Amebic liver abscess and human immunodeficiency virus infection: a report of three cases

Multiple Amoebic Liver Abscess As Initial Manifestation in Hiv Sero-Positive Male

Amoebic liver abscess is the most frequent extra-intestinal manifestation of Entamoeba histolytica infection. Immunosuppression is known to predispose to amoebic liver abscess. Although amoebic liver abscess is seen more commonly in patients of Human-Immunodeficiency virus (HIV), first presentation of HIV sero-positive patient as multiple liver abscess is quite uncommon.The author reports an unusual case of multiple liver abscesses in an HIV seropositive patient. This middle aged male with history of multiple unprotected sexual encounters presented with spasmodic abdominal pain, fever, diarrhoea and weight loss along with generalised ill-health and painful liver enlargement. HIV-1 serology was found to be reactive. Imaging revealed an enlarged liver with multiple, irregular, hypoechoic foci characteristic of abscesses. Amoebic aetiology was later confirmed by percutaneous aspiration and microscopy. Administration of appropriate chemotherapeutics along with institution of antiretroviral therapy led to both clinical resolution as well as disappearance of lesions.

Amebic liver abscess: fine needle aspiration diagnosis

OBJECTIVE

To describe the findings in fine needle aspiration (FNA) of an amebic liver abscess (ALA).

STUDY DESIGN

Seven patients (6 men and 1 woman between 52 and 60 years of age) treated for amebic dysentery with multiple liver lesions were selected for ultrasound (US)-guided FNA. The clinical differential diagnosis was malignancy. Abdominal US of the patients revealed multiple, variably sized, well-defined, hypoechoic, cystic liver lesions. FNA of these lesions was performed.

RESULTS

Smears of the aspirated material showed necrotic material with mixed inflammatory cells and Entamoeba histolytica trophozoites consisting of round blue bodies with well-defined borders containing a single, eccentrically located nucleus with central karyosome and engulfed red blood cells in the cytoplasm. There were also Charcot-Leyden crystals. ALA was diagnosed.

CONCLUSION

FNA can yield the correct diagnosis of ALA and allows early initiation of treatment. ALA should be considered in the differential diagnosis of space-occupying lesions of the liver.

Amebiasis in HIV-1-infected Japanese men: clinical features and response to therapy

Invasive amebic diseases caused by Entamoeba histolytica are increasing among men who have sex with men and co-infection of ameba and HIV-1 is an emerging problem in developed East Asian countries. To characterize the clinical and epidemiological features of invasive amebiasis in HIV-1 patients, the medical records of 170 co-infected cases were analyzed retrospectively, and E. histolytica genotype was assayed in 14 cases. In this series of HIV-1-infected patients, clinical presentation of invasive amebiasis was similar to that described in the normal host. High fever, leukocytosis and high CRP were associated with extraluminal amebic diseases. Two cases died from amebic colitis (resulting in intestinal perforation in one and gastrointestinal bleeding in one), and three cases died from causes unrelated to amebiasis. Treatment with metronidazole or tinidazole was successful in the other 165 cases. Luminal treatment was provided to 83 patients following metronidazole or tinidazole treatment. However, amebiasis recurred in 6 of these, a frequency similar to that seen in patients who did not receive luminal treatment. Recurrence was more frequent in HCV-antibody positive individuals and those who acquired syphilis during the follow-up period. Various genotypes of E. histolytica were identified in 14 patients but there was no correlation between genotype and clinical features. The outcome of metronidazole and tinidazole treatment of uncomplicated amebiasis was excellent even in HIV-1-infected individuals. Luminal treatment following metronidazole or tinidazole treatment does not reduce recurrence of amebiasis in high risk populations probably due to amebic re-infection.

