First Time In Nigeria Research Articles

Occult Hepatitis B virus infection in previously screened, blood donors in Ile-Ife, Nigeria: implications for blood transfusion and stem cell transplantation.

BackgroundHepatitis B virus (HBV) transmission through blood transfusion is reduced by screening for hepatitis B surface antigen (HBsAg). However this method cannot detect the presence of occult hepatitis B virus infection. This study sought to determine the prevalence of occult hepatitis B virus infection among blood donors in Ile-Ife, Nigeria. For the first time in Nigeria we employed an automated real-time PCR- method to investigate the prevalence of occult HBV in blood donors.MethodsBlood donors screened with HBsAg immunochromatographic rapid test kits at the blood transfusion units of two hospitals and found to be negative were recruited into the study. Questionnaires to elicit risk factors for HBV infection were administered and then 10 ml of blood was collected from each donor. Plasma samples obtained from these HBsAg negative blood donors were screened again for HBsAg using an enzyme-linked immunosorbent assay (ELISA) method, and those found negative were screened for the presence of total antibody to the HBV core antigen (anti-HBc) using ELISA method. Those positive to anti-HBc were then tested for HBV DNA, using an automated real-time PCR method.ResultsFive hundred and seven blood donors found HBsAg negative by immunochromatographic rapid test kits at both blood transfusion units, were tested for HBsAg using ELISA and 5 (1 %) were HBsAg positive. The 502 found negative were tested for anti-HBc and 354 (70.5 %) were found positive implying previous exposure to HBV and 19 (5.4 %) of the 354 anti-HBc positive had HBV DNA signifying occult HBV infection. No risk factors were found to be associated with the presence of HBV DNA among those who tested positive.ConclusionOccult HBV infection exists in blood donors in Ile-Ife, Nigeria and the use of HBsAg alone for screening prospective donors will not eliminate the risk of HBV transmission in blood transfusion or stem cell transplantation.

Enterovirus Species B Bias of RD Cell Line and Its Influence on Enterovirus Diversity Landscape.

Despite its widespread use in poliovirus isolation, studies show that most RD cell line isolates are species B enteroviruses (EB), it was therefore employed to further catalogue the EB diversity in two different regions of Nigeria. Concentrates of 18 environmental samples were inoculated into RD cell line. Isolates were subjected to PCR assays to detect enteroviruses, species C and B members and partial VP1 gene which was subsequently sequenced and used for identification and phylogenetic analysis. Isolates were further passaged in L20B cell line to detect polioviruses. Sixty-eight isolates were recovered from the 18 concentrates, all of which were positive for the enterovirus 5'-UTR screen. Thirteen of the 68 isolates were positive for the species C screen and replicated in L20B cell line, eleven of which also contained species B enteroviruses. Some of the mixed isolates were successfully typed, but as species B members. In all, isolates recovered in this study were identified as CVB5, E6, E7, E11, E13, E19, E20, E33, EVB75 and WPV3, while some could not be typed. Alongside the ten different enterovirus serotypes confirmed, results of this study document for the first time in Nigeria, EVB75. It showed the EB bias of RD cell line might indicate something much more fundamental in its biology. Finally, the finding of WPV3 in a region considered low risk for poliovirus emphasizes the need to expand poliovirus environmental surveillance to enable early detection of poliovirus silent circulation before occurrence of clinical manifestations.

Molecular Detection and Characterization of Bm86 Gene Homologues from Hyalomma truncatum, Rhipicephalus (Boophilus) annulatus and Rhipicephalus (Boophilus) decoloratus for the Development of an Anti-Tick Vaccine in Nigeria

The current study was conducted using prevalent Ixodid ticks from the Jos Plateau, were largely the use of acaricides has a number of drawbacks which include the development of resistant ticks, environmental pollution and toxicity. The molecular detection and characterization of Bm86 gene homologues in Hyalomma truncutum, Rhipicephalus (Boophilus) decoloratus and Rhipicephalus (Boophilus) annulatus for the first time in Nigeria was achieved and significantly important in the quest for alternative tick control strategies. GenBank Accession numbers has been assigned to the homologues as KF670599, KF670600 and KF670601 respectively and deposited as well. These results might assist in the development of a recombinant Bm86 gene based anti-tick vaccine which is an important component of an integrated control measure against hard ticks infesting livestock in the sub-Saharan Africa.

