Welcome to Biology Notes Online! We are the BNO Team, dedicated to providing high-quality, accessible biology study notes for students and teachers alike. Our goal is to simplify complex biological concepts and present them in an easy-to-understand format, entirely free of charge. Whether you're preparing for exams, teaching a class, or simply passionate about biology, our comprehensive notes are designed to support your learning and teaching journey.
SARS-CoV-2 is the virus that causes COVID-19. COVID-19 is a highly infectious respiratory illness that can spread from person to person through respiratory droplets or close contact. The virus was first identified in Wuhan, China in December 2019 and has since spread to become a global pandemic. Symptoms of COVID-19 can range from mild to … Read more
Astrovirus is a type of virus that can cause gastroenteritis (also known as stomach flu) in humans. The virus is highly contagious and is primarily spread through close contact with infected individuals or through contaminated food or water. Symptoms of astrovirus infection may include diarrhea, vomiting, abdominal pain, and fever. Most people recover from an … Read more
Crimean-Congo Hemorrhagic Fever (CCHF) is a viral disease that is transmitted to humans by ticks. It is a highly infectious and severe disease that can be fatal in up to 50% of cases. The virus is found in many parts of the world, including Africa, Asia, and Europe. CCHF is caused by a virus in … Read more
Lassa virus is an RNA virus that is spread to humans through contact with the urine or feces of an infected Mastomys rat. It is a type of virus known as an arenavirus, and it is endemic in West Africa. The virus is named after the town of Lassa, in Borno State, Nigeria, where it … Read more
Through the bite of an infected Aedes species mosquito (Ae. aegypti or Ae. albopictus), dengue viruses are transmitted to people. These mosquitoes can transmit other viruses including Zika and chikungunya. 4 billion people, or close to half of the world’s population, reside in dengue-risk zones. In risky locations, dengue is frequently the main cause of … Read more
Hepatitis C is a viral infection that causes liver inflammation, sometimes leading to serious liver damage. The hepatitis C virus (HCV) is spread through contaminated blood, and it can be acute or chronic. Acute hepatitis C is a short-term illness that occurs within the first 6 months after someone is exposed to the virus. Chronic … Read more
Hepatitis A is a liver inflammation brought on by the hepatitis A virus (HAV). Primarily, the virus is transmitted when an uninfected (and unvaccinated) individual consumes food or water contaminated with the faeces of an infected individual. The disease is strongly linked to unclean water or food, inadequate sanitation, poor personal hygiene, and oral-anogenital contact. … Read more
Hepatitis B is a viral infection that causes liver inflammation, sometimes leading to serious liver damage. The hepatitis B virus (HBV) is transmitted through contact with the blood or other body fluids of an infected person. This can occur through sexual contact, sharing needles, or from an infected mother to her baby at birth. Symptoms … Read more
Hepatitis D, commonly referred to as “delta hepatitis,” is a viral infection of the liver (HDV). Hepatitis D is only transmitted to individuals who are simultaneously infected with the hepatitis B virus. Hepatitis D is transmitted when blood or other body fluids from an infected individual enter the body of an uninfected person. Hepatitis D … Read more
Rabies is a viral disease that causes inflammation of the brain in humans and other mammals. It is transmitted through the saliva of infected animals, usually through a bite. The virus attacks the central nervous system, leading to symptoms such as fever, muscle spasms, and hallucinations. If left untreated, rabies is almost always fatal. It … Read more
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