Fluorosis

Definition

Etiology / Cause

• Primary source: drinking water with fluoride concentration >1.5 mg/L (dental fluorosis) or 3-6 mg/L (skeletal fluorosis)
• At concentrations exceeding 10 mg/L, crippling fluorosis can occur
• Dietary factors: diets based on sorghum (jowar) promote higher retention of ingested fluoride compared to rice-based diets

Types / Clinical Manifestations

(a) Dental Fluorosis

• Occurs when excess fluoride is ingested during tooth calcification (first 7 years of life)
• Characterized by mottling of dental enamel (reported at levels >1.5 mg/L)
• Early sign: teeth lose their shiny appearance; chalk-white patches develop
• Progression: white patches become yellow, then brown or black
• Severe cases: loss of enamel gives a corroded appearance
• Most visible on the incisors of the upper jaw
• Almost entirely confined to permanent teeth and develops only during tooth formation

(b) Skeletal Fluorosis

• Associated with lifetime daily intake of 3.0-6.0 mg/L or more
• Heavy fluoride deposition in the skeleton
• Radiological features:
  • Osteosclerosis (particularly axial skeleton)
  • Enthesopathy with ossification of ligaments
  • Large spinal osteophytes and paraspinal ossification
  • Periosteal proliferation and degenerative changes
  • Paraspinal ossification may cause compression myelopathy
• Leads to permanent disability at high concentrations (>10 mg/L)

(c) Genu Valgum (Endemic Fluorosis variant)

• Characterized by genu valgum and osteoporosis of lower limbs
• Reported in Andhra Pradesh and Tamil Nadu
• Observed among people whose staple diet was sorghum (jowar)

Prevention / Control

1. Change water source: Find a new source with lower fluoride content (0.5-0.8 mg/L); surface water has lower fluoride than groundwater
2. Chemical defluoridation - Nalgonda Technique (developed by NEERI, Nagpur): Addition of lime and alum in sequence, followed by flocculation, sedimentation, and filtration
3. Avoid fluoride supplements in children drinking fluoridated water
4. Fluoride toothpaste is NOT recommended in endemic areas for children up to 6 years of age

National Programme for Prevention and Control of Fluorosis (NPPCF)

• Essential services: Referral services and IEC (Information, Education, Communication) activities in fluorosis-endemic districts
• Desirable: Clinical examination and diagnostic assessment for fluorosis cases, monitoring of community-level surveillance

• Park's Textbook of Preventive and Social Medicine, pp. 740
• Grainger & Allison's Diagnostic Radiology

Nutritional Anemias

Classification

1. Iron Deficiency Anemia (IDA)

Prevalence

Causes

• Chronic blood loss - most important cause in high-resource countries (GI bleeds from peptic ulcers, colon cancer, hemorrhoids; menorrhagia)
• Low dietary intake / poor bioavailability - most common in low-resource countries (vegetarian diets); also seen in infants fed exclusively milk, elderly
• Increased demand - pregnancy, infancy
• Malabsorption - celiac disease, gastritis, post-gastrectomy

Iron Metabolism Basis

• Normal body iron: ~2.5 g (women), 3.5 g (men); 80% in hemoglobin/myoglobin/enzymes
• Regulated by hepcidin (liver peptide) - negatively regulates ferroportin, controlling iron export from enterocytes
• Serum ferritin = best surrogate of iron stores
• In deficiency: stores depleted first → serum iron falls → transferrin rises → microcytic anemia develops

Pathogenesis of Microcytosis

Clinical Features

• Often mild and asymptomatic
• Weakness, listlessness, pallor
• Long-standing anemia: koilonychia (spoon-shaped nails), nail thinning/flattening
• Pica (compulsion to eat non-food substances such as dirt or clay) - characteristic neurobehavioral complication

Laboratory Findings

• Decreased hematocrit, MCV, MCH
• Low serum ferritin and serum iron
• Elevated total iron-binding capacity (TIBC)
• Low transferrin saturation
• Thrombocytosis (platelet count often elevated)
• Elevated erythropoietin