Amebiasis is usually transmitted by ingestion of contaminated food or water in developing countries. Recently, however, increased risk for amebiasis among men who have sex with men (MSM) due to oral-anal sexual contact was reported in developed countries, resulting in growing concern on amebiasis in HIV-1-infected MSM. The recommended treatment of amebiasis is metronidazole or tinidazole, followed by a luminal agent to eliminate intestinal cyst colonization. However, the efficacy of luminal treatment in preventing recurrence has not been assessed yet. In this study, we analyzed the medical records of 170 patients with amebiasis and HIV-1 co-infection. Treatment with metronidazole or tinidazole was excellent whereas luminal treatment did not reduce the frequency of recurrence of amebiasis. Recurrence was more frequent in those MSM with signs of sexual activity such as syphilis infection. Luminal treatment following metronidazole or tinidazole treatment does not reduce recurrence of amebiasis in high risk populations.

Liver abscess in neonates

INTRODUCTION

Liver abscesses are rare in neonates with the majority resulting from an ascending infection via the umbilical and portal veins, haematogenous spread, or via the biliary tree, or via direct contiguous spread from neighbouring structures. They may present in unusual ways often presenting with ongoing sepsis and resulting in diagnostic difficulties. We present the clinical and radiological findings on six neonates with hepatic abscesses and underline the association with misplacement of umbilical line, association with hypertonic glucose infusions and TPN.

METHODS

A retrospective chart review made of six patients diagnosed with hepatic abscesses between 2000 and 2006. Methods included clinical and radiological review as well as evaluation of potential risk factors.

RESULTS

Five of the six patients with neonatal liver abscess were of low birth weight and low gestational age (range 30-34 weeks), but one was post mature (42 weeks). Sex distribution was equal and two were HIV exposed (mother positive), two HIV negative with two having an unknown HIV status. Clinical signs included raised infective markers (CRP) (6) and non-specific signs of septicaemia (4), but a tender hepatomegaly (1) and abdominal distension with ileus (1) were also noted. Five were right-sided abscesses (2 associated with malposition of umbilical line) and one central in position. Predisposing factors included association with a misplaced umbilical line with high concentration glucose infusions (2) and tuberculosis was later diagnosed in one. Infective markers (CRP) remained high with positive blood cultures persisting in all. Causative organisms included Klebsiella (3) Staphylococcus (3) [one a multi-resistant staphylococcus (MRSA)], Gonococcus (1) and Enterobacter (1). Abdominal X-ray demonstrated a mal-positioned umbilical line in three patients (50%). Ultrasound (US) proved a reliable method of diagnosis although some difficulty was encountered in interpreting resolving abscesses and trans-diaphragmatic spread occurred in one. Three patients (50%) responded to antibiotic therapy alone, but interventional drainage was required in the remainder. Needle aspiration was successful in two of these, but one further patient had a radiologically placed pigtail drainage, but later required open drainage. This patient then developed trans-diaphragmatic spread and empyema requiring thoracoscopic decortication.

CONCLUSION

Neonatal hepatic abscesses are rare but should enter the differential diagnosis of a neonate with ongoing sepsis. This study serves to draw attention to their association with misplaced central (umbilical) catheters. Failure to respond to antibiotic therapy necessitates interventional drainage.

Association between amebic liver abscess and human immunodeficiency virus infection in Taiwanese subjects

Purpose

Invasive amebiasis is an emerging parasitic disorder in Taiwan, especially in patients diagnosed with human immunodeficiency virus (HIV) infection. Thirty-three Taiwanese subjects with amebic liver abscess (ALA) were examined and a possible correlation between ALA and HIV infection was investigated.

Results

Among ALA patients, the proportion of HIV-positive individuals increased during the study period. ALA was the first major clinical presentation in 54% of HIV patients with ALA. Overall, 58% (14/24) of HIV-infected patients had a CD4+ count > 200 cells/μL and 82.1% (23/28) had no concurrent opportunistic infection or other evidence of HIV infection. There was no marked difference in clinical characteristics between HIV-positive and HIV-negative ALA patients except the level of leukocytosis.

Conclusion

While the clinical characteristics described herein cannot be used to determine whether ALA patients have HIV infection, routine HIV testing is recommended in patients with ALA, even in the absence of HIV symptoms.

