Rotavirus and other Diarrheal Disease in a Birth Cohort from Southern Indian Community.

Objective: To describe the incidence, severity and etiology of diarrheal disease in infants and young children residing in an urban slum community in Southern India. Setting: Three contiguous urban slums in Vellore, Tamil Nadu. Participants: 452 children participating in a birth cohort study on diarrheal disease; 373 completed three years of follow-up. Outcome measures: Diarrheal incidence (obtained by twice-weekly home visits) and severity (assessed by the Vesikari scoring system), and etiological agents associated with diarrhea (through examination of stool specimens by bacteriologic culture, rotavirus enzyme immunoassay, PCR for norovirus and microscopy for parasites). Results: A total of 1856 diarrheal episodes were reported in 373 children. The overall incidence rate of diarrhea was 1.66 episodes per child year for three years, with 2.76 episodes per child year in infancy. The incidence peaked during the months of July and August. Severe diarrhea formed 8% of the total episodes. Rotavirus was the most common pathogen detected, being identified in 18% of episodes. Good hygiene status resulted in 33% protection against moderate-to-severe diarrhea. Conclusions: This study highlights the burden of diarrheal disease and the important etiological agents of childhood diarrhea in Southern India. Promotion of hygienic behavior through health education may help reduce diarrheal incidence in this and similar communities.

Maternal periodontal disease as a significant risk factor for low birth weight in pregnant women attending a secondary care hospital in South India: A Case-control study.

Context: Periodontal disease (PD) is a common infection in the community; however, its relationship with low birth weight (LBW) has not been well‑established. Aims: The aim was to determine the association between maternal PD and LBW. Settings and Design: A case–control (1:1) study. Materials and Methods: The study population comprised of women who delivered at the hospital during the study period (September 2011 to February 2012).Women between 18 and 35 years of age, who delivered singleton, live infants during study period with at least 18 teeth were enrolled. Those with pregnancy induced hypertension, gestational diabetes, blood‑borne viral infections, periodontal treatment within the past 6 months and valvular heart disease were excluded. Control population was parity matched to the cases. Statistical Analysis Used: Chi‑square test, t‑test and univariant and multivariant logistic regression were used to analyze various study findings, and level of significance was set at 5% (P < 0.05). Results: PD was independently associated with LBW (odds ratio: 4.94, 95% confidence interval: 1.03–23.65, P=0.045). Additionally, conventional risk factors such as maternal height (P=0.029), secondary schooling (<8 years of schooling) (P = 0.001), socio‑economic status (P = 0.046), type of family (joint) (P = 0.008), number of ante‑natal visits (P = 0.028) and gestational age at birth (<37 weeks) (P = 0.045) showed significant association with LBW. Conclusions: There seems to be an association between PD and LBW independent of conventional risk factors. Women who had PD were 5 times more likely to deliver LBW infants.

Risk factors for acquiring Strongyloides stercoralis infection among patients attending a tertiary hospital in south India.

Purpose: Strongyloides stercoralis causes persistent and fatal disseminated infections in immunocompromised hosts. In this study, we aimed to determine the risk factors for acquiring strongyloidiasis and the associated morbidity in south India. Materials and Methods: The study was carried out in two parts. This included a 6-month chart review of cases with strongyloidiasis and randomly selected controls conducted to determine the association with immunocompromised states. Secondly, a cross-sectional study was conducted to investigate hyperinfection in human immunodeficiency virus (HIV)-infected adults where the stool and sputum samples were examined by microscopy for Strongyloides larvae. Results: In the chart review, 118 cases were compared with 240 controls. A higher proportion of patients on corticosteroids [8 (53.3%)] and with HIV infection [3 (60%)] had the risk of acquiring strongyloidiasis than not, although the difference was not statistically significant in this population. In the cross-sectional study, 14/239 HIV-positive individuals had Strongyloides larvae in the stool samples but none had Strongyloides detectable in their sputum samples. The CD4 cell counts were significantly lower in cases with Strongyloides compared with HIV-infected individuals with no parasites in their stool samples (P < 0.001). Conclusions: In this setting, strongyloidiasis was seen more often in patients on corticosteroid therapy and with HIV infection. In HIV, an association with lower CD4 counts indicates the need for inclusion of Strongyloides as an opportunistic parasite. Gram negative sepsis was an important complication of strongyloidiasis hyperinfection in both HIV and steroid therapy. Further prospective studies on the risk of developing complicated Strongyloides infection are required.

