Spatio-temporal spread of artemisinin resistance in Southeast Asia

Current malaria elimination targets must withstand a colossal challenge-resistance to the current gold standard antimalarial drug, namely artemisinin derivatives. If artemisinin resistance significantly expands to Africa or India, cases and malaria-related deaths are set to increase substantially. Spatial information on the changing levels of artemisinin resistance in Southeast Asia is therefore critical for health organisations to prioritise malaria control measures, but available data on artemisinin resistance are sparse. We use a comprehensive database from the WorldWide Antimalarial Resistance Network on the prevalence of non-synonymous mutations in the Kelch 13 (K13) gene, which are known to be associated with artemisinin resistance, and a Bayesian geostatistical model to produce spatio-temporal predictions of artemisinin resistance. Our maps of estimated prevalence show an expansion of the K13 mutation across the Greater Mekong Subregion from 2000 to 2022. Moreover, the period between 2010 and 2015 demonstrated the most spatial change across the region. Our model and maps provide important insights into the spatial and temporal trends of artemisinin resistance in a way that is not possible using data alone, thereby enabling improved spatial decision support systems on an unprecedented fine-scale spatial resolution. By predicting for the first time spatio-temporal patterns and extents of artemisinin resistance at the subcontinent level, this study provides critical information for supporting malaria elimination goals in Southeast Asia.

A proposed method of grading malaria chemoprevention efficacy

The efficacy and effectiveness of antimalarial drugs are threatened by increasing levels of resistance and therefore require continuous monitoring. Chemoprevention is increasingly deployed as a malaria control measure, but there are no generally accepted methods of assessment. We propose a simple method of grading the parasitological response to chemoprevention (focusing on seasonal malaria chemoprevention) that is based on pharmacometric assessment.

Development of weight and age-based dosing of daily primaquine for radical cure of vivax malaria

BACKGROUND

In many endemic areas, Plasmodium vivax malaria is predominantly a disease of young adults and children. International recommendations for radical cure recommend fixed target doses of 0.25 or 0.5 mg/kg/day of primaquine for 14 days in glucose-6-phosphate dehydrogenase normal patients of all ages. However, for many anti-malarial drugs, including primaquine, there is evidence that children have lower exposures than adults for the same weight-adjusted dose. The aim of the study was to develop 14-day weight-based and age-based primaquine regimens against high-frequency relapsing tropical P. vivax.

METHODS

The recommended adult target dose of 0.5 mg/kg/day (30 mg in a 60 kg patient) is highly efficacious against tropical P. vivax and was assumed to produce optimal drug exposure. Primaquine doses were calculated using allometric scaling to derive a weight-based primaquine regimen over a weight range from 5 to 100 kg. Growth curves were constructed from an anthropometric database of 53,467 individuals from the Greater Mekong Subregion (GMS) to define weight-for-age relationships. The median age associated with each weight was used to derive an age-based dosing regimen from the weight-based regimen.

RESULTS

The proposed weight-based regimen has 5 dosing bands: (i) 5-7 kg, 5 mg, resulting in 0.71-1.0 mg/kg/day; (ii) 8-16 kg, 7.5 mg, 0.47-0.94 mg/kg/day; (iii) 17-40 kg, 15 mg, 0.38-0.88 mg/kg/day; (iv) 41-80 kg, 30 mg, 0.37-0.73 mg/kg/day; and (v) 81-100 kg, 45 mg, 0.45-0.56 mg/kg/day. The corresponding age-based regimen had 4 dosing bands: 6-11 months, 5 mg, 0.43-1.0 mg/kg/day; (ii) 1-5 years, 7.5 mg, 0.35-1.25 mg/kg/day; (iii) 6-14 years, 15 mg, 0.30-1.36 mg/kg/day; and (iv) ≥ 15 years, 30 mg, 0.35-1.07 mg/kg/day.

CONCLUSION

The proposed weight-based regimen showed less variability around the primaquine dose within each dosing band compared to the age-based regimen and is preferred. Increased dose accuracy could be achieved by additional dosing bands for both regimens. The age-based regimen might not be applicable to regions outside the GMS, which must be based on local anthropometric data. Pharmacokinetic data in small children are needed urgently to inform the proposed regimens.

