Airborne Dust / Zoonosis / Land Use

This forum is to discuss general things concerning TSOI.
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Re: Airborne Dust / Zoonosis / Land Use

Post by trader32176 »

Domestic dogs unlikely to transmit SARS-CoV-2, say researchers

2/19/21 ... chers.aspx

Researchers in Spain and Germany have conducted a study showing that domestic dogs are unlikely to contribute to the transmission and community spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) – the agent that causes coronavirus disease 2019 (COVID-19).

Infection with SARS-CoV-2 has recently been reported among various different species, including domestic cats and dogs. In addition, veterinarians in Spain detected an increase in severe lung pathologies in domestic dogs during the spring months of the year 2020.

These developments led the researchers to investigate whether SARS-CoV-2 infection could be playing a role in canine lung pathologies. The team also investigated whether domestic dogs are susceptible to infection in the home environment and whether they can contribute to community spread of the virus.

The team checked for the presence of SARS-CoV-2 infection and anti-SARS-CoV-2 antibodies in 40 dogs with pulmonary pathologies and 20 healthy dogs from households where at least one member was infected.

As reported in the journal Veterinary Research, all dogs included in the study tested negative for SARS-CoV-2 infection by real-time quantitative reverse transcription polymerase chain reaction PCR (RT-qPCR).

However, one of the 40 unhealthy dogs and five of the 20 healthy dogs tested positive for anti-SARS-CoV-2 antibodies.

The team says the findings suggest that that, even in cases of canine infection with SARS-CoV-2, the virus would be poorly transmissible.

More about coronaviruses in animals and humans

The novel SARS-CoV-2 virus belongs to the betacoronavirus genus, one of the four genera (alpha-, beta-, gamma- and delta-) that make up the coronavirus family.

The alpha- and betacoronaviruses, which infect both animals and humans, have also been detected in dogs and cats.

Mostly, they are responsible for respiratory infections in humans and gastroenteritis in animals,” says the researchers.

However, canine respiratory coronavirus (CRCoV), which is also a betacoronavirus, can cause respiratory symptoms in dogs and sometimes occurs as a coinfection with other respiratory pathogens.

SARS-CoV-2 infections have been reported in various different species

Since the SARS-CoV-2 outbreak began in Wuhan, China, in late 2019, many infections have been described in cats, dogs, tigers, lions, minks and ferrets, all of which were reported to have had close contact with infected people.

The team says that no cases of zoonotic SARS-CoV-2 transmission from domestic animals to humans have yet been described.

In fact, some studies have reported cases of dogs belonging to infected owners testing negative for anti- SARS-CoV-2 antibodies, suggesting that domestic dogs might not even be carriers of the virus.

By contrast, other studies have reported cases of companion dogs testing positive for SARS-CoV-2 infection by RT-qPCR.

“Dogs are currently considered to be less susceptible hosts for SARS-CoV-2 than cats or minks, despite the fact that several positive RT-qPCR test results in dogs have been reported,” say the researchers.

“However, veterinarians in Spain have observed an increase in aggressive lung pathologies in dogs during the human COVID-19 pandemic that have not responded to conventional antibiotic treatments,” they add.

What did the researchers do?

To determine whether SARS-CoV-2 might play a role in these pathologies, the team conducted a prospective study of 40 dogs (aged a mean of 8 years) presenting with pulmonary pathologies between April and June 2020 in Spain.

All of the animals underwent chest X-rays, ultrasound analysis, and computed tomography. This revealed severe alveolar or interstitial patterns with pulmonary opacity, parenchymal abnormalities, and bilateral lesions.

Nasopharyngeal and rectal swabs taken from the animals were tested for the presence of SARS-CoV-2 by RT-qPCR, and several immunoassays were performed to test for anti-SARS-CoV-2 antibodies.

A further healthy 20 dogs from households where at least one person had been diagnosed with SARS-CoV-2 were also tested.

What did the study find?

