In 1983, the isolation of viral particles from patients with

Transcription

1 Review Articles Human Immunodeficiency Virus Related Gastrointestinal Pathology A Southern Africa Perspective With Review of the Literature (Part 1: Infections) Tomas Slavik, MBChB, FCPath(SA), MMed N Context. Human immunodeficiency virus infection is rife in sub-saharan Africa and in southern Africa in particular. Despite the increasing availability of antiretroviral therapy in this region, opportunistic infections remain common and frequently involve the gastrointestinal tract. Objective. To review the histopathologic findings and distinguishing features of human immunodeficiency virus associated gastrointestinal infections in southern Africa and relate those findings to the documented international literature. Data Sources. The available literature on this topic was reviewed and supplemented with personal experience in a private histopathology practice in South Africa. Conclusions. In southern Africa, the range of gastrointestinal, opportunistic infectious pathology in human immunodeficiency virus afflicted patients is diverse and includes viral, bacterial, fungal, and parasitic infections. This infectious pathology is sometimes a manifestation of systemic disease. In profoundly immunocompromised patients, unusual histologic features, involvement of uncommon gastrointestinal tract sites, and more than one pathogen may be seen. (Arch Pathol Lab Med. 2012;136: ; doi: / arpa ra) In 1983, the isolation of viral particles from patients with the acquired immunodeficiency syndrome (AIDS) confirmed the association between this disease and the human immunodeficiency virus (HIV). 1,2 Since then, the world has seen the unfolding of a catastrophic pandemic that rages on to this day. According to the estimated global data from the United Nations Programme on HIV/AIDS, a total of 60 million people had been infected with HIV, and 25 million people died of AIDS-related diseases by Although the pandemic appears to have stabilized significantly during the past 5 years, there were still an estimated 2.6 million new HIV infections and 1.8 million HIV-related deaths worldwide in Sub-Saharan Africa continues to bear a disproportionate amount of this burden. Most new HIV infections, an estimated 68% of the global HIV total, and 72% of global HIV-related deaths in 2009 were in this region. 4 Despite the rollout of antiretroviral therapy and recent decline in the HIV incidence and AIDS-related mortality in sub-saharan Africa, the continued spread of HIV, limited health service infrastructure, and the selective availability of antiretroviral therapy continue to contribute to these alarming figures. In the forefront of the sub-saharan HIV pandemic is southern Africa, a region comprising numerous countries at Accepted for publication July 29, From Ampath Pathology Laboratories, and the Department of Anatomical Pathology, University of Pretoria, Pretoria, South Africa. The author has no relevant financial interest in the products or companies described in this article. Reprints: Tomas Slavik, MBChB, FCPath(SA), MMed, Ampath Pathology Laboratories, Private Bag X9, Witch Hazel St, Highveld Office Park, Pretoria 0067, South Africa ( slavikt@ampath.co.za). the southernmost part of the continent. Although the United Nations scheme of geographic regions defines southern Africa as the southernmost 5 countries Botswana, Lesotho, Namibia, South Africa, and Swaziland 5 other definitions also variously include Angola, Zimbabwe, Zambia, Mozambique, and Malawi in the region. Each of the first 5 countries had an official adult HIV prevalence of more than 10% in 2008, 4 and Swaziland the highest global HIV prevalence of 26% in In absolute terms, South Africa bears the brunt of the sub-saharan pandemic, having 5.6 million HIV-infected individuals, according to 2009 estimates from the United Nations Programme on HIV/AIDS. 4 Even more sobering are data from the South African National Antenatal Sentinel HIV Prevalence Survey, which documented a 29.4% HIV prevalence among antenatal state clinic attendees countrywide in The high HIV prevalence and the relatively limited treatment options available to much of the southern African population continue to ensure the existence of a large number of immunocompromised, HIV-infected individuals who are, in turn, susceptible to a vast array of opportunistic infections (OIs). Furthermore, the profound degree of immunosuppression, the advanced stage of pathology, and the spectrum of endemic disease in this population often lead to unusual pathologic manifestations, which are now relatively uncommon in developed countries. Gastrointestinal (GI) disorders are responsible for a significant amount of HIV-related disease. 7 9 In sub-saharan Africa, diarrhea accompanied by wasting ( slim disease ) has long been documented as a prominent manifestation of HIV infection, and up to 95% of AIDS patients have been reported to suffer from diarrhea. 10 In southern Africa, GI Arch Pathol Lab Med Vol 136, March 2012 HIV-Related GI Pathology in Southern Africa (1) Slavik 305

2 OIs still remain a very common cause of diarrhea and malabsorption, 11 as was the case before the highly active antiretroviral therapy (HAART) era in developed countries. 12 Unfortunately, only limited published data are available on OIs in HIV in southern Africa, with specific literature on HIV-associated GI pathology extremely scant and largely anecdotal. In this article, the available data are reviewed, are related to international findings, and are supplemented with experience from a large, Pretoria-based, national private histopathology practice in South Africa. GI OPPORTUNISTIC INFECTIONS IN HIV Seldom appreciated as such, the GI tract represents the largest lymphoid organ in the body. 13 It is, therefore, a major site of viral replication and CD4 lymphocyte depletion during the acute phase of HIV infection, also demonstrating delayed and only partial CD4 T-cell restoration. 14 The GI tract thus plays a pivotal role in HIV infection and is affected by a variety of OIs, often as part of multisystem disease. Table 1 outlines the etiologic organisms that may be seen in HIV-associated GI infections in southern and sub-saharan Africa. Viral Infections Many viruses may cause GI disease in HIV; those associated with nonepithelial neoplasia (Human herpesvirus 8 and Epstein-Barr virus) are discussed in part 2 of this review. Cytomegalovirus (CMV) is well recognized as the mostcommon opportunistic viral pathogen in HIV, and patients with CD4 cell counts of less than 100/mL are at particular risk for GI involvement. 