High-resolution melt curve analysis: An approach for variant detection in the TPO gene of congenital hypothyroid patients in Bangladesh

TPO (Thyroid Peroxidase) is known to be one of the major genes involved in congenital hypothyroid patients with thyroid dyshormonogenesis. The present study aims to validate high-resolution melting (HRM) curve analysis as a substitute method for Sanger sequencing, focusing on the frequently observed non-synonymous mutations c.1117G>T, c.1193G>C, and c.2173A>C in the TPO gene in patients from Bangladesh. We enrolled 36 confirmed cases of congenital hypothyroid patients with dyshormonogenesis to establish the HRM method. Blood specimens were collected, and DNA was extracted followed by PCR and Sanger sequencing. Among the 36 specimens, 20 were pre-sequenced, and variants were characterized through Sanger sequencing. Following pre-sequencing, the 20 pre-sequenced specimens underwent real-time PCR-HRM curve analysis to determine the proper HRM condition for separating the three variations from the wild-type state into heterozygous and homozygous states. Furthermore, 16 unknown specimens were subjected to HRM analysis to validate the method. This method demonstrated a sensitivity and specificity of 100 percent in accurately discerning wild-type alleles from both homozygous and heterozygous states of c.1117G>T (23/36; 63.8%), c.1193G>C (30/36; 83.3%), and c.2173A>C (23/36; 63.8%) variants frequently encountered among 36 Bangladeshi patients. The HRM data was found to be similar to the sequencing result, thus confirming the validity of the HRM approach for TPO gene variant detection. In conclusion, HRM-based molecular technique targeting variants c.1117G>T, c.1193G>C, and c.2173A>C could be used as a high throughput, rapid, reliable, and cost-effective screening approach for the detection of all common mutations in TPO gene in Bangladeshi patients with dyshormonogenesis.

Sex-Specific Total Testosterone and Dehydroepiandrosterone Sulfate Status in Noncritically Ill Hospitalized Patients with Coronavirus Disease 2019: A Cross-Sectional Study

BACKGROUND

In individuals with coronavirus disease 2019 (COVID-19), male subjects have consistently been linked to poor severity and prognosis. Data on sex hormones in non-critical COVID-19-infected patients are scarce. The aim of this study was to assess the status of total testosterone (TT) and dehydroepiandrosterone sulfate (DHEAS) among noncritical patients with COVID-19 according to sex and their associations with clinical and biochemical features.

MATERIALS AND METHODS

This cross-sectional observational study was done in the COVID-19 unit of a University hospital during the period of September 2021 to February 2022 among 91 adults (18-65 years) with reverse transcriptase- polymerase chain reaction confirmed noncritical COVID-19 patients. Blood was drawn by venipuncture before receiving steroids between 07:00 to 09:00 a.m. in a fasting state to measure serum TT and DHEAS by chemiluminescent microparticle immunoassay. Diagnosis and classification of COVID-19 were done according to World Health Organization's interim guidance. Age- and sex-specific laboratory reference values were used to classify the TT and DHEAS status of the patients.

RESULTS

Only three males (8.1%) had low TT and the rest had normal TT. On the other hand, 15 (27.8%) of the females had high TT with normal levels in the rest. Similarly, 11 (29.7%) males had low DHEAS. Females had low, normal, and high DHEAS in four (7.4%), 48 (88.9%), and two (3.7%) cases respectively. Males with moderate severity of COVID-19 had significantly lower DHEAS (post hoc P=0.038) than the mild group. Both TT (P=0.008) and DHEAS (P=0.023) significantly correlated with neutrophils/lymphocytes ratio and only DHEAS with platelets/lymphocytes ratio (P=0.044) in males. In females, TT significantly correlated with serum sodium (P=0.034).

CONCLUSION

In noncritical COVID-19 patients, substantial gender variations in TT and DHEAS were detected and correlated with severity markers in males.

Ovarian volume is more closely related to the different manifestations of polycystic ovary syndrome than follicle number per ovary

OBJECTIVE

Polycystic ovary (PCO), a diagnostic component of polycystic ovary syndrome (PCOS), requires either an ovarian volume (OV) criterion or a follicle number per ovary (FNPO) criterion. This study investigated the association of OV and FNPO criteria with various manifestations of PCOS.

