Sensitivity and specificity of two glaucoma case-finding strategies for optometrists

Current best practice for primary open-angle glaucoma case-finding comprises history-taking, disc examination, intraocular pressure measurement and suprathreshold visual field analysis (SVFA). An alternative case-finding technique was formulated replacing SVFA with computerised quantitative disc assessment, using the Heidelberg retinal tomograph II (HRT II). Each approach was adopted by four optometrists who screened 29 POAG and 37 normal patients. Average sensitivities and specificities were similar in the two groups [sensitivity 71% (SVFA) vs 69% (HRT II); specificity 94% both groups]. Our inclusion of pre-perimetric glaucoma cases limited the sensitivity of the optometrists in this study. There was evidence to suggest that the optometrists tended to miss early changes at the optic disc such as disc haemorrhage, nerve fibre layer defects and subtle neuroretinal thinning.

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.

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.

Geographical distribution of variant Creutzfeldt-Jakob disease in Great Britain, 1994-2000

BACKGROUND

Geographical variation in the distribution of variant Creutzfeldt-Jakob disease (vCJD) might indicate the transmission route of the infectious agent to man. We investigated whether regional incidences of vCJD were correlated with regional dietary data.

METHODS

The National CJD Surveillance Unit prospectively identified 84 people with vCJD up to Nov 10, 2000, in Great Britain. Their lifetime residential histories were obtained by interviews with a close relative. Cumulative incidences of vCJD by standard region were calculated. Grid references for places of residence in 1991 were identified and evidence of geographical clusters were sought. Data on diet in the 1980s were analysed for regional correlations with vCJD incidence. The socioeconomic status of the places of residence of people with vCJD was compared with that of the general population.

FINDINGS

vCJD incidence was higher in the north of Great Britain than the south. The rate ratio (north vs south) was 1.94 (95% CI 1.27-2.98). The mean Carstairs' deprivation score for areas of residence of people with vCJD was -0.09 (-0.73 to 0.55), which is close to the national average of zero. Regional rates of vCJD were correlated with consumption of other meat or meat products as classified and recorded by the Household Food Consumption and Expenditure Survey (r=0.72), but not with data from the Dietary and Nutritional Survey of British Adults. Five people with vCJD in Leicestershire formed a cluster (p=0.004).

INTERPRETATION

Regional differences in vCJD incidence are unlikely to be due to ascertainment bias. We had difficulty determining whether regional variations in diet might cause these differences, since the results of dietary analyses were inconsistent.

Evidence of behaviour change following a hygiene promotion programme in Burkina Faso

OBJECTIVES

To determine whether a large, 3-year hygiene promotion programme in Bobo-Dioulasso, Burkina Faso, was effective in changing behaviours associated with the spread of diarrhoeal diseases. The programme was tailored to local customs, targeted specific types of behaviour, built on existing motivation for hygiene, and used locally appropriate channels of communication.

METHODS

Two population surveys recorded the coverage of the programme among target audiences (mothers of children aged 0-35 months). Four surveys were carried out: three prior to the programme and one in 1998 (after the programme had been running for 3 years), using structured observation of hygiene behaviours in the participants' homes to document changes in target behaviours.

FINDINGS

After the programme had run for 3 years, three-quarters of the mothers targeted had had contact with programme activities. Half could cite the two main messages of the programme correctly. Although the safe disposal of children's stools changed little between 1995 and 1998 (80% pre-intervention, 84% post-intervention), hand-washing with soap after cleaning a child's bottom rose from 13% to 31%. The proportion of mothers who washed their hands with soap after using the latrine increased from 1% to 17%.

CONCLUSION

Hygiene promotion programmes can change behaviour and are more likely to be effective if they are built on local research and use locally appropriate channels of communication repeatedly and for an extended time.

Efficacy of oral azithromycin versus topical tetracycline in mass treatment of endemic trachoma

OBJECTIVE

To compare the impact of mass treatment with oral azithromycin and topical tetracycline on the prevalence of active trachoma.

METHODS

A total of 1803 inhabitants from 106 households of eight Gambian villages were randomized, in pairs, to receive either three doses of azithromycin at weekly intervals, or daily topical tetracycline over 6 weeks. Ocular examinations were conducted before treatment, and 2, 6 and 12 months after treatment.

