The IGH Podcast

Malaria is a disease usually associated with the tropics. However, avian malaria, caused by similar parasites, is distributed worldwide with the exception of Antarctica.

Avian malaria is spread by biting mosquitoes. The impact of the disease on bird populations varies. Some birds will not show any symptoms, but other populations can be driven to extinction by avian malaria. Zoos in particular have suffered from avian malaria outbreaks. London Zoo lost six penguins in 2012 and Longleat took the decision to close their penguin exhibit in 2018 after a second outbreak called into question the viability of keeping penguins. Despite these problems, little is known about the distribution of mosquitoes around zoos and their ability to infect birds with avian malaria.

This month we spoke to Arturo Hernandez Colina about his work looking into avian malaria in the UK.

Acute encephalitis describes a rapidly developing inflammation of the brain and, as you can imagine, is a neurological emergency. Not only is it a life-threatening disease with a mortality rate of up to 15%, it also presents a unique diagnostic challenge for doctors. Patients presenting to the emergency room with common symptoms of encephalitis such as fever, confusion or seizures, could have any number of other conditions which mimic these symptoms. With roughly 6,000 cases per year, encephalitis is relatively rare compared to, say, drug or alcohol misuse which can present in a similar way. As a result, Even once encephalitis is diagnosed there is a further complication. Inflammation can be caused by an external factor, in the case of encephalitis this is usually a virus, but it can also be caused by autoimmune disease in which the body develops an immune reaction against its own proteins. In cases of autoimmune disease, the aim of treatment would be to suppress the immune system and prevent it from causing further damage.

But if a virus is causing the encephalitis such a treatment would remove the body’s own defense mechanisms and worsen the patient’s condition. Therein lies the dilema for a doctor treating a case of encephalitis, they are presented with a condition of two possible causes with opposite treatments. This dilema would be easily resolved with a realiable diagnostic test that could differentiate between viral and autoimmune encephalitis. However, the cause of 37 to 62% of encephalitis cases is not identified, even after a thorough diagnostic investigation. With us today to talk about encephalitis and his work on diagnostic tests for encephalitis is Dr Mark Ellul. Mark is a Specialist Registrar in Neurology and Clinical Research Fellow funded by the Association of British Neurologists at IGH. He recently published a paper in Clinical Medicine “Acute encephalitis – diagnosis and management”, available at: http://www.clinmed.rcpjournal.org/content/18/2/155.abstract (http://www.clinmed.rcpjournal.org/content/18/2/155.abstract).

We’ve spoken in previous episodes about zoonotic diseases such as Leptospirosis and Echinococcus. The term zoonosis, which describes diseases that can affect both animals and people, was coined by a German scientist, Rudolf Virchow, working in the 19th century. Virchow could be considered the founder of the One Health approach to medicine and research. He stated that “Between animal and human medicine there are no dividing lines – nor should there be. The object is different but the experience obtained constitutes the basis of all medicine”. This concept that human health is inextricably linked to that of animals is the central tenant of One Health which aims to design and implement research, programmes and policy to improve public health. This approach requires collaboration across a wide variety of disciplines from the medical and veterinary fields. The result is a series of large research projects involving multiple research institutes across several countries.

One Health projects can have a particularly big impact in areas where people’s income, welfare and opportunities are highly dependent on their livestock. One such area is the Horn of Africa, the north-eastern part of Africa that includes Eritrea, Djibouti, Somalia, Ethiopia and Kenya. The One Health Regional Network for the Horn of Africa, or HORN project, was established to improve the health and wealth of people living in the Horn of Africa by creating a research network that will focus on the link between human and animal health. This research network connects scientists working at universities in Liverpool, Eritrea, Ethiopia, Somaliland and Kenya who work together on projects to address the problems of developing countries. With funding from the Global Challenges Research Fund, the HORN project aims to build research capacity in target countries by training both academic and non-academic staff. The funding is also used to carry out research projects with local students who are mentored and supported by both local and UK academics.

With us this month to discuss the HORN project is Professor Matthew Baylis, the lead investigator on the project.

