on 18-Oct-2022 (Tue)

In 1907, George H Whipple described a 36-year-old clinician with "gradual loss of weight and strength, stools consisting chiefly of neutral fat and fatty acids, indefinite abdominal signs, and a peculiar multiple arthritis" [1]

Scientific understanding of the histology, immunology, and treatment of Whipple's disease has improved since the initial description, and the etiologic agent was identified in 1991.

T. whipplei is closely related to many other soil-borne actinomycetes [4,5].

The cause is now known to be Tropheryma whipplei (from the Greek "trophe," nourishment, and "eryma," barrier, in reference to the nutrient malabsorption characteristic of the disease), a discovery made upon application of a new technique for identifying microbes based upon the DNA sequence encoding their 16S ribosomal RNA

Whipple’s disease is caused by T. whipplei, a gram-positive bacillus related to Actinomycetes

Careful light and electron microscopy by numerous investigators between 1960 and 1992 subsequently identified a gram-positive, non-acid-fast, periodic acid-Schiff (PAS)-positive bacillus with a characteristic trilamellar plasma membrane surrounded by a cell wall.

Subsequently, a group from France was able to grow the organism in a human fibroblast cell line (HEL), subculture it successfully, demonstrate characteristic morphology by electron microscopy, and raise antibodies in mice that reacted with patient samples by immunofluorescence [8].

It appears to grow slowly (with a generation time estimated at four days in the report of successful cultivation from the CSF [10]).

The authors speculate that the organism may be transmitted by fecal-oral contamination; the fact that it is resistant to glutaraldehyde is problematic as this substance is widely used for disinfection.

A cell-free culture system for T. whipplei using defined culture medium was developed, based on the genome analysis of metabolic pathways [12]. However, it is unclear if the bacteria grown in cell-free culture medium are biologically and immunologically identical with those grown in cell culture.

T. whipplei, the agent of Whipple’s disease, is ubiquitous in the environment. The bacterium has been detected in sewage and is more prevalent in the fecal samples of sewage workers (12 to 26 percent) than the general population [13,14]

Classic, late-onset Whipple's disease is extremely rare. Between 1907 and 1987, there were 696 reported cases; the annual incidence since 1980 has been approximately 30 cases per year.

The disorder has a predilection for White males of European ancestry, suggesting an underlying genetic predisposition that leads to colonization of T. whipplei throughout the intestinal tract, lymphoreticular system, and central nervous system upon exposure to soil microbes [21]

The patient demographics of Whipple's disease are illustrated in a review of 664 patients that found [ 22]:

● 86 percent were male, with a mean age at diagnosis of 49 years

● 35 percent were farmers, and 66 percent had occupational exposure to soil or animals

Invasion or uptake of the bacillus is widespread throughout the body, including the intestinal epithelium, macrophages, capillary and lymphatic endothelium, colon, liver, brain, heart, lung, synovium, kidney, bone marrow, and skin. All of these sites show a remarkable lack of inflammatory response to the bacillus

In addition, the organism exerts no visible cytotoxic effects upon host cells, thereby allowing massive accumulation of T. whipplei at sites of infection.

The clinical manifestations of infection do not seem to be determined by pathogen specific factors; no correlation has been observed between variable genomic sequences of T. whipplei and clinical manifestations [27].

The organism is detectable in the saliva in up to 35 percent of healthy individuals and in the dental plaque and feces of healthy hosts [15-18], although it is rarely found in intestinal mucosa in the absence of histopathologic evidence of Whipple's disease [36].

IgG antibodies against T. whipplei are detectable in about 70 percent of healthy individuals [8], in accordance with the theory of frequent exposure to the potential pathogen.

Taken together, these observations suggest underlying host immune deficiency and possibly secondary immune downregulation induced by the bacterium. This likely results in accumulation of massive numbers of organisms within the intestinal tract, and subsequent impaired nutrient absorption. However, patients with Whipple's disease do not appear to be prone to opportunistic infections or to malignancy.

