The first positive serological study on rift valley fever in ruminants of Iran.

Background & objectives: Rift Valley fever (RVF) is a zoonotic vector-borne disease that primarily affects domestic animals but can also infect humans. The purpose of the present study was to investigate the presence of antibodies against RVF virus (RVFV) in ruminants, viz. cattle, sheep, and goats in Kurdistan Province of western Iran.

Methods: Blood samples were collected from 288 ruminants (118 cattle, 142 sheep and 28 goats) of both sexes, under age groups ≤1, 1-3, 3-5 and ≥5 yr, from January 2016 to December 2016. Clinical symptoms and history of abortion were recorded. The presence of RVFV-specific antibodies was investigated by using ELISA (competitive) and indirect immunofluorescence assay (IIFA) after separation of serum.

Results: The results of two tests were positive for five (1.74%) of total 288 animals which included two cattle of 118 (1.7%), and three sheep of 142 (2.11%). The results of IIFA were correlated with the ELISA results. All animals were clinically normal. No significant relationship between the RVFV infection rate and the variable considered, i.e. season, animal's age or sex, and the species of the animal (p ≥ 0.05), although there were four seropositive animals in the age group 1-3 and five seropositive animals in the spring season.

Interpretation & conclusion: The results of the study revealed the presence of low-level RVFV circulation among the ruminants of Kurdistan Province in Iran indicating that they are at risk of exposure to the virus during their lifetime. Since the present study was the first serological study on RVF in Iran with positive results, further studies are suggested including other areas of Iran.