The bionomics and diversity of freshwater snails species in Yewa North, Ogun State, Southwestern Nigeria

Abstract Snail control as a form of integrated control for schistosomiasis has been strongly advocated but data on biocontrol using competitor snails are relatively lacking in most endemic areas. Monthly sampling of freshwater snails was conducted in four water bodies in Yewa North Local Government Area, Ogun State, Nigeria. Monthly in situ measurements of the physico-chemical characteristics of surface waters were carried out using field meters. A total number of 13 snail species were recovered from the water bodies. Of these, Bulinus camerunensis was reported for the first time in Nigeria. A significant positive relationship occurred between snail density and dissolved oxygen. Other important relationships were those between Lanistes lybicus and Bulinus senegalensis, Bulinus globosus and Bulinus jousseaumei, and B. senegalensis and Segmentorbis augustus. Snail control using competitor snails should be integrated into schistosomiasis management programmes in endemic areas in order to prevent residual schistosomiasis transmission after control intervention through mass drug treatment.

Molecular epidemiology of rotavirus and norovirus in Ile‐Ife, Nigeria: High prevalence of G12P[8] rotavirus strains and detection of a rare norovirus genotype

Rotavirus (RV) and norovirus (NoV) are considered the most common causes of viral gastroenteritis in children. In this study, the prevalence of RV and NoV infection in 55 children with diarrhea from the rural community Akinlalu in Southwestern Nigeria was investigated using real-time PCR assays. The RV and NoV strains were genotyped by PCR and/or sequencing. RV and NoV infections occurred with a prevalence of 34.5% and 25.5% respectively, with predominance in children <1 year. Most infections occurred during the dry season with increasing prevalence of RV as the dry season progressed (October-January). Infections with RV VP6 subgroup (SG) II were more prevalent (27.3%) than SGI (7.3%). Similarly, NoV genogroup II infections were more common (23.6%) than genogroup I (1.8%). Five children out of 55 (9.1%) were co-infected with both RV and NoV. Notably, G12P[8] was the predominant RV strain (36.8%, n = 7), observed for the first time in Nigeria. The VP7 gene of the G12 strains clustered within lineage III, sharing high nucleotide identity with each other (>99%) indicating introduction in Nigeria from a single donor. Furthermore, a putative novel genotype within genogroup I NoV was detected, which till date has only been reported once in humans. To conclude, a high prevalence of the emerging G12P[8] RV strain was observed for the first time in Nigeria, as well as a putative novel NoV genotype in humans. These results provide new information which can be important for future vaccine evaluations and possible introduction in Nigeria.

Experiences in Establishing a PEPFAR-Supported Laboratory Quality System in Nigeria

The need to accurately diagnose HIV-infected persons and monitor their immune status and sequelae from increased access to antiretroviral therapy dictated the establishment of a quality assurance (QA) system supported by dedicated personnel, financial resources, and a close monitoring system. Assessment of laboratories and personnel in Nigeria revealed the need for improved laboratory infrastructure and training, including on-site didactic and wet workshops and the institution of a tiered QA unit of laboratory regional officers, focal persons, and site monitors who provided guidance and continuous monitoring. Quarterly assessments and generated reports guided corrective actions. A sustainable quality laboratory system was developed for the first time in Nigeria with funding from the US President's Emergency Plan for AIDS Relief. With expansion from 7 to 34 comprehensive treatment sites, a tiered laboratory organizational structure with regional and site-based Nigerian quality control officers was developed. Measured improvements included reduction in deficiencies from 13% to 2%.