Impact of delays to incubation and storage temperature on blood culture results: a multi-centre study

Background

Blood cultures are one of the most important tests performed by microbiology laboratories. Many hospitals, particularly in low and middle-income countries, lack either microbiology services or staff to provide 24 h services resulting in delays to blood culture incubation. There is insufficient guidance on how to transport/store blood cultures if delays before incubation are unavoidable, particularly if ambient temperatures are high. This study set out to address this knowledge gap.

Methods

In three South East Asian countries, four different blood culture systems (two manual and two automated) were used to test blood cultures spiked with five common bacterial pathogens. Prior to incubation the spiked blood culture bottles were stored at different temperatures (25 °C, in a cool-box at ambient temperature, or at 40 °C) for different lengths of time (0 h, 6 h, 12 h or 24 h). The impacts of these different storage conditions on positive blood culture yield and on time to positivity were examined.

Results

There was no significant loss in yield when blood cultures were stored < 24 h at 25 °C, however, storage for 24 h at 40 °C decreased yields and longer storage times increased times to detection.

Conclusion

Blood cultures should be incubated with minimal delay to maximize pathogen recovery and timely result reporting, however, this study provides some reassurance that unavoidable delays can be managed to minimize negative impacts. If delays to incubation ≥ 12 h are unavoidable, transportation at a temperature not exceeding 25 °C, and blind sub-cultures prior to incubation should be considered.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-05872-8.

Molecular epidemiology of resistance to antimalarial drugs in the Greater Mekong subregion: an observational study

BACKGROUND

The Greater Mekong subregion is a recurrent source of antimalarial drug resistance in Plasmodium falciparum malaria. This study aimed to characterise the extent and spread of resistance across this entire region between 2007 and 2018.

METHODS

P falciparum isolates from Myanmar, Thailand, Laos, and Cambodia were obtained from clinical trials and epidemiological studies done between Jan 1, 2007, and Dec 31, 2018, and were genotyped for molecular markers (pfkelch, pfcrt, pfplasmepsin2, and pfmdr1) of antimalarial drug resistance. Genetic relatedness was assessed using microsatellite and single nucleotide polymorphism typing of flanking sequences around target genes.

FINDINGS

10 632 isolates were genotyped. A single long pfkelch Cys580Tyr haplotype (from -50 kb to +31·5 kb) conferring artemisinin resistance (PfPailin) now dominates across the eastern Greater Mekong subregion. Piperaquine resistance associated with pfplasmepsin2 gene amplification and mutations in pfcrt downstream of the Lys76Thr chloroquine resistance locus has also developed. On the Thailand-Myanmar border a different pfkelch Cys580Tyr lineage rose to high frequencies before it was eliminated. Elsewhere in Myanmar the Cys580Tyr allele remains widespread at low allele frequencies. Meanwhile a single artemisinin-resistant pfkelch Phe446Ile haplotype has spread across Myanmar. Despite intense use of dihydroartemisinin-piperaquine in Kayin state, eastern Myanmar, both in treatment and mass drug administrations, no selection of piperaquine resistance markers was observed. pfmdr1 amplification, a marker of resistance to mefloquine, remains at low prevalence across the entire region.

INTERPRETATION

Artemisinin resistance in P falciparum is now prevalent across the Greater Mekong subregion. In the eastern Greater Mekong subregion a multidrug resistant P falciparum lineage (PfPailin) dominates. In Myanmar a long pfkelch Phe446Ile haplotype has spread widely but, by contrast with the eastern Greater Mekong subregion, there is no indication of artemisinin combination therapy (ACT) partner drug resistance from genotyping known markers, and no evidence of spread of ACT resistant P falciparum from the east to the west. There is still a window of opportunity to prevent global spread of ACT resistance.

FUNDING

Thailand Science Research and Innovation, Initiative 5%, Expertise France, Wellcome Trust.

Mass drug administrations with dihydroartemisinin-piperaquine and single low dose primaquine to eliminate Plasmodium falciparum have only a transient impact on Plasmodium vivax: Findings from randomised controlled trials

Background

Mass administrations of antimalarial drugs (MDA) have reduced the incidence and prevalence of P. falciparum infections in a trial in the Greater Mekong Subregion. Here we assess the impact of the MDA on P. vivax infections.

