[The relationship between mosquito vectors and aquatic birds in the potential transmission of 2 arboviruses].

The authors studied for two years the role of the chicks of aquatic birds in the arboviral cycles in coastal lagoons in central Panama in order to determine the relation between Culex (Melanoconion) ocossa and Mansonia (Mansonia) dyari mosquitoes in the transmission and dissemination of the viruses of Saint Louis Encephalitis (SLE) and Venezuelan Equine Encephalitis (VEE). Mosquitoes were captured every fifteen days on two consecutive nights to isolate the virus, using light traps (CDC) and baited traps. The attempts to isolate the virus were made using Vero cell cultures and the determination of antibodies was performed. The results of the serologic tests seem to indicate that four bird species: the ex (?) heron (Bubulcus ibis), the American heron (Casmerodius albus), the spoon-billed duck (Cochlearius cochlearius) and the needle crow (Anhinga anhinga) could function as intermediate hosts in the transmission cycle of SLE. Two species, the ibis (Endocimus albus) and the spoon-billed duck (Cochlearius cochlearius) could also be intermediate hosts of VEE in the coastal lagoons of Panama. The presence of antibodies in chicks could indicate an infection acquired recently, after their birth, in this area. The VEE virus was recovered from blood filled mosquitoes which had fed on a spoon-billed duck probably infected and exposed in a Trinidad #10 trap. No SLE virus was isolated. Other unknown viruses were isolated from mosquitoes selected for these studies, such as C. ocossa and M. dyari. The results obtained with these studies indicate the need for more studies utilizing new field techniques in order to establish a link between SLE and VEE, the vector mosquitoes and the aquatic birds in the coastal lagoons of the area under investigation.