8,15 Almost one-half of esophageal ulcers in HIV patients in one US series before HAART was available was due to CMV. 16 In southern Africa, the Cape Town AIDS Cohort Study ( ) found herpes simplex virus (HSV) and CMV to be the most-common viral pathogens in HIV, but no reference was made to the infection sites 11 ; CMV was predominant in patients with CD4 cell counts less than 50/mL. A South African HIV pediatric endoscopic study found GI CMV infection in 27% of patients presenting with GI symptoms. 17 My practice s experience confirms the esophagus and colorectum as the most-common GI sites affected, but almost all other GI sites, including stomach, small intestine, and appendix has been seen. Multisystem disease is often, but not always, present. Additionally, one US study found up to one-third of patients with esophageal CMV infection to have another synchronous esophageal infection, usually Candida spp or, less often, HSV. 18 In the South African pediatric study, esophageal coinfection was uncommon, although GI CMV infection was accompanied by intestinal cryptosporidiosis in onequarter of patients. 17 Cytomegalovirus esophagitis typically demonstrates distal, large, and often deep ulcers. Intestinal and colorectal pathology is more variable and may include pseudomembranes, perforations, toxic megacolon, pneumatosis intestinalis, and obstructive inflammatory masses. 19 Endothelial and stromal cells are preferentially infected (Figure 1, a), but macrophages and glandular epithelium may also be involved (Figure 1, b). Characteristic of CMV are owl-eye inclusion bodies in the nucleus and frequent granular, basophilic, cytoplasmic inclusion bodies typically found in cells at the ulcer base. In patients who are severely immunocompromised, viral inclusion Table 1. Causes of Human Immunodeficiency Virus Associated Opportunistic Gastrointestinal Infections in Southern and Sub-Saharan Africa Viral Adenovirus Cytomegalovirus Herpes simplex virus Herpes varicella zoster virus Human papilloma virus Bacterial Aeromonas hydrophila Bartonella henselae/bartonella quintana Brachyspira spp (intestinal spirochetosis) Campylobacter jejuni Chlamydia trachomatis Clostridium difficile Escherichia coli (enterotoxigenic and enteroadherent) Listeria monocytogenes Mycobacterium avium complex Mycobacterium tuberculosis Neisseria gonorrhoeae Plesiomonas shigelloides Rhodococcus equi Salmonella spp Shigella flexneri Treponema pallidum Vibrio spp Yersinia spp Fungal Candida spp Cryptococcus neoformans Histoplasma capsulatum Pneumocystis jirovecii (carinii) Parasitic Cryptosporidium parvum Cyclospora cayetanensis Entamoeba histolytica Giardia lamblia (intestinalis) Isospora belli Leishmania donovani Microsporidia (Enterocytozoon bieneusi, Encephalitozoon [Septata] intestinalis) Strongyloides stercoralis Toxoplasma gondii bodies may be extremely abundant and demonstrate atypical features (Figure 1, c through f). Gastrointestinal HSV infection most often involves the esophagus but may also affect the anorectum. 20 Although much less common than CMV, international literature cites HSV as the cause of approximately 5% of esophageal ulcerative lesions. 8 In the Cape Town Aids Cohort Study, HSV was the most-common viral OI in patients with HIV who had CD4 cell counts greater than 200/mL, but the study included all body sites and was likely dominated by genital and oral HSV disease. 11 My practice s experience with HIV-associated, GI involvement attests to HSV occurring less frequently than CMV infection. Endoscopically, HSV esophagitis typically demonstrates diffuse, erosive lesions or small, discrete, superficial ulcers, without the vesicular lesions usually seen in immunocompetent hosts. 8 Herpes simplex virus characteristically infects squamous epithelium and leads to eosinophilic ground-glass inclusion bodies most often seen in syncytial cells at the ulcer margin (Figure 1, g and h). Cowdry type A eosinophilic inclusion bodies, with a surrounding halo and chromatin margination, may also be seen. 306 Arch Pathol Lab Med Vol 136, March 2012 HIV-Related GI Pathology in Southern Africa (1) Slavik

3 Human papilloma virus (HPV) is associated with anal squamous papillomas (condylomata acuminata), which are common in the context of sexually transmitted disease in southern Africa. 21 Although HIV infection increases the risk for HPV-associated anal intraepithelial neoplasia and squamous cell carcinoma, it may also predispose the patient to infection by HPV. 22,23 A significant association between HIV infection and multiple HPV coinfections was found in South African men. 21 A recent study from Zimbabwe suggested that HIV may affect genital tract immunity immediately, with a high risk of multiple, new HPV detections immediately after HIV acquisition. 24 No reliable southern Africa data are available on other, less-common HIV-associated GI viral infections, which include adenovirus and herpes varicella zoster. Adenovirus usually involves the lower GI tract, and affected epithelium demonstrates exclusively intranuclear inclusion bodies that have a basophilic smudged appearance because of an indistinct nuclear membrane. Less often, the inclusion bodies appear eosinophilic with peripheral chromatin margination. Gastrointestinal infection by herpes varicella zoster is rare but is a consideration in disseminated disease, which has been documented in southern Africa in both adults and children infected with HIV. 25,26 Herpes varicella zoster demonstrates inclusion bodies morphologically similar to HSV. Although characteristic viral inclusion bodies in GI biopsies often may be focal and require several histologic levels for identification, their detection in significantly immunocompromised HIV patients is usually not difficult. Correct histopathologic diagnosis relies on identifying the infected cell type and location and the nature of the viral inclusions and associated cellular features, as well as the judicious application of immunohistochemistry. The morphologic features of the 3 most-common HIV-associated GI OI viral inclusion bodies are contrasted in Table 2. Bacterial Infections A plethora of GI bacterial OIs has been documented in HIV, most causing an enterocolitis. The introduction of HAART has led to a dramatic decrease in these infections and a change in the etiology of this group of disorders in the developed world. 