Most patients become infected with E. granulosus in childhood [7] , as children are in an intimate contact with infected animals at play [5] [7] [15] . The cyst grows very slowly, so symptoms may not appear and the disease may not be diagnosed until many years later [7] . Five to twenty years may elapse before the cysts enlarge sufficiently to cause symptoms [2] . Hydatid disease is seen in subjects of any age and sex, although it is more common in those aged 20 - 40 yrs [16] . Sixty percent of our patients were in the second and third decades; this finding was similarly reported by Sarsam [8] . The youngest patient with PHD was one year old reported by Kavukcu et al. [17] . Our youngest patient was two and a half years old.

Fifty seven percent of our patients were females. Al-Mukhtar, from Iraq [18] and Yaghan et al. from Jordan [19] got a similar finding. A higher prevalence among females has also been reported in some other communities such as East Africa and Ethiopia [19] . In contrast, some authors reported slightly higher prevalence among males [17] [20] . “Women in rural areas are closely associated with domestic and farm duties, such as milking animals and cultivating crops while most men are military or government personnel” [19] . Moreover, Rokni [4] and Yaghan et al. [19] blame geophagia in poor children and pregnant women to be another source of infection.

^*The z-Score is 4.1219. The p-value is 0. The result is significant at p < 0.05.

^*One cyst was explored but not removed as it was adherent to the arch of the aorta simulating an aneurysm. The patient had no preoperative aortography to clarify the diagnosis.

^*Two patients with prolonged air leak as well as two patients with postoperative bleeding were managed surgically whereas others were managed conservatively.

Forty five percent (n = 30) of our patients were housewives. The rate was even higher in studies from Iran [4] in which housewives had the highest rate of infection (51.3% - 75%). “Housewives, especially in rural areas, where the most infected cases can be found, have the highest chance of contact with the sources of infection. Contact with contaminated vegetables, cleaning the house containing the dog faeces, and desire to eat soil (geophagy) as longing in pregnancy embrace the etiological issues” [4] .

The symptoms depend on size and site of the lesion. Slowly growing echinococcal cysts generally remain asymptomatic until their expanding size and their space occupying effect in the lung elicits symptoms [2] . The common symptoms in our study as well as in other studies were cough, chest pain and breathlessness [1] - [4] [6] [13] [17] . There are many case reports of chronic cough and progressive dyspnoea due to PHC misdiagnosed as bronchial asthma [1] [15] . Therefore, physicians working in endemic areas or treating patients from endemic areas should be aware of hydatid disease [1] [19] . “It is important to remember that HC may have very unusual presentations” [19] . Haemoptysis is associated with both simple and complicated cysts, although it is more common in the latter [8] . High fever characterizes the onset of infection or rupture of a cyst [5] [6] [15] . Symptoms of intoxication are common in suppurative cysts with fetid contents [6] [7] [15] . In the present study, 15 patients were acutely ill. Three of our patients had expectoration of grape skin-like material that was pathognomonic of intra-bronchial rupture of PHC [15] while two had tension pneumothorax due to the rare intra-pleural HC rupture [1] [9] [11] . Hoarseness of voice was observed once due to a big HC compressing the left recurrent laryngeal nerve. Anorexia and weight loss each observed in 3 patients were most likely related to low economic class of most patients particularly those living in rural areas (77%). Inadvertent aspiration of hydatid fluid was diagnostic in one case.

The diagnosis is based on 1) history and geography, 2) imaging, 3) serology [21] and 4) bronchoscopy. Routine haematological and biochemical tests do not help in the diagnosis of hydatid disease [2] .

Hydatid disease is a dynamic entity with varying imaging appearances. Familiarity with imaging findings, especially in patients living in countries where this disease is endemic, provides important advantages in making the diagnosis. Hydatid cyst should be kept in mind when a cystic lesion is encountered anywhere in the body [22] .

Plain chest radiography is the main diagnostic tool. Plain films will usually define the pulmonary cysts as rounded, irregular masses of uniform density, but they may miss the cysts in other organs [2] .

PHCs may vary from 1 to 20 cm in diameter. Because of their compressibility, the lungs are the only organ in which HCs can grow so large. The high prevalence of PHCs in childhood can also be attributed for this feature [22] .