Agbami Project: People and Partnerships Deliver a World-Scale Field Development

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper OTC 20249, "Agbami Project: People and Partnerships Delivering a World-Scale Field Development," by C.D. Bloomer, Chevron Project Resources Company, originally prepared for the 2009 Offshore Technology Conference, Houston, 4–7 May. The paper has not been peer reviewed. The Agbami project successfully began production in July 2008, 10 years after the discovery of this world-class reservoir. Agbami represents one of Chevron Corporation's largest capital investments of the decade and the project achieved many outstanding results, overcoming various challenges along the way. The full-length paper provides an overview of the project and discusses the key project objectives, strategies used, and some of the lessons learned. Introduction The Agbami field sits 70 miles offshore Nigeria in approximately 5,000-ft water depth. The reservoir is a doubly plunging, thrust-faulted anticline comprising four main reservoirs. The crude is light and sweet, 47°API. The selected development plan includes a floating production, storage, and offloading (FPSO) vessel and subsea well completions. The FPSO has an oil-production capacity of 250,000 BOPD, gas-injection capacity of 415 MMscf/D, and water-injection capacity of 450,000 BWPD. The combined production capacity of the FPSO ranks as the largest in the world. Crestal gas injection provides pressure maintenance for the reservoir as well as preventing routine flaring of associated gas. Peripheral water injection also provides pressure maintenance. An estimated 38 wells eventually will be needed to develop the reserves fully. Nigerian Content The Agbami project made an early decision to achieve a new standard in Nigerian Content. Nigerian Content is a critical government objective to expand the economic benefits of project development and to build capacity in the people and businesses of Nigeria. The Agbami team embraced Nigerian Content as a strategic objective for project success, rather than as a government-imposed mandate. Agbami benchmarked the Nigerian Content of predecessor projects and established a Nigerian Content plan approximately 50% higher than previous accomplishments. These requirements were part of the project contracts, and all contractors understood the importance of delivering this objective. As a result, five modules for the FPSO were fabricated in Warri and Lagos, including the largest FPSO module (weighing more than 1,700 tons) built to date in Nigeria. For the first time in Nigeria, the stainless-steel-clad sub-sea manifolds were fabricated in Port Harcourt. In addition, the offloading buoy and mooring piles were fabricated in Lagos. Significant investment and capacity building occurred across the Nigerian yards to fabricate these facilities. In all, the Nigerian Content exceeded 10,000 tons of fabrication, employing more than 4 million man-hours with zero days-away-from work (DAFW) injuries. The goal was aggressive and led to challenges along the way, but it was successful because it was a reasonable plan that had the support of all partners.

Micrometeorological measurements in Nigeria during the total solar eclipse of 29 March, 2006

The total solar eclipse of 29 March, 2006 which was visible at Ibadan (7.55°N, 4.56°E), south-western Nigeria was utilized to document atmospheric surface-layer effects of the eclipse for the first time in Nigeria. The meteorological parameters measured are global radiation, net radiation, wind speed (at different heights), atmospheric pressure and soil temperature (5, 10 and 30 cm), moisture and heat flux and rainfall. The results revealed remarkable dynamic atmospheric effects. The observations showed that the incoming solar radiation, net radiation and air temperature were significantly affected. There was an upsurge of wind speed just before the first contact of the eclipse followed by a very sharp decrease in wind speed due to the cooling and stabilization of the atmospheric boundary layer. The atmospheric pressure lags the eclipse maximum by 1 h 30 min, while the soil temperature at 5 and 10 cm remain constant during the maximum phase of the eclipse.

The first report of Histophilus somni pneumonia in Nigerian dairy cattle

Clinical signs of severe bronchopneumonia, including anorexia, coughing, nasal discharge, dyspnoea, diarrhoea, distension of the neck, lethargy, recumbency, lameness preceding collapse, and death were observed among a herd of Holstein–Friesian dairy cattle. The outbreak occurred over a 30-day period, and attack and case-fatality rates were 0.4% and 50%, respectively. At necropsy, extensive consolidation in the cranioventral parts of the lungs was observed. Histologically, a severe acute bronchopneumonia with slight pleuritis was present. Both pathological and bacteriological evaluation of the lungs incriminated Histophilus somni (heavy growth). Supplementary laboratory investigations also isolated Clostridium and Klebsiella species (scanty growth) from the lungs. Histophilosis in cattle was confirmed for the first time in Nigeria.

Epidemiology of dermatophytoses in a rural community in Eastern Nigeria and review of literature from Africa

A total of 4,287 primary school children, comprising 1,740 males and 2,547 females in Arochukwu local government area of Abia state Nigeria were examined for clinical signs of dermatophytoses. About 873 (20.4%), consisting of 505 males and 368 females had lesions consistent with dermatophytoses. The disease was more prevalent in males (29%) than females (14.4%) in a ratio of approximately 2:1 (P < 0.05). The infection rate increased from 16.8% in the 4-6 year age group to a peak of 28.1% in the 10-12 year age bracket and dropped sharply to 5.6% in the 16-18 year group. The highest prevalence (39%) was observed among males aged 10-12 years while females 16-18 years had the lowest prevalence (2.5%). Tinea capitis was the predominant clinical type of dermatophytoses, and occurred in 13.7% of the total population studied and 67% of lesion positive cases. Trichophyton soudanense and Trichophyton tonsurans the predominant aetiological agents of dermatophytoses with a prevalence of 26.2% and 21.6%, respectively. Others include Trichophyton mentagrophytes (18.8%), Epidermophyton floccosum (8.3%), Microsporum audouinii (6.4%), Microsporum gypseum (6.0%), Trichophyton rubrum (5.5%) and Microsporum ferrugineum (7.3%), which was isolated for the first time in Nigeria.

