Safeguarding Pigs from Viral Threats: The Fight Against African Swine Fever in Nigeria

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Welcome to another episode of the Infectious Science podcast. This is Dr Matthew Daszho. Today we are continuing our conversation with an outstanding group of Nigerian clinicians and scientists that form part of the core of the West African Center for Emerging Infectious Diseases. In the last episode we started off by hearing from Dr Scott Weaver, professor and chair of microbiology and immunology at UTMB, about the West African Center, how that program got started and where they hoped to go moving forward. Then Dr Nathan Sheahu, a clinician scientist, and Dr Pam Luca, a veterinary scientist, shared their perspectives on emerging infectious diseases, one health and scientific collaboration. They also shared some stories about their careers, how they got to be doing the important work that they are doing to make the world a better, more safe place. In this part two of the Infectious Science on the Road in Nigeria series, dr Dennis Benta continues the conversation with West African Center for Emerging Infectious Disease colleagues Dr Pam Luca and his colleague Dr Loya Inca Asala, a scientist at the National Veterinary Research Institute, about African swine fever, the livestock production industry and producing vaccines for veterinary use in Nigeria.

Let's talk about another hemorrhagic fever, but not a zoonotic one. Let's talk about hemorrhagic fever in pigs. Let's talk about African swine fever. Pam, you've worked on African swine fever. You're still working on it. It's been in the news from China to Central Europe. Was recently discovered in Hispaniola, again after 30 years. Tell us a little bit about your work. The African swine fever.

African swine fever is actually a viral disease. It's not zoonotic but it's a disease of pigs that is caused by the African swine fever virus, because it was first reported in Africa, that was in Kenya in 1921. So African swine fever is like about a hundred years now. So after that first report it was thought to be an African thing And a lot of work has been done in that part of East Africa to Southern Africa, where it has also infected a lot of pigs, And eventually it moved to Europe, to Spain, Portugal. In the 60s It also got to the Caribbean at some point. All those ones got eradicated, I think before 2005, when it was reported in Georgia. Before then it was only endemic in the island of Sardinia in Italy. That was the only place that it was endemic at that time. But I think now when it got to Georgia, from Georgia to the Russian Federation and then before it moved to China and then before it came back to center Europe, then moving in and got into the wild boars, The challenge with African Swine fever is that when pigs get infected they actually die from it, Because hardly do you have survivors And when you do, some of them have been described as carriers, whether they shed or they don't shed, But I think the hypothesis is that they shed the virus in the environment. So you need to call them And when they come down, what you see is that if it's a subacute case, you just come into the pen and find pigs dead. But if it's an acute case, sometimes you come in and maybe you feed the pigs and then much later, when they are supposed to have eaten all the feed, you still find feed in their troughs And sometimes they huddle together. There's high fever And you could also have bleeding, and you also bleeding through the nose and things like that, And you could also have subcutaneous hemorrhages on the skin And before you know it, they also die. And those ones who will eventually recover, maybe chronic cases, like I said, and they go on to become carriers. So you wouldn't want carriers on your farm And because these are animals that are being consumed in high proportion, I think in terms of peak consumption globally, I think peak comes number one at some point. So a lot of people consume pork And if it's getting to your farm it's not something you can eliminate easily. So nobody wants to have airsave on this farm because of the volume of mortality that you have, And it also doesn't have vaccine and there's also no therapy. So the basic thing people do now is we encourage farmers on biosecurity. You know, if you have a good biosecurity you're going to keep the virus away from the farm, But if you have a very poor biosecurity, in terms of your practices, your hygiene, you're going to be at risk. So that's a disease that actually is not even transmitted by the peak itself. Human beings are seen as the major carriers or the major vectors in terms of the transmission of the virus, Although you also have the sylvatic cycle of the virus that has been transmitted by the onyxodoros, but that is a soft tick which has only been reported in East Africa and some part of Southern Africa. But for us here in West Africa is basically the domestic cycle, as the peak to peak transmission that we have. The vector has not really been established to be responsible for transmission.

So you have African swine fever in Nigeria.

Yes, we do. It was first reported in 1996 and since then it has been with us And we have terrible cases of African swine fever. And I think right now, almost on a yearly basis, we have reports of African swine fever. So it's there and that has been having its toll on farmers. And so, on a routine basis, what we do is that we receive samples from farmers When there are outbreak cases, samples are collected and sent to the lab for diagnosis and confirmation, which we do so that farmers will be able to be guided in what they do And the health authorities are also informed on what they need to do in terms of control measures.

So if the soft tick that's known to probably transmit but also maybe also maintain the virus in East Africa and South Africa is not present in Nigeria, where does the virus hide? Is it always consistently imported, Or is there some sort of an endemic cycle of African swine fever?

Yeah, it is endemic And sometimes it's maybe transmitted to formites, like I said, because you find in some places where farmers share a lot of farm implements or where a particular community will have a single boa that will be used to serve the other selves. So if that peak is infected, for example, the farm is infected, the virus is in the environment. You can easily get it because the virus is a little bit hardy. You know it's hardy but it's also liberal in terms of disinfectant. But it could also survive in the environment. It could survive in your sausages for a very long time at certain degrees, in fact in your minus 80, to survive for years. So if you have some of these infected animal products, it could serve in preserving the disease in the environment. And again, like I said, it's possible also that we have the tick around. But we have been trying to look for the ticks because they are nocturnal, they feed only at night, they don't have eyes, so they only come, feed on the peak and then drop off and hide in cracks and crevices. So it's wanting to look for those ticks Because, interestingly, there was a time we checked for antibodies to tick, salivary antigens And some of the ticks had those antibodies. So which means those peaks were exposed to tick bites, although not all of them had ASF, some, a few, maybe two, three which suggests that possibly the tick is around, but the role it plays in terms of transmission, that is yet to be established, but we can't rule that out.

