New Delhi: In a disturbing case of medical misdiagnosis, an 18-year-old boy was treated for tuberculosis (TB) for six months before doctors discovered that he was actually suffering from a parasitic lung infection, likely contracted from close contact with a stray dog.The patient experienced persistent coughing and fatigue—symptoms typically associated with TB. Based on his clinical presentation, he was put on a full course of anti-tuberculosis therapy. However, when his condition failed to improve, further diagnostic tests at CK Birla Hospital revealed the real cause: hydatid disease, a zoonotic infection caused by tapeworm Echinococcus granulosus.“This is not as uncommon as it sounds,” said Dr Vikas Mittal, director of pulmonology at CK Birla Hospital. “Zoonotic infections—those transmitted from animals to humans—can closely mimic common illnesses like TB. If clinicians don’t consider them, patients may be misdiagnosed and given unnecessary treatments.”Hydatid disease is spread through microscopic eggs found in the feces of infected dogs. These eggs can stick to the animal’s fur, soil or dust and can enter the human body through hand-to-mouth contact, if hands are not washed after petting or feeding stray dogs and cats. This can happen even with handling pets at home if they are not dewormed regularly.Once inside the body, the parasite can form cysts in vital organs such as the lungs, brain or liver, and cause pressure symptoms at the affected site. If the lungs are affected, it can cause respiratory distress, chest pain and general fatigue. These symptoms often mimic those of more common illnesses like TB, leading to misdiagnosis.According to experts, general physicians often diagnose tuberculosis solely on the basis of chest X-ray findings, without seeking specialist consultation or further investigation. This contributes significantly to misdiagnoses—especially in cases where radiological features overlap with other conditions.Dr Mittal said that in this case, the patient was suffering from a complicated, ruptured hydatid cyst in the lungs, which led to the accumulation of fluid in the chest cavity. He needed chest tube drainage to extract the fluid, a symptom that initially pointed towards TB. However, several indicators of a hydatid cyst were overlooked by the radiologist, possibly due to insufficient awareness, resulting in an incorrect diagnosis.Delhi and other Indian cities with large populations of free-roaming dogs are particularly vulnerable to such infections. Public health experts warn that while feeding or petting stray animals may seem harmless, it can carry serious health risks. “People think infections only come from bites, but many parasites don’t need bite to spread,” Dr Mittal pointed out. “Simple hygiene practices like hand washing can go a long way in preventing these infections.“Hydatid disease is listed as a neglected tropical disease by World Health Organization and is often underdiagnosed in resource-limited settings due to low awareness and limited access to advanced diagnostic tools.Experts advise people, particularly pet owners and those who regularly interact with strays, to inform their doctors about any animal exposure when reporting respiratory symptoms. In many cases, a simple additional test could prevent months of ineffective and potentially harmful treatment. They advise the public to avoid close contact with stray animals, maintain hygiene and seek a second opinion if common treatments fail to show results.