All 40 dogs presenting with lung pathologies, and all 20 healthy dogs tested negative for SARS-CoV-2 infection by RT-qPCR.

Thirty-three of the unhealthy dogs underwent further testing for infectious canine pathogens, which revealed infection with the bacterium Mycoplasma spp. in 26 cases.

SARS-CoV-2-specific immunoglobulin G (IgG) antibodies were detected more frequently among the healthy dogs from SARS-CoV-2-positive households than among the dogs with lung pathologies (five dogs versus one dog), which the team says might indicate the susceptibility of these exposed dogs to infection.

However, all six of the SARS-CoV-2-specific IgG-positive animals still tested negative for infection by RT-qPCR, the team points out.

Here we report that despite detecting dogs with anti-SARSCoV-2 IgG, we never obtained a positive RT-qPCR for SARS-SoV-2, not even in dogs with severe pulmonary disease; suggesting that even in the case of canine infection, transmission would be unlikely,” writes the team.

“Moreover, dogs with owners positive for SARS-CoV-2 could have been more likely to be exposed to infection during outbreak,” they conclude.

Journal reference:

Perisé-Barrios, AJ, et al. Humoral responses to SARS-CoV-2 by healthy and sick dogs during the COVID-19 pandemic in Spain. Vet Res 52, 22 (2021)., https://veterinaryresearch.biomedcentra ... 21-00897-y
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Re: Airborne Dust / Zoonosis / Land Use

Post by trader32176 »

Evolution of the spike gene of SARS-CoV-2 for human adaptation

2/21/21 ... ation.aspx

The rapid spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has infected over 111 million individuals worldwide and has resulted in the COVID-19 pandemic. Many pangolin and bat-derived viruses are closely related to SARS-CoV-2, which suggests its likely zoonotic origin.

Researchers have found a 96% similarity in nucleotide sequence between bat coronavirus (RaTG13), isolated in China, and SARS-CoV-2 and ~97% amino acid similarity with the Spike (S) protein. This S protein performs two essential roles, i.e., mediates receptor-binding and membrane fusion. Hence, spike protein is regarded as a key coronavirus determinant of host tropism.

Similarly, a high percentage of similarity was also found in viruses present in Manis javanica (pangolins). A 97.4% amino acid concordance has been reported to be present in the receptor-binding domain (RBD) of the spike protein found in the pangolin virus.

A study of various epidemics over a couple of decades, i.e., the emergence of swine acute diarrhea syndrome coronavirus (SADS-CoV), severe acute respiratory syndrome coronavirus (SARS-CoV), and Middle East respiratory syndrome coronavirus (MERS-CoV) have shown the world the epidemic potential of coronaviruses.

Scientists have explained that a minor change in the virus's genetic sequence may play a crucial role in its adaptation to a new host. A minor modification in only two amino acids established a necessary change in SARS-CoV and MERS-CoV spike proteins required to adapt to human beings.

A similar change was also found in many other viruses, such as Ebola, where a single alanine-to-valine mutation at position 82 in the glycoprotein initiated their human adaptation, which caused the outbreak. Many recent outbreaks associated with an RNA virus, for example, West Nile virus, Zika virus, and Chikungunya virus, also occurred due to a single amino acid change in the virus nucleotide sequence.

In the case of SARS-CoV-2, a single mutation at position 614 in the S protein caused a change in the production of single aspartic acid to glycine, which has resulted in an increase of replication vigor in humans. However, the genetic determinants of SARS-CoV-2 responsible for the change of its host from animal to human remained unknown.

Scientists believe a strong signature of positive selection occurs when a virus changes its host through rapid evolution or cross-species transmission.

Such incidence was reported for the brief SARS epidemic that took place in 2002–2003. During this period, a series of adaptive changes or mutations occurred in SARS-CoV genomes characterized based on dN/dS tests.

These tests are designed for the comparison of eukaryotic interspecies. However, the limitation of these tests is that they cannot detect the hallmark signature of positive selection in viral lineages with small sequence divergence.

