Serological response of cattle vaccinated with a bivalent (SAT 1 and SAT 2) foot-and-mouth disease vaccine in Gaza Province, Mozambique

Foot-and-mouth disease (FMD) is a viral disease endemic in Africa, the Middle East, South America, Asia and parts of Eastern Europe. It is a major constraint to international trade in livestock and livestock products in many African countries. In southern Africa, African buffaloes (Syncerus caffer) are reservoirs of the South African Territories (SAT) 1, SAT 2 and SAT 3 FMD viruses, and cattle raised in the vicinity of wildlife conservation areas are at constant risk of becoming infected with FMD viruses. In Mozambique, control of FMD is fundamentally based on vaccination of cattle in zones around protected areas. However, the vaccination protocol recommended by the vaccine producer (two primary vaccinations followed by four- to six-monthly boosters) is logistically impractical and financially not suitable for most countries. As a result, the double primary vaccination is usually not implemented. A commercially available bivalent FMD vaccine, containing the SAT 1 and SAT 2 serotypes, was assessed for its ability to induce and sustain immunity in cattle for at least 6 months following a single primary inoculation. The study was conducted with cattle reared in Limpopo National Park (LNP), Mozambique, and adjacent areas. One hundred and seventy five seronegative cattle aged between 6 and 18 months were vaccinated and 42 others from the same areas were left unvaccinated, as controls. A group of 39 vaccinated cattle were revaccinated 4 months after initial vaccination and 63 others were revaccinated 6 months after initial vaccination. The vaccinated and unvaccinated cattle were bled at predefined intervals (at vaccination, and at 1, 4, 5, 6, 8, 10 and 12 months post vaccination) and sera were tested with a liquid phase blocking ELISA to measure the antibody level against FMD virus. A high proportion (73%) of vaccinated cattle had seroconverted (log10 titre ≥1.6 for any SAT serotype) at one month after vaccination with a single primary dose and there was no significant difference between the proportions of animals that seroconverted to SAT 1 compared to SAT 2. A higher proportion of animals within LNP (82%) than outside LNP (50%) had seroconverted at one month after vaccination (P = 0.001). Overall, however, only relatively few animals (27% for SAT 1, 35% for SAT 2 and 7% for SAT 3) had protective antibody titres (log10 titre ≥2). At 4 months after vaccination, a very low proportion (8.3%) of vaccinated cattle had antibody titres ≥1.6 to any of the SAT serotypes, and there was no significant difference between the proportions of animals with antibodies to SAT 1 (2.1%) compared to SAT 2 (7.3%) (P = 0.17). No cattle had a protective titre (≥2) to SAT 1 at 4 months and only 4.2% to SAT 2. The revaccination at 4 months after initial vaccination elicited antibody titres ≥1.6 in 22% of vaccinated animals at one month after revaccination; this rose two months later to 90% and remained high (91%) at 10 months post first vaccination before dropping to 65% at 12 months. However, only 15% of cattle had protective titres (≥2) to any of the SAT serotypes at 12 months. For cattle revaccinated at 6 months after first vaccination the percentage of cattle that had a titre ≥1.6 two months after revaccination was also high (80%), remained high (89%) at 10 months post first vaccination and dropped to 54% at 12 months after first vaccination. Only 11% of cattle had protective titres (≥2) at 12 months. The research findings indicate that, although the vaccine is able to induce production of antibodies against SAT 1 and 2 in a significant percentage of cattle within one month after a single primary vaccination, these antibodies are short lived and have largely disappeared by 4 months post vaccination. This suggests that a protocol of a single primary vaccination is inadequate in naïve animals, even if revaccination takes place four months later. Revaccination improved the immune response for a longer period, resulting in detectible titres in the majority of animals for 6-8 months post revaccination. This can be used in disease control programmes to ensure some protection of cattle particularly when it is applied immediately before identified high risk periods of occurrence of FMD outbreaks. However, it seems unlikely that six-monthly revaccination is sufficient to maintain adequate levels of protective immunity. The study highlighted several difficulties associated with the vaccination of livestock under field conditions and the conduction of field trials. These included difficulties with cold chain maintenance, poor infrastructure for animal handling, and loss of follow-up due to loss of animal identification or poor owner/herder compliance. CopyrightDissertation (MSc)--University of Pretoria, 2012.Production Animal Studiesunrestricte

