Epidemiology of polyparasitism with Taenia solium, schistosomes and soil-transmitted helminths in the co-endemic village of Malanga, Democratic Republic of Congo

Diagnosis of Schistosomiasis without a Microscope: Evaluating Circulating Antigen (CCA, CAA) and DNA Detection Methods on Banked Samples of a Community-Based Survey from DR Congo

Detection of Schistosoma eggs in stool or urine is known for its low sensitivity in diagnosing light infections. Alternative diagnostics with better sensitivity while remaining highly specific, such as real-time PCR and circulating antigen detection, are progressively used as complementary diagnostic procedures but have not yet replaced microscopy. This study evaluates these alternative methods for the detection of Schistosoma infections in the absence of microscopy. Schistosomiasis presence was determined retrospectively in 314 banked stool and urine samples, available from a previous survey on the prevalence of taeniasis in a community in the Democratic Republic of the Congo, using real-time PCR, the point-of-care circulating cathodic antigen (POC-CCA) test, as well as the up-converting particle lateral flow circulating anodic antigen (UCP-LF CAA) test. Schistosoma DNA was present in urine (3%) and stool (28%) samples, while CCA (28%) and CAA (69%) were detected in urine. Further analysis of the generated data indicated stool-based PCR and the POC-CCA test to be suitable diagnostics for screening of S. mansoni infections, even in the absence of microscopy. A substantial proportion (60%) of the 215 CAA-positive cases showed low antigen concentrations, suggesting that even PCR and POC-CCA underestimated the “true” number of schistosome positives.

Epidemiology of Schistosoma mansoni infection in Ituri Province, north-eastern Democratic Republic of the Congo

BACKGROUND

Schistosomiasis, caused by Schistosoma mansoni, is of great significance to public health in sub-Saharan Africa. In the Democratic Republic of Congo (DRC), information on the burden of S. mansoni infection is scarce, which hinders the implementation of adequate control measures. We assessed the geographical distribution of S. mansoni infection across Ituri province in north-eastern DRC and determined the prevailing risk factors.

METHODS/PRINCIPAL FINDINGS

Two province-wide, community-based studies were conducted. In 2016, a geographical distribution study was carried out in 46 randomly selected villages across Ituri. In 2017, an in-depth study was conducted in 12 purposively-selected villages, across the province. Households were randomly selected, and members were enrolled. In 2016, one stool sample was collected per participant, while in 2017, several samples were collected per participant. S. mansoni eggs were detected using the Kato-Katz technique. In 2017, a point-of-care circulating cathodic S. mansoni antigen (POC-CCA) urine test was the second used diagnostic approach. Household and individual questionnaires were used to collect data on demographic, socioeconomic, environmental, behavioural and knowledge risk factors. Of the 2,131 participants in 2016, 40.0% were positive of S. mansoni infection. Infection prevalence in the villages ranged from 0 to 90.2%. Of the 707 participants in 2017, 73.1% were tested positive for S. mansoni. Prevalence ranged from 52.8 to 95.0% across the health districts visited. Infection prevalence increased from north to south and from west to east. Exposure to the waters of Lake Albert and the villages' altitude above sea level were associated with the distribution. Infection prevalence and intensity peaked in the age groups between 10 and 29 years. Preschool children were highly infected (62.3%). Key risk factors were poor housing structure (odds ratio [OR] 2.1, 95% 95% confidence interval [CI] 1.02-4.35), close proximity to water bodies (OR 1.72, 95% CI 1.1-2.49), long-term residence in a community (OR 1.41, 95% CI 1.11-1.79), lack of latrine in the household (OR 2.00, 95% CI 1.11-3.60), and swimming (OR 2.53, 95% CI 1.20-5.32) and washing (OR 1.75, 95% CI 1.10-2.78) in local water bodies.

CONCLUSIONS/SIGNIFICANCE

Our results show that S. mansoni is highly endemic and a major health concern in Ituri province, DRC. Infection prevalence and intensity, and the prevailing socioeconomic, environmental, and behavioural risk factors in Ituri reflect intense exposure and alarming transmission rates. A robust plan of action is urgently needed in the province.

