Tag: disease

Why are people still dying of rabies?

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This article was written by Johanna Lindahl, researcher at the Department of Clinical Sciences; Division of Reproduction, SLU. The ïŹndings and conclusions in this blog post are those of the author and do not necessarily represent the views of SLU.

Stray dogs. Photo: Javad Esmaeili, pixabay

Imagine that you have two children. Both children are bitten by a dog that seems to have rabies, but you cannot know and now the dog has been killed. If the dog really had rabies, then the children will get it. If the children get a vaccination in time, they will not die. But the hospital is far away, the vaccine costs money and you can only afford to do this for one child, and maybe you will not make it on time. That money you would need for food for the family, and the rest of the family will suffer if you travel with one child. Maybe the dog did not really have rabies. Maybe the child that you chose to save will anyway not make it in time. What shall you do?

Rabies is a disease with 100% case fatality, but it is also a fully vaccine-preventable disease. So why are people still dying?

Globally, canine rabies is still one of the zoonotic diseases (diseases spreading to humans from animals) responsible for most human deaths (1). The vast majority of the 59 000 human deaths worldwide (2) are the result of bites from rabid dogs, with most deaths occurring in Asia (3–5). Children are most affected, probably because they are more easily bitten by dogs. In many countries, the number of cases is probably underestimated since there is no official rabies monitoring system. Since dogs are the main reservoir and source of infection for humans, vaccination of dogs is recognised as the most cost-effective and permanent solution to rabies prevention (6,7).

Numerous recent programmes have facilitated rabies control in low-resource settings, however these costly programmes have not yet achieved sufficient and sustainable vaccination coverage of 70%, which is required to eliminate canine rabies (8–10). Expansion of rabies elimination programmes in low-resource countries has been constrained by many factors:

  1. It is difficult to buy and transport the vaccines for injections, since they have to be kept cold all the time. Many countries have difficulties maintaining a cold chain, or reaching remote populations with vehicles.
  2. Many dogs are free roaming or aggressive and therefore difficult to catch and vaccinate.
  3. The dogs are often not living for very long, and therefore it is necessary to vaccinate all dogs in an area regularly to make sure that at least 70% of them are protected.
  4. Even when vaccinated, some dogs are in too poor condition for them to create enough antibodies to be protected. This can be because of malnutrition, or because of other infections, for example with parasites.

Even though vaccination of dogs is relatively expensive, the costs of human post-exposure vaccination, meaning vaccination that occurs after a person is bitten but before disease has started, is even larger. If given in good time, post-exposure vaccination will stop the disease from developing, but in many countries, there are not so many places where the vaccines are administered, and the victim has to pay for it themselves. As an example, in Cambodia people bitten by dogs can get the vaccine for free, but there are only three places in the whole country that provides this. Thus, most people that are potentially exposed to this horrible disease never gets vaccinated and may die undiagnosed in their home. Once a person develops the disease, there is nothing a hospital can do except to try to ease the symptoms. In many low and middle-income countries there is no provision for this, and the victim would be sent home to die.

Even if the reality is grim in many parts of the world, dog-transmitted rabies could be eradicated if enough dogs would be vaccinated, either by injections or by vaccine-baited food. So why has it not happened? The answer to this may lay in the lack of collaboration between human and veterinary sectors. This can be illustrated in this example from Europe: A person is bitten by a cat, imported from another country and not vaccinated. The veterinary authority agrees that it may be rabies, and the cat has to be autopsied to make the diagnosis. However, they judge it not urgent enough to pay for express transport and do the autopsy the same day, instead the animal will be autopsied the next Monday, after the weekend. However, the health sector, who has gotten the bitten patient, judge that they cannot take the chance, and initiate the post-exposure treatment, which not only has a high cost, but also some suffering for the patient. The savings done by the veterinary authority was minimal compared to the costs incurred by the hospital, resulting in higher costs for the government, which in the end funds both.

Vaccination costs for eradication of rabies in the dog population would be carried by the veterinary sector, and the savings would benefit the human health sector. This points to the need of a One Health approach with increasing collaboration between both sectors, for improved health for all. We can stop rabies, but we need to think outside our siloes and boxes and work together.

In our new project “Man’s best friend: A crossborder transdisciplinary One Health approach to rabies control in dogs in Southeast Asia”, led by the Zoonosis Science Centre at Uppsala University, we look at both dog population dynamics, antibody coverage, as well as the knowledge of people choosing to vaccinate their dogs to understand how we can improve the situation. This is done together with institutes in Vietnam, Cambodia and Lao. We aim to apply for more funds to also investigate alternatives with oral vaccination in the future, which hopefully can save more lives.