Knowledge of epidemiology and statistics for an ophthalmic practitioner.

Ophthalmologists are frequently confronted with treatment options that claim to be better than those currently in use. Statistically significant P values are invariably provided by way of proof. For many ophthalmologists a simple look at this revered P value is enough evidence that a statistically significant result has indeed been obtained. Unfortunately, traditional interpretation of a study based on the P value at an arbitrary cut-off (P<0.05 or any other value) limits the ability to fully appreciate clinical implications. In this article the authors introduce the reader to and illustrate the use of "confidence intervals" as opposed to P values in examining the applicability of study results. Further, what is statistically significant may not necessarily be clinically significant; perhaps not enough for the practitioner to change from the currently preferred method of treatment. To resolve this, the authors have also used common ophthalmic examples to introduce the "number needed to treat", as a simple clinical approach for the practising ophthalmologist wishing to assess the clinical significance of treatment options.

Antibody response to a single tetanus toxoid booster in young women in rural south India.

BACKGROUND: Tetanus toxoid immunization is an integral part of the maternal and child health programme in developing countries. It is likely that many women may have had childhood immunization and so already have antitetanus antibodies at the time of their first antenatal visit. A single dose of tetanus toxoid injection can boost the levels of antitetanus antibodies in these women. This study was undertaken to assess the previous immunization status by verbal history and assess the effect of a single tetanus toxoid injection in young women. METHODS: Ninety-nine unmarried women between 18 and 22 years of age were enrolled for the study. The history of childhood immunization was obtained from their mothers. Blood samples were collected to measure IgG antibody levels to tetanus using ELISA. Antibody levels were also measured on day 14 after a dose of tetanus toxoid injection. RESULTS: Of the 99 women studied, 81 had a history of childhood immunization while 18 did not. Overall, 92% of the women had protective levels of antibodies at the time of first testing and 99% of the women were protected with a single dose of tetanus toxoid. CONCLUSION: In areas with good maternal and child health services, a single booster dose of tetanus toxoid can be considered adequate for primigravidae with a history of childhood immunization.

Comparison of optical and ultrasound pachometry.

PURPOSE: (1) To determine the agreement between optical and ultrasound pachometry for central corneal thickness measurements used to "correct" applanation intraocular pressure (IOP) readings. (2) To determine the inter- and intra-observer variability of optical and ultrasound pachometry. METHOD: Central corneal thickness (CCT) was measured in a masked manner using optical and ultrasound pachometry in 50 normal eyes. To assess intra- and inter-observer variability, multiple masked measurements were obtained in 51 eyes (optical pachometry) and 34 eyes (ultrasound pachometry). Agreement was determined by a published technique that uses the mean of the differences, standard error (SE) and standard deviation (SD). RESULTS: The mean difference in CCT between optical and ultrasound pachometry was 0.001 mm (SD 0.031 mm; SE 0.00439 mm). The mean inter-observer difference for the optical pachometer was 0.019 mm (SD 0.049 mm; SE 0.0069); the mean intra-observer difference was 0.003 mm (SD 0.017; SE 0.0.0024). The mean inter-observer difference for ultrasound pachometry was 0.001 mm (SD 0.009; SE 0.0015) and the mean intra-observer difference was 0.002 mm (SD 0.011; SE 0.0019). CONCLUSIONS: Ultrasound pachometry is the more reliable method for the measurement of central corneal thickness used to correct applanation IOP values. Optical pachometry had good intra-observer variability. The range of error in IOP correction for corneal thickness (inter-observer) that can occur using the ultrasound pachometer is -1.2 mmHg to +1.4 mmHg as compared to -5.6 mmHg to +8.5 mmHg with the optical pachometer.

The role of central corneal thickness in the diagnosis of glaucoma.

PURPOSE: To determine the effect of central corneal thickness (CCT) on applanation tonometry and any resultant misclassification of normals as ocular hypertension. METHOD: The central corneal thickness was measured using the ultrasound pachometer in 50 normals, 25 glaucoma and 23 ocular hypertensive patients. The student's "t" test was used to determine any significant difference in CCT between the three groups. RESULTS: There was a statistically significant difference in the mean CCT of the ocular hypertensives (0.574 +/- 0.033 mm) as compared to the glaucomas (0.534 +/- 0.030 mm) and normals (0.537 +/- 0.034 mm). Applying the described correction factor for corneal thickness, 39% of eyes with ocular hypertension were found to have a corrected IOP of 21 mmHg or less. CONCLUSIONS: Increased corneal thickness in ocular hypertension may lead to an overestimation of IOP in 39% of cases. Measurement of central corneal thickness is advisable when the clinical findings do not correlate with the applanation IOP.

