Introduction to clinical virology:
The basics of virology, the world's 6 deadliest viruses explained thoroughly, and how vaccines and treatments work.
About
Hello, everyone! Before you start learning a lot of valuble information about clinical virology, allow me to introduce the roots of my passion. My passion for clinical virology started back in 2020 when the coronavirus first appeared. I noticed how its effect on our lives quickly escalated from simply being an element of our lives, to completely taking over. I noticed how people would contract the virus and just have to hope that they do not put too much stress on their bodies. I saw how all we could do was put a mask in front of our faces and wait for this pandemic to come to an end. This was our life until January 2021 when two bright minds developed the first COVID-19 vaccine. This was our first sign of hope. That’s when I realized that I wanted to be that person who researches intense viruses, thoroughly understands them and then can develop a highly successful vaccine for them. Right then, I knew that I wanted to be a clinical virologist. Because of this, I created this website to introduce the future generation to the basics of clinical virology. I want to explain what the study is, how viruses are discovered, how vaccines are developed, and what makes a virus fatal. I also explained the symptoms, diagnosis process and possible treatments of the 6 deadliest viruses known to man. I want this website to be my first step in becoming a clinical virologist and achieving my long-term goal of curing HIV.
The Basics of Clinical Virology
What is clinical virology?
Clinical virology is a field of study related to microbiology and pathology. It entails the study of viruses and virus-like agents as well as their classification, genomes, disease-producing properties, and treatments such as vaccines and biocontainment. Clinical virology is by far one of the most quickly developing fields of medical research the profession is extremely pertinent.
How are viruses identified?
Even though many viruses are discovered because of a random appearance of a new disease, an example of this being HIV/AIDS back in 1980, or even a more recent disease like SARS in 2003, virologists can now identify a virus by studying the DNA and RNA sequences on the antigen that get incorporated into human cells. This allows viruses that don’t necessarily cause diseases to be detected.
How are vaccines developed?
Vaccines need to be grown from whole parts of viruses. They viruses are then deactivates and injected into a person to trigger the immune response to the virus. First, the white blood cells interpret the antigen as either self or foreign. If it is foreign, the immune system begins to fight. The white blood cells which get involved are called B-lymphocytes and they produce antibodies which neutralize the virus. Afterwards, most B- lymphocytes die, but some become B-memory cells which memorize the antigen and can stop the infection early on preventing another contraction of the virus.
What makes a virus fatal?
What makes a virus fatal can be multiple reasons such as:
Haemorrhaging which leads to death.
If respiratory organs are affected then the body cannot respire.
If the white blood cells are having trouble reaching the infection.
If there is no antiviral therapy such as a vaccine or a medication, then, the virus’ symptoms will eventually kill a person.
If a person loses fluids, then their metabolism cannot work on minerals. This leads to death.
What is the pertinence of this study today?
This field of study shows extreme pertinence today due to how desperately the world needed them these past few years. We have been going through the coronavirus pandemic and were unable to start medically preventing it until January 2021 when a vaccine was first developed. This pandemic is not our first and it will certainly not be our last. Therefore, we need to emerge the future generation into the study to help us control future pandemics with minimal damage.
Marburg Virus
The Marburg virus is the causing agent of Marburg virus disease. The virus is a member of the filovirus family, much like Ebola, and is categorized by the homorganic fever that it causes. It has up to an 88% fatality rate, but fatality rates can be as low as 24% depending on the severity of the case.
The virus first appeared in 1967 in Marburg and Frankfurt, Germany as well as Belgrade, Serbia. This outbreak was associated with experiments with African green monkeys imported from Uganda.
The Marburg virus is transmitted through direct human contact with secretions, surfaces, bodily fluids, and blood. Infected people usually die by bleeding into the gastrointestinal tract and skin, shock, disseminated intravascular coagulation, and multiorgan failure.
Symptoms (2-21 days):
- Fever.
- Headache.
- Severe malaise.
- Muscle aches.
- Diarrhea.
- Abdominal cramps and pain.
- Nausea and vomiting.
- Rash (2-7 days).
- Hemorrhagic manifestations (5-7 days).
- Blood in feces and vomit.
- Bleeding nose, gums, and vagina.
- Nervous system issues.
- Blood loss and shock (8-9 days).
Diagnosis:
Diagnosis of this virus is particularly difficult due to the samples being a biohazard risk. Containment of the specimens need to be intense with triple packaging when being sent out to labs, especially if the specimen isn’t deactivated.
The following tests are used for diagnosis as declared by the WHO:
Electron microscopy.
Antigen-capture detection tests.
Antibody-capture enzyme-linked immunosorbent assay (elisa).
Reverse transcriptase polymerase chain reaction (rt-pcr) assay.
Serum neutralization test.
Virus isolation by cell culture.
Treatments:
There are no approved antiviral therapies or vaccines for the Marburg virus. However, treating the symptoms and rehydration increase survival rate. There are also antiviral therapies under development.
