Experience of establishing and coordinating a nationwide network for bidirectional intussusception surveillance in India: lessons for multisite research studies by Rakesh Kumar, Ashish Wakhlu, Manoja Kumar Das, Narendra Kumar Arora, Atul Gupta, John Mathai, Bhadresh R Vyas, Pavai Arunachalam, Cenita J Sam, Arindam Ray, Javeed Iqbal Bhat, Jayanta K Goswami, K Kameswari, Lalit Bharadia, Lalit Sankhe, Neelam Mohan, Pradeep K Jena, Rachita Sarangi, Rashmi Shad, Sanjib K Debbarma, J Shyamala, Simmi K Ratan, Suman Sarkar, Vijayendra Kumar, Anand P Dubey, Gowhar Nazir Mufti, Harsh Trivedi, Jimmy Shad, Kaushik Lahiri, Meera Luthra, P Padmalatha, Ruchirendu Sarkar, A Santosh Kumar, Subrat Kumar Sahoo, Sunil K Ghosh, Sushant Mane, Bashir Ahmad Charoo, Bikasha Bihary Tripathy, G Rajendra Prasad, S Harish Kumar, K Jothilakshmi, Nihar Ranjan Sarkar, Saurabh Garge, MK Ajaya Kumar, Satya SG Mohapatra