There are 3 radiologic signs considered diagnostic of ruptured pulmonary hydatid cyst (PHC): perivesicular pneumocyst, double-domed arch, and water lily. Apart from these, every localized radiologic density seen in any patient more than 3 years of age in an endemic area should be looked on as a possible ruptured hydatid cyst [12] .

In our study, plain chest radiography was the main diagnostic tool. None of the patients required a CT scan of the chest; however, CT scan was sometimes necessary in cases of complicated hydatid cysts or suspicion of tumours.

Bronchoscopy is unnecessary in cases of ruptured PHC with a pathognomonic clinical picture, radiologic picture, or both [12] . However, it is indispensable when there is suspicion of tumor or when the radiologic picture is atypical. The source of hemoptysis (if present) can be traced [12] . The finding of laminated membrane in a bronchus draining the cyst cavity (be it lobar, segmental, or subsegmental) is diagnostic. A piece of the membrane can be obtained and examined with a hand lens or microscopically to confirm its laminated nature. The bronchial aspirate can be examined for the presence of hooklets [12] .

In a huge intact PHC, bronchoscopy is hazardous as it can induce rupture of the cyst due to the effect of cough that usually follows bronchoscopy; moreover, the findings are usually not conclusive (mucosal erythema, external compression or normal bronchoscopy).

In patients with pulmonary opacities simulating tumours, bronchoscopy is necessary for diagnosis.

In our study, bronchoscopy was part of the diagnostic work-up of 4 patients only. All of them had haemoptysis and suspicion of tumour. It was diagnostic in a case of middle lobe HC by seeing a laminated membrane protruding through the offended bronchus.

Although Das et al. from India had diagnosed a PHC and mediastinal HC by ultrasound-guided fine needle aspiration cytology [23] , we believe that such a maneuver should not be attempted whenever there is suspicion of PHC as it causes cyst rupture with its dangerous sequels.

The aim of surgery in pulmonary hydatid cyst is to remove the cyst completely while preserving the lung tissue as much as possible. Lung resection is performed only if there is an irreversible and disseminated pulmonary destruction [24] . Lung preserving surgery was done in 76 cysts (91.5%) while lobectomy was necessary in 7.

There are two methods for management of the residual cyst cavity: capitonnage that is closure of the cavity after removing its contents with a series of purse string sutures starting from the bottom outwards and cystotomy and closure of bronchial orifices leaving the cavity open [10] . Which option is better? This is a very controversial issue [10] . We share many authors their opinion that capitonnage is unnecessary [8] [10] [13] ; we used it in only 16 of our cases (19.2%). Sarcasm [8] and Elhassani [6] recommended leaving the residual sac open to obliterate spontaneously after closure of bronchial fistulae and emphasized that no attempt should be made to suture it. Moreover, Sarsam believed that obliteration of the cavities of multiple cysts, particularly when large, may convert the remaining lung tissue into a collapsed and distorted mass, prone to infection and other complications [8] . Shehatha et al. (2008) studied 763 cases of thoracic hydatidosis managed by leaving all the cavities open and obtained good results [13] . In contrast, Al-Ali and Baram claimed that low complication rate was achieved following capitonnage in 72 cases of PHC [cited in 10].The study, however, had several limitations particularly the lack of a control group and deficient follow-up [10] .

Not infrequently, thoracic surgeons are asked for the management of hydatid cysts located at the upper part (subdiaphragmatic location) of the liver. A thoracotomy provides better exploration and access to the cyst located in this area when compared to laparotomy [24] . Four patients were managed by this approach in our study.

In this study, we observed that complications such as prolonged air leak, wound infection, empyema, atelectasis and bleeding seemed to be higher following surgery for ruptured than intact cysts. However, only empyema was statistically significant. Ruptured cysts are usually already infected and this may explain this finding.

Regarding complications vs. type of surgery (lung preservation or resection), apparently they were fewer after resection. However, the differences were not statistically significant except for bleeding which was higher after resection (This may be due to small sample size).

There is a general agreement about the central role of surgery in management of pulmonary hydatidosis and the adjuvant value of medical therapy [13] . Percutaneous aspiration has not been accepted or reported as a therapeutic option for pulmonary hydatidosis in Iraq, however, thoracoscopic removal of few PHCs has been reported once [14] .