The sudden onset of a sore throat after a traditional meal can easily be dismissed as an allergy, a cold, or irritation. In rare cases, however, it may signal Halzoun syndrome, a parasitic infection associated with eating raw or undercooked infected liver. For Lebanon, where raw sheep or goat liver is part of local food culture in some communities, documenting these occurrences raises awareness and helps to prevent misdiagnosis.  

This is the focus of the study “Halzoun syndrome in Lebanon: Clinical and genetic insights into Dicrocoelium dendriticum,” published in Tropical Medicine & International Health. Led by Dr. Charbel Al Khoury, assistant professor of microbial genomics at the School of Arts and Sciences, along with LAU students, the study investigates newly detected cases of Halzoun syndrome in North Bekaa.

The team sought to identify the parasite behind the symptoms and understand whether the Lebanese isolate was genetically related to known Dicrocoelium species, parasitic flatworms, or flukes, common in cattle or grazing animals. The researchers’ method combined field reporting, patient interviews, liver examination, and genetic testing. Five local butcheries helped to report suspected illness after raw liver consumption and preserved leftover liver samples for analysis.

From May 2024 to January 2025, the network identified four cases in one family, all in late June 2024. After requesting each patient to complete a 25-question interview, examining the suspected goat liver in the lab, and recovering 12 parasites for further study, the researchers compared the Lebanese sequence with 108 Dicrocoelium sequences from public databases. 

Four patients became clinically ill within hours of eating the same goat liver. They developed symptoms typical of Halzoun syndrome, including severe throat inflammation, throat itching, nasal congestion or discharge, vomiting, coughing and sneezing.

One 43-year-old man had a severe reaction, including tearing, difficulty breathing, and headache, which required corticosteroids and oxygen therapy. The absence of abdominal pain, chronic diarrhea, and expelled motile worms helped support the diagnosis and distinguish it from related conditions.

The liver analysis provided another clue. The sample revealed pale nodules, calcified nodules, thickening around the bile ducts, and localized discoloration, all of which were consistent with inflammation linked to flukes or their eggs. 

According to Dr. Al Khoury, obtaining reliable source material after the suspected exposure was one of the major challenges. In most cases, the food item is not available for analysis by the time symptoms appear. However, in this particular case, recovering the remaining goat liver from the butchery in question allowed the team to examine the tissue, extract parasites from the liver lesions, and proceed with molecular identification. 

This was especially important because Halzoun syndrome can be difficult to confirm clinically. Dr. Al Khoury explained that the parasite is not always recovered directly from patients, symptoms can resemble allergic or upper respiratory reactions, and the parasite may only be briefly present in the nasopharyngeal region. For that reason, the study relied on the suspected liver source as the key biological material for parasitological and molecular investigation. 

DNA testing confirmed that Dicrocoelium dendriticum, a liver fluke, was most likely responsible for the four cases.

The researchers also found that the parasite from Lebanon was not identical to other known samples of the same species. When they compared its DNA with samples from other countries, the Lebanese parasite appeared to belong to D. dendriticum, but it stood slightly apart from the main group.

Still, Dr. Al Khoury cautioned against drawing clinical conclusions too quickly. Although the study detected notable genetic divergence and a distinct haplotype pattern, suggesting that the Lebanese D. dendriticum isolate may represent a locally divergent lineage, linking this difference to disease severity would require more cases, broader sampling across Lebanon, and additional biological experiments. 

“At this stage, we do not have evidence that the genetically divergent Lebanese isolate causes a more severe or less severe form of the disease,” he said.

With only four cases from the same family, he added, it would not be scientifically valid to attribute that severity to the parasite’s genetic profile. Other factors, such as immune response, exposure level, parasite burden, and patient-specific differences, may also affect clinical outcome. 

For consumers, “avoiding raw liver remains the most effective way to prevent Halzoun syndrome, especially in regions where the consumption of raw sheep or goat liver is culturally practiced,” said Dr. Al Khoury.

Other more practical steps are cooking liver thoroughly, buying it and meat products from trusted sources where animals undergo proper veterinary inspection, avoiding liver that appears abnormal, nodular, discolored or visibly damaged, and maintaining proper food hygiene to prevent cross-contamination between raw liver and ready-to-eat foods. 

“It is important to emphasize, however, that visual inspection alone is not sufficient to guarantee safety,” warned Dr. Al Khoury. In this study, the implicated goat liver showed nodular lesions and evidence of parasitic infection, but not all contaminated tissue will necessarily be easy for consumers to recognize. 

Halzoun syndrome remains rare and easily misdiagnosed, but this study shows why local surveillance matters. Better awareness, safer handling of raw liver, and further genetic work could help clinicians and public health teams recognize the condition in the early stages and determine whether Lebanon’s parasite population carries distinct local features. 

To browse more scholarly output by the LAU community, visit our open-access digital archive, the Lebanese American University Repository (LAUR).