FINDINGS

Prior to treatment, 16% of the study participants had active trachoma. Two months after treatment, the prevalence of trachoma was 4.6% and 5.1% in the azithromycin and the tetracycline groups, respectively (adjusted odds ratio (OR) = 1.09; 95% confidence interval (CI) = 0.53, 2.02). Subsequently, the prevalence rose to 16% in the tetracycline group, while remaining at 7.7% in the azithromycin group (adjusted OR at 12 months = 0.52; 95% CI = 0.34, 0.80). At 12 months post-treatment, there were fewer new prevalent cases in the azithromycin group, and trachoma resolution was significantly better for this group (adjusted OR = 2.02; 95% CI = 1.42, 3.50).

CONCLUSION

Oral azithromycin therefore appears to offer a means for controlling blinding trachoma. It is easy to administer and higher coverages may be possible than have been achieved hitherto.

The pulvinar sign on magnetic resonance imaging in variant Creutzfeldt-Jakob disease

BACKGROUND

There is a need for an accurate non-invasive diagnostic test for variant Creutzfeldt-Jakob disease (vCJD). We investigated the sensitivity and specificity of bilateral pulvinar high signal on magnetic resonance imaging (MRI) for the diagnosis of vCJD.

METHODS

MRI from patients with vCJD and controls (patients with suspected CJD) were analysed. Scans were reviewed on two separate occasions by two neuroradiologists and scored for the distribution of changes, and likely final diagnosis. Scans from vCJD cases were reassessed to reach a consensus on all abnormalities.

FINDINGS

We analysed 36 patients and 57 controls. vCJD patients were correctly identified based on bilateral pulvinar high signal in 29 of 36 and 32 of 36 cases on the first assessment by the two radiologists, and 32 of 36 and 31 of 36 on their second assessment. Bilateral increased pulvinar signal was identified in one of 57 and one of 57 controls on the first assessment and two of 57 and three of 57 controls on the second assessment. These reported changes in controls were graded as minimal/equivocal in six of seven patients and moderate in one (<0.5% of all control assessments). 80% of the assessments in vCJD cases were graded as moderate or substantial. On consensus review, 28 of 36 cases and none of 57 controls had prominent bilateral pulvinar signal-sensitivity 78% (95% CI 60-90%) and specificity 100% (95% CI 94-100%). Other common MRI features of vCJD were medial thalamic and periaqueductal grey matter high signal, and the notable absence of cerebral atrophy. Pulvinar high signal correlated with histological gliosis.

INTERPRETATION

In the appropriate clinical context the MRI identification of bilaterally increased pulvinar signal is a useful non-invasive test for the diagnosis of vCJD.

Using serial registered brain magnetic resonance imaging to measure disease progression in Alzheimer disease: power calculations and estimates of sample size to detect treatment effects

OBJECTIVE

To evaluate the rate of brain atrophy calculated from serial magnetic resonance imaging (MRI) registration as a surrogate marker of disease progression for use in clinical trials in Alzheimer disease (AD).

METHODS

Eighteen patients with mild to moderate AD and 18 age-matched normal controls underwent 2 MRI brain scans separated by a 12-month interval. Each individual's later scan was registered to their first scan, and the volume of cerebral tissue loss calculated directly from the registered and subtracted MRI scan pairs. The mean and SD of the rate of brain volume changes were used to estimate the sample sizes that would be needed in a clinical trial with a drug anticipated to modify disease progression by varying degrees. Comparable sample size estimates were performed with data for other methods of monitoring rates of brain atrophy, extracted from published papers.

RESULTS

The mean (SD) rate of brain atrophy for the patients with AD was 2.37% (1.11%) per year, while in the control group it was 0.41% (0.47%) per year. Based on these figures, to have 90% power to detect a drug effect equivalent to a 20% reduction in the rate of atrophy, 207 patients would be needed in each treatment arm. This assumes a 1-year placebo-controlled trial with a 10% patient dropout rate, and that 10% of scan pairs are unusable.

CONCLUSION

Registration of serial MRI volume images provides a powerful method of quantification of brain atrophy that can be used to monitor progression of AD in clinical trials.

