scholarly journals Oligonucleotide Based Magnetic Bead Capture of Onchocerca volvulus DNA for PCR Pool Screening of Vector Black Flies

2012 ◽  
Vol 6 (6) ◽  
pp. e1712 ◽  
Author(s):  
Hemavathi Gopal ◽  
Hassan K. Hassan ◽  
Mario A. Rodríguez-Pérez ◽  
Laurent D. Toé ◽  
Sara Lustigman ◽  
...  
Keyword(s):  
Magnetic Bead ◽  
Onchocerca Volvulus ◽  
Black Flies ◽  
Pool Screening

scholarly journals Onchocerca volvulus transmission in the Mbam valley of Cameroon following 16 years of annual community-directed treatment with ivermectin, and the description of a new cytotype of Simulium squamosum

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Adam Hendy ◽  
Meryam Krit ◽  
Kenneth Pfarr ◽  
Christine Laemmer ◽  
Jacobus De Witte ◽  
...  
Keyword(s):  
Dry Season ◽  
Onchocerca Volvulus ◽  
Black Flies ◽  
Infection Rates ◽  
Transmission Rates ◽  
Pool Screening ◽  
Simulium Damnosum ◽  
First Time

Abstract Background The onchocerciasis focus surrounding the lower Mbam and Sanaga rivers, where Onchocerca volvulus is transmitted by Simulium damnosum s.l. (Diptera: Simuliidae), was historically the largest in the southern regions of Cameroon. Annual community-directed treatment with ivermectin (CDTI) has been taking place since 2000, but recent studies have shown that new infections are occurring in children. We aimed to investigate blackfly biting and O. volvulus transmission rates along the lower Mbam river 16 years after the formal onset of annual CDTI. Methods Black flies were collected for three consecutive days each month between July 2016 and June 2017 at two riverside villages and two inland sites situated 4.9 km and 7.9 km from the riverside. Specimens collected at each site were dissected on one of the three collection days each month to estimate parity rates and O. volvulus infection rates, while the remaining samples were preserved for pool screening. Results In total, 93,573 S. damnosum s.l. black flies were recorded biting humans and 9281 were dissected. Annual biting rates of up to 606,370 were estimated at the riverside, decreasing to 20,540 at 7.9 km, while, based on dissections, annual transmission potentials of up to 4488 were estimated at the riverside, decreasing to 102 and 0 at 4.9 km and 7.9 km, respectively. However, pool screening showed evidence of infection in black flies at the furthest distance from the river. Results of both methods demonstrated the percentage of infective flies to be relatively low (0.10–0.36%), but above the WHO threshold for interruption of transmission. In addition, a small number of larvae collected during the dry season revealed the presence of Simulium squamosum E. This is the first time S. squamosum E has been found east of Lake Volta in Ghana, but our material was chromosomally distinctive, and we call it S. squamosum E2. Conclusions Relatively low O. volvulus infection rates appear to be offset by extremely high densities of biting black flies which are sustaining transmission along the banks of the lower Mbam river. Graphical Abstract

Detection of Onchocerca volvulus in Latin American black flies for pool screening PCR using high-throughput automated DNA isolation for transmission surveillance

2013 ◽  
Vol 112 (11) ◽  
pp. 3925-3931 ◽  
Author(s):  
Mario A. Rodríguez-Pérez ◽  
Hemavathi Gopal ◽  
Monsuru Adebayo Adeleke ◽  
Erick Jesús De Luna-Santillana ◽  
J. Natividad Gurrola-Reyes ◽  
...  
Keyword(s):  
Latin American ◽  
High Throughput ◽  
Dna Isolation ◽  
Onchocerca Volvulus ◽  
Black Flies ◽  
Pool Screening ◽  
American Black

scholarly journals Polymerase Chain Reaction Pool Screening Used To Compare Prevalence of Infective Black Flies in Two Onchocerciasis Foci in Northern Sudan

