Tropical pulmonary eosinophilia is a term that was first coined by Weingarten in 1943. It was used to describe a condition that caused fever, wheezing, eosinophilia along with bilateral mottling of the lungs. Pulmonary esosinophilia was thought to be a self-limiting condition. However, it is accepted that it can cause scarring of lung tissue, and is not a fatal condition.
Pulmonary eosinophilia is common in regions with filarial endemicity. These regions include the Indian subcontinent, South East Asia, South America and Africa. The condition can occur in about less than 1% of filarial infections. It occurs only as a hypersensitivity reaction to the microfilariae of Wuchereriabancroftiand Brugiamalayi.
Tropical pulmonary eosinophilia is a rare condition. The correct diagnosis can be delayed for up to 5 years due to the chronic symptoms. Thus, it is very important to diagnose the condition as early as possible to prevent interstitial fibrosis and the subsequent irreversible damage to the lung tissue.
Pulmonary eosinophilia commonly occurs in young males than females. It is usually seen affecting the age group of 15 to 40 years. The symptoms may involve different body systems, but usually affects the lungs. The respiratory symptoms of tropical pulmonary eosinophilia include:
- Persistent, aggravated cough
- Chest pain
- The sputum may be scanty, but is mucoid and viscous
The symptoms are often nocturnal. The vigorous coughing may lead to rib fractures and chest pain.
Other symptoms of pulmonary eosinophilia include:
- Weight loss
- Enlarged lymph nodes in the neck
- Enlarged spleen
- Asthamatic attacks
Pulmonary eosinophila is caused by Wuchereriabancrofti. It is a human parasitic roundworm that leads to lymphatic filariasis. They spread by a mosquito vector. Other worms that can lead to lymphatic filariasis include Brugiamalayi and Brugiatimori. However, W. bancroftiis the most common and prevalent common the three. Humans are their definitive hosts and mosquitoes serve as their intermediate hosts.
The adult parasites reside in the lymphatic system of their human host. They are often found in the lymph glands of the lower part of the body. Their first stage larvae called the microfilariae are present in the blood. Most of the symptoms are due to the hypersensitivity reaction of the immune system to these microfilariae.
Diagnosis is based on the patient medical history that supports exposure to lymphatic filariasis. Serological tests, stool examination, or clinical response to anthelmintic medication (diethylcarbamzine) helps determine pulmonary eosinophilia. A blood smear taken during the ‘period’ that is the time when the microfilariae are present in the peripheral blood, helps distinguish the causative parasite from other potential parasites. A Polymerase chain reaction also helps determine filarial DNA. USG may help find movements and noises of the adult worms. X-rays can be useful in detecting dead, calcified worms.
There is no specific treatment for tropical pulmonary eosinophilia. The patient is given diethylcarbamazine in 3 doses for 21 days. The eosinophil count usually drops after 7 to 10 days of treatment.
Pulmonary eosinophilia is often confused with tuberculosis or asthma. Correct diagnosis is very important to reduce the chances of developing lung scar tissue. If one lives in a region known for filarial infection or has travelled to such a region, they should be considered for W. bancroftiinfection for early diagnosis.
Written by: Saptakee sengupta
Date last updated: April 07, 2015