Epidemic of fatal encephalopathy in preschool children in Burkina Faso and consumption of unripe ackee (Blighia sapida) fruit

BACKGROUND

On March 21, 1998, the Regional Health Authority of Bobo-Dioulasso, Burkina Faso, asked the Centre Muraz to investigate an unexplained outbreak of epidemic fatal encephalopathy (EFE). We aimed to identify the cause of this epidemic.

METHODS

We identified cases retrospectively through review of health-service records and interviews of family members, village chiefs, and local healers. Active surveillance was started in administrative divisions within the study area in April, 1998, to identify further EFE cases. We did a case-control study of households to investigate the risk from various environmental and health factors. Blood and urine samples were collected if possible and urine dicarboxylic acid concentrations measured by gas chromatography.

FINDINGS

29 cases of EFE were identified from January to May, 1998. Estimated age-specific attack rates (2-6 years) ranged from 31 to 847 per 100,000 population (p<0.001). The most common symptoms were hypotonia, vomiting, convulsions, and coma. All children died in 2-48 h. The only factor associated with EFE was the presence of ackee trees (Blighia sapida) within 100 m of households (odds ratio 5.1 [95% CI 1.8-14.7] p=0.001). Poisoning with unripe ackee fruits was suggested by urine concentrations of dicarboxylic acids four to 200 times higher in cases (n=2) than in controls (n=3).

CONCLUSION

Consumption of unripe ackee fruit probably caused this epidemic and may lead to a substantial number of unexplained deaths in preschool children in west Africa every year. Educational campaigns have the potential to prevent these deaths.

[Assessing severe maternal anemia and its consequences: the value of a simple examination of the coloration of palpebral conjunctiva]

The aims of this study were: (1) to investigate the relationship between pre-delivery hemoglobin (Hb) concentration and the outcome of the pregnancy for the mother and child and (2) to assess the extent to which the pallor of the conjunctiva indicates severe anemia in pregnancy (Hb < 7 g/dl). We carried out a prospective study in 1995, in the maternity department of the National Sourô Sanou Hospital (Bobo-Dioulasso, Burkina Faso). Women arriving to give birth at the maternity unit gave verbal consent and underwent a physical examination including the assessment of conjunctiva coloration. Finger-prick blood samples were taken from all the women selected and Hb was determined with a portable hemoglobin meter (HemoCue AB, Sweden). For each woman, information about age, obstetric history, the condition of mother and child at admission and delivery and any post-delivery complications in the first 48 hours was collected before discharge from the maternity unit, 3 to 5 days after the delivery. Women with multiple pregnancies were excluded from the study and 247 women were included overall. Endometriosis was observed in only three cases. Three women died, two due to septic shock. The third woman died from hypovolemic shock. The Hb concentrations of these women were 8 g/dl, 10.2 g/dl and 2.6 g/dl respectively. The mean Hb concentration for our population was 10.1 g/dl (SD = 2.08), with 165 women (67%) having less than 11 g Hb/dl. Forty-one women (17%) had less than 9 g Hb/dl and 16 (6%) had less than 7 g Hb/dl. Severe maternal anemia and pallor of the conjunctiva were significantly associated with pre-term delivery and perinatal death, but not with low birth weight. The sensitivity of the pallor of the conjunctiva for detection of severe maternal anemia was 87%, and its specificity was 88%. We found no evidence that maternal Hb levels of 9 to 10.9 g/dl were associated with a high risk of poor pregnancy outcome for either the mother or the child, although women with such levels of Hb are classed as anemic by the World Health Organization criteria. These results show that poor pregnancy outcome is associated with severe maternal anemia. Examination of the coloration of the conjunctiva is a suitable and affordable screening method for the detection of severe anemia. Mothers with severe anemia present with signs and symptoms of anemia and could therefore be given iron treatment to improve their health. This demonstrates the importance of nutritional intervention during pregnancy.