8 In some respects, the range of HIVassociated bacterial GI pathology in sub-saharan and southern Africa reflects what was seen in developed countries in the pre-haart era. Major differences exist, however, and are mainly due to the high prevalence of mycobacterial and diarrheal disease in this region. Mycobacterium spp, particularly Mycobacterium tuberculosis and Mycobacterium avium complex, are well documented as opportunistic GI pathogens in HIV. 10 Although M avium is the more-common isolate in the developed world, it occurs less frequently in the setting of HIV in sub-saharan Africa. 27,28 In southern Africa, HIV-associated mycobacterial infections are dominated by M tuberculosis. This is likely due to the large burden of tuberculosis (TB), combined with early development of antimycobacterial immunity, which is protective against the less-pathogenic M avium. 29,30 The close association between tuberculosis and HIV infection in Africa was already documented at the beginning of the HIV pandemic. 31 The emergence of multidrug-resistant and extensively drug-resistant TB in this region during the past decade has, however, deleteriously affected the already alarming morbidity and mortality of HIV-associated TB. 32 Mycobacterium tuberculosis infection of the GI tract is sometimes accompanied by active pulmonary lesions, but many patients with HIV have primary extrapulmonary TB. 33 In the Cape Town AIDS Cohort Study, 40% of patients with TB had primary extrapulmonary disease, although the site was not specified. 11 Gastrointestinal TB most often affects the ileocecum, 34 although my practice has seen tuberculosis in the setting of HIV at all levels of the GI tract. On endoscopy, ileocecal lesions are typically transverse ulcers, often with associated stricturing, but inflammatory polyps and nodules also occur. Gastric and proximal small-bowel lesions often mimic malignant ulcers. Histologic features vary from well-formed, focally necrotizing granulomas in relatively immunocompetent patients with HIV, to neutrophil-rich, histiocytic infiltrates and suppuration in the severely immunocompromised (Figure 2, a through f). Mycobacterial spindle cell pseudotumors may also occur. 35 Distinction of GI TB from Crohn disease may be difficult, particularly in immunocompetent patients with HIV, although Crohn disease is rare in indigenous African patients 36 and is uncommon in the setting of HIV. 37 The presence of abundant, large (.400 mm), confluent granulomas demonstrating fibrillogranular (caseous) necrosis, disproportionate submucosal inflammation, histiocyte palisading at the base of ulcers, and the absence of mucosal chronicity away from foci of active disease all suggest tuberculosis. 38,39 Although acidfast M tuberculosis bacilli may be extremely scant in biopsies from immunocompetent patients with HIV, they are usually readily detected in the setting of untreated HIV. Figure 2, g, demonstrates the typical histomorphology of M tuberculosis bacilli, which is contrasted with M avium in Figure 2, h. However, a large number of intracellular TB bacilli (mimicking M avium) may sometimes be seen in severely immunocompromised individuals. Infection by Yersinia spp may resemble intestinal tuberculosis histologically but is distinguished by the absence of caseous necrosis and acid-fast bacilli, and is uncommon in patients with HIV in my laboratory s experience. Some data are available for nonmycobacterial causes of HIV-related GI bacterial infections in southern Africa. A recent study on South African HIV-infected gold miners found Salmonella and Shigella species to be the mostcommon isolates, 40 although the incidence of GI disease was markedly lower than in other African studies. 41,42 An early South African pediatric study documented a high rate of diarrhea in patients with perinatally acquired HIV, the most-common isolates being Salmonella spp, Shigella spp, and Escherichia coli. 26 Nontyphoidal Salmonella spp are particularly problematic in southern and sub-saharan Africa because of their high rates of extraintestinal sepsis and mortality. 31,43 The common occurrence of schistosomiasis in the region and the known protective effect the intravascular, adult parasitic worm affords nontyphoidal Salmonella spp 44 are contributing factors, which are also significant in patients with AIDS. 45 Other diarrheagenic bacterial pathogens isolated from South African patients with HIV include Campylobacter spp, Plesiomonas shigelloides, and Aeromonas spp. 46 The histologic features of infection by these bacterial organisms are diverse and include those of acute self-limited colitis, severe acute inflammation mimicking ulcerative colitis, erosion/ulceration, and pseudomembrane formation. Arch Pathol Lab Med Vol 136, March 2012 HIV-Related GI Pathology in Southern Africa (1) Slavik 307

4 Figure 1. Gastrointestinal viral opportunistic infections in human immunodeficiency virus disease. a, Cytomegalovirus esophagitis with enlarged stromal and endothelial cells at the ulcer base, demonstrating typical owl-eye nuclear and granular, basophilic, cytoplasmic inclusion bodies. b, Cytomegalovirus gastritis revealing numerous infected cells, including glandular epithelium (arrow), with nucleocytomegaly and inclusion bodies. c, Cytomegalovirus proctitis in a severely immunocompromised patient, with large numbers of predominantly endothelial inclusion bodies in the ulcer base, many revealing a prominent signet ring appearance (arrows). d, Periodic acid Schiff (diastase sensitive) cytoplasmic staining. e, CD31 immunoperoxidase stain with globular cytoplasmic positivity in infected cells. f, Cytomegalovirus immunoperoxidase stain revealing peripherally 308 Arch Pathol Lab Med Vol 136, March 2012 HIV-Related GI Pathology in Southern Africa (1) Slavik

5 Table 2. Cell type Nucleus Cytoplasm Comparison of the 3 Most-Common Viral Inclusion Bodies Seen in Human Immunodeficiency Virus Associated Gastrointestinal Opportunistic Infections Cytomegalovirus Herpes Simplex Virus Adenovirus Endothelium, stromal, epithelium (glandular), macrophage Nucleomegaly, eosinophilic inclusion with surrounding halo/ owl-eye Cytomegaly, granular basophilic inclusion bodies Epithelium (squamous, less often glandular) Syncytial change, homogenous eosinophilic ground-glass or Cowdry type-a inclusion No inclusion Epithelium (surface columnar, goblet cell) Nucleomegaly, basophilic smudged inclusion No inclusion Although HIV-associated proctitis caused by Chlamydia trachomatis, Treponema pallidum, and Neisseria gonorrhoeae is well documented, it is relatively rare in my practice s experience. The preponderance of proctitis caused by these organisms and transmitted by homosexual men may account for its rarity 47 because this is an uncommon route for sexually transmitted disease in southern Africa. 