Distribution of ocular perfusion pressure and its relationship with intraocular pressure in patients with primary open angle glaucoma in Enugu, South East, Nigeria.

Background: Ocular perfusion pressure (OPP) has been suggested as a possible risk factor for the development and progression of primary open angle glaucoma (POAG). Aim: To determine the distribution of OPP and its relationship with intraocular pressure (IOP) in Nigerian patients with POAG. Patients and Methods: : A descriptive and comparative survey was adopted. A total of 120 subjects, 60 newly diagnosed POAG and 60 non-glaucomatous (NG) subjects, aged 40 years and above, who attended the ophthalmic clinic of University of Nigeria Teaching Hospital Enugu were recruited over a six-month period in 2019. All the subjects had ocular examination, blood pressure and IOP measurements. Statistical package for social sciences software version 25 was used for data analysis. Chi-square test, independent samples t-test, and Mann-Whitney U test were used for comparison while Pearson correlation and simple linear regression were used to ascertain the relationship. A P value of <0.05 was considered significant. Result: The mean age of the participants was 57.9 + 11.9 years. The mean OPP was found to be significantly lower in the POAG subjects (Right eye, R = 43.6 ± 12.6, Left eye, L = 41.9 ± 13.3) mmHg compared with the NG group (R = 53.9 ± 10.9, L = 53.7 ± 10.9) mmHg (p < 0.001 for both eyes). A significant inverse relationship was observed between OPP and IOP in POAG subjects (p < 0.001), while there was none in NG subjects. Conclusion: OPP was lower in POAG subjects than in NG subjects. The observed relationship suggests that reduced OPP may play a role in the development of POAG.

Spectacle design preferences among school children in Enugu State, Nigeria.

BACKGROUND: Uncorrected refractive error has profound effects on children's educational and social development and spectacles are cost-effective in correcting this. However, the cosmetic appearance of spectacles may affect compliance to prescribed spectacles. AIMS: This study explored spectacle design preferences of school children in Enugu State, Nigeria and any associated sociodemographic factors. A cross-sectional study among children aged 5-15 years from schools in Enugu state, Nigeria. PATIENTS AND METHODS: The children independently selected from sets of spectacle frames, indicating their preferences on the basis of spectacle frame color, material, shape and size of the lens portion, design of the earpiece portions. Simple descriptive analysis was performed. Frequency tables were generated. Pearson's Chi-square test was used to test associations between categorical variables. Odds ratios were used to measure the strength of the associations where P < 0.05. Tests of significance were set at the 95% level. RESULTS: A total of 1,167 children (45.6% male and 54.4% female) were seen. Majority of the children preferred red colored spectacle frames 467 (40%), plastic frames 723 (62%), rectangular shaped lens-pieces (55.2%), and frames with a straight earpiece 987 (84.6%). There is a strong association between gender and choice of spectacle colour (P < 0.01), gender and lens size preference (P < 0.05), and between school location and shapes of spectacle earpiece (P < 0.01). CONCLUSIONS: Spectacle preferences exist among the study population and some demographic factors are associated with these preferences which should be considered in any childhood refractive error services.

Prevalence of refractive errors and visual impairment in school children in Enugu South-East Nigeria.

AIMS: To determine the prevalence of refractive errors and causes of visual impairment in school children in Enugu State, South-eastern Nigeria. METHODS: A descriptive cross-sectional, school-based survey in children aged 5-15 years from selected primary and junior secondary schools (public and private) in both urban and rural communities of Enugu State was carried out. Ocular examinations were performed on them according to the Refractive Error in School-age Children (RESC) protocol. RESULTS: A total of 1167 children were examined. The mean age (standard deviation) was 10.58 ± 3.0 years. Females were 653 (54.4%) of the study population. The uncorrected, presenting and best-corrected visual acuity of ≤20/40 (6/12) in the better eye of the children in this study were 3.6%. 3.5% and 0.4%. Among the children that had visual impairment, refractive error accounted for 33.3% of reduced vision while the overall prevalence of refractive error was 2.1%. Prevalence of myopia was 1.9% and hyperopia, 0.1%. The most prevalent astigmatism was ≤0.75 dioptre cylinder. CONCLUSION: The prevalence of refractive error in this study is low, with myopia being more common. Despite the low prevalence of refractive error, school vision screening is still important for African children as it serves as an opportunity to identify other ocular morbidities among the children.

Conjunctival bacterial flora and their antibiotic sensitivity among patients scheduled for cataract surgery in a tertiary hospital in south-east Nigeria.