2011 ◽  
Vol 84 (5) ◽  
pp. 753-756 ◽  
Author(s):  
Tarig B. Higazi ◽  
Thomas R. Unnasch ◽  
Hanan A. Mohamed ◽  
Frank Richards ◽  
Nabil Aziz ◽  
...  
Keyword(s):  
Polymerase Chain Reaction ◽  
Black Flies ◽  
Chain Reaction ◽  
Pool Screening ◽  
Polymerase Chain

scholarly journals Beginning of the end of Onchocerciasis in the Americas

2013 ◽  
pp. 132-133
Author(s):  
Gloria Ines Palma ◽  
Sofía Duque Bernal ◽  
Ruben Santiago Nicholls
Keyword(s):  
West Africa ◽  
20Th Century ◽  
Slave Trade ◽  
Onchocerca Volvulus ◽  
Parasitic Disease ◽  
Black Flies ◽  
River Blindness ◽  
Vector Borne ◽  
Single Focus ◽  
Transmission Foci

Onchocerciasis, also known as River Blindness, is a parasitic disease caused by the nematode Onchocerca volvulus and transmitted by black flies of the genus Simulium. It is endemic in Africa, where an estimated 37 million people are infected. It is almost certain that the slave trade in the 17th and 18th centuries brought onchocerciasis from West Africa to the Americas (1), where transmission foci where established in six countries: Mexico, Guatemala, Venezuela, Brazil, Ecuador and Colombia. Since the beginning of the 20th century it was suspected that this vector borne disease was present in Colombia but the first confirmed case was not reported until 1965. The exact location of the single focus in the country was confirmed almost thirty years later in the locality of Naicioná, on the stream that bears the same name

scholarly journals A Simple Isothermal DNA Amplification Method to Screen Black Flies for Onchocerca volvulus Infection

PLoS ONE ◽  
2014 ◽  
Vol 9 (10) ◽  
pp. e108927 ◽  
Author(s):  
Andy Alhassan ◽  
Benjamin L. Makepeace ◽  
Elwyn James LaCourse ◽  
Mike Y. Osei-Atweneboana ◽  
Clotilde K. S. Carlow
Keyword(s):  
Dna Amplification ◽  
Onchocerca Volvulus ◽  
Black Flies ◽  
Amplification Method

Detection of Onchocerca volvulus infection in Simulium ochraceum sensu lato: comparison of a PCR assay and fly dissection in a Mexican hypoendemic community

Parasitology ◽  
1999 ◽  
Vol 119 (6) ◽  
pp. 613-619 ◽  
Author(s):  
M. A. RODRÍGUEZ-PÉREZ ◽  
R. DANIS-LOZANO ◽  
M. H. RODRÍGUEZ ◽  
T. R. UNNASCH ◽  
J. E. BRADLEY
Keyword(s):  
Onchocerca Volvulus ◽  
Entomological Surveillance ◽  
Pcr Assay ◽  
Vector Population ◽  
Pool Screening ◽  
Mexican Community ◽  
Control Programmes ◽  
Local Vector ◽  
Level 1 ◽  
Onchocerciasis Control

Detection of Onchocerca volvulus larvae in vector populations is of prime importance in the assessment of the effectiveness of onchocerciasis control programmes. Traditionally, detection of larvae is attained by the dissection of flies, but this time-consuming method cannot easily discriminate between species of Onchocerca. The genome of all Onchocerca species has a unique 150 bp repeat, which can be amplified by PCR, and O. volvulus-specific DNA probes can detect these products by Southern blot (SB). This study optimizes a PCR/SB assay, and compares it with fly dissection to estimate the prevalence (p) and intensity of infection (m) in the local vector population of a Mexican community that has become hypoendemic as a result of 7 years of treatment with ivermectin and nodulectomy. The PCR detected 1 infected fly in a pool of 99 uninfected flies, but the optimal pool size was 50 flies. At the community level, 1 out of 10550 flies was positive (p=0·0095%, 95% confidence intervals CI=0·00024–07·05280%; m=0·00027 larvae/parous fly, CI=−0·00026–0·00081) by PCR, and 4 out of 10772 flies (p=0·0371%, CI=0·01012–0.09505%; m=0·00107 larvae/parous fly, 95% CI=0·00002–0·00212) by dissection (observed m=0·0005). Both methods produce statistically similar estimates of the prevalence and intensity, indicating that pool screening is a viable alternative for entomological surveillance in areas where the intensity of transmission is becoming extremely low as a result of control interventions.

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