References

1.             Fooks AR, Banyard AC, Horton DL, Johnson N, McElhinney LM, Jackson AC. Current status of rabies and prospects for elimination. Lancet [Internet]. 2014 Oct 11 [cited 2018 Apr 3];384(9951):1389–99. Available from: https://www.sciencedirect.com/science/article/pii/S0140673613627075

2.             OIE. Report of the meeting of the OIE biological standards commission [Internet]. Paris; 2017. Available from: http://www.oie.int/fileadmin/Home/eng/Internationa_Standard_Setting/docs/pdf/BSC/A_BSC_Sept2017.pdf

3.             Taylor L, Nel L. Global epidemiology of canine rabies: past, present, and future prospects. Vet Med Res Reports [Internet]. 2015 Nov [cited 2017 Mar 7];Volume 6:361. Available from: https://www.dovepress.com/global-epidemiology-of-canine-rabies-past-present-and-future-prospects-peer-reviewed-article-VMRR

4.             Shwiff S, Hampson K, Anderson A. Potential economic benefits of eliminating canine rabies. Antiviral Res [Internet]. 2013 May 1 [cited 2017 Mar 24];98(2):352–6. Available from: http://linkinghub.elsevier.com/retrieve/pii/S0166354213000582

5.             Cleaveland S, Lankester F, Townsend S. Rabies control and elimination: a test case for One Health. Veterinary [Internet]. 2014 [cited 2017 Mar 25]; Available from: http://veterinaryrecord.bmj.com/content/175/8/188.short

6.             Wallace RM, Undurraga EA, Blanton JD, Cleaton J, Franka R. Elimination of Dog-Mediated Human Rabies Deaths by 2030: Needs Assessment and Alternatives for Progress Based on Dog Vaccination. Front Vet Sci [Internet]. 2017 Feb 10 [cited 2018 Apr 3];4:9. Available from: http://journal.frontiersin.org/article/10.3389/fvets.2017.00009/full

7.             Zinsstag J, Lechenne M, Laager M, Mindekem R, NaĂŻssengar S, OussiguĂ©rĂ© A, et al. Vaccination of dogs in an African city interrupts rabies transmission and reduces human exposure. Sci Transl Med [Internet]. 2017 Dec 20 [cited 2018 Apr 7];9(421):eaaf6984. Available from: http://www.ncbi.nlm.nih.gov/pubmed/29263230

8.             Elser JL, Hatch BG, Taylor LH, Nel LH, Shwiff SA. Towards canine rabies elimination: Economic comparisons of three project sites. Transbound Emerg Dis [Internet]. 2018 Feb 1 [cited 2018 Apr 3];65(1):135–45. Available from: http://doi.wiley.com/10.1111/tbed.12637

9.             Kayali U, Mindekem R, YĂ©madji N, Vounatsou P, Kaninga Y, Ndoutamia AG, et al. Coverage of pilot parenteral vaccination campaign against canine rabies in N’DjamĂ©na, Chad. Bull World Health Organ [Internet]. 2003 [cited 2018 Apr 3];81:739–44. Available from: https://www.scielosp.org/scielo.php?pid=S0042-96862003001000009&script=sci_arttext&tlng=

10.          Anyiam F, Lechenne M, Mindekem R, OussigĂ©rĂ© A, Naissengar S, Alfaroukh IO, et al. Cost-estimate and proposal for a development impact bond for canine rabies elimination by mass vaccination in Chad. Acta Trop [Internet]. 2017 Nov 1 [cited 2018 Apr 3];175:112–20. Available from: https://www.sciencedirect.com/science/article/pii/S0001706X16305101

How can we avoid another virus outbreak?

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By: Maja Malmberg, Researcher at the Section of Virology at the Department of Biomedical Sciences and Veterinary Public Health at SLU and Ekaterina Bessonova, Communications Officer at SIANI. This blog was originally posted at SIANI website

Photo: Peter Schaefer (EyeEm) / Getty Images.

Few of us have ever imagined living through a pandemic. With all the global progress and achievements in medicine, a contagion seemed like something from the dark ages. And here we are, battling a noxious virus that set foot in every country, bringing disease, disruption and dismay.

Covid-19 outbreak is still unfolding, and we are yet to fully experience its effect on our societies and lives. However, it’s worth looking into how this coronavirus came about and reflecting on what can be done to diminish the possibility of another pandemic.

How did Covid-19 emerge?

SARS-CoV-2 or Severe Acute Respiratory Syndrome Coronavirus 2, the virus that causes Covid-19, is most closely related to coronaviruses in bats, meaning it’s a zoonosis – a disease that pass from an animal or insect to a human.

Other examples of zoonotic diseases include such scary names as HIV, Zika and Ebola. But Covid-19 belongs to the same family of coronaviruses as SARS and MERS.

The outbreak of SARS in 2002 resulted in 8,098 cases and 774 deaths in 26 countries. Emerging in Saudi Arabia in 2012, MERS brought about 2,494 cases and 858 deaths in 27 countries. Both of them are thought to be bat viruses that got to humans through an intermediate host (civet cat and camel).

Comparing to its “family members”, SARS-CoV-2 has certainly been more effective in infecting humans – the number of reported cases has already passed over 400 000 and rising. The virus was only discovered in January 2020 and much more research is needed to fully understand it. Nevertheless, there are things we already know.

