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Sometimes, patients walk in saying, “I have eosinophilia,” or describe a friend or relative who has the complaint. It is difficult to understand what they mean. Do they have wheezing? Or has a blood test revealed a high eosinophil count?
Wheezing is a high-pitched whistling sound — with or without chest tightening and discomfort. The sound occurs because the airways in the lung contract so that air is forced out through a narrowed opening. Blowing air into a balloon and then holding its mouth partially open can produce a similar effect. Wheezing occurs for a variety of reasons, such as exposure to inhaled or ingested allergens or viral and bacterial infections. It can also occur when the eosinophil content of the blood increases.
Wheezing is equated with asthma — a frightening word. It conjures up visions of an emaciated, permanently incapacitated individual, with breathlessness and a hacking cough. Incidentally, asthma is a term that is not in use any more as the illness has been renamed “reactive airways disease”. People, however, prefer to use eosinophilia in conversation as it is a safe, non-life threatening, benign medical diagnosis to describe all kinds of wheezing.
Human blood contains four types of white blood cells (WBCs) — neutrophils, lymphocytes, monocytes and eosinophils. The percentage of eosinophils is usually less than 6 per cent. The total count of eosinophils in 1ml is 500 or less. If the count is greater than this, it is diagnosed as eosinophilia. If the count is 1500 or more then hyper eosinophilia is diagnosed. This is a laboratory diagnosis made after analysing a blood smear.
Eosinophils are useful cells, which destroy foreign substances (bacteria, viruses, parasites, tumour cells) marked as dangerous by the immune system. This action of the eosinophils can release chemicals such as histamine, which cause inflammation and can result in wheezing.
The eosinophil count can rise for a variety of reasons:
• Parasitic infection particularly filaria, hook worm, round worm and pin worm.
• Fungal diseases of the skin
• Allergy to inhaled compounds, food like seafish or prawns, food colouring (red and yellow) or additives (monosodium glutamate) and even medication.
• Eczematous skin lesions that are itchy and weepy
• Endocrine disorders
• Tumours like ovarian cancer
• Blood cancers such as some types of leukaemia and lymphoma
• Autoimmune diseases such as ulcerative colitis
A high eosinophil count with wheezing can occur in a condition called Tropical Pulmonary Eosinophilia (TPE). It is peculiar to Southeast Asia and India. It occurs because that particular person has an abnormally vigorous immunological response to the parasites Wuchereria bancrofti and Brugia malayi, which cause filaria.
Filaria is endemic in India. The filaria parasite is injected into the blood through the bite of an infected mosquito. The victim develops typical filaria with fever, swelling of the limbs and enlarged lymph nodes. The parasite breeds in the lymph nodes and more and more worms are released into the blood stream. Blood vessels in the lung attempt to get rid of these parasites with the help of eosinophils. Some patients react vigorously to the infection, producing a large number of eosinophils. The eosinophil count in the blood rises. Meanwhile, some worms get trapped, die and release allergenic chemicals, precipitating wheezing and coughing.
TPE is suspected in patients with a cough, breathlessness and wheezing, which often worsens at night. There may also be fever, loss of appetite and weight loss. Pulmonary function tests show restrictive and obstructive defects. The chest X-ray shows typical changes. Blood tests show a high eosinophil count. The diagnosis is clinched with the demonstration of high serum concentrations of filarial specific antibodies.
Although TPE was considered a disease of Asia, increased travel has spread it all over the world. Fortunately, it is an eminently treatable condition. Most patients respond well to a 21-day course of diethylcarbamazine citrate, an inexpensive tablet marketed by a number of drug companies. Mild wheezing may, however, persist for longer in a few people.
In any case of wheezing, avoid inhaled allergens such as mosquito repellents (coils, mats, liquid or spray). While waiting for a diagnosis, take steam inhalations morning and evening. Medication is usually prescribed as an inhaler or rotahalor, which will deliver medicine directly to the lungs, produce no side effects and keep you comfortable. Treatment can be initiated after a specific diagnosis is made.
Wheezing is just a symptom. All wheezing is not asthma nor is it eosinophilia. It is important to obtain an accurate diagnosis to determine the reason behind it. Specific treatment will provide a cure once the diagnosis is made.
Dr Gita Mathai is a paediatrician with a family practice at Vellore. Questions on health issues may be emailed to her at yourhealthgm@yahoo.co.in
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