Yeast associated with human infections in south‐eastern Nigeria

A total of 1921 specimens from nine clinical sources were examined by direct microscopy and culture to recover yeast associated with human infection. Identification of yeast was based on their carbon assimilation patterns, using API 20C AUX and ID 32 C (bioMérieux, France) commercial kits. A total of 178 specimens (9.3%) were positive for yeast. Most of the yeast isolates were recovered from urine samples and genital swabs. Prevalence was significantly higher in women (14.7%) than in men (1.4%) (P < 0.05). The age group 21-30 years recorded the highest prevalence of yeast infection (65.2%) followed by age group 11-20 years (16.9%) and > 40 years (9.0%). When genital samples were considered, prevalence was significantly higher in the age group 21-30 years than that in older ones (P < 0.05). Isolates recovered included seven species of Candida and Trichosporon inkin. C. albicans accounted for the highest number of isolates (128) followed by C. tropicalis (23) and C. parapsilosis (9). Two isolates each of C. famata and C. norvegensis were recorded and are reported for the first time in Nigeria. The two isolates of T. inkin were recovered from perianal lesions and are also reported for the first time from Nigeria. C. albicans, C. glabrata, C. parapsilosis and C. krusei were found to be the most common yeast species that act as agents of human disease in south-eastern Nigeria.

Cytospecies Identifications of Vectors of Human Onchocerciasis in South Eastern Nigeria

Cytogenetic studies were carried out on the larvae of the members of the Simulium damnosum complex from 10 sites across the different bioecological zones in Southeast Nigeria. A total of 334 identifications belonging to 3 cytospecies (S.squamosum, S. yahense and S. damnosum) were made. The ICb variant of S.squamosum was observed for the first time in Nigeria. The seasonal abundance and geographical distribution of the sibling species generally conformed to that which had been observed further west in the OCP area, with the exception of S. damnosum, which was generally more plastic in its distribution. Key words: Simulium damnosum complex, S. squamosum, S. yahense, cytogenetics, sibling species, cytospecies.

Changes in the rotifers of Ikpoba River Dam, Benin City, southern Nigeria

Plankton samples were taken fortnightly from the Ikpoba River Dam from February to June 1992 to determine changes in the rotifer community. Fifty-three species of rotifers belonging to thirteen families were identified. One species, Macrochaetus subquadratus of the family Trichotridae was recorded for the first time in Nigeria. In addition to this, eight species, Lecane ohionesis, L. elsa, L. signifera, Keratella lenzi, K. cochlearis, Lepadella cristata, Colurella padulosa and Vonoyella globosa were recorded for the first time in the dam. An important aspect of the changes is in its species composition. The family Lecanidae, was the most abundant in terms of species composition. An entirely new family, Proalidae in the system is the most abundant in terms of abundance. This high number was contributed by only four species. Thus the appearance of new species and the disappearance of existing ones have been an important aspect of the changes in the specific composition of rotifers from what existed in 1982. Key Words: Rotifers, dam, population change, checklist, identification. Tropical Freshwater Biology 11 (2002) 37-46

OCCURRENCE AND PREVALENCE OF VIRUSES OF LEAFY VEGETABLES IN LAGOS, NIGERIA

Four commercial leafy vegetable farms in Lagos State were surveyed from October 1989 to September 1990 for the occurrence and prevalence of leafy vegetable viruses. Mechanically transmissible viruses were isolated from Amaranthus hybridus, Celosia argentea, Cucurbita moschata, Telfairia occidentalis and Brassica oleracea, while virus-like symptoms (causal agents not sap-transmissible), were observed on Solanum macrocarpon. Two previously uncharacterized viruses, one each from C. argentea and C. moschata were isolated. The identification of viruses such as telfairia mosaic virus (TeMV) and amaranthus mosaic virus (AMV), that had been reported in the literature, were confirmed on the basis of host range, symptomatology, insect transmission and particle morphology. Virus-like symptoms were not observed on Corchorus olitorus and five other exotic vegetables. Amaranthus mosaic virus and celosia mosaic virus (ClMV), the latter isolated for the first time in Nigeria in the course of this study, were recorded from all the farms and were therefore the most prevalent. The incidence of AMV was 19.7% at Amuwo Odofin while it was 0.7% and 0.6% at Tejuoso and Abule Ado farms respectively. For ClMV, an incidence of 27.5% was recorded at Amuwo Odofin while Tejuoso and Abule Ado had 0.6% and 1.4% respectively. Telfairia mosaic virus and viruses on C. moschata and B. oleracea were limited to the Tejuoso farm. Generally, virus incidence was higher during the wet season for most of the viruses. Elimination of plant remains and volunteer crops may be exploited in the control of the viruses. KEY WORDS: Survey, Leafy vegetables, viruses. Global Jnl Pure & Applied Sciences Vol.10(1) 2004: 61-67

