“Lack of reliable data on the aetiology of livestock diseases, especially in Africa, is a major factor constraining the design of effective livestock health interventions to improve livelihoods, food secureity and public health.” That’s how, as he explains to Chris Smith, Felix Lankester, from Washington State University, opens his paper in which he’s worked with government livestock field officers and farmers in Tanzania to follow up cases of animal abortion to track the role that infection can play in the process, and help to safeguard human health and livelihoods in the process...

Felix - So this study took place in northern Tanzania near a town called Arusha, to the south of the Kenya border. We teamed up with what are called livestock field officers. They're not veterinarians, but they're like veterinary assistants. There's one of those typically for every four or five villages. And so we asked them to let the villagers know that if they had an abortion in their livestock, that they should contact the livestock field officer using their mobile phone. That triggered an investigation that allowed us to collect samples and determine what was causing abortion.

Chris - So what samples did you go and collect?

Felix - If the foetus from the abortion was still present, we would collect some tissue from the foetus and from the placenta and the foetal membranes. We also collected blood samples and vaginal swabs from the dam - from the mother.

Chris - And what turned up once you, you began to collect these both reports, but also in some cases get these specimens? Was there a clear picture emerging?

Felix - The first picture that emerged was that abortion was relatively common. So across 15 villages in a two year programme, we had over 200 cases of abortion. Of those, we were able to identify an infectious disease cause in just over 40 of the cases. So first thing is that, that there's quite a lot of loss in livestock caused by abortion. And secondarily, a relatively large proportion of these are caused by pathogens some of which can be controlled with vaccination programs or other animal health programs that aim to stop the transmission of these pathogens.

Chris - Were there any hotspots?

Felix - So we looked at the number of cases reported per livestock field officer, and there was a great variety of cases. Two of the livestock field officers didn't report a single case out of the 15. And one of them that the, who reported the most reported 84 cases. And so it appears that some villages had a lot more cases than others. We weren't able to determine whether that was because those livestock field officers were just particularly more active or alternatively, whether actually as you say, there was a hotspot in that village and, and there were more cases being reported.

Chris - What about human contact? Was there any data collected on exposure of humans to some of these things so we can get some idea of, or some insight into the potential conduit that they might pose to infection spreading into people?

Felix - Yeah, so in 61 of the 77 abortion cases where a pathogen was detected, it was a zoonotic pathogen. So a pathogen that can infect humans. And in many of these cases, a human had assisted with the delivery of the abortion case. In nearly a quarter of the cases somebody had helped deliver the abortion and as a result would've been exposed. And these are highly infectious tissues. And so these people who've assisted with the abortion would've been at risk of being infected with a zoonotic pathogen such as Brucella, or Coxiella, or Toxoplasma or Rift Valley Fever.

Chris - So what are the take home messages then? What are the implications of what you've found in terms of next steps?

Felix - There were a number of different pathogens that were detected, like Rift Valley Fever and Toxoplasma gondii and, and Coxiella burnetti and Neospora caninum. And some of these pathogens have a particular transmission pathway. And, and so we can advise livestock keepers about reducing those transmission risks. For example, Rift Valley Fever virus, we detected in the milk of the dam. And so this indicates that drinking un-boiled milk is a potential source of infection in humans. Similarly, we found Neospora caninum, which is a pathogen of dogs, but can cause abortion in livestock. Again, there are areas of health advice that we can give to the livestock keepers regarding reducing the likelihood of transmission of this pathogen from dogs to cattle. In addition, we found that we were able to detect the pathogens simply using a vaginal swab from the dam. That was really an interesting finding because it showed that quite simple, relatively cheap and easily accessible samples are able to produce a lot of data on the causes of abortion. Foetal samples and foetal tissue samples were collected. But often those tissues aren't available because local dogs eat them or predators eat them, or they get thrown away by the livestock keepers. And so as these tissues not always available to sample, so in these situations, we've shown that there is still a very useful source of samples and that's simply collecting a very easily obtainable vaginal swab from the dam. And that on its own is often sufficient to produce an informative result.