Pellagra

Pellagra is a nutritional deficiency disorder caused primarily by lack of niacin (vitamin B3 / nicotinic acid) or deficiency of its precursor tryptophan. It classically presents with the three Ds:

• Dermatitis

• Diarrhea

• Dementia

If untreated → may progress to death (the 4th D).

The disease commonly occurs in populations dependent on maize-based diets without adequate protein supplementation, chronic alcoholism, malabsorption, and chronic illness.

Pathophysiology

Niacin is required for formation of NAD and NADP, essential coenzymes in cellular energy metabolism.

Deficiency leads to:

• Impaired cellular repair

• Photosensitive skin damage

• Gastrointestinal mucosal atrophy

• Neuronal degeneration

Risk Factors

• Poor diet (maize-based diet without protein)

• Severe malnutrition

• Chronic alcoholism

• Chronic diarrhea or malabsorption

• HIV infection

• Tuberculosis

• Carcinoid syndrome (tryptophan depletion)

• Prolonged use of isoniazid

• Poverty and food insecurity

Signs & Symptoms

Skin (Dermatitis — hallmark)

• Casal’s necklace (hyper-pigmented scaling rash around neck)

• Hyper-pigmented scaly lesions on sun-exposed areas

• Symmetrical lesions

• Thickened, rough skin

• Burning sensation after sun exposure

• Later → cracked, fissured, painful skin

Common sites:

• Neck

• Face

• Hands

• Forearms

• Feet

Gastrointestinal (Diarrhea)

• Chronic diarrhea

• Glossitis (beefy red tongue)

• Angular stomatitis

• Abdominal pain

• Nausea and vomiting

• Malnutrition and weight loss

Neurological (Dementia)

• Irritability

• Depression

• Confusion

• Memory loss

• Psychosis

• Peripheral neuropathy (late)

Diagnostic Criteria

Clinical diagnosis based on:

• Casal’s necklace — hyperpigmented scaling on neck

• Hyperpigmented scaly lesions on sun-exposed areas

• Associated diarrhea and neuropsychiatric features

Investigations

Usually clinical diagnosis, but supportive tests may include:

• Full blood count → anemia

• Serum albumin → malnutrition

• Electrolytes → dehydration from diarrhea

• HIV testing (high association)

• Response to niacin therapy confirms diagnosis

Treatment

Non-Pharmacological Treatment

• High-protein diet (meat, fish, eggs, beans, groundnuts)

• Balanced diet rich in vitamins

• Nutrition rehabilitation

• Sun protection (protective clothing)

• Treat underlying cause (malabsorption, alcoholism, infection)

Pharmacological Treatment

Adults

• Nicotinamide 500 mg orally once daily for 4 weeks or until healing

Children

• Nicotinamide 5 mg/kg/day orally for 4 weeks or until healing

Additional supportive therapy

• Multivitamin supplementation

• Rehydration if diarrhea present

• Treat secondary infections

Diet recommendation

• Protein-rich foods: meat, beans, groundnuts, milk

Complications

• Severe malnutrition

• Psychosis

• Permanent neurological impairment

• Sepsis from skin breakdown

• Death if untreated

Prevention

• Balanced diet containing adequate protein

• Food fortification programs

• Early treatment of malnutrition

• Nutrition education in vulnerable communities

• Screening high-risk patients (HIV, TB, alcohol dependence)

Prognosis

• Rapid improvement within days after treatment

• Skin lesions improve in 1–3 weeks

• Neurological recovery slower; may be incomplete if delayed