Issuu

newsletter #1:

presented by Biology Club 2023-2024

Yellow Fever transmission methods .................................... P.3 regions they are prevalent in ....................... P.7 prevention and treatment ............................. P.7 Malaria transmission methods .................................... P.9 regions they are prevalent in ...................... P.11 prevention and treatment ............................ P.12 Ebola transmission methods .................................. P.13 regions they are prevalent in ..................... P.14 prevention and treatment ............................ P.15

YELLOW FEVER transmission methods by 4G (05) Chu Yan Ching (Stephanie)

Yellow fever is an acute viral haemorrhagic disease that is transmitted through mosquitoes. There are over 200 thousand cases of yellow fever per year globally, leading to a 30 thousand death toll per year. Countries in Africa and Latin America have the highest risk of yellow fever outbreaks. Transmission methods Yellow fever is caused by an arbovirus transmitted to humans by the bites of infected Aedes and Haemagogus mosquitoes. Mosquitoes acquire the virus by feeding on infected primates and then transmit the virus to other primates. Primates infected with the yellow fever virus are infectious to mosquitoes shortly before the onset of fever and up to 5 days after onset. Transmission cycles The different mosquito species live in different habitats, including domestic, wild and semi-domestic environments. Thus, there are three types of transmission cycles. Jungle (or sylvatic) yellow fever consists of mosquitoes biting non-human primates such as tropical rainforest monkeys and spreading the disease among them, while also occasionally to humans working or travelling in the jungle.

YELLOW FEVER transmission methods (cont.) In intermediate (or savannah) yellow fever, the most common type of outbreak in Africa, mosquitoes living in both the wild and domestic areas infect both monkeys and people, leading to outbreaks in many separate villages simultaneously. Urban yellow fever causes large epidemics when infected people introduce the virus into heavily populated urban settings where there are high density of certain mosquito types and people with no immunity. Symptoms The majority of individuals infected with the yellow fever virus do not develop symptoms, but when symptoms do occur, they typically manifest in two stages: the acute phase and the toxic phase. Acute Phase Symptoms: 1. Fever 6. Nausea, vomiting, and loss of appetite 2. Backache 7. Sensitivity to light (photophobia) 3. Muscle aches 8. Red eyes, face, and tongue 4. Fatigue 9. Headache (often located behind the eyes) 5. Dizziness

YELLOW FEVER transmission methods (cont.) Following a brief period of improvement in symptoms, approximately 15% of individuals progress to the toxic phase, which can be lethal. Toxic Phase Symptoms: Persistent high fever Jaundice: yellowing of the skin and eyes Abdominal pain and tenderness Decreased urine output Bleeding (blood in the vomit, black stools, or bleeding from the nose and gums) Delirium, seizures, and in severe cases, coma

YELLOW FEVER transmission methods (cont.) by 4H (10) Lei Sydney

Diagnosis 1. Medical history and physical examination: The doctor will ask about your symptoms, recent travel history, and potential exposure to mosquitoes in endemic areas. They will also perform a physical examination to look for signs of yellow fever, such as jaundice, fever, headache, muscle pain, and nausea. 2. Blood tests Enzyme-linked immunosorbent assay (ELISA): detecting antibodies produced by the immune system in response to the yellow fever virus Polymerase chain reaction (PCR): detecting the genetic material (RNA) of the yellow fever virus in your blood Serology: measuring the levels of specific antibodies in your blood Rising levels of IgM antibodies indicate recent or acute infection Presence of IgG antibodies suggests past infection or vaccination

Colombia Per

YELLOW FEVER regions they are prevalent in by 4H (10) Lei Sydney

Regions at risk Sub-Saharan Africa South America Brazil (Amazon rainforest regions) Colombia Peru

prevention and treatment by 4H (10) Lei Sydney

Treatment There is no specific antiviral treatment for yellow fever. Most patients require only supportive care, which includes rest, adequate hydration, and management of symptoms such as fever, pain and nausea. Severe cases may require hospitalization. In the hospital, patients receive close monitoring of vital signs, intravenous fluids to maintain hydration, and treatment for any complications that may arise.

