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Parasites & Vectors Dec 2023Loiasis is endemic in the northern and western part of the Republic of Congo. Between 2004 and 2010, surveys were conducted, using the RAPLOA method, in all departments...
BACKGROUND
Loiasis is endemic in the northern and western part of the Republic of Congo. Between 2004 and 2010, surveys were conducted, using the RAPLOA method, in all departments of the Republic of Congo to assess the distribution of loiasis. Prior to 2004, only two parasitological surveys on loiasis had been conducted in Congo and mainly in the Department of Lékoumou, in the southwestern of the country. In 2019, we conducted a parasitological survey in this same department, more than 30 years after the first surveys.
METHODS
The study was conducted in 21 villages. Loa loa and Mansonella perstans microfilaremia levels were quantified using 50 µl calibrated blood smears.
RESULTS
A total of 2444 individuals were examined. The median age of the screened individuals was 43 (interquartile range: 30-57, range: 18-91) years old. The overall prevalences of L. loa and M. perstans microfilaremia were 20.0% [95% confidence intervals (CI) 18.0-21.6%] and 1.0% (95% CI 0.6-1.4%) respectively. The proportion of individuals with a microfilarial density of L. loa > 8000 mf/ml and > 30,000 mf/ml were 5.1% (95% CI 4.3-6.1%) and 1.1% (95% CI 0.8-1.7%), respectively. The overall community microfilarial load was 3.4 mf/ml.
CONCLUSIONS
Prevalences and intensities of L. loa infection remained generally stable between the late 1980s and 2019 in the Lékoumou Department. In contrast, parasitological indicators for M. perstans have declined sharply in the intervening years for an unknown reason.
Topics: Animals; Humans; Adult; Middle Aged; Mansonella; Loiasis; Mansonelliasis; Loa; Congo; Prevalence; Microfilariae
PubMed: 38071391
DOI: 10.1186/s13071-023-06056-w -
PloS One 2024Mansonella spp. have been reported to have a wide global distribution. Despite the distribution and co-occurrence with other filarial parasites like Wuchereria...
Mansonella spp. have been reported to have a wide global distribution. Despite the distribution and co-occurrence with other filarial parasites like Wuchereria bancrofti, Onchocerca volvulus and Loa loa, it is given little attention. There are few surveillance programmes for assessing the distribution of mansonellosis, due to the associated mild to no symptoms experienced by infected people. However, addressing this infection is critical to the onchocerciasis control program as current rapid diagnostic tools targeting O. volvulus have the tendency to cross react with Mansonella species. In this study we identified and characterised M. perstans from five sites in two districts in the Volta Region of Ghana and compared them to samples from other regions. Night blood smears and filter blood blots were obtained from individuals as part of a study on lymphatic filariasis. The Giemsa-stained smears were screened by microscopy for the presence of filarial parasites. Genomic DNA was extracted from blood blots from 39 individuals that were positive for M. perstans and Nested PCR targeting the internal spacer 1 (ITS-1) was conducted. Of these, 30 were sequenced and 24 sequences were kept for further analysis. Phylogenetic analysis of 194 nucleotide positions showed no differences in the samples collected. The similarities suggests that there could be one species in this area. However, more robust studies with larger sample sizes are required to draw such conclusions. We also observed a clustering of the samples from Ghana with reference sequences from Africa and Brazil, suggesting they could be related. This study draws further attention to a neglected infection, presents the first characterisation of M. perstans in Ghana and calls for more population-based studies across different geographical zones to ascertain species variations and disease distribution.
Topics: Ghana; Mansonella; Humans; Mansonelliasis; Animals; Phylogeny; Male; Female
PubMed: 38848396
DOI: 10.1371/journal.pone.0295089 -
European Journal of Microbiology &... Sep 2023Mansonellosis is a widely neglected helminth disease which is predominantly observed in tropical regions. This study was conducted to assess potential associations of...
BACKGROUND
Mansonellosis is a widely neglected helminth disease which is predominantly observed in tropical regions. This study was conducted to assess potential associations of the prevalence of circulating Mansonella perstans-specific cell-free DNA in human serum and HIV infection in Ghanaian individuals.
METHODS
For this purpose, serum samples obtained from Ghanaian HIV-patients (n = 989) and non-HIV-infected Ghanaian control individuals (n = 91) were subjected to real-time PCR targeting the ITS-(internal transcribed spacer-)2 sequence of M. perstans and Mansonella sp. Deux.
RESULTS
Mansonella-specific cell-free DNA was detected in serum samples of only 2 HIV-positive and 0 HIV-negative individuals, making any reliable conclusions on potential associations between HIV and mansonellosis in tropical Ghana unfeasible.
