could fulfil this role.

Molecular detection of Entamoeba histolytica and Entamoeba dispar infection among wild rats in Kuala Lumpur, Malaysia

Entamoeba histolytica infection is the third-greatest parasitic disease responsible for death in the world. Wild rats harbouring E. histolytica can be the possible reservoir hosts for human amoebiasis. There were numerous studies on prevalence of intestinal parasites among wild rats in Malaysia but none has reported E. histolytica. Rats were captured from Sentul and Chow Kit areas, Kuala Lumpur, Malaysia. The preserved stool samples were used for microscopy examination and molecular analysis. Out of 137 samples collected, 12 were positive for E. histolytica / E. dispar / E. moshkovskii microscopically. Two E. histolytica (1.4%), 1 E. dispar (0.7%) and 6 mixed infections of E. histolytica and E. dispar (4.3%) were detected using PCR. This is the first report of molecular detection of E. histolytica/dispar infection among wild rats in Malaysia. This study provides useful information about the potential risks of zoonotic agents and the importance of developing control measures to prevent zoonotic transmission.

Evaluation of codon optimized recombinant Plasmodium knowlesi merozoite surface protein-119 (pkMSP-119) expressed in Pichia pastoris

Malaria causes high global mortality and morbidity annually. Plasmodium knowlesi has been recognised as the fifth human Plasmodium sp. and its infection is widely distributed in Southeast Asia. Merozoite surface protein-119 (MSP-119) appears as a potential candidate for malaria blood stage vaccine as it could induce protective immunity. In this study, codon optimized P. knowlesi MSP-119 (pkMSP-119) was expressed and purified in yeast Pichia pastoris expression system. The purified recombinant protein was further evaluated using Western blot assay using knowlesi malaria, non-knowlesi human malaria, non-malarial parasitic infections and healthy serum samples (n = 50). The sensitivity of purified pkMSP-119 towards detection of knowlesi infection was as 28.6% (2/7). pkMSP-119 did not react with all non-malarial parasitic infections and healthy donor sera, yet reacted with some non-knowlesi human malaria sera, therefore lead to a specificity of 86.0% (37/43).

A real-time loop-mediated isothermal amplification assay for rapid detection of Shigella species

Shigellosis is a foodborne illness caused by the genus Shigella and is an important global health issue. The development of effective techniques for rapid detection of this pathogen is essential for breaking the chain of transmission. Therefore, we have developed a novel loop-mediated isothermal amplification (LAMP) assay targeting the invasion plasmid antigen H (ipaH) gene to rapidly detect Shigella species. This assay could be performed in 90 min at an optimal temperature of 64ºC, with endpoint results visualized directly. Notably, the method was found to be more sensitive than conventional PCR. Indeed, the detection limit for the LAMP assay on pure bacterial cultures was 5.9 x 10(5) CFU/ml, while PCR displayed a limit of 5.9 x 10(7) CFU/ml. In spiked lettuce samples, the sensitivity of the LAMP assay was 3.6 x 10(4) CFU/g, whereas PCR was 3.6 x 10(5) CFU/g. Overall, the assay accurately identified 32 Shigella spp. with one enteroinvasive Escherichia coli displaying positive reaction while the remaining 32 non-Shigella strains tested were negative.

Sequence analysis of the PIP5K locus in Eimeria maxima provides further evidence for eimerian genome plasticity and segmental organization

Commercial flocks infected by Eimeria species parasites, including Eimeria maxima, have an increased risk of developing clinical or subclinical coccidiosis; an intestinal enteritis associated with increased mortality rates in poultry. Currently, infection control is largely based on chemotherapy or live vaccines; however, drug resistance is common and vaccines are relatively expensive. The development of new cost-effective intervention measures will benefit from unraveling the complex genetic mechanisms that underlie host-parasite interactions, including the identification and characterization of genes encoding proteins such as phosphatidylinositol 4-phosphate 5-kinase (PIP5K). We previously identified a PIP5K coding sequence within the E. maxima genome. In this study, we analyzed two bacterial artificial chromosome clones presenting a ~145-kb E. maxima (Weybridge strain) genomic region spanning the PIP5K gene locus. Sequence analysis revealed that ~95% of the simple sequence repeats detected were located within regions comparable to the previously described feature-rich segments of the Eimeria tenella genome. Comparative sequence analysis with the orthologous E. maxima (Houghton strain) region revealed a moderate level of conserved synteny. Unique segmental organizations and telomere-like repeats were also observed in both genomes. A number of incomplete transposable elements were detected and further scrutiny of these elements in both orthologous segments revealed interesting nesting events, which may play a role in facilitating genome plasticity in E. maxima. The current analysis provides more detailed information about the genome organization of E. maxima and may help to reveal genotypic differences that are important for expression of traits related to pathogenicity and virulence.

