Whipple's Disease

Whipple's disease is a rare systemic infection caused by Tropheryma whipplei, an environmental gram-positive actinobacterium endemic worldwide. The disease predominantly affects middle-aged Caucasian males (male:female ratio approximately 4:1) and has a predilection for the gastrointestinal tract, joints, heart, and central nervous system. The interval between onset of arthralgia and diagnosis may span decades.

Classic Tetrad

The hallmark clinical presentation is characterised by four cardinal features, though not all may be present simultaneously:

• Arthralgia / arthritis: The most common presenting feature, occurring in >80% of cases. Typically a migratory, non-erosive, non-deforming polyarthralgia of large joints (knees, wrists, ankles). Arthritis may precede gastrointestinal symptoms by 5–10 years or longer and often responds transiently to NSAIDs.
• Weight loss: Progressive and often profound, reflecting malabsorption secondary to small bowel mucosal infiltration with PAS-positive macrophages.
• Diarrhoea: Chronic watery diarrhoea, occasionally steatorrhoeic, secondary to mucosal lymphatic obstruction and villous blunting. May be intermittent in early disease.
• Abdominal pain: Diffuse, cramping, and often postprandial; associated with mesenteric lymphadenopathy and intestinal wall thickening.

Extra-Intestinal Manifestations

T. whipplei can disseminate haematogenously to virtually any organ system. Extra-intestinal disease may occur in the absence of classic GI features.

Central Nervous System (CNS) Involvement

CNS Whipple's disease occurs in 10–40% of cases and portends a worse prognosis if not recognised early. Manifestations include:

• Cognitive and psychiatric change: Progressive dementia, personality change, memory impairment, confusion, and psychosis. These may be the sole presenting features in isolated CNS disease.
• Oculomasticatory myorhythmia: A pathognomonic movement disorder consisting of convergent–divergent pendular nystagmus synchronous with rhythmic contractions of the jaw (masticatory muscles). When present, this is essentially diagnostic of Whipple's disease.
• Supranuclear gaze palsy: Vertical gaze palsy mimicking progressive supranuclear palsy. This should prompt investigation for Whipple's disease, especially in younger patients.
• Other CNS features include hypothalamic dysfunction (polyuria, polydipsia, insomnia), ataxia, myoclonus, seizures, and cranial nerve palsies.

Culture-Negative Endocarditis

T. whipplei is an increasingly recognised cause of culture-negative infective endocarditis. Presentation may include fever, new or changing murmur, embolic phenomena, and heart failure. Diagnosis is typically made by valve tissue PCR. All patients presenting with culture-negative endocarditis should be considered for T. whipplei testing.

Ocular Involvement — Uveitis

Uveitis may be anterior, posterior, or pan-uveitis and can be the presenting feature. It may occur with or without concurrent systemic disease. Recurrent or refractory uveitis in middle-aged men should raise suspicion.

Lymphadenopathy

Generalised peripheral lymphadenopathy is common and may mimic lymphoma or other granulomatous diseases. Lymph node biopsy reveals PAS-positive macrophages. Mesenteric lymphadenopathy is particularly prominent and may be visible on CT imaging.

Other Manifestations

• Hyperpigmentation: Generalised skin darkening, particularly in sun-exposed areas.
• Seronegative polyarthritis: May mimic rheumatoid arthritis, reactive arthritis, or ankylosing spondylitis.
• Pleural/pericardial effusions: Due to lymphatic obstruction.
• Endocrine abnormalities: Adrenal insufficiency, hypogonadism from hypothalamic infiltration.

Diagnosis

Whipple's disease remains underdiagnosed due to its rarity and protean manifestations. A combination of histopathology, PCR, and clinical assessment is required for definitive diagnosis.

Histopathology — Duodenal Biopsy

• Gold standard: Oesophagogastroduodenoscopy (OGD) with biopsy of the second part of the duodenum.
• PAS staining: Duodenal mucosal biopsies reveal lamina propria infiltration with large, foamy macrophages containing PAS-positive, diastase-resistant intracellular granules. This is the histological hallmark of Whipple's disease.
• Villous blunting and lymphatic dilation may also be seen on haematoxylin and eosin staining.
• Histology alone may be insufficient in isolated CNS disease, where duodenal biopsies can be normal. PAS staining of CSF or brain biopsy tissue may be diagnostic.

