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Biomedical subjects

A Abiose

Publications and source records attributed to A Abiose.

At least 19 recordsLinked to original sources
PubMed2005

The problem of trachoma within an onchocerciasis-endemic zone in Kaduna: need for a multilateral approach?

INTRODUCTION: Within the mesoendemic onchocerciasis belt of Kaduna State, Northern Nigeria, there were other causes of ocular morbidity as well. We investigated the contribution of trachoma. METHODS: A total of 6831 individuals were examined for eye disease, including signs of trachoma. RESULTS: The overall prevalence of trachoma was 4.5% (577 eyes of 310 individuals), making it the second most common cause (1 in 5) of ocular morbidity after cataracts. Of the 577 eyes, 405 (70.2%) had cicatrizing disease while the rest had active disease. Overall, the prevalence of TF was 1.1% (1.3% in those < 10 years of age), TI 0.2%, TS 3%, CO 0.5% and TT 1.1% (4.3% and 3.5% in subjects aged > 55 and > 40 years, respectively). The prevalence of trachoma increased with age. The overall prevalence of blindness in the whole population was 2.7%. Trachoma accounted for 11% of this. On the other hand, onchocerciasis accounted for 3.1% of the overall ocular morbidity (less than trachoma) and 39% of the blindness. CONCLUSIONS: There appears to be a clear need to retrain middle cadre ivermectin workers in trachoma rapid assessment and SAFE strategy intervention methods in order to further impact blindness prevention in these 'onchocerciasis-endemic' zones.

Adolescent↗
PubMed2005

The rapid monitoring of ivermectin treatment: will school-based surveys provide the answer?

The data on ivermectin-treatment coverage recorded in household surveys sometimes conflict with those recorded in school-based surveys or in the relevant treatment registers maintained by community-directed distributors (CDD). An attempt has now been made, in two sites in Nigeria (Enugu and Kaduna states) and one in Sudan (Abu Hamad province), to determine how well these three sets of data are correlated (and to explore the effectiveness of several alternative channels for the delivery of treatment-monitoring forms to schools). Using a cross-sectional approach, data were collected from primary schools, households and treatment registers. Calculation of Pearson's correlation coefficients (r) indicated that, overall, the data from the household surveys were very similar to those collected using the school-based strategy (r=0.66; P<0.0001) or from the treatment registers of the CDD (r=0.86; P<0.0001). The information recorded in the CDD registers also closely matched that recorded in the school-based surveys (r=0.67; P<0.0001). These encouraging results for the pooled data masked some inter-site differences. The correlation between the household-survey and treatment-register data was, for example, only good in Enugu (r=0.89; P<0.001), and was too weak to be statistically significant in Abu Hamad or Kaduna. Although the results of the school-based survey in Kaduna also did not closely correlate with those of the corresponding household survey (r=0.10; P=0.71), the household survey at this site was probably not conducted as well as those at the two other sites. In general, it appears that school-based surveys are an effective means of monitoring community coverage with ivermectin, rapidly, accurately and at relatively low cost. It is therefore recommended that school-based methods of monitoring of coverage are adopted by programme managers.

Child↗
PubMed2003

Blindness: how to assess numbers and causes?

BACKGROUND: Traditionally, blindness surveys have modelled themselves on the "gold standard" of a census and examination of a whole population. Blindness, however, is a relatively rare condition even in badly affected communities; hence, large sample sizes are required to gain adequate estimates of prevalence, particularly by cause. METHODS: Three assessments of blindness prevalence and aetiology in the same communities are reported. One involved asking individuals questions concerning their visual status during a census (perceived visual status, PVD), one involved examination of all ostensibly visually disabled people presenting to a central point within each community (examination of the visually disabled, EVD), and the final assessment involved a gold standard examination of the whole population (whole community examination, WCE). RESULTS: In a population of 8139 the blindness prevalence was 2.7% PVS, 3.6% EVD, and 3.1% WCE. Attributed causes of blindness were not representative in the PVS except for cataract. The END yielded cause specific estimates not far from those found at WE except for a relative under-representation of glaucoma and optic atrophy. CONCLUSION: Since cataract is, by a significant margin, the most common cause of blindness in the world such a simple method as asking individuals if they are blind and what they believe to be the cause may yield adequate estimates of the problem for planning eye care strategies for this condition. Alternatively, an ophthalmologist visiting villages and examining allcomers for visual disability may provide reasonably accurate cause specific prevalence estimates without the expense of a major blindness survey.

