- Echinococcus granulosus is a tapeworm that causes zoonotic infection (echinococcosis or hydatid disease), transferred to humans by ingestion of contaminated food with the parasite's eggs. Echinococcosis is endemic in southern Israel, especially in the Bedouin population. Humans, the intermediate hosts of the worm, develop cystic (larval) disease mainly of the liver or the lungs over long durations. Diagnosis requires a high index of suspicion, typical radiographic findings and specific serology test, which has low sensitivity in extra-hepatic cases. We report a 12 year old patient with fever, cough and chest pain, who was considered to have bacterial pneumonia with typical radiographic findings, and was treated with ceftriaxone and azithromycin. The patient did not recover as expected within a few days, and further investigation revealed evidence of hydatid cystic disease of her left lung, despite having negative serology for echinococcus. The patient fully recovered after surgical and albendazole treatment. We believe that hydatid disease should be suspected when a patient from an endemic area presents with fever and cough, supposedly representing as community acquired pneumonia, unresponsive to empiric antibiotic treatment. The radiographic findings should be carefully examined for typical findings, and negative serology for echinococcus does not rule out the diagnosis of hydatid cystic disease.