Classic Whipple’s disease is a multisystemic process characterized by joint symptoms, chronic diarrhea, malabsorption, and weight loss; many other organ systems can also be affected

The disease presents over time, with joint symptoms preceding the others by many years, so not all symptoms may be manifest at the time of presentation in affected individuals

Isolated involvement of other organs, most prominently the central nervous system (CNS) and heart valves, can also occur in the absence of the classic findings of Whipple’s disease. In one report of 52 patients, for example, the frequency of abnormalities before diagnosis was: articular (67 percent); gastrointestinal (15 percent); systemic (14 percent); and CNS (4 percent) [ 43]. Articular symptoms preceded the diagnosis of Whipple's disease by a mean of six years.

There have also been reports of Whipple's disease being unmasked or accelerated by immunosuppressive therapy, typically given for presumed rheumatic disease, in some cases with severe complications, such as sepsis or disseminated T. whipplei infection [44].

T. whipplei has also been associated with nonspecific febrile illness in rural West Africa [46,47]. In a study of 204 Senegalese patients with fever and negative malaria tests, T. whipplei bacteremia, as detected by PCR of the blood, was observed in 13 cases (6.4 percent). Most affected individuals were children; associated clinical symptoms included cough and sleep disturbances.

Asymptomatic carriage of T. whipplei has also been described, with detection of T. whipplei DNA in stool and saliva specimens from healthy individuals [15-20]. The prevalence depends on the geographic area. In Europe, the prevalence of the bacterium in fecal samples from the healthy adult population is estimated to be 1 to 11 percent [21].

Classic Whipple's disease — There are four cardinal clinical manifestations of late onset Whipple's disease [43]:

● Arthralgias

● Weight loss

● Diarrhea

● Abdominal pain

Joint symptoms — Joint symptoms are common, reported in up to 80 percent of patients [49-52]. These typically present as migratory arthralgias of the large joints, but there is no clearly characteristic presentation, and these can also manifest as a chronic, migratory oligoarthritis or polyarthritis. Fixed joint involvement with effusion occurs uncommonly. Joint destruction or deformities are rare. Peripheral joints are most commonly affected (knees, wrists, and ankles). Myalgias often accompany the joint symptoms.

GI symptoms and weight loss — Gastrointestinal symptoms generally occur later in the course of disease, after initial joint symptoms [50-52]. The main gastrointestinal manifestations are intermittent diarrhea with colicky abdominal pain. Watery diarrhea and steatorrhea have both been described, as have occult and gross gastrointestinal bleeding. This ultimately progresses to a severe wasting syndrome and weight loss. Late findings include abdominal distention due to ascites associated with chronic malabsorption.

Systemic – Many patients with Whipple's disease do not report fever; it has been reported in approximately 25 to 40 percent [50,52]. Lymphadenopathy, predominantly of the mesenteric and mediastinal nodes, has been reported in up to half of cases [49]; in occasional cases, this can raise suspicion for lymphoma.

Neurologic – Dementia and other central nervous system findings (such as supranuclear ophthalmoplegia, nystagmus, and myoclonus) occur more frequently in the later stages of the disease. These are discussed in further detail elsewhere. (See 'CNS disease' below.)

Cardiac – In addition to endocarditis, T. whipplei infection has also been associated with pericarditis and myocarditis.

Dermatologic – Skin hyperpigmentation can occur, reported in 40 to 45 percent [50,51]. The pathogenic mechanisms underlying this are uncertain but may be related to vitamin malabsorption [53].

Pulmonary – Symptoms or signs related to pleuropulmonary disease, including pleural effusion, chronic cough, interstitial-lung disease-like presentation, and pulmonary hypertension, have also been reported in or attributed to Whipple's disease [54-57]. In one study of 42 patients, pleuropulmonary symptoms were reported in 13 percent [43].

Laboratory findings – Laboratory abnormalities associated with chronic inflammation and malabsorption are common in patients with Whipple's disease. In a study that included 108 individuals with documented Whipple's disease, anemia was reported in 81 percent, and elevated leukocyte and platelet counts in 48 and 56 percent, respectively [52]. C-reactive protein was elevated in 69 percent. Other laboratory abnormalities include hypoalbuminemia and vitamin deficiency, including elevated prothrombin times secondary to vitamin K deficiency.

Other reported findings include ocular involvement (including uveitis and chorioretinitis) [58,59], prosthetic joint infection [60], and adrenal gland insufficiency [61].

