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The American Journal of Tropical... Sep 2017Multiplex bead assays (MBAs) may provide a powerful integrated tool for monitoring, evaluation, and post-elimination surveillance of onchocerciasis and co-endemic...
Multiplex bead assays (MBAs) may provide a powerful integrated tool for monitoring, evaluation, and post-elimination surveillance of onchocerciasis and co-endemic diseases; however, the specificity and sensitivity of antigens have not been characterized within this context. An MBA was developed to evaluate three antigens (OV-16, OV-17, and OV-33) for onchocerciasis. Receiver operating characteristics (ROC) analyses were used to characterize antigen performance using a panel of 610 specimens: 109 -positive specimens, 426 non-onchocerciasis controls with filarial and other confirmed parasitic infection, and 75 sera from patients with no other parasitic infection. The IgG and IgG4 assays for OV-16 demonstrated sensitivities of 95.4% and 96.3%, and specificities of 99.4% and 99.8%, respectively. The OV-17 IgG and IgG4 assays had sensitivities of 86.2% and 76.1% and specificities of 79.2% and 82.8%. For OV-33, the IgG and IgG4 assays had sensitivities of 90.8% and 96.3%, and specificities of 96.8% and 98.6%. The OV-16 IgG4-based MBA had the best assay characteristics, followed by OV-33 IgG4. The OV-16 IgG4 assay would be useful for monitoring and evaluation using the MBA platform. Further evaluations are needed to review the potential use of OV-33 as a confirmatory test in the context of program evaluations.
Topics: Animals; Antibodies, Helminth; Antigens, Helminth; False Positive Reactions; Humans; Immunoassay; Immunoglobulin G; Onchocerca volvulus; Onchocerciasis; Sensitivity and Specificity
PubMed: 28722605
DOI: 10.4269/ajtmh.16-0519 -
Frontiers in Cellular and Infection... 2022Human onchocerciasis is a devastating neglected tropical disease caused by infection of the filarial nematode . The infection can cause irreversible visual impairment or... (Review)
Review
Human onchocerciasis is a devastating neglected tropical disease caused by infection of the filarial nematode . The infection can cause irreversible visual impairment or blindness and stigmatizing dermatitis. More than 32 million people were estimated to be infected with in Africa, and 385,000 suffered from blindness. Even though the implementation of mass drug administration (MDA) with ivermectin has reduced the global prevalence of onchocerciasis, infection remains challenging to control because MDA with ivermectin cannot be implemented in endemic areas co-endemic with loiasis due to the risk of severe adverse events. There is also emerging drug resistance to ivermectin that further complicates the elimination of onchocerciasis. Thus, the development of a vaccine that would induce protective immunity and reduce infection burden is essential. Efforts to develop prophylactic and/or therapeutic vaccines for onchocerciasis have been explored since the late 1980s by many researchers and entities, and here we summarize the recent advances made in the development of vaccines against the infection of and onchocerciasis.
Topics: Animals; Blindness; Cattle; Humans; Intestinal Volvulus; Ivermectin; Onchocerca; Onchocerciasis; Vaccines
PubMed: 35444961
DOI: 10.3389/fcimb.2022.869039 -
The American Journal of Tropical... Oct 2018Yemen is a country that has been treating severe cases of oncho-dermatitis since 1992 and is now moving to a program aimed at the elimination of the transmission of . It...
Yemen is a country that has been treating severe cases of oncho-dermatitis since 1992 and is now moving to a program aimed at the elimination of the transmission of . It is important to ensure that the currently acceptable tools used in epidemiological assessment of onchocerciasis in Africa and Latin America also apply to Yemen. Five hundred and ten blood samples from three known -endemic areas, locations that have never been under a mass treatment program, were tested for the presence of antibodies against a panel of -specific antigens using enzyme-linked immunosorbent assay (Ov16) and luciferase immunoprecipitation system (Ov-FAR-1 and Ov-MSA-1) assays. Overall, 31.4% of the samples tested were positive, with positivity increasing with age. Positivity was seen in 76.5% of those presenting with clinical onchocerciasis but importantly also in more than 28.5% of those defined as free of oncho-dermatitis; these latter individuals are likely to be serving as a source for persistent reinfection. This study supports the use of the current -specific serologic methodology in Yemen.