PURPOSE: To determine the pre-operative conjunctival bacteria flora and their antibiotic susceptibility among patients scheduled for cataract surgery. METHODS: A descriptive, cross-sectional, hospital-based study design was adopted. It involved 104 consecutive, consented patients scheduled for cataract surgery at the University of Nigeria Teaching Hospital Enugu, from June to September 2017. The participants' socio-demographic characteristics, medical, and social history were obtained through interviewer-administered questionnaire. Conjunctival swab was obtained from the inferior fornix of the eye scheduled for cataract surgery using sterile swab stick and transported to medical laboratory for analysis. Susceptibility tests were carried out on the representatives of different groups of available antibiotics. Data was analyzed using the SPSS version 23. RESULT: The participants were mainly females (64.4%), married, and farmers, with at least primary school education and a mean age of 64 ± 2SD years. The conjunctival swab bacteria isolation rate was 36.5%. Gram-positive bacteria accounted for 73.7% of the total isolates. Coagulase-negative Staphylococcus (34.2%) was the most frequently isolated bacteria. Gentamicin, ofloxacin, and polymycin B (76%) were the most efficacious antibiotics followed by moxifloxacin and tobramycin (68%) on all the isolates. Ofloxacin (82%) was the most sensitive to Gram positive while gentamicin (90%) was for Gram-negative bacteria. CONCLUSION: In Enugu, the most common pre-operative conjunctival bacteria isolated were Coagulase-negative Staphylococcus with varied antibiotic sensitivity. Routine prophylaxis with gentamicin and ofloxacin is therefore advised to forestall the dreaded post-operative endophthalmitis.

Gastrointestinal Parasitic Infections and Immunological Status of HIV/AIDS Coinfected Individuals in Nigeria.

BACKGROUND: Parasitic infections of the gastrointestinal tract is one of the highest causes of morbidity and mortality among HIV infected individuals. This is due to the colonization of the intestinal tract by parasites influenced by induced enteropathy caused by HIV infection. CD+4 t-lymphocytes count is a marker of the immune status of HIV infected individuals. OBJECTIVE: This study investigated the prevalence of gastrointestinal parasitic infections among HIV coinfected individuals in relation to their immunological status. METHODS: CD+4 t-lymphocytes count was determined using fluorescence-activated cell sorting (FACS) count system. Parasitological examination of faecal samples was conducted using direct wet mount, modified Z-N and Giemsa stain techniques. All prepared slides were examined under x10 and x40 objectives. FINDINGS: Out of the 891 HIV seropositive participants on antiretroviral therapy that were studied, 641 (71.9%) had CD+4 counts equals to or greater than 500 cells/mm3. All other seropositive participants had CD+4 counts below 500 cells/mm3. Gastrointestinal parasitic infections were recorded in 187 (20.9%) seropositive participants, with females (n = 108, 12.1%) having more infections than males. Multiple gastrointestinal parasitic infections were recorded in 28 (3.1%) seropositive participants. Out of the 150 seronegative participants, 79 (52.7%) of them had at least one gastrointestinal parasitic infection. Female seronegative participants also accounted for higher infection rate (n = 42, 28.0%) than males (n = 37, 24.7%). Multiple infections were also recorded in 18 (12.0%) seronegative individuals. The overall prevalence rate of infection between both positive and negative individuals was 25.5%. There was statistical significant difference in the infections of Cryptosporidium parvum (p < 0.003), Cyclospora cayetanensis (p < 0.011) and Cystoisospora belli (p < 0.011) between HIV seropositive and HIV seronegative individuals. Also, there was statistical significant difference in the infections of hook worm (p < 0.002) and Trichuris trichiura (p < 0.020) between seronegative and seropositive individuals. Gastrointestinal parasitic infection rate was significantly higher among seropositive participants with CD+4 counts between 200 and 350 cells/mm3 (n = 109, 58.3%). CONCLUSION: The study shows that HIV infected individuals continue to experience gastrointestinal infections even with antiretroviral treatment, especially those with CD+4 counts below 350 cells/mm3. Health care providers should prioritise routine screening of HIV patients for gastrointestinal parasites and provide prompt treatment. Antiparasitic drugs should also be provided as prophylaxis.

Maternal vitamin A supplementation delays time to first episode of parasitaemia and reduces malaria parasite densities among infants in rural communities in Ebonyi State, Nigeria.