Case Report: Three Cases of Neurocysticercosis in Central Africa

Neurocysticercosis (NCC) is an infection prevalent in developing countries; however, it is neglected in the Democratic Republic of the Congo (DRC) and in sub-Saharan Africa. Here, we present three different cases seen in a consulting room in Lubumbashi. These cases are evidence that NCC is more common than it was previously thought in sub-Saharan Africa. Neurocysticercosis is a pathology-neglected and ignored infection, not only by the population but also by health professionals and health authorities in the DRC, and because of that, it is important to increase the research about NCC in the DRC to assess the prevalence and risk factors for NCC to assess the severity of the phenomenon and to help designing appropriate prevention and control measures.

Community-based survey on helminth infections in Kwilu province, the Democratic Republic of the Congo, and implications for local control strategies

To adequately plan mass drug administration campaigns, the Democratic Republic of the Congo (DRC) needs further support for the mapping and monitoring of schistosomiasis (SCH) and soil-transmitted helminths (STH). We conducted a community-based survey in the health districts of Mosango and Yasa Bonga of the Kwilu province, DRC. A stratified two-stage cluster random sampling method was used to include participants into three different strata: Preschool-aged children (PSAC), school-aged children (SAC), and adults who were further subdivided into women of reproductive age (WRA) and other adults. In total, surveyors visited 30 villages, and 1 206 individuals participated in the study. Stool samples were collected to perform duplicate Kato-Katz smears for the detection of SCH and STH infection. Hookworm was the most prevalent infection in both districts, 34.1% (95%CI: 32.0–38.4), followed by A. lumbricoides (2.7%; 95%CI: 1.3–2.9) and T. trichiura (1.9%; 95%CI: 1.1–2.7). We did not find any SCH infection. The prevalence of each STH infection was similar across all risk groups, and the majority of the infected individuals was carrying light intensity infection. Compared to SAC, other adults were equally infected with hookworm. The prevalence of STH infection in SAC guides the MDA implementation because schoolchildren are most at risk and easily accessible program targets if school attendance is high. The current treatment strategy targets PSAC, SAC and WRA. However, this study shows that adults in general could also benefit from deworming. Therefore, community-wide preventive chemotherapy would be the most appropriate choice to control the hookworm burden rapidly.

Helminths are a group of intestinal worms that cause abdominal discomfort, diarrhea, and anemia due to blood loss in the stool. Regular mass drug administration (MDA) is one strategy to fight these worm infections. The appropriate MDA treatment scheme is chosen based on a population survey estimating the burden of infection. This survey is usually done in schoolchildren because they suffer the most from these infections and they are easy to reach through school infrastructures. However, one particular worm, the hookworm, is also highly present and clinically relevant in adults. We conducted a community-based survey in two districts of the Kwilu Province of the DRC. We found that hookworm was the predominant infection in the area and that adults were as often infected as the schoolchildren. Therefore, to effectively reduce hookworm infection, we advise extending treatment schemes to the entire community.

Amoebic toxic megacolon with poly-helminthic coinfection: Case presentation and review of intestinal polyparasitic infections

INTRODUCTION

Intestinal parasitic infections are a health burden to developing countries, but can also become more prevalent worldwide, even in developed countries, with the advent of globalization. While most of these infections are benign, some may be associated with acute infections with high morbidity and mortality rates.

CASE PRESENTATION

A 36 years old patient presented with toxic megacolon with poly-helminthic infections, likely a result of raw food ingestion. She subsequently required multiple surgeries with a total colectectomy and small bowel resection, and ended up with an end-ileostomy.

DISCUSSION

Intestinal polyparasitism has been reported in undeveloped countries, but it appears that such a trend can be found in developed countries as well. Clinicians, especially those practicing in countries with large expatriate or immigrant worker populations, should be aware of this trend and adjust treatment protocols accordingly.

