A truck driver has chronic cough with fever since one month. Chest x-ray show bilateral reticulonodular infiltrates in mid and lower zones. Which of the following is possible diagnosis?

Patients with Pneumocystis pneumonia develop dyspnoea,fever,and non productive cough.The classic findings on chest radiography consist of bilateral diffuse infiltrates beginning in the perihilar regions,but various atypical manifestations(nodular densities,cavitary lesions) have also been repoed.HRCT shows groundglass opacities in earlier stage. Reference:Harrison's medicine-18th edition,page no:1671.