Bovine tuberculosis and brucellosis in cattle and African buffalo in the Limpopo National Park, Mozambique

Bovine tuberculosis (BTB) and brucellosis are prevalent in buffaloes of the Kruger National Park (KNP, South Africa). Both diseases were considered to have no or a very low prevalence in wildlife and livestock in and around the Limpopo National Park (LNP, Mozambique). The same applies for tuberculosis in Gonarezhou National Park (GNP, Zimbabwe), but just recently, BTB was detected in buffaloes in the GNP and fears arose that the disease might also spread to the LNP as a result of the partial removal of the fences between the three parks to form the Great Limpopo Transfrontier Park. To assess the status of both diseases in and around LNP, 62 buffaloes were tested for bovine tuberculosis (BTB) and bovine brucellosis. The percentage of positive BTB reactors in buffalo was 8.06% using BovidTB Stat-Pak and 0% with BOVIGAM IFN-c test and IDEXX ELISA. The brucellosis seroprevalence in buffalo was found to be 17.72% and 27.42% using Rose Bengal Test (RBT) and ELISA, respectively. In addition, 2445 cattle in and around the LNP were examined for BTB using the single intradermal cervical comparative tuberculin test (SICCT), and an apparent prevalence of 0.98% was found with no significant difference inside (0.5%) and outside (1.3%) the park. This is the first published report on the presence of positive reactors to BTB and bovine brucellosis in buffalo and cattle in and outside the LNP. Monitoring the wildlife–livestock–human interface of zoonotic high-impact diseases such as BTB and brucellosis is of outmost importance for the successful implementation and management of any transfrontier park that aims to improve the livelihoods of the local communities.German Research Foundation (DFG).http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1865-16822016-12-31hb2016Veterinary Tropical Disease

H7N6 highly pathogenic avian influenza in Mozambique, 2023

ABSTRACTOn 13 October 2023, the National Directorate for Livestock Development in Mozambique was notified of a suspected outbreak of avian influenza in commercial layers. Samples were screened by real-time and conventional RT–PCR and were positive for both H7 and N6. Full genome sequences were obtained for three representative samples. Sequence analysis of the H7 cleavage site confirmed that the viruses were highly pathogenic (i.e. 333- PEPPKGPRFRR/GLF-346). In addition, the H7 and N6 sequences were highly similar (from 99.4-99.5% and 99.6-99.7% for the HA gene and the NA gene, respectively) to the sequences of a H7N6 virus identified in the Republic of South Africa in May 2023 indicating a similar origin of the viruses. The identification of H7N6 HPAIV in Mozambique has important implications for disease management and food security in the region

H7N6 highly pathogenic avian influenza in Mozambique, 2023

On 13 October 2023, the National Directorate for Livestock Development in Mozambique was notified of a suspected outbreak of avian influenza in commercial layers. Samples were screened by real-time and conventional RT–PCR and were positive for both H7 and N6. Full genome sequences were obtained for three representative samples. Sequence analysis of the H7 cleavage site confirmed that the viruses were highly pathogenic (i.e. 333- PEPPKGPRFRR/GLF-346). In addition, the H7 and N6 sequences were highly similar (from 99.4-99.5% and 99.6-99.7% for the HA gene and the NA gene, respectively) to the sequences of a H7N6 virus identified in the Republic of South Africa in May 2023 indicating a similar origin of the viruses. The identification of H7N6 HPAIV in Mozambique has important implications for disease management and food security in the region.</p