Ishtiaq and her team have been investigating the effect of infectious diseases on the ecology and evolution of birds. Birds are susceptible to similar diseases as humans, but are not subject to the complexities of human socio-economic and cultural patterns. Thus they provide a better system to directly determine how ecological changes such as climate change, temperature, vector community, and habitat affect on the prevalence, and spread of disease. The current project examines the influence of altitudinal gradients on blood parasites in Himalayan birds. The extent to which the parasite diversity and transmission varies between migrant and non-migrant host species has not been adequately explored across an altitudinal gradient. Many migrants move between altitudes or to the plains, and thereby encounter different faunas of parasites and pathogens compared with resident species. In plains, the resident birds may act as reservoirs for blood parasites, increasing the risk of migrants to become infected with new parasites in wintering ground. Given that suitable vectors are present to transmit and maintain the infection, such migrants can form effective bridge for parasites between wintering and breeding grounds. Hence, increases the risk of infection to naive resident birds in high-altitude. The study aimed to explore the degree to which (a) migrant and resident avian hosts are infected with vector-borne parasites across altitudes in the western Himalayas, (b) expansion or contraction in geographical or altitudinal ranges of vector communities and consequent risks of parasite transmission in malaria-free zones. The western Himalayas are rich in species rich mountainous system where species turnover is associated with altitudinal variation in habitat, as well as temperature-dependent variation in species composition along the range (e.g. in mosquitoes). Thus provides an ideal system to explore temperature-dependent range expansion in vectors and their interaction with host-parasite system with changing climatic conditions. The project has many parallels with the human malaria model where increase in temperature in highland areas has led to increase in malaria cases. In addition, the resonance with the avian malaria model of the Hawaiian system where temperature threshold restrict the parasite transmission to mid-elevation forests. This multi-tiered host-parasite-vector system has important world-wide implications for deriving general predictions relating to climate change. It is important to undertake such basic studies of disease transmission, vector populations to understand the general conditions that promote host switching and the emergence of novel pathogens.