Toddy consumption and amoebic liver abscess in India: An unexplored link

Amebic liver abscess: An update

Amebic liver abscess (ALA) is still a common problem in the tropical world, where it affects over three-quarters of patients with liver abscess. It is caused by an anaerobic protozoan Entamoeba hystolytica, which primarily colonises the cecum. It is a non-suppurative infection of the liver consisting primarily of dead hepatocytes and cellular debris. People of the male gender, during their reproductive years, are most prone to ALA, and this appears to be due to a poorly mounted immune response linked to serum testosterone levels. ALA is more common in the right lobe of the liver, is strongly associated with alcohol consumption, and can heal without the need for drainage. While majority of ALA patients have an uncomplicated course, a number of complications have been described, including rupture into abdomino-thoracic structures, biliary fistula, vascular thrombosis, bilio-vascular compression, and secondary bacterial infection. Based on clinico-radiological findings, a classification system for ALA has emerged recently, which can assist clinicians in making treatment decisions. Recent research has revealed the role of venous thrombosis-related ischemia in the severity of ALA. Recent years have seen the development and refinement of newer molecular diagnostic techniques that can greatly aid in overcoming the diagnostic challenge in endemic area where serology-based tests have limited accuracy. Metronidazole has been the drug of choice for ALA patients for many years. However, concerns over the resistance and adverse effects necessitate the creation of new, safe, and potent antiamebic medications. Although the indication of the drainage of uncomplicated ALA has become more clear, high-quality randomised trials are still necessary for robust conclusions. Percutaneous drainage appears to be a viable option for patients with ruptured ALA and diffuse peritonitis, for whom surgery represents a significant risk of mortality. With regard to all of the aforementioned issues, this article intends to present an updated review of ALA.

Amebic liver abscess: Clinico-radiological findings and interventional management

In its classic form, amebic liver abscess (ALA) is a mild disease, which responds dramatically to antibiotics and rarely requires drainage. However, the two other forms of the disease, i.e., acute aggressive and chronic indolent usually require drainage. These forms of ALA are frequently reported in endemic areas. The acute aggressive disease is particularly associated with serious complications, such as ruptures, secondary infections, and biliary communications. Laboratory parameters are deranged, with signs of organ failure often present. This form of disease is also associated with a high mortality rate, and early drainage is often required to control the disease severity. In the chronic form, the disease is characterized by low-grade symptoms, mainly pain in the right upper quadrant. Ultrasound and computed tomography (CT) play an important role not only in the diagnosis but also in the assessment of disease severity and identification of the associated complications. Recently, it has been shown that CT imaging morphology can be classified into three patterns, which seem to correlate with the clinical subtypes. Each pattern depicts its own set of distinctive imaging features. In this review, we briefly outline the clinical and imaging features of the three distinct forms of ALA, and discuss the role of percutaneous drainage in the management of ALA.

Venous thrombosis and segmental hypoperfusion in amebic liver abscess: MDCT demonstration and its implications

PURPOSE

To report venous thrombosis and associated perfusion defect in amebic liver abscess (ALA) using MDCT.

METHOD

MDCT images of 62 patients with ALA were reviewed for venous thrombosis and associated perfusion abnormalities.

RESULT

The study found 43 (69%) patients with venous thrombosis: portal vein thrombosis (PVT) occurred in 39, hepatic vein thrombosis (HVT) in 37 and inferior vena cava (IVC) thrombosis in 4. Combined PVT and HVT occurred in 33 (77%) patients. The portal vein thrombi remained localized in subsegmental branches in 25 patients and extended to segmental branches in 14. The hepatic vein thrombi were confined to peripheral branches in 18 patients; they progressed to the main trunk in 19 and to the IVC in 4. A wedge-shaped hypoattenuating zone suggesting ischemia was identified in 33 (77%) patients in portal phase: 31 had combined PVT and HVT, 2 had HVT alone, but none had PVT alone. It occurred significantly more often with combined PVT and HVT than HVT alone (p = 0.05). Arterial phase enhancement occurred in 2 of 13 patients with multiphasic CT. All patients were symptomatic despite medical therapy and therefore required percutaneous drainage. About half of the patients were identified with ruptured abscesses. Segmental atrophy was observed in seven of nine patients who underwent follow-up CT.