Increased risk for Entamoeba histolytica infection and invasive amebiasis in HIV seropositive men who have sex with men in Taiwan

Background

Incidence of Entamoeba histolytica infection and clinical manifestations and treatment response of invasive amebiasis (IA) in HIV-infected patients have rarely been investigated before.

Methodology/Principal Findings

At the National Taiwan University Hospital, medical records of HIV-infected patients who received a diagnosis of IA between 1994 and 2005 were reviewed. The incidence of amebiasis was investigated in serial blood and stool samples from 670 and 264 HIV-infected patients, respectively, using serological and specific amebic antigen assays. DNA extracted from stool samples containing E. histolytica were analyzed by PCR, sequenced, and compared. Sixty-four (5.8%) of 1,109 HIV-infected patients had 67 episodes of IA, and 89.1% of them were men having sex with men (MSM). The CD4 count at diagnosis of IA was significantly higher than that of the whole cohort (215 cells/µL vs. 96 cells/µL). Forty episodes (59.7%) were liver abscesses, 52 (77.6%) colitis, and 25 (37.3%) both liver abscesses and colitis. Fever resolved after 3.5 days of metronidazole therapy (range, 1–11 days). None of the patients died. The incidence of E. histolytica infection in MSM was higher than that in other risk groups assessed by serological assays (1.99 per 100 person-years [PY] vs. 0 per 100 PY; p<0.0001) and amebic antigen assays (3.16 per 100 PY vs. 0.68 per 100 PY; p = 0.12). In multiple logistic regression analysis, only MSM was significantly associated with acquisition of E. histolytica infection (adjusted odds ratio, 14.809; p = 0.01). Clustering of E. histolytica isolates by sequencing analyses from geographically-unrelated patients suggested person-to-person transmission.

Conclusions/Significance

HIV-infected MSM were at significantly higher risk of amebiasis than patients from other risk groups. Despite immunosuppression, amebic liver abscesses and colitis responded favorably to treatment.

Entamoeba histolytica, morphologically identical to but genetically different from E. dispar and E. moshkovskii, is the causative agent of amebiasis. Recently there have been reports of increased risk for amebiasis among men who have sex with men (MSM) due to oral-anal sexual contact in several developed countries. In this longitudinal follow-up study, the incidence of amebiasis was determined among HIV-infected patients using serological and specific amebic antigen assays. DNA extracted from stool samples containing E. histolytica were analyzed by PCR, sequenced, and compared. Clinical manifestations and treatment response of invasive amebiasis in HIV-infected patients were reviewed. The results demonstrated that HIV-infected MSM were at significantly higher risk of amebiasis than patients from other risk groups. Clustering of E. histolytica isolates by sequencing analyses from geographically unrelated patients suggested person-to-person transmission. Despite immunosuppression, amebic liver abscesses and colitis responded favorably to metronidazole therapy. It is important to investigate in areas of high incidence of both amebiasis and HIV (sub-Saharan Africa) how generalizable these findings are.

Amebiasis cutis revisited

BACKGROUND

Amebiasis cutis (AC) is reported infrequently. This study assesses the clinicopathological spectrum, co-existent visceral involvement and impact of human immunodeficiency virus (HIV) co-infection on AC.

METHODS

An 8-year prospective clinicopathological evaluation of patients with AC.

RESULTS

Thirty-one biopsies of ulcers, fistulae, fissures, abscesses, polypoid and warty lesions in perianal, penile, scrotal, vulval, buttock, chest and abdominal wall sites were evaluated. Of these, 11 had a 'superficial' (superficial AC) and 20 a 'deep' (deep AC), histopathological pattern. Superficial AC showed predominant epidermal spongiosis, liquefactive necrosis, ulceration and fissures with hematophagous amebic trophozoites (HATs). Deep AC had confluent deep dermal and subcutaneous liquefactive, coagulative or suppurative necrosis and HATs. Seven biopsies showed vasculitis or thrombosis with luminal HATs.