Very interesting. So with African swine fever you said there's no treatment, so the animals have to be probably destroyed. I assume that in Nigeria you have wild boars are correct And they're probably persistent to or not as susceptible as the domestic pigs. is that correct?

We don't have wild boars. The wild boars are usually Europe. What we have are what hawks, what hawks, bush pigs And even those ones you know, people in Nigeria hunt a lot, so the population of those ones are not much in terms of, maybe, interaction between, let's say, the wild and human interface. It's not so much there. What we're thinking is responsible for the transmission. Maybe periodic outbreaks is as a result of human activities, but in terms of what hawks, bush pigs, red river hawks is not well established because there's no much contact with those ones. Usually you find them deep into the forest, deep into the wildlife reserve parks, so they usually don't have them coming close to human habitation. And I think there was a time people went in there to sample those ones and none has been tested positive. So we wouldn't want to say that they have a role for say, but what we think is that if from the domestic it gets into the wild, it also supports the Sylvatic circle.

One last question I had for you, maybe to wrap up that topic. Can you tell us about the pig industry in Nigeria? What is it compared to cattle, to chickens, and where and what parts of the country are the main producers?

The pig population is not like the cattle. I think we have about seven, eight million pigs in the country in terms of population And it's not evenly distributed really. You have more large-scale farmers in the southern part of the country and then up north you have small-scale farmers, those who keep in small numbers five to ten, maybe at most 50. And those ones are usually rural farmers who keep them in small numbers because it serves as a source of income When they are in need of money. they need to pay school fees, they need to take their children to hospital. they sell one, get quick money and then solve one or two problems. So the population here is not as high as down south, because in the south you have people keeping up to a thousand, two thousand pigs. Yeah, a single individual can have that number of pigs in his farm. It's a growing industry and I think a lot of people now have turned to eating pork and we also have a lot of Chinese who are coming in, so Chinese also patronize a lot of the pig industry. So it's a growing industry because the pig is considered as a very good bio-converter, because it converts any waste material. So people don't really put in much but you get something at the end of the day. So I would say it's a growing industry. But again up north we have the pig market. here The pig markets are in the north. We collect pigs from individuals from different locations into the central market and they are being purchased and taken down south where most of the consumers are. So at the end of the day, when you have those ones are infected and they're taken to the market and then some of them are sold. some are not sold. the ones that are not sold are taken back but they already be mixed with infected ones. So you take an infection back to your farm and then the ones that are taken down south, if they are being infected or have come in contact with infected pigs, they are also taken. So the pig market also serves as a mixing point for healthy and infected, and then healthy ones become infected Or they become carriers. so you end up contaminating the environment and other pigs also come down Very interesting.

Thank you, yeah.

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So we had the chance today to see the National Veterinary Research Institute and I saw that you're actually producing 20 vaccines locally, dr Asala. maybe you can tell us a little bit about what it takes to produce locally, and I'm especially interested in the vaccine acceptance and how do you distribute the vaccines to the end users. Is this an easy process? I know cost of vaccines is always an issue.

Yeah, for the National Veterinary Research Institute. Looking at our history, we will be 100 years in two years' time and actually how the city came to be was as a result of Rindapest that ravaged some parts of West Africa, the cattle population. So then we were under the British colonial rule and through the initiative, we're producing hyperimmune sera in order to tackle the disease. And so After Rindapest I think in 2011, nigeria finally declared free of Rindapest, so we're Rindapest free at the moment. So the course of the journey, other outbreaks of other diseases of importance came into being, like Newcastle, brucellosis and all that. And with that, vaccines were developed with expertise and support from also British government. And over the years, as time went on, we kept on improving on what we were doing. From using tissue culture we came to sell culture and actually we're still producing using the conventional vaccine technology. And with that, vorma's actually, or NVR has actually made a name and we have the only vaccine producing institution or establishment in Nigeria. And for the demand, in short, we are able to meet the national demand. So government also, or pharmacy, rely on importation of other foreign vaccines to be able to meet the demand. So for distribution and acceptance, in short, we're overwhelmed by requests and like we're always at our toes to produce, like I was in the meeting I had to leave three times because one call or the other one vaccine that needed to be dispensed And for us to facilitate distribution around the country. We have about 23 outstations, so we have our stations in 23 states out of the 36 where we have staff via which also render both diagnosis, also facilitate distribution. So we move vaccines from Vorma to such places and then it can easily be reached by farmers and also the staff and our outfit also render services to farmers, to farms. That way our vaccine coverage is national and sometimes we also have requests from sister colleagues like West Africa, for vaccines like against transbound diseases, like CBPP, fmt and that.

So Dr Luca was talking about the smaller big holders in the north, not so much the big markets or owners in the in the south. Do they have the means to afford these vaccines? I would imagine they are the lowest cost, but still is this for those smaller producers like doable?

Yeah, and for us, remember, we national institute, so our boxes are usually subsidized by the government, And then we have a lot of government interventions. At the moment, for instance, for the rabies and the rabies vaccine, there's a national campaign and we are to produce about 2 million doses of rabies vaccines and it's distributed free to all the states, and so all what the state government needs to do is just to mobilize strategies for vaccination. So every year we have a lot of states coming in to mitigate and give support to farmers by procuring vaccines from us, and the veterinary ministries or outfits will now go out to get those animals vaccinated. And even if you look at the cost of our vaccines, they're still relatively cheap and affordable, because compared to other foreign vaccines, maybe it's cheaper and those sizes are usually smaller, so that it can easily be affordable, because we are not really for profit if we look at it, because we have a lot of subversion and also support yearly from government in order to be able to produce these vaccines.

Okay, thank you very much.

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