A high rate of caesarean sections in an affluent section of Chennai: is it cause for concern?

BACKGROUND: While rising Caesarean section rates have been the subject of much attention and debate worldwide, there is not much information available on this rate and its potential adverse impact in India. METHODS: Our survey was a standard Expanded Programme on Immunization 30-cluster design, carried out in an urban educated, middle/upper class population in Chennai. Mothers of 210 children aged 12-36 months were interviewed and data collected on immunization and breast-feeding practices. Since the mode of delivery was one of the questions, we could generate population-based data on the Caesarean section rate and its influence on breast-feeding. RESULTS: Of the 210 babies, 95 (45%, 95% confidence interval: 39.1-51.3) had been delivered by Caesarean section. Two hundred and six of 210 babies (98%) had been breast-fed at some time. However, babies born by Caesarean section tended to be started late on breast-feeds were given prelacteal feeds more often, and colostrum less often when compared to babies delivered vaginally (all statistically significant). CONCLUSIONS: Our study revealed a very high rate of Caesarean section in the selected metropolitan population. On purely scientific grounds, a rate of 40% to 50% is extremely difficult to justify. Though not conclusive, the data also suggest that Caesarean section may be adversely affecting some aspects of breast-feeding. There is a need for more data and audits on Caesarean section rates in India, and a wider debate on its potential adverse impact on the health of mothers and newborns.

An introduction to clinical decision analysis in ophthalmology.

Ophthalmologists are often confronted with difficult clinical management problems. In such cases, even published experience may be limited; consequently multiple, generally unproven management options are usually available. When placed in such situations, most of us decide on the most appropriate course of action based on intuition or (limited) previous experience. In this article, we use examples to introduce the concept of decision analysis, a method of generating objective decisions for complex clinical problems.

The incidence of cataract in India is an overestimate.

BACKGROUND: Data obtained from surveys using distant direct ophthalmoscopy (DDO) with an undilated pupil for the detection of cataracts suggest an annual incidence of 3.8 million cataracts and over 9 million cataract-blind people in India today. METHOD: We recalculated the projections after adjusting for the sensitivity and specificity of DDO. RESULTS: Our calculations suggest that the incidence of cataract may have been overestimated by approximately 60%; corroborative evidence is provided. CONCLUSIONS: The specificity and sensitivity of diagnostic tests used in surveys may distort the projected figures and have adverse implications for the planning of services.

Prevalence of primary glaucoma in an urban south Indian population.

Glaucoma is fast emerging as a major cause of blindness in India. In order to estimate the prevalence of primary open angle glaucoma (POAG) and primary angle closure glaucoma (PACG) in an urban South Indian population, we examined 972 individuals aged 30-60 years, chosen using a cluster sampling technique from 12 census blocks of Vellore town. They underwent a complete ocular examination, including applanation tonometry and gonioscopy, at the Medical College Hospital. Characteristic field defects on automated perimetry was a diagnostic requisite for POAG. Prevalence (95% CI) of POAG, PACG, and ocular hypertension were 4.1 (0.08-8.1), 43.2 (30.14-56.3), and 30.8 (19.8-41.9) per 1,000, respectively. All the PACG cases detected were of the chronic type. Hitherto unavailable community-based information on primary glaucoma in our study population indicates that PACG is about five times as common as POAG.

Incidence of disabilities among multi-bacillary cases after initiation of multidrug therapy and factors associated with the risk of developing disabilities.

Out of the 1724 new cases registered between 1985 to 1992, 1169 could be contacted. The overall incidence of disabilities was 6.8%. Age above 45 years, bacteriopositivity and thickening of three or more trunk nerves were associated with a higher risk of disabilities. Staff training, patient education and steroid availability in the field were the suggested methods of reducing the occurrence of disabilities in leprosy patients.

Evaluation of the role of syringing prior to cataract surgery.