Topics: Adolescent; Adult; Animals; Antibodies, Helminth; Antigens, Helminth; Child; Enzyme-Linked Immunosorbent Assay; Epidemiological Monitoring; Female; Humans; Immunoprecipitation; Male; Middle Aged; Onchocerca volvulus; Onchocerciasis; Prevalence; Surveys and Questionnaires; Yemen
PubMed: 30084341
DOI: 10.4269/ajtmh.18-0051 -
PloS One 2017Few studies have documented the interruption of onchocerciasis and Lymphatic Filariasis (LF) by integrated chemotherapy in Uganda. The study describes the interruption...
INTERVENTION
Few studies have documented the interruption of onchocerciasis and Lymphatic Filariasis (LF) by integrated chemotherapy in Uganda. The study describes the interruption of transmission of the two diseases co-endemic in Obongi focus, north western Uganda. Base line data for Onchocerciasis and LF were collected in 1994 and 2006, respectively. Annual mass drug administration for onchocerciasis (Ivermectin) and Lymphatic Filariasis (Ivermectin + albendazole) was conducted for 20 and 6 years, respectively. Thereafter, assessments by skin snip, larval searches in rivers and human landing catches were performed. Children <10 years were screened for IgG4 antibodies using Ov16 ELISA technique in 2013. LF Pre-TAS and TAS1 were conducted in sentinel sites. ITN coverage and utilization for the implementation unit was also reported.
INTERVENTION COVERAGE
Onchocerciasis treatment coverage was <80% but improved with the introduction of CDTI in 1999. While for LF, effective coverage of >65% was achieved in the six treatment rounds. Household ownership of ITN's and utilization was 96% and 72.4%., respectively.
IMPACT
Parasitological examinations conducted for onchocerciasis among 807 adults and children, revealed a reduction in mf prevalence from 58% in 1994 to 0% in 2012. Entomological monitoring conducted at the two sites had no single Simulium damnosum fly caught. Serological analysis using Ov16 ELISA for onchocerciasis revealed that out of the 3,308 children <10 years old screened in 2013, only 3/3308 (0.091%) positive cases were detected. All Ov16 positive children were negative when tested for patent infection by skin snip PCR. A reduction in LF microfilaria prevalence from 2.5% (n = 13/522) in 2006 to 0.0% (n = 602) in 2014 was observed. LF TAS1 conducted in 2015 among 1,532 children 6-7 years, all were negative for antigens of W. bancrofti.
CONCLUSION
The results concluded that interruption of onchocerciasis and LF has been achieved.
Topics: Adolescent; Albendazole; Animals; Antiparasitic Agents; Child; Child, Preschool; Elephantiasis, Filarial; Enzyme-Linked Immunosorbent Assay; Female; Humans; Immunoglobulin G; Ivermectin; Male; Onchocerca volvulus; Onchocerciasis; Prevalence; Uganda; Wuchereria bancrofti
PubMed: 29253862
DOI: 10.1371/journal.pone.0189306 -
International Journal of Infectious... Feb 2020Epidemiological evidence links onchocerciasis with the development of epilepsy. The aim of this study was to detect Onchocerca volvulus microfilariae or its bacterial...
OBJECTIVES
Epidemiological evidence links onchocerciasis with the development of epilepsy. The aim of this study was to detect Onchocerca volvulus microfilariae or its bacterial endosymbiont, Wolbachia, in the cerebrospinal fluid (CSF) of persons with onchocerciasis-associated epilepsy (OAE).
METHODS
Thirteen persons with OAE and O. volvulus skin snip densities of >80 microfilariae were recruited in Maridi County (South Sudan) and their CSF obtained. Cytospin centrifuged preparations of CSF were examined by light microscopy for the presence of O. volvulus microfilariae. DNA was extracted from CSF to detect O. volvulus (O-150 repeat) by quantitative real-time PCR, and Wolbachia (FtsZ gene) by standard PCR. To further investigate whether CSF from onchocerciasis-infected participants could induce seizures, 3- and 7-day old zebrafish larvae were injected with the CSF intracardially and intraperitoneally, respectively. For other zebrafish larvae, CSF was added directly to the larval medium.
RESULTS
No microfilariae, parasite DNA, or Wolbachia DNA were detected in any of the CSF samples by light microscopy or PCR. All zebrafish survived the procedures and none developed seizures.
CONCLUSIONS
The absence of O. volvulus in the CSF suggests that OAE is likely not caused by direct parasite invasion into the central nervous system, but by another phenomenon triggered by O. volvulus infection.