Methods

Between May 2013 and July 2017, four villages in each Myanmar, Vietnam, Cambodia and Lao PDR were selected based on high prevalence of P. falciparum infections. Eight of the 16 villages were randomly assigned to receive MDA consisting of three-monthly rounds of three-day courses of dihydroartemisinin-piperaquine and, except in Cambodia, a single low-dose of primaquine. Cross-sectional surveys were conducted at quarterly intervals to detect Plasmodium infections using ultrasensitive qPCR. The difference in the cumulative incidence between the groups was assessed through a discrete time survival approach, the difference in prevalence through a difference-in-difference analysis, and the difference in the number of participants with a recurrence of P. vivax infection through a mixed-effect logistic regression.

Results

3,790 (86%) residents in the intervention villages participated in at least one MDA round, of whom 2,520 (57%) participated in three rounds. The prevalence of P. vivax infections fell from 9.31% to 0.89% at month 3 but rebounded by six months to 5.81%. There was no evidence that the intervention reduced the cumulative incidence of P.vivax infections (95% confidence interval [CI] Odds ratio (OR): 0.29 to 1.36). Similarly, there was no evidence of MDA related reduction in the number of participants with at least one recurrent infection (OR: 0.34; 95% CI: 0.08 to 1.42).

Conclusion

MDA with schizontocidal drugs had a lasting effect on P. falciparum infections but only a transient effect on the prevalence of P. vivax infections. Radical cure with an 8-aminoquinoline will be needed for the rapid elimination of vivax malaria.

The probability of a sequential Plasmodium vivax infection following asymptomatic Plasmodium falciparum and P. vivax infections in Myanmar, Vietnam, Cambodia, and Laos

BACKGROUND

Adding 8-aminoquinoline to the treatment of falciparum, in addition to vivax malaria, in locations where infections with both species are prevalent could prevent vivax reactivation. The potential risk of haemolysis under a universal radical cure policy using 8-aminoquinoline needs to be weighed against the benefit of preventing repeated vivax episodes. Estimating the frequency of sequential Plasmodium vivax infections following either falciparum or vivax malaria episodes is needed for such an assessment.

METHODS

Quarterly surveillance data collected during a mass drug administration trial in the Greater Mekong Subregion in 2013-17 was used to estimate the probability of asymptomatic sequential infections by the same and different Plasmodium species. Asymptomatic Plasmodium infections were detected by high-volume ultrasensitive qPCR. Quarterly surveys of asymptomatic Plasmodium prevalence were used to estimate the probability of a P. vivax infection following Plasmodium falciparum and P. vivax infections.

RESULTS

16,959 valid sequential paired test results were available for analysis. Of these, 534 (3%) had an initial P. falciparum monoinfection, 1169 (7%) a P. vivax monoinfection, 217 (1%) had mixed (P. falciparum + P. vivax) infections, and 15,039 (89%) had no Plasmodium detected in the initial survey. Participants who had no evidence of a Plasmodium infection had a 4% probability to be found infected with P. vivax during the subsequent survey. Following an asymptomatic P. falciparum monoinfection participants had a 9% probability of having a subsequent P. vivax infection (RR 2.4; 95% CI 1.8 to 3.2). Following an asymptomatic P. vivax monoinfection, the participants had a 45% probability of having a subsequent P. vivax infection. The radical cure of 12 asymptomatic P. falciparum monoinfections would have prevented one subsequent P. vivax infection, whereas treatment of 2 P. vivax monoinfections may suffice to prevent one P. vivax relapse.

CONCLUSION

Universal radical cure could play a role in the elimination of vivax malaria. The decision whether to implement universal radical cure for P. falciparum as well as for P. vivax depends on the prevalence of P. falciparum and P. vivax infections, the prevalence and severity of G6PD deficiency in the population and the feasibility to administer 8-aminoquinoline regimens safely. Trial registration ClinicalTrials.gov Identifier: NCT01872702, first posted June 7th 2013, https://clinicaltrials.gov/ct2/show/NCT01872702. This study was registered with ClinicalTrials.gov under NCT02802813 on 16th June 2016. https://clinicaltrials.gov/ct2/show/NCT02802813.