Comparison of two nested PCR methods for the detection of human malaria

Battling malaria will be a persistent struggle without the proper means to diagnose the parasitic infection. However, the inherent limitations of microscopy, the conventional method of diagnosing malaria, affect the accuracy of diagnosis. The present study aimed to compare the accuracy of two different set of primers targeting the small subunit ribosomal RNA (ssRNA) and the dihydrofolate reductase-thymidylate synthase linker region (dhfr-ts) in detecting species specific malaria infections by nested PCR. The sensitivity and specificity of nested PCR assay using the two primers were calculated with reference to microscopy as the 'gold standard'. The results show that 18S rRNA primers had 91.9% sensitivity and 100% specificity in detecting human Plasmodium species as opposed to dhfr-ts primers which had 51.4% sensitivity and 100% specificity. The higher sensitivity of 18S rRNA primers suggests that it may be a better diagnostic tool for detecting human malaria.

Chronic health problems and health-related quality of life in Chinese children and adolescents: a population-based study in Hong Kong

OBJECTIVE

We examined the association of different chronic physical and mental conditions, individually or comorbidly on health-related quality of life (QoL) in Chinese children aged ≤14 years in Hong Kong.

DESIGN

Population-based cross-sectional survey.

PARTICIPANTS

Approximately 7500 Chinese children aged <14 years in Hong Kong.

INTERVENTIONS

Nil.

PRIMARY AND SECONDARY OUTCOME MEASURES

Various health concepts of validated Chinese version of Child Health Questionnaire (CHQ), a health-related QoL questionnaire in children.

RESULT

There was significant association of physical and mental health conditions, either individually or comorbidly, on the various concepts of CHQ. Children with mental health problems were apparently more affected than those with physical health problems. Chronic renal disease and congenital malformation were the physical health conditions associated with the lowest scores in CHQ concepts in children aged 5-10 years and aged 10-14 years, respectively. Behavioural problem was the mental health condition associated with the lowest score in CHQ concepts in both age groups.

CONCLUSIONS

Our study shows important information concerning the prevalence of different health conditions and its association, either individually or comorbidly on the QoL in a representative sample of Chinese children in HK.

Reliability of acute illness dihydrorhodamine-123 testing for chronic granulomatous disease

BACKGROUND

Dihydrorhodamine (DHR) flow cytometric analysis is used to evaluate granulocyte oxidative bursts and is the test of choice for the diagnosis of chronic granulomatous disease (CGD). We present the clinical and DHR test profiles of five subjects assessed during and after acute illness.

METHODS

This was a retrospective report of the findings of five out of a total of one hundred and seventeen patients, whose blood was sent to the laboratory for dihydrorhodamine-123 flow cytometry testing between January 2005 and December 2010. Using whole blood technique and stimulation using phorbol myristate acetate, the results of DHR were expressed as stimulation index and coefficient of variation of histograms of stimulated cells and compared with healthy controls. DHR tests were repeated when the patients had recovered and were clinically well.

RESULTS

These five patients showed abnormal DHR test results during their acute illness, with a stimulation index (SI) lower (p = 0.009) and coefficient of variation (CV) higher (p = 0.009) than controls. The DHR profiles repeated when patients had recovered showed normalization of tests with no significant difference for SI (p = 0.602) and CV (p = 0.917) compared to controls. Wilcoxon Signed Rank tests showed a significant improvement in SI (p = 0.043) and CV (p = 0.043) upon recovery. On follow up, all five patients were well, with no further severe or atypical infections.

CONCLUSIONS

DHR may be transiently abnormal during acute illness, and may therefore not be reliable when assessed during an acute illness. If these subjects had CGD, it would be of a hypomorphic variant that has not previously been described.

