malaria infection among schoolchildren in highland Rwanda

Background Plasmodium infection and malaria in school children are increasingly recognized as a relevant public health problem, but data on actual prevalence and health consequences are insufficient. The present study from highland southern Rwanda aimed at estimating infection prevalence among children attending school, at identifying associated factors and at assessing the clinical consequences of these infections. Methods In a survey including 12 schools in the Huye district of Rwanda, 1089 children aged 6–10 years were clinically and anthropometrically examined, malaria parasites were diagnosed by microscopy and PCR, haemoglobin concentrations were measured, and socio- economic and behavioural parameters as well as medical histories were obtained. Results Upon examination, the vast majority of children was asymptomatic (fever 2.7%). Plasmodium infection was detected in 22.4% (Plasmodium falciparum, 18.8%); 41% of these were submicroscopic. Independent predictors of infection included low altitude, higher age, preceding antimalarial treatment, and absence of electricity or a bicycle in the household. Plasmodium infection was associated with anaemia (mean haemoglobin difference of −1.2 g/dL; 95% CI, −0.8 to −1.5 g/dL), fever, underweight, clinically assessed malnutrition and histories of fever, tiredness, weakness, poor appetite, abdominal pain, and vomiting. With the exception of underweight, these conditions were also increased at submicroscopic infection. Conclusion Malaria infection is frequent among children attending school in southern highland Rwanda. Although seemingly asymptomatic in the vast majority of cases, infection is associated with a number of non-specific symptoms in the children´s histories, in addition to the impact on anaemia. This argues for improved malaria surveillance and control activities among school children

Research into the appearance and anthelminthic susceptibility of gastrointestinal nematodes of humans and pigs in Rwanda