Parasites come in all shapes and sizes. Some of them can live in their host without causing symptoms whilst others cause debilitating and sometimes fatal disease. A few episodes ago, we talked about lungworm in cattle. While lungworm can affect other species as well, like deer and buffalo, they tend to be closely related to cattle. However, other parasites make a habit of infecting different species as part of their lifecycle. Rather than having a free-living life cycle, which leaves them at the mercy of the elements, they take up residence in an intermediate host. Here they are relatively safe and can busy themselves preparing to infect their definitive host where another round of reproduction will take place.

 

A good example of these types of parasites are Echinococcus, a genus of Cestodes which are more commonly known as tapeworms. This type of tapeworm tends to use livestock as an intermediate host and predatory species, such as canids, as their definitive host. They have an important role in human health too. If a person eats an Echinococcus egg, the parasite can infect them as if they were the intermediate host, causing severe disease. This ability to cause disease in a wide variety of species means that control measures must encompass all affected species in order to provide adequate protection.

Marisol Collins is coming to the end of her PhD, during which she has worked on the HyData Project to investigate the distribution of Echinococcus granulosus in the UK. This has involved looking at the potential for Echinococcus transfer in different populations of canids including hunting hounds and zoo animals

Dogs are currently the most popular pet in the UK forming 26% of the pet population. Pet ownership has been associated with health benefits such a reduced blood pressure, increased exercise and reduced feelings of loneliness. However, dog bites are also believed to be on the increase and, over the last five years, Merseyside has become the dog bite capital of the UK with the greatest number of dog related hospital admissions per 100,000 population. Recently reported figures suggest that at least 20 people are hospitalised due to dog bites every day in England and Wales. Dog bites can have a devastating impact on all parties involved. Most obviously, the person bitten is left with a physical injury and, perhaps a lasting fear of dogs. These can lead to personal economic losses through time off work. The dog itself is often euthanised after a serious bite which in turn impacts the owner. Even if the dog isn’t euthanised, it may be confiscated or given up to a shelter since the owner feels they can no longer be trusted. All of these come with a cost to society, for example, the estimated bill for police kennelling of potentially dangerous dogs in 2015 was £5 million pounds. Studying dog bites and how they happen is an important part of developing strategies to prevent them.

Sara Owczarczak-Garstecka is a PhD student at IGH working on a project: “Dog bites; Perception and Prevention”. As part of her studies she looked at YouTube videos that captured dog bites and statistically analysed their characteristics to show how canine and human behaviour changes before a bite. Her results have been published in an article in Nature Scientific Reports entitled ‘Online videos indicate human and dog behaviour preceding dog bites and the context in which bites occur.’ available via this link: https://www.nature.com/articles/s41598-018-25671-7 (https://www.nature.com/articles/s41598-018-25671-7).

The bovine lungworm, or Dictyocaulus viviparus, inhabits the lungs of cattle causing a disease known as husk. The symptoms include coughing and an increased breathing rate. Severely affected cows may be reluctant to move and struggle to breath with some heavy infections leading to death. Of course, all of these symptoms are accompanied by production losses and decreased animal welfare which both have an impact on farmers. The cost of an outbreak has been estimated at about £140 per cow in the herd.

Traditionally, lungworm was a disease which affected young cattle in the south-west and the Midlands. Over the few decades there has been a shift in the pattern of lungworm epidemiology with an increase in Scotland and northern England. In 2014 the Department for Environment, Farming and Rural Affairs and the national disease surveillance networks such as APHA released a statement expressing concern at the increased incidence of lungworm in these areas. Not only did the number of cases increase, but there were more cases in adult cows, potentially increasing the economic damage caused during an outbreak.

Here to discuss the changing picture of lungworm epidemiology is Cat McCarthy. She is coming to the end of her PhD during which she has developed a forecasting tool to predict lungworm outbreaks. This tool is based on laboratory work examining how lungworm larvae react to different temperatures and rainfall conditions. She recently published an article “Controlling lungworm disease in dairy cattle” in “In Practice” available via this link: https://inpractice.bmj.com/content/39/9/408 (https://inpractice.bmj.com/content/39/9/408).

