and Pallav Gupta2
(1)
Department of Pathology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India
(2)
Department of Histopathology, Sir Ganga Ram Hospital, New Delhi, India
Immunocompromised patients present with altered pattern, progression, and clinical manifestations of parasitic infections. Patients with impaired cell-mediated immunity are susceptible to infection with Toxoplasma gondii, Cryptosporidium, Leishmania, Strongyloides, and Microspora. Defects in humoral immunity make the patient susceptible to infection by parasites like Giardia lamblia and Cryptosporidium. The immunocompromised patients are at risk of developing the following parasitic infections.
Table 5.1
Common opportunistic parasitic infections
Intestinal protozoa | Tissue protozoa | Hemoflagellates | Intestinal nematodes |
|---|---|---|---|
Giardia lamblia | Toxoplasma gondii | Leishmania | Strongyloides stercoralis |
Entamoeba | |||
Cryptosporidium parvum | |||
Cyclospora | |||
Isospora belli | |||
Sarcocystis | |||
Microsporidia |
Giardia lamblia:
G. lamblia is a flagellated intestinal protozoon. Immunocompromised individuals are more susceptible to the development of chronic giardiasis. The organism is transmitted via fecal-oral route. Clinical manifestations are variable. Both cyst and trophozoite forms may be demonstrated in stool samples. Trophozoites of Giardia may be seen as pear-shaped, sickle, or crescent-shaped structures adhering to crypts of mucosal epithelium of the duodenum and proximal jejunum.
Giardiasis Duodenum in a Patient of Short Bowel Syndrome
Fig. 5.1
(a, b) A 31-year-old male patient who underwent surgery for acute abdomen later presented with large volume watery diarrhea, extreme emaciation, and weight loss. On investigations he was found to have short bowel syndrome with the absence of a large length of the ileum. Duodenal biopsy revealed Giardia in the duodenal crypts suggesting giardiasis of the duodenum (a HE ×400 and b Giemsa ×400) (From: R K Gupta. Pathology of Opportunistic Infections in Tropics. Jaypee; 2007)
Entamoeba:
Entamoeba histolytica is an intestinal protozoan parasite. Invasive amoebiasis is common in immunocompromised host. Primary amoebic encephalitis is caused by free-living amoeba, e.g., Naegleria, Acanthamoeba, and rarely Balamuthia mandrillaris. These amoebae are specifically neurotropic.
Acanthamoeba Brain
Fig. 5.2
(a, b) A 36-year-old agricultural worker was brought to the hospital with the history of fever, headache, vomiting, and cough with expectoration for 10 days. He had acidotic breathing and was drowsy. Clinical examination revealed right hemiparesis. Fundoscopy revealed bilateral papilledema. CSF examination revealed raised proteins and lymphocytic pleocytosis with occasional histiocytes. He had three episodes of seizures on the sixth day of admission followed by cardiopulmonary arrest to which he succumbed. At postmortem the gross examination of the brain showed areas of hemorrhagic infarct in the frontal lobe. Histological examination revealed necrotic tissue with the presence of a few large trophozoites and cyst of Acanthomoeba (a HE ×400 and b PAS ×1000) (Contributors: Dr. Anita Mahadevan and Prof. S K Shankar, Human Brain Bank, Department of Neuropathology, NIMHANS, Bangalore) (From: R K Gupta. Pathology of opportunistic infections in tropics. Jaypee; 2007)
Balantidium coli:
It is a ciliated protozoan causing zoonotic infection. Pig is an important natural reservoir. The infection is transmitted to man through food and water contaminated by fecal matter of pig. Infection in man could both be intestinal and extraintestinal. It is the largest protozoa; the trophozoites have granular cytoplasm with two nuclei, one bean-shaped macronucleus, and a small micronucleus.
Balantidium coli in a Cavitary Lung Lesion in an Immunocompromised Patient
Fig. 5.3
A 23-year-old male Indian national studying medicine in Russia presented with swelling all over the body for 4 months along with nausea, vomiting, and hiccups for 2 days. Serum creatinine was 8.9 mg/dl and blood urea 178 mg/dl; urine examination revealed active sediment. He was on steroids for 10 months and was HIV negative. X-ray chest revealed a cavitary lesion in the basal segment of the left lung. Guided FNAC of the lung revealed large round- to oval-ciliated structures with an eccentrically placed reniform nucleus, the background showed necrotic debris (HE ×400). Wet preparation showed that these organisms were actively motile with cilia suggestive of trophozoites of Balantidium coli. Stains for AFB and fungus were negative. Renal biopsy showed amyloidosis (Contributors: Dr. S. Radha and Dr. Tameem Afroz, Department of Pathology, Aware Global Hospital, Hyderabad, India) (From: R K Gupta. Pathology of Opportunistic Infections in Tropics. Jaypee; 2007)
Cryptosporidium:
Cryptosporium parvum is an intestinal protozoan. It is one of the common opportunistic infections in patients of AIDS. Immunocompromised patients present with severe prolonged diarrhea with fatal outcome. The infection is transmitted from animals or person to person contact through fecal-oral route. The Cryptosporidium infects the mucosa of the gastrointestinal tract with the jejunum being the most heavily infected site. The sporozoites attach to the apical membrane of enterocytes. Duodenal/jejunal mucosal biopsy shows small rounded organisms (1–3 μm).
Cryptosporidiosis Duodenum in a HIV-Positive Patient
Fig. 5.4
(a, b) A 56-year-old female patient with history of blood transfusion from a professional donor for an ovarian surgery 8 years back presented with increased frequency of stools, large volume watery diarrhea, occasional vomiting, loss of weight, and fever. Upper GI endoscopy revealed nodularity in the upper esophagus and stomach. Duodenal biopsy showed partial villous atrophy with the presence of small rounded organisms of Cryptosporidium closely apposed to the surface epithelium (a HE ×400, b HE ×1000). Gastric biopsy also showed Cytomegalovirus infection. The patient was HIV positive with absolute CD4 count of 138 cells/μl (From: R K Gupta. Pathology of Opportunistic Infections in Tropics. Jaypee; 2007)
Cryptosporidiosis Colon in a Renal Allograft Recipient