Foetal exposure to maternal passive smoking is associated with childhood asthma, allergic rhinitis, and eczema

Objective. We examined the hypothesis that foetal exposure to maternal passive smoking is associated with childhood asthma, allergic rhinitis, and eczema. Methods. The study was a population-based cross-sectional survey of Hong Kong Chinese children aged ≤14 years carried out in 2005 to 2006. Results. Foetal exposure to maternal passive smoking was significantly associated with wheeze ever (OR 2.05; 95% CI 1.58–2.67), current wheeze (OR 2.06; 95% CI 1.48–2.86), allergic rhinitis ever (OR 1.22; 95% CI 1.09–1.37), and eczema ever (OR 1.61; 95% CI 1.38–1.87). Foetal exposure to maternal active smoking was significantly associated with asthma ever (OR 2.10; 95% CI 1.14–3.84), wheeze ever (OR 2.46; 95% CI 1.27–4.78), and current wheeze (OR 2.74; 95% CI 1.24–6.01) but not with allergic rhinitis ever (OR 1.01; 95% CI 0.70–1.46) or eczema ever (OR 1.38; 95% CI 0.87–2.18). The dose response relationship between wheeze ever and current wheeze with increasing exposure, from no exposure to maternal passive smoking and then to maternal active smoking, further supports causality. Conclusion. There is significant association between foetal exposure to maternal passive smoking and maternal active smoking with childhood asthma and related atopic illnesses. Further studies are warranted to explore the potential causal relationship.

Autonomic dysfunction in ischemic stroke with carotid stenosis

OBJECTIVES

Impaired autonomic function is common in acute ischemic stroke. Previous limited studies have suggested that atherosclerosis may affect the distensibility of the carotid sinus and then impair the cardiovascular autonomic function. This study sought to investigate cardiovascular autonomic function in patients with ischemic stroke with carotid stenosis.

METHODS

Eighty-five patients with ischemic stroke (58 ones without carotid stenosis and 27 ones with carotid stenosis, average 6 months after stroke onset) and 37 elderly controls were recruited. All performed Ewing's battery autonomic function tests.

RESULTS

From Ewing's battery of autonomic function tests, atypical, definite, or severe autonomic dysfunction was identified in 69.0% patients without carotid stenosis and 88.9% with carotid stenosis, with significant difference between the two groups, and the prevalence of autonomic dysfunction in both groups was higher than that in controls (21.6%). Patients with carotid stenosis showed impairment of all parasympathetic tests (all P < 0.05) and one of the sympathetic tests [Mean fall in systolic blood pressure (BP) on standing: P = 0.051], and those without carotid stenosis only showed impairment in two parasympathetic tests (Valsalva ratio: P = 0.014; heart rate response to deep breathing: P < 0.001) in comparison with controls. Patients with carotid stenosis had significantly more impairment than those without carotid stenosis in some autonomic parameters (Valsalva ratio: P < 0.05; mean fall in systolic BP on standing: P < 0.05).

CONCLUSIONS

Cardiovascular autonomic function is impaired in patients with ischemic stroke, but patients with carotid stenosis show more severely impaired parasympathetic and sympathetic functions.

Optimization of the expression of surface antigen SAG1/2 of Toxoplasma gondii in the yeast Pichia pastoris

Surface antigens are the most abundant proteins found on the surface of the parasite Toxoplasma gondii. Surface antigen 1 (SAG1) and Surface antigen 2 (SAG2) remain the most important and extensively studied surface proteins. These antigens have been identified to play a role in host cell invasion, immune modulation, virulence attenuation. Recombinant SAG1/2 was cloned and expressed in yeast Pichia pastoris. We describe here optimization of critical parameters involved in high yield expression of the recombinant SAG1/2. Our results suggest that recombinant SAG1/2 were best expressed at 30ºC, pH 6 and 1% methanol as the carbon source by X33 Pichia cells. Additional optimizations included the downstream process such as ammonium sulphate precipitation and dialysis. The fusion protein was purified using Ni-NTA purification system with 80% recovery. The purified protein was 100% specific and sensitive in detection of toxoplasmosis.

A novel CYBB mutation with the first genetically confirmed case of chronic granulomatous disease in South Africa

A case of a child with chronic granulomatous disease (CGD) presenting with recurrent mycobacterial infections and invasive Aspergillus fumigatus disease is described. Genetic analysis confirmed X-linked CGD with a novel mutation in exon 10 of the CYBB gene - the first South African report of genetically confirmed CGD.