Biting Density

Introduction and objective. The effect of climatic conditions on the biting density and relative abundance of Simulium damnosum complex at Adani, Nigeria, from August 2010-January 2011 was investigated. Materials and methods: The classical method of collecting blackflies for a period of 11 hours using human attractants was employed in the study. Monthly climatic data, such as rainfall, relative humidity and temperature were collected for the period of study. Results. Rainfall, relative humidity, temperature, harmattan (cold, dry wind) and deforestation were observed to affect the biting density and relative abundance of blackflies at the site. A total of 548 female adult blackflies were collected. The biting density of the flies ranged from 0.5 Flies/Man/Hour (FMH) in December to 5.5 FMH in January. The relative abundance of the flies ranged from 21 in December to 243 in January. Regression analysis showed that temperature and relative humidity had a positive correlation with relative abundance of Simulium damnosum complex (y =-0.0006x + 25.593, r = 0.0519) and (y =-0.1213x + 78.794, r = 0.505), respectively. Conclusions. The risk of getting infected with Onchocerca volvulus increased during the dry season with its associated weather conditions.

Introduction and objective. The effect of climatic conditions on the biting density and relative abundance of Simulium damnosum complex at Adani, Nigeria, from August 2010-January 2011 was investigated. Materials and methods: The classical method of collecting blackflies for a period of 11 hours using human attractants was employed in the study. Monthly climatic data, such as rainfall, relative humidity and temperature were collected for the period of study. Results. Rainfall, relative humidity, temperature, harmattan (cold, dry wind) and deforestation were observed to affect the biting density and relative abundance of blackflies at the site. A total of 548 female adult blackflies were collected. The biting density of the flies ranged from 0.5 Flies/Man/Hour (FMH) in December to 5.5 FMH in January. The relative abundance of the flies ranged from 21 in December to 243 in January. Regression analysis showed that temperature and relative humidity had a positive correlation with relative abundance of Simulium damnosum complex (y =-0.0006x + 25.593, r = 0.0519) and (y =-0.1213x + 78.794, r = 0.505), respectively. Conclusions. The risk of getting infected with Onchocerca volvulus increased during the dry season with its associated weather conditions.

Introduction and objective. The effect of climatic conditions on the biting density and relative abundance of Simulium damnosum complex at Adani, Nigeria, from August 2010-January 2011 was investigated. Materials and methods: The classical method of collecting blackflies for a period of 11 hours using human attractants was employed in the study. Monthly climatic data, such as rainfall, relative humidity and temperature were collected for the period of study. Results. Rainfall, relative humidity, temperature, harmattan (cold, dry wind) and deforestation were observed to affect the biting density and relative abundance of blackflies at the site. A total of 548 female adult blackflies were collected. The biting density of the flies ranged from 0.5 Flies/Man/Hour (FMH) in December to 5.5 FMH in January. The relative abundance of the flies ranged from 21 in December to 243 in January. Regression analysis showed that temperature and relative humidity had a positive correlation with relative abundance of Simulium damnosum complex (y =-0.0006x + 25.593, r = 0.0519) and (y =-0.1213x + 78.794, r = 0.505), respectively. Conclusions. The risk of getting infected with Onchocerca volvulus increased during the dry season with its associated weather conditions.

Introduction and objective. The effect of climatic conditions on the biting density and relative abundance of Simulium damnosum complex at Adani, Nigeria, from August 2010-January 2011 was investigated. Materials and methods: The classical method of collecting blackflies for a period of 11 hours using human attractants was employed in the study. Monthly climatic data, such as rainfall, relative humidity and temperature were collected for the period of study. Results. Rainfall, relative humidity, temperature, harmattan (cold, dry wind) and deforestation were observed to affect the biting density and relative abundance of blackflies at the site. A total of 548 female adult blackflies were collected. The biting density of the flies ranged from 0.5 Flies/Man/Hour (FMH) in December to 5.5 FMH in January. The relative abundance of the flies ranged from 21 in December to 243 in January. Regression analysis showed that temperature and relative humidity had a positive correlation with relative abundance of Simulium damnosum complex (y =-0.0006x + 25.593, r = 0.0519) and (y =-0.1213x + 78.794, r = 0.505), respectively. Conclusions. The risk of getting infected with Onchocerca volvulus increased during the dry season with its associated weather conditions.