Patients for cataract surgery in India routinely undergo preoperative syringing to rule out chronic dacryocystitis. We determined the sensitivity and specificity of the clinical test of regurgitation on pressure over the lacrimal sac (ROPLAS) as a screening test for chronic dacryocystitis and compared it to syringing. 621 consecutive outpatients who needed syringing for various reasons (including 318 who had routine syringing prior to cataract surgery) were examined in a masked manner for regurgitation on pressure over the lacrimal sac. They then underwent syringing by a trained (masked) observer. The sensitivity and specificity of ROPLAS were 93.2% and 99.3%, respectively. Using a 6.6% prevalence of chronic dacryocystitis (the prevalence in our cataract population), the negative predictive value of the test was 99.5%. In the presence of regurgitation of pressure over the sac, the high specificity of ROPLAS confirms chronic dacryocystitis. In view of the opportunity costs, when ROPLAS is negative, preoperative syringing in cataract is perhaps unnecessary, unless the findings are equivocal or the index of suspicion for chronic dacryocystitis is very high.

An epidemic of diarrhoea in south India caused by enteroaggregative Escherichia coli.

A diarrhoeal epidemic in a village close to Vellore was investigated in January 1996. Faecal samples were obtained from 20 subjects with diarrhoea and from 11 individuals without diarrhoea (controls) and were examined for bacterial, viral and parasitic enteropathogens. Water samples from all sources in the village were analysed. The epidemic affected all age groups (overall attack rate 15%). The mean duration of diarrhoea was 11 days. Individuals who consumed water exclusively from a borewell had a lower relative risk (RR) of disease (0.14, 95% Cl 0.02-1.01) compared to users of two open wells (RR 6.93, Cl 0.99-48.66 and RR 7.81, Cl 1.02-59.79, respectively). No conventional bacterial enteropathogens were isolated from the stool samples. Enteroaggregative Escherichia coli (EAggEC) were identified in the stool of 11 of 20 subjects with diarrhoea, and in 1 of 11 control samples (P = 0.02). All the EAggEC isolates from the patients had identical antibiotic sensitivity patterns and produced a toxin in Ussing chamber studies. Serotyping indicated that all the EAggEC from individuals with diarrhoea belonged to one or other of two serotypes. All water samples had high coliform counts and E. coli were cultured from the two open wells but not from the borewell. The evidence suggests that EAggEC was responsible for this outbreak of diarrhoea. EAggEC should be considered as a possible pathogen in unexplained diarrhoeal outbreaks in developing countries.

Confidence with confidence intervals.

When considering the results of a study that reports one treatment to be better than another, what the practicing ophthalmologist really wants to know is the magnitude of the difference between treatment groups. If this difference is large enough, we may wish to offer the new treatment to our own patients. Even in well executed studies, differences between the groups (the sample) may be due to chance alone. The "p" value is the probability that the difference observed between the groups could have occurred purely due to chance. For many ophthalmologists assessing this difference means a simple look this "p" value to convince ourselves that a statistically significant result has indeed been obtained. Unfortunately traditional interpretation of a study based on the "p" value at an arbitrary cut-off (of 0.05 or any other value) limits our ability to fully appreciate the clinical implications of the results. In this article we use simple examples to illustrate the use of "confidence intervals" in examining precision and the applicability of study results (means, proportions and their comparisons). An attempt is made to demonstrate that the use of "confidence intervals" enables more complete evaluation of study results than with the "p" value.

VISTECH contrast sensitivity testing in primary open angle glaucoma.

Contrast sensitivity has been recommended as a screening and diagnostic test in primary open angle glaucoma (POAG). We tested contrast sensitivity (CS) using Vistech charts in 184 eyes of 95 patients. Three groups were examined--established primary open angle glaucoma, glaucoma suspects and age matched controls. The distribution of contrast sensitivities amongst the three groups were similar. The median contrast sensitivity of glaucoma suspects and controls were well within normal limits while that of the POAG group fell along the lower limit of normal. In all three groups the younger subjects scored better than the older, indicating a depression of contrast sensitivity with increasing age. Even if depression of any one spatial frequency was considered abnormal, the test yielded a sensitivity of 55.4% and specificity of 69.5%. Similarly contrast sensitivity testing was found to be of little use in detecting field defects a maximum sensitivity of 47.3% and specificity of 73.3%. Vistech contrast sensitivity testing is not a useful test in POAG screening or diagnosis.