Measuring hygiene practices: a comparison of questionnaires with direct observations in rural Zaïre

To date questionnaire surveys have been the most commonly used instruments to measure hygiene behaviours related to water and sanitation. More recently, a number of studies have used structured observations to study practices related to diarrhoea. During a trial of a hygiene education intervention to reduce diarrhoea among young children in Bandundu, Zaire, both instruments were used to measure the disposal of child faeces and various hand-washing practices. Three hundred families were observed and follow-up interviews performed with 274 (91%) mothers. At the individual level, agreement between observed and reported behaviour was little better than might be expected by chance. There was evidence of over-reporting of hand-washing before food preparation (44% vs 33%; P = 0.03), hand-washing before eating (76% vs 60%; P < 0.001) and disposal of the child's faeces in a latrine (75% vs 40%; P < 0.001). On the other hand, hand-washing before feeding the child was reported less often than it was observed (7% vs 64%; P < 0.001). Our data are consistent with the hypothesis that, in general, mothers over-report 'desirable' behaviours. At the same time, our data indicate that open questions may lead to under-reporting of certain behaviours. The repeatability of observations at both the individual and population levels remains to be established.

Transmissions to mice indicate that 'new variant' CJD is caused by the BSE agent

There are many strains of the agents that cause transmissible spongiform encephalopathies (TSEs) or 'prion' diseases. These strains are distinguishable by their disease characteristics in experimentally infected animals, in particular the incubation periods and neuropathology they produce in panels of inbred mouse strains. We have shown that the strain of agent from cattle affected by bovine spongiform encephalopathy (BSE) produces a characteristic pattern of disease in mice that is retained after experimental passage through a variety of intermediate species. This BSE 'signature' has also been identified in transmissions to mice of TSEs of domestic cats and two exotic species of ruminant, providing the first direct evidence for the accidental spread of a TSE between species. Twenty cases of a clinically and pathologically atypical form of Creutzfeldt-Jakob disease (CJD), referred to as 'new variant' CJD (vCJD), have been recognized in unusually young people in the United Kingdom, and a further case has been reported in France. This has raised serious concerns that BSE may have spread to humans, putatively by dietary exposure. Here we report the interim results of transmissions of sporadic CJD and vCJD to mice. Our data provide strong evidence that the same agent strain is involved in both BSE and vCJD.

A community-based programme to provide prompt and adequate treatment of presumptive malaria in children

A community-based programme to ensure prompt and adequate treatment of presumptive episodes of clinical malaria in children has been established in a rural province of Burkina Faso. The implementation strategy was based on training a core group of mothers in every village and supplying community health workers with essential antimalarial drugs specially packed in age-specific bags containing a full course of treatment. Drugs were sold under a cost-recovery scheme. The programme was run in 1994 by the national malaria control centre (CNLP), and in 1995 it was developed to the provincial health team (PHT). Knowledge and awareness of malaria increased with the intervention. Drug consumption by age group was compatible with the distribution of disease, and no major problem of misuse emerged. The actual implementation costs of the intervention were US$ 0.06 per child living in the province. An evaluation of the impact of the intervention on the severity of malaria, using routine data from the health information system and taking as an indicator the proportion of malaria cases which were recorded as severe in health centres, was performed. In 1994, when the intervention was implemented on a provincial scale by CNLP, this proportion was lower than the average of the 4 preceding years (3.7% vs. 4.9%). In 1995, when the programme was implemented by the PHT, the proportion of severe cases was lower in health centres achieving a programme coverage of > or = 50% in their catchment area compared with the others (4.2% vs. 6.1%). Our experience shows that a low-cost, community-based intervention aimed at providing children with prompt and adequate treatment of presumptive episodes of clinical malaria is feasible, and suggests that it may lead to a reduction in the morbidity from severe malaria.

Dirt and diarrhoea: formative research in hygiene promotion programmes

Investment in the promotion of better hygiene for the prevention of diarrhoeal diseases and as a component of water and sanitation programmes is increasing. Before designing programmes capable of sustainably modifying hygiene behaviour in large populations, valid answers to a number of basic questions concerning the site and the intended beneficiaries have to be obtained. Such questions include 'what practices favour the transmission of enteric pathogens?', 'what advantages will be perceived by those who adopt safe practices?' and 'what channels of communication are currently employed by the target population?' A study of hygiene and diarrhoea in Bobo-Dioulasso, Burkina Faso, used a mixture of methods to address such questions. This paper draws on that experience to propose a plan of preliminary research using a variety of techniques which could be implemented over a period of a few months by planners of hygiene promotion programmes. The techniques discussed include structured observation, focus group discussions and behavioural trials. Modest investment in such systematic formative research with clear and limited goals is likely to be repaid many times over in the increased effectiveness of hygiene promotion programmes.