Effects of climatic conditions on the biting density and relative abundance of Simulium damnosum complex in a rural Nigerian farm settlement. Ann Agric Environ Med. 2014; 21(4): 699–702. Abstract Introduction and objective. The effect of climatic conditions on the biting density and relative abundance of Simulium damnosum complex at Adani, Nigeria, from August 2010 – January 2011 was investigated. Materials and methods: The classical method of collecting blackflies for a period of 11 hours using human attractants was employed in the study. Monthly climatic data, such as rainfall, relative humidity and temperature were collected for the period of study. Results. Rainfall, relative humidity, temperature, harmattan (cold, dry wind) and deforestation were observed to affect the biting density and relative abundance of blackflies at the site. Atotal of 548 female adult blackflies were collected. The biting density of the flies ranged from 0.5 Flies/Man/Hour (FMH) in December to 5.5 FMH i...

The effect of climatic conditions on the biting density and relative abundance of Simulium damnosum complex at Adani, Nigeria, from August 2010 -January 2011 was investigated. The classical method of collecting blackflies for a period of 11 hours using human attractants was employed in the study. Monthly climatic data, such as rainfall, relative humidity and temperature were collected for the period of study. Results. Rainfall, relative humidity, temperature, harmattan (cold, dry wind) and deforestation were observed to affect the biting density and relative abundance of blackflies at the site. A total of 548 female adult blackflies were collected. The biting density of the flies ranged from 0.5 Flies/Man/Hour (FMH) in December to 5.5 FMH in January. The relative abundance of the flies ranged from 21 in December to 243 in January. Regression analysis showed that temperature and relative humidity had a positive correlation with relative abundance of Simulium damnosum complex (y = -0.0006x + 25.593, r = 0.0519) and (y = -0.1213x + 78.794, r = 0.505), respectively. Conclusions. The risk of getting infected with Onchocerca volvulus increased during the dry season with its associated weather conditions.

Onchocerciasis is both public health hazard and socioeconomic problem despite concerted efforts and high expenditure on control programme. To assist with certification of elimination, cross sectional study was conducted at Ibii and Lolo Rivers, breeding sites of Simuluim damnosum in the Imo River Basin from September 2015 to February 2016. S. damnosum were caught by human bait technique and assessed for parity, infection and infectivity status. Biting rates and transmission potentials were calculated by standard methods. Of the 591 flies caught/dissected, 0.88% (5/591) were infected with sausage (L 1) and pre infective stage (L 2) but no infective stage (L 3). The distribution of O. volvulus at the two sites were insignificant (P>0.05). The diurnal biting activity exhibited a bimodal pattern with morning (9.00am and 10.00am) and evening (4.00pm and 5.00pm) peaks. Monthly biting rates (MBR) of 2,581 and 1877.25 bites / persons/ months were found for Ibii Original Research Article

Objectives: A longitudinal study was carried out to investigate the adult population dynamics and the physical and chemical factors affecting the distribution of Simulium damnosum complex, a vector of onchocerciasis (River blindness) along Osun river in a forest zone of southwestern Nigeria. Methods: Adult flies were collected on consented human baits from 7.00am to 6.00pm every fortnight at three communities; Osun Eleja, Osun Ogbere and Osun Budepo along Osun River from February 2008 to June 2009. Larval prospection was carried out in all accessible rivers around the study area and their physical-chemical parameters were determined. Results: A total of 1472 flies were caught during the study period with Osun Budepo accounting for the highest number of the flies (47.0%) followed by Osun Eleja (42.2%) and Osun Ogbere (10.8%). The fly abundance was significantly higher (p<0.05, respectively for the three sites) during the wet season, with a positive correlation between rainfall and...