Recently, researchers have used highly sophisticated methods that are capable of detecting selective sweeps. In this method, a selectively favorable mutation spreads through the population, causing a reduction in the level of sequence variability at nearby genomic sites.

With the help of unprecedented statistical tools, scientists have analyzed more than 182,000 SARS-CoV-2 genomes and found that positive selection plays a vital role in the adaptive evolution of SARS-CoV-2. Considering the coronavirus host tropism, researchers provided strong evidence that the spike protein residue 372 contributes to adaptive mutation, which in turn aggregates their replication in human lung cells. The research by scientists in the U.S and Israel is posted online on the bioRxiv* preprint server.

The genetic modification, i.e., threonine-to-alanine change, may enable the virus to replicate more vigorously within human cells. This also promotes an efficient human-to-human transmission.

Prior computation-based research and the study of pseudotyped viruses have identified positive selection in SARS-CoV-2.

Even though a study of the pseudoviruses provided vast volumes of useful information, the entire life cycle of the virus or the interactions between different viral proteins and the host were not obtained. Recently, the use of live viruses has helped the development of hamster models that recapitulate human-to-human transmission.

In summary, current research shows the presence of a distinct footprint of positive selection around a non-synonymous change (A1114G; T372A) within the RBD of the SARS-CoV-2 spike protein. This plays a vital role in incapacitating species barriers and also achieving interspecies transmission from animals to humans.

Further, the structural analysis also indicates that the change of threonine with alanine in SARS-CoV-2 removes the glycosylation site at N370. Such changes indicate a favorable binding of the virus to the cellular receptor in humans (ACE2).

Another interesting suggestion was that, unlike previous assumptions, the Huanan seafood market, China, might not be the origin point of the novel SARS-CoV-2. The transmission may have occurred unnoticed elsewhere for a period that provided the ancestor virus enough time for their adaptation to human replications.

*Important Notice

bioRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

Journal reference:

A selective sweep in the Spike gene has driven SARS-CoV-2 human adaptation Lin Kang, Guijuan He, Amanda K. Sharp, Xiaofeng Wang, Anne M. Brown, Pawel Michalak, James Weger-Lucarelli bioRxiv 2021.02.13.431090; doi:, ... 3.431090v1
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Re: Airborne Dust / Zoonosis / Land Use

Post by trader32176 »

Research predicts which mammal species can spread SARS-CoV-2

2/23/21 ... CoV-2.aspx

Scientists worldwide are fighting to contain the ongoing COVID-19 pandemic, which has already claimed more than 2.48 million lives. Preventing spillback infections is essential to containing the pandemic. To do so, it is vital to understand the nature of the virus, i.e., its susceptibility to a range of hosts.

Like previous disease outbreak episodes, SARS-CoV-2 originated from the spillover of a zoonotic pathogen. This virus's high transmission rate is attributed to its capability to use a highly conserved cell surface receptor, angiotensin-converting enzyme 2 (ACE2), to enter the host cell.

The ACE2 protein is predominantly present on the cell surface of all major vertebrate groups. The high rate of spillback infections in the past year can be explained by the simultaneous occurrence of three factors – (a) a high human population, (b) high infection potential of SARS-CoV-2, and (c) the ubiquitous nature of the ACE2 receptor.

Now, a new study, published on the bioRxiv* preprint server, has revealed the importance of spillback infections during pandemics. During spillback infections, the SARS-CoV-2 virus was observed to have been transmitted from humans (host) to other mammals. Such spillback infections may lead to the establishment of a new host (animals), which may act as a virus reservoir. These animals may, subsequently, cause a secondary spillover to humans.

Such an occurrence was found in Denmark and in the Netherlands, where SARS-CoV-2 was transmitted from humans to farmed mink, and afterward, a variant of the virus was transmitted back from the mink to humans.

The secondary spillover poses a significant threat as it generates mutant strains. A variety of pets, farmed animals, etc., are reported as new hosts of SARS-CoV-2. The emergent strains may be more virulent than the existing ones. A prior study of the recent spillover event has revealed that the mink-derived variant can decrease sensitivity to neutralizing antibodies. This indicates that the efficacy of vaccines may also take a toll.