Adolescent↗
PubMed2001

Intraocular pressure and gonioscopic findings in rural communities mesoendemic and nonendemic for onchoceriasis, Kaduna State, Nigeria.

PURPOSE: To report on glaucoma-related ocular parameters, namely intraocular pressure and peripheral anterior synechiae, in the presence of onchocercal infection. METHODS: Two computer-generated random samples of individuals were drawn from communities mesoendemic and nonendemic for onchocerciasis respectively. Applanation tonometry and gonioscopy were carried out on these individuals. RESULTS: Four hundred and thirty-six and 319 individuals from the mesoendemic and nonendemic communities were examined respectively. The mean intraocular pressure was 1.58 mmHg lower in the individuals from the mesoendemic communities compared with those from the nonendemic communities (p < 0.001) despite the prevalence of peripheral anterior synechiae being higher in the mesoendemic communities. In these communities, there was strong evidence that the prevalence of peripheral anterior synechiae increased with increasing microfilarial load. CONCLUSIONS: Onchocercal infection produces a low-grade inflammatory process, which may result in a lowering of intraocular pressure despite the formation of peripheral anterior synechiae. Glaucomatous optic nerve damage may therefore not be the primary cause of visual loss in ocular onchocerciasis as this occurs late and is probably preceded by other blinding onchocercal pathology.

Adolescent↗
PubMed2001

Magnitude of trachoma and barriers to uptake of lid surgery in a rural community of northern Nigeria.

AIMS: A population-based cross-sectional survey for trachoma prevalence was conducted in a subdistrict of northern Nigeria. The objectives of the survey were to determine the magnitude and pattern of trachoma and the barriers to uptake of lid surgery in the area. METHODS: A total of 2903 people of all ages were examined out of 3715 registered eligible persons. The study population was chosen by a two-stage cluster random sampling technique. Each person was examined for signs of trachoma. The World Health Organization (WHO) simplified trachoma grading was used. Persons with trichiasis that had not attended hospital were asked why they had not sought hospital treatment. RESULTS: A blindness prevalence of 1.5% (95% CI 0.4%-2.7%) was found in the study population. About 20% of the blindness were due to trachoma. The prevalence of trichiasis among women 15 years and above was found to be 8.6% (95% CI 6.8%-10.7%). The prevalence of active trachoma among children was 11.8% (95% CI 10.1%-13.3%). Over 90% of people with trichiasis have not sought medical attention. The major identified factor that prevents people from accessing hospital treatment for trichiasis was cost (57%). CONCLUSION: This study suggests that trachoma is of public health significance in this area; as such, an effective trachoma control program with emphasis on lid surgery should be established.

Adolescent↗
PubMed2001

Trial of Trachoma Rapid Assessment in a subdistrict of northern Nigeria.

PURPOSE: To assess the usefulness of Trachoma Rapid Assessment (RA) in priority ranking of trachoma areas. METHODS: RA was conducted concurrently with a cross-sectional trachoma prevalence survey in some villages selected from the communities at risk for trachoma in the Kaita Local Government Area of northern Nigeria. The RA team consisted of two ophthalmic nurses. Pen torches and loupes were used for the examination. Data were collected on the seven components of the RA 'information pyramid' for all the selected villages. The data were analyzed using the RA methodology guidelines to determine the priority villages for trachoma intervention. This was compared with the ranking from the cross-sectional trachoma prevalence survey. RESULTS: The results of RA were found to be in agreement with the cross-sectional survey in 53.3% of the villages in the priority ranking of trichiasis, while in the priority ranking of active trachoma the agreement between the two methods was found to be 60%. The risk factors for trachoma were shown to be of high magnitude in all the villages using both the RA method and the prevalence survey. CONCLUSION: RA may be a more useful tool when applied to a vast area where the risk of trachoma is likely to differ greatly between different parts of the area. In the determination of the trichiasis pattern of a community by RA, it may be more useful to use the actual number of trichiasis cases in the area rather than the prevalence of trichiasis. The operational definition of some risk factor indicators seems very subjective and vague. The RA method needs more validation to sharpen the indicators used.

Adult↗
PubMed2001

Glaucoma prevalence may not be uniformly high in all 'black' populations.