The study was a randomized mother -infant dyad placebo controlled field trial that evaluated the effect of maternal vitamin A supplementation on time to first episode of parasitaemia and on malaria parasite densities among infants in three rural communities in Ebonyi State, Nigeria. One hundred and fifty-two (152) pregnant women with pregnancies that had mature to at least six (6) months were equally randomized into supplemented and placebo groups. Ten thousand international unit (10,000 IU) of vitamin A supplement was administered three (3) times per week to women of the supplemented group while placebo was given to the control group at equal frequencies. The regimen was continued until the participants delivered their babies. On delivery of their babies, 200,000 1U of vitamin A supplement was administered to the supplemented group while the other group also received placebo. The regimen was maintained every three (3) month until the infants were 12 months old. Follow-up was carried out monthly and 3 ml of venous blood was collected quarterly from the infants and used for determination of parasitaemia. The procedure was carried out following standard parasitological techniques. Data collected were analysed using analysis of variance (ANOVA), Fisher's least significant difference (FLSD), and Ttest. Statistical significance was established at p<0.05. Infants of mothers from the placebo group were infected by malaria parasites at earlier months of their lives while their counterparts had parasitaemia much later. Malaria parasite densities significantly differed (p<0.05) among infants of the two groups, with infants of vitamin A supplemented women having lower parasite densities in comparison with their counterparts. Pre-partum and post- partum supplementation of vitamin A within the recommended dosages are required for improvement of nutritional status and well-being of both mothers and infants.

Maternal vitamin A supplementation delays time to first episode of parasitaemia and reduces malaria parasite densities among infants in rural communities in Ebonyi State, Nigeria

@#The study was a randomized mother –infant dyad placebo controlled field trial that evaluated the effect of maternal vitamin A supplementation on time to first episode of parasitaemia and on malaria parasite densities among infants in three rural communities in Ebonyi State, Nigeria. One hundred and fifty-two (152) pregnant women with pregnancies that had mature to at least six (6) months were equally randomized into supplemented and placebo groups. Ten thousand international unit (10,000 IU) of vitamin A supplement was administered three (3) times per week to women of the supplemented group while placebo was given to the control group at equal frequencies. The regimen was continued until the participants delivered their babies. On delivery of their babies, 200,000 1U of vitamin A supplement was administered to the supplemented group while the other group also received placebo. The regimen was maintained every three (3) month until the infants were 12 months old. Follow-up was carried out monthly and 3 ml of venous blood was collected quarterly from the infants and used for determination of parasitaemia. The procedure was carried out following standard parasitological techniques. Data collected were analysed using analysis of variance (ANOVA), Fisher’s least significant difference (FLSD), and Ttest. Statistical significance was established at p<0.05. Infants of mothers from the placebo group were infected by malaria parasites at earlier months of their lives while their counterparts had parasitaemia much later. Malaria parasite densities significantly differed (p<0.05) among infants of the two groups, with infants of vitamin A supplemented women having lower parasite densities in comparison with their counterparts. Pre-partum and post- partum supplementation of vitamin A within the recommended dosages are required for improvement of nutritional status and well-being of both mothers and infants.

Audit of ophthalmology discharge summaries in a Nigerian Teaching Hospital.

BACKGROUND: Discharge summaries are important components of hospital-care transitions in ensuring continuity of care. AIM: We assessed the adequacy and accuracy of discharge summaries written by junior doctors. METHODS: An instrument, adapted largely from the current hospital discharge summary template and recommendations regarding content from the Joint Commission International, was used to study 420 discharge summaries written in 2012 from the ophthalmology service of a Rural Teaching Hospital in Nigeria. The simple descriptive analysis was done with Statistical Package for the Social Science version 17. RESULTS: Completeness of entries was relatively high in many traditional areas (biodata of patient, admission/discharge dates, name of supervising consultant, principal diagnosis, surgical procedures done, follow-up instructions, and condition on discharge) of the summaries. The portion of the paper-based template titled "summary" of the admission was most problematic; with information on medication changes and result of tests missing in 368/420 (87.6%) and 334/420 (79.5%), respectively. CONCLUSION: Educational intervention for doctors in training with the provision of oversight and feedback by their supervisors is required. Standardized discharge summary templates recognizing the peculiarities of specialized patient groups are recommended. Transition to electronic discharge summary system is imperative.

Urinary schistosomiasis among pregnant women in some endemic tropical semi - urban communities of Anambra State, Nigeria.

