A genome-wide map of DNA replication at single-molecule resolution in the malaria parasite Plasmodium falciparum.

The malaria parasite Plasmodium falciparum replicates via schizogony: an unusual type of cell cycle involving asynchronous replication of multiple nuclei within the same cytoplasm. Here, we present the first comprehensive study of DNA replication origin specification and activation during Plasmodium schizogony. Potential replication origins were abundant, with ORC1-binding sites detected every ∼800 bp. In this extremely A/T-biased genome, the sites were biased towards areas of higher G/C content, and contained no specific sequence motif. Origin activation was then measured at single-molecule resolution using newly developed DNAscent technology: a powerful method of detecting replication fork movement via base analogues in DNA sequenced on the Oxford Nanopore platform. Unusually, origins were preferentially activated in areas of low transcriptional activity, and replication forks also moved fastest through lowly transcribed genes. This contrasts with the way that origin activation is organised in other systems, such as human cells, and suggests that P. falciparum has evolved its S-phase specifically to minimise conflicts between transcription and origin firing. This may be particularly important to maximise the efficiency and accuracy of schizogony, with its multiple rounds of DNA replication and its absence of canonical cell-cycle checkpoints.

Plasmodium falciparum GBP2 Is a Telomere-Associated Protein That Binds to G-Quadruplex DNA and RNA.

In the early-diverging protozoan parasite Plasmodium, few telomere-binding proteins have been identified and several are unique. Plasmodium telomeres, like those of most eukaryotes, contain guanine-rich repeats that can form G-quadruplex structures. In model systems, quadruplex-binding drugs can disrupt telomere maintenance and some quadruplex-binding drugs are potent anti-plasmodial agents. Therefore, telomere-interacting and quadruplex-interacting proteins may offer new targets for anti-malarial therapy. Here, we report that P. falciparum GBP2 is such a protein. It was identified via 'Proteomics of Isolated Chromatin fragments', applied here for the first time in Plasmodium. In vitro, PfGBP2 binds specifically to G-rich telomere repeats in quadruplex form and it can also bind to G-rich RNA. In vivo, PfGBP2 partially colocalises with the known telomeric protein HP1 but is also found in the cytoplasm, probably due to its affinity for RNA. Consistently, its interactome includes numerous RNA-associated proteins. PfGBP2 is evidently a multifunctional DNA/RNA-binding factor in Plasmodium.

Sentinel surveillance of soil-transmitted helminthiasis in preschool-aged and school-aged children in selected local government units in the Philippines: follow-up assessment.

This study was a follow-up to the baseline nationwide survey of soil-transmitted helminth (STH) infections in preschool-aged children in the Philippines and in school-aged children in selected sentinel sites to assess the Integrated Helminth Control Program of the Department of Health. The objective of the study was to describe the current prevalence and intensity of STH infections in preschool-aged and school-aged children in 6 sentinel provinces and to compare these data with baseline findings. A cross-sectional study design was used to determine the prevalence and intensity of STH infections. Parasitological assessment involved the examination of stool samples by the Kato-Katz method. Although parasitological parameters in the 2 age groups at follow-up showed significant reductions from the baseline, these parameters remained high despite 3 years of mass drug administration (MDA). Efforts toward achieving high MDA coverage rates, provision of clean water, environmental sanitation, and promotion of hygiene practices must be prioritized.

Improving current helminth control strategies: Lessons from a baseline prevalence survey of soil-transmitted helminth infections in adolescent females and pregnant women in selected local government units in the Philippines

OBJECTIVES: This study utilized a cross-sectional study design to determine the prevalence and intensity of STH infections among adolescent females and pregnant women, to describe the nutritional status of the two population groups in selected study sites in the Philippines, and to propose a scheme for classification of endemic sites as basis for conduct of control strategies. METHODS: Parasitologic assessment was conducted through examination of collected stool samples using the Kato-Katz technique, while nutritional status was assessed through primary height and weight measurements.RESULTS: Results of the parasitologic assessment in adolescent females showed an overall cumulative prevalence of 30.4% (12.5% - 61.8%) and a prevalence of heavy intensity infection of 7.9% (0.7% - 22.6%). In pregnant women, overall cumulative prevalence was 31.5% (13.2% - 75.8%) and prevalence of heavy intensity infection was 10.2% (0.9%- 39.6%). CONCLUSION: Significant differences in prevalence in the different sentinel sites suggest the need to consider a modified classification scheme for endemic communities to determine the most cost-effective strategies for morbidity control. The utilization of this classification scheme alongside regular sentinel surveillance will help validate the scheme and contribute towards the development of more appropriate program guidelines for nationwide implementation.