48 Intestinal spirochetosis, initially described in HIVinfected homosexual men, is now known to occur in children and in various other disorders without associated HIV infection. 49,50 Interestingly, my practice has often seen it in the setting of HIV, which has a predominantly heterosexual route of transmission in Southern Africa. 48 In humans, intestinal spirochetosis is thought to be caused predominantly by Brachyspira aalborgi and Brachyspira pilosicoli. 51 Although the clinical significance of this disease is questioned by some authors, my practice has usually found it to be symptomatic in patients with HIV who improve on antibiotic therapy. On endoscopy, minimal or no abnormalities are seen, and histology reveals the characteristic fuzzy thin layer of entangled organisms attached to the apical surface of the colonic epithelium (Figure 3, a) with no or minimal associated inflammatory change. The organisms are readily confirmed and distinguished from enteroadherent Escherichia coli with Warthin-Starry (Figure 3, b) and periodic acid Schiff (PAS) stains. Bacillary angiomatosis, caused by Bartonella henselae and Bartonella quintana, is rare but well documented in the gut. 52,53 The lesions usually involve the upper GI tract (often with associated skin lesions) and demonstrate acute or chronic GI hemorrhage. One South African case report documented hematemesis as a presenting feature. 52 The endoscopic appearance is that of multiple friable or nodular vascular lesions, which can mimic Kaposi sarcoma. Extensive esophageal polyposis has also been described. 53 Histology reveals the typical granulation tissuelike appearance of the lesions (Figure 3, c), with scattered nuclear debris and aggregates of extracellular amphophilic granular bacterial deposits, which demonstrate a coccobacillary morphology on a Warthin-Starry stain (Figure 3, d). Clostridium difficile associated colitis has emerged as an important cause of bacterial diarrhea in patients with HIV in the post-haart era; one US study found C difficile associated colitis to be the most-common cause of HIVassociated bacterial diarrhea. 54 Although not as common in the HIV setting in southern Africa, the disease is discussed further in part 2 of this review because of its drug association. Fungal Infections International literature cites Candida spp as the mostcommon HIV-associated GI fungal pathogen. 12,55 This was also the finding in both adult and pediatric studies in southern Africa 11,17 and is borne out by my practice s experience. Regional data show oral Candida spp infection to be very common across all CD4 strata in HIV; the esophagus is the GI site most often involved, particularly in patients with CD4 cell counts less than 200/mL. 11 Esophageal infection may occur in the absence of oral thrush, and endoscopy usually demonstrates characteristic white plaques and erosions; frank ulceration, pseudomembranes, and even infarction may be seen in other parts of the GI tract. Depending on the patient s immune status, histology reveals a variable acute inflammatory response and variable numbers of Candida spp organisms, present as budding yeasts and pseudohyphae (Figure 3, e and f). Human immunodeficiency virus associated GI infection caused by Cryptococcus neoformans is uncommon in developed countries and is usually part of systemic disease. 56 Cryptococcosis has been documented at all levels of the GI tract, with the upper tract most often involved. 57,58 In southern Africa, C neoformans is a common fungal pathogen and an important cause of HIV-associated mortality, seen predominantly in patients with CD4 cell counts less than 50/mL. 11,40,59 Although it rarely affects the GI tract in my practice, it usually does so in disseminated disease and is associated with a high mortality. Endoscopy may reveal nodular lesions, ulceration, and deep mural involvement. Histology confirms the characteristic encapsulated, narrow-neck budding, pleomorphic fungal yeasts with a surrounding inflammatory response. This may have granulomatous features, but in cases of advanced HIV, the response most often varies from suppurative and necrotizing to completely absent. The fungal yeasts are positive on PAS (diastase resistant) and silver stains, whereas the capsule of variable thickness demonstrates positivity using mucicarmine, Alcian blue, colloidal iron, and Fontana- Masson stains. r displaced and compressed infected nuclei. g, Herpes simplex virus (HSV) esophagitis, with characteristic syncytial squamous epithelial cells at the ulcer edge, eosinophilic ground-glass nuclear inclusion bodies, and peripheral chromatin margination. h, Numerous, similar HSV inclusion bodies in both mononucleated and multinucleated squames (hematoxylin-eosin, original magnifications 3400 [a through c, g, and h]; original magnifications 3400 [d through f]). Arch Pathol Lab Med Vol 136, March 2012 HIV-Related GI Pathology in Southern Africa (1) Slavik 309

6 Figure 2. Gastrointestinal tuberculosis in human immunodeficiency virus infection. a, Ulcerative esophagitis with isolated, moderately formed lamina propria granulomas (at right). b, Edge of an endoscopically malignant-appearing duodenal ulcer revealing granulomatous infiltrate at bottom left. c, Cecal polyp demonstrating predominantly submucosal granulomas. d, Characteristic fibrillogranular (caseous) necrosis containing abundant nuclear debris, surrounded by numerous epithelioid cell granulomas. e, Tuberculous appendix abscess in a profoundly immunocompromised adult (who also had Candida esophagitis and cryptosporidiosis) demonstrating Crohn-like fissure (arrow) and adjacent mucosal crypt architectural distortion. f, Underlying mural microabscesses and scattered histiocytes. g, Mycobacterium tuberculosis on a Ziehl-Neelsen (ZN) stain, revealing 310 Arch Pathol Lab Med Vol 136, March 2012 HIV-Related GI Pathology in Southern Africa (1) Slavik