Scientists have carried out various computational studies to make valid predictions about non-human animals susceptible to SARS-CoV-2. To this end, both comparative models of ACE2 orthologs sequences among various species and structure-based models of the viral spike protein bound to ACE2 orthologs were used.

The current study develops a new model by combining structure-based inference with species-level trait data. This would help predict the zoonotic capacity of different animal species in becoming zoonotic hosts of SARS CoV-2.

To enhance the predictive capacity of the models across species, scientists have incorporated intrinsic biological traits of ~5400 mammal species in their study.

In the course of model development, several factors that are associated with species susceptibility to SARS-CoV-2 were considered, for example, the binding strength between SARS-CoV-2 receptor binding domain and host ACE2. The combined modeling system has helped increase the accuracy percentage of prediction of zoonotic capacity to 72%.

The model has predicted a high SARS-CoV-2 zoonotic capacity for many domesticated, farmed, and live traded animal species. For example, among all livestock, Bubalus bubalis (water buffalo) was predicted to have a high zoonotic capacity. Some of the other species that showed a high percentage of zoonotic capacity are rats, rodents, and bats. Endangered species such as mountain gorillas and addax also have a high zoonotic capacity, thereby putting the individuals directly involved in active conservation management at greater risk of spillback transmission. The model has also helped to identify various other animal species that can act as hosts to SARS-CoV-2.

Despite a high level of agreement between these models and empirical studies' predictions, some differences remain between the computational results and the actual experiments, including animals. As an example, several computational predictions suggested that Sus scrofa (pigs) show susceptibility to SARS-CoV-2, but this result did not hold up in animal-based experiments.

Scientists believe that the disagreement between the real-world observations and in silico predictions of zoonotic capacity stems from the fact that the host susceptibility and transmission capacity are not the sole determinants. Transmission of the virus also depends upon the host's cellular environments, i.e., host immunogenicity, protein receptors, etc., where the virus's replication takes place. Further, other challenges such as limitations in the ACE2 sequences and species trait data also aid in predicting error.

Therefore, researchers have recommended that a single methodology is not sufficient to predict the zoonotic capacity of SARS-CoV-2. The zoonotic predictive capacity could be increased by assessing the results obtained from combining theoretical models, statistical models, laboratory experiments, and real-world observations.

*Important Notice

bioRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

Journal reference:

Predicting the zoonotic capacity of mammal species for SARS-CoV-2 Ilya R. Fischhoff, Adrian A. Castellanos, João P.G.L.M. Rodrigues, Arvind Varsani, Barbara A. Han bioRxiv 2021.02.18.431844; doi:, ... 8.431844v1
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Re: Airborne Dust / Zoonosis / Land Use

Post by trader32176 »

Free-ranging minks exhibit high titers of SARS-CoV-2 antibodies in Utah

2/28/21 ... -Utah.aspx

Zoonotic diseases have caused outbreaks and epidemics throughout history. The current coronavirus disease (COVID-19) pandemic is one of the worst pandemics in the world.

The coronavirus pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), first emerged in Wuhan City, China. The outbreak was reported in a seafood market, where wildlife trade occurs. One of the virus's potential intermediate hosts is the pangolin, which may have acquired the virus from bats.

Apart from pangolins, camels, and civet cats, another possible host of the virus are minks.

Researchers at the U.S. Centers for Disease Control and Prevention (CDC) report outbreaks of coronavirus disease (COVID-19) on mink farms in Utah, United States. They surveyed around farms for evidence of exposure and found high SARS-CoV-2 titers, suggesting a possible viral transmission pathway to native wildlife.

Wildlife epidemiologic investigation

The researchers reported a wildlife epidemiologic investigation of mammals captured on or near properties in Utah, where outbreaks of SAR-CoV-2 were assumed to occur in farmed mink.