FUNGAL DISEASES OF RICE IN NURSERY FARMS IN BAYELSA STATE OF NIGERIA

A survey of fungi association with seed, seedling and straw samples of three rice varieties (Faro 12, Faro 15, and Maliong) obtained from 18 nursery farms in Okuokpoti-Ogbia, a major rice producing community in Ogbia Local Government area of Bayelsa State, Nigeria was investigated. Soil samples from the farms were also tested for fungi. A total of 36 samples were tested per study parameter per rice variety. The standard blotter method was used to test the seed, seedling, and straw samples and the soil samples were tested using the serial dilution plate technique on acidified potato dextrose agar (APDA) medium in Petri dishes. Botryodiplodia theobromae, Fusarium moniliforme, Fusarium oxysporum, Glomerella cingulata and Penicillium oxalicum were detected in seed and seedling samples of the three rice varieties at varying percentage. Fusarium oxysporum gave the highest percentage occurrence in seeds (48.7%) and seedlings (44.4%) while F. moniliforme gave the lowest percentage occurrence in seeds (19.1%) and seedlings (16.7%). Botryodiplodia theobromae (44.4%), F. moniliforme (5.6%), F. oxysporum (33.5%) and P. oxalicum (10.7%) were isolated from soil samples. All the fungi isolated were found to be seed-borne, seed transmissible and pathogenic except P. oxalicum which was not pathogenic. Botryodiplodia theobromae and G. cingulata which are important pathogens of legumes, root and tuber crops in the tropics and subtropics are reported to be pathogenic on rice for the first time in Nigeria. This is probably due to mixed cropping system. The significance of seed health testing in agricultural production and economy is discussed. KEY WORDS: Fungal disease, rice, Bayelsa State, nursery farms, Nigeria. Global Journal of Agricultural Sciences Vol.2(2) 2003: 90-92

Diversity of human rotavirus VP6, VP7, and VP4 in Lagos State, Nigeria.

This study investigated the diversity of rotavirus strains recovered from young children in Lagos, Nigeria, during December 1996-January 1997. In total, 287 children, aged 1-60 month(s), presenting with diarrhoea to the Gbaja Health Centre of Massey Street Children Hospital and the Lagos University Teaching Hospital, were included in the study. Rotavirus-positive specimens were characterized by monoclonal antibody enzyme-linked immunosorbent assay (ELISA) for VP6 subgroup and VP7 serotype and by polymerase chain reaction (PCR) for VP4 genotype and VP7 strains (that were non-reactive to ELISA). Of 84 samples tested for VP6 subgroup epitope, subgroup II was predominant (51%) with only a few subgroup I strains (4%), while many could not be typed at all (45%). For the VP7 serotypes, G1 was the most prevalent strain (45%), followed by G3 strains (5%). Neither G2 nor G4 strains were found, although mixed G1/G2 has been reported for the first time in Nigeria. Of strains that were non-reactive to ELISA, 29 (34%) could not be typed by PCR for G type. A subset of 23 samples was selected on the basis of RNA electropherotype, VP7 serotype, and included nine strains of VP7 that were non-reactive to ELISA. VP4 genotype of this subset was determined by PCR, and the most prevalent genotype was P[6] (30%), followed by P[8] (26%). Only one P[4] strain was identified. This study has shown the diversity of rotavirus strains circulating in West Africa.

A Cowpea Seed Rot Disease Caused by Fusarium equiseti Identified in Nigeria.