7 Pneumocystis jirovecii (formerly Pneumocystis carinii) GI infection almost always occurs as part of disseminated disease in severely immunocompromised patients, with aerosolized pentamidine prophylaxis being a major risk factor for GI involvement. 60,61 Data on HIV-associated P jirovecii infection in southern Africa seem to indicate that it may not be as common as in other parts of the continent or in the developed countries before the HAART era. 11,25,26,40 Involvement of the GI tract at any level may occur, but the esophagus, stomach, and colon are most often affected Endoscopic findings are nonspecific and erosive, ulcerative, nodular or polypoid lesions may be seen. The histologic response varies and may be weakly granulomatous to histiocytic, often demonstrating plasma cells. Organisms can be identified in the characteristic foamy and necrotic exudate using silver-based and PAS stains. Parasitic Infections Gastrointestinal parasitic infections are common in cases of HIV in southern and sub-saharan Africa, largely because of their high prevalence in subtropical regions and because of prevailing poor socioeconomic conditions Coccidian infections predominate in the setting of HIV. Many reports from before HAART therapy was developed found Cryptosporidium parvum to be the mostcommon cause of diarrhea in patients with AIDS The scant data available on patients from southern Africa seem to confirm this, with one pediatric study reporting cryptosporidiosis as the most-common HIV-associated GI parasitic OI. 17 My practice s recent series of upper, doublelumen, and lower endoscopic GI biopsies on treatmentnaïve patients with advanced HIV (CD4, 200 cells/ml) who presented with diarrhea identified Cryptosporidium spp to be the most-common GI OI in 9 of 34 patients (26%; unpublished data). Although cryptosporidiosis most often affects the proximal small bowel, concomitant involvement of the colorectum is frequently seen. Gastric, pancreaticobiliary, and disseminated disease usually occurs in severely immunocompromised patients and has a dismal outcome. 69 Typically, no endoscopic abnormalities are present. Small-bowel histology demonstrates villous atrophy, crypt hyperplasia, epithelial disarray, and prominent, mixed inflammatory cell infiltration with numerous eosinophils. Similar inflammatory changes occur at other involved GI sites. Organisms are readily identified as 2- to 5-mm basophilic spheres protruding from below the apical membrane of epithelial cells and stain positively with Warthin-Starry, Giemsa, and Gram stains (Figure 4, a and b). Entamoeba histolytica, a common pathogenic amoeba with a worldwide distribution, is endemic to parts of southern Africa. 70 It usually infects healthy individuals but has a documented association with HIV, particularly in homosexual men A recent South African study reported a significantly higher E histolytica seroprevalence among rural patients with HIV, with the highest risk in patients with CD4 cell counts less than 200 cells/ml. 74 Although E histolytica typically affects the right colon, involvement of other parts of the large or small bowel and dissemination with peritonitis and abscess formation (usually in the liver and lung) may occur in HIV cases. My practice has seen isolated cases of HIV-associated amoebic colitis complicated by bowel perforation, amoebic peritonitis, and patient demise. The bowel segment affected by amebiasis characteristically demonstrates necrotizing acute inflammation and undermining flaskshaped ulcers, but rarely, tumoral masses (so-called amebomas) may occur. Numerous parasites (often mimicking histiocytes) are usually present in the necroinflammatory debris and demonstrate erythrophagocytosis, distinguishing this organism from nonpathogenic E dispar (Figure 4, c and d). Erythrophagocytosis, as well as the pale washed-out appearance of the parasite nucleus and strong PAS (diastase sensitive) cytoplasmic positivity allows distinction from histiocytes (Figure 4, e). Microsporidial GI infections in HIV are most often caused by Enterocytozoon bieneusi and Encephalitozoon (Septata) intestinalis. In southern Africa, many cases were reported 75 in Zimbabwe as early as 1995, the first South African case was documented 76 in 1998, and there were isolated subsequent cases reported 77 in The parasites most often infect the small bowel and are an important cause of persistent diarrhea in HIV. 78 No official data exist for southern Africa HIV-associated microsporidiosis. The parasites are, however, easily missed on stool microscopy as well as routine hematoxylin-eosin stained biopsy sections (because of their intracellular location, small size, and granular appearance) and are undoubtedly underdiagnosed in this region. A high index of suspicion is required for histologic identification and modified trichrome as well as Brown-Brenn/Gram or Warthin-Starry stains are recommended to prevent false-negative diagnoses on biopsy. 79 Examination under polarized light may highlight the organism s polar filament, but this is a notoriously insensitive histologic detection technique. Giardia lamblia is a flagellate that usually infects otherwise healthy individuals and often occurs in children. It has, however, been reported in association with AIDS, particularly in homosexual men. 80 Although no data are available to confirm or refute that association in southern Africa, my practice has seen cases of giardiasis in patients with HIV. The high prevalence of giardiasis in southern Africa and the predominantly heterosexual spread of HIV in the region, however, make these cases likely to represent incidental coinfections. Isospora belli is another, less-common coccidian that most often involves the small bowel, although colorectal and disseminated disease have been documented. 81 Endoscopic and histologic features are similar to cryptosporidiosis, although lamina propria fibrosis may be seen in chronic cases. Organisms are large (15 20 mm), usually located in a perinuclear or subnuclear, intraepithelial location, and stain positively with Giemsa, PAS, and methenamine silver stains. Asexual forms are usually crescentic to ovoid ( banana-shaped ), whereas sexual forms are round to oval and demonstrate a prominent nucleus (Figure 4, f and g). r scattered, long, slender, and serpentine bacilli, many of which are extracellular and appear slightly out of the plane of focus. h, Mycobacterium avium complex on a ZN stain; macrophages demonstrate extremely large numbers of shorter, thicker intracellular bacilli, which are positive on periodic acid- Schiff staining (hematoxylin-eosin, original magnifications 3200 [a through c], 3400 [d and f], and 340 [e]; original magnifications 3400 [g and h]). Arch Pathol Lab Med Vol 136, March 2012 HIV-Related GI Pathology in Southern Africa (1) Slavik 311