This paper attempted to discuss the impact of climate change on human health. General effects such as variability in occurrence of numerous illnesses are linked to seasonal trends in temperatures, among others are discussed. Direct impact such as breakout and spread of cerebrospinal meningitis and others are highlighte d. The occurrence and spread of food and water-borne diseases as a result of climate change on human health include the spread of vector born diseases through its influence on the behaviours, and geographical distribution of vectors of parasitic diseases. It also affects the emergence and re-emergence of vector-borne diseases as the life cycle dynamics of vectors and parasites are altered. Recommendations such as primary health care structures should be strengthened through employment of qualified staff to be responsive to emergences associated with climate change, among others are proffered.

Background: Vector-biting behaviour is important for vector-borne disease (VBD) epidemiology. The proportion of blood meals taken on humans (the human blood index, HBI), is a component of the biting rate per vector on humans in VBD transmission models. Humans are the definitive host of Onchocerca volvulus, but the simuliid vectors feed on a range of animals and HBI is a key indicator of the potential for human onchocerciasis transmission. Ghana has a diversity of Simulium damnosum complex members, which are likely to vary in their HBIs, an important consideration for parameterization of onchocerciasis control and elimination models. Methods: Host-seeking and ovipositing S. damnosum sensu lato (s.l.) were collected from seven villages in four Ghanaian regions. Taxa were morphologically and molecularly identified. Blood meals from individually stored blackfly abdomens were used for DNA profiling, to identify previous host choice. Household, domestic animal, wild mammal and bird surveys were performed to estimate the density and diversity of potential blood hosts of blackflies. Results: A total of 11,107 abdomens of simuliid females (which would have obtained blood meal(s) previously) were tested, with blood meals successfully amplified in 3,772 (34%). A single-host species was identified in 2,857 (75.7%) of the blood meals, of which 2,162 (75.7%) were human. Simulium soubrense Beffa form, S. squamosum C and S. sanctipauli Pra form were the most anthropophagic (HBI = 0.92, 0.86 and 0.70, respectively); S. squamosum E, S. yahense and S. damnosum sensu stricto (s.s.)/S. sirbanum were the most zoophagic (HBI = 0.44, 0.53 and 0.63, respectively). The degree of anthropophagy decreased (but not statistically significantly) with increasing ratio of non-human/human blood hosts. Vector to human ratios ranged from 139 to 1,198 blackflies/person. Conclusions: DNA profiling can successfully identify blood meals from host-seeking and ovipositing blackflies. Host choice varies according to sibling species, season and capture site/method. There was no evidence that HBI is vector and/or host density dependent. Transmission breakpoints will vary among locations due to differing cytospecies compositions and vector abundances.

The biting preference of Simulium vectors has been known to influence the distribution of Onchocerca nodules and microfilariae in human body. There is, however, variation in biting pattern of Simulium flies in different geographical locations. This study investigates the biting pattern on human parts by Simulium vectors along Osun river system where Simulium soubrense Beffa form has been implicated as the dominant vector and its possible implication on the distribution of Onchocerca nodules on human body along the river. Flies were collected by consented fly capturers on exposed human parts namely head/neck region, arms, upper limb and lower limb in Osun Eleja and Osun Budepo along Osun river in the wet season (August-September) and the dry season (November-December) in 2008. The residents of the communities were also screened for palpable Onchocerca nodules. The results showed that number of flies collected below the ankle region was significantly higher than the number collected o...

The nuisance bites of blackflies and transmission of Onchocerca volvulus, which causes onchocerciasis, constitutes a threat to public health and an impediment to food production in rural and riverine communities in Nigeria. The entomological profile of onchocerciasis at Adani, Nigeria, was investigated from

Background and objectives: Onchocerciasis is an important threat to public health in Nigeria, which in turn contributes significantly to total world cases of the disease. This study determined the rate of transmission of onchocerciasis in Ahani-Achi, identified the principal vector groups of the disease in the study area and evaluated the relative abundance of black fly vectors and the various transmission indices.