2. Megaloblastic Anemia (Vitamin B12 / Folate Deficiency)

Mechanism (Common to Both)

• Nuclear-cytoplasmic asynchrony
• Abnormally large erythroid precursors (megaloblasts)
• Ineffective hematopoiesis and pancytopenia

Morphology (Blood Smear)

• Macro-ovalocytes (large, oval red cells) - highly characteristic
• Hypersegmented neutrophils (5+ lobes instead of normal 3-4)
• Anisocytosis and poikilocytosis
• Low reticulocyte count
• Bone marrow: hypercellular with megaloblastic changes at all erythroid stages, giant metamyelocytes, abnormal megakaryocytes

(A) Vitamin B12 Deficiency - Pernicious Anemia

1. B12 released from food by pepsin → binds salivary haptocorrin
2. In duodenum, released from haptocorrin by pancreatic proteases → binds intrinsic factor (IF) secreted by gastric parietal cells
3. B12-IF complex → binds cubilin receptor on ileal epithelial cells → endocytosed
4. Released into plasma bound to transcobalamin II → delivered to liver and bone marrow

• Decreased intake: strict vegetarianism / vegan diet
• Pernicious anemia (most important): autoimmune gastritis destroys parietal cells → no intrinsic factor
• Gastrectomy, ileal resection, ileitis
• Fish tapeworm (Diphyllobothrium latum) - competitive uptake
• Bacterial overgrowth in blind loops

• B12 (as methylcobalamin) converts homocysteine to methionine via methionine synthase
• In doing so, it liberates FH4 (tetrahydrofolate) from its "trapped" form (N5-methyl FH4)
• FH4 is required for dUMP → dTMP (DNA synthesis)
• B12 deficiency thus causes a functional folate deficiency

• B12 also required for methylmalonyl-CoA → succinyl-CoA (via adenosylcobalamin)
• Deficiency leads to elevated methylmalonic acid → demyelination of posterior and lateral columns of spinal cord
• Not improved by folate (unlike the anemia)

(B) Folate Deficiency Anemia

• Inadequate dietary intake (most common) - poor diet, alcoholism, infancy
• Increased requirement: pregnancy, infancy, hemolytic anemias, disseminated cancer
• Malabsorption: celiac disease, tropical sprue
• Drugs: anticonvulsants (phenytoin), oral contraceptives, methotrexate (folate antagonist)
• Increased loss: hemodialysis

Summary Table

• Robbins, Cotran & Kumar - Pathologic Basis of Disease, pp. 608-612
• Robbins & Kumar Basic Pathology, pp. 393-395
• Basic Medical Biochemistry - A Clinical Approach (6e), p. 1537

Balanced Diet

Definition

• Maintaining health, vitality, and general well-being
• Making a small provision for extra nutrients to withstand short periods of leanness

Components of a Balanced Diet

Principles of Constructing a Balanced Diet

The Food Guide Pyramid

Recommended Dietary Allowances (RDA) for Indians - 2020

Special Dietary Needs

• Growth (children, adolescents) - increased protein, calcium, iron
• Pregnancy - extra protein (+9.5 g in 2nd trimester, +22 g in 3rd trimester), iron (27 mg/day), folate, iodine
• Lactation - increased caloric intake, calcium, vitamins
• Physical activity - increased energy and B vitamins
• Medical disorders - e.g., diabetics need controlled carbohydrates; renal patients need protein restriction

Characteristics of a Good Balanced Diet (Summary - "ABCDE")

• Adequate - meets all nutrient requirements
• Balanced - correct proportions of macronutrients and micronutrients
• Calorie-appropriate - energy intake matches energy expenditure
• Diverse - variety of foods from all food groups
• Economical - affordable and culturally acceptable

Lathyrism

Definition

• Neurolathyrism (in humans) - affects the nervous system; characterized by spastic paralysis of the lower limbs
• Osteolathyrism / Odoratism (in animals) - pathological changes occur in bones, resulting in skeletal deformities