Fear of birth defects is a major barrier to soil-transmitted helminth treatment (STH) for pregnant women in the Philippines.

The World Health Organization recommends anthelminthic treatment for pregnant women after the first trimester in soil-transmitted helminth (STH) endemic regions to prevent adverse maternal-fetal consequences. Although studies have shown the high prevalence of infection in the Philippines, no research has evaluated deworming practices. We hypothesized that pregnant women are not receiving deworming treatment and we aimed to identify barriers to World Health Organization guideline implementation. We conducted key informant interviews with local Department of Health (DOH) administrators, focus group discussions with nurses, midwives, and health care workers, and knowledge, attitudes, and practices surveys with women of reproductive age to elicit perspectives about deworming during pregnancy. Key informant interviews revealed that healthcare workers were not deworming pregnant women due to inadequate drug supply, infrastructure and personnel as well as fear of teratogenicity. Focus group discussions showed that healthcare workers similarly had not implemented guidelines due to infrastructure challenges and concerns for fetal malformations. The majority of local women believed that STH treatment causes side effects (74.8%) as well as maternal harm (67.3%) and fetal harm (77.9%). Women who were willing to take anthelminthics while pregnant had significantly greater knowledge as demonstrated by higher Treatment Scores (mean rank 146.92 versus 103.1, z = -4.40, p<0.001) and higher Birth Defect Scores (mean rank 128.09 versus 108.65, z = -2.43, p = 0.015). This study concludes that World Health Organization guidelines are not being implemented in the Philippines. Infrastructure, specific protocols, and education for providers and patients regarding anthelminthic treatment are necessary for the successful prevention of STH morbidity and mortality among pregnant women.

Integrated surveillance of pulmonary tuberculosis and paragonimiasis in Zamboanga del Norte, the Philippines.

BACKGROUND: Pulmonary tuberculosis (PTB) and paragonimiasis remain as health problems in certain areas in the Philippines. Both share similar clinical manifestations, which include chronic productive cough, hemoptysis, dyspnea, fever, weight loss, and night sweats. This study aimed to determine the prevalence of PTB, paragonimiasis, and co-infections in Zamboanga del Norte, Philippines. METHODS: This study was conducted in selected villages in two municipalities in Zamboanga del Norte. Patients with chronic cough were interviewed, examined, and requested to submit two sputum samples which were processed using Ziehl-Neelsen method to detect acid-fast bacilli (AFB), and NaOH concentration technique for the detection of Paragonimus ova. RESULTS: A total of 836 patients submitted sputum samples for examination. Prevalence was 6·7% (2·5-12·7%) for paragonimiasis and 1·9% (0·9-6·3%) for PTB. Co-infection rate was 0·3%, with two identified cases. Positivity rates for males and females were 9·6 and 5·8% for paragonimiasis and 3·4 and 1·2% for PTB. CONCLUSION: Pulmonary tuberculosis and paragonimiasis are co-endemic in Zamboanga del Norte, suggesting the need to integrate surveillance and control efforts. Strengthening local health systems through collaboration between different sectors is recommended for effective disease control. Development of more sensitive diagnostic tests is important for more accurate disease surveillance.

Monitoring the impact of a mebendazole mass drug administration initiative for soil-transmitted helminthiasis (STH) control in the Western Visayas Region of the Philippines from 2007 through 2011.