Fusarium equiseti (Corda) Sacc., reported on cowpea (Vigna unguiculata (L.) Walp.) seeds in India (2), was isolated for the first time in Nigeria from naturally infected cowpea seeds. Cowpea, cv. IT90K-76, seeds (400) from plants grown in Nigeria were surface-disinfested in 0.05% NaOCl and placed on moist filter paper in petri dishes (10 seeds per dish) and then in a dark incubator for 4 days at 27°C. After incubation, some seeds had fungal mycelia growing on their surfaces. When cultured on potato dextrose (PDA) and Spezieller Nährstoffarmer (SNA) agars, the fungi produced macroconidia characteristic of F. equiseti (1). Septate macroconidia were three to six celled with extended apical and distinctive foot-shaped basal cells. F. equiseti was recovered from 4.25% of seeds, and incidence correlated positively with development of seed rot symptoms. To confirm pathogenicity, 80 cowpea seeds were surface-disinfested with NaOCl, and 40 were soaked for 6 h in a suspension of 3 × 105 conidia of F. equiseti per ml of water. The remaining seeds were soaked in sterile distilled water. After incubation, white mycelia developed on 87.5% of seeds soaked in the conidial suspension and rotted without germinating. Only 5% of seeds soaked in sterile water developed seed rot symptoms. When cultured on PDA and SNA, fungi isolated from artificially infested seeds with rot symptoms again were identified as F. equiseti.

Corynespora cassiicola leaf spot of pawpaw (Carica papaya L.) in Nigeria.

Leaf spot of pawpaw is hereby reported for the first time in Nigeria. The symptom is characterized by a papery center surrounded by a yellow halo. The causal organism is Corynespora cassiicola. Ripe fruits and abaxial surfaces of the leaves were significantly more susceptible to infection than unripe fruits and adaxial surfaces of leaves. Growth and sporulation of the fungus on several media was investigated. The organism grew faster on malt-extract agar (MEA) derived media and slowest on potato-dextrose agar (PDA) supplemented with thiamine. Sporulation was highest on Czapek-dox agar (CDA) plus biotin and lowest on PDA and PDA + thiamine. Reasons for increased susceptibility of ripe fruit are discussed.

Prevalence and seasonal changes in the gastro-intestinal helminths of Nigerian goats.

A total of 120 gastro-intestinal tracts and 960 faecal samples were examined to assess the prevalence and seasonal changes in the gastro-intestinal helminth parasites of Red Sokoto (maradi) goats slaughtered at Ibadan between May 1991 and April 1992. Egg types of strongyles, Strongyloides, Trichuris, Skrjabinema, Dicrocoelium and Moniezia were encountered in 93%, 83%, 44%, 0.9%, 2.3% and 31% of the faecal samples respectively. However, only strongyle, Strongyloides and Trichuris eggs occurred in large numbers and were more common during the rainy season than in the dry season. The parasites recorded and their prevalences were Haemonchus contortus (90.0%), H. ovis (5.0%), Strongyloides papillosus (80.8%), Trichostrongylus colubriformis (78.3%), T. axei (69.2%), Trichuris ovis (72.5%), T. globulosa (38.3%), Oesophagostomum columbianum (67.5%), Cooperia curticei (58.3%) Gaigeria pachyscelis (40.8%), Skrjabinema ovis (5.0%), Nematodirus battus (5.8%), Moniezia expansa (29.2%), M. benedeni (10.0%), Paramphistomum spp. (5.0%) and Cysticercus tenuicollis (33.3%). Haemonchus ovis is reported for the first time in Nigeria. Mixed infections were most prevalent. Young goats were more commonly infected and had higher worm counts than adult goats. Only Haemonchus, Trichostrongylus, Strongyloides and Cooperia spp. occurred in large numbers. Irrespective of the age of the goats, higher worm counts were generally encountered during the rainy season than in the dry season. The results are discussed in relation to the control of helminthiasis in grazing animals in Nigeria.

Salinity and the distribution of rotifers in the Lagos Harbour ? Badagry Creek system, Nigeria

The waters of Lagos Harbour have a salinity variation of 30‰, as a consequence of the annual rainfall regime and of the influx of Atlantic Ocean waters. We made monthly plankton hauls at 10 stations for 11 months starting in October 1986, and found 51 species of rotifers, with Brachionus baylyi Sudzuki & Timms, Keratella hispida Lauterborn, Colurella obtusa Gosse, and Filinia pejleri Hutchinson recorded for the first time in Nigeria. In distribution, species numbers decreased with increasing salinity. Brachionus plicatilis, B. rubens, Hexarthra intermedia, Keratella americana, K. cochlearis and K. tropica were classed as euryhaline. Stenohaline species were Anuraeopsis fissa, Ascomorpha ovalis, Filinia longiseta, F. opoliensis, Gastropus sp., Lecane curvicornis and Monostyla stenroosi. All other monogononts were restricted to waters of salinity below 1‰.