OUTCOME

Fourteen patients died; 9 had concomitant visceral amebiasis, 5 had other co-infections. Six who died were HIV seropositive, three were seronegative; all had deep AC. Of the 17 survivors, 11 (8 HIV positive) had superficial AC that healed with metronidazole treatment; the remaining 6 (one HIV seropositive) required additional surgical intervention.

CONCLUSION

Deep AC is predictive of co-existent, contiguous visceral disease. The effective management, histopathological mimickers and diagnostic pitfalls of superficial and deep AC differ. The outcome in HIV-infected patients is dependent on co-existent systemic diseases.

Amoebic hepatic abscesses in an HIV-positive patient

Herein we report the case of hepatic amoebic abscesses in an HIV-positive Italian seaman with a history of promiscuous heterosexual intercourse. In October 2004, the patient was hospitalized because of fever and recurring abdominal pain. Abdominal ultrasonography revealed six hepatic hypoechoid oval lesions with hyperechoid margins. Stool samples were negative for parasites and bacteria, and serology for Entamoeba histolytica was also negative. Therapy with meropenem plus levofloxacin was initiated. After a partial resolution of clinical symptoms and reduction of three hepatic lesions, the patient was again hospitalized in December 2004, because of recurring intense pain at the right hypochondrium and fever. At this time, one hepatic lesion at the sixth segment was enlarged, two lesions were unchanged, and the remaining three smaller abscesses were resolved. Serum antibodies for E. histolytica and amoebic antigens on the largest abscess drainage were positive; moreover, E. histolytica was also identified on drainage fluid with polymerase chain reaction (PCR). Therapy with metronidazole followed by paromomycin improved both symptoms and radiographic images. This case report suggests that in HIV-infected patients, invasive amoebiasis should be considered and atypical aspects, such as multiple hepatic lesions, delayed positivity of serology for E. histolytica, and possible bacterial superinfection should be evaluated.

The anti-amoebic activity of some medicinal plants used by AIDS patients in southern Thailand

The anti-amoebic activities of chloroform, methanol and water extracts from 12 Thai medicinal plants (39 extracts) commonly used by AIDS patients in southern Thailand were screened, at a concentration of 1,000 microg/ml, against Entamoeba histolytica strain HTH-56:MUTM and strain HM1:IMSS growing in vitro. The extracts were incubated with 2x10(5) E. histolytica trophozoites/ml of medium at 37 degrees C under anaerobic conditions for 24 h. The cultures were examined with an inverted microscope and scored (1-4) according to the appearance and numbers of the trophozoites. The extracts that caused inhibition were selected and retested using the same conditions but with concentrations that ranged from 31.25 to 1,000 microg/ml using E. histolytica strain HM1:IMSS, and the IC(50) values for each extract were calculated. The chloroform extracts from Alpinia galanga (IC(50) 55.2 microg/ml), Barleria lupulina (IC(50) 78.5 microg/ml), Boesenbergia pandurata (IC(50) 45.8 microg/ml), Piper betle (IC(50) 91.1 microg/ml) and Piper chaba (IC(50) 71.4 microg/ml) and the methanol extract from B. pandurata (IC(50) 57.6 microg/ml) were all classified as "active", i.e. with an IC(50) of less than 100 microg/ml, whereas those from Murraya paniculata (IC(50) 116.5 microg/ml) and Zingiber zerumbet (IC(50) 196.9 microg/ml) were classified as being "moderately active". The IC(50) of a standard drug, metronidazole, was 1.1 microg/ml.

The pathogenicity of Entamoeba histolytica is related to the capacity of evading innate immunity