School-aged children in tropical developing countries carry the highest burden of soil-transmitted helminth (STH) infections in the world. The Western Visayas region of the Philippines continues to struggle with this as a major public health issue in both private and public schools. The War on Worms-Western Visayas approach was launched in 2007 with school-based mass drug administration (MDA) as one of the strategies to control morbidity from STH in support of the Department of Health - Integrated Helminth Control Program. This study aimed to determine trends in prevalence and intensity of STH infections as well as to assess related morbidity and program sustainability through 2011. A cross-sectional parasitologic survey was conducted on three independent samples of Grade 3 students in 2007, 2009, and 2011. Supporting aggregate data were obtained for MDA coverage, National Achievement Test mean percentage scores, and nutritional status. Tests for trend were utilized to detect changes in prevalence over time, with a particular emphasis on trends seen between 2009 and 2011. The initial impact of the program was robust as cumulative prevalence, infection intensities, and parasite densities were all reduced four years following the launch. However, subsequent and significant increases in each were found from 2009 until 2011. These results implicate issues with program sustainability, despite consistent MDA, and existing frameworks for environmental sanitation, hygiene, and education.

Soil-transmitted helminth and other intestinal parasitic infections among school children in indigenous people communities in Davao del Norte, Philippines.

A significant portion of the population in the Philippines consists of indigenous people (IP) groups, approximately 9% or 8.1 million. Data on the health status of these groups are very limited including the status of soil-transmitted helminth (STH) infections. Provision of such data will be of great importance in the formulation of policy on control and prevention of these diseases in this group. This study was conducted in selected villages/barangays in the municipalities of Carmen, Kapalong, San Isidro and Sto. Tomas in the Province of Davao del Norte in Southern Mindanao, Philippines. Parasitologic assessment was performed using Kato-Katz to qualify and quantify STH infections, while nutritional status assessment was based on hemoglobin determination and on nutritional status indicators, i.e., weight-for-age (WFA), height-for-age (HFA), and body mass index (BMI) for age derived from anthropometric measurements. A total of 572 school children participated in the survey, 264 (46.2%) of whom belonged to a specific IP group. Results showed that 34.1% of the school children had at least one STH infection while 5.9% had heavy intensity infections. Cumulative prevalence in IP school children was significantly higher than in non-IP children with rates at 39.0% and 29.9%, respectively (P = 0.021). Overall prevalence of school children with below normal WFA was 29.9%, while prevalence of those with below normal HFA and BMI for age was 42.8% and 14.9%, respectively. Of those examined, 8.3% had below normal hemoglobin levels. There was no significant difference observed between the nutritional status parameters of IP and non-IP school children. The parasitologic parameters reported in this study signify the need to pay more attention to IP children who are at higher risk of morbidity due to helminth infections. Access of IP communities to quality health services, which include mass drug administration (MDA) and health education on a regular basis, must be ensured. Further studies to determine factors that contribute to the higher prevalence of STH among IP groups are recommended.

Impact of a local government unit supported school-based initiative for control of intestinal helminth infections

Objectives. This study aimed to describe baseline and follow-up prevalence and intensity of soil-transmitted helminth (STH) infections, nutritional status and school performance of school-age children in Cebu City. By measuring these parameters, it also aimed to monitor the progress of a local government unit-led, school-based, schoolteacher-assisted deworming initiative. Methods. Grade three and grade four pupils from two selected school districts in Cebu City were chosen as participants. Kato-Katz technique was used to assess helminth infections. All positive slides and 10% of all negative slides were re-examined blindly by a reference microscopist for quality control. Secondary anthropometric and school performance data were also obtained from the Department of Education. Results. Baseline results showed cumulative prevalence and prevalence of heavy intensity infection of 73.1% and 44.3%, respectively, which were significantly lower during follow-up at 56.5% (p < 0.0001) and 26.5% (p < 0.0001), respectively. School performance improved in District B, with an 8.8% increase in mean percentage score from baseline to follow-up. There was no marked difference between baseline and follow-up proportions of pupils with below normal weight-for-age and height-for-age. Conclusions. The positive results merit continuation of the school-based STH control initiative in Cebu City. Improvements in water supply and sanitation, promotion of good hygiene and health education are important in minimizing risks of infection and re-infection.