Intracluster correlation coefficients in the Greater Mekong Subregion for sample size calculations of cluster randomized malaria trials

BACKGROUND

Sample size calculations for cluster randomized trials are a recognized methodological challenge for malaria research in pre-elimination settings. Positively correlated responses from the participants in the same cluster are a key feature in the estimated sample size required for a cluster randomized trial. The degree of correlation is measured by the intracluster correlation coefficient (ICC) where a higher coefficient suggests a closer correlation hence less heterogeneity within clusters but more heterogeneity between clusters.

METHODS

Data on uPCR-detected Plasmodium falciparum and Plasmodium vivax infections from a recent cluster randomized trial which aimed at interrupting malaria transmission through mass drug administrations were used to calculate the ICCs for prevalence and incidence of Plasmodium infections. The trial was conducted in four countries in the Greater Mekong Subregion, Laos, Myanmar, Vietnam and Cambodia. Exact and simulation approaches were used to estimate ICC values for both the prevalence and the incidence of parasitaemia. In addition, the latent variable approach to estimate ICCs for the prevalence was utilized.

RESULTS

The ICCs for prevalence ranged between 0.001 and 0.082 for all countries. The ICC from the combined 16 villages in the Greater Mekong Subregion were 0.26 and 0.21 for P. falciparum and P. vivax respectively. The ICCs for incidence of parasitaemia ranged between 0.002 and 0.075 for Myanmar, Cambodia and Vietnam. There were very high ICCs for incidence in the range of 0.701 to 0.806 in Laos during follow-up.

CONCLUSION

ICC estimates can help researchers when designing malaria cluster randomized trials. A high variability in ICCs and hence sample size requirements between study sites was observed. Realistic sample size estimates for cluster randomized malaria trials in the Greater Mekong Subregion have to assume high between cluster heterogeneity and ICCs. This work focused on uPCR-detected infections; there remains a need to develop more ICC references for trials designed around prevalence and incidence of clinical outcomes. Adequately powered trials are critical to estimate the benefit of interventions to malaria in a reliable and reproducible fashion.

TRIAL REGISTRATION

ClinicalTrials.govNCT01872702. Registered 7 June 2013. Retrospectively registered. https://clinicaltrials.gov/ct2/show/NCT01872702.

Community engagement, social context and coverage of mass anti-malarial administration: Comparative findings from multi-site research in the Greater Mekong sub-Region

BACKGROUND

Between 2013 and 2017, targeted malaria elimination (TME), a package of interventions that includes mass drug administration (MDA)-was piloted in communities with reservoirs of asymptomatic P. falciparum across the Greater Mekong sub-Region (GMS). Coverage in target communities is a key determinant of the effectiveness of MDA. Drawing on mixed methods research conducted alongside TME pilot studies, this article examines the impact of the community engagement, local social context and study design on MDA coverage.

METHODS AND FINDINGS

Qualitative and quantitative data were collected using questionnaire-based surveys, semi-structured and in-depth interviews, focus group discussions, informal conversations, and observations of study activities. Over 1500 respondents were interviewed in Myanmar, Vietnam, Cambodia and Laos. Interview topics included attitudes to malaria and experiences of MDA. Overall coverage of mass anti-malarial administration was high, particularly participation in at least a single round (85%). Familiarity with and concern about malaria prompted participation in MDA; as did awareness of MDA and familiarity with the aim of eliminating malaria. Fear of adverse events and blood draws discouraged people. Hence, community engagement activities sought to address these concerns but their impact was mediated by the trust relationships that study staff could engender in communities. In contexts of weak healthcare infrastructure and (cash) poverty, communities valued the study's ancillary care and the financial compensation. However, coverage did not necessarily decrease in the absence of cash compensation. Community dynamics, affected by politics, village conformity, and household decision-making also affected coverage.

CONCLUSIONS

The experimental nature of TME presented particular challenges to achieving high coverage. Nonetheless, the findings reflect those from studies of MDA under implementation conditions and offer useful guidance for potential regional roll-out of MDA: it is key to understand target communities and provide appropriate information in tailored ways, using community engagement that engenders trust.