The host and parasite factors that influence susceptibility to Entamoeba histolytica infection and disease are not well understood. Entamoeba histolytica pathogenicity has been considered by focusing principally on parasite rather than host factors. Thus, research has concentrated on explaining the molecular differences between pathogenic E. histolytica and non-pathogenic E. dispar. However, the amoeba molecules considered most important for host tissue destruction (amoebapore, galactose/N-acetyl galactosamine inhibitable lectin, and cysteine proteinases) are present in both pathogenic E. histolytica and non-pathogenic E. dispar. In addition, the genetic differences in pathogenicity among E. histolytica isolates are unlikely to completely explain the different outcomes of infection. Considering that the principal difference between pathogenic and non-pathogenic amoebas lies in their surface coats, we propose that pathogenicity of the amoebas is related to the composition and properties of the surface coat components (or pathogen-associated molecular patterns, PAMPs), and the ability of innate immune response to recognize these components and eliminate the parasite. According to this hypothesis, a key feature that may distinguish pathogenic (E. histolytica) from non-pathogenic (E. dispar) strains is whether or not they can overcome innate immune defences. A corollary of this hypothesis is that in susceptible individuals the PAMPs are either not recognized or they are recognized by a set of Toll-like receptors (TLRs) that leads to an inflammatory response. In both cases, the result is tissue damage. On the contrary, in resistant individuals the innate/inflammatory response, induced through the activation of a different set of TLRs, eliminates the parasite.

Hepatic pathology in AIDS: a pathological study from Mumbai, India

OBJECTIVES

To assess the spectrum of hepatic disorders in AIDS, liver specimens from 171 patients (155 autopsies and 16 biopsies) were reviewed.

METHODS

A retrospective and prospective study of 171 autopsy and biopsy specimens was carried out at a tertiary level hospital in Mumbai, India.

RESULTS

Of the patients included in the study, 127 (74%) were male and 44 (26%) were female. The heterosexual route was the predominant mode of HIV transmission, identified in 163 (95%) patients. A total of 99 of 171 patients (58%) showed significant pathological lesions, and the most common pathological processes involving the liver appeared to be secondary to infections. None of our patients showed isolated infectious diseases of the liver. The spectrum of liver diseases identified was as follows: tuberculosis in 70 patients (41%), cryptococcosis in eight (5%), cytomegalovirus infection in six (3%), hepatitis B infection in five (3%), candidiasis in one (0.5%), malaria in one (0.5%), cirrhosis in six (3%), amyloidosis in one (0.5%) and primary hepatic lymphoma in one (0.5%).

CONCLUSIONS

AIDS patients were found to have a high prevalence of underlying hepatic abnormalities. The spectrum of disease among patients with AIDS in India differs from that in developed countries. Our results suggest that hepatic tuberculosis is more common in AIDS than previously recognized, and that liver specimens should be examined routinely for the presence of acid-fast bacilli.

Pyogenic and amebic liver abscesses

Pyogenic and amebic liver abscesses are the two most common hepatic abscesses. Amebic abscesses are more common in areas where Entamoeba histolytica is endemic, whereas pyogenic abscesses are more common in developed countries. Pyogenic abscess severity is dependent on the bacterial source and the underlying condition of the patient. Amebic liver abscess is more prevalent in individuals with suppressed cell-mediated immunity, men, and younger people. The right lobe of the liver is the most likely site of infection in both types of hepatic abscess. Patients usually present with a combination of fever, right-upper-quadrant abdominal pain, and hepatomegaly. Jaundice is more common in the pyogenic abscess. The diagnosis is often delayed and is usually made through a combination of radiologic imaging and microbiologic, serologic, and percutaneous techniques. Treatment involves antibiotics along with percutaneous drainage or surgery.

Amebic liver abscess

Amebic liver abscess is the most common extraintestinal manifestation of infection with Entamoeba histolytica, and it is associated with significant morbidity and mortality. In this article the most recent available information is reviewed relating to epidemiology, pathogenesis, presentation, diagnosis, and treatment. We reviewed thousands of cases of amebic liver abscess in the medical literature and present that information as it pertains to mortality, gender, anatomic location of abscesses, and clinical signs and symptoms.