METHODS

This cross-sectional study was conducted at a university hospital among 100 patients newly diagnosed with PCOS (according to the revised Rotterdam criteria). Fasting blood samples were collected to measure glucose, total testosterone (TT), luteinizing hormone (LH), follicle-stimulating hormone (FSH), lipid, insulin, and hemoglobin A1c levels. An oral glucose tolerance test was performed. Transabdominal or transvaginal ultrasound of the ovaries was done, depending on patients' marital status. All investigations were conducted in the follicular phase of the menstrual cycle. OV >10 mL and/or FNPO ≥12 indicated PCO. A homeostasis model assessment of insulin resistance (IR) value ≥2.6 indicated IR, and metabolic syndrome (MS) was defined according to the international harmonization criteria.

RESULTS

Seventy-six participants fulfilled the OV criterion, 70 fulfilled the FNPO criterion, and 89 overall had PCO. Both maximum OV and mean OV had a significant correlation with TT levels (r=0.239, p=0.017 and r=0.280, p=0.005, respectively) and the LH/FSH ratio (r=0.212, p=0.034 and r=0.200, p=0.047, respectively). Mean OV also had a significant correlation with fasting insulin levels (r=0.210, p=0.036). Multivariate binary logistic regression analysis showed that IR (odds ratio [OR], 9.429; 95% confidence interval [CI], 1.701 to 52.271; p=0.010) and MS (OR, 7.952; 95% CI, 1.821 to 34.731; p=0.006) had significant predictive associations with OV alone, even after adjustment for age and body mass index.

CONCLUSION

OV may be more closely related to the androgenic and metabolic characteristics of PCOS than FNPO.

Hypothalamic-Pituitary-Adrenal Axis Activity in SARS-CoV-2 Infected Noncritically Ill Hospitalized Patients

Objectives

This study determined the baseline hypothalamic-pituitary-adrenal axis hormonal levels and their associated factors in noncritically ill hospitalized patients with coronavirus disease 2019 (COVID-19).

Methodology

This cross-sectional study was carried out in 91 noncritical RT-PCR-confirmed COVID-19 patients (aged 18 to 65 years) recruited consecutively from the COVID unit of two tertiary care hospitals over a period of six months. After the screening, relevant history and physical examinations were done, and blood was drawn between 07:00 am to 09:00 am in a fasting state to measure serum cortisol and plasma adrenocorticotropic hormone (ACTH) by chemiluminescent microparticle immunoassay.

Results

Of 91 patients, 54, 26, and 11 had mild, moderate, and severe COVID-19, respectively. Median values of serum cortisol (p = 0.057) and plasma ACTH (p = 0.910) were statistically similar among the severity groups. Considering a cortisol cut-off of 276 nmol/L (<10 μg/dL), the highest percent of adrenal insufficiency was present in severe (27.3%), followed by mild (25.9%) and least in the moderate (3.8%) COVID-19 cases. Using the cortisol/ACTH ratio >15, only 6.6% had enough reserve.

Conclusions

The adrenocortical response was compromised in a significant percentage of noncritically ill hospitalized patients with COVID-19, with the highest percentage of adrenal insufficiency present in severely infected cases. The HPA axis parameters of serum cortisol, plasma ACTH and cortisol/ACTH were similar across the severity of noncritical patients with COVID-19.

Turner Syndrome With Isochromosome Structural Abnormalities: A Case Report

Turner syndrome (TS) is the most common cause of short stature and delayed puberty in females. Approximately half of the patients have the classic form with a genotype of 45,XO, one-fourth of patients have different mosaic forms, and the remaining one-fourth have structural abnormalities on the X chromosome. Among the structural abnormalities, the most common is isochromosome Xq. Females with structural variants of TS can present with delayed menarche, amenorrhea, and infertility rather than classic manifestations of TS. This study describes two rare variants of TS. One was a structural abnormality on the X chromosome, 46X,iso(Xq), and the other involves a mosaic variety of TS, including isochromosome X in the form of 45,XO/46X,iso(Xq). Both patients presented with short stature and secondary amenorrhea without classic manifestations of TS. In TS with or without mosaicism, the frequency of isochromosomes is reported to be about 15% to 18%. Owing to the absence of classical manifestations of TS, diagnosis may be delayed or missed. Therefore, females of short stature with secondary amenorrhea should be evaluated for rare variants of TS by chromosomal analysis.