Thanks to its structure, which is essentially a spiky ball, the virus easily attaches to the surface of certain human cells, initiating infection. Unlike most of the respiratory viruses that infect either upper or lower airways, SARS-Cov-2 seems to infect both. Generally, upper-respiratory infections are easily transmitted and usually mild; lower-respiratory infections don’t spread as easily but are more severe. Additionally, the new coronavirus can be stable on surfaces for as long as 24 hours, which along with the fact that humans do not have immunity against it, facilitated such rapid spread around the world.

Exactly when and how the virus has first infected humans remains to be determined. It could have come from bats to humans directly or passed through another animal. Coronaviruses are famous for their ability to exchange part of its genome, the so-called recombination, something that makes them prone to change hosts.

Covid-19 is believed to originate from a wildlife market in Wuhan, China where alive wild animals were sold and butchered on the spot, usually using the same slaughtering tools for different species, which creates favorable conditions for the virus to jump from animals to humans. Such markets are a perfect melting pot for new viruses to emerge and spread. However, there are reports of early cases of Covid-19 in people with no links to the market, suggesting the initial point of infection may have been in a different place.

Photo: Ulet Ifansasti (Stringer) / Getty Images. 

Biodiversity, biosafety, bioinformatics: A virus risk management strategy

Prompt by the ongoing epidemic, China announced a permanent ban on wildlife trade and consumption. The global community greeted this measure as a major step, though the ban has already been criticized because it allows the trade of animals for fur, medicinal purposes and research. Additionally, China announced a similar ban in 2002 in connection to the SARS outbreak, but enforcement was relaxed after the epidemic was over and the trade rebounded.

Banning trade of wild animals is a straightforward measure to limit exposure to new pathogens. However, it is not the only reason behind the Covid-19 outbreak. Diminishing the emergence of new zoonotic diseases requires holistic strategies that reduce risks across several dimensions and make our societies more resilient to virus outbreaks.

First, all development strategies and activities must prioritize biodiversity and find a way to create jobs, generate incomes and increase wellbeing, without destroying nature.

The emergence of new pathogens tends to happen in places where a dense population has been changing the landscape – agricultural expansion, deforestation, construction, mining – all contribute to the loss of natural habitat. So, the area occupied by human activity is becoming larger, while wild animals are squeezed into shrinking spaces. That is why animals that wouldn’t normally come in contact with humans do so to a higher extent, increasing the risk for exposure and spread of viruses wild animals carry and that we have not experienced before.

For instance, recent research from the Swedish University of Agricultural Sciences (SLU) indicates that large forest fires can increase the spread of rodent-borne diseases in Sweden. However, the risks of emerging zoonotic diseases are especially high in the forested tropical regions experiencing rapid land-use changes and with high wildlife biodiversity.

Second, livestock industry and farmers have to implement adequate biosafety measures

Covid-19 sparked discussion about whether animal-based diets play a role in the emergence and spread of unknown and dangerous viruses. While there is plenty of research pointing that moderate consumption of meat has strong health and climate benefits, to what extent livestock production represents a risk of emergence of zoonosis depends on production management factors and country context.

For instance, small scale organic livestock farming is based on the principle that animals roam close to natural forests. This method is praised for animal wellbeing and lower environmental impact, but it makes contact between domestic animals and wildlife more likely. At the same time, industrial farms would usually keep animals isolated, creating conditions that prevent the spread of diseases from wild animals, however, because the animals are kept so densely to each other, diseases spread fast within the herd. Furthermore, plant-based diets that utilize a lot of commodities like almonds, soy, avocadoes and cocoa aren’t necessarily deforestation-free.

Another key point to consider is that vegan diets may not be the best option for people in low-income countries with high malnutrition. Milk, eggs and meat are highly nutritious, so many people keep animals at home for food and for insurance in times of need. There are also traditional pastoralist communities who live in drylands. For them animal husbandry is not only a source of food security, but also the core of culture.

For these reasons, increasing biosafety standards may offer a more appropriate way to reduce the risk of zoonotic diseases than excluding animal-based foods. Some common measures include keeping animals outside of the house, introducing designated areas for slaughtering and ensuring these facilities and people who work there practice well-executed hygiene and sanitation of all processes and equipment.

Third, funders need to ramp up investment in virology and bioinformatics, while the international community needs to improve cooperation, increase local capacities and raise awareness about these fields of knowledge.

The risk that new viruses can emerge and spread will always be there. But it is possible to minimize the losses by means of fast accurate detection and early response. Mapping the existing viruses in all animals will help us know what is out there and start developing technologies and strategies that can help us prepare and cope with possible outbreaks, pivoting from reactive to a proactive response. Advancing bioinformatics and virology will not only help us develop vaccines, but also anticipate pandemics through monitoring of threats while they are still evolving in animal populations.

Raising general awareness about what viruses are, how they spread and how one can protect from them is also key. Knowledge can conquer panic and prevent the creation and spread of conspiracy theories and fake news.