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The Democratic Republic of Congo officially declared on December 16, 2021 the end of the 13th outbreak of Ebola Virus Disease which had resurfaced on October 8, 2021, in Beni in North Kivu province. What is Ebola Virus Disease? What causes it? Let's find out.

Deadly viral fever

Ebola is a life-threatening disease caused by a virus belonging to the family Filoviridae The viral haemorrhagic fever was first identified in central Africa in 1976. The 2014-2016 outbreak in West Africa was the largest Ebola outbreak ever since the virus was discovered, leading to over 11,000 deaths. The disease was named after the Ebola River in Congo, formerly Zaire, where it was originally identified.

Ebola is a zoonotic disease, meaning it spreads from animals to humans. The virus which badly affects the immune system as it spreads through the body is transmitted to people from animals such as chimpanzees, gorillas, and monkeys. It is thought that fruit bats of the Pteropodidae family are natural Ebola virus hosts. It spreads among humans through contact with the bodily fluids (blood, faeces, urine, vomit, or semen) of infected people. Ebola is called a haemorrhagic fever virus as it causes problems with how our blood dots leading to internal bleeding.

What are the symptoms?

The main symptoms of Ebola Viral Disease include fever fatigue, sore throat severe headache, muscle and joint pain loss of appetite, vomiting, bleeding and diarrhoea. The virus can be detected in blood within a few days of the manifestation of symptoms. Immediate medical attention, early intervention with rehydration, and symptomatic treatment are said to improve chances of survival.

There are vaccines for protection against Ebola. These anti-Ebola jabs have been administered to help control the spread of Ebola outbreaks in Congo.

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People who have recovered from mild corona virus infections produce antibodies that target three different parts of the virus's spike protein that it uses to latch on to human cells

• A National Institutes of Health-funded study, published recently in the journal Science, offers the most detailed picture yet of the array of antibodies against SARS-CoV-2 found in people who've fully recovered from mild cases of corona virus.
• Most studies of natural antibodies that block corona virus have focussed on those that target a specific portion of the spike protein known as the receptor-binding domain (RBD). The RBD is the portion of the spike that attaches directly to human cells. As a result, antibodies explicitly targeting the RBD are an excellent place to begin searching for antibodies capable of fighting the virus.
• However, researchers at The University of Texas at Austin found that most antibodies target other portions of the spike protein than the RBD. The study led by Gregory Ippolito and Jason Lavinder, likens the spike protein to an umbrella, with the RBD at the tip of the "canopy." While some antibodies bind to the RBD, many others target the protein's canopy, known as the N-terminal domain (NTD).
• The team also found that about 40 % of antibodies target yet another portion of the spike called the S2 subunit. Additionally, the S2 subunit could make an ideal target for a possible pan-corona virus vaccine since fewer mutations exist at this portion of the spike.
• The study will prove helpful in designing vaccine booster shots or future vaccines tailored to fight coronavirus variants of concern.

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Memories of 2019 Sambhar tragedy came back to haunt Rajasthan as scores of birds were found dead on the lake. They included different species of birds such as rufous tree pie, owl, crow and gull. Earlier, a week before the bird deaths were reported from Sambhar, 189 demoiselle cranes had died at Jodhpurs Kaparda pond.

Bhopal-based National Institute of High-Security Animal Disease (NIHSAD) confirmed the cause of the bird deaths to be avian influenza (bird flu). The lab has detected two strains of influenza virus - H5N8 and H5N1-in the dead birds.

The H5N1 strain of bird flu can spread from birds to humans through contact. Symptoms of H5N1 include cough, fever, sore throat muscular pain, headache and difficulty breathing. The HSN1 strain can also result in human deaths.

Migratory birds were under observation in Jodhpur and other areas following these bird deaths Security was beefed up in the Desert National Park as well, which is home to the critically endangered Great Indian Bustard.

What happened in 2019?

In a similar incident in 2019, over 30,000 migratory birds died in Rajasthan, especially in the locality of Sambhar Lake. But the cause was found to be avian botulism. Avian botulism is a serious neuromuscular illness caused by a toxin produced by the bacterium clostridium botulinum. The outbreak at Sambhar was caused by various factors such as a good monsoon which created a favourable environment for the bacteria to thrive.

What is bird flu?

Bird flu is a highly infectious, respiratory disease in birds caused by the H5N1 influenza virus, which can occasionally infect humans and other animals that come into contact with a carrier. Bird flu usually affects poultry such as chicken and ducks. The other strain H5N8 is highly lethal among birds, but it has not been found to affect humans.

How does it spread?

Bird flu spreads when birds come into contact with nasal secretions and faeces of infected birds. It can spread to humans in a similar fashion.

Symptoms in birds

Lack of energy and appetite: swelling of the head, eyelids, combs; discolouration of legs: nasal discharge, coughing, sneezing and diarrhoea are symptoms observed in birds affected by avian flu. It is often fatal.

Symptoms in humans

If humans are affected by bird flu, they may show symptoms such as diarrhoea, high fever, chest pain, muscle pain, cough and headache.