Mink farming is a popular and common industry in the U.S. Most of the farms are family-owned. Amid the coronavirus pandemic, the U.S. Department of Agriculture's Veterinary Services Laboratories confirmed SARS-CoV-2 infection in mink at two Utah farms in August 2020.

From there, more outbreaks were confirmed at many farms not only in Utah but also in Wisconsin, Michigan, and Oregon. Although epidemiologic investigations are being processed, scientists believe that infected farmworkers are the potential source of the virus.

The study

To arrive at the study, published in the CDC's Emerging Infectious Diseases journal, the team captured free-roaming mammals from August 22 to 30, 2020. They used Tomahawk and Sherman traps placed outside barns and barrier fences.

The team obtained oral, nasal, rectal swabs, blood samples, and tissue specimens from the animals. All the samples collected were sent to the National Veterinary Services Laboratories, while tissue specimens were sent to the U.S. Geological Survey National Wildlife Health Center for testing.

SARS-CoV-2 viral RNA was tested in the samples by real-time reverse transcription-polymerase chain reaction (RRT-PCR). Virus neutralization assays were used to test serum samples.

Overall, the team captured 102 mammals, 78 are rodents and 24 are mesocarnivores. Rodent species composed of 45 deer mice, 5 Peromyscus spp. Mice, 25 house mice, and 3 rock squirrels. Mesocarnivore species consisted of presumed escaped American mink, 2 presumed wild American mink, 5 raccoons, and 6 striped skunks.

Of the minks captured, 11 tested positive for SARS-CoV-2 antibodies. No other animals had detectable antibody responses. This means that the minks were previously exposed to SARS-CoV-2 and got infected.

Of those minks with a positive result, three had a high cycle threshold detection.

"Although we did not find evidence for SARS-CoV-2 establishment in wildlife, the discovery of escaped mink with the opportunity to disperse and interact with susceptible wildlife, such as wild mink or deer mice, is concerning," the researchers explained in the study.

Escaping minks into the wildlife may pose a threat to wild minks. Since they are susceptible to SARS-CoV-2 infection, they can be potential reservoirs of the virus. This could lead to future outbreaks of COVID-19, which has now infected over 28.6 million cases in the U.S. alone, with more than 513,000 deaths.

"Heightened biosecurity and best management practices would help prevent accidental releases of infected animals or spillover of SARS-CoV-2 from susceptible species to native wildlife," the researchers added.

Reverse zoonosis could also play a role in the spread of viruses. It involves the transmission of a virus from humans to animals. Since the spread could pose health threats to both humans and animals, wildlife and farm surveillance of minks is crucial.


COVID-19 Dashboard by the Center for Systems Science and Engineering (CSSE) at Johns Hopkins University (JHU) - ... 7b48e9ecf6

Journal reference:

Shriner, S., Ellis, J., Root, J. et al. (2021). SARS-CoV-2 Exposure in Escaped Mink, Utah, USA. Emerging Infectious Diseases.
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Re: Airborne Dust / Zoonosis / Land Use

Post by trader32176 »

Time to implement measures preventing future viral zoonoses

2/28/21 ... noses.aspx

The coronavirus disease (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), continues to spread globally, infecting over 114 million people. The virus first emerged in late December 2019 in Wuhan, China, from a potential animal host.

Zoonotic diseases have caused outbreaks throughout history, claiming millions of lives. These diseases occur when pathogens from animals jump to humans and cause illness.

Now, researchers at the University of Silesia in Katowice and the Poznan University of Medical Sciences in Poland recommend measures to prevent future zoonotic outbreaks. They emphasized the importance of viral surveillance and research on new viral strains as primary strategies to combat these infections.

The coronavirus pandemic

The coronavirus pandemic first emerged in Wuhan City, China in December 2019. Since then, it has spread to 192 counties and regions. It has caused a significant burden to healthcare systems, the economy, and public fears.

The pandemic served as a lesson and call-to-action for many countries and health agencies to minimize the risk of future viral pandemics. Acting early when an outbreak surface is crucial to reduce the negative impact of the illness.