Onchocerciasis is an important threat to public health in Nigeria, which in turn contributes significantly to total world cases of the disease. This study determined the rate of transmission of onchocerciasis in Ahani-Achi, identified the principal vector groups of the disease in the study area and evaluated the relative abundance of black fly vectors and the various transmission indices.

Onchocerciasis is endemic in some parts of Akwa Ibom State, Nigeria. This study describes the entomological parameters of transmission in three rural communities of Akwa Ibom State, prior to ivermectin intervention in 2004. Blackflies were caught using human bait and 90% of the flies were dissected for parity. All parous flies were further dissected for the presence of filaria larvae. Monthly and annual biting rate, and transmission potential were calculated using standard methods. A total of 4296 adult Simulium damnosum were caught on human bait, 4119 were dissected of which 208 (5.1%) were infected with Onchocerca volvulus larvae. Transmission parameters varied significantly (p < 0.05) in the three villages. Annual biting rates, ranged from 9490 to 11,218 bites per person per year. The annual transmission potential ranged from 131 to 189 infective larvae per person per year, monthly biting rate and monthly transmission potential varied significantly (p < 0.05) in the three v...

Studies on the morphometric characteristics of the Simulium vectors of onchocerciasis were carried out in Uzo-Uwani Local Government Area (LGA), Enugu State, Nigeria, between September 2008 and January 2009, with the objectives of identifying the sibling species present in the area and comparing the result obtained with cytological studies earlier done in the area. It was also meant to relate fly types with the types of onchocerciasis present in the area. The Simulium flies were collected using human baits. Seventy-five (75) flies were subjected to morphometric examinations. The thorax length, antenna length, wing length, wing width and femur length were measured and the data obtained were transformed into ratios. The morphometric studies on the Simulium damnosum populations in Nkpologu showed a higher abundance of savanna flies (54) than forest flies (21) among those sampled. The classification was done using the thorax length/antenna length (TL/AL) ratio. Discriminate function analysis revealed that 96.0% of originally grouped cases were correctly classified. The result agreed with cytotaxonomic studies on Simulium done in the area which showed predominance of savanna flies. The implications of the results are discussed.

Local disease perception and treatment of onchocerciasis were studied in Uzo-Uwani Local Government Area of Enugu State, Nigeria. The objectives of the study were to ascertain the level of understanding of the aetiology of onchocerciasis and the management of the disease in the area. Different sampling methods including cluster sampling and random sampling were used in the selection of the sample units. Data collection methods included the use of questionnaires and interviews. From the study, it was found that the people of the area are aware of the presence and nuisance value of Simulium flies, commonly called the b ackly, but do not associate the bite with the manifestations of onchocerciasis which are common in their communities. It was discovered that ignorance was at the root of many problems associated with Onchocerca volvulus disease such as discrimination against people with oncho-rashes, lack of proper treatment of the disease and abuse of the choice drug for treatment of onchocerciasis (ivermectin). Poverty is also a contributory factor to lack of adequate treatment of the disease in the area. The result also showed that nodulectomy is a common and accepted treatment method in the area for Onchocerca nodule. On the basis of the result, it is recommended that enlightenment programme is needed in the area together with a campaign for nodulectomy. In the enlightenment programme, use should be made of Community Directed Distributors already trained by World Health Organization (WHO) for the distribution of ivermectin under the African Programme for Onchocerciasis Control (APOC). l

The relative abundance of Simulium species in Dadinkowa river was assessed. Sixteen species of Simulium were encountered. The most abundant species found in the river were S.hargreavesi (52%), S. damnosum s.l. (24%) and S. vorax (11%). Species abundance varied significantly (P<0.01) within sampling sites of the same river and between different locations of the river. In the river system, S. hargreavesi was more abundant in stretches of the dam course of water velocity of 1.2 – 1.4m/sec., S. damnosum s.l. in 1.3 -1.5m/sec. while S. vorax was more common in water velocity of 1.1 -1.4m/sec. cytotaxonomic analysis of S. damnosum complex showed the presence of S. damnosum s.s, S. squamosum, S. sirbanum and S. sanctipauli in the river. These results were discussed in the light of the importance of relative abundance of black fly species in the transmission of Onchocerciasis (River blindness).

