Liver infections: bacterial, fungal and parasitic
- Lesion
Bacteria, amoebae, worms and fungi can reach the liver through bile, blood or the gut and form abscesses, cysts, scars or granulomas.
What it is
Besides hepatitis viruses, many organisms involve the liver. Bacteria reach it through obstructed bile ducts (ascending cholangitis), the portal vein (from intestinal infections), the hepatic artery (sepsis) or direct spread, producing pyogenic abscesses. Entamoeba histolytica produces an amebic abscess. Echinococcus forms hydatid cysts; Schistosoma eggs cause periportal fibrosis; liver flukes live in bile ducts and raise cholangiocarcinoma risk. Mycobacteria and fungi such as Histoplasma form granulomas. Several of these are important in Colombia and Latin America.
Step by step
- Organisms reach the liver by bile, portal blood, arterial blood or direct extension.
- Bacteria multiply in necrotic tissue; neutrophils liquefy it into an abscess.
- Amoebae lyse cells by contact; the cavity has little inflammation and trophozoites at the edge.
- Helminths provoke eosinophils, granulomas around eggs and fibrosis.
- Chronic biliary infestation causes hyperplasia, dysplasia and cholangiocarcinoma.
Non-viral infections of the liver
| Infection | Route | Lesion | Note |
|---|---|---|---|
| Pyogenic liver abscess | Biliary, portal, arterial, direct | Abscess with neutrophils and necrotic debris | Fever, pain, tender hepatomegaly; needs drainage if large |
| Amoebic liver abscess | Portal vein from colitis | Necrotic cavity, trophozoites at the rim | Often no current diarrhoea |
| Echinococcosis | Swallowed eggs from dog faeces | Hydatid cyst with laminated membrane and protoscolices | Calcified rim; anaphylaxis if ruptured |
| Schistosomiasis | Skin penetration in fresh water; eggs reach portal venules | Egg granulomas, pipe-stem periportal fibrosis | Portal hypertension with preserved function |
| Liver fluke infections | Raw fish (Clonorchis, Opisthorchis) or watercress (Fasciola) | Ductal hyperplasia, inflammation, fibrosis | Cholangiocarcinoma (Clonorchis, Opisthorchis) |
| Tuberculosis and histoplasmosis | Hematogenous | Epithelioid granulomas, caseating or not | Disseminated disease |
Test yourself
Think of the answer, then tap the question to see it.
What is the most common source of a pyogenic liver abscess?
Biliary tract disease with ascending cholangitis.
Where are trophozoites found in an amebic liver abscess?
At the edge of the necrotic cavity, next to viable tissue; the centre is acellular necrotic debris.
Why does schistosomiasis cause portal hypertension without liver failure?
Eggs trapped in portal venules cause periportal pipe-stem fibrosis, a presinusoidal block that spares the hepatocytes.
Which liver flukes raise the risk of cholangiocarcinoma?
Clonorchis sinensis and Opisthorchis species.
Connections
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Pyogenic liver abscess: MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2026); Amebic Liver Abscess (StatPearls (NCBI Bookshelf), 2025); Echinococcosis (World Health Organization, 2026).
Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake
Representative model, for educational purposes only.