CONCLUSIONS
Future epidemiological studies on hypothetical associations between mansonellosis and HIV infections should focus more specifically on high-endemicity settings for both Mansonella spp.-infections and HIV-infections, include higher case numbers and be based on real-time PCR from whole blood rather than from serum, in which only circulating parasite DNA but no more cell-bound parasite DNA can be detected. However, the study did not show associations of HIV infections in Ghanaian individuals with Mansonella worm loads high enough to detect cell-free Mansonella DNA in serum by PCR.
PubMed: 37751320
DOI: 10.1556/1886.2023.00028 -
Brain Communications 2023Nodding syndrome is a neglected, disabling and potentially fatal epileptic disorder of unknown aetiology affecting thousands of individuals mostly confined to Eastern...
Nodding syndrome is a neglected, disabling and potentially fatal epileptic disorder of unknown aetiology affecting thousands of individuals mostly confined to Eastern sub-Saharan Africa. Previous studies have identified multiple associations-including , antileiomodin-1 antibodies, vitamin B deficiency and measles virus infection-yet, none is proven causal. We conducted a case-control study of children with early-stage nodding syndrome (symptom onset <1 year). Cases and controls were identified through a household survey in the Greater Mundri area in South Sudan. A wide range of parasitic, bacterial, viral, immune-mediated, metabolic and nutritional risk factors was investigated using conventional and state-of-the-art untargeted assays. Associations were examined by multiple logistic regression analysis, and a hypothetical causal model was constructed using structural equation modelling. Of 607 children with nodding syndrome, 72 with early-stage disease were included as cases and matched to 65 household- and 44 community controls. infection (odds ratio 7.04, 95% confidence interval 2.28-21.7), infection (odds ratio 2.33, 95% confidence interval 1.02-5.3), higher antimalarial seroreactivity (odds ratio 1.75, 95% confidence interval 1.20-2.57), higher vitamin E concentration (odds ratio 1.53 per standard deviation increase, 95% confidence interval 1.07-2.19) and lower vitamin B concentration (odds ratio 0.56 per standard deviation increase, 95% confidence interval 0.36-0.87) were associated with higher odds of nodding syndrome. In a structural equation model, we hypothesized that infection, higher vitamin E concentration and fewer viral exposures increased the risk of nodding syndrome while lower vitamin B concentration, and malaria infections resulted from having nodding syndrome. We found no evidence that antileiomodin-1 antibodies, vitamin B and other factors were associated with nodding syndrome. Our results argue against several previous causal hypotheses including . Instead, nodding syndrome may be caused by a complex interplay between multiple pathogens and nutrient levels. Further studies need to confirm these associations and determine the direction of effect.
PubMed: 37731906
DOI: 10.1093/braincomms/fcad223 -
sp. and associated endosymbionts in ring-tailed coatis () in periurban areas from Midwestern Brazil.International Journal For Parasitology.... Dec 2023Coatis () are wild carnivorous well adapted to anthropized environments especially important because they act as reservoirs hosts for many arthropod-borne zoonotic...
Coatis () are wild carnivorous well adapted to anthropized environments especially important because they act as reservoirs hosts for many arthropod-borne zoonotic pathogens. Information about filarioids from coatis and associated spp. in Brazil is scant. To investigate the diversity of filarial nematodes, blood samples (n = 100 animals) were obtained from two urban areas in midwestern Brazil and analyzed using blood smears and buffy coats and cPCR assays based on the 1, 12S rRNA, 18S rRNA, 70 and HC genes for nematodes and 16S rRNA for . When analyzing coati blood smears and buffy coats, 30% and 80% of the samples presented at least one microfilaria, respectively. Twenty-five 1 sequences were obtained showing 89% nucleotide identity with . Phylogenetic analyses clustered 1 sequences herein obtained within the spp. clade. Sequences of both HC and two 70 genes showed 99.8% nucleotide identity with sp. and clustered into a clade within sp., previously detected in coatis from Brazil. Two blood samples were positive for , with a 99% nucleotide identity with previously found in and and in ectoparasites of the genus and . The study showed a high prevalence of sp. in the coati population examined, suggesting that this animal species play a role as reservoirs of a novel, yet to be described, species within the Onchocercidae family.
PubMed: 37584011
DOI: 10.1016/j.ijppaw.2023.08.002 -
PLoS Neglected Tropical Diseases Jun 2023Nodding syndrome (NS) has been consistently associated with onchocerciasis. Nevertheless, a positive association between NS and a Mansonella perstans infection was found...
BACKGROUND
Nodding syndrome (NS) has been consistently associated with onchocerciasis. Nevertheless, a positive association between NS and a Mansonella perstans infection was found in South Sudan. We aimed to determine whether the latter parasite could be a risk factor for NS in Mahenge.