CONCLUSION

Even in countries whereby intestinal parasitic infections are not common, clinicians should have a heightened awareness of the possibility for such infections to be present, especially in returning travellers, expatriate or immigrant populations.

The extent, nature, and pathogenic consequences of helminth polyparasitism in humans: A meta-analysis

Background

Individual helminth infections are ubiquitous in the tropics; geographical overlaps in endemicity and epidemiological reports suggest areas endemic for multiple helminthiases are also burdened with high prevalences of intestinal protozoan infections, malaria, tuberculosis (TB), and human immunodeficiency virus (HIV). Despite this, pathogens tend to be studied in isolation, and there remains a need for a better understanding of the community ecology and health consequences of helminth polyparasitism to inform the design of effective parasite control programs.

Methodology

We performed meta-analyses to (i) evaluate the commonality of polyparasitism for helminth-helminth, helminth-intestinal protozoa, helminth-malaria, helminth-TB, and helminth-HIV co-infections, (ii) assess the potential for interspecies interactions among helminth-helminth and helminth-intestinal protozoan infections, and (iii) determine the presence and magnitude of association between specific parasite pairs. Additionally, we conducted a review of reported health consequences of multiply-infected individuals compared to singly- or not multiply-infected individuals.

Principal findings

We found that helminth-helminth and helminth-intestinal protozoan multiple infections were significantly more common than single infections, while individuals with malaria, TB, and HIV were more likely to be singly-infected with these infections than co-infected with at least one helminth. Most observed species density distributions significantly differed from the expected distributions, suggesting the potential presence of interspecies interactions. All significant associations between parasite pairs were positive in direction, irrespective of the combination of pathogens. Polyparasitized individuals largely exhibited lower hemoglobin levels and higher anemia prevalence, while the differences in growth-related variables were mostly statistically insignificant.

Conclusions

Our findings confirm that helminth polyparasitism and co-infection with major diseases is common in the tropics. A multitude of factors acting at various hierarchical levels, such as interspecies interactions at the within-host infra-parasite community level and environmental variables at the higher host community level, could explain the observed positive associations between pathogens; there remains a need to develop new frameworks which can consider these multilevel factors to better understand the processes structuring parasite communities to accomplish their control.

Helminth infections are a highly prevalent global health problem. These parasitic worm infections occur in areas also burdened with intestinal protozoan infections, malaria, tuberculosis, and human immunodeficiency virus. While these pathogens tend to be studied in isolation, there remains a need to better understand the nature, extent, and health consequences of helminth polyparasitism and co-infection with major diseases. Here, we reviewed the literature and performed meta-analyses to evaluate the commonality of helminth polyparasitism and co-infection, the potential for interspecies interactions between parasites, the association between parasite pairs, and the health consequences among multiply-infected individuals. We confirmed that polyparasitism and co-infection with major diseases are common in the global South and found that multiply-infected individuals experienced worse health consequences when compared to singly or not-multiply infected individuals. Our analysis suggested the potential presence of interspecies interactions and we identified the existence of positive associations between parasite pairs. These findings support the call for integrating deworming into malaria, TB, and HIV treatment protocols and suggest there remains a need to improve our understanding of the factors influencing co-transmission to achieve sustainable parasite control.

The Advances in Molecular and New Point-of-Care (POC) Diagnosis of Schistosomiasis Pre- and Post-praziquantel Use: In the Pursuit of More Reliable Approaches for Low Endemic and Non-endemic Areas

Like soil-transmitted helminth infections, schistosomiasis is an important neglected tropical disease (NTD) related to poverty with a major impact on public health in developing countries. Diagnosis of active infection is crucial for surveillance of controlled or post-elimination schistosomiasis areas. In addition, the use of conventional diagnostic tools in non-exposed populations (such as travelers) results in misdiagnoses in the prepatent period of infection. Also, the accuracy of standard tests applied in low-endemicity areas (LEAs) decreases after several rounds of treatment. We aimed to determine whether it would be necessary to replace schistosomiasis conventional diagnostic tests such as parasitological methods in LEAs. Also, we evaluate the use of new tools in non-endemic areas. Reliable, cheap and easy-to-use diagnostic tools are needed to respond to the demands of a new era of elimination and eradication of schistosomiasis. To this end, molecular diagnosis-including nucleic acid-based assays (loop-mediated isothermal amplification, polymerase chain reaction) and circulating cathodic and anodic antigen detection tests have become promising strategies. In this review, we attempt to address the use of alternative diagnostic tests for active infection detection and drug-monitoring after specific schistosomiasis treatment.