Role of antimullarian hormone in the diagnosis of sonographically inconclusive polycystic ovary syndrome

Antimullarian hormone (AMH) is found to be a vital tool for the diagnosis of polycystic ovary syndrome (PCOS). AMH may help in the diagnosis of sonographically inconclusive cases of PCOS. This study measured the AMH level in PCOS to assess its impacts on the diagnosis of the syndrome. This cross-sectional study included 160 newly diagnosed females with PCOS who were diagnosed using a modified revised Rotterdam criteria. Fasting blood was collected to measure AMH by enzyme-linked immunosorbent assay and other hormones [total testosterone, luteinizing hormone and follicle-stimulating hormone] were measured by chemiluminescent microparticle immunoassay. Ovarian USG was done in the follicular phase of the menstrual cycle. Serum AMH≥ 3.5 ng/mL and ovarian volume >10 mL was considered as a combined marker of polycystic ovary (PCO). USG-PCO criteria could detect 84.38% PCO, whereas AMH-PCO criteria 67.5%. There was a lack of agreement between USG-PCO and AMH-PCO criteria [κ=-0.004] in PCOS. AMH-PCO criteria identified 68% of PCO patients undiagnosed by USG-PCO criteria [17/25]. Age [β=-0.172, p=0.040], systolic [β =-0.213, p=0.037] and diastolic blood pressure [β=0.301, p=0.004] had significant predictive associations with AMH by linear regression. AMH had a fair discriminating index for combined-PCO [AUC=0.824] in PCOS patients. In conclusion, AMH assessment can help detect PCOS patients who are inconclusively diagnosed by USG-PCO criteria. BSMMU J 2022; 15(2): 65-69

Localization and management of mediastinal parathyroid adenoma – a case report

Ectopic parathyroid adenoma sometimes poses diagnostic challenge and can be a cause of persistent and recurrent primary hyperparathyroidism. Anterior mediastinum is one of the locations for ectopic parathyroid adenoma. Surgical excision is the only cure and for successful surgery, pre-operative localization is crucial. Chance of failed surgery is being increased without prior localization of the ectopic gland. The combination of single photon emission computed tomography (SPECT) and computed tomography (CT) has got high sensitivity for accurate localization of ectopic parathyroid. On the other hand, with accurate localization surgical outcome is excellent. Here we report, successful localization and management of a case of primary hyperparathyroidism due to adenoma in anterior mediastinum in 47-year-old man. IMC J Med Sci 2022; 16(2): 003. DOI: https://doi.org/10.55010/imcjms.16.013 *Correspondence: Dr. Nusrat Sultana, Room no-1620, Block-D, 15th floor, Department of Endocrinology, Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh. Email: nusrat_sultana@bsmmu.edu.bd

Effects of metformin on polycystic ovary syndrome: a randomized, double-blind, placebo-controlled study

Background and objectives: Metformin improves manifestations of polycystic ovary syndrome (PCOS) by reducing insulin resistance. The objective of this study was to determine how metformin, in combination with lifestyle changes, affects the clinical manifestations of PCOS. Materials and Methods: Patients with PCOS attending the outpatient of a tertiary care hospital were enrolled in the study. Revised Rotterdam Consensus 2003 criteria were used to diagnose cases of PCOS. Clinical information, anthropometric measurement, serum progesterone and polycystic ovarian morphology (PCOM) of each subject were recorded in a prescribed data sheet at baseline and after a period of nine months. Randomized placebo controlled double blind design was used to assign participants in respective groups. Participants were randomly assigned to receive 9-month course of either metformin (1500 mg/day) or placebo. Both groups were advised regarding schedule of lifestyle modification. Outcome variables were clinical manifestations related to metabolic, reproductive and androgenic status of PCOS. Results: Out of 80 enrolled PCOS cases, 49 completed the study (metformin=26, placebo=23). The mean age of the study participants of metformin and placebo groups was 23.52±5.18 and 22.09±3.58 years respectively (p=0.262). Menstrual cycle significantly improved in both the study groups (before vs. after - metformin: 19.2% vs. 76.9%, p=0.003; placebo: 19.2% vs. 47.8%, p=0.02) after 9 months, but compared to placebo group no such significant (p=0.12) improvement occurred in metformin group. Severity of hirsutism, presence of acne, serum progesterone level and ovulatory status improved significantly in both groups after completion of the study. Except acanthosis nigricans, other metabolic manifestations did not significantly improve in metformin compared to placebo group after the intervention. While comparing the percentage changes, body mass index (BMI) and waist circumference (WC) reduced significantly in metformin than placebo group (BMI in kg/m2- metformin vs. placebo: -3.63±8.22 vs. +1.42±6.67, p= 0.024; WC in cm - 2.81±7.74 vs. +1.68±7.89, p= 0.05). No significant adverse event was observed in metformin group. Conclusion: Metformin, in conjunction with lifestyle modifications, has favorable impacts on clinical manifestations of PCOS. Ibrahim Med. Coll. J. 2021; 15(2): 1-12

