Summary about Disease
Thelaziasis is a parasitic eye infection caused by nematode worms of the genus Thelazia. These worms live on the surface of the eye, in the conjunctival sac, and associated tissues of various mammals, including humans. The infection is generally not life-threatening but can cause significant discomfort and, in some cases, corneal damage.
Symptoms
Common symptoms of Thelaziasis include:
Eye irritation
Excessive tearing (lacrimation)
Conjunctivitis (redness and inflammation of the conjunctiva)
Foreign body sensation (feeling like something is in the eye)
Photophobia (sensitivity to light)
Pain
Blurred vision (in severe cases)
Corneal ulceration (rare)
Causes
Thelaziasis is caused by nematode worms of the genus Thelazia. The worms are transmitted by certain species of flies (intermediate hosts) that feed on the tears and ocular secretions of infected animals. The flies deposit larvae near the eyes, which then migrate into the conjunctival sac.
Medicine Used
The primary treatment for Thelaziasis involves the physical removal of the worms from the eye. Anesthetic eye drops may be used to numb the eye during this procedure. In some cases, medication may be used after manual extraction to ensure the infection is completely eradicated and prevent secondary bacterial infection.
Manual Removal: The most common and effective method.
Topical Antihelmintics: Ivermectin eye drops have been used effectively, but are not always available.
Antibiotic Eye Drops: Used to prevent secondary bacterial infections after worm removal.
Lubricating Eye Drops: To alleviate irritation and dryness.
Is Communicable
Thelaziasis is not directly communicable from person to person or from animal to person through casual contact. Transmission occurs indirectly through fly vectors. A fly has to feed on the tears of an infected individual (animal or human) and then transmit the Thelazia larvae to another individual's eye.
Precautions
Precautions to minimize the risk of Thelaziasis include:
Fly control measures (insecticides, fly traps).
Wearing glasses or protective eyewear in areas with high fly populations.
Good hygiene practices, including washing hands frequently.
Prompt treatment of infected animals.
Avoiding contact with the faces of animals that may carry the infection.
How long does an outbreak last?
The duration of an outbreak of Thelaziasis depends on factors such as fly populations, environmental conditions, and the number of infected hosts in an area. An outbreak can last for several weeks to months, typically corresponding with the active season of the specific fly vectors involved. A single infection in an individual can last until the worms are removed, which may be weeks to months if left untreated.
How is it diagnosed?
Diagnosis of Thelaziasis is typically made by a doctor or veterinarian through:
Visual Examination: Observing the worms moving on the surface of the eye.
Slit-Lamp Examination: A more detailed examination using a slit lamp to visualize the worms and any associated corneal damage.
Microscopic Examination: In some cases, a sample of ocular fluid may be examined microscopically to identify Thelazia larvae.
Timeline of Symptoms
The timeline of symptoms can vary, but typically follows this pattern:
Initial Infection: Exposure to Thelazia larvae deposited by flies.
Incubation Period: A short period (days to a week) before initial symptoms appear.
Early Symptoms: Eye irritation, excessive tearing, foreign body sensation.
Progressive Symptoms: Conjunctivitis, photophobia, pain.
Advanced Symptoms (if untreated): Blurred vision, corneal ulceration (rare).
Important Considerations
Thelaziasis can be misdiagnosed as other eye conditions, so it's important to consider the possibility of this infection in individuals presenting with consistent symptoms, especially if they live in or have traveled to areas where the infection is prevalent.
Prompt diagnosis and treatment are important to prevent complications.
Veterinarians and doctors should be aware of the distribution of Thelazia species in their region.
Public health efforts should focus on fly control and education about preventive measures.