Geohelminthen oder „Soil-transmitted Helminths“ (STH), namentlich Ascaris lumbricoides, Trichuris trichiura und die Hakenwürmer N. americanus und A. duodenale sind weltweit verbreitete, humanpathogene und zum Teil zoonotische Parasiten, die weltweit nahezu 1,2 Milliarden Menschen betreffen und eine große Gefahr für die öffentliche Gesundheit und besonders für Schulkinder darstellen. Ihre strategische Bekämpfung in vielen endemischen Ländern wird immer wichtiger. Am häufigsten betroffen sind Kinder im Vorschul- und Schulalter, was zu Leistungseinbußen bis hin zu Unterernährung und körperlicher Unterentwicklung führen kann. Eine präventive Chemotherapie wird in Ruanda seit 2008 ein- bis zweimal im Jahr an Schulkinder verabreicht und erreicht einen großen Anteil der Zielgruppe. Ziel dieser Arbeit war es, Stuhlproben von Schulkindern im Alter zwischen sechs und zehn Jahren aus zwölf Schulen und Kotproben von Schweinen der Subdistrikte der südlichen Provinz Ruandas vor Ort mikroskopisch mittels Mini-FLOTAC Verfahren auf das Vorkommen von Wurmeiern einer oder mehrerer der oben genannten STH Spezies zu untersuchen. Die Beurteilung der anthelminthischen Wirksamkeit erfolgte mittels Berechnung der Eizahlreduktion und der „Cure Rate“. Im Rahmen der Studie wurden im Jahre 2014 ca. 2000 Stuhlproben mikroskopisch analysiert, im Folgejahr 2015 weitere 400 aus vier der ursprünglich zwölf untersuchten Schulen. Die an der Studie teilnehmenden Kinder brachten am Tag der Entwurmung eine frische Stuhlprobe in die Schule mit. Nach Abgabe der Stuhlprobe wurde ihnen 2014 nach einer Allgemeinuntersuchung und Blutentnahme unter Aufsicht eine Tablette Albendazol (400 mg) verabreicht und sieben bis zehn Tage nach der Entwurmung wurden erneut frische Stuhlproben in den Schulen eingesammelt. 2015 wurde nach demselben Schema verfahren, allerdings wurden die Kinder nicht erneut klinisch untersucht oder eine Blutprobe genommen. Zusätzlich wurden 2014 aus jedem zugehörigen Dorf Kotproben von Schweinen gesammelt, die mit beprobten Kindern auf engem Lebensraum, meist in einer Umzäunung neben dem Haus, wohnten. Sie wurden ebenfalls via Mini- FLOTAC auf das Vorkommen von Wurmeiern (Ascaris suum, Trichuris suis, Magen-Darm-Strongyliden) untersucht. Für weiterführende Untersuchungen wurden Rückstellproben gesichert, aus denen im Anschluss im Labor in Berlin DNA extrahiert wurde, um auf molekularbiologischer Ebene nach Einzelnukleotidpolymorphismen (SNP) in β-Tubulin Genen von Ascaris sp. zu suchen. Die Gesamtprävalenz für Ascaris sp. lag bei Erstuntersuchung bei fast 40 %, sie sank nach der ersten Entwurmung auf knapp 13 %. Die mikroskopischen Ergebnisse in der vorliegenden Studie zeigten in neun von zehn Schulen eine verminderte Wirksamkeit des BZ Albendazol gegen Ascaris sp. Die FECR lag hier in allen betroffenen Schulen unter der von Vercruysse et al. (2011) vorgeschlagenen Schwelle, einzig in Mugogwe fanden wir eine FECR über 95% (99,56 %). Insgesamt schwankte die FECR zwischen null und 99,56 %. Die CRs schwankten zwischen 33 und 100 %. Die parasitologischen Befunde ließen sich molekularbiologisch nicht untermauern, es konnten in keiner der untersuchten Proben die bekannten, mit BZ- Resistenz assoziierten β- Tubulin- SNPs gefunden werden. Bei den Schweinen fanden wir Prävalenzen für Ascaris sp. von 18,5 bis 80,8 %, für T. suis von 0 bis 28,8 % und von den MDS von 72,2 bis 94,2 %. In den als städtisch geltenden Bezirken Ngoma und Tumba wurden zum Zeitpunkt unserer Untersuchung keine Schweine gehalten. Die Ergebnisse lassen den Schluss zu, dass es in der südlichen Provinz Ruandas durch die jährliche Entwurmung mittels Benzimidazolpräparaten zur Selektion resistenter Wurmpopulationen gekommen sein könnte und in Zukunft an Strategien zur Vermeidung weiteren Selektionsdrucks gearbeitet werden muss. Dies sollte eine Priorität in künftigen Präventionsprogrammen sein. Zur besseren Einschätzung der Gesamtprävalenz resistenter Populationen ist eine Ausdehnung der Studie auf das gesamte Land in regelmäßigen Abständen erforderlich. Es ist denkbar, dass die Mechanismen für die vorliegenden Resistenzen an anderen Positionen in β- Tubulin Genen oder in weiteren β- Tubulin Isotypen im Ascaris sp. Genom zu finden sind. Außerdem wäre es möglich, dass Ascaris sp. resistent durch metabolische Stoffwechselwege werden, die zu einer Reduzierung des aktiven Wirkstoffs im Wurm führen. Es bleibt weiteren Forschungen vorbehalten, die Mechanismen aufzudecken, die bei Ascaris sp. zu BZ Resistenz führen.Soil transmitted helminths (STHs), namely Ascaris lumbricoides, Trichuris trichiura and the hookworms A. duodenale and N. americanus are common parasites in almost two billion humans globally and pose a great threat to human health, especially in schoolchildren. Strategic treatment against STHs becomes increasingly important in many endemic countries. School children are particularly vulnerable and STHs can inhibit school performance or, in more severe cases, lead to malnutrition and growth stunting. In Rwanda, preventive chemotherapy is applied once or twice a year to school children and most members of the target group are regularly treated. In this present study, stool samples from school children aged six to ten years belonging to twelve schools and stool samples from pigs from the subdistricts of the southern province of Rwanda were examined using Mini-FLOTAC chamber to detect eggs of one or multiple of the STH species mentioned above. Fecal egg count reduction (FECR) and cure rate (CR) were calculated to assess whether worm populations in Rwanda showed any signs for development of resistance against benzimidazoles. In 2014, almost 2000 stool samples were examined. During the follow-up in the next year, additional 400 samples from four out of the twelve schools were collected and examined. Children which had been enrolled in the study brought a fresh stool sample to school, which was then collected. In 2014, the children were also clinically examined. Additionally, a blood sample was taken and finally the children were treated with Albendazol under supervision. A follow-up stool sample was collected seven to ten days after the first treatment. The same procedure was undertaken in 2015 but children were not again clinically examined nor had to provide a blood sample. In 2014, additional stool samples from pigs, living in sheds next to the house as the participating children, were collected and examined for eggs of Ascaris suum, Trichuris suis or gastrointestinal strongyles. For further investigations, samples were kept from which DNA was extracted in the laboratory in Berlin and molecular analysis of β-tubulin single nucleotide polymorphisms in Ascaris sp. was performed. The overall prevalence for Ascaris sp. before the first round of deworming was 40 %, it decreased to 13 % after treatment. The results of microscopy in the present study showed signs of reduced efficacy of the BZ albendazole in nine out of 10 examined schools. The FECR in the affected schools was significally below the treshold suggested by Vercruysse et al. (2011). Overall it ranged from zero to 99.56 %. The CRs ranged from 33 to 100 %. However, the molecular biological results were not in line with the microscopic results since in none of the analyzed samples SNPs associated with BZ resistance were found. The prevalence of Ascaris sp. in pigs ranged from 18,5 - 80,8 %, of T. suis from 0 - 28,8 % and prevalences of hookworm ranged from 72,2 – 94,2 %. In the as urban claimed villages of Ngoma and Tumba there were no pigs living at the time our study was conducted. The results of the study suggest that resistance might have developed in the southern province of Rwanda and treatment has to be adapted accordingly to prevent further selection of resistant worm populations. This should be a priority in future prevention programs. For better evaluation of the prevalence of resistant population, further research needs to be conducted throughout the entire country. As this study has failed to show any of the suggested SNPs associated with benzimidazole resistance, further investigations into the mechanisms of resistance in Ascaris sp. are suggested since it is possible that SNPs are found at other sites of the genome such as in additional β-tubulin isotypes. In addition, it is possible that BZ metabolism leads to resistance by reducing the concentration of active drug with the worms. Future research will be needed to identify the BZ resistance mechanisms in Ascaris sp