Association of altered thyroid function and prolactin level in polycystic ovarian syndrome

Polycystic ovarian syndrome (PCOS) is a common disorder for female with fertile age. Along with other clinical and biochemical manifestations, thyroid function and prolactin level may be altered in patients with PCOS. This study aimed to evaluate the clinical and biochemical status, as well as alteration of thyroid stimulating hormone (TSH), prolactin (PRL) level in patients with PCOS. Present study comprised of 100 diagnosed PCOS patients according to revised Rotterdem Consensus criteria. All patients were studied for serum testosterone, LH (lutenizing hormone), FSH (follicle stimulating hormone), blood glucose, lipid profile as well as TSH, FT4 (free thyroxin) and prolactin level. Out of 100 PCOS patients 97 had hirsutism, 64 had acanthosis nigricans, where menstrual irregularities were in 94 patients. Diastolic blood pressure (74±1.1 vs. 77±0.9, mmHg; p=0.017), total cholesterol (163±5.3 vs. 193±6.2 mg/dl; p<0.001), low density lipoprotein (LDL, 104±3.7 vs. 124±4.9 mg/dl; p=0.002) and frequency of acanthosis (25% vs. 75%; p<0.001) were significantly higher among the patients having BMI>25 Kg/m2 than those of have ? 25 Kg/m2. Among the fertile women (n=53), 47% had primary and 41.5% had secondary infertility; whereas of the total patients, 21% had altered thyroid function and 6.1% had raised prolactin (PRL, ng/ml) level. Differences of TSH (4.1±3.6 vs. 3.5±6.8, mIU/L; p=0.725) was not significant; whereas level of PRL (13.87±6.9vs. 9.4±5.2 ng/ml; p=0.018) was significantly higher in the group of primary infertility. Hirsutism, menstrual disturbance and acanthosis were very common in PCOS. Both primary and secondary sterility were also commonly observed and PRL was higher in primary infertility. About one fifth of PCOS had altered thyroid function.Bangladesh Med J. 2016 Jan; 45 (1): 1-5

Beyond pregnancy--the neglected burden of mortality in young women of reproductive age in Bangladesh: a prospective cohort study

OBJECTIVE

To describe proportionate mortality and causes of death unrelated to pregnancy.

DESIGN

Prospective cohort study.

SETTING

Rural northwest Bangladesh.

POPULATION

A cohort of 133,617 married women of reproductive age.

METHODS

Verbal autopsies were conducted for women who died whilst under surveillance in the cohort trial. Physician-assigned causes of death based on verbal autopsies were used to categorise deaths.

MAIN OUTCOME MEASURES

The proportion of deaths due to non-communicable diseases, infectious diseases, injury or pregnancy.

RESULTS

Of the 1107 deaths occurring among women between 2001 and 2007, 48% were attributed to non-communicable diseases, 22% to pregnancy, 17% to infections, 9% to injury and 4% to other causes.

CONCLUSIONS

Although focus on pregnancy-related mortality remains important, more attention is warranted on non-communicable diseases among women of reproductive age.

Assessment of occupational and patient dose from diagnostic and therapeutic radiation exposure using thermoluminescent dosimetry

Radiation doses of occupational personnel exposed from diagnostic x rays, therapeutic installations, and patients were measured using thermoluminescent dosimeters. The monthly occupational doses from diagnostic x ray ranged from 0.1076 mSv to 0.5774 mSv, and those from therapeutic treatment ranged from 0.365 mSv to 0.657 mSv, which is within the dose limit recommended by ICRP 60. The patient organ doses were evaluated and found to range from 0.0615 mSv s(-1) to 2.8823 mSv s(-1) for gonad, 0.3676 mSv s(-1) to 2.1088 mSv s(-1) for thyroid, and 0.00972 mSv s(-1) to 4.01 mSv s(-1) for eyes.