The impact of targeted malaria elimination with mass drug administrations on falciparum malaria in Southeast Asia: A cluster randomised trial

BACKGROUND

The emergence and spread of multidrug-resistant Plasmodium falciparum in the Greater Mekong Subregion (GMS) threatens global malaria elimination efforts. Mass drug administration (MDA), the presumptive antimalarial treatment of an entire population to clear the subclinical parasite reservoir, is a strategy to accelerate malaria elimination. We report a cluster randomised trial to assess the effectiveness of dihydroartemisinin-piperaquine (DP) MDA in reducing falciparum malaria incidence and prevalence in 16 remote village populations in Myanmar, Vietnam, Cambodia, and the Lao People's Democratic Republic, where artemisinin resistance is prevalent.

METHODS AND FINDINGS

After establishing vector control and community-based case management and following intensive community engagement, we used restricted randomisation within village pairs to select 8 villages to receive early DP MDA and 8 villages as controls for 12 months, after which the control villages received deferred DP MDA. The MDA comprised 3 monthly rounds of 3 daily doses of DP and, except in Cambodia, a single low dose of primaquine. We conducted exhaustive cross-sectional surveys of the entire population of each village at quarterly intervals using ultrasensitive quantitative PCR to detect Plasmodium infections. The study was conducted between May 2013 and July 2017. The investigators randomised 16 villages that had a total of 8,445 residents at the start of the study. Of these 8,445 residents, 4,135 (49%) residents living in 8 villages, plus an additional 288 newcomers to the villages, were randomised to receive early MDA; 3,790 out of the 4,423 (86%) participated in at least 1 MDA round, and 2,520 out of the 4,423 (57%) participated in all 3 rounds. The primary outcome, P. falciparum prevalence by month 3 (M3), fell by 92% (from 5.1% [171/3,340] to 0.4% [12/2,828]) in early MDA villages and by 29% (from 7.2% [246/3,405] to 5.1% [155/3,057]) in control villages. Over the following 9 months, the P. falciparum prevalence increased to 3.3% (96/2,881) in early MDA villages and to 6.1% (128/2,101) in control villages (adjusted incidence rate ratio 0.41 [95% CI 0.20 to 0.84]; p = 0.015). Individual protection was proportional to the number of completed MDA rounds. Of 221 participants with subclinical P. falciparum infections who participated in MDA and could be followed up, 207 (94%) cleared their infections, including 9 of 10 with artemisinin- and piperaquine-resistant infections. The DP MDAs were well tolerated; 6 severe adverse events were detected during the follow-up period, but none was attributable to the intervention.

CONCLUSIONS

Added to community-based basic malaria control measures, 3 monthly rounds of DP MDA reduced the incidence and prevalence of falciparum malaria over a 1-year period in areas affected by artemisinin resistance. P. falciparum infections returned during the follow-up period as the remaining infections spread and malaria was reintroduced from surrounding areas. Limitations of this study include a relatively small sample of villages, heterogeneity between villages, and mobility of villagers that may have limited the impact of the intervention. These results suggest that, if used as part of a comprehensive, well-organised, and well-resourced elimination programme, DP MDA can be a useful additional tool to accelerate malaria elimination.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01872702.

Migration histories of multidrug-resistant tuberculosis patients from the Thailand-Myanmar border, 2012-2014

SETTING

Multidrug-resistant tuberculosis (MDR-TB) is a growing public health threat in South-East Asia. TB is typically a disease of poverty and can be spread by infectious humans who migrate from one region to another.

DESIGN

We interviewed 20 MDR-TB patients on the Thailand-Myanmar border with regard to their migration histories. Migration origins and destinations were mapped.

RESULTS

All but one participant had a history of migration, and maps of migration ranges revealed wide geographic dispersal. Most described living and work conditions that could contribute to the spread of drug-resistant TB, including numerous contacts and crowded living quarters.