Urinary schistosomiasis is caused by the deposition of eggs by adult flukes in the blood vessels surrounding the bladder of the infected host. Schistosomiasis is ranked the second most important parasitic disease of man and undoubtedly the most important of helminth origin. This paper reports the prevalence of Schistosoma haematobium infection among pregnant women in some endemic tropical semi - urban communities of Anambra State, Nigeria, screened using Medi-Test Combi 9 and urine centrifugation methods. Laboratory analysis of urine samples collected from 172 pregnant women indicated that 41 (23.8%) had urinary schistosomiasis with Anam community having the highest prevalence of 35.1% among other communities. The overall prevalence and intensity of infection among age groups showed that the youngest age group in the study, 16-20 years had the highest prevalence. Out of 24 women within this age group, 12 (50.0%) were infected among which 8 (33.3%) had light infection while 4 (16.6%) had moderate infection. The peak mean intensity of 7.6 eggs/10ml urine was observed in age group 16-20 years while the oldest age group, 41-45 years had the lowest mean intensity of 1.0 egg/10ml urine. Haematuria and proteinuria which are diagnostic for schistosomiasis were higher within age group 16-20 years in all the communities with Anam community having the highest prevalence of 50% for both biochemicals within age group 16-20 years. The findings from this study will be useful in developing specific programme for this special group of women.

Parasitological and histopathological effects of immunosuppression in guinea-pigs (Cavia porcellus) experimentally infected with Schistosoma haematobium.

The parasitological and histopathological effects of immunosuppression in guinea-pigs (Cavia porcellus) experimentally infected with Schistosoma haematobium were studied. A total of 16 guinea-pigs were divided into four groups (four per group): non-immunosuppressed, non-infected group (NN); immunosuppressed, non-infected group (IN); immunosuppressed, infected group (II); non-immunosuppressed, infected group (NI). The IN and II groups were immunosuppressed with 5 mg/kg prednisolone while the II and NI animals were infected with 200-300 S. haematobium cercariae. Excretion of eggs in urine/faeces, worm burden and histopathology of some vital organs of the guinea-pigs were studied. Eggs of S. haematobium were observed in the urine of the NI and II groups from 9 weeks post-infection and in faeces from 10 and 13 weeks post-infection for the NI and II groups, respectively. However, II animals excreted more viable eggs in urine and faeces than those of the NI group. Worm recovery at 14 weeks post-infection showed that NI and II guinea-pigs had more female worms than male worms and a greater proportion of worm recovery for NI animals was of immature worms. Significant differences (P < 0.05) existed between female, male and immature worm burden of the two groups but not in their total worm burden (P>0.05). Histological changes, which were notably reactions to adult S. haematobium worms, were observed in the organs of the NI and II groups but these changes were seen more in the organs of the immunosuppressed, infected (II) than in the non-immunosuppressed, infected (NI) guinea-pigs. The results suggest that immunosuppression before infection increased worm survival and had a moderate effect on liver and bladder histology of S. haematobium infected guinea-pigs.

Urinary schistosomiasis among pregnant women in some endemic tropical semi – urban communities of Anambra State, Nigeria

Urinary schistosomiasis is caused by the deposition of eggs by adult flukes in the blood vessels surrounding the bladder of the infected host. Schistosomiasis is ranked the second most important parasitic disease of man and undoubtedly the most important of helminth origin. This paper reports the prevalence of Schistosoma haematobium infection among pregnant women in some endemic tropical semi – urban communities of Anambra State, Nigeria, screened using Medi-Test Combi 9 and urine centrifugation methods. Laboratory analysis of urine samples collected from 172 pregnant women indicated that 41 (23.8%) had urinary schistosomiasis with Anam community having the highest prevalence of 35.1% among other communities. The overall prevalence and intensity of infection among age groups showed that the youngest age group in the study, 16-20 years had the highest prevalence. Out of 24 women within this age group, 12 (50.0%) were infected among which 8 (33.3%) had light infection while 4 (16.6%) had moderate infection. The peak mean intensity of 7.6 eggs/10ml urine was observed in age group 16-20 years while the oldest age group, 41-45 years had the lowest mean intensity of 1.0 egg/10ml urine. Haematuria and proteinuria which are diagnostic for schistosomiasis were higher within age group 16-20 years in all the communities with Anam community having the highest prevalence of 50% for both biochemicals within age group 16-20 years. The findings from this study will be useful in developing specific programme for this special group of women.

Pterygium: A review of clinical features and surgical treatment.