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The perception that one's mobile is vibrating or ringing when it's not. It is characterised as a 'tactile hallucination' since the brain perceives a sensation that is not present. Psychologists say that detecting a vibrating/ring phone has become a habit, and the slightest muscle twitch or feeling of clothing moving could be misinterpreted by the brain.

Majority of cell phone users report experiencing phantom vibrations, with reported rates ranging from 27.4% to 89%.

"I think it's a little scary how dependent most of us have become on our devices," she said.

Smith said sometimes she suggests students go on a media "fast" and avoid using digital devices for a period of time.

"They'll typically report back, 'I couldn't go an hour,'" Smith said.

Phantom vibration syndrome isn't really harmful -- in the study of college students, more than 90 percent said they considered phantom vibrations to be ''only a little'' or ''not at all'' bothersome.

But some believe it's a warning sign that too much technology may be hazardous to human interaction. Smith says our attachment to devices becomes a serious problem when it keeps us from engaging with other people in the here and now.

"The remarkable prevalence of phantom vibration syndrome appears to reveal somethingabout our contemporary technological situation," writes Georgia Tech assistant professor Robert Rosenberger, Ph.D., in a recent analysis published in the journal Computers in Human Behavior. Habits, anxiety, brain chemistry and other factors may all contribute, and he says more study is needed to fully understand what's going on when we sense phone vibrations that aren't really there.

Credit : CBS News

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Hospitals in Haryana, Kerala, Punjab, Rajasthan, Tamil Nadu, Uttar Pradesh, Uttarakhand, Delhi, and Jammu and Kashmir are witnessing a surge in dengue cases with the number of cases reported exceeding one lakh. The Union health ministry has sent teams of experts to the nine States and Union Territories to support them in public health measures for control and management of the disease. What is dengue, what causes it, what are the symptoms to look out for, and how is it treated? Let's find out.

A mosquito-borne infection Dengue is a mosquito-borne viral infection that is transmitted to people through the bite of an infected Aedes aegypti mosquito. When a mosquito bites us, it not only sucks blood but also secretes saliva that enters our bloodstream. This is how an infected mosquito passes on the infection. Dengue is a seasonal disease which witnesses a surge in cases post-rain. Dengue virus causes fever and haemorrhagic symptoms.

Dengue infections are caused by four related viruses namely DEN-1, DEN-2, DEN-3, and DEN-4 belonging to the genus Flavivirus. These four viruses are called serotypes because each has different interactions with the antibodies in our blood serum. The four dengue virus serotypes mean it is possible to be infected more than once. In other words, being infected from one dengue virus does not guarantee protection from the other three. Once a person gets infected, he becomes the main carrier of the virus and passes it to uninfected mosquitoes. After recovery, he becomes immune to that particular serotype for lifetime.

Flying killers

Mosquitoes thrive in tropical regions. Dengue mosquitoes breed only in clear water. They lay eggs on the surface of the water which hatch in eight days (or even less in extremely warm weather).

Mosquitoes take refuge in dark spaces indoors and use puddles, tree holes, discarded vehicle tyres, and plant pots around homes to breed. If water is not allowed to stagnate, mosquitoes cannot multiply. Did you know that only female mosquitoes are capable of biting us? They feed on our blood to source protein for their eggs.

According to the World Health Organization, mosquito-borne diseases kill several million people worldwide, every year.

Dengue symptoms

Dengue causes a severe flu-like illness that may last up to a week. In some cases, the fever could be life-threatening, resulting in bleeding, a fall platelet count, and sometimes extremely low blood pressure. Dengue symptoms include high fever, severe headache, pain behind the eyes, nausea, vomiting, acute stomach ache, muscle and joint pain, and skin rash. They begin to manifest three to 14 days after the bite. The severity of the symptoms increases if the infection is not treated properly and in time. Seek medical advice immediately if you have a fever or develop any of the dengue symptoms.

At present, there are no vaccines for dengue or specific medications to treat it. Pain killers are prescribed for relief from symptoms. Drinking plenty of fluids and taking ample rest are also advised. So the best way to protect ourselves from dengue is to avoid mosquito bites by sleeping under the net using mosquito repellent, etc.

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An epizootic (from Greek epi for upon and zoon for animal) is a disease event in an animal population similar to an epidemic in humans. It may be restricted to a specific locale (outbreak), general (epizootic) or widespread (panzootic). Examples of epizootic disease include avian influenza, swine fever and foot and mouth disease.

Defining an epizootic can be subjective; it is based upon the number of new cases in a given animal population, during a given period, and must be judged to be a rate that substantially exceeds what is expected based on recent experience (i.e. a sharp elevation in the incidence rate). Because it is based on what is "expected" or thought normal, a few cases of a very rare disease (like a transmissible spongiform encephalopathy outbreak in a cervid population) might be classified as an "epizootic", while many cases of a common disease (like lymphocystis in esocids) would not.

