scholarly journals An entomological study of onchocerciasis vectors, Simulium damnosum s.l., in Kinshasa, Democratic Republic of Congo

2021 ◽  
Author(s):  
Jean-Claude MAKENGA BOF ◽  
Paul MANSIANGI ◽  
Josué ZANGA ◽  
Félicien ILUNGA ◽  
Yves COPPIETERS
Keyword(s):  
Aquatic Plants ◽  
Democratic Republic Of Congo ◽  
Abundant Species ◽  
Host Population ◽  
Black Flies ◽  
River Blindness ◽  
Transmission Potential ◽  
Simulium Damnosum ◽  
Plastic Bags ◽  
Biting Rate

Abstract Background Onchocerciasis, a parasitic disease caused by the filarial worm Onchocerca volvulus transmitted through the bite of Simulium (black flies), is a cause of global concern, with the African population being majorly affected. This study focused on the bite rates, bite cycle, and transmission potential of Simulium damnosum s.l. in two sites with river blindness outbreaks in Kinshasa, DRC: Gombe (S1) and Mont-Ngafula at Kimwenza (S2). Methods From August 1, 2019, to July 31, 2020, we captured adult female black flies near breeding sites along the Congo River at S1 and Lukaya Valley at S2. Collections using human baits at the two sites were conducted for five days/month. Results A total of 6082 black flies of species Simulium squamosum (classified based on other entomological surveys) were captured during the study period. The daily cycle of aggression revealed two peaks: one between 8 and 9 a.m. and the other between 4 and 5 p.m. Low bite rates were observed between 11 a.m. and 1 p.m. The annual biting rate/person reached 13,463 in S1 and 23,638 in S2, with a total of 37,101 bites/person. The average daily biting rate, 37 ± 10 and 69 ± 23 bites/day/person in S1 and S2, respectively, did not differ significantly (P = 0.8901). The high density of the host population can disrupt the transmission of vector-borne diseases by diluting the transmission indices. There was no evidence of onchocerciasis transmission at the study sites because of inadequate laboratory facilities in the DRC. Various larval supports have been identified: at Gombe: aquatic plants, plastic bags, dead leaves, and rocks; at Kimwenza: Ledermaniella ledermanii (the most abundant species at the site), plastic bags, artificial waste, and aquatic plants. Conclusions The study provides further evidence for the need for alternative strategies to eliminate the parasite in the formerly hyper-endemic foci.

scholarly journals Seasonality, parity rates and transmission indices of Mansonella ozzardi (Manson) (Nematoda: Onchocercidae) by Cerqueirellum argentiscutum (Shelley & Luna Dias) (Diptera: Simulidae) in a lower Solimões River community, Amazonas, Brazil

2004 ◽  
Vol 34 (2) ◽  
pp. 201-207 ◽  
Author(s):  
Jansen Fernandes de Medeiros ◽  
Victor Py-Daniel
Keyword(s):  
Infection Rate ◽  
Rainy Season ◽  
Parasitic Infection ◽  
Black Flies ◽  
Transmission Potential ◽  
Biting Rate ◽  
Solimões River

Mansonella ozzardi is transmitted by two dipterian families, Ceratopogonidae (midges) and Simuliidae (black flies). In Brazil, black flies are vectors for this filariasis until now. In this paper, we determined the seasonality, parity capacity and parasitic infection rate of Cerqueirellum argentiscutum. The work was carried out in the Porto Japão community, Lower Solimões River, Amazonas, Brazil. Results show that the black flies were more abundant during the rainy season (from December to May). The number of parous flies was higher in every sampling during the course of year. Monthly Biting Rate (MBR1 123742.00, MBR2 86701.50) was high, although Parasitic Infection Rate (PIR1 0.06, PIR2 0.08) and Annual Transmission Potential (ATP 7.25) were low in numbers.

scholarly journals Biting behaviour of Simulium damnosum complex with Onchocerca parasite in Alabameta, Osun State, Southwestern, Nigeria.

2020 ◽  
Author(s):  
Lateef O Busari ◽  
Olusola O Ojurongbe ◽  
Monsuru A Adeleke ◽  
Olabanji A Surakat
Keyword(s):  
Significant Variation ◽  
Seasonal Abundance ◽  
World Health ◽  
Forest Species ◽  
Southwestern Nigeria ◽  
Transmission Potential ◽  
Simulium Damnosum ◽  
Biting Rate ◽  
Health Organization ◽  
Biting Behaviour