8 Figure 3. Gastrointestinal (GI) bacterial and fungal infections in human immunodeficiency virus disease. a, Intestinal spirochetosis colonic mucosa demonstrating a fuzzy luminal border comprising a thin layer of adherent spirochetes. b, Warthin-Starry (WS) stain highlighting the organism layer. c, Bacillary angiomatosis, a rare finding in the GI tract, demonstrating granulation tissuelike appearance with plump endothelium. d, The WS stain reveals numerous aggregates of Bartonella spp coccobacilli (arrow) in the lesion. e, Candida esophagitis acute inflammation with very scant fungal organisms on Alcian blue/periodic acid Schiff (AB/PAS) stain. f, An esophageal plaque with many yeasts and pseudohyphae, interspersed squames, bacterial aggregates, and extremely sparse inflammatory cell infiltrate on AB/PAS (hematoxylin-eosin, original magnifications 3400 [a and c]; original magnifications 3400 [b and d through f]). Toxoplasma gondii may rarely involve the GI tract in HIV, where it is seen as part of disseminated disease.82,83 The stomach or, less often, the colon is involved, and endoscopy may reveal no abnormality, ulceration, or 312 Arch Pathol Lab Med Vol 136, March 2012 diffuse mucosal/mural thickening.84 Histologic features vary from nonspecific inflammation to necrosis, and pseudocysts with tachyzoites, as well as cysts with bradyzoites, may be seen (Figure 4, h). Careful histomorphologic HIV-Related GI Pathology in Southern Africa (1) Slavik

9 Figure 4. Gastrointestinal parasites in human immunodeficiency virus infection. a, Gastric cryptosporidiosis in a patient with esophageal Cytomegalovirus infection, demonstrating prominent, acute inflammation and abundant basophilic, spherical organisms at the luminal surface of the gastric epithelium, highlighted in (b) by a Warthin-Starry stain. c, Entamoeba histolytica infection of the ileocecal region showing inflamed colonic mucosa with adjacent aggregates of parasites, demonstrating a pale nucleus, erythrophagocytosis (arrow) (d) and an intense cytoplasmic periodic acid Schiff (diastase-sensitive) positivity (e). f, Isospora belli duodenitis with focal surface epithelial disarray, inflammatory changes, and numerous intraepithelial parasites (arrows). g, Both sexual (arrowhead, macrogametocyte) and asexual (arrow) forms are present. h, Gastric toxoplasmosis numerous glandular cysts packed with bradyzoites (hematoxylin-eosin, original magnifications 3400 [a, f, and h], 3200 [c], and [d and g]; original magnifications [b and e]). Arch Pathol Lab Med Vol 136, March 2012 HIV-Related GI Pathology in Southern Africa (1) Slavik 313

10 examination, supplemented with PAS and Giemsa stains and immunohistochemistry, confirm the tissue diagnosis. Polymerase chain reaction is also of value in distinguishing this organism from Histoplasma and Leishmania species, particularly in severely immunocompromised patients who may have negative results with Toxoplasma spp serology. 85 Cyclospora cayetanensis, the most recently identified coccidian, presents with similar pathologic features to Cryptosporidium and Isospora species. 86,87 Organisms in histologic sections are documented to be of similar size or slightly larger than Cryptosporium spp and are usually located in a parasitophorous vacuole in the upper part of the epithelial cell. They are acid-fast and auramine positive, but negative for PAS, Giemsa, Gram, and silver stains. This parasite has been reported in South Africa, 88 but no data are available for HIV-related GI infection by C cayetanensis in the region. No biopsied cases on record exist from my practice s laboratory. Strongyloides stercoralis is a nematode more commonly seen in central and northern Africa, where an association with HIV has been documented. 89 In southern Africa, a recent article reported this parasite in the HIV setting with hyperinfection leading to mesenteric lymphadenopathy and intestinal pseudo-obstruction. 90 CONCLUSION In 2009, an estimated two-thirds of the global HIV burden and three-quarters of the world s AIDS-related deaths were in sub-saharan Africa, with the highest HIV prevalence rates seen in southern Africa. Despite encouraging indications of a containment of HIV spread in this region, there remains a large population of patients in southern Africa who are HIV-infected and immunocompromised and who are susceptible to a vast array of OIs. These OIs frequently involve the GI tract and are often part of systemic disease. Although much of the HIVrelated infectious GI pathology in southern Africa mirrors that seen in the pre-haart era in the developed world, numerous infections endemic to this region are responsible for pathologic manifestations seldom seen in developed countries. Furthermore, the profound immunosuppression often seen in HIV patients in this region may lead to unusual histologic features, involvement of uncommon GI sites, and infection by more than one opportunistic pathogen. The cornerstone of correct histopathologic diagnosis of HIV-associated GI OIs in the resource-limited setting of southern Africa remains careful morphologic evaluation of routine hematoxylin-eosin stained sections, combined with a high index of suspicion. This should be supplemented with a thorough knowledge of the patient s clinical presentation, judicious use of ancillary stains, and close correlation with microbiologic studies. The author wishes to thank Mr Eric Liebenberg, Division of Anatomical Pathology, Faculty of Health Sciences, University of Witwatersrand, Johannesburg, South Africa, for technical assistance with microphotographic material. The case in Figure 4, h, is provided courtesy of M. Shaw, MMed, Windhoek, Namibia. References 1. Barré-Sinoussi F, Chermann JC, Rey F, et al. Isolation of a T-lymphotropic retrovirus from a patient at risk for acquired immune deficiency syndrome (AIDS). Science. 1983;220(4599): Gallo RC, Sarin PS, Gelmann EP, et al. Isolation of human T-cell leukemia virus in acquired immune deficiency syndrome (AIDS). Science. 1983;220(4599): United Nations Programme on HIV/AIDS. UNAIDS global facts and figures / _fs_global_en.pdf. Updated September Accessed April 23, United Nations Programme on HIV/AIDS. Epidemic update: global report. Geneva, Switzerland: UNAIDS. GlobalReport_Chap2_em.pdf. Updated Accessed April 23, United Nations Statistics Division. Composition of macro geographical (continental) regions, geographical sub-regions, and selected economic and other groupings. Accessed May 17, South African Department of Health 2010, National antenatal sentinel HIV and syphilis seroprevalence survey in South Africa org.za/documents/85d3dad613e8ca9d02cceb7f4a36145.pdf. Accessed May 17, Mocroft A, Brettle R, Kirk O, et al. Changes in the cause of death among HIV positive subjects across Europe: results from the EuroSIDA study. AIDS. 2002;16(12): Wallace MR, Brann OS. Gastrointestinal manifestations of HIV infection. Curr Gastroenterol Rep. 2000;2(4): Ho-Yen C, Chang F, van der Walt J, Lucas S. Gastrointestinal malignancies in HIV-infected or immunosuppressed patients: pathologic features and review of the literature. Adv Anat Pathol. 