CD4+ T-lymphocyte counts in HIV infection: are European standards applicable to African patients?

CD4+ lymphocyte count (CD4+ LC) is a widely used marker of Human Immunodeficiency Virus (HIV) immune impairment. Physiological lymphocytosis is frequently encountered in Africans. Therefore, we tried to determine if given CD4+ LC levels are of similar significance in European versus African HIV-infected individuals. Lymphocyte phenotyping of 750 HIV-infected adults was retrospectively analyzed. Three hundred and seventy patients were consecutively selected in Paris, France; 185 in Abidjan, Côte d'Ivoire; and 195 in Bobo-Dioulasso, Burkina Faso. In the three settings, lymphocyte phenotyping was performed by flow cytometry using similar protocols. Data from Abidjan and Bobo-Dioulasso were combined on the basis of geographic proximity and contrasted with those from Paris. Geometric mean levels of Total Lymphocyte Count (TLC), CD4+ LC, CD8+ lymphocyte count (CD8+ LC), and CD4:CD8 ratio, adjusted for percentage of CD4+ T-cells (%CD4+), were compared between Africans and Europeans. For a given %CD4+, TLC and CD4+ LC but not CD8+ LC tended to be about one third higher in West African than in French adults (p < 0.0001). Approximate equivalencies of absolute CD4+ counts in French and West African HIV-infected adults suggest that where thresholds of 200 and 500 CD4+ cells/microliter are applied in Europe, it might be appropriate to apply a threshold of approximately 250 and 700 CD4+ cells/microliter in West Africa, respectively. Establishing indicators of progression of HIV infection with locally appropriate thresholds may represent important steps toward improvement of HIV disease management in Africa.

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.

Reactivity and repeatability of hygiene behaviour: structured observations from Burkina Faso

If interventions promoting improved hygiene behaviour to prevent childhood diarrhoea are to be implemented and evaluated, valid methods for measuring this behaviour will be required. This paper presents findings from a study to investigate the use of structured observations to measure hygiene behaviour in Burkina Faso. Two hundred mothers with young children (2-36 months) were observed on several occasions, with particular attention focused on events/behaviour surrounding defaecation. Child defaecation occurred most often in a potty (67% of occasions). Stools were most often disposed of into a latrine (79%). Following defaecation the child's bottom was usually rinsed using water alone with a bare hand (76%). Subsequent hand washing by the mother/caretaker was much rarer (29%). None of these behaviours appeared "reactive" to the presence of the observer. Less common behaviors showed some evidence of reactivity. The frequency of child defaecation in the yard increased over the course of three observations (5% to 16%; P = 0.01) and the proportion of occasions on which the child was observed to be cleaned after defaecation declined (95% to 85%; P = 0.01). Mothers usually took with them to the latrine a water recipient (91%). Hand washing after leaving the latrine was observed on 30% of occasions. This proportion declined from 36% to 22% over three observations (P = 0.05). Defaecation by older siblings (aged 3-5 years) was usually into a potty (48%) or directly in a latrine (30%). There was no evidence that this behaviour was reactive. The repeatability of behaviours at the individual level was generally low. The site of index child defaecation (kappa = 0.27), how the child's bottom was cleaned (kappa = -0.01) and whether the caretaker washed her hands afterwards (kappa = 0.26) all showed low repeatability. The method of stool disposal was more repeatable (kappa = 0.73). Hand washing by mothers after using the latrine showed moderate repeatability (kappa = 0.40). Older sibling's defaecation behavior had excellent repeatability (kappa = 0.90). Our findings suggest that, in studies which aim to measure behaviour at the population level, structured observations may provide a useful tool. Studies which investigate links between hygiene behaviour and diarrhoea incidence at the individual level will require repeated observations of mothers and children since measuring behaviour during a single observation will lead to misclassification of exposure status, resulting in bias which could mask any underlying association. This is likely to be very costly.