The Causative Pulse - Lathyrus sativus

• Commonly called "Khesari dhal" (also: Teora dhal, Lak dhal, Batra, Gharas, Matra)
• Seeds have a characteristic triangular shape and grey colour
• When dehusked, resembles red gram or Bengal gram dhal
• A good source of protein, but contains a neurotoxin
• Eaten mainly by poor agricultural labourers because it is relatively cheap
• A drought-resistant, hardy crop that survives when other crops fail - hence consumed during famines
• Diets containing >30% Khesari dhal over 2-6 months result in neurolathyrism

The Toxin

• Identified as Beta-Oxalyl Amino Alanine (BOAA) - also written as beta-N-oxalamino-L-alanine
• Isolated in crystalline form; is water soluble (important for detoxification)
• Acts as a neuroexcitatory amino acid (excitotoxin) at glutamate receptors
• There is a blood-brain barrier to this toxin - the pulse must be eaten in large quantities over at least 2 months for the toxin to overcome this barrier
• BOAA induces corticospinal dysfunction, as demonstrated in primate models

Epidemiology / The Problem

• Endemic in parts of Madhya Pradesh, Uttar Pradesh, Bihar, Orissa, and also reported in Maharashtra, West Bengal, Rajasthan, Assam, Gujarat
• Historical burden: Rewa and Satna districts of MP alone had 25,000 and 32,000 cases respectively at one time
• Also reported in Spain and Algeria
• Fresh outbreaks have declined due to shifting agronomical practices
• Similar disease: Konzo (Africa) - acute spastic paraplegia due to cyanide-like compounds in cassava flour

Clinical Features

Stages of Neurolathyrism

Other Neurological Features (from Adams & Victor)

• Pain, paresthesias, numbness in legs
• Frequency and urgency of micturition
• Erectile dysfunction, sphincteric spasms
• Coarse tremors and involuntary movements of upper extremities
• Symptoms are permanent but not progressive once established; patients live out normal lifespan

Neuropathology

• Loss of ascending and descending tracts in the spinal cord - particularly corticospinal and spinocerebellar tracts
• Loss of myelinated fibres in lateral and posterior columns
• Betz cells (upper motor neurons) disappear; anterior horn cells unaffected
• Gliosis and thickening of blood vessels in degenerated tracts

Interventions (Prevention and Control)

• 500-1000 mg of ascorbic acid daily for a week may help repair damage and prevent progression
• Protective effect demonstrated in guinea pigs and monkeys with lathyrogenic diets

• The Prevention of Food Adulteration Act in India has banned Lathyrus in all forms (whole, split, or flour)
• However, the ban is difficult to enforce in endemic states
• If consumption cannot be avoided, the dhal should not form more than 1/4 of total cereals and pulses per day

1. Steeping method - soak pulse in hot water for 2 hours, drain and discard soak water, wash again, dry in sun. Drawback: loss of vitamins and minerals.
2. Parboiling - suitable for large-scale operations; soaking in lime water overnight followed by boiling also destroys toxin and trypsin inhibitors

• Certain strains of Lathyrus contain very low levels of toxin (~0.1%)
• Selective propagation and cultivation of low-toxin varieties may be the most effective long-term solution
• Low-toxin varieties available from the Indian Agricultural Research Institute (IARI), New Delhi

• Public education on the dangers of consuming Khesari dhal and the need for detoxification before consumption

• Ultimately, eradicating poverty and improving food security is the only way to root out lathyrism, as it is consumed primarily due to poverty and famine

• Park's Textbook of Preventive and Social Medicine, pp. 740-741
• Adams and Victor's Principles of Neurology (12th ed.), pp. 1273-1274

Difference Between Screening and Diagnostic Test

Definitions

Screening Test

"Screening is carried out in the hope that earlier diagnosis and subsequent treatment favourably alters the natural history of the disease." - Park's PSM