METHODS
Cases of epilepsy were identified in villages affected by NS in Mahenge, Tanzania, and matched with controls without epilepsy of the same sex, age and village. We examined blood films of cases and controls to identify M. perstans infections. The participants were also asked for sociodemographic and epilepsy information, examined for palpable onchocercal nodules and onchocerciasis-related skin lesions and tested for anti-Onchocerca volvulus antibodies (Ov16 IgG4) by ELISA. Clinical characteristics of cases and controls, O. volvulus exposure status and relevant sociodemographic variables were assessed by a conditional logistic regression model for NS and epilepsy status matched for age, sex and village.
RESULTS
A total of 113 epilepsy cases and 132 controls were enrolled, of which, respectively, 56 (49.6%) and 64 (48.5%) were men. The median age in cases and controls was 28.0 (IQR: 22.0-35.0) and 27.0 (IQR: 21.0-33.3) years. Of the persons with epilepsy, 43 (38.1%) met the probable NS criteria and 106 (93.8%) had onchocerciasis-associated epilepsy (OAE). M. perstans infection was absent in all participants, while Ov16 seroprevalence was positively associated with probable NS (odds ratio (OR): 5.05, 95%CI: 1.79-14.27) and overall epilepsy (OR: 2.03, 95%CI: 1-07-3.86). Moreover, onchocerciasis-related skin manifestations were only found in the cases (n = 7, p = 0.0040), including persons with probable NS (n = 4, p = 0.0033). Residing longer in the village and having a family history of seizures were positively correlated with Ov16 status and made persons at higher odds for epilepsy, including probable NS.
CONCLUSION
In contrast to O. volvulus, M. perstans is most likely not endemic to Mahenge and, therefore, cannot be a co-factor for NS in the area. Hence, this filaria is unlikely to be the primary and sole causal factor in the development of NS. The main risk factor for NS remains onchocerciasis.
Topics: Male; Animals; Humans; Young Adult; Adult; Female; Onchocerca volvulus; Onchocerciasis; Mansonella; Tanzania; Case-Control Studies; Nodding Syndrome; Intestinal Volvulus; Seroepidemiologic Studies; Epilepsy; Risk Factors
PubMed: 37339148
DOI: 10.1371/journal.pntd.0011434 -
Brain Communications 2023Nodding syndrome is a paediatric epileptic encephalopathy of unknown aetiology that affects children in impoverished communities of Eastern Africa subject to internal...
Nodding syndrome is a paediatric epileptic encephalopathy of unknown aetiology that affects children in impoverished communities of Eastern Africa subject to internal displacement. Set in southcentral South Sudan, where nodding syndrome first surfaced circa 1990, an important new study of recent-onset cases of nodding syndrome examined parasitic, bacterial, viral, immune-mediated, metabolic and nutritional factors associated with the brain disease. Infection with the nematode , but not with , was the most prominent finding in nodding syndrome cases versus controls. While is unlikely to be causal of nodding syndrome, investigation of the freshwater habitats, where insect-to-human transmission of the filarial larvae takes place, may reveal a clue as to the aetiology of this neurodegenerative disease. The culpable environmental agent(s) must be able to induce neuroinflammation and tau pathology preferentially in infants and children.
PubMed: 37731902
DOI: 10.1093/braincomms/fcad236 -
Frontiers in Tropical Diseases Apr 2024Mouse models of human filarial infections are not only urgently needed to investigate the biology of the nematodes and their modulation of the host's immunity, but will...
INTRODUCTION
Mouse models of human filarial infections are not only urgently needed to investigate the biology of the nematodes and their modulation of the host's immunity, but will also provide a platform to screen and test novel anti-filarial drugs. Recently, murine infection models have been stablished using immunocompromised mouse strains, whereas murine infections have not been implemented until now.
METHODS
Therefore, we aim to establish experimental infections using the immunocompromised mouse strains RAG2IL-2Rγ (lack B, T and natural killer cells), IL-4Rα/IL-5 (impaired IL-4/5 signalling and eosinophil activation) and NOD.Cg-PrkdcIl2rg l/SzJ (NOD scid gamma, NSG) BALB/c mice (lack mature lymphocytes) through subcutaneous (s.c.) or intraperitoneal (i.p.) inoculation of infective stage 3 larvae (L3) isolated from engorged vectors.