Epidemiological data on the prevalence of glaucoma are generally presented for populations described as "whites" or "blacks". "Black" populations appear to have a higher glaucoma preva lence than "white" populations. We describe a population-baseed survey for glaucoma in rural Northern Nigeria. A total of 1563 Hausa/Fulani individuals aged 5 years and above, underwent an extensive screening test and a detailed ophthalmological examination was performed on individuals who failed the test. The overall prevalence of open angle glaucoma in this population was 1.02% (0.12 to 3.64, 95% confidence interval) in individuals 45 years of age and older. This is lower than the prevalence rates reported for other "black" populations. The low prevalence of glaucoma detected in this African population may be, to some extent, a reflection of the age structure of the population studied or methodological differences in ophthalmic examinations performed. It is also possible that the prevalence of glaucoma varies considerably between "black" populations due to genetic heterogeneity or the effect of some unidentified environmental exposure. The use of the simple description of populations as 'black' (or 'white'), which focuses on a commonality, tends to obscure the potential heterogeneity within and between populations and thus may be unhelpful in some circumstances.

Adolescent↗
PubMed2000

Audit of outcome of an extracapsular cataract extraction and posterior chamber intraocular lens training course.

BACKGROUND: A training course for cataract surgery with intraocular lens implantation was organised in April 1997 at the National Eye Centre, Kaduna, Nigeria. Operations were performed by six Nigerian consultant ophthalmologists under the supervision of two surgeons from Aravind Eye Hospital, India. METHODS: A total of 175 eyes with uncomplicated cataracts were operated on after careful selection. All but six patients had extracapsular cataract extraction with posterior chamber intraocular lens insertion during the training programme. RESULTS: The mean age of the patients at operation was 54. 2 years. One hundred and forty five of the operated eyes (85.8%) were blind before surgery of which six (3.6%) remained blind postoperatively. An uncorrected visual acuity of 6/60 or better was achieved in 87.3% eyes after surgery. Forty one patients (24.3%) were blind before surgery, two of whom (1.2%) remained blind afterwards. The most common intraoperative complication was posterior capsular rent which occurred in 10 eyes (5.7%); striate keratopathy/corneal oedema and cortical remnant were the most common immediate postoperative complications, occurring in 44.6% and 8.0%, respectively. CONCLUSION: With adequate surgical skills, extracapsular cataract extraction with posterior chamber intraocular lens implantation offers good visual rehabilitation even under training conditions.

Adult↗
PubMed1998

Onchocercal eye disease and the impact of Mectizan treatment.

Onchocerciasis continues to be a major cause of blindness, particularly in those sub-Saharan African countries which are outside the area of West Africa monitored by the Onchocerciasis Control Programme (OCP). Onchocercal ocular disease and blindness develop as a result of long exposure to onchocercal infection. Until 1987, suramin and diethylcarbamazine were the only drugs available for the treatment of onchocerciasis and they could not be used for community therapy because of their toxicity and the dosage schedules required. The registration of Mectizan (ivermectin, MSD) for treatment of human onchocerciasis in 1987, and the donation of this drug by Merck & Co. for as long as it is needed, provided a new opportunity for the safe treatment and control of the disease. The data available on the impact of repeated doses of Mectizan on ocular onchocercal disease indicate a significant reduction of ocular microfilarial loads and regression of early lesions of the anterior segment, including iridocyclitis and sclerosing keratitis. Such improvements are seen more rapidly when Mectizan is used than when onchocerciasis is limited by vector control alone. Mectizan treatment also has a beneficial effect on onchocercal optic-nerve disease and visual-field loss. Long-term maintenance of Mectizan therapy should lead to a reduction in the prevalence of blindness in endemic communities.

Africa↗
PubMed1998

Blue-yellow colour vision in an onchocercal area of northern Nigeria.

AIM: To determine if the City University Tritan Test is a useful addition to visual function assessment in rural communities in northern Nigeria. METHODS: The study was a cross sectional survey. The participants were 8394 people, aged 5 years and over, living in 37 rural communities, mesoendemic and nonendemic for onchocerciasis, in Kaduna State in northern Nigeria. The main outcome measures were the detection of a defect in blue-yellow colour vision by two criteria: (1) failure with the City University tritan screening plates; (2) failure with the City University grading plates to identify severe tritan defects. RESULTS: 91% of those aged 10 years and above could perform the test. Below this age, there were difficulties in comprehension. The test showed good inter- and intraobserver agreement. After adjustment for confounders the odds of failing the screening plates were significantly increased in the presence of optic atrophy or glaucoma (3.55 (2.48-5.08) and 15.9 (4.22-60.2) respectively). There was a greater increase in the adjusted odds of failing the grading plates in the presence of optic atrophy or glaucoma (5.30 (2.97-9.45) and 8.87 (1.61-48.7) respectively). Cataract had a smaller effect on the screening plates, adjusted odds 1.63 (0.95-2.80). CONCLUSION: Blue-yellow colour vision testing is a useful addition to visual function assessment in those aged 10 years and above in rural northern Nigeria, particularly in the detection of optic nerve disease.

Adolescent↗
PubMed1997

HLA-DQ alleles associate with cutaneous features of onchocerciasis. The Kaduna-London-Manchester Collaboration for Research on Onchocerciasis.

Onchocerciasis is associated with a spectrum of cutaneous changes, ranging from clinically normal skin to acute and chronic pathology. An important aspect of disease expression may be the level of immune response to parasite antigens, which is likely to be regulated by MHC-encoded molecules. We therefore investigated HLA class I and class II phenotypes in Nigerian residents of an area endemic for onchocerciasis. All study subjects were carefully characterized for parasite load and skin pathology. Individuals with depigmentation had increased frequencies of DQA1*0501 and DQB1*0301 compared with persons with normal skin and high microfilarial load (NSHMF) (Odds Ratios 3.6 (95% CI 1.0 to 13.2) and 3.8 (1.0 to 15.2), respectively). Conversely, individuals with depigmentation had a decreased frequency of DQA1*0101 and Cw6 compared with NSHMF (Odds Ratios 0.2 (0.1 to 0.9) and 0.1 (0.02 to 0.8), respectively). When NSHMF subjects were examined by age, a further decrease in DQA1*0501 frequency and increase in DQA1*0101 frequency were observed in older NSHMF individuals. These results strongly suggest that there is an immunogenetic basis for the spectrum of cutaneous presentations in onchocerciasis and that HLA-DQ molecules are associated with the level of immune response to parasite antigens.

Adolescent↗
PubMed1997

Risk factors for optic nerve disease in communities mesoendemic for savannah onchocerciasis, Kaduna State, Nigeria.

Ophthalmic examinations on 6831 individuals aged 5 years or more, living in 34 guinea savannah communities mesoendemic for onchocerciasis, in Kaduna State, Nigeria, revealed a relatively high prevalence (9%) of optic nerve disease (OND). Further investigations were performed to determine what proportion of this burden of OND might be due to onchocercal infection. Information on history of cerebro-spinal meningitis (CSM), past use of diethylcarbamazine (DEC) and chloroquine, consumption of cassava and locally produced alcohol was collected for all individuals by questioning. In addition, a nested case-control study of 81 cases of OND and 136 age and sex-matched controls was performed to investigate whether syphilis or a variety of other neurological disorders were responsible for a substantial proportion of cases of OND. Our data suggest that in this population, onchocercal infection is the single most important cause of OND and may account for 50% of all cases. Some 13% of cases were associated with signs suggestive of glaucoma. DEC use might be responsible for up to 30% of all OND. We found no evidence to suggest that any of the following are important causes of OND in the communities studied: CSM, syphilis, neurological syndromes such as polyneuropathy or other generalized neurological disease, consumption of raw cassava, consumption of locally prepared alcohol.

Adolescent↗
PubMed1997

Visual field constriction as a cause of blindness or visual impairment.

Reported are the results of a study of onchocerciasis in communities mesoendemic for savanna onchocerciasis in Kaduna State, northern Nigeria. The study involved 6831 individuals aged > or = 5 years who underwent an extensive screening examination for visual function including Friedmann field analysis. A total of 185 (2.7%) were bilaterally blind by acuity and an additional 28 (0.4%) were blind by visual field constriction. Also 118 (1.7%) individuals were visually impaired by acuity criteria. No criteria for visual impairment by field constriction have been established, and we therefore investigated three potential criteria. As a result, a further 60 (0.9%) individuals were identified with significant visual impairment due to field loss by the various definitions. Small islands of remaining peripheral field occurred in 50 individuals, while 40 individuals had marked reduction of binocular visual field below the horizontal meridian. Concentric visual field constriction to < 20 degrees was found in seven individuals. The WHO definition of blindness currently includes visual field damage criteria for blindness but not for visual impairment. Visual field loss is recognized as a major disability. We hope that these findings stimulate international discussion leading to the development of satisfactory definitions for visual impairment by visual field constriction.

Adolescent↗
PubMed1997

Impact of annual dosing with ivermectin on progression of onchocercal visual field loss.

Reported are the results of a randomized, double-masked, placebo-controlled trial of annual ivermectin dosing in 34 rural communities, Kaduna State, northern Nigeria, where guinea savanna onchocerciasis is mesoendemic. A total of 939 individuals underwent Friedmann field analysis at the first examination and saw at least 19 spots in at least one eye. Of these, 636 (68%) completed a subsequent Friedmann field analysis 2-3 years later. The adjusted incidence rate ratio for the ivermectin group versus the placebo group was 0.64 (95% confidence interval (CI): 0.42-0.98). There was some evidence that the impact of ivermectin was greatest among those who had received one dose of ivermectin. The majority of the deteriorations occurred in eyes that gave evidence of optic atrophy at the first examination. An analysis restricted to individuals with optic atrophy at baseline indicated a reduction of 45% in the incidence of visual field deterioration in the ivermectin group (95% CI: 8-67%). Previous findings have shown that ivermectin has an impact on the incidence of optic atrophy. Our results indicate, for the first time, that ivermectin has a substantial impact on the progression of visual field loss among those with pre-existing optic atrophy.

Adolescent↗
PubMed1996

Morphine-induced venodilation in humans.

Morphine has been extensively used in the treatment of pulmonary edema, and its action is believed to be mediated in part by its ability to produce peripheral venodilation. This study investigated whether opiates produce venodilation in human hand veins and explored the underlying mechanism(s). Fifteen healthy volunteers (11 men and four women) were studied with use of the dorsal hand vein compliance technique. After preconstriction with the selective alpha 1-adrenergic receptor agonist phenylephrine, dose-response curves were constructed to (1) opiate receptor agonists morphine (1 to 30 micrograms/min) or fentanyl (0.07 to 1 microgram/min), (2) a combination of morphine and the mu-opiate receptor antagonist naloxone, and (3) morphine and a combination of histamine (H1 and H2) receptor antagonists. Infusion of morphine caused venodilation in a dose-dependent manner, whereas fentanyl did not produce venodilation. Coinfusion of naloxone and morphine impaired the venodilation only slightly. Coinfusion of the H1- and H2-antagonists completely abolished the venodilatory effect of morphine. These results suggest that the venodilatory effect of morphine is mediated through histamine release and that mu-opiate receptors have little or no involvement in this process.

Adult↗
PubMed1996

Maintaining compliance to ivermectin in communities in two West African countries.

We have investigated various aspects related to managing wide-scale ivermectin distribution schemes within randomized controlled trials in communities where onchocerciasis is endemic. Multiple logistic regression analysis of determinants of compliance to five doses of ivermectin in 589 people in Sierra Leone showed independent significant associations with leopard skin depigmentation, the severity of side effects of treatment, fulfilling the exclusion criteria for treatment, and long-term residence in the community. These results are useful for tailoring health promotion messages in Sierra Leone, but the associations may differ in other West African societies. In Nigeria 1847 people were interviewed about various subjective responses, including itching. None of these showed clear improvement after three years of ivermectin treatment. Positive comments about treatment were generally non-specific and similar in the placebo and ivermectin groups. Negative comments were usually related to adverse reactions, especially itching and rash, and were more common after ivermectin. The lack of any benefit attributable to ivermectin that is discernible to its recipients may make it difficult to maintain the high compliance rates needed for long periods if mass dosing programmes are to have a lasting impact on onchocerciasis. In addition, no consistent effects of ivermectin were found by measuring visual acuity, height, weight or haematocrit in comparison with placebo. This may indicate that evidence of clinical impact is very slow to develop and is hard to measure using simple objective methods after only three doses of treatment. At present it seems that parasitological, entomological and detailed ophthalmological or dermatological methods are required to demonstrate the impact of ivermectin treatment in the medium-term.

Adolescent↗