2007;14(6): Mayer HB, Wanke CA. Diagnostic strategies in HIV-infected patients with diarrhea. AIDS. 1994;8(12): Holmes CB, Wood R, Badri M, et al. CD4 decline and incidence of opportunistic infections in Cape Town, South Africa: implications for prophylaxis and treatment. J Acquir Immune Defic Syndr. 2006;42(4): Knox TA, Spiegelman D, Skinner SC, Gorbach S. Diarrhea and abnormalities of gastrointestinal function in a cohort of men and women with HIV infection. Am J Gastroenterol. 2000;95(12): Antony SJ. HIV enteropathy a challenge in diagnosis and management. J Natl Med Assoc. 1994;86(5): Brenchley JM, Douek DC. HIV infection and the gastrointestinal immune system. Mucosal Immunol. 2008;1(1): Kaplan JE, Benson C, Holmes KH, et al. Guidelines for prevention and treatment of opportunistic infections in HIV-infected adults and adolescents: recommendations from CDC, the National Institutes of Health, and the HIV Medicine Association of the Infectious Diseases Society of America. MMWR Recomm Rep. 2009;58(RR-4): Wilcox CM, Schwartz DA, Clark WS. Esophageal ulceration in human immunodeficiency virus infection: causes, response to therapy and long term outcome. Ann Intern Med. 1995;123(2): Cooke ML, Goddard EA, Brown RA. Endoscopy findings in HIV-infected children from sub-saharan Africa. J Trop Pediatr. 2009;55(4): Bonacini M, Young T, Laine L. The causes of esophageal symptoms in human immunodeficiency virus infection. Arch Intern Med. 1991;151(8): Chetty R, Roskell DE. Cytomegalovirus infection in the gastrointestinal tract. J Clin Pathol. 1994;47(11): Brar HS, Gottesman L, Surawicz C. Anorectal pathology in AIDS. Gastrointest Endosc Clin North Am. 1998;8(4): Müller EE, Chirwa TF, Lewis DA. Human papillomavirus (HPV) infection in heterosexual South African men attending sexual health services: associations between HPV and HIV serostatus. Sex Transm Infect. 2010;86(3): Clark MA, Hartley A, Geh JI. Cancer of the anal canal. Lancet Oncol. 2004;5(3): Palefsky JM, Holly EA, Hogeboom CJ, et al. Virologic, immunologic and clinical parameters in the incidence and progression of anal squamous intraepithelial lesions in HIV-positive and HIV-negative homosexual men. J Acquir Immune Defic Syndr Hum Retrovirol. 1998;17(4): Nowak RG, Gravitt PE, Morrison CS, et al. Increases in human papillomavirus detection during early HIV infection among women in Zimbabwe. J Infect Dis. 2011;203(8): Karstaedt AS. AIDS the Baragwanath experience, part III: HIV infection in adults at Baragwanath hospital. S Afr Med J. 1992;82(2): Friedland IR, McIntyre JA. AIDS the Baragwanath experience, part II: HIV infection in pregnancy and childhood. S Afr Med J. 1992;82(2): Gilks CF, Brindle RJ, Mwachari C, et al. Disseminated mycobacterium infection among HIV-infected patients in Kenya. J Acquir Immune Defic Syndr. 1995;8(2): Okello DO, Sewankambo N, Goodgame R, et al. Absence of bacteremia with Mycobacterium avium-intracellulare in Ugandan patients with AIDS. J Infect Dis. 1990;162(1): Schaaf HS, Moll AP, Dheda K. Multidrug-and extensively drug-resistant tuberculosis in Africa and South America: epidemiology, diagnosis and management in adults and children. Clin Chest Med. 2009;373(9678): Horsburgh CR, Hanson DL, Jones JL, Thomson SE. Protection from Mycobacterium avium complex disease in HIV-infected persons with a history of tuberculosis. J Infect Dis. 1996;174(6): Lucas SB, Odida M, Wabinga H. The pathology of severe morbidity and mortality caused by HIV infection in Africa. AIDS. 1991;5(suppl 1):S143 S Arch Pathol Lab Med Vol 136, March 2012 HIV-Related GI Pathology in Southern Africa (1) Slavik

11 32. Dheda K, Warren RM, Zumla A, Grobusch MP. Extensively drug-resistant tuberculosis: epidemiology and management challenges. Infect Dis Clin North Am. 2010;24(3): Horvath KD, Whelan RL. Intestinal tuberculosis: return of an old disease. Am J Gastroenterol. 1998;93(5): Marshall JB. Tuberculosis of the gastrointestinal tract and peritoneum. Am J Gastroenterol. 1993;88(7): Basilio-de-Oliveira C, Eyer-Silva WA, Valle HA, Rodrigues AL, Pinheiro Pimentel AL, Morais-De-Sá CA. Mycobacterial spindle cell pseudotumor of the appendix vermiformis in a patient with AIDS. Braz J Infect Dis. 2001;5(2): Wright JP, Froggatt J, O Keefe EA, et al. The epidemiology of inflammatory bowel disease in Cape Town S Afr Med J. 1986;70(1): Epstein D, Watermeyer G, Kirsch R. Review article: the diagnosis and management of Crohn s disease in populations with high-risk rates for tuberculosis. Aliment Pharmacol Ther. 2007;5(12): Pulimood AB, Peter S, Ramakrishna BS, et al. Segmental colonoscopic biopsies in the differentiation of ileocolonic tuberculosis from Crohn s disease. J Gastroenterol Hepatol. 2005;20(5): Pulimood AB, Ramakrishna BS, Kurian G, et al. Endoscopic mucosal biopsies are useful in distinguishing granulomatous colitis due to Crohn s disease from tuberculosis. Gut. 1999;45(4): Corbett EL, Churchyard GJ, Charalambos S, et al. Morbidity and mortality in South African gold miners: impact of untreated disease due to human immunodeficiency virus. Clin Infect Dis. 2002;34(9): Clerinx J, Bogaerts J, Taelman H, et al. Chronic diarrhea among adults in Kigali, Rwanda: association with bacterial enteropathogens, rectocolonic inflammation, and human immunodeficiency virus infection. Clin Infect Dis. 1995;21(5): Grant AD, Djomand G, Smets P, et al. Profound immunosuppression across the spectrum of opportunistic disease among hospitalized HIV-infected adults in Abidjan, Côte d Ivoire. AIDS. 1997;11(11): Gordon MA, Banda HT, Gondwe M, et al. Non-typhoidal salmonella bacteraemia among HIV-infected Malawian adults: high mortality and frequent recrudescence. AIDS. 2002;16(12): Melhem RF, LoVerde PT. Mechanism of interaction of Salmonella and Schistosoma species. Infect Immun. 1984;44(2): Lambertucci JR, Rayes AA, Gerspacher-Lara R. Salmonella-S. mansoni association in patients with acquired immunodeficiency syndrome. Rev Inst Med Trop Sao Paulo. 1998;40(4): Obi CL, Bessong PO. Diarrhoeagenic bacterial pathogens in HIV-positive patients with diarrhoea in rural communities of Limpopo Province, South Africa. J Health Popul Nutr. 2002;20(3): Rompalo AM. Diagnosis and treatment of sexually acquired proctitis and proctocolitis: an update. Clin Infect Dis. 1999;28(suppl 1):S84 S United Nations Programme on HIV/AIDS. East and southern Africa. Accessed May 14, Surawicz CM. Intestinal spirochetosis in homosexual men. Am J Med. 1988;82(3): Koteish A, Kannangai R, Abraham SC, Torbenson M. Colonic spirochetosis in children and adults. Am J Clin Pathol. 