Background and Objectives: A longitudinal study was carried out to investigate species composition, seasonal abundance, parity and transmission potential of Simulium damnosum complex in Alabameta community in Osogbo, Southwestern, Nigeria. Methods: Adult Simulium damnosum complex were collected along Owena River, Alabameta, by two dark complexioned vector collectors from 07:00hr to 18:00hr weekly using collecting tubes from November 2014 to April 2015. The flies were morphologically identified and dissected for the purpose of detecting Onchocerca parasite using dissecting microscope. The Monthly Biting Rate (MBR) of flies was determined using World Health Organization standard formula. Results: A total of four hundred and forty flies were collected during the study period with all of them identified as forest species of Simulium damnosum complex. There was significant variation in monthly collection of the flies with the month of November having the highest number of flies (194) (44%) while the month of April recorded the lowest number of flies (31) (7%) (p<0.05). The morning biting peak (09hr - 11hr) (137) was higher than the evening biting peak (15hr -17hr) (64) (p<0.05) while nulliparous flies (294) (67%) were more abundant than the parous flies (146) (33%) (p<0.05). There was absence of infection (zero infectivity) of the flies (p<0.05). Conclusion: The zero infectivity in the flies indicates zero transmission of Onchocerca parasite in the community which if sustained over a period of time may signify the possibility of onchocerciasis elimination. Also, the presence of forest species of the flies reduces the risk of residents exposure to blindness since the savannah species of the flies are responsible for this.

scholarly journals Biting behaviour and infectivity of Simulium damnosum complex with Onchocerca parasite in Alabameta, Osun State, Southwestern, Nigeria

PLoS ONE ◽  
2021 ◽  
Vol 16 (6) ◽  
pp. e0252652
Author(s):  
Lateef O. Busari ◽  
Olusola Ojurongbe ◽  
Monsuru A. Adeleke ◽  
Olabanji A. Surakat ◽  
Akeem A. Akindele
Keyword(s):  
Significant Variation ◽  
Seasonal Abundance ◽  
World Health ◽  
Forest Species ◽  
Southwestern Nigeria ◽  
Transmission Potential ◽  
Simulium Damnosum ◽  
Biting Rate ◽  
Health Organization ◽  
Biting Behaviour

A longitudinal study was carried out to investigate species composition, seasonal abundance, parity and transmission potential of Simulium damnosum complex in Alabameta community in Osun State, Southwestern, Nigeria. Adult Simulium damnosum complex were collected along Owena River, Alabameta, by two dark complexioned vector collectors from 07:00hr to 18:00hr weekly using collecting tubes from November 2014 to April 2015. The flies were morphologically identified and dissected for the purpose of detecting Onchocerca parasite using dissecting microscope. The Monthly Biting Rate (MBR) of flies was determined using World Health Organization standard formula. A total of four hundred and forty flies were collected during the study period with all of them identified as forest species of Simulium damnosum complex. There was significant variation in monthly collection of the flies with the month of November having the highest number of flies (194) (44%) while the month of April recorded the lowest number of flies (31) (7%) (p<0.05). The morning biting peak (09hr - 11hr) (137) was higher than the evening biting peak (15hr -17hr) (64) (p<0.05) while nulliparous flies (294) (67%) were more abundant than the parous flies (146) (33%) (p<0.05). There was absence of infection (zero infectivity) of the flies (p<0.05). The zero infectivity in the flies may plausibly indicate the possibility of zero transmission of Onchocerca parasite in the community which if sustained over a period of time may signify the possibility of onchocerciasis elimination. Also, the presence of forest species of the flies reduces the risk of resident’s intense exposure to blinding savannah strain of onchocerciasis.

ECOLOGY OF BLACK FLIES (DIPTERA: SIMULIIDAE) OF THE SOURIS RIVER, MANITOBA AS A BASIS FOR CONTROL STRATEGY

1981 ◽  
Vol 113 (3) ◽  
pp. 223-234 ◽  
Author(s):  
A. R. Westwood ◽  
R. A. Brust
Keyword(s):  
Control Program ◽  
Abundant Species ◽  
Pest Species ◽  
Black Flies ◽  
Black Fly ◽  
Simulium Vittatum ◽  
Late Instar ◽  
Simulium Decorum ◽  
Fly Control ◽  
Wire Cage

AbstractTen species of black flies were collected from the Souris River, Manitoba between April 1977 and October 1978. Adults of Simulium luggeri Nicholson and Mickel, Simulium meridionale Riley, Simulium venustum Say, Simulium verecundum Stone and Jamnback, and Simulium johannseni johannseni (Hart) were collected feeding on livestock and humans, and are well known pest species. Simulium vittatum Zetterstedt was the most abundant species, but was not a pest on man or domestic animals. Simulium tuberosum (Lundström) and Simulium johannseni duplex Shewell and Fredeen were the least abundant species. Simulium j. johannseni, S. j. duplex, S. venustum, S. verecundum, S. tuberosum, and Cnephia dacotensis (Dyar and Shannon) appeared to be univoltine species while S. luggeri, S. meridionale, Simulium decorum Walker, and S. vittatum were multivoltine in the Souris River.An evaluation of cone, plate, rope, and wire cage sampling devices for black fly larvae and pupae indicated that cone samplers provided a more representative sample for population assessment.In a black fly control program, of the Souris River, Manitoba two separate larvicide treatments in spring may be necessary. In the case of two treatments, the first should be aimed at late instar larvae of S. j. johannseni, S. venustum, and S. verecundum. Since the majority of S. luggeri and S. meridionale would be in the egg stage at this time, a second treatment, 10–14 days later, would be necessary to control late instar larvae of these species.