Common diseases that occur at a constant but relatively high rate in the population are said to be "enzootic" (cf. the epidemiological meaning of "endemic" for human diseases). An example of an enzootic disease would be the influenza virus in some bird populations[1] or, at a lower incidence, the Type IVb strain of viral hemorrhagic septicemia in certain Atlantic fish populations.

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October 6, 2021, marks a historic day in humanity's fight against malaria, as the World Health Organization (WHO) approved the rollout of the malaria vaccine, RTS.S/AS01 (RTS.S) among children living in sub-Saharan Africa and other at-risk regions.

Malaria is a deadly infectious disease that claims more than 4 lakh lives every year around the world. It is caused by Plasmodium parasites that are transmitted to people through the bites of infected female Anopheles mosquitoes, called the malaria vector. Among the five parasite species that cause malaria in humans, Plasmodium falciparum and Plasmodium vivax pose the greatest threat.

Who will get the vaccines and how efficient is it in preventing the spread of malaria?

WHAT is RTS,S/AS01?

RTS,S/AS01 or Mosquirix (trade name) has been developed by British drug manufacturer GlaxoSmithKline in collaboration with Seattle-based health non-profit PATH and a network of African research centres, with partial funding from the Bill and Melinda Gates Foundation. The vaccine is the result of 30 years of research and it targets Plasmodium falciparum, the most common parasite causing malaria in Africa. The vaccine offers no protection against the other four species such as P vivax, P ovale, P knowlesi and P malariae which are prevalent in Southeast Asia, Americas and Europe.

RTS,S was created in 1987 by scientists working in GlaxoSmithKline laboratories. The European Medicines Agency issued a positive scientific opinion on the vaccine in July 2015, concluding that the benefits of the vaccine outweigh the risks

RTS.S has been rigorously tested through a series of clinical trials since 2019 in seven African countries (Burkina Faso, Gabon, Ghana, Kenya, Malawi, Mozambique, and Tanzania).

Who is it for?

The WHO has recommended that the RTS,S/AS01 malaria vaccine be used for the prevention of P. falciparum malaria in children living in regions with moderate to high transmission as defined by it. The vaccine has been recommended to be provided in a schedule of four doses in children from 5 months of age.

What is its efficacy?

The current approval of the vaccine is based on the results of the ongoing pilot programme in Ghana, Kenya and Malawi. More than 2.3 million doses of the vaccine have been administered in these countries so far as part of the pilot. The following observations have been made since:

• The vaccine offers 39% protection against malaria in children between the ages of five and 17 months.
• The vaccine prevents approximately 4 in 10 (39%) cases of malaria and about 3 in 10 (29%) cases of severe malaria.
• There is significant reductions in overall malaria admissions as well as malaria-induced anaemia.
• The vaccine also reduced the need for blood transfusions, which are required to treat life-threatening malaria anaemia by 29%.

How does the vaccine work?

RTS,S works by introducing the immune system to a fragment of a protein that is naturally present on the surface of Plasmodium parasite when it enters the bloodstream through an infected mosquito. The protein in the vaccine stimulates the production of antibodies, and allows the body to mount a swift response to the parasite the next time it is encountered. The vaccine is designed to prevent the parasite from infecting the liver, where it can mature, multiply, re-enter the bloodstream, and infect red blood cells, which can lead to disease symptoms.

Why is developing a vaccine against malaria tough?

Malaria vaccines have been in development since the 1960s, with substantial progress only in the last decade.

• Developing a vaccine against malaria parasite has been a difficult task, chiefly because of the parasite's complex lifecycle and genetical make-up. It has a multistage lifecycle occurring within two living beings, the vector mosquitoes and the vertebrate hosts (humans for instance). The survival and development of the parasite within the invertebrate and vertebrate hosts, in intracellular and extracellular environments, is made possible by more than 5,000 genes and their specialised proteins that help the parasite to invade and grow within multiple cell types and to evade host immune responses. The surface proteins and metabolic pathways keep changing during these different stages, that help the parasite to evade the immune clearance, while also creating problems for the development of drugs and vaccines.
• The technical complexity of developing any vaccine against a parasite is another obstacle.
• With no real market for a malaria vaccine in resource-rich countries like the U.S., pharmaceutical companies did not have a strong financial incentive to accelerate vaccine development. Hence there are a few malaria vaccine developers.

What are the symptoms and consequences of malaria?

Symptoms usually appear 10-15 days after the infective mosquito bite. According to the WHO, the first symptoms-fever, headache, and chills - may be mild and difficult to recognise as malaria. In no time, it can progress into severe illness and possible death.

Children may develop severe anaemia, respiratory distress or cerebral malaria, while adults can face multi-organ failure. Children under 5 years of age are the most vulnerable group affected by malaria.

Some facts about malaria

• There are more than 400 species of Anopheles mosquito, of which around 30 are malaria vectors. All the important vector species bite between dusk and dawn.
• Anopheles mosquitoes lay their eggs in water, usually shallow pools of fresh water, such as puddles, which are abundant during the rainy season in tropical countries. .
• Vector control is the main way to prevent and reduce malaria transmission. The two WHO-recommended methods are - insecticide-treated mosquito nets and indