Amebic Liver Abscess: Outcome
Discussion
We have identified distinct clinical features in patients with ALA who have different epidemiological profiles. Differences were found in groups of patients developing ALA after travel to an endemic area (TrALA) and those with ALA after living in an endemic area (En-ALA). The former were older and more likely to be male and had a more insidious onset of illness, more marked hepatomegaly, larger ALAs, and a greater proportion of multiple ALAs, including those involving the left or both lobes. These differences in clinical presentation, found in our subgroups, are consistent with differences reported previously between subgroups of patients with either acute or chronic clinical presentations of ALA. Hepatomegaly has also been found to be prevalent in patients who presented suba-cutely. The longer duration of illness in patients with Tr-ALA may result in greater hepatomegaly and larger abscesses. Despite divergent epidemiological, clinical, and radiological features in patients with ALA in different settings, overall rates of complication, recurrence and mortality were low.
It has been previously proposed that those patients acquiring ALA as endemic residents are more likely to exhibit a chronic than an acute presentation. According to this view, previous exposure and presumed immunization through infection modulate the immunological response, leading to a subacute illness in those with recurrent exposure to Entamoeba histolytica. Those with first-time exposure to Entamoeba histolytica, on the other hand, are thought to develop an “acute” clinical illness. Our findings do not support this postulate. We found that En-ALA patients had a more acute presentation with symptoms lasting for less than 14 days, while patients with Tr-ALA were most likely to have a chronic presentation, with symptoms lasting for over 1 month). Our patients and those reported earlier did, however, share notably similar clinical features in both “acute” and “chronic” presentations. Indeed, patients with chronic presentation were older and more likely to have weight loss, respiratory findings, hepatomegaly and a positive initial US than patients with an acute presentation, although only differences for weight loss and ALA size were statistically significant. Our data suggest that regardless of epidemiological background, patients with ALA tend to exhibit acute or chronic clinical presentations. Additionally, our findings raise the possibility that “acute” ALA in the En-ALA group may represent a low-level, rapidly evident, and, perhaps, rapidly clearing infection, whereas “chronic” ALA in the Tr-ALA group may represent severe, persistent infection. One alternative postulate to explain the differences in presentations between the different epidemiological groups reported here and previously (that is between the En-ALA and Tr-ALA groups), is that our patients and those reported previously could have been infected with different strains of Entamoeba histolytica, which could, in turn, be associated with divergent presentations. This postulate is consistent with a previously proposed hypothesis. Online Canadian Pharmacy
Amebic liver abcess is a relatively uncommon complication of colonic amebiasis. Although the pathogenesis of ALA is not known, it is possible that an altered immune response to Entamoeba histolytica could contribute to the development of ALA. Alcohol consumption in particular is an important potential immunosuppressive factor, and it has been reported in up to 80% of patients with En-ALA. Alcohol may make the liver more susceptible to Entamoeba histolytica infection by directly impairing Kupffer cell function in the liver or by hindering the cellular and humoral immunologic response to Entamoeba histolytica. In this series, over 40% of patients had a history of heavy alcohol consumption, and consumption was highest in patients with Tr-ALA (69%).
Experimental studies have shown impaired immunity to be an important factor in the pathogenesis of ALA. Immunosuppression after thymectomy or splenectomy in animals results in an increased incidence of ALA. Stimulation of the immune system with bacillus Cal-mette-GuErin (BCG), however, reduces the risk of developing ALA.8 Furthermore, iatrogenic exacerbation of ALA in patients unsuspected of harboring ALA has been documented after the administration of corticosteroids. In our series, of the 56 patients reported, 16 (29%) had not been placed at risk for ALA by either endemic origin or travel history (N-ALA). Furthermore, 10 of those 16 patients with N-ALA (63%) had an associated condition compatible with severe immunosuppression. These patients had significant medical conditions, such as HIV infection (38%), malnourish-ment with severe hypoalbuminemia (25%), chronic infections, namely tuberculosis and syphilis (25%), heavy alcohol use (25%), hepatitis (13%), or had undergone splenectomy (6%). generic Imitrex online
Together, our data and the experimental data raise the possibility that an immunocompromised state could be a risk factor for the development of ALA. It is also possible, however, that invasive amebiasis itself leads to immunosuppression.
Whether HIV infection is a risk factor for development of ALA is unknown. We identified six HIV-infected patients with ALA, two of whom had AIDS by standard criteria. All of the HIV-infected patients were born in the United States, and none had a history of travel to an endemic area. All six were homosexual. Homosexual men are known to have an increased incidence of colonic amebiasis due to increased fecal-oral contact. During the 1970s, the incidence of amebiasis increased by 8000% in homosexual men in San Francisco over a 10-year period, and 40% of patients with amebiasis in a New York hospital were homosexual. Thus, a homosexual lifestyle appears to facilitate the transmission of Entamoeba histolytica. Whether HIV infection in conjunction with the enhanced transmission of Entamoeba histolytica increases the risk of ALA remains an open question requiring further study. viagra oral jelly
The relationship between HIV/AIDS and ALA may be important. In the last five years of our series, one third of all patients with ALA were HIV-infected, and it is notable that three of the six HIV-infected patients were found to be HIV-positive after the ALA was diagnosed (including 2 patients who were found to have AIDS by CD4 criteria). It has been proposed that there could be an increase in extra-intestinal amebiasis, including ALA, in HIV-infected patients due to the emergence of less virulent strains. Although our data suggest that this may be possible, a population-based, epidemiological study comparing an HIV-infected population to a population with travel-related risk and to a population without risk is required. Furthermore, such a study could explore possible differences between strains of Entamoeba, such as Entamoeba histolytica, the “pathogenic” species, and Entamoeba dispar, the “nonpathogenic” species. This study could also investigate the conversion of nonpathogenic strains, presumable prevalent in many homosexual populations, into pathogenic strains, which has been postulated to occur in vitro. In any case, the presence of a space-occupying hepatic lesion in an HIV-infected patient should indicate the possible presence of ALA, and the patient should be managed accordingly.
In conclusion, travel to and origin in an endemic area are important risk factors for the development of ALA, and patients in each of these groups appear to have distinct clinical features. In addition, a subset comprising one third of patients in this series had no travel to or origin in an endemic area, but appeared to be susceptible to development of ALA. In this group, the majority had associated immunosuppressive conditions, of which HIV infection was the most common. These data raise the possibility that impaired host immunity may be an important factor in the pathogenesis of ALA. Moreover, from a clinical management perspective, the rinding of an ALA in a patient without travel or endemic risk factors should suggest the possibility of a compromised immune system. Viagra Professional