BACKGROUND: Ptergium is a frequently encountered clinical entity in ophthalmic practice. Although commoner in the tropics compared with the temperate region, all Ophthalmologists worldwide should be conversant with the clinical features and outcome of various approaches to surgical management. A review of the efficacy of the currently available surgical procedures for pterygium excision using postoperative recurrences as the main outcome measure is presented. METHOD: Manual and electronic (PUBMED, MEDLINE, AJOL AND HINARI) search for medical literature relevant to clinical features and surgical treatment of pterygium was conducted. Previous reviews, large case series reports, randomized controlled trials and one meta-analysis were selected and critically reviewed. RESULTS: Postoperative recurrence is a dominant complication of pterygium excision irrespective of the adopted surgical procedure. Pterygium excision with adjunctive therapy and ocular surface reconstruction is the current procedure of choice in view of its comparatively higher efficacy in preventing recurrence. CONCLUSION: Recurrence is the commonest postoperative complication of pterygium excision. There is need for further research into the aetiopathogenesis and risk factors for recurrence of human pterygia.

What does the medical student know about eye donation/corneal transplant? The University of Nigeria scenario.

OBJECTIVE: The study was designed to determine the knowledge of eye donation and corneal transplant among final year medical students of The University of Nigeria, Enugu Campus (UNEC). METHODS: Self-administered structured questionnaires were distributed to the members of the final year (graduating) class of the Medical College of UNEC in June 2007. Responses were obtained to questions bordering on eye donation and corneal transplant. RESULTS: One hundred and thirty-one students out of 183 eligible students participated in the study (response rate = 71.6%). One hundred and four students (79.4%) were aware of eye donation/corneal transplant. However 95 students (72.5%) were not aware that the eyes can only be removed from a dead donor. Eighty-four students (64.1%) were not aware that eyes with cataract could be donated. Eighty-seven (66.4%) students were not willing to pledge their eyes for donation. CONCLUSION: Medical students lack adequate knowledge about some aspects of eye donation and corneal transplantation. This may be a predictor of the level of awareness among the general public. Concerted innovative education and information dissemination strategies are required at this stage of national development to address the misconceptions surrounding eye donation and corneal transplant. There is a need to target medical students as future motivators, counsellors and eye donors. This should help advance the eye donation rates in Nigeria whenever the plans for the establishment of an eye-bank are finalized.

Ocular Features Seen in Children with Hydrocephalus at University of Nigeria Teaching Hospital Enugu: A Case Series

Background:Hydrocephalus has been known since antiquity. It has been defined as an increase in size of the ventricular system of the brain; resulting from raised cerebrospinal fluid volume. Objective: The purpose of this study is to determine the various ocular disorders that may be associated with hydrocephalus in children seen in the University of Nigeria Teaching Hospital (UNTH) Enugu.Patients and Methods: This study was carried out on 15 patients attending the neurosurgical outpatient clinic of the University of Nigeria Teaching Hospital Enugu. All patients who met the criteria for inclusion in the study of hydrocephalus; aged less than two years and attended the neurosurgical outpatient clinic between January and December 1998 were included. The diagnosis of hydrocephalus was made based on the history; clinical examination and brain ultrasonography. The data was analysed with a scientific calculator Casio FX-82 Lb and Epi info version 6 software.Results: Fifteen children with un-operated hydrocephalus confirmed by transfontanelle ultrasonography were examined at presentation for ocular complications of hydrocephalus. The mean age at presentation was 29.8 weeks. The peak age group of presentation was 11-20 weeks. The male/female ratio was 1:1. Ocular complications of hydrocephalus included setting sun appearance; nystagmus; optic disc palor and hyperaemia. Conclusion: The Ophthalmologist has a well established role to play in assisting the paediatric neurosurgeon in the long term management of children with hydrocephalus if the risk of blindness is not to be added to their other physical disabilities

Myopia: a review of literature.

INTRODUCTION: Among the refractive errors, myopia is a leading cause of visual impairment throughout the world and its prevalence is on the increase. Pathological myopia is a genetically determined refractive error and a growing body of evidence shows that visual experiences early in life may affect ocular growth and eventual refractive error. In addition to the human cost of visual debility, there is a profound economic cost to the society. The current review highlights recent advances in the management of myopia. METHODS: Information was obtained by searching Medline for citations of articles in English using the Keyword "Myopia" in addition to current literature review. RESULT: Myopia can be classified into two groups, low to moderate degree of myopia (refered to as simple myopia-0.5 to -6.0 dioptres) and high or pathological myopia (greater than 6.0 dioptres). Simple myopia can be corrected with spectacles or contact lenses whereas high myopia may be complicated by potentially blinding conditions such as vitreous and macular degeneration and retinal detachment. CONCLUSION: Recent advances in the management of myopia have made it possible to restore vision to a reasonable degree.