Anaemia among women of reproductive age in Burkina Faso

The control of anaemia among women of reproductive age (15-49 years) is one of the priorities of the Safe Motherhood initiative. This article presents the results of a study that was carried out to provide some of the information needed for an effective and sustainable programme to control anaemia in women of this age group in Burkina Faso.

Potties, pits and pipes: explaining hygiene behaviour in Burkina Faso

Stool disposal practices have been shown to be associated with childhood diarrhoea. However, efforts to promote improved hygiene behaviour are hampered by a lack of understanding of what determines those behaviours. Data from 2793 household interviews with mothers of children from the town of Bobo-Dioulasso in Burkina Faso were analyzed to examine what differentiated mothers who reported using safer stool disposal practices from those who did not. Three 'outcomes' were considered: where the child was reported to defaecate; where the mother reported disposing of the child stools; and whether excreta were observed in the compound. Regression models were developed to identify those factors with the strongest independent associations with the outcomes. There was a consistent association between the source of water and the outcomes. Mothers with access to a tap in the yard reported using safe hygiene practices three times more often than mothers using wells outside the compound and twice as often as mothers who used public standpipes or wells within the yard. The source of water showed a similar pattern of association with observations of faecal matter in the environment. Improved sources of water may contribute to safer stool hygiene by reducing the time spent on water collection or by encouraging mothers to conform to higher standards of hygiene. Other factors which played a role in predicting the hygiene behaviour of mothers were the husbands' occupation, the number of health education sessions that she had attended, her zone of residence and family ownership of certain valuable objects. These factors are likely to be related and to be, to some extent, proxies for the real determinants of her behaviour. A model of the cultural, psycho-social and infrastructural proximate determinants of hygiene behaviour is proposed. Data from focus group discussions suggested that the main purpose of hygienic behaviour is to conform to existing norms of social etiquette. Trials of interventions based on changing such norms are needed to test whether this is an effective means of promoting of safer hygiene practices.

Ivermectin and onchocercal optic neuritis: short-term effects

In 1982 the macrocyclic lactone, ivermectin, was first tested in human patients with onchocerciasis. It has since undergone phase I to IV trials and is now being widely distributed in onchocercal areas. The previous microfilaricide, diethylcarbamazine citrate (DEC), is known to precipitate or exacerbate active optic neuritis in some onchocercal patients, as part of a wider inflammatory response (the Mazzotti reaction). Ivermectin may also cause a mild reaction, especially in people with high microfilarial loads. Few data are available concerning the effect of ivermectin on active optic neuritis. A large, randomised, double-masked, phase IV trial is reported. Individuals were screened for evidence of optic nerve disease (OND), and those identified as possible cases of OND underwent detailed ophthalmic examination, including fluorescein angiography, before being dosed with ivermectin or placebo. A total of 6831 persons were screened of whom 856 (13%) underwent angiography prior to dosing. At 7-14 days after dosing an attempt was made to re-examine 50% of adults over the age of 20 years, including all those with OND. Six hundred and eighty-eight repeat or new angiograms were performed. During this period, 5 new cases of active optic neuritis and one case of exacerbation of existing optic neuritis were identified. Five of these individuals had received placebo and one ivermectin. Two individuals with optic neuritis before dosing had improved after 7-14 days. One had received placebo, the other ivermectin. Ivermectin does not appear to precipitate or exacerbate optic neuritis at a period of 7-14 days.

Child defecation behaviour, stool disposal practices, and childhood diarrhoea in Burkina Faso: results from a case-control study

OBJECTIVE

To investigate the association between where young children defecate, where stools are disposed of, and the presence of human stools on the ground in the compound and the rate of hospital admission with diarrhoea.

DESIGN

This was a case-control study with two control groups.

SETTING

The study took place in Bobo-Dioulasso, the second city of Burkina Faso in West Africa.

PARTICIPANTS

Three groups of children aged 36 months and under, and living in Bobo-Dioulasso were studied. Cases were 757 children admitted to hospital with symptoms of diarrhoea or dysentery. The first control group comprised 757 neighbourhood control children approximately matched on age and date of recruitment, and the second, 631 children admitted to the same hospital without symptoms of diarrhoea or dysentery.

MAIN RESULTS

There was no evidence of any association between where the child was reported to defecate and hospital admission with diarrhoea or dysentery (odds ratio = 1.10; 95% confidence interval (CI) 0.78, 1.57, cases v neighbourhood controls; odds ratio = 0.84; 95% CI 0.60, 1.18, cases v hospital controls). There was evidence of an association between where the mother reported disposing of the child's stools and hospital admission with diarrhoea or dysentery (odds ratio = 1.50; 95% CI 1.09, 2.06, cases v neighbourhood controls; odds ratio = 1.31; 95% CI 0.96, 1.79, cases v hospital controls). Human stools were more frequently observed in the yards of cases than controls (odds ratio = 1.38; 95% CI 0.98, 1.95, cases compared with neighbourhood controls; odds ratio = 1.33; 95% CI 0.96, 1.84, cases compared with hospital controls).

CONCLUSIONS

The findings suggest that it is not where the child defecates that matters but how the mother then deals with the child's stools.

[Acute respiratory infections in pediatric hospital at Bobo-Dioulasso (Burkina Faso)]

BACKGROUND

Acute lower respiratory tract infections are the primary cause of morbidity in developing countries.

POPULATION AND METHODS

Six hundred and sixty seven children (379 boys, 288 girls, aged 0-30 months) admitted for lower respiratory tract infections from January 1990 to March 1991 were included in the study. Immediate medical history was collected from the mother. The weight, height, temperature and clinical manifestations, plus the results of chest X-rays, parasitologic and bacteriological examination of stools, and blood smear for malaria were recorded for each patient. Sero-immunologic study for HIV infection of 473 of the patients aged 12-36 months and their mothers also took part in a sero-immunological study for HIV infection.

RESULTS

Lower respiratory tract infections were the second major cause of admission (16.8%) after malaria (28.7%). Infections peaked between 6 and 11 months of age (29.5%). The main diseases were pneumonia and bronchial pneumonia (54%) followed by bronchiolitis (21.7%). Almost half the patients were admitted during the hot, dry season. Two hundred and eighty seven patients (43.4%) were referred only after they had been suffering from the disease for 3 to 9 days, partly explaining the high level of mortality. One hundred and twenty one patients (20.9%) died; the main cause of death was staphylococcal pneumonia (57.9%), followed by pneumonia and bronchial pneumonia (29.3%). Some criteria for severity could be identified, based on pulmonary signs and symptoms and associated manifestations (dehydration, malnutrition, convulsions, anemia). Twenty two patients were positive for HIV-1 infection.

CONCLUSIONS

This study confirms that acute lower respiratory tract infections remain a public health problem. Early diagnosis and treatment are necessary to reduce mortality.

Distribution and aetiology of blindness and visual impairment in mesoendemic onchocercal communities, Kaduna State, Nigeria. Kaduna Collaboration for Research on Onchocerciasis

During a field trial of ivermectin in Kaduna State, 6831 people age 5 years and above, living in 34 mesoendemic onchocercal communities in Kaduna State, northern Nigeria, were examined for ocular disease. Visual function assessments included tests of visual acuity and visual fields. A total of 185 individuals (2.7%) were bilaterally blind by acuity criteria with a further 28 blind by field constriction. The overall prevalence of blindness was 3.1%. A further 118 individuals were visually impaired by WHO criteria. Examination for the cause of blindness revealed that 43% of eyes in bilaterally blind patients were blind due to onchocerciasis. A further 11% were blind from optic atrophy much of which was probably onchocercal in origin. Glaucoma was the next most common cause of blindness in the bilaterally blind (11%). Only 6% of eyes were blind from cataract as the primary cause. In the visually impaired population cataract was the most common primary cause of impaired/blind eyes (31%), followed by onchocerciasis (19%) [corrected].

A clinical classification and grading system of the cutaneous changes in onchocerciasis

Although onchocerciasis is one of the most important diseases of the skin and eye in the tropical world, to date there has been no formal consensus regarding the description and terminology of skin lesions. Furthermore, the contribution of cutaneous pathology to the morbidity and socio-economic effects of the disease has been largely neglected. We present a clinical classification and grading system for recording the cutaneous changes of onchocerciasis, and propose that this system be used as a standard method of description to convey clinical information between workers in all endemic areas to assist local and comparative research.