Neurologic findings have been reported in 10 to 40 percent of patients with classic Whipple's disease. Isolated CNS infection with T. whipplei can rarely occur.

The incidence of CNS disease increases over time in an infected patient [ 29].

Most commonly, CNS involvement is asymptomatic and only diagnosed by PCR detection of T. whipplei in the CSF. Among patients with symptomatic CNS involvement, cognitive dysfunction, including dementia, other memory impairment, and confusion, is the most common abnormality [62].

Two findings, at least one of which is present in approximately 20 percent of such patients, are considered pathognomonic for Whipple's disease: oculomasticatory myorhythmia (continuous rhythmic movements of eye convergence with concurrent contractions of the masticatory muscles) and oculo-facial-skeletal myorhythmia [ 43,62,63]. These abnormalities are almost always accompanied by supranuclear vertical gaze palsy.

Cerebellar ataxia may be a more common feature of CNS disease than previously reported; in a retrospective review of 11 patients, cerebellar ataxia was present in five [64]. A variety of other neurologic findings have been described in case series, including myoclonus, hemiparesis, peripheral neuropathy, seizures, and upper motor neuron disorders [65]. Infection with T. whipplei may induce hypothalamic dysfunction.

Isolated neurologic involvement is rare and difficult to recognize. In one review of the literature that identified 20 patients with primary Whipple's disease of the brain, two clinical syndromes were identified [66]:

● Multifarious neurological symptoms and signs (eg, generalized seizures, ataxia, eye movement disorders, amnesic syndrome, syndrome of inappropriate anti-diuretic hormone secretion [SIADH], obstructive sleep apnea, insomnia, meningoencephalitis, hemiplegia, dementia, and others) with multiple enhancing lesions on CT or MRI (13 of 18 evaluable cases, 72 percent).

● Focal neurologic symptoms secondary to a solitary mass lesion (5 of 18 evaluable cases, 28 percent).

CSF investigation in patients with clinical CNS T. whipplei involvement is important. Usually, the CSF analysis is normal in asymptomatic patients. Patients with symptomatic CNS infection have a low to moderate pleocytosis (5 to 100 cells/microL) mostly made up of lymphocytes and monocytes or macrophages. Occasionally, periodic acid-Schiff (PAS)-positive macrophages can be identified in cytologic analysis of CSF. In addition, protein levels may be elevated and oligo-clonal bands may be present. In untreated patients, the CSF PCR for T. whipplei is positive when there is CNS involvement.

Endocarditis — Whipple endocarditis has been described in a small number of patients [8,43,67-70]. However, T. whipplei may be a more frequent cause of endocarditis than previously recognized. In a study of 255 patients whose explanted heart valves were positive for bacterial 16S rRNA gene amplification, T. whipplei was detected in 16 (6.3 percent) and was the most common cause of culture-negative endocarditis [71].

Endocarditis caused by T. whipplei may not be associated with the classical clinical presentation of Whipple's disease. Affected patients may have no clinical or histologic evidence of gastrointestinal disease or arthralgias [68-72].

In most cases, the diagnosis has been made by examination of the resected valve tissue [70]. The pathologic features include significant fibrosis, slight inflammation with foamy macrophages, lack of calcifications, and vegetations of intermediate size [70]. The prominent fibrosis with only slight inflammation suggests a slowly progressive infection, similar to that seen in Q fever and bartonellosis, which are other causes of culture-negative endocarditis [73]. T. whipplei can be detected in the resected valve by immunohistochemical analysis, which correlates with detection by culture or polymerase chain reaction.

Although Whipple's disease has a reputation as a great mimicker of many different illnesses, the difficulty in diagnosis is probably more a function of its rarity than its stealth.

It should be considered in all patients with the four cardinal manifestations (arthralgias, diarrhea, abdominal pain, and weight loss) after more common conditions have been excluded ( algorithm 1).