2003;120(6): Tsinganou E, Gebbers J-O. Human intestinal spirochetosis a review. Ger Med Sci. 2010;8:Doc01. doi: / Chetty R, Sabaratnam RM. Upper gastrointestinal bacillary angiomatosis causing hematemesis: a case report. Int J Surg Pathol. 2003;11(3): Chang AD, Drachenberg CI, James SP. Bacillary angiomatosis associated with extensive esophageal polyposis: a new mucocutaneous manifestation of acquired immunodeficiency disease (AIDS). Am J Gastroenterol. 1996;91(10): Sanchez TH, Brooks JT, Sullivan PS, et al. Bacterial diarrhea in persons with HIV infection, United States, Clin Infect Dis. 2005;41(11): Huppmann AR, Orenstein JM. Opportunistic disorders of the gastrointestinal tract in the age of highly active antiretroviral therapy. Hum Pathol. 2010; 41(12): Washington K, Gottfried MR, Wilson ML. Gastrointestinal cryptococcosis. Mod Pathol. 1991;4(6): Le NM, Alave J, Martinez D, Bustamante B, Rodriguez M, Seas C. Symptomatic duodenal cryptococcosis in HIV-infected individuals [published online ahead of print February 28, 2011]. Med Mycol. doi: / Girardin M, Greloz V, Hadengue A. Cryptococcal gastroduodenitis: a rare location of the disease. Clin Gastroenterol Hepatol. 2010;8(3):e28 e Moosa MY, Coovadia YM. Cryptococcal meningitis in Durban, South Africa: a comparison of clinical features, laboratory findings and outcome for human immunodeficiency virus (HIV)-positive and HIV-negative patients. Clin Infect Dis. 1997;24(2): Dieterich DT, Lew EA, Bacon DJ, Pearlman KI, Scholes JV. Gastrointestinal pneumocystosis in HIV-infected patients on aerosolized pentamidine: report of five cases and literature review. Am J Gastroenterol. 1992;87(12): DeRoux SJ, Adsay NV, Ioachim HL. Disseminated pneumocystosis without pulmonary involvement during prophylactic aerosolized pentamidine therapy in a patient with the acquired immunodeficiency syndrome. Arch Pathol Lab Med. 1991;115(11): Kinchen K, Kinchen TH, Inglesby T Jr. Pneumocystis carinii infection of the small intestine. J Natl Med Assoc. 1998;90(10): Yoshida EM, Filipenko D, Phillips P, Montaner JS, Whittaker JS. AIDSrelated extrapulmonary Pneumocystis carinii infection presenting as a solitary rectal ulcer. Can J Gastroenterol. 1996;10(6): Samie A, Guerrant RL, Barrett L, Bessong PO, Igumbor EO, Obi CL. Prevalence of intestinal parasitic and bacterial pathogens in diarrhoeal and non-diarrhoeal human stools from Vhembe district, South Africa. J Health Popul Nutr. 2009;27(6): Lewthwaite P, Gill GV, Hart CA, Beeching NJ. Gastrointestinal parasites in the immunocompromised. Curr Opin Infect Dis. 2005;18(5): Conlon CP, Pinching AJ, Perera CU, Moody A, Luo NP, Lucas SB. HIVrelated enteropathy in Zambia: a clinical, microbiological and histological study. Am J Trop Med Hyg. 1990;42(1): Lopez AP, Gorbach SL. Diarrhea in AIDS. Infect Dis Clin North Am. 1988; 2(3): Rolston KV, Rodriguez S, Hernandez M, Bodey GP. Diarrhea in patients infected with the human immunodeficiency virus. Am J Med. 1989;86(1): Manabe YC, Clark DP, Moore RD, et al. Cryptosporidiosis in patients with AIDS: correlates of disease and survival. Clin Infect Dis. 1998;27(3): Stauffer W, Abd-Alla M, Ravdin JI. Prevalence and incidence of Entamoeba histolytica infection in South Africa and Egypt. Arch Med Res. 2006;37(2): Hung CC, Wu PY, Chang SY, et al. Amebiasis among persons who sought voluntary counseling and testing for human immunodeficiency virus infection: a case-control study. Am J Trop Med Hyg. 2011;84(1): James R, Barratt J, Marriott D, Harkness J, Stark D. Seroprevalence of Entamoeba histolytica infection among men who have sex with men in Sydney, Australia. Am J Trop Med Hyg. 2010;83(4): Chen Y, Zhang Y, Yang B, et al. Seroprevalence of Entamoeba histolytica infection in HIV-infected patients in China. Am J Trop Med Hyg. 2007;77(5): Samie A, Barrett LJ, Bessong PO, et al. Seroprevalence of Entamoeba histolytica in the context of HIV and AIDS: the case of Vhembe district, in South Africa s Limpopo province. Ann Trop Med Parasitol. 2010;104(1): Van Gool T, Luderhoff E, Nathoo KJ, Klire CF, Dankert J, Mason PR. High prevalence of Enterocytozoon bieneusi infections among HIV-positive individuals with persistent diarrhea in Harare, Zimbabwe. Trans R Soc Trop Med Hyg. 1995;89(5): Dini L, Frean J, Pendle S, Sacks L. First report of microsporidiosis in South Africa. S Afr Med J. 1998;88(1): Von Gottberg AM, Dini LA, Frean JA. Confirmation of transmission of the microsporidian parasite Enterocytozoon bieneusi in South Africa. S Afr Med J. 2000;90(3): Curry A, Canning EU. Human microsporidiosis. JInfect. 1993;27(3): Lamps LW, Bronner MP, Vnencak-Jones CL, Tham KT, Mertz HR, Scott MA. Optimal screening and diagnosis of microsporidia in tissue sections: a comparison of polarization, special stains and molecular techniques. Am J Clin Pathol. 1998;109(4): Esfandiari A, Swartz J, Teklehaimanot S. Clustering of giardiasis among AIDS patients in Los Angeles County. Cell Mol Biol. 1997;43(7): Lindsay DS, Dubey JP, Blagburn BL. Biology of Isospora spp from humans, nonhuman primates, and domestic animals. Clin Microbiol Rev. 1997;10(1): Smart PE, Weinfeld A, Thompson ME, Defortuna SM. Toxoplasmosis of the stomach: a cause of antral narrowing. Radiology. 1990;174(2): Peraire J, Vidal F, Mayayo E, Razquin S, Richart C. Gastric toxoplasmosis in the acquired immunodeficiency syndrome. Am J Gastroenterol. 1993;88(9): Alpert L, Miller M, Alpert E, Satin R, Lamoureux E, Trudel L. Gastric toxoplasmosis in acquired immunodeficiency syndrome: antemortem diagnosis with histopathologic characterization. Gastroenterology.1996;110(1): Bertoli F, Espino M, Arosemena JR, Fishback JL, Frenkel JK. A spectrum in the pathology of toxoplasmosis in patients with acquired immunodeficiency syndrome. Arch Pathol Lab Med. 1995;119(3): Ortega YR, Sterling CR, Gilman RH, Cama VA, Diaz F. Cyclospora species a new protozoan pathogen of humans. N Engl J Med. 1993;328(18): Connor BA, Reidy J, Soave R. Cyclosporiasis: clinical and histopathologic correlates. Clin Infect Dis. 1999;28(6): Markus MB, Frean JA. Occurrence of human Cyclospora infection in sub- Saharan Africa. S Afr Med J. 1993;83(11): Assefa S, Erko B, Medhin G, Assefa Z, Shimelis T. Intestinal parasitic infections in relation to HIV/AIDS status, diarrhea and CD4 T-cell count. BMC Infect Dis. 2009;18(9): Ramdial PK, Hlatshwayo NH, Singh B. Strongyloides stercoralis mesenteric lymphadenopathy: clue to the etiopathogenesis of intestinal pseudoobstruction in HIV-infected patients. Ann Diagn Pathol. 2006;10(4): Arch Pathol Lab Med Vol 136, March 2012 HIV-Related GI Pathology in Southern Africa (1) Slavik 315