Detection of serum neutralizing antibodies to Simbu sero-group viruses in cattle in Tanzania.

BACKGROUND: Orthobunyaviruses belonging to the Simbu sero-group occur worldwide, including the newly recognized Schmallenberg virus (SBV) in Europe. These viruses cause congenital malformations and reproductive losses in ruminants. Information on the presence of these viruses in Africa is scarce and the origin of SBV is unknown. The aim of this study was to investigate the presence of antibodies against SBV and closely related viruses in cattle in Tanzania, and their possible association with reproductive disorders. RESULTS: In a cross-sectional study, serum from 659 cattle from 202 herds collected in 2012/2013 were analyzed using a commercial kit for SBV ELISA, and 61 % were positive. Univariable logistic regression revealed significant association between ELISA seropositivity and reproductive disorders (OR = 1.9). Sera from the same area collected in 2008/2009, before the SBV epidemic in Europe, were also tested and 71 (54.6 %) of 130 were positive. To interpret the ELISA results, SBV virus neutralization test (VNT) was performed on 110 sera collected in 2012/2013, of which 51 % were positive. Of 71 sera from 2008/2009, 21 % were positive. To investigate potential cross reactivity with related viruses, 45 sera from 2012/2013 that were positive in SBV ELISA were analyzed in VNTs for Aino, Akabane, Douglas, Peaton, Sabo, SBV, Sathuperi, Shamonda, Simbu and Tinaroo viruses. All 45 sera were positive for one or more of these viruses. Twenty-nine sera (64.4 %) were positive for SBV, and one had the highest titer for this virus. CONCLUSIONS: This is the first indication that Aino, Akabane, Douglas, Peaton, Sabo, SBV, Sathuperi, Shamonda and Tinaroo viruses circulate and cause negative effect on reproductive performance in cattle in Tanzania. SBV or a closely related virus was present before the European epidemic. However, potential cross reactivity complicates the interpretation of serological studies in areas where several related viruses may circulate. Virus isolation and molecular characterization in cattle and/or vectors is recommended to further identify the viruses circulating in this region. However, isolation in cattle is difficult due to short viremic period of 2 to 6 days, and isolation in vectors does not necessarily reflect the situation in cattle.

First isolation, identification, phenotypic and genotypic characterization of Brucella abortus biovar 3 from dairy cattle in Tanzania.

BACKGROUND: Brucellosis is a disease of worldwide public health and economic importance. Successful control is based on knowledge of epidemiology and strains present in an area. In developing countries, most investigations are based on serological assays. This study aimed at investigating a dairy herd experiencing abortions in order to establish within-herd seroprevalence to Brucella spp., identify, characterize Brucella strains by Multiple Loci Variable Number of Tandem Repeats Analysis (MLVA-VNTR) and investigate possible spillover to other species. RESULTS: The within-herd seroprevalence in cattle (n = 200) was 48 % (95 % CI 41-55), using an indirect ELISA, while the Rose Bengal Test (RBT) yielded lower prevalence (21.5 %; 95 % CI 16-27). Two sheep (n = 35) and one goat (n = 50) were seropositive using ELISA while none of the dogs (n = 6) was positive with the RBT. Three Brucella were isolated from an aborted fetus and associated membranes. Real time PCR (IS711), Bruce-ladder and classical biotyping classified the isolates as B. abortus biovar 3. MLVA-VNTR revealed two different but closely related genotypes. The isolates showed unique profiles, providing the first genotypic data from Tanzania. These genotypes were not related to B. abortus biovar 3 reference strain Tulya originally isolated from a human patient in Uganda in 1958, unlike the genotypes isolated and characterized recently in Kenya. High within-herd prevalence, isolation of the pathogen and abortion confirm that B. abortus is circulating in this herd with cattle as reservoir hosts. A low seroprevalence in sheep and goats suggests a spillover of B. abortus from cattle to small ruminants in the herd. CONCLUSIONS: This is the first isolation and characterization of B. abortus biovar 3 from a dairy cow with abortion in Tanzania. The origin of the Tanzanian genotypes remain elusive, although they seem to be related to genotypes found in Europe, Turkey and China but not related to B. abortus biovar 3 reference strain or genotypes from Kenya. Importantly, replacement heifers are commonly sourced from large farms like this to smallholder farmers, which poses risk of spread of bacteria to other herds. B. abortus is a significant zoonotic risk and animal health problem in this production system, therefore further studies on humans is recommended.

Cross-border transport of rescue dogs may spread rabies in Europe.

Harmonisation of regulations in the European Union and the European Economic Area, as of January 1, 2012, has led to an increase in the number of rescue dogs imported to Norway from Eastern European countries, in particular Romania. Today the only requirements for dogs entering Norway are rabies vaccination and prophylactic Echinococcus multilocularis treatment. The aim of this study was to investigate the antibody levels to rabies virus in vaccinated rescue dogs and to examine if the dogs had sufficient antibody response according to the recommended titre ≥0.5 IU/ml by the World Organisation for Animal Health (OIE). A significant proportion (53%, 95% CI (41% to 65%)) of imported rescue dogs from Eastern Europe were found to have inadequate titres after rabies vaccination. Moreover, 41 per cent of the dogs had antibody levels below or equal to 0.2 IU/ml, and among these, 14 dogs had titres ≤0.1 IU/ml, which is considered negative in the fluorescent antibody virus neutralisation assay. This study indicates that the present regulation increases the risk of introducing rabies from member states where rabies is still prevalent to countries considered free from rabies.

The prevalence and spatial clustering of Neospora caninum in dairy herds in Norway.

The aims of this study were to estimate the national herd prevalence and the general spatial distribution of Neospora caninum infection in Norwegian dairy cattle. Bulk milk samples from 1657 randomly selected dairy herds were analysed by iscom ELISA for the presence of N. caninum specific antibodies. The national herd prevalence was estimated to be 0.7% (95% CI: 0.3-1.2%), which is the lowest national herd prevalence reported in Europe. In addition, we included a subpopulation study in which all 400 herds in the Oslo, Akershus and Østfold counties were sampled, and we found a herd prevalence of 1.8%. In the national herd study, a significant cluster of N. caninum infected herds was identified in Jaeren, on the south west coast of Norway. Jaeren has the highest density of farm animals in the country as well as climatic conditions that favour parasite survival. Dairy herds in this region had a 52 times higher relative risk of being N. caninum positive than dairy herds in other parts of Norway. This indicates that even though N. caninum infection is of minor importance in Norway, infection might cause abortion problems in high risk areas.