Seasonal bioaccumulation of heavy metals namely, Zinc (Zn), Iron (Fe), Copper (Cu), Lead (Pb), Mercury (Hg) and Arsenic (As) in the shellfish of Macrobrachium rosenbergi from Niger River at Onitsha were studied using Atomic Absorption Spectrophotometer (AAS). Results showed presence of all the analysed metals in the shellfish tissue. Mean concentrations of Zn (4.35±1.2mg/l), Cu (1.35±0.43), Cd (0.31±0.0421), Hg (0.16±0.0011) and As (0.04±0.001) in mg/l complied with the World Health Organization (WHO) standards in aquatic foods. However those for Fe (9.73±1.30) and Pb (0.24±0.04) mg/l exceeded the WHO standards. Furthermore, mean concentrations for Zn (0.321±0.09), Fe (1.52±0.07), Cu (0.035±0.006), Hg (0.076±0.007), As (0.016±0.007) and Cd (0.012±0.006) mg/l in the water columns were significantly lower (P&lt;0.05) than the concentrations in the shellfish. Bioaccumulation of heavy metals in the shellfish studied indicated that Niger River at Onitsha is experiencing impairment. The r...

The 72 man-hours of adult female Simulium damnosum collections between July and December 2006 gave the biting densities of 3.6, 1.1 and 0.2 flies per man-hour for Oji, Nachi and Umuabi communities, respectively. Biting activities started between 8.00 and 9.00 a.m. in these communities, peaked between 10.00 and 11.00 a.m. and declined with a little fluctuation until zero activity occurred from 6.00 p.m. The dissected 201, 65 and 9 flies from Oji, Nachi and Umuabi collections, respectively, yielded microfilaria infection rates of 12.9%, 13.9% and 0.0%. Biting density decreased with increasing distances from the Oji-River breeding focus.

Data on quantitative and qualitative studies that investigated knowledge, attitudes and practices (KAP) of humans affected with river blindness (Onchocerciasis) in Achiagu, Adani and Aguobuowa communities of Enugu State, south-eastern Nigeria were obtained in 2013 using a structured questionnaire, key format interviews and matrix ranking exercises. Ignorance of the role of blackfly Simulium damnosum complex in the transmission of the parasitic filarial worm Onchocerca volvulus that causes Onchocerciasis persisted in the study area. Intense sunshine, distant trekking, witchcraft, charms, heredity, intimate contact with affected humans, and food poisoning were believed by the people to be responsible for the infection. Loss of self-esteem, hindrance to marriage prospects, loss of income, absence from social gathering, and gender stigmatization of affected people ranked high among the perceived socio-economic and psychological impacts of Onchocerciasis in the area. Treatment by nodulec...

Background: Entomological indicators are considered key metrics to document the interruption of transmission of Onchocerca volvulus, the etiological agent of human onchocerciasis. Human landing collection is the standard employed for collection of the vectors for this parasite. Recent studies reported the development of traps that have the potential for replacing humans for surveillance of O. volvulus in the vector population. However, the key chemical components of human odor that are attractive to vector black flies have not been identified.