Polyparasitism and zoonotic parasites in dogs from a rural area of the Argentine Chaco

Dogs play an important role as reservoirs and hosts of multiple pathogens shared with humans and wildlife, which contribute significantly to the global burden of disease. Here, we assessed the occurrence of a broad range of zoonotic and non-zoonotic parasites in dogs from a rural area in the humid Chaco; determined the occurrence of polyparasitism; and explored its association with selected risk factors. In total, 212 dogs were examined serologically to determine Trypanosoma cruzi infection and 152 of them also were examined for Ehrlichia canis, Borrelia bugderfori, Anaplasma phagocitophylum, Dirofilaria immitis and Toxoplasma gondii. Fecal samples from 85 dogs were examined for intestinal parasites. Seventeen parasite species were seen, 77% of which are zoonotic. The most prevalent parasites were Ancylostoma caninum (68.2%), T. gondii (55.3%, first report for dogs in Argentina), Giardia sp. (25.9%), Cryptosporidium sp. (20.0%), T. cruzi (16.5%), trematodes (15.3%) and Toxocara canis (14.1%). Polyparasitism was found in 96% of the dogs, with up to six parasite species in a single dog, and was significantly associated with age of dog but not with host body condition or sex. The most frequent pair of parasites found together were T. gondii-A. caninum (46%), A. caninum-T. cruzi (34%) and T. gondii-T. cruzi (27%). The prevalence of anemia and leukocytosis was significantly higher in dogs showing the worst body condition. Our findings likely reflect structural poverty, poor sanitation and lack of a safe water supply. Importantly, many of the prevalent parasites seen are threats to human health. 243 words.

A comparative analysis of preservation techniques for the optimal molecular detection of hookworm DNA in a human fecal specimen

BACKGROUND

Proper collection and storage of fecal samples is necessary to guarantee the subsequent reliability of DNA-based soil-transmitted helminth diagnostic procedures. Previous research has examined various methods to preserve fecal samples for subsequent microscopic analysis or for subsequent determination of overall DNA yields obtained following DNA extraction. However, only limited research has focused on the preservation of soil-transmitted helminth DNA in stool samples stored at ambient temperature or maintained in a cold chain for extended periods of time.

METHODOLOGY

Quantitative real-time PCR was used in this study as a measure of the effectiveness of seven commercially available products to preserve hookworm DNA over time and at different temperatures. Results were compared against "no preservative" controls and the "gold standard" of rapidly freezing samples at -20°C. The preservation methods were compared at both 4°C and at simulated tropical ambient temperature (32°C) over a period of 60 days. Evaluation of the effectiveness of each preservative was based on quantitative real-time PCR detection of target hookworm DNA.

CONCLUSIONS

At 4°C there were no significant differences in DNA amplification efficiency (as measured by Cq values) regardless of the preservation method utilized over the 60-day period. At 32°C, preservation with FTA cards, potassium dichromate, and a silica bead two-step desiccation process proved most advantageous for minimizing Cq value increases, while RNA later, 95% ethanol and Paxgene also demonstrate some protective effect. These results suggest that fecal samples spiked with known concentrations of hookworm-derived egg material can remain at 4°C for 60 days in the absence of preservative, without significant degradation of the DNA target. Likewise, a variety of preservation methods can provide a measure of protection in the absence of a cold chain. As a result, other factors, such as preservative toxicity, inhibitor resistance, preservative cost, shipping requirements, sample infectivity, and labor costs should be considered when deciding upon an appropriate method for the storage of fecal specimens for subsequent PCR analysis. Balancing logistical factors and the need to preserve the target DNA, we believe that under most circumstances 95% ethanol provides the most pragmatic choice for preserving stool samples in the field.