The Undergraduate Training in Ophthalmology: The University of Nigeria Nsukka Medical Students

Objective: The study was embarked upon to determine the view of University of Nigeria final year medical students on the adequacy of their undergraduate training in ophthal- mology; vis-a-vis rendering basic eye care as general duty doctors. Methods: One hundred final year medical students; who had finished their ophthalmology clinical postings; completed a self-administered; structured and semi structured questionnaires in August 2004. Data analysis was done manually using an electronic calculator. Result: Majority of the students (60) were of the view that the training was inadequate. This was largely attributed to the low level of clinical exposure and community experience in the programme. Conclusion: The undergraduate training in ophthalmology undergone by these final year medical students may not have equipped them with adequate knowledge and skills to render basic eye care as general duty doctors. There is a need to improve the relevance and quality of the training.) were of the view that the training was inadequate. This was largely attributed to the low level of clinical exposure and community experience in the programme. Conclusion: The undergraduate training in ophthalmology undergone by these final year medical students may not have equipped them with adequate knowledge and skills to render basic eye care as general duty doctors. There is a need to improve the relevance and quality of the training

Investigation into the prevalence of urinary schistosomiasis in the Agulu Lake area of Anambra State, Nigeria.

In epidemiological surveys for urinary schistosomiasis caused by Schistosoma haematobium in communities around Agulu Lake, Anambra State, Nigeria, between 1990 and 1992, the infection was found to be endemic in the area, especially in three towns: Nri, Agulu, and Adazi Nnukwu. The prevalence rates varied between these communities and with the year. Inter-town prevalence rates ranged from 5.96% to 54.00%. Intravillage prevalence rates ranged between 5.50% to 96.43%. Prevalence rates were highest in villages very close to Agulu lake. There was no significant difference in prevalence between the schools. Host age, but not sex, was found to play a significant role in prevalence and intensity of infection. There was also a strong correlation between visible haematuria and egg count per 10 ml urine, but eggs could be isolated in urine samples of different shades of coloration. Analysis of incidence of infection in these communities shows that Schistosoma haematobium incidence is high in Nri (55.17%) and low at Adazi Nnukwu (5.26%). Both Bulinus globosus and B. truncatus were found in the lake and both shed mammalian bifid schistosome cercariae.

Schistosoma haematobium cercariae transmission patterns in freshwater systems of Anambra State, Nigeria.

The seasonality of infection of Bulinus (Ph.) globosus, the snail host of Schistosoma haematobium is reported. The pattern of snail infection was shown to vary with the type of habitats. The cercarial "transmission potential" was calculated based on the number of infected snails and the level of cercarial production. It is consequently assumed that the transmission pattern varies with season and habitat type. Dry season transmission potential was found to be high in running water habitats while low in stagnant water habitats. In the wet season, the reverse seems to be the case. The implication of these observations in the epidemiology of urinary schistosomiasis and in planning its control in the area is discussed.

On the effects of ivermectin on freshwater snails of medical and veterinary importance.

Ivermectin is lethal to Bulinus (Physopsis) globosus, Biomphalaria pfeifferi, and Lymnaea natalensis at concentrations of 0.08 micrograms/ml and above. Studies show that these snails will not recover from a 24 h exposure to 2.00 micrograms/ml of Ivermectin in the laboratory at 28 +/- 2 degrees C. A time dependent toxicity to snails was recorded and an exposure of adult snails to sub lethal concentrations significantly reduced the number of eggs laid (r = -0.08, t = 2.64, P less than 0.05).

Distribution of freshwater gastropods in the lower River Niger and Cross River basins of southeastern Nigeria with reference to their trematode infections.

Malacological surveys on the abundance of molluscan fauna were carried out in freshwater habitats at the 2 main rivers of southeastern Nigeria: River Niger and Cross River basins. A total of 19 species of gastropods were found, 13 of which are pulmonates and 6 prosobranchs. The distribution of the species varied between the habitats, with high densities recorded in patches within the habitats. Infected snails were collected mainly from portions of the habitats that are accessible. Trematode cercariae types and infection rates were recorded for each snail species. Seasonal patterns of both snail types and their trematode infection at various developmental stages are discussed.