Observations questioning a protective role for breast-feeding in severe rotavirus diarrhea

To investigate whether breast-feeding protects children against rotavirus diarrhea (RVD), we compared rates of breast-feeding by age and enteric pathogens among 2,276 children with diarrhea 0-4 years of age who attended a diarrhea hospital in Bangladesh. Infants 0-5 months were less likely to be breast-fed than children 6-11 months of age suggesting that some protection against diarrhea with all agents was associated with early breast-feeding. In every age group studied, breast-feeding was more common among children with RVD than among children with non-RVD whereas it was less common among children with cholera and shigellosis. Twenty percent of breast milks consumed by infants less than 1 year of age had high levels of neutralizing activity (greater than or equal to 320) to the Wa strain of rotavirus but this activity did not appear to be protective since the 30 infants with RVD consumed milk which had titers that did not differ significantly from those consumed by 44 infants with diarrhea of other cause. Despite the prolonged breast-feeding which is common in Bangladesh, the mean age of hospitalization with RVD is approximately the same as in countries where the duration of breast-feeding is quite short. None of these 3 independent observations support a protective role for breast-feeding against rotavirus diarrhea after the first months of life.

Breast feeding as a determinant of severity in shigellosis. Evidence for protection throughout the first three years of life in Bangladeshi children

Little is known about the effect of breast feeding upon the severity of illness due to specific diarrheal pathogens. Using a systematically sampled and evaluated population of children aged less than 3 years, who attended a diarrheal disease hospital in Bangladesh, the authors performed a case-control study that assessed whether breast feeding reduces the severity of illness in shigellosis. From 540 children presenting with shigellosis between 1980-1982, they created a group of cases (n = 53) with severe illness and controls (n = 487) with non-severe illness. Overall, the odds ratio relating breast feeding to the severity of shigellosis (0.49, p = 0.01) suggested a substantial mitigating effect of breast feeding upon clinical severity. The high degree of protection against severe shigellosis was evident for breast-fed children up to 35 months of age, as well as for children at high risk for death because of severe malnutrition or measles. Because shigellosis continues to account for substantial morbidity and mortality in children in developing countries, the results support prolonged breast feeding in these settings.

Changing pattern of resistant Shiga bacillus (Shigella dysenteriae type 1) and Shigella flexneri in Bangladesh

Shigella dysenteriae type 1 (Shiga bacillus) has made a dramatic comeback in Bangladesh after 10 years when Shigella flexneri was the dominant serogroup. Whereas S. flexneri showed little increase in resistance to the commonly used antimicrobial agents--namely, trimethoprim-sulfamethoxazole (TMP-SMX) and ampicillin-over the years, S. dysenteriae type 1 underwent rapid changes with regard to sensitivity pattern during the last two years. The first TMP-SMX-resistant strain of S. dysenteriae type 1 was detected in September 1982; however, by mid-1984 most strains were resistant while retaining sensitivity to ampicillin. During this period, the ratio of S. flexneri to S. dysenteriae type 1 narrowed from 0.15 to 1. Such propagation of high resistance to TMP-SMX might have been due to widespread use of the drug imported into the country in large quantities. Resistance to ampicillin is increasing rapidly, particularly in S. dysenteriae type 1.

Value of stool examination in patients with diarrhoea

Findings of stool examinations in 1593 patients with diarrhoea due to a single enteric pathogen--enterotoxigenic Escherichia coli rotavirus, Shigella, Campylobacter jejuni, Vibrio cholerae 0:1, Entamoeba histolytica, or Giardia lamblia--were reviewed to determine how well they predicted the agent associated with the diarrhoea. Specimens were examined visually for blood and mucus, tested for pH, and examined under a microscope for the presence of red and white blood cells, parasites, and stool fat. Although visible blood was more common in specimens from patients infected with Shigella (51%) and Ent histolytica (39%) than in those from patients infected with other agents (6%; p less than 0.01), patients infected with Shigella were most likely to have numerous faecal leucocytes (greater than 50/high power field: 39% v 8% of all patients and 7% of patients infected with Ent histolytica, p less than 0.01 in both cases). Patients infected with enterotoxigenic E coli, rotavirus, V cholerae 0:1, or C jejuni had loose stools with fewer red or white cells. Patients infected with rotavirus and C jejuni were more likely to have acid stools with 3 to 4+ fat, but these findings were related to young age and breast feeding. Stool examination is most useful in establishing a diagnosis of dysentery and in helping to distinguish between patients infected with Shigella and Ent histolytica; it is of limited usefulness in discriminating between pathogens causing watery diarrhoea.