Leptospirosis is an important disease worldwide. Not only does it affect seven to ten million people annually, it also infects animals causing economic and personal loses. The disease itself is caused by a genus of bacteria called Leptospira with up to 13 different genetic types of Leptospira able to cause disease. In the UK, an important reservoir for leptospirosis is cattle. Not only does this cause problems in terms of cattle health, but can also pose a public health risk to the farmers who look after them.

In terms of cattle health, leptospirosis can be tricky to diagnose and treat. The symptoms, such as reduced milk production, abortion, weak calves and other fertility problems, are not unique to leptospirosis so can be challenging to diagnose. What’s more, not all cattle with show obvious clinical signs with some affected by subclinical disease which is difficult to detect. Further complicating the picture is the fact that Leptospira can live in the kidneys of recovered cows for years without causing disease, but still infecting other individuals in the herd. A recent survey found that up to 60% of UK farms tested positive for leptospirosis.

Many cattle in the UK are vaccinated against leptospirosis. The current leptospirosis vaccine is an “inactivated” vaccine in which Leptospira unable to cause disease are injected into the cow to stimulate an immune response and immunity. While this produces good immunity to the type of Leptospira in the vaccine it doesn’t necessarily provide protection, or cross-protection, against other strains or species of Leptospira. This lack of cross-protection is one of the weaknesses of the current vaccine. There is a real need for more modern vaccines against Leptospira to be developed. One of the scientists working in this field is Intan Kamaruzaman, a PhD student at IGH. She is currently looking at alternatives to the current vaccine using a reverse vaccinology approach.

Antimicrobial resistance is one of the major challenges facing us today. Not only does it have implications for human medicine and disease control but how and when we decide to use antibiotics to treat disease in animals. The agriculture industry has come under widespread pressure to reduce and replace antibiotics in food production animals.

However, antibiotic use is widespread in small animal medicine too. One important aspect of tackling antimicrobial resistance is understanding when antibiotics are prescribed and identifying areas in which their use can be reduced. Farmers should keep detailed records of antibiotic use, but there is used to be no integrated system for collecting data associated with antibiotic use in small animals. In 2008, the Small Animal Veterinary Surveillance Network or SAVSNET was set up by the British Small Animal Veterinary Association and the University of Liverpool. Since then SAVSNET has expanded to include over 200 veterinary practices at around 450 premises submitting anonymised information about consults they have attended.

With us to talk about SAVSNET and finding patterns in such a vast database is PhD student David Singleton.

Lameness in dairy cattle is a well known issue with plenty of research exploring the effects on animal health and welfare, as well as the economic impact for farmers. However, lameness in the UK beef herd is less well characterised. Identifying the current levels of lameness and the main causes is the first step in developing an approach to reducing lameness in beef cattle. Another essential aspect is farmers’ perceptions of the problem. Ultimately, the farmer is responsible for the health and welfare of their animals. In terms of reducing lameness, farmers’ efforts to reduce disease incidence might be hampered if they haven’t recognised lameness as a problem or have trouble identifying clinical cases. This month we talked about lameness in beef cattle, and farmers’ perceptions of the problem with Jay Tunstall, a PhD student at IGH who recently published a paper entitled “Lameness in Beef Cattle: UK Farmer’s Perceptions, Knowledge, Barriers and Approaches to Treatment and Control.”

https://www.frontiersin.org/articles/10.3389/fvets.2019.00094/full (https://www.frontiersin.org/articles/10.3389/fvets.2019.00094/full)

The brown rat doesn’t have a good reputation in our culture. This episode probably won’t do much to help their cause and shed the popular perception of the rat as a disease-carrying pest. Although they’re intelligent and social animals that love to be tickled and can make great pets, they are known carriers of several different diseases.

Some of these pose no threat to humans or their livestock, but others are known or possible disease causing agents. As a result, it’s important to monitor which viruses and bacteria are circulating in wild rodent populations so we can act before they cause a problem. Once we know that a virus or bacteria is present in wild rodents and could cause a threat, we can take steps to prevent that from developing.

Here to tell us about her work looking at the viruses and bacteria in wild rodent populations is Ellen Murphy. She’s coming to the end of her PhD at the moment and is busy writing up her thesis, but she’s kindly agreed to tell us about her research.