YELLOW FEVER prevention and treatment (cont.) Prevention 1. Vaccination The vaccine provides long-lasting immunity to the body. The most widely used vaccines are YF-VAX and Stamaril. 2. Vector control To reduce mosquito populations and their breeding sites. Eliminating stagnant water sources where mosquitoes lay their eggs (e.g. standing water in containers, tires, and flowerpots) The use of insecticides 3. Mosquito bite prevention Use insect repellents containing DEET, picaridin, or oil of lemon eucalyptus on exposed skin Wear long-sleeved shirts, long pants, and socks to cover exposed areas of the body Use bed nets treated with insecticide while sleeping in areas with a high risks of yellow fever transmission

EBOLA transmission methods by 3G (12) Soo Pak Hei (Cyrus)

Transmission methods According to World Health Organization (2023), Ebola virus disease (EVD or Ebola) is a rare but severe illness in humans. It is often fatal. People get infected with Ebola by touching: Infected animals when preparing, cooking or eating them Body fluids of an infected person such as saliva, urine, faeces or semen Things that have the body fluids of an infected person like clothes or sheets Ebola enters the body through cuts in the skin or when touching one’s eyes, nose or mouth. Early symptoms include fever, fatigue and headache. Some types of Ebola can be prevented with vaccines and treated with medicines.

EBOLA transmission methods (cont.) Transmission Cycle The transmission of the Ebola virus involves bats, specifically Pteropodid bats, which are frugivorous and roost in large groups. These bats consume fruits, crushing the pulp, ingesting the juices, and expelling the fibrous pulp, accompanied with urine and feces sometimes. Fruit falling to the ground, potentially coated in bat saliva and urine/feces, creates a "fruit rain" that can transmit the virus to other frugivores foraging on the ground. Close physical contact between bats in social groups and the exchange of saliva also contribute to the virus spreading. Ebola is an RNA virus with a limited infectious lifespan, but the high water content of fruits and humid forest floor conditions may extend its survival and increase the chance of infecting new hosts. Further experiments are needed to validate the "fruit rain" hypothesis and determine the virus's lifespan under proposed conditions.

EBOLA regions they are prevalent in by 4A (3) Cho Joshua Chi Ho

Ebola mainly occurs in regions in third-world countries, in particular in Africa. The first cases of Ebola were detected in Sudan and Zaire (now the Democratic Republic of Congo) in 1976. Since then cases have been recorded in places like Gabon, Guinea, Liberia, Republic of the Congo, Sierra Leone, Sudan and Uganda. In Africa, imported cases have also been found in Mali, Nigeria, Senegal and South Africa. The largest outbreak occurred from 2014-2016 in West Africa, resulting in a death toll of 11325, with more than 28600 people infected. Since then, minor outbreaks have occurred each year in African countries, resulting in lower death tolls due to the advancement in medical treatment and medicine.

EBOLA prevention and treatment by 5G (3) Chu Ka Hin (Henry)

Treatment As with most viral diseases, there is no direct treatment for most Ebola viruses, although the Zaire strain can be treated directly. Treatment is generally separated into two intentions: 1. Direct treatment: Only for patients infected with the Ebola Zaire strain Aims to stop the propagation of the virus directly The most popular method is monoclonal antibodies Monoclonal antibodies: Antibodies that are synthesised in laboratories Working principle: Binding to glycoproteins on the surface of the Ebola virus to prevent it from entering body cells The drugs Inmazeb™ and Ebanga™ are the only two treatments approved by the United States Food and Drug Administration (FDA) Both drugs were noted to result in much higher survival for patients in drug trials

EBOLA transmission methods (cont.) 2. Supportive care: Used across all Ebola strains Aims to repair or stem the damage done by an Ebola infection Considering how haemorrhaging and loss of fluids are major reasons of death from Ebola, supportive care can be very effective Methods include: Oral or intravenous fluids: Replace fluids lost from Ebola symptoms Blood transfusions: Replace blood loss from Ebolainduced haemorrhages Medicine for pain/nausea/diarrhoea: Managing associated symptoms Medicine for infections: Reduces risk for opportunistic infections Considering how haemorrhaging and loss of fluids are major reasons for death from Ebola, supportive care can be very effective

EBOLA transmission methods (cont.) Prevention Never catching a disease is generally better than catching it and recovering, especially when it comes to Ebola. Therefore, prevention efforts have always been the main focus of Ebola control. Like treatment, two types of personal prevention are available: 1. Vaccination: Once again is only available for the Ebola Zaire strain Three vaccines approved by three major regulatory entities rVSV-ZEBOV: Approved by the United States Food and Drug Administration and the European Medicines Agency, recommended by the World Health Organisation. It is the most widely approved vaccine available. Ad26.ZEBOV and MVA-BN-Filo: A 2-dose vaccination approved by the European Medicines Agency, also recommended by the World Health Organisation. Ad5-EBOV: A vaccine approved by the China Food and Drug Administration. The vaccines do not contain live virus, meaning that it is not possible to be infected directly via vaccination. Live viruses are not used, meaning that there is no chance of infection via vaccination. rVSV-ZEBOV is recommended for adults above the age of eighteen, whilst the combination Ad26.ZEBOV and MVA-BN-Filo are recommended for anyone above the age of one. 2. Personal prevention: Lessens contact with the virus in the first place