Seasonal fluctuations of the Simulium damnosum Theobald complex and the prevalence of Onchocerca volvulus Bickel in blackflies caught in river systems bordering the Nigeria -Benin border were assessed for their direct impact on the epidemiology of onchocerciasis in South-western Nigeria. Entomological evaluation and heteroduplex assay (HDA) techniques were performed on flies caught in the eight capture points in the Ogun and Yewa river systems between A total of 5789 blackflies were caught on human bait, of which 727 (12.6%) flies were captured in 2007, 1723 (29.8%) in 2008 and 3339 (57.6%) in 2009. The majority of flies caught during the study were forest flies representing 90.3% of the total catch while savanna flies constituted 9.7%. Proportions of parous to nulliparous flies were low in all the catching points (31.1 and 68.9%, respectively). Of the 5789 flies dissected, 11 (0.2%) flies were infected with Onchocerca parasites with nine of the infected flies having L3 head parasites. The HDA results revealed that the Beffa form of S. soubrense was the dominant cytospecies present (87.1%) in all the capture sites when compared with 12.9% of S. damnosum s.s. The low level of infectivity of flies may therefore indicate a low transmission level of onchocerciasis in the communities along the Ogun and Yewa river systems. However, there is a need for constant surveillance on species composition and fly infectivity in the river systems along the borders of Nigeria -Benin Republic.

This study was carried out between February 2014 and January 2015 to investigate the morphology of Simulium damnosum s.l. populations along Kwa Falls and Rhoko river in Akamkpa Local Government Area of Cross River State, Nigeria, in relation to the strain of Onchocerca volvulus transmitted in the study area.  Two fly boys working on shift of 6 hours captured Simulium flies settling on them for blood meals by inverting specimen vials over them. Simulium flies were preserved in 70% ethanol and transported to the Biological Science Laboratory of Cross River University of Technology, Calabar, for entomological studies. Of the 265 Simulium species studied, 29 species were identified as savanna-dwellers, 98 species as transition zone dwellers and 138 species as forest-dwellers. There was significant difference (p<0.001) in the wing tufts colour but no significant difference (p>0.05) between blackflies from these rivers. Mean thorax/antenna ratios of 2.4143, 1.9673, and 2.033 were recorded for savanna dwellers, transition zone dwellers and forest species respectively. Based on the morphology of Simulium damnosum s.l. studied, it could be inferred that there are likely four Simulium sibling species related to Simulium sirbanum, S. squamosum, S. yahense and S. damnosum sensu stricto in the study area.

Background: Entomological indicators are considered key metrics to document the interruption of transmission of Onchocerca volvulus, the etiological agent of human onchocerciasis. Human landing collection is the standard employed for collection of the vectors for this parasite. Recent studies reported the development of traps that have the potential for replacing humans for surveillance of O. volvulus in the vector population. However, the key chemical components of human odor that are attractive to vector black flies have not been identified.

Introduction and objective. The effect of climatic conditions on the biting density and relative abundance of Simulium
damnosum complex at Adani, Nigeria, from August 2010 – January 2011 was investigated.
Materials and methods: The classical method of collecting blackflies for a period of 11 hours using human attractants
was employed in the study. Monthly climatic data, such as rainfall, relative humidity and temperature were collected for
the period of study.
Results. Rainfall, relative humidity, temperature, harmattan (cold, dry wind) and deforestation were observed to affect the
biting density and relative abundance of blackflies at the site. A total of 548 female adult blackflies were collected. The biting density of the flies ranged from 0.5 Flies/Man/Hour (FMH) in December to 5.5 FMH in January. The relative abundance of the flies ranged from 21 in December to 243 in January. Regression analysis showed that temperature and relative humidity had a positive correlation with relative abundance of Simulium damnosum complex (y = -0.0006x + 25.593, r = 0.0519) and (y = -0.1213x + 78.794, r = 0.505), respectively.
Conclusions. The risk of getting infected with Onchocerca volvulus increased during the dry season with its associated
weather conditions.

Background: Studies on biting behaviours and infectivity status of insect vectors are pre-requisites in understanding the epidemiology of the vector-borne diseases and planning effective control measures. A longitudinal study was carried out to investigate the transmission index of Simulium damnosum complex species along Osun River, South Western Nigeria. Adult flies were collected on human attractants from 07:00 to 18:00 hours for two consecutive days from February 2008 to June 2009 at three communities: Osun Eleja, Osun Ogbere and Osun Budepo. The infectivity rate was determined by dissection and Polymerase Chain Reaction amplification (PCR) of 0-150 genes of Onchocerca parasite using the pool screening technique.