Diagnostic Test

• VDRL testing of patients with lesions suggestive of secondary syphilis
• Endocervical culture for N. gonorrhoeae

Key Differences at a Glance

Sensitivity and Specificity in Context

• Sensitivity = a / (a+c) × 100 → ability to detect true positives
• Specificity = d / (b+d) × 100 → ability to exclude true negatives
• Positive Predictive Value (PPV) = a / (a+b) × 100
• Negative Predictive Value (NPV) = d / (c+d) × 100

Lead Time

Important Concept: Case-Finding (an intermediate category)

Summary Statement

The distinction between screening, case-finding, and diagnosis should be clear-cut, but it is often blurred by the multiplicity of tests used. The same test (e.g., VDRL) may be used in different contexts - as a screening test in premarital screening, as a case-finding test in antenatal care, and as a diagnostic test in a patient with skin lesions of secondary syphilis. In evaluating a test, one must always consider whether it is being used for screening or diagnosis.

ESI (Employees' State Insurance) Benefits

Overview

Finance / Contributions

• Employees earning below Rs. 176/day are exempted from payment
• Coverage extended to employees earning up to Rs. 21,000/month

Benefits to Employees

1. Medical Benefit

1. Out-patient care
2. Supply of drugs and dressings
3. Specialist services in all branches of medicine
4. Pathological and radiological investigations
5. Domiciliary services
6. Antenatal, natal and postnatal services
7. Immunization services
8. Family planning services
9. Emergency services
10. Ambulance services
11. Health education
12. In-patient treatment

• Dentures, spectacles, and hearing aids - provided free for those incapacitated due to employment injury
• Artificial limbs - provided free to those who lose limbs in employment injury
• Special appliances (hernia belts, walking callipers, surgical boots, spinal braces) as prescribed

2. Sickness Benefit

• Periodical cash payment at about 70% of average daily wages
• Payable for a maximum of 91 days in any continuous period of 365 days
• Must be certified by an Insurance Medical Officer/Practitioner
• The employee cannot be dismissed by employer during the period of sickness

• For insured persons with 34 specified long-term diseases, benefit is extended for up to 2 years (if employed continuously for 2 years)
• Diseases include: TB, leprosy, AIDS, malignant diseases, diabetes with complications, neurological disorders (hemiplegia, paraplegia, Parkinson's, etc.), cardiovascular diseases (CAD, CHF, cardiomyopathies), COPD, cirrhosis, chronic renal failure, schizophrenia, MDP, Burger's/Raynaud's disease, major burns, etc.

• Payable for sterilisation operations at double the standard benefit rate (= full wages)
• Females: 14 days (tubectomy); Males: 7 days (vasectomy)

3. Maternity Benefit

• Rate: approximately full wages
• Confinement expenses: Rs. 7,500 per confinement

4. Disablement Benefit

5. Dependant's Benefit

• Payable to dependants of an insured person who dies due to employment injury
• Pension at 90% of wages, shared among dependants in fixed ratio, on monthly basis
• Eligible son/daughter receives benefit up to age 18 (withdrawn on daughter's marriage)

6. Funeral Expenses

• Lump sum cash payment on death of insured person towards funeral expenses
• Amount: up to Rs. 15,000/-

7. Rehabilitation Allowance

• On monthly payment of Rs. 10, the insured person and family continue to receive medical treatment after permanent disablement or retirement

Rajiv Gandhi Shramik Kalyan Yojana (Unemployment Benefit)

• Eligibility: At least 5 years of insurable employment
• Benefit: Unemployment allowance for up to 6 months (in one or multiple spells, min. 1 month each)
• Rate: Standard benefit rate under ESI (Central) Rules, 1950

Benefits to Employers

1. Exemption from the Workmen's Compensation Act, 1923
2. Exemption from the Maternity Benefit Act, 1961
3. Exemption from providing medical allowance/care to employees
4. Income Tax rebate on contribution deposited in ESI Account
5. Assurance of a healthy, productive workforce