Topics: Adult; Animals; DNA, Helminth; Epilepsy; Female; Humans; Male; Microfilariae; Onchocerca volvulus; Onchocerciasis; Real-Time Polymerase Chain Reaction; Skin; Zebrafish
PubMed: 31786246
DOI: 10.1016/j.ijid.2019.11.029 -
Cadernos de Saude Publica 2002Human onchocerciasis was recently discovered in Brazil among Yanomámi Indians living along the border region with Venezuela in the States of Amazonas and Roraima. The... (Review)
Review
Human onchocerciasis was recently discovered in Brazil among Yanomámi Indians living along the border region with Venezuela in the States of Amazonas and Roraima. The article reports on the history of the disease's discovery, its distribution, and incrimination of vector simuliid species. The literature that has been generated on the parasite, its vectors, and control of the disease is critically analyzed as well as the organization of epidemiological surveys and the control program developed by the Brazilian government and an international agency. Suggestions for future work are made.
Topics: Animals; Brazil; Disease Vectors; Humans; Indians, South American; Onchocerca; Onchocerca volvulus; Onchocerciasis; Simuliidae
PubMed: 12244349
DOI: 10.1590/s0102-311x2002000500009 -
Tropical Medicine & International... Jul 2006Bioko is the only island known in the world with endemic onchocerciasis. The island's rural communities consist of villages and cocoa plantations inhabited by Bubi and...
Reduction in the prevalence and intensity of infection in Onchocerca volvulus microfilariae according to ethnicity and community after 8 years of ivermectin treatment on the island of Bioko, Equatorial Guinea.
Bioko is the only island known in the world with endemic onchocerciasis. The island's rural communities consist of villages and cocoa plantations inhabited by Bubi and Fang ethnic groups. The aim of this study was to evaluate the impact of 8 years of vertical ivermectin distribution on the prevalence and intensity of Onchocerca volvulus infection in the rural population by means of pre- (1989) and post-long term treatment (1998) epidemiological surveys. In both surveys, the entire population of 12 randomly selected communities (1723 and 1082 individuals) was examined. The mean ivermectin therapeutic coverage for the 8 years was 53.2%. Iliac crest skin snips were used for differential diagnosis between O. volvulus and Mansonella streptocerca. The crude O. volvulus infection prevalence before ivermectin intervention was 74.5% (1284/1723); after the intervention it was 38.4% (415/1082). The Community Microfilarial Load (CMFL) before and after ivermectin intervention was 28.29 microfilariae/snip vs. 2.32 microfilariae/snip. The reduction in prevalence and CMFL after eight annual rounds of ivermectin treatment corroborates the drug microfilaricidal activity and good tolerability. In the pre-treatment survey, the prevalence was higher in the Bubi group (77.1%, 1126/1461); post-treatment it was higher among the Fang (51.1%, 92/180). The reduction in prevalence and intensity of O. volvulus infection differed between ethnic groups and communities.
Topics: Adolescent; Adult; Age Distribution; Aged; Aged, 80 and over; Animals; Anthelmintics; Child; Child, Preschool; Equatorial Guinea; Female; Humans; Infant; Infant, Newborn; Ivermectin; Long-Term Care; Male; Microfilariae; Middle Aged; Onchocerca volvulus; Onchocerciasis; Population Surveillance; Prevalence; Rural Health; Sex Distribution; Skin
PubMed: 16827709
DOI: 10.1111/j.1365-3156.2006.01650.x -
Parasitology Research Nov 2009Drugs exist that show long-lasting inhibition of embryogenesis and microfilaria production or macrofilaricidal activity against Onchocerca volvulus. Therefore, the...
Drugs exist that show long-lasting inhibition of embryogenesis and microfilaria production or macrofilaricidal activity against Onchocerca volvulus. Therefore, the patients have to be followed-up for several years. Clinical drug trials have to be performed in areas with ongoing transmission to assess the efficacy on younger worms. In addition, future vaccine trials may also require demonstrating efficacy against establishment of new worms. For the evaluation of the efficacy, it is necessary to differentiate between older worms, which were exposed to the drug, and younger worms newly acquired after drug treatment or vaccination. Here, we describe criteria for the differentiation between young and old filariae based on histological studies of worms with a known age from travellers, or from children, or patients living in areas with interrupted transmission in Burkina Faso, Ghana or Uganda. Older worms were larger and presented degenerated tissues. Gomori's iron stain showed that the worms accumulated more iron with increasing age, first in the gut and later in other organs. Using an antibody against O. volvulus lysosomal aspartic protease, the gut of young worms was stained only weakly; whereas, it was stronger labelled in older worms, accompanied by additional staining of hypodermis and epithelia. Using morphological and immunohistological criteria, it was possible to differentiate young (1-3 years old) from older females and to identify young males.
