Podcast
Questions and Answers
What percentage of babies born with congenital CMV infection are symptomatic?
What percentage of babies born with congenital CMV infection are symptomatic?
Which of the following is NOT a tip for preventing CMV transmission?
Which of the following is NOT a tip for preventing CMV transmission?
Which condition is an outcome of symptomatic congenital CMV infection?
Which condition is an outcome of symptomatic congenital CMV infection?
Who would benefit the most from a CMV vaccine according to current priorities?
Who would benefit the most from a CMV vaccine according to current priorities?
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How do antiviral drugs for CMV primarily function?
How do antiviral drugs for CMV primarily function?
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What factor increases the risk of spillover between host species?
What factor increases the risk of spillover between host species?
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Which characteristic of pathogens allows them to infect a broad range of hosts?
Which characteristic of pathogens allows them to infect a broad range of hosts?
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Which environmental factor is NOT associated with the emergence and spread of infectious diseases?
Which environmental factor is NOT associated with the emergence and spread of infectious diseases?
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What unique trait of bats helps facilitate viral persistence for chronic infections?
What unique trait of bats helps facilitate viral persistence for chronic infections?
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How does genetic factors affect zoonotic transmissions?
How does genetic factors affect zoonotic transmissions?
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What is a significant consequence of human behaviors such as deforestation regarding zoonotic diseases?
What is a significant consequence of human behaviors such as deforestation regarding zoonotic diseases?
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What factor do specialist pathogens lack compared to generalist pathogens?
What factor do specialist pathogens lack compared to generalist pathogens?
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What role does the large population size of bats play in the ecology of disease?
What role does the large population size of bats play in the ecology of disease?
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What is the primary action of nucleoside analogues in the context of HBV infection?
What is the primary action of nucleoside analogues in the context of HBV infection?
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Which statement accurately reflects the relationship between HBV and liver cancer?
Which statement accurately reflects the relationship between HBV and liver cancer?
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What is a common feature of HPV infections?
What is a common feature of HPV infections?
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What distinguishes low-risk HPV from high-risk HPV?
What distinguishes low-risk HPV from high-risk HPV?
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Which of the following is true regarding the transmission of HPV?
Which of the following is true regarding the transmission of HPV?
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What allows the West Nile Virus to be transmitted to eggs?
What allows the West Nile Virus to be transmitted to eggs?
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Which of the following hosts is considered a dead end host for West Nile Virus?
Which of the following hosts is considered a dead end host for West Nile Virus?
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Which is a key step in the pathogenesis of West Nile Virus after infection from a mosquito?
Which is a key step in the pathogenesis of West Nile Virus after infection from a mosquito?
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Why is there no human vaccine for West Nile Virus despite having one for horses?
Why is there no human vaccine for West Nile Virus despite having one for horses?
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What form of herpesvirus DNA is maintained in the nucleus of an infected cell during latency?
What form of herpesvirus DNA is maintained in the nucleus of an infected cell during latency?
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Which of the following statements about herpesviruses is true?
Which of the following statements about herpesviruses is true?
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What is primarily expressed during the lytic cycle of herpesviruses?
What is primarily expressed during the lytic cycle of herpesviruses?
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Which is NOT associated with the reactivation of herpesviruses?
Which is NOT associated with the reactivation of herpesviruses?
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What role do mosquito dunks serve in managing West Nile Virus vectors?
What role do mosquito dunks serve in managing West Nile Virus vectors?
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How do birds contribute to the West Nile Virus transmission cycle?
How do birds contribute to the West Nile Virus transmission cycle?
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What is the CDC's recommendation regarding screening asymptomatic adolescents and adults for HSV infections?
What is the CDC's recommendation regarding screening asymptomatic adolescents and adults for HSV infections?
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Which group was primarily affected by Kaposi’s sarcoma before the AIDS epidemic?
Which group was primarily affected by Kaposi’s sarcoma before the AIDS epidemic?
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What was concluded about the relationship between Kaposi’s sarcoma and HIV?
What was concluded about the relationship between Kaposi’s sarcoma and HIV?
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What virus is identified as the cause of Kaposi’s sarcoma?
What virus is identified as the cause of Kaposi’s sarcoma?
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Which of the following cancers is NOT associated with Epstein Barr Virus (EBV)?
Which of the following cancers is NOT associated with Epstein Barr Virus (EBV)?
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During latency, which of the following proteins does EBV encode?
During latency, which of the following proteins does EBV encode?
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What is a significant challenge faced by herpesviruses like KSHV and EBV during latency?
What is a significant challenge faced by herpesviruses like KSHV and EBV during latency?
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What is the primary method for identifying KSHV?
What is the primary method for identifying KSHV?
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Study Notes
Ecological Habits of Animals
- Animal ecological habits heavily influence the spread of infectious diseases, specifically zoonotic diseases.
- There are several factors impacting the risk of spillover events:
- Human-host factors:
- Immunological factors: Immune system strength and response directly impact susceptibility to infection.
- Genetic factors: Genetic predispositions to certain diseases influence an individual's vulnerability.
- Behavioral factors: Practices like hunting, close contact with animals, and hygiene habits play a crucial role in disease transmission.
- Phylogenetic distance: The closer the relationship between the host species (in terms of evolution), the higher the risk of spillover.
- Pathogen characteristics:
- Generalist pathogens: These pathogens can infect a wide range of hosts, increasing the risk of jumping species barriers.
- Viral taxonomic groups: Different viral families have varying levels of zoonotic potential.
- Environmental resistance: The ability of the pathogen to survive in a specific environment influences its spread.
- Environmental factors:
- Loss of biodiversity: Habitat destruction can disrupt natural ecosystems and favor the emergence of infectious diseases.
- Land use change: Modifications to the environment can alter disease vectors and host populations.
- Global warming: Climate change can affect host behavior and pathogen survival, influencing disease transmission.
- Human-host factors:
Bats - A Unique Reservoir
- Bats harbor a diverse range of viral families, many of which don't seem to cause illness in the bats themselves.
- Bats are gregarious (live in groups), possess large population sizes, and have long lifespans. These factors aid in the survival and evolution of viruses.
- Frequent human-bat interactions, including bushmeat consumption, deforestation, and peridomestic habits, increase the potential for zoonotic transmission.
- Bats' longer lifespans relative to other mammals contribute to the potential for chronic viral infections.
Arbovirus Transmission
- Arboviruses are transmitted via arthropods, primarily mosquitoes.
- The virus persists in the vector, sometimes even being transmitted transovarially (through eggs), allowing for continuous transmission.
- Birds, rodents, and reptiles can act as reservoir hosts.
- Mammals, including humans, can be dead-end hosts, meaning they don't contribute significantly to the virus's spread.
West Nile Virus (WNV)
- WNV is a mosquito-borne virus that primarily infects birds.
- Mosquitoes act as vectors, transmitting the virus from birds to humans and horses through accidental biting.
- WNV was first discovered in the US in 1999 and has spread rapidly since then, coinciding with bird migration patterns.
- Infection progresses through the lymph nodes, spleen, and eventually crosses the blood-brain barrier, causing encephalitis.
- A vaccine for WNV is available for horses, but none exists for humans due to unpredictable outbreaks, economic factors, and challenges with clinical trials.
Managing West Nile Virus
- Vector management focuses on eliminating mosquito breeding grounds by monitoring and treating areas where adult mosquitoes lay eggs.
- Tracking mosquito populations and the viruses they carry is crucial for early detection and intervention.
- Mosquito dunks containing bacteria can be placed in water bodies to target larvae.
Herpesviruses - Evolutionary Legacy
- Herpesviruses emerged around 250 million years ago, during the time of the supercontinent Pangaea.
- They are complex viruses with large genomes and the ability to encode numerous proteins.
Herpesvirus Characteristics
- Herpesviruses are highly successful pathogens, well-adapted to their hosts.
- They often cause minimal or no symptoms and maintain high infection rates within their host populations.
- Herpesviruses establish lifelong infections, switching between two life cycles: latency and lytic phases.
- Latency: The virus is dormant with minimal viral expression.
- Lytic: The virus reactivates, producing virions and causing cell death.
The Latent Stage
- After the initial infection, herpesviruses remain latent in the host's cells.
- Viral DNA integrates into the host's genome, forming a circular structure called an episome.
- The latent stage can be interrupted by periods of lytic replication called reactivation, often triggered by various stimuli.
- Reactivation can be asymptomatic or cause clinical symptoms, but it primarily serves to maintain the viral reservoir in the host and potentially spread to new hosts.
Cytomegalovirus (CMV)
- CMV is a common virus, prevalent in about 1 in 150 babies born.
- While most infections are asymptomatic, symptomatic congenital CMV infections can cause significant health problems, including:
- Visual impairment
- Epilepsy
- Premature birth
- Coordination disorders
Preventing CMV
- Basic hygiene practices are critical:
- Don't share food utensils or drinks.
- Avoid close contact with saliva.
- Don't share toothbrushes.
- Wash hands regularly.
Antiviral Treatment
- Antiviral drugs can inhibit viral polymerase activity, reducing viral replication.
- They are primarily used in immunocompromised patients with active CMV replication.
- May improve outcomes for babies with congenital CMV infection.
- Can cause serious side effects.
CMV Vaccine Development
- A CMV vaccine is a high priority for research.
- Beneficial for women of childbearing age, transplant recipients, and toddlers.
- Vaccination of toddlers could indirectly protect women.
Herpes Simplex Virus (HSV)
- HSV-1 typically causes oral sores (cold sores) but can also cause genital herpes.
- HSV-2 primarily infects the genitals.
- HSV is associated with recurrent eye infections and, in rare cases, encephalitis.
HSV Transmission
- Transmitted through intimate person-to-person contact.
- Skin areas with HSV can infect mucous membranes.
Kaposi's Sarcoma (KS)
- Historically a rare disease but became more prevalent during the AIDS epidemic.
- KS is caused by the human herpesvirus 8 (HHV-8), also known as Kaposi's sarcoma-associated herpesvirus (KSHV).
- KSHV was discovered through DNA analysis of healthy tissue compared to DNA isolated from KS lesions.
- KSHV is related to Epstein-Barr virus (EBV).
EBV and KSHV - Cancer Associations
- Both viruses typically cause asymptomatic infections.
- EBV is associated with:
- Mononucleosis
- Burkitt lymphoma
- Nasopharyngeal carcinoma
- KSHV is associated with:
- Primary effusion lymphoma
- Kaposi's sarcoma
Latency in EBV and KSHV
- Both viruses establish latent infections.
- They infect dividing cells and need to attach their episomes to the host's DNA to maintain their presence during cell division.
- EBV encodes EBNA-1, and KSHV encodes LANA, proteins that help anchor their episomes.
Treatment and Prevention
- Nucleoside analogues: Drugs that inhibit viral polymerase activity, reducing viral replication.
- Hepatitis B (HBV) infection is a significant risk factor for liver cancer, which is a leading cause of cancer deaths worldwide.
- Liver transplantation is a standard treatment for HBV-related liver cancer, but viral reactivation in the graft can be a concern.
Human Papilloma Virus (HPV)
- Over 200 different papillomavirus types infect humans.
- Most HPV infections are asymptomatic and clear on their own.
- Persistent infections can cause genital or skin warts and contribute to various cancers, including cervical cancer, anal cancer, and throat cancers.
High and Low Risk HPV
- Low-risk HPV strains typically do not cause symptoms.
- High-risk HPV strains can lead to cervical dysplasia and specific cancer types.
- HPV is the most common sexually transmitted infection in the US.
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Description
Explore the intricate ecological habits of animals and their influence on the spread of infectious diseases, particularly zoonotic diseases. This quiz delves into factors affecting spillover events, including human-host interactions and pathogen characteristics.