Marburg virus infection chart:
("Marburg Virus Disease")
(Rees)
("Ghana Declares Outbreak Of Marburg Virus, A Deadly And Contagious Disease Like Ebola, Which Officials Are Trying To Contain")
The Ebola virus is a part of the filovirus family. It is the virus associated with Ebola virus disease- a deadly disease most prominent in Africa with a fatality rate of around 50%. The disease’s cause is a group of viruses with the Ebola virus genus causing an infection. These viruses are:
Ebola virus (Zaire ebolavirus)
Sudan virus (Sudan ebolavirus)
Taï Forest virus (Taï Forest ebolavirus)
Bundibugyo virus (Bundibugyo ebolavirus)
Reston virus (Reston ebolavirus)
Bombali virus (Bombali ebolavirus)
Of these Ebola virus genera, only (Ebola, Sudan, Taï Forest, and Bundibugyo viruses) are known to cause diseases in people.
Ebola virus was discovered in 1976 in the Democratic Republic of the Congo. Where the virus came from is still a mystery to scientists, but they believe that it is animal-borne with bats or nonhuman primates. The virus is transmitted through blood, tissue, and bodily fluid. Then, the virus gets through skin barriers, mucous membranes, eyes, mouths, or noses.
Symptoms:
- Fever.
- Sore throat.
- Muscle and joint pain.
- Weakness.
- Fatigue.
- Loss of appetite.
- Abdominal pain, diarrhea, and vomiting.
- Hemorrhaging and bleeding.
- Red eyes, hiccups, and rashes (late-stage).
Preventions:
Do not make contact with the bodily fluids of those who are sick or recently recovered from Ebola virus disease.
Avoid touching any surfaces touched by a sick person.
Avoid making contact with the blood and other fluids of bats and nonhuman primates.
Treatments and recovery:
The treatments for Ebola are known as therapeutics and there are 2 approved ones: Inmazeb, which was approved in October of 2020, which is a combination of 3 monoclonal antibodies; and Ebanga, which was approved in December of 2020, which is a single monoclonal antibody. A monoclonal antibody is a much like a regular antibody in the sense that stops a virus from replicating, but these proteins are synthesized in a lab, and they bind to the glycoprotein- part of the Ebola virus- and they keep it from entering the cells. These treatments have only been evaluated by the FDA for the genus Zaire ebolavirus.
Some other ways to improve survival rate such as giving fluids and electrolytes, medications for vomiting and diarrhea, medications for fever, pain killers, and treating infections if they come up.
Ebola vaccine:
The FDA approved the Ebola vaccine on December 19th, 2019, and it protects recipients against the Zaire ebolavirus, which is the deadliest. Another vaccine was developed in 2019 after the Ebola virus outbreak in the Democratic Republic of the Congo. It is a two-dose vaccine with different vaccines for each dose.
Ebola Virus
("Ebolavirus | Virus Genus")
(Häggström)
Hantavirus
Hantaviruses are a genus of around 14 viruses coming from the Bunyaviridae family. It was first discovered in South Korea in 1978. This virus has rodents as a vector; so, it is classified as a zoonotic virus. Each hantavirus serotype has its own specific rodent vector. This disease is transmitted from the rodent to the person when particles of droppings, saliva, or urine get incorporated into the air which infect the person after they breathe it.
A group of hantaviruses appeared in the United States in 1993 mainly in southern states like Arizona and New Mexico. These viruses caused hantavirus pulmonary syndrome, a fatal lung disease.
Symptoms (last 42-56 days):
- Fever
- Gastrointestinal (stomach and intestinal) issues
- Myalgia (muscle pain)
- Hypotension (low blood pressure)
- Respiratory issues
- Fatigue
- Headaches
- Nausea and vomiting
- Diarrhea.
Diagnosis:
Blood tests are done where they look for IgM antibodies for any hantavirus serotypes indicating an infection which the immune system has started to fight against by making these antibodies through the b-lymphocytes.
Prevention:
- Avoid rodents
- Avoid mouse droppings
- Wear gloves if you are around rodents
Treatments and Vaccines:
There is no specific treatment. Treatment is given for the symptoms which can last 3 days to three months but mortality rate is still at 38% (CDC, 2022)
(CDC, 2022)
(Gavi, 2021)
Japanese Encephalitis Virus
Japanese encephalitis virus is a viral brain infection with a vector of mosquitos. It is most commonly found in Southeast Asia and the Pacific Islands which puts over 3 billion people at risk. Mosquitos transfer the virus transfer the virus from birds and pigs to people by first biting an infected bird or pig and then biting a human. Infected patients need to be hospitalized and given fluids and oxygen so the symptoms can be handled.