Intestinal cestodes

PURPOSE OF REVIEW

Cestodes infections in humans are among the most prevalent parasitosis worldwide. Although tapeworm infection is often asymptomatic, they can be associated with a range of symptoms. The landscape of cestode infections is changing with rapid diagnosis techniques and advanced molecular diagnosis aiding in identification of species specific epidemiology.

RECENT FINDINGS

Traditional descriptions of species by location have been challenged with molecular diagnostic techniques, which show variation in distribution of species, thought to be because of globalization and importation of disease.

MAIN THEMES IN LITERATURE

Epidemiology, molecular diagnostic techniques.

SUMMARY

Infection by tapeworms is often asymptomatic or accompanied by mild symptoms though can occasionally cause severe disease and contribute to anemia and malnutrition. Tapeworm infection is most prevalent in resource-poor countries but the distribution is worldwide. Epidemiology of infection is changing because of molecular diagnostics, which allow more accurate tracking of species.

Assessment of schistosomiasis and soil-transmitted helminths prevalence in school-aged children and opportunities for integration of control in local health services in Kwilu Province, the Democratic Republic of the Congo

OBJECTIVE

To determine the prevalence of schistosomiasis (SCH) and soil-transmitted helminths (STH) in the Democratic Republic of Congo, and to assess the capacity of the local health centres for diagnosis and treatment.

METHODS

Cross-sectional school-based survey in two health districts in the Province of Kwilu. We collected a stool and a urine sample for parasitological examination. Urine filtration and duplicate Kato-Katz thick smears were used for the diagnosis of SCH. Health centres were evaluated using a structured questionnaire.

RESULTS

In total, 526 children participated in the study and the overall prevalence of Schistosoma mansoni infection was 8.9% (95% CI: 3.5-13.2) in both districts. The prevalence was higher in Mosango (11.7%; 95% CI: 8.9-14.8) than Yasa Bonga district (6.2%; 95% CI: 1.1-11.4). Urine filtration showed that Schistosoma haematobium infection was not present. The combined STH infection prevalence was 58.1% in both districts; hookworm infection was the most common STH found in 52.9% (95% CI: 29.3-62.4) of subjects, followed by Ascaris lumbricoides 9.3% (95% CI: 5.8-15.5) and Trichuris trichiura 2.1% (95% CI: 0.9-4.9). Mixed STH infections were observed as well as SCH-STH coinfection.

CONCLUSION

Further mapping of both SCH and STH burden is needed, and coverage of preventive chemotherapy in school-aged children should be increased.

Neurocysticercosis: A case study of a Mongolian traveler who visited China and India with an updated review in Asia

BACKGROUND

Neurocysticercosis (NCC) of Taenia solium has never been reported in Mongolia. A Mongolian traveler who visited China and India presented with epileptic seizures after his return to Mongolia. Magnetic resonance imaging showed multiple ring enhancing lesions with edema surrounding several lesions in his brain that were initially diagnosed to be viral encephalitis or NCC.

METHODS

Serology for cysticercosis using diagnostic antigens partially purified by cation-exchange chromatography and chimeric recombinant antigens and DNA analysis of a proglottid found in the patient's stool were applied for differential diagnosis.

RESULTS

Serology showed strong positivity for NCC, and mitochondrial cox1 gene analysis revealed Indian but not Chinese haplotype of T. solium.

CONCLUSION

This NCC case was considered to be caused by eggs released from adult tapeworm(s) established after eating uncooked or undercooked pork contaminated with cysticerci during his stay in India. This is a case report of taeniasis and secondary NCC associated with travel to India with an updated review of NCC in Asia. Molecular tracking of the specimen is highly informative as a way to identify where the infection was acquired.