Laboratory diagnosis of amebiasis

The detection of Entamoeba histolytica, the causative agent of amebiasis, is an important goal of the clinical microbiology laboratory. To assess the scope of E. histolytica infection, it is necessary to utilize accurate diagnostic tools. As more is discovered about the molecular and cell biology of E. histolytica, there is great potential for further understanding the pathogenesis of amebiasis. Molecular biology-based diagnosis may become the technique of choice in the future because establishment of these protozoa in culture is still not a routine clinical laboratory process. In all cases, combination of serologic tests with detection of the parasite (by antigen detection or PCR) offers the best approach to diagnosis, while PCR techniques remain impractical in many developing country settings. The detection of amebic markers in serum in patients with amebic colitis and liver abscess appears promising but is still only a research tool. On the other hand, stool antigen detection tests offer a practical, sensitive, and specific way for the clinical laboratory to detect intestinal E. histolytica. All the current tests suffer from the fact that the antigens detected are denatured by fixation of the stool specimen, limiting testing to fresh or frozen samples.

Pathogenesis of amebiasis

It is an exciting time in the study of Entamoeba histolytica. Over the past two years, the natural history and burden of disease in humans has been redefined, mucosal immune responses associated with protection identified, and the developmental regulation of encystation outlined. The number of genes sequenced has increased from a few hundred to a few thousand, and study of the genome structure is revealing unusual repetitive elements and plasticity. DNA microarrays promise the first ability to examine global patterns of mRNA abundance. The mechanism of transcriptional control via histone modifications and sequence-specific DNA-binding proteins are to be delineated. Advances in cell biology are providing new insights into invasion through the intestinal epithelium.

A note on clinical presentations of amebic liver abscess: an overview from 62 Thai patients

BACKGROUND

Amebic liver abscess is a tropical disease with a wide spectrum of clinical presentations. Given the often nonspecific nature of the complaints related to amebic abscess, a retrospective review of patients with confirmed disease to recognize the most common patterns of presentation is useful. Here, we study the clinical presentations of 62 Thai patients with amebic liver abscess. We also compare the clinical presentations of Anti HIV seronegative and Anti HIV seropositive patients.

METHODS

A retrospective case review was carried out for 62 Thai patients who had been diagnosed with amebic liver abscess. Clinical information was collected, including symptoms and signs, location and number of abscesses. The Anti HIV serology laboratory investigation was also reviewed.

RESULTS

According to our study, the common clinical symptoms and signs are abdominal pain (85.5 %), fever and chills (74.2 %), and abdominal tenderness (69.4 %). The location of the abscess was predominantly in the right lobe (74.2 %), and most of patients had a single abscess (77.4 %). Similar trends in clinical presentations were observed in both Anti HIV seropositive and Anti HIV seronegative subjects.

CONCLUSIONS

In conclusion, the clinical presentations of our amebic liver abscess patients were similar to those in previous reports. A similarity to those in the pyogenic liver abscess patients can be observed. Nevertheless, we could not detect important significant differences in the clinical presentations between Anti HIV seropositive and Anti HIV seronegative groups of patients.