Suspicion of the diagnosis is more difficult in those patients (15 percent in one series) who do not develop gastrointestinal symptoms [ 43]. In particular, it should be a consideration in patients with rheumatoid factor-negative migratory polyarthritis that does not respond to immunosuppressive therapy

Other clinical syndromes that suggest the possible diagnosis of Whipple's disease include fever of unknown origin, chronic serositis, progressive central nervous system disease or early onset cognitive deficits with myoclonus or ophthalmoplegia, and generalized lymphadenopathy. Accompanying vitamin or iron deficiency anemia, hypoalbuminemia, and relative lymphopenia should increase the level of suspicion.

For patients with suspected Whipple's disease who have gastrointestinal symptoms, we start with upper endoscopy with biopsies of the small intestine for T. whipplei testing

For patients with suspected Whipple's disease who do not have gastrointestinal symptoms, specimens for T. whipplei testing are typically first taken from the relevant anatomical site

PCR of noninvasive specimens (urine, stool, or saliva) lacks sensitivity for diagnosis of localized Whipple's disease (non-classical); thus these invasive samples should be tested on the basis of clinical manifestations

Generally, the diagnosis of Whipple's disease can be made with PAS-positive staining on a small bowel biopsy or when two T. whipplei tests from gastrointestinal and/or extraintestinal specimens are positive.

All patients with a diagnosis of Whipple's disease also undergo lumbar puncture for PCR testing of the CSF to evaluate for central nervous system involvement, if this has not already been done.

In particular, among the disorders which should be excluded prior to making a diagnosis of Whipple's disease are:

● Inflammatory bowel disease with migratory polyarthropathy (see "Endoscopic diagnosis of inflammatory bowel disease in adults")

● Infectious causes of chronic diarrhea (see "Approach to the adult with chronic diarrhea in resource-abundant settings", section on 'Chronic infections')

● Connective tissue disease (see "Undifferentiated systemic rheumatic (connective tissue) diseases and overlap syndromes", section on 'General approach to the patient')

● Hyperthyroidism (see "Diagnosis of hyperthyroidism")

● HIV infection (see "Screening and diagnostic testing for HIV infection")

● Tuberculosis (see "Clinical manifestations, diagnosis, and treatment of miliary tuberculosis")

Testing of small bowel biopsy — Upper gastrointestinal endoscopy with biopsies of the small intestine is the diagnostic test of choice (algorithm 1) [43,63]. It is generally the first test performed for the evaluation of Whipple’s disease in patients with gastrointestinal symptoms, but it is also performed in patients with suspected extraintestinal Whipple’s disease to clarify or confirm the diagnosis.

A prothrombin time should be checked prior to biopsy because of the frequent occurrence of vitamin K malabsorption.

If these are unrevealing and the suspicion remains high, immunohistochemistry can be performed, but this test is generally available only through a reference center.

Biopsy specimens should be obtained when Whipple's disease is suspected even if there are no gross small bowel abnormalities, as many patients with Whipple's disease have normal appearing mucosa. In one study of 191 patient with Whipple's disease, only 26 percent had an abnormal appearing duodenum; 11 percent had findings that have been considered characteristic for Whipple's disease (ie, dilated villi, ectatic lymph vessels, prominent or discrete edema) and 10 percent had evidence of duodenitis [52].

Whipple's disease is characterized by PAS-positive macrophages on small bowel biopsy, which is usually readily apparent and unlikely to be confused with other diseases (see 'Differential diagnosis' below). The main histologic features are extensive PAS-positive material in the lamina propria [2,74] and villous atrophy (picture 1).

Results of PCR testing can also be used to make the diagnosis; the amplified DNA should be sequenced. In one series of 30 specimens from patients with histologically confirmed Whipple's disease, the sensitivity and specificity of PCR were 97 and 100 percent, respectively [75]. Lower specificity was found in another study that estimated the test to be 95 percent specific when performed on a duodenal biopsy, and 87 percent specific when performed on gastric juice [15]. False positive tests might result from the presence of T. whipplei or a closely related bacterium, which may be present in a substantial proportion of the population in the absence of Whipple's disease. Positive tests may also represent asymptomatic T. whipplei colonization.

Some laboratories perform T. whipplei PCR on blood specimens, although the clinical utility of this test has not yet been defined [81,82].