Reduced efficacy of albendazole against Ascaris lumbricoides in Rwandan schoolchildren

Control of human soil-transmitted helminths (STHs) relies on preventive chemotherapy of schoolchildren applying the benzimidazoles (BZ) albendazole or mebendazole. Anthelmintic resistance (AR) is a common problem in nematodes of veterinary importance but for human STHs, information on drug efficacy is limited and routine monitoring is rarely implemented. Herein, the efficacy of single dose albendazole (400 mg) was evaluated in 12 schools in the Huye district of Rwanda where Ascaris is the predominant STH. Ascaris eggs were detected by wet mount microscopy and the Mini-FLOTAC method to assess cure rate (CR) and faecal egg count reduction (FECR). Blood and faecal samples were analysed for co-infections with Plasmodium sp. and Giardia duodenalis, respectively. Ascaris positive samples collected before and after treatment were analysed for putatively BZ-resistance associated β-tubulin gene single nucleotide polymorphisms. The overall CR was 69.9% by Mini-FLOTAC and 88.6% by wet mount microscopy. The FECR was 75.4% and the 95% calculated confidence intervals were 50.4–87.8% using sample variance, 55.4–88.8% by bootstrapping, and 75.0–75.7% applying a Markov Chain Monte Carlo Bayesian approach. FECR varied widely between 0 and 96.8% for individual schools. No putative BZ-resistance associated polymorphisms were found in the four Ascaris β-tubulin isotype genes examined. Since FECR

Comment on “The optimal timing of post-treatment sampling for the assessment of anthelminthic drug efficacy against Ascaris infections in humans”

A recent publication by Levecke et al. (Int. J. Parasitol, 2018, 8, 67–69) provides important insights into the kinetics of worm expulsion from humans following treatment with albendazole. This is an important aspect of determining the optimal time-point for post treatment sampling to examine anthelmintic drug efficacy. The authors conclude that for the determination of drug efficacy against Ascaris, samples should be taken not before day 14 and recommend a period between days 14 and 21. Using this recommendation, they conclude that previous data (Krücken et al., 2017; Int. J. Parasitol, 7, 262–271) showing a reduction of egg shedding by 75.4% in schoolchildren in Rwanda and our conclusions from these data should be interpreted with caution. In reply to this, we would like to indicate that the very low efficacy of 0% in one school and 52–56% in three other schools, while the drug was fully efficient in other schools, cannot simply be explained by the time point of sampling. Moreover, there was no correlation between the sampling day and albendazole efficacy. We would also like to indicate that we very carefully interpreted our data and, for example, nowhere claimed that we found anthelmintic resistance. Rather, we stated that our data indicated that benzimidazole resistance may be suspected in the study population. We strongly agree that the data presented by Levecke et al. suggests that recommendations for efficacy testing of anthelmintic drugs should be revised.Peer Reviewe

Asymptomatic only at first sight: malaria infection among schoolchildren in highland Rwanda

Plasmodium infection and malaria in school children are increasingly recognized as a relevant public health problem, but data on actual prevalence and health consequences are insufficient. The present study from highland southern Rwanda aimed at estimating infection prevalence among children attending school, at identifying associated factors and at assessing the clinical consequences of these infections.; In a survey including 12 schools in the Huye district of Rwanda, 1089 children aged 6-10 years were clinically and anthropometrically examined, malaria parasites were diagnosed by microscopy and PCR, haemoglobin concentrations were measured, and socio-economic and behavioural parameters as well as medical histories were obtained.; Upon examination, the vast majority of children was asymptomatic (fever 2.7%). Plasmodium infection was detected in 22.4% (Plasmodium falciparum, 18.8%); 41% of these were submicroscopic. Independent predictors of infection included low altitude, higher age, preceding antimalarial treatment, and absence of electricity or a bicycle in the household. Plasmodium infection was associated with anaemia (mean haemoglobin difference of -1.2 g/dL; 95% CI, -0.8 to -1.5 g/dL), fever, underweight, clinically assessed malnutrition and histories of fever, tiredness, weakness, poor appetite, abdominal pain, and vomiting. With the exception of underweight, these conditions were also increased at submicroscopic infection.; Malaria infection is frequent among children attending school in southern highland Rwanda. Although seemingly asymptomatic in the vast majority of cases, infection is associated with a number of non-specific symptoms in the children´s histories, in addition to the impact on anaemia. This argues for improved malaria surveillance and control activities among school children