Thoracic amebiasis

Pleuropulmonary amebiasis is the common and pericardial amebiasis the rare form of thoracic amebiasis. Low socioeconomic conditions, malnutrition, chronic alcoholism, and ASD with left to right shunt are contributing factors to the development of pulmonary amebiasis. Although no age is exempt, it commonly occurs in patients aged 20 to 40 years, with an adult male to female ratio of 10:1. Children rarely develop thoracic amebiasis: when it does occur there is an equal sex distribution. The infection usually spreads to the lungs by extension of an amebic liver abscess. Infection may pass to the thorax directly from the primary intestinal lesion through hematogenous spread, however. Lymphatic spread is one possible route. Inhalation of dust containing cysts and aspiration of cysts or trophozoites of E histolytica in the lungs are some other hypothetical routes. The lung is the second most common extraintestinal site of amebic involvement after the liver. Usually the lower lobe, and sometimes the middle lobe of the right lung, are affected, but it may affect any lobe of the lungs. The patient develops fever and right upper quadrant pain that is referred to the tip of the right shoulder or in between the scapula. Hemophtysis is common. The diagnosis of thoracic amebiasis is suggested by the combination of an elevated hemidiaphragm (usually right), hepatomegaly, pleural effusion, and involvement of the right lung base in the form of haziness and obliteration of costophrenic and costodiaphragmatic angles. Infection is usually extended to the thorax by perforation of a hepatic abscess through the diaphragm and across an obliterated pleural space, producing pulmonary consolidation, abscesses, or broncho-hepatic fistula. Empyema develops when a liver abscess ruptures into the pleural space. Rarely, a posterior amebic liver abscess can burst into the inferior vena cava and develop an embolism of the inferior vena cava and thromboembolic disease of the lungs with congestive cardiac failure or corpulmonale. Diagnosis by finding E histolytica in stool specimens is of limited value. In a limited number of cases amebae might be found in aspirated pus or expectorated sputum. "Anchovy sauce-like" pus or sputum may be found. Presence of bile in sputum indicates that the pus is of liver origin. Serological tests are of immense value in diagnosis. Liver enzymes are usually normal and neutrophilic leucocytosis may or may not be found. ESR is invariably elevated. Anti-amebic antibodies can be detected by ELISA, IFAT, and IHA. Amebic antigen can be detected from serum and pus by ELISA. Detection of Entamoeba DNA in pus or sputum may be a sensitive and specific method. Pleuropulmonary amebiasis is easily confused with other illnesses and is treated as pulmonary TB, bacterial lung abscesses, and carcinoma of the lung. A single drug regimen with metronidazole with supportive therapy usually cures patients without residual anomalies. Aspiration of pus from empyema thoracis may be needed for confirmation and therapeutic purposes. The pericardium is usually involved by direct extension from the amebic abscess of the left lobe of the liver, sometimes from the right lobe of the liver, and rarely from the lungs or pleura. An initial accumulation of serous fluid due to reactive pericarditis followed by intrapericardial rupture may develop either (1) acute onset of severe symptoms with chest pain, dyspnea, and cardiac tamponade, shock, and death, or (2) progressive effusion with thoracic cage pain, progressive dyspnea, and fever. Chest radiograph, ultrasound examination, and CT scan usually confirm the presence of a liver abscess in continuity with the pericardium and fluid within the pericardial sac with or without the fistulous tract. Echocardiography may demonstrate fluid in the pericardial cavity. Patients should be cared for in the ICU and ambecides should be started without delay. Pericardiocentesis usually confirms the diagnosis and improves the general condition of the patient. Aspiration of the accumulated fluid should be performed urgently in cardiac tamponade; repeated aspiration may be needed. Surgical drainage should be done if needed. Acanthamoeba, a free-living ameba, may also infect the lungs in the form of pulmonary nodular infiltration and pulmonary edema in association with amebic meningoencephalitis in immunocompromised patients. It usually spreads to the meninges of the brain by way of the blood from its primary lesion in the lung or skin. Early diagnosis and institution of treatment may be life saving for these patients. A literature review shows that HIV/AIDS patients are not prone to infection with E histolytica. It is now clear that there are an increasing number of HIV-seropositive patients among amebic liver abscess patients, however, which suggests that although the incidence of intestinal infection is not high among HIV-seropositive or AIDS patients they are more susceptible to an invasive form of the disease.

Entamoeba histolytica: Clinical Update and Vaccine Prospects

Amebiasis is extraordinarily common in children of the developing world. This realization has come from application of diagnostic techniques that distinguish the nonpathogenic parasite Entamoeba dispar from Entamoeba histolytica. E. histolytica infection is found in children with dysentery, diarrhea, and in many cases in children with no gastrointestinal symptoms. Genetically distinct strains of E. histolytica exist but evidence is too preliminary to judge if some strains are more virulent than others. A provocative study from Tanzania has shown that pregnant women with HIV infection who are coinfected with E. histolytica are at greater risk of delivering a low birth weight infant. Perhaps the most exciting new data is the identification of acquired immunity to recurrent E. histolytica infection. Acquired immunity is linked to a mucosal immune response against a major virulence factor of the parasite, a Gal/GalNAc lectin responsible for adherence and killing of the host. Prospects for a vaccine are thus brightening at the same time that the true burden of disease is comprehended.