T. whipplei PCR should also be performed on the CSF whenever Whipple's disease is diagnosed, even if there are no neurological symptoms [52]. Many neurologically asymptomatic patients with Whipple’s disease have T. whipplei DNA detected on CSF PCR. As an example, in one study, 7 of 10 (70 percent) Whipple’s disease patients without neurological symptoms had a positive CSF T. whipplei PCR, compared with 4 of 5 (80 percent) with neurologic symptoms [84].

The observation that PCR of the cerebrospinal fluid is often positive in patients without neurologic symptoms suggests that late CNS symptoms probably reflect progression of initially occult infection [84].

The diagnosis of T. whipplei endocarditis is generally made by positive T. whipplei testing of a resected heart valve, usually by histology and/or immunohistochemistry. T. whipplei PCR often becomes negative soon after initiation of antibiotic therapy, which most individuals with endocarditis receive prior to valve explant.

Histologically, there are few other conditions that have a similar appearance (ie, periodic acid-Schiff positivity) on small bowel biopsy. Other infections, such as with endemic fungi (eg, Histoplasma spp), Rhodococcus, and HIV-infected mycobacterial disease, can be histologically similar to Whipple's disease, but many can be ruled in or out by additional testing (ie, staining for organisms, culture, antigen testing).

Antimicrobial resistance — In vitro susceptibility testing of T. whipplei to antibiotics in cell culture using a real-time PCR assay has demonstrated that doxycycline, macrolides, ketolides, aminoglycosides, penicillin, rifampin, teicoplanin, chloramphenicol, and trimethoprim-sulfamethoxazole (TMP-SMX) have activity, with MICs ranging from 0.25 to 2 mcg/mL [85-87]

Fluoroquinolones are not active against T. whipplei.

In addition, T. whipplei does not contain the gene that encodes dihydrofolate reductase, the target for trimethoprim activity; thus the activity of TMP-SMX is due to sulfamethoxazole alone [87].

The optimal regimen is uncertain. For patients with chronic Whipple's disease (either classic or localized chronic infection), we suggest an initial phase of an intravenous antibiotic that is active against T. whipplei and is known to penetrate the blood-brain barrier, followed by 12 months of oral maintenance therapy with trimethoprim-sulfamethoxazole (TMP-SMX) (table 1).

Evaluation of clinical response — Most adequately treated patients do well. Clinical improvement is often dramatic, occurring within 7 to 21 days [43]. However, neurological symptoms are occasionally irreversible.

There have been several reported cases of Jarisch-Herxheimer reactions one to two hours after initial therapy of Whipple's disease with intravenous antibiotics, especially penicillin. The reaction consists of fever of 39º to 40ºC, chills, headache, hypotension, and severe abdominal pain or pleuritic chest pain [22].

Those at risk for developing IRIS after starting therapy for Whipple's disease include:

● Patients who have been treated with immunosuppressive therapy for presumed rheumatic disease for an extended period prior to the diagnosis of Whipple's disease, whose immunosuppressive therapy is discontinued at the start of antibiotic treatment.

● Patients with CNS involvement of Whipple's disease.

In these circumstances, corticosteroid therapy may be beneficial; further study is needed.

Relapse — Clinical failure is suggested by a positive PCR in the relevant specimen from patients who fail to respond clinically to adequate therapy or have recurrence of symptoms after initial improvement. Clinical relapses have been reported in as many as 17 to 35 percent of patients [43,97] and, as noted above, in 7 of 12 patients who remained PCR-positive on small bowel biopsy obtained after initial therapy [75]. However, many patients with suspected relapse in these studies may have actually had IRIS.

The optimal regimen for Whipple's disease is uncertain. For patients with Whipple's disease (either classic or localized chronic infection), we suggest a regimen with an initial phase of an intravenous antibiotic that is active against T. whipplei and is known to penetrate the blood-brain barrier, such as penicillin or ceftriaxone, followed by maintenance therapy with oral trimethoprim-sulfamethoxazole (TMP-SMX) (Grade 2C)

The dose and duration of intravenous therapy and the need for adjunctive therapy depend on the clinical presentation ( table 1). TMP-SMX maintenance therapy is given for 12 months. An alternative regimen consists of doxycycline plus hydroxychloroquine with the addition of a sulfa agent for those with CNS involvement.