Environmental variability and the transmission of haemorrhagic fever with renal syndrome in Changsha, People's Republic of China

2012 ◽  
Vol 141 (9) ◽  
pp. 1867-1875 ◽  
Author(s):  
H. XIAO ◽  
L. D. GAO ◽  
X. J. LI ◽  
X. L. LIN ◽  
X. Y. DAI ◽  
...  
Keyword(s):  
Disease Surveillance ◽  
Environmental Variability ◽  
Southern Oscillation ◽  
Host Population ◽  
Haemorrhagic Fever ◽  
Rodent Host ◽  
Transmission Potential ◽  
Republic Of China ◽  
Disease Occurrence ◽  
Disease Epidemics

SUMMARYThe transmission of haemorrhagic fever with renal syndrome (HFRS) is influenced by climatic, reservoir and environmental variables. The epidemiology of the disease was studied over a 6-year period in Changsha. Variables relating to climate, environment, rodent host distribution and disease occurrence were collected monthly and analysed using a time-series adjusted Poisson regression model. It was found that the density of the rodent host and multivariate El Niño Southern Oscillation index had the greatest effect on the transmission of HFRS with lags of 2–6 months. However, a number of climatic and environmental factors played important roles in affecting the density and transmission potential of the rodent host population. It was concluded that the measurement of a number of these variables could be used in disease surveillance to give useful advance warning of potential disease epidemics.

Observations on the biology of Mansonia perturbans (Walker) (Diptera: Culicidae) in the Nova Scotia–New Brunswick border region

1980 ◽  
Vol 58 (11) ◽  
pp. 2084-2088 ◽  
Author(s):  
David J. Lewis ◽  
Gordon F. Bennett
Keyword(s):  
Nova Scotia ◽  
New Brunswick ◽  
Aquatic Plants ◽  
Adult Emergence ◽  
Abundant Species ◽  
Border Region ◽  
Immature Stages ◽  
Peak Activity ◽  
Peak Abundance

Aerial sweep netting of mosquitoes in the Nova Scotia – New Brunswick border region during the summers of 1973–1975 revealed that Mansonia perturbons (Walker) is the most abundant species in this region. This mosquito is univoltine; adult emergence commences in late June; peak abundance occurs about mid-July; peak activity of blood-seeking females occurs at or near darkness. Observations were made of swarming adults, and the immature stages were associated with at least seven species of aquatic plants. Mansonia perturbans appears to have become a relatively recent pest in this region.

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

scholarly journals Spatio-temporal distribution of preimaginal black flies (Diptera: Simuliidae) in streams of a sub-basin of the Uruguay river basin, southern Brazil

2021 ◽  
Vol 14 ◽  
pp. e946
Author(s):  
Patricia Maria Limberger ◽  
David Augusto Reynalte Tataje ◽  
Darlan Novicki ◽  
Luiz Carlos Marmilicz Junior ◽  
Milton Norberto Strieder
Keyword(s):  
Abiotic Factors ◽  
Temporal Distribution ◽  
Canopy Cover ◽  
Abundant Species ◽  
Immature Stages ◽  
Black Flies ◽  
Southern Brazil ◽  
Spatial And Temporal Scales ◽  
Conditioning Factors ◽  
Blood Sucking

Adult females of most black flies species (Diptera, Simuliidae) exhibit a blood-sucking habit. Immature stages develop in water courses and are important in the ecology of lotic environments. We aim to understand the distribution of immature simuliids in the hydrographic sub-basin of the Comandaí river, in Northwest of Rio Grande do Sul, Brazil. For that purpose, simuliids were sampled in three stretches (source, intermediate and mouth) of nine streams, distributed along the three main regions of the sub-basin. Evaluations of the influence of abiotic factors in different spatial and temporal scales were made. Sampling was carried out in two seasons: between September and November 2016 (spring), and between April and July 2017 (autumn). In total, 17,146 individuals were sampled (larvae of last instars and pupae), which resulted in the identification of eleven Simuliidae species. The most abundant species were Simulium pertinax Kollar (77.55%), followed by Simulium incrustatum Lutz (14.56%) and Simulium subpallidum Lutz (2.35%). Regarding the identification of indicator species, S. pertinax, Simulium jujuyense Paterson & Shannon, S. subpallidum and Simulium orbitale Lutz stood out in mouth stretches, and Simulium rubrithorax Lutz in source stretches. Environmental variables such as conductivity, altitude, canopy cover and stream width were interpreted as important conditioning factors for the distribution of simuliid immature stages. In general, we concluded that Simuliidae are more abundant during spring in the study area, mainly downstream. This information may contribute to the implementation of efficient measures to control species of health importance in southern Brazil.  

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

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