Enteric fever in patients admitted to a diarrhoeal disease hospital in Bangladesh

The hospital records of 62 patients with blood culture-proven enteric fever admitted to the Dacca Hospital of the International Centre for Diarrhoeal Disease Research, Bangladesh, over a one-year period were reviewed. Older children and young adults had the highest age-specific rates of disease. The clinical, epidemiological and laboratory features of patients with enteric fever were compared with similar information from patients in hospital for cholera and shigellosis. Patients with enteric fever had a significantly longer prodrome of illness and were more likely to have fever than patients in the other groups. Our hospital cares primarily for patients with diarrhoeal diseases and while 94% of enteric fever patients had diarrhoea, only 5% had the recognized diarrhoeal pathogens Shigella or Vibrio cholerae identified, compared to 25% of the total hospital in-patient group, suggesting that Salmonella typhi itself may be a cause of diarrhoea. Antibiotic resistance patterns of S. typhi isolates were reviewed, and one isolate was found to be multiply antibiotic resistant. The advent of an effective oral typhoid vaccine makes further work on the epidemiology of enteric fever in endemic areas such as Bangladesh a high priority.

Surveillance of patients attending a diarrhoeal disease hospital in Bangladesh

In October 1979 a surveillance system was set up at the International Centre for Diarrhoeal Disease Research, Bangladesh, Hospital at Dacca to study a 4% systematic sample of the 100 000 patients with diarrhoea who come to the hospital for care each year. From December 1979 to November 1980 inclusive, 3550 patients were studied. A recognised pathogenic organism was identified for 66% of patients screened for all pathogens, one-third of whom had a mixed infection with two or more agents. Enterotoxigenic Escherichia coli was the most common enteropathogen detected in all age groups (detection rate 20%), followed by rotavirus (19%), Campylobacter jejuni (14%), and Shigella (12%). Infants and young children (up to 5 years) were most often infected with rotavirus, enterotoxigenic E coli, and C jejuni and older children (5-14 years) had more infections with enterotoxigenic E coli, Shigella, and E histolytica. Surveillance has helped to define the range of disease among patients attending the Dacca Hospital. Sixty-five per cent of patients complained of watery diarrhoea, a presentation that was significantly more common in patients with Vibrio cholerae 0:1 (91%), enterotoxigenic E coli (78%), rotavirus (77%), and C jejuni (71%) than in all patients studied. Dysentery, defined as a history of diarrhoea with blood, was the presenting complaint of 20% of all patients but 55% of those with Shigella. Only patients with V cholerae 0:1 and enterotoxigenic E coli were at increased risk for severe dehydration. In addition surveillance has been used to identify areas where patient care can be improved and to generate new ideas for research.

Epidemiologic and clinical features of patients infected with Shigella who attended a diarrheal disease hospital in Bangladesh

The epidemiologic and clinical characteristics of 412 patients infected with Shigella from a systematic sample of approximately 100,000 patients attending Dacca Hospital, International Centre for Diarrhoeal Disease Research, Bangladesh, between December 1, 1979, and November 30, 1980, were reviewed. Shigella was isolated from 11.6% of the 3,550 patients in the sample and was the second most common isolate in patients over two years old. Two clinical presentations of shigellosis were found: (I) watery diarrhea occurring in younger children and associated with a shorter duration of illness and with more vomiting and dehydration and (2) dysentery with stool blood and abdominal pain. These different presentations may reflect two mechanisms in the pathogenesis of shigellosis or different stages of the disease. The most useful signs and symptoms for the diagnosis of shigellosis were stool with blood and abdominal pain in all patients and the absence of watery diarrhea and vomiting in patients over one year old. Simple visual inspection of stool for blood correctly identified 44% of all patients infected with Shigella.