MALARIA transmission methods by 3A (23) Lee Yat Yin Beatrice

Malaria is an infectious disease that is transmitted by infected mosquitoes. The bite of an infected Anopheles mosquito transmits a parasite that enters the victim’s blood stream and travels into the person’s liver where the parasite reproduces. The parasite, called plasmodium, causes a high fever that involves shaking chills and pain. In the worst cases malaria leads to coma and death. Malaria was traditionally treated by chloroquine or quinine, but with declining success due to drug resistance. By the late 1960s, efforts to eradicate Malaria had failed and the disease was on the rise. Fortunately, artemisinin extracted from Qinghao by the Chinese woman Youyou Tu, a 2015 Nobel Laureate in Physiology and Medicine, represents a new class of antimalarial agents that rapidly kill the Malaria parasites at an early stage of their development. Since 2000, 12 countries have been certified malaria-free by the World Health Organization, including China in 2021. In order to eliminate malaria globally, Bill & Melinda Gates Foundation has increased funding to partners in China to support further research and development regarding malaria treatment and prevention --- by lowering the cost of existing antimalarial drugs so they become more affordable to low-income countries, and accelerating the launch of novel medicines to tackle the drug resistance challenge.

MALARIA regions they are prevalent in by 5H (13) Lo Man Yi Kristen

Malaria thrives where the culprit of the disease, the female Anopheles mosquito, thrives. This would be the tropical areas, where it is warm and humid enough for these mosquitoes to survive to later become carriers of the disease, as well as for malaria parasites to be able to complete their growth cycle in order to be infectious to humans. This particularly holds true for Plasmodium falciparum, one of the deadliest malaria-causing parasites, which cannot complete its growth cycle at temperatures below 20°C (68°F), and hence cannot be transmitted to humans.

Around the globe, Malaria is most prevalent in African countries, home to about 95% of all malaria cases and 96% of deaths in 2021. Four African countries accounted for more than half of all malaria deaths worldwide in 2022, namely Nigeria (31.3%), the Democratic Republic of the Congo (12.6%), United Republic of Tanzania (4.1%) and Niger (3.9%). Another factor contributing to widespread Malaria in these regions is the feeding habits of the Anopheles species. The predominant malaria vectors found in Africa, An. gambiae and An. funestus, are strongly anthropophilic, meaning preferring to feed on humans, greatly increases the transmission of malaria in humans.

MALARIA prevention and treatment by 5H (13) Lo Man Yi Kristen

Despite having plagued the world for thousands of years, advancements in science and technology have facilitated the discovery of treatment methods to end the long reign of malaria. Malaria must be treated with prescription drugs, usually in pill form, to kill the parasite. The type of drug and the length of treatment vary, depending on the type of parasite and its resistance to medicine, the weight and age of the patient and whether or not they are pregnant.

Among the various types of antimalarial drugs, the most effective medicine would be Artemisinin-based combination therapies (ACTs), which utilizes a combination of an artemisinin derivative, the key component responsible for killing the malaria parasite, and the partner drug that helps prevent the development of resistance. When a patient takes ACT, the artemisinin component quickly enters the bloodstream and is rapidly absorbed by the malaria parasites present in the body. It undergoes chemical reactions and is converted into its active form, which generates free radicals (highly reactive molecules) within the parasite's cells. The free radicals produced by the activated artemisinin damage proteins essential for the survival and reproduction of the malaria parasite, leading to the parasite's death.

MALARIA prevention and treatment (cont.) An alternative to ACT is Chloroquine phosphate, and is the preferred treatment for any parasite that is sensitive to the drug. Yet, one of its biggest limitations is that many parasites have grown resistant to chloroquine, and the drug is no longer an effective treatment. Prevention is key to the defense against Malaria. A direct prevention method would be avoiding mosquito bites, such as by using mosquito nets and repellents, and wearing protective clothing in places where malaria is prevalent. Medicine could also be taken as a preventative measure when travelling to high-risk areas, notably chemoprophylaxis drugs that should be taken during and after the stay for maximum effect. New advancements in vaccines and preventive chemotherapies also have shown success in reducing the infection rate among vulnerable groups.