CONCLUSION

Our results show that at least some migrant workers in the region carry MDR-TB, and indicate that this subgroup of the population is important with regard to the transmission of MDR-TB throughout the region. Migrants in this region come into contact with high numbers of people and may be able to spread the disease across wide geographic ranges. Access to diagnosis and treatment and socio-economic development are at least as important as any TB control measures, meaning that innovative and bold approaches that extend across international borders are needed to address these problems.

Challenges in tackling tuberculosis on the Thai-Myanmar border: findings from a qualitative study with health professionals

Background

Myanmar and Thailand belong to the top 22 high burden countries for tuberculosis (TB). Health care organizations play an essential role in addressing TB control in the two bridging border jurisdictions, Tak province, Thailand and Myawaddy district, Kayin state, Myanmar. However, health professionals face difficulties in TB control effort due to the nature of fluid population movements, resource constraints and ambiguous mechanisms to implement collaboration along the border. The purpose of this study is to identify the challenges to TB control among Myanmar migrants faced by stakeholders, focusing on the area of collaboration and interaction along the border.

Method

The study conducted in-depth interviews with health policy makers and health care providers responsible for developing and implementing policies and TB programs in Tak province, Thailand and Myawaddy district, Kayin state, Myanmar. The participants included members of government organizations, United Nations agencies, community based organizations, and international NGO. One or two key stakeholders from each organization were approached to participate in the study. We gathered baseline information to identify TB policies and programs available on websites, brochures, and publications. Observations including field notes were made on site. The data transcriptions were coded for qualitative data analysis. Coding also developed categories that led to key themes.

Results

A total of 31 respondents (18 in Thailand and 13 in Myanmar) participated in the study. The main theme reported by participants was challenges in limited corroboration and coordination among stakeholders. Unstructured information sharing and lack of communication hindered the stakeholders from engaging in TB control. The respondents stressed that referral mechanisms across the border need to be strengthened. Other challenges were associated with increasing loss to follow up and subsequent MDR cases, constraints of service delivery, shortage of human resources, limited staff capacities within organizations and poor socioeconomic status of patients.

Conclusions

Health professionals face many challenges in effectively addressing TB control. Addressing the insufficient coordination and collaboration by strengthening bi-national collaborative mechanisms among health care organizations is an essential step in reducing the burden of disease. Additional support and resources from governmental and non-governmental agencies will be required to address the challenges.

Assessment of therapeutic responses to gametocytocidal drugs in Plasmodium falciparum malaria

Indirect clinical measures assessing anti-malarial drug transmission-blocking activity in falciparum malaria include measurement of the duration of gametocytaemia, the rate of gametocyte clearance or the area under the gametocytaemia-time curve (AUC). These may provide useful comparative information, but they underestimate dose-response relationships for transmission-blocking activity. Following 8-aminoquinoline administration P. falciparum gametocytes are sterilized within hours, whereas clearance from blood takes days. Gametocytaemia AUC and clearance times are determined predominantly by the more numerous female gametocytes, which are generally less drug sensitive than the minority male gametocytes, whereas transmission-blocking activity and thus infectivity is determined by the more sensitive male forms. In choosing doses of transmission-blocking drugs there is no substitute yet for mosquito-feeding studies.

Comprehensive identification of single nucleotide polymorphisms associated with beta-lactam resistance within pneumococcal mosaic genes

Traditional genetic association studies are very difficult in bacteria, as the generally limited recombination leads to large linked haplotype blocks, confounding the identification of causative variants. Beta-lactam antibiotic resistance in Streptococcus pneumoniae arises readily as the bacteria can quickly incorporate DNA fragments encompassing variants that make the transformed strains resistant. However, the causative mutations themselves are embedded within larger recombined blocks, and previous studies have only analysed a limited number of isolates, leading to the description of “mosaic genes” as being responsible for resistance. By comparing a large number of genomes of beta-lactam susceptible and non-susceptible strains, the high frequency of recombination should break up these haplotype blocks and allow the use of genetic association approaches to identify individual causative variants. Here, we performed a genome-wide association study to identify single nucleotide polymorphisms (SNPs) and indels that could confer beta-lactam non-susceptibility using 3,085 Thai and 616 USA pneumococcal isolates as independent datasets for the variant discovery. The large sample sizes allowed us to narrow the source of beta-lactam non-susceptibility from long recombinant fragments down to much smaller loci comprised of discrete or linked SNPs. While some loci appear to be universal resistance determinants, contributing equally to non-susceptibility for at least two classes of beta-lactam antibiotics, some play a larger role in resistance to particular antibiotics. All of the identified loci have a highly non-uniform distribution in the populations. They are enriched not only in vaccine-targeted, but also non-vaccine-targeted lineages, which may raise clinical concerns. Identification of single nucleotide polymorphisms underlying resistance will be essential for future use of genome sequencing to predict antibiotic sensitivity in clinical microbiology.