Topics: Animals; Aspartic Acid Proteases; Burkina Faso; Child; Child, Preschool; Ghana; Histocytochemistry; Humans; Immunohistochemistry; Iron; Male; Microscopy; Onchocerca volvulus; Staining and Labeling; Uganda
PubMed: 19784672
DOI: 10.1007/s00436-009-1588-5 -
Parasitology Apr 2010Up to 5% of untreated female Onchocerca volvulus filariae develop potentially fatal pleomorphic neoplasms, whose incidence is increased following ivermectin treatment....
Up to 5% of untreated female Onchocerca volvulus filariae develop potentially fatal pleomorphic neoplasms, whose incidence is increased following ivermectin treatment. We studied the occurrence of 8 filarial proteins and of Wolbachia endobacteria in the tumor cells. Onchocercomas from patients, untreated and treated with antibiotics and anthelminthics, were examined by immunohistology. Neoplasms were diagnosed in 112 of 3587 female and in 2 of 1570 male O. volvulus. The following proteins and other compounds of O. volvulus were expressed in the cells of the neoplasms: glutathione S-transferase 1, lysosomal aspartic protease, cAMP-dependent protein kinase, alpha-enolase, aspartate aminotransferase, ankyrin E1, tropomyosin, heat shock protein 60, transforming growth factor-beta, and prostaglandin E(2). These findings prove the filarial origin of the neoplasms and confirm the pleomorphism of the tumor cells. Signs indicating malignancy of the neoplasms are described. Wolbachia were observed in the hypodermis, oocytes, and embryos of tumor-harbouring filariae using antibodies against Wolbachia surface protein, Wolbachia HtrA-type serine protease, and Wolbachia aspartate aminotransferase. In contrast, Wolbachia were not found in the cells of the neoplasms. Further, neoplasm-containing worms were not observed after more than 10 months after the start of sufficient treatment with doxycycline or doxycycline plus ivermectin.
Topics: Africa South of the Sahara; Animals; Doxycycline; Female; Helminth Proteins; Humans; Immunohistochemistry; Male; Neoplasms; Onchocerca volvulus; Onchocerciasis
PubMed: 20199697
DOI: 10.1017/S0031182009992010 -
Parasitology Jun 2006Ivermectin treatment may induce severe adverse reactions in some individuals heavily infected with Loa loa. This hampers the implementation of mass ivermectin treatment... (Comparative Study)
Comparative Study
Ivermectin treatment may induce severe adverse reactions in some individuals heavily infected with Loa loa. This hampers the implementation of mass ivermectin treatment against onchocerciasis in areas where Onchocerca volvulus and L. loa are co-endemic. In order to identify factors, including co-infections, which may explain the presence of high L. loa microfilaraemia in some individuals, we analysed data collected in 19 villages of central Cameroon. Two standardized skin snips and 30 mul of blood were obtained from each of 3190 participants and the microfilarial (mf) loads of both O. volvulus and L. loa were quantified. The data were analysed using multivariate hierarchical models. Individual-level variables were: age, sex, mf presence, and mf load; village-related variables included the endemicity levels for each infection. The two species show a certain degree of ecological separation in the study area. However, for a given individual host, the presence of microfilariae of one species was positively associated with the presence of microfilariae of the other (OR=1.79, 95% CI [1.43-2.24]). Among individuals harbouring Loa microfilariae, there was a slight positive relationship between the L. loa and O. volvulus mf loads which corresponded to an 11% increase in L. loa mf load per 100 O. volvulus microfilariae. Co-infection with O. volvulus is not sufficient to explain the very high L. loa mf loads harboured by some individuals.
Topics: Adolescent; Adult; Age Factors; Animals; Cameroon; Child; Child, Preschool; Endemic Diseases; Female; Humans; Loa; Logistic Models; Loiasis; Male; Middle Aged; Odds Ratio; Onchocerca volvulus; Onchocerciasis; Prevalence; Skin
PubMed: 16469200
DOI: 10.1017/S003118200600984X