RESULTS
In total, 145 immunocompromised mice have been inoculated with 3,250 , 3,337 , and 2,720 L3 to comparatively analyse which immunocompromised mouse strain is susceptible to human filarial infections. Whereas, no and L3 could be recovered upon 2-63 days post-inoculation, a 62-66% L3 recovery rate could be achieved in the different mouse strains. Gender of mice, type of inoculation (s.c. or i.p.) or time point of analysis (2-63 days post inoculation) did not interfere with the success of L3 recovery. In addition, administration of the immune suppressants hydrocortisone, prednisolone and cyclophosphamide did not restore L3 recovery rates.
DISCUSSION
These findings show that RAG2IL-2RgBALB/c and C57BL/6, IL-4Rα/IL-5 BALB/c and NSG mice were not susceptible to and L3 inoculation using the applied methods, whereas infection could be maintained. Further studies should investigate if humanized immunocompromised mice might be susceptible to . and .
PubMed: 38655273
DOI: 10.3389/fitd.2024.1293632 -
Current Research in Parasitology &... 2024Following the successful eradication of , there are now just three species of conventional microfilaremic human filarial parasites endemic to the Brazilian Amazon... (Review)
Review
Following the successful eradication of , there are now just three species of conventional microfilaremic human filarial parasites endemic to the Brazilian Amazon region: , and The zoonotic filarial parasite is also found in the Amazon region as are several sylvatic filarial parasites, some of which have been recorded causing zoonoses and some of which have never been recorded outside the region. is only found in the Amazonia onchocerciasis focus in the Brazilian state of Roraima where it affects the people of the Yanomami tribe living around the densely forested Venezuela border region. is by far the most common filarial parasite in Brazil and has a broad but patchy distribution throughout the western Amazon region. Recorded in the Brazilian states of Acre, Roraima, Matto Grosso, and within almost every municipality of Amazonas state, it is believed that pollution of the urban stream and river systems prevents the development of the simuliid vectors of and explains the parasite's reduced distribution within urban areas and an absence of recent reports from the state capital Manaus. Decades of WHO-led periodic ivermectin treatment of Yanomami tribe's people have resulted in the partial suppression of transmission in this focus and has also probably affected the transmission of in the region. , and very probably infections can all be treated and most likely cured with a 4-6-week treatment course of doxycycline. The Brazilian Ministry of Health does not, however, presently recommend any treatment for mansonellosis infections and thus parasitic infections outside the Amazonia focus are typically left untreated. While the long treatment courses required for doxycycline-based mansonellosis therapies preclude their use in control programmes, new fast-acting filarial drug treatments are likely to soon become available for the treatment of both onchocerciasis and mansonellosis in the Amazon region. Filarial disease management in the Brazilian Amazon is thus likely to become dramatically more viable at a time when the public health importance of these diseases is increasingly being recognized.
PubMed: 38283060
DOI: 10.1016/j.crpvbd.2023.100168 -
PLoS Neglected Tropical Diseases Apr 2024Filariasis, a neglected tropical disease caused by roundworms, is a significant public health concern in many tropical countries. Microscopic examination of blood...
Filariasis, a neglected tropical disease caused by roundworms, is a significant public health concern in many tropical countries. Microscopic examination of blood samples can detect and differentiate parasite species, but it is time consuming and requires expert microscopists, a resource that is not always available. In this context, artificial intelligence (AI) can assist in the diagnosis of this disease by automatically detecting and differentiating microfilariae. In line with the target product profile for lymphatic filariasis as defined by the World Health Organization, we developed an edge AI system running on a smartphone whose camera is aligned with the ocular of an optical microscope that detects and differentiates filarias species in real time without the internet connection. Our object detection algorithm that uses the Single-Shot Detection (SSD) MobileNet V2 detection model was developed with 115 cases, 85 cases with 1903 fields of view and 3342 labels for model training, and 30 cases with 484 fields of view and 873 labels for model validation before clinical validation, is able to detect microfilariae at 10x magnification and distinguishes four species of them at 40x magnification: Loa loa, Mansonella perstans, Wuchereria bancrofti, and Brugia malayi. We validated our augmented microscopy system in the clinical environment by replicating the diagnostic workflow encompassed examinations at 10x and 40x with the assistance of the AI models analyzing 18 samples with the AI running on a middle range smartphone. It achieved an overall precision of 94.14%, recall of 91.90% and F1 score of 93.01% for the screening algorithm and 95.46%, 97.81% and 96.62% for the species differentiation algorithm respectively. This innovative solution has the potential to support filariasis diagnosis and monitoring, particularly in resource-limited settings where access to expert technicians and laboratory equipment is scarce.
Topics: Artificial Intelligence; Microscopy; Humans; Animals; Filariasis; Microfilariae; Algorithms; Smartphone; Elephantiasis, Filarial
PubMed: 38630833
DOI: 10.1371/journal.pntd.0012117