Streptococcus pneumoniae is carried asymptomatically in the nasopharyngeal tract. However, it is capable of causing multiple diseases, including pneumonia, bacteraemia and meningitis, which are common causes of morbidity and mortality in young children. Antibiotic treatment has become more difficult, especially that involving the group of beta-lactam antibiotics where resistance has developed rapidly. The organism is known to be highly recombinogenic, and this allows variants conferring beta-lactam resistance to be readily introduced into the genome. Identification of the specific genetic determinants of beta-lactam resistance is essential to understand both the mechanism of resistance and the spread of resistant variants in the pneumococcal population. Here, we performed a genome-wide association study on 3,701 isolates collected from two different locations and identified candidate variants that may explain beta-lactam resistance as well as discriminating potential genetic hitchhiking variants from potential causative variants. We report 51 loci, containing 301 SNPs, that are associated with beta-lactam non-susceptibility. 71 out of 301 polymorphic changes result in amino acid alterations, 28 of which have been reported previously. Understanding the determinants of resistance at the single nucleotide level will be important for the future use of sequence data to predict resistance in the clinical setting.

Treatment of suspected hyper-reactive malarial splenomegaly (HMS) in pregnancy with mefloquine

Malaria infections in pregnancy are associated with adverse outcomes for both mother and child. There are few data on hyper-reactive malarial splenomegaly, an aberrant immunological response to chronic or recurrent malaria in pregnancy. This retrospective assessment reviewed the impact of mefloquine treatment on pregnant women with suspected hyper-reactive malarial splenomegaly in an area of low malaria transmission in the 1990s, showing significant reductions in spleen size and anemia and anti-malarial antibody titers without any notable negative effect on treated women or their newborns.

High initiation and long duration of breastfeeding despite absence of early skin-to-skin contact in Karen refugees on the Thai-Myanmar border: a mixed methods study

Background

Early skin-to-skin contact (SSC) after birth is recommended as part of the United Nations Children’s Fund (UNICEF) baby friendly health initiative to promote optimum breastfeeding. This paper reports rates of breastfeeding initiation and duration in a low resource environment, where early SSC is not practised, and explores views of pregnant women and midwives surrounding breastfeeding and swaddling.

Methods

Data from records from a single hospital on the Thai-Myanmar border where refugee women gave birth during a one-year period (2010) were used to determine breastfeeding initiation rates and the time of the first breastfeed, and duration of breastfeeding of the previous alive child in multigravidae. Focus group discussions (FGD) were conducted to obtain information from pregnant women attending antenatal care about their intended or previous duration of breastfeeding and views on breastfeeding. Interviews with local midwives explored reasons for high rates of breastfeeding in this setting and the practice of newborn swaddling.

Results

Of 1404 live births in 2010 in Maela refugee camp there were 982 evaluable mother-newborn pairs, including 80 infants born before 37 weeks gestation. Initiation of breastfeeding within the first hour after birth and exclusive breastfeeding at discharge in term mother-newborn pairs was 91.2% (823/902) and 99.3% (896/902); and before 37 weeks gestation, 48.8% (39/80) and 98.8% (79/80). Reported duration of previous breastfeeding was 19 (range 2 to 72) months.

During FGD all primigravidae (n = 17) intended to breastfeed and all multigravidae (n = 33) had previously breastfed; expected or previous duration of feeding was for more than one year or longer. The major theme identified during FGD was breastfeeding is “good”. Women stated their intention to breastfeed with certainty. This certainty was echoed during the interviews with midwifery staff. SSC requires a delay in early swaddling that in Karen people, with animistic beliefs, could risk loss of the spirit of the newborn or attract malevolent spirits.