Zoonotic viral infections

Zoonotic viral infections represent a critical global health issue. Due to various reservoirs and vectors, it is challenging to track transmission dynamics and impose control and preventive measures.

Throughout history, some of the worse outbreaks the world has experienced were diseases that came from animals. These include the H1N1 swine flu, bubonic plaque, coronavirus outbreaks like severe acute respiratory syndrome (SARS), the Middle East respiratory syndrome (MERS), and the current COVID-19, and the human immunodeficiency virus (HIV) infection, among others.

The spillover of viruses and pathogens from animals to humans and from human to human is extremely rare. However, spillover events can occur and cause widespread infections.

The study

The current study, published in the journal Science of The Total Environment, highlights several directions through which the transmission and spread of pathogens from animals to humans can be prevented or mitigated.

Further, the study elaborated on the role of surveillance systems. It also explains the importance of identifying viral pathogens in animals, reducing ferret farming, changes to wild trade regulations, modifications to the meat production process, and limitations to hunting activities.

The study explains how monitoring and identifying novel viral agents can help reduce outbreaks in the future. Surveillance of viral groups tied to animal hosts is essential in understanding current and future epidemiological risks.

Past studies point to the zoonotic origin of SARS-CoV-2, with bats being the primary reservoir for its lineage. From bats, scientists believe the virus jumped to an intermediate host before infecting humans. The intermediate host speculated to have transmitted the virus to people in the seafood market in Wuhan City was a pangolin.

In previous coronavirus outbreaks, like SARS and MERS, the intermediate hosts were noted to be civet cats and camels, respectively. Considering this, there is an urgent need to continue to screen the bat-associated coronaviruses, identify hotspots, isolate particular strains, and evaluate their potential for cross-species transmission. All these will help prevent another outbreak in the future, which may evolve into a pandemic.

The study also highlights the importance of limiting wildlife trade to prevent future zoonotic outbreaks. Today, the international trade of wild animals is currently regulated, wherein countries can implement provisions. However, due to the illegal wildlife trade, the risk of another pandemic is possible.

Hence, limiting or banning wildlife trade is essential. Countries can also regulate illegal trades happening in their territories to protect not only animals but also people.

The study also discussed mink farming as a potential source of zoonotic diseases. It is known that species from the Mustelidae family are vulnerable to the infection of beta-coronaviruses. Ferrets are usually used as animal models for coronavirus studies.

Meanwhile, the American mink is also susceptible to some coronaviruses, such as SARS-CoV-2. Today, the highest production of mink is Denmark, China, the Netherlands, Russia, and the United States.

Though the worldwide resignation from mink farming is unlikely in the future, some areas have noted its decline. Such decisions will have a positive ecological impact since mink production has been tied to increased nitrous oxide (N2O) emissions, eutrophication, and water consumption.

Other factors that may drive future outbreaks include meat production and hunting activities. Changing practices and regulating these activities can reduce the risk of future coronavirus outbreaks.

“The present paper considers different strategies, the implementation of which would not only be beneficial from a healthcare point of view but in selected cases could also have positive socio-economic, ethical, and environmental outcomes,” the researchers concluded in the study.


COVID-19 Dashboard by the Center for Systems Science and Engineering (CSSE) at Johns Hopkins University (JHU) - ... 7b48e9ecf6

Journal reference:

Halabowski, D., and Rzymski, P. (2021). Taking a lesson from the COVID-19 pandemic: Preventing the future outbreaks of viral zoonoses through a multi-faceted approach. Science of The Total Environment. ... via%3Dihub#!
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Re: Airborne Dust / Zoonosis / Land Use

Post by trader32176 »

