Zoonotic arbovirus infections in cattle in Mozambique with special reference to Crimean-Congo hemorrhagic fever virus (CCHFV) and rift valley fever virus (RVFV).

BACKGROUND

Arboviruses pose a great threat to public health in sub-Saharan African countries. Mozambique is located in a region that is prone to climate change-related devastation, including heavy rainfalls and severe droughts that favor the emergence of zoonotic viruses transmitted by arthropods such as Crimean-Congo hemorrhagic fever virus (Orthonairovirus haemorrhagiae, CCHFV) and Rift Valley fever virus (Phlebovirus riftense, RVFV). Both viruses are closely associated with livestock farming, including cattle, and can cause symptoms of hemorrhagic fever in humans. Available previous data sets related to the presence of RVFV and especially CCHFV in Mozambique are rather scarce. Hence, the objective of this study was to evaluate the recent seroprevalence of both viruses in cattle in four localities of Limpopo National Park. In addition, ticks were collected and tested for the presence of different arboviruses.

METHODOLOGY

A total of 460 cattle blood samples were collected and analyzed for the presence of CCHFV and RVFV antibodies using ID Screen CCHF Double Antigen Multi-species (IgM/IgG) and ID Screen Rift Valley Fever Competition Multi-species commercial ELISA test kits (IDvet, Grabels, France), respectively. 1176 ticks were collected from the same animals and analyzed with different RT-qPCRs assays for CCHFV, Nairobi sheep disease virus (Orthonairovirus nairobiense, NSDV) virus and Dugbe virus (Orthonairovirus dugbeense, DUGV). Selected ticks were further screened by using a pan-Flavivirus melting curve PCR.

RESULTS

The overall seroprevalence was higher for CCHFV (50%) compared to RVFV (28%). While a significant difference in seroprevalence between age groups was only found for CCHFV, there was a difference in RVFV seroprevalence between sampling sites that was not observed for CCHFV. None of the viruses tested were found inside the ticks.

CONCLUSIONS

This study revealed the presence of anti-CCHFV and anti-RVFV antibodies in cattle from all four sampled localities suggesting that both viruses are circulating in cattle and may be an important cause of unidentified febrile illness in humans in the region.