Conclusions

In a population with a strong culture of breastfeeding and robust breastfeeding practices, high rates of initiation and duration of breastfeeding were found despite a lack of early skin-to-skin contact. Local preferences, traditions and practices that protect, support and maintain high rates of breastfeeding should be promoted.

Quality of ultrasound biometry obtained by local health workers in a refugee camp on the Thai-Burmese border

OBJECTIVE

In a refugee camp on the Thai-Burmese border, accurate dating of pregnancy relies on ultrasound measurements obtained by locally trained health workers. The aim of this study was to substantiate the accuracy of fetal biometry measurements performed by locally trained health workers by comparing derived reference equations with those published for Asian and European hospitals.

METHODS

This prospective observational study included 1090 women who had a dating crown-rump length (CRL) scan and one study-appointed ultrasound biometry scan between 16 and 40 weeks of gestation. The average of two measurements of each of biparietal diameter, head circumference, abdominal circumference and femur length was used in a polynomial regression model for the mean and SD against gestational age (GA). The biometry equations obtained were compared with published equations of professional sonographers from Asian and European hospitals by evaluation of the SD and Z-scores of differences between models.

RESULTS

Reference equations of biometric parameters were found to fit cubic polynomial models. The observed SD values, for any given GA, of fetal biometric measurements obtained by locally trained health workers were lower than those previously reported by centers with professional sonographers. For nearly the entire GA range considered, the mean values of the Asian and European equations for all four biometric measurements were within the 90% expected range (mean ± 1.645 SD) of our equations.

CONCLUSION

Locally trained health workers in a refugee camp on the Thai-Burmese border can obtain measurements that are associated with low SD values and within the normal limits of published Asian and European equations. The fact that the SD values were lower than in other studies may be explained by the use of the average of two measurements, CRL dating or motivation of the locally trained sonographers.

Adverse effects of falciparum and vivax malaria and the safety of antimalarial treatment in early pregnancy: a population-based study

Background

The effects of malaria and its treatment in the first trimester of pregnancy remain an area of concern. We aimed to assess the outcome of malaria-exposed and malaria-unexposed first-trimester pregnancies of women from the Thai–Burmese border and compare outcomes after chloroquine-based, quinine-based, or artemisinin-based treatments.

Methods

We analysed all antenatal records of women in the first trimester of pregnancy attending Shoklo Malaria Research Unit antenatal clinics from May 12, 1986, to Oct 31, 2010. Women without malaria in pregnancy were compared with those who had a single episode of malaria in the first trimester. The association between malaria and miscarriage was estimated using multivariable logistic regression.

Findings

Of 48 426 pregnant women, 17 613 (36%) met the inclusion criteria: 16 668 (95%) had no malaria during the pregnancy and 945 (5%) had a single episode in the first trimester. The odds of miscarriage increased in women with asymptomatic malaria (adjusted odds ratio 2·70, 95% CI 2·04–3·59) and symptomatic malaria (3·99, 3·10–5·13), and were similar for Plasmodium falciparum and Plasmodium vivax. Other risk factors for miscarriage included smoking, maternal age, previous miscarriage, and non-malaria febrile illness. In women with malaria, additional risk factors for miscarriage included severe or hyperparasitaemic malaria (adjusted odds ratio 3·63, 95% CI 1·15–11·46) and parasitaemia (1·49, 1·25–1·78 for each ten-fold increase in parasitaemia). Higher gestational age at the time of infection was protective (adjusted odds ratio 0·86, 95% CI 0·81–0·91). The risk of miscarriage was similar for women treated with chloroquine (92 [26%] of 354), quinine (95 [27%) of 355), or artesunate (20 [31%] of 64; p=0·71). Adverse effects related to antimalarial treatment were not observed.

Interpretation

A single episode of falciparum or vivax malaria in the first trimester of pregnancy can cause miscarriage. No additional toxic effects associated with artesunate treatment occurred in early pregnancy. Prospective studies should now be done to assess the safety and efficacy of artemisinin combination treatments in early pregnancy.

Funding

Wellcome Trust and Bill & Melinda Gates Foundation.