Zoonotic Implications of Onchocerca Species on Human Health



The genus Onchocerca includes several species associated with ungulates as hosts, although some have been identified in canids, felids, and humans. Onchocerca species have a wide geographical distribution, and the disease they produce, onchocerciasis, is generally seen in adult individuals because of its large prepatency period. In recent years, Onchocerca species infecting animals have been found as subcutaneous nodules or invading the ocular tissues of humans; the species involved are O. lupi, O. dewittei japonica, O. jakutensis, O. gutturosa, and O. cervicalis. These findings generally involve immature adult female worms, with no evidence of being fertile. However, a few cases with fertile O. lupi, O. dewittei japonica, and O. jakutensis worms have been identified recently in humans. These are relevant because they indicate that the parasite's life cycle was completed in the new host-humans. In this work, we discuss the establishment of zoonotic Onchocerca infections in humans, and the possibility of these infections to produce symptoms similar to human onchocerciasis, such as dermatitis, ocular damage, and epilepsy. Zoonotic onchocerciasis is thought to be an emerging human parasitic disease, with the need to take measures such as One Health Strategies, in order to identify and control new cases in humans.

Onchocerciasis caused by Onchocerca lupi: an emerging zoonotic infection. Systematic review



Globalization has increased circulation of people, their food, livestock and pets in the world, and changes in the environment, climate and human behaviour have led to the rapid expansion of emerging infections throughout the world. One of the reasons of a new pathogen affecting humans is the passage from an animal to a human being. Onchocerca (O.) lupi, a filarial worm first described in a wolf in 1967, is an emerging pathogen which has been incriminated as the etiological agent for 205 canine, 2 feline and 18 human infections in Europe, Tunisia, Turkey, Iran and the USA. Most frequent findings in animals and humans are monolateral or asymmetrical variably painful subconjunctival swellings and nodules containing immature or mature worms affecting the eye and/or adjacent tissues accompanied by conjunctival hyperemia. Occasionally, subcutaneous nodules and masses affecting the spinal cord have been observed in humans. Diagnosis of O. lupi is achieved by microscopy of excised adult female worms which exhibit a particular cuticular structure and molecular analysis. Treatment consists in worm removal accompanied by antihelminthic, antibiotic and anti-inflammatory therapy.

Everything You Should Know About Onchocerciasis (River Blindness) ... lindness#1

What is onchocerciasis?

Onchocerciasis, also known as river blindness, is a disease that affects the skin and eyes. It’s caused by the worm Onchocerca volvulus.

Onchocerca volvulus is a parasite. It’s spread to humans and livestock through the bite of a type of blackfly from the genus Simulium. This type of blackfly is found near rivers and streams. That’s where the name “river blindness” comes from.

Read on to learn more about this condition.


There are different stages of onchocerciasis. In earlier stages, you may not have any symptoms. It can take up to a year for symptoms to appear and the infection to become apparent.

Once the infection becomes severe, symptoms may include:

skin rashes
extreme itching
bumps under the skin
loss of skin elasticity, which can make skin appear thin and brittle
itching of the eyes
changes to skin pigmentation
enlarged groin
light sensitivity
loss of vision

In rare cases, you may also have swollen lymph glands.


You can develop river blindness if you’re bitten repeatedly by infected female blackflies. The blackfly passes the larvae of the worm Onchocercidae through the bite. The larvae move to the subcutaneous tissue of your skin, and mature into adult worms over 6 to 12 months. The cycle repeats when a female blackfly bites a person infected with onchocerciasis and ingests the parasite.

Adult worms can live for 10 to 15 years and may produce millions of microfilariae during that time. Microfilariae are baby or larval worms. Symptoms appear when microfilariae die, so symptoms can continue to worsen the longer you are infected. The most extreme, longest-lasting cases result in blindness.

Risk factors

You’re at increased risk for onchocerciasis if you live near fast-running streams or rivers in intertropical areas. That’s because blackflies live and breed in these areas. Ninety percentTrusted Source of cases are in Africa, but cases have also been identified in Yemen and in six countries in Latin America. It’s unusual for casual travelers to contract the disease because repeated bites are necessary for the infection to be transmitted. Residents, volunteers, and missionaries in areas of Africa are at the greatest risk.
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