T. whipplei PCR

• Tissue PCR: Should be performed on duodenal biopsy specimens to confirm T. whipplei DNA. This is particularly valuable when PAS staining is equivocal or when quantifying treatment response.
• CSF PCR: Mandatory in all patients at diagnosis, even if neurological symptoms are absent. Subclinical CNS involvement is present in a significant proportion of patients.
• Blood PCR: May be positive during active disease but has lower sensitivity than tissue PCR. Useful for monitoring treatment response.
• PCR testing is available at reference laboratories in Australia including state public health laboratories. MBS item 69496 (nucleic acid amplification) may be applicable.

CSF Examination

• Indication: CSF examination with cell count, protein, glucose, cytology, and T. whipplei PCR must be performed in every patient with confirmed or suspected Whipple's disease.
• Findings: Lymphocytic pleocytosis, elevated protein, and PAS-positive macrophages on cytospin preparation. PCR is the most sensitive CSF test.
• A normal CSF does not exclude future CNS relapse; long-term monitoring is required.

Treatment

Treatment is prolonged and must not be discontinued prematurely. The regimen consists of an intravenous induction phase followed by long-term oral maintenance therapy.

Induction Phase (2–4 Weeks)

Maintenance Phase (12 Months Minimum)

Adjunctive Therapy for CNS Disease

• Patients with proven or suspected CNS involvement should receive extended IV induction (4 weeks) followed by oral maintenance with TMP-SMX.
• If CSF PCR remains positive after initial IV therapy, consider adding hydroxychloroquine 200 mg PO BD to improve CNS drug penetration.
• Doxycycline 100 mg PO BD may be substituted or added as part of combination maintenance therapy for CNS disease.
• CNS involvement warrants a longer course of treatment — typically 12–24 months — guided by serial CSF PCR results.

Monitoring for Relapse and Immune Reconstitution Inflammatory Syndrome (IRIS)

Relapse Surveillance

Relapse occurs in up to 30% of patients and is most commonly due to premature discontinuation of therapy or inadequate CNS penetration.

• Clinical monitoring: Symptom review (arthralgia, diarrhoea, weight change, cognitive function) at 3-monthly intervals during therapy and for 2 years post-treatment.
• Histological monitoring: Repeat duodenal biopsy at 6 months, 12 months (end of therapy), and 24 months. Persistent PAS-positive macrophages or positive PCR indicates incomplete clearance.
• PCR monitoring: Tissue or blood PCR should be checked at 6 and 12 months. CSF PCR should be repeated at 12 months in patients with prior CNS involvement.
• Relapse management: Re-induction with IV ceftriaxone for 4 weeks followed by restart or modification of oral maintenance. Consider doxycycline-hydroxychloroquine combination if not already used.

Immune Reconstitution Inflammatory Syndrome (IRIS)

IRIS may occur after initiation of effective antibiotic therapy, particularly in patients who are immunosuppressed (e.g., concurrent corticosteroid use, HIV co-infection, biologic therapy). It is characterised by paradoxical worsening of symptoms due to an enhanced immune response to dying organisms.

• Features: New or worsening neurological symptoms (seizures, cognitive deterioration), fever, worsening lymphadenopathy, or new inflammatory lesions on imaging despite adequate antibiotic therapy.
• Management: Continue antibiotics; short course of corticosteroids (prednisolone 0.5–1 mg/kg/day, tapered over 2–4 weeks) may be considered in severe cases under infectious diseases supervision.
• Distinguish from treatment failure: IRIS is a diagnosis of exclusion; repeat PCR to confirm organism clearance. Persistent positive PCR suggests treatment failure or resistance rather than IRIS.

Supportive Care

• Nutritional support: Dietitian involvement is essential for patients with significant malabsorption. Consider oral nutritional supplements, and in severe cases, parenteral nutrition during induction therapy.
• Vitamin and mineral replacement: Vitamin D (cholecalciferol 1,000–2,000 IU daily), calcium (1,000–1,200 mg daily), iron (if iron deficiency anaemia present), vitamin B12, and folate supplementation as indicated by blood results.
• Bone health: DEXA scan should be considered due to chronic malabsorption and potential vitamin D deficiency. Bisphosphonate therapy if osteoporosis confirmed.
• Counselling and psychological support: Given the prolonged treatment course and potential for neurological sequelae, psychological support and patient education are important.

Management Timeline

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