Symptoms:
- Most people are asymptotic. But 1 in 250 infected people develop serious symptoms. (NHS, 2019)
- Symptoms happen 5 to 15 days after contracting the virus and can be mistaken for the flu
- Symptoms include tremors, fevers, still neck, speech problems, muscle weakness, muscle paralysis, confusion
- A third of patients with severe symptoms die (NHS, 2019)
- It takes several months to recover from severe symptoms; however, half of those who recover have brain damage (NHS, 2019), also they may have tremors, weakness, learning issues, paralysis.
Diagnosis:
- Conducting a spinal tap to detect the virus-specific IgM antibodies which appear between 3 and 8 days after infection.
Prevention:
- Get vaccinated before visiting area where the virus exists (vaccine protects 9 out of 10 people) (NHS, 2019)
- Avoid mosquito bites.
Treatment:
- There is no specific treatment or antiviral medication has been developed yet.
- Hospitalization and observation are required.
- Doctors treat the symptoms with rest, fluid and pain medications.
- Mortality rate is still at 30%.
(Cosmos, 2022)
Areas with most Japanese Encephalitis Virus outbreaks
(“Japanese encephalitis virus infection, diagnosis and control in domestic animals”, 2017)
Lassa fever is a zoonotic virus-casing illness with the African rat as a vector. It was first discovered in Lassa, Nigeria in 1969 but spread throughout Sierra Leone, Liberia, Guinea, and other West African countries. The virus is commonly transmitted by exposure to the urine of an infected African rate or by inhaling air that has been contaminated with rodent secretions; however, human-to-human transmissions are possible.
Symptoms: (1-3 weeks after infection):
Around 80% of infections’ symptoms are undiagnosed because of how mild they are. Some mild symptoms are:
- A headache.
- Fever.
- Weakness.
More severe cases (around 20%) have symptoms like:
- Hemorrhagic fever.
- Hemorrhaging in gums, nose, and eyes.
- Vomiting.
- Respiratory distress.
- Chest and back pain.
- Facial swelling.
- Abdominal pain
Neurological issues like hearing loss (1/3 of infections), encephalitis, and tremors are possible as a result of this infection.
If a pregnant woman gets infected during her third trimester, then the fetus has a 95% chance of dying. 15-20% of hospitalized patients die, usually due to vascular collapse.
Diagnosis:
Diagnosis is through enzyme-linked immunosorbent serologic assays. These check for IgG and IgM antibodies which are made by the B-lymphocytes after the virus has been detected by the immune system. The tests also check for the Lassa antigen.
Treatment:
- If given soon enough an antiviral drug called Ribavirin can help.
- Hyperimmune serum, which can be collected from survivors of Lassa fever virus, has worked in the past.
- Patients must also maintain a healthy blood pressure, electrolyte balance, hydration, and decent oxygen levels.
- No vaccine exists yet.
Prevention:
Avoiding contact with Mastomys rodents, a common vector, especially in regions like west Africa.
Lassa Fever Virus
Number of Lassa Fever Virus infections and deaths in Nigeria in 2021
(Infection pattern, case fatality rate and spread of Lassa virus in Nigeria, 2021)
(CDC, 2022)
Rabies Virus
Rabies is a fatal yet preventable disease that can be contracted by a human or animal if they have been bitten or scratched by a rabid animal. It is 100% fatal if left untreated. It can be found in over 150 countries and territories, but it causes the most deaths in Asia and Africa.
There are 2 forms of the disease: furious rabies and paralytic rabies.
- Furious rabies causes temperamental behavior, hyperactivity, and hydrophobia. Cardiorespiratory arrest occurs a few days later which kills the patient.
- Paralytic rabies is what 20% of humans get infected with. The patient would slowly start to get paralyzed, and the paralysis would spread form the wound site. Next, would come a coma, then, death.
Symptoms:
- Fever.
- Tingling.
- Pain.
- Paresthesia at wound.
If the virus makes its way to the central nervous system, the brain and spinal cord would become fatally inflamed.
Rabies is most commonly found in wild animals including bats, skunks, raccoons, and foxes- this is the case mainly in the United States. However, some countries have rabid dogs as well, which actually cause most of the deaths.
Transmission:
Rabies is transmitted through direct contact with an infected person or animal. This can be through mucous membranes, tissue, saliva, or broken skin.
Diagnosis:
Virus isolation can be used to test saliva. Also, spinal fluid and serum are used to check for the antibodies for rabies made by the B-lymphocytes once the antigen is detected by the immune system of either the animal or the human. The rabies antigen is tested for in nerves at the base of hair follicles on skin biopsy specimens.
Treatment:
- Immediately after being bitten by a rabid animal, rabies shots can be curative.
- Also, after any form of contact with a rabid animal, one must wash out the wound with soap and water, to avoid long exposure to the mucous membrane and saliva.
- Other than that, there is no effective treatment.
Prevention:
- A rabies vaccines is given to babies during the first week of their life in doses of two.
- Vaccinating pets.
- Protecting pets from wild animals.
- Keeping bats out of the house.
Rabies virus structure, 2019
Effect of Rabies on the human body
(Rabies Lyssavirus)