CONCLUSION

Combined PVT and HVT commonly occur with ALA and often manifests as segmental hypoperfusion in portal venous phase, indicating ischemia. The detection of such events by CT may be indicative of severe disease that requires aggressive management involving percutaneous drainage.

Venous thrombosis and segmental hypoperfusion in amebic liver abscess: MDCT demonstration and its implications

PURPOSE

To report venous thrombosis and associated perfusion defect in amebic liver abscess (ALA) using MDCT.

METHOD

MDCT images of 62 patients with ALA were reviewed for venous thrombosis and associated perfusion abnormalities.

RESULT

The study found 43 (69%) patients with venous thrombosis: portal vein thrombosis (PVT) occurred in 39, hepatic vein thrombosis (HVT) in 37 and inferior vena cava (IVC) thrombosis in 4. Combined PVT and HVT occurred in 33 (77%) patients. The portal vein thrombi remained localized in subsegmental branches in 25 patients and extended to segmental branches in 14. The hepatic vein thrombi were confined to peripheral branches in 18 patients; they progressed to the main trunk in 19 and to the IVC in 4. A wedge-shaped hypoattenuating zone suggesting ischemia was identified in 33 (77%) patients in portal phase: 31 had combined PVT and HVT, 2 had HVT alone, but none had PVT alone. It occurred significantly more often with combined PVT and HVT than HVT alone (p = 0.05). Arterial phase enhancement occurred in 2 of 13 patients with multiphasic CT. All patients were symptomatic despite medical therapy and therefore required percutaneous drainage. About half of the patients were identified with ruptured abscesses. Segmental atrophy was observed in seven of nine patients who underwent follow-up CT.

CONCLUSION

Combined PVT and HVT commonly occur with ALA and often manifests as segmental hypoperfusion in portal venous phase, indicating ischemia. The detection of such events by CT may be indicative of severe disease that requires aggressive management involving percutaneous drainage.

Entamoeba histolytica and amoebic liver abscess in northern Sri Lanka: a public health problem

Entamoeba histolytica (E. histolytica) is a facultative protozoan parasite implicated in amoebic liver abscesses (ALA), the most common extraintestinal manifestation of this infection. E. histolytica is endemic to sub-tropical and tropical countries and has been a major public health concern in northern Sri Lanka (SLK) for the last three decades. This has been attributed to a multitude of factors such as poor sanitation, hygiene, male sex, middle age, overcrowding, unsanitary practices in the production of indigenous alcoholic beverages, and alcohol consumption. Additionally, while rates of E. histolytica have declined substantially throughout the rest of the island, largely due to better infrastructure, it remains pervasive in the northern peninsula, which is generally less developed. Infection arises primarily from fecal-oral transmission through the consumption of contaminated drinking water containing cysts. Upon ingestion, cysts multiply into trophozoites and colonize the host colonic mucosa using lectin and cysteine proteases as virulence factors, leading to host invasion. Symptoms occur along a spectrum, from asymptomatology, to pyrexia, abdominal cramping, and amoebic dysentery. Colonization of the colon results in the formation of distinct flask-shaped ulcers along the epithelium, and eventual penetration of the lamina propria via the production of matrix metalloproteinases. ALA then develops through trophozoite migration via the mesenteric hepatic portal circulation, where microabscesses coalesce to form a single, large right-lobe abscess, commonly on the posterior aspect. The progression of infection to invasive disease is contingent on the unique interplay between host and pathogen factors, such as the strength of host-immunity to overcome infection and inherent pathogenicity of the Entamoeba species. As a preventable illness, E. histolytica complications such as ALA impose a significant burden on the healthcare system. This mini-review highlights epidemiological trends, risk factors, diagnostic modalities, treatment approaches, and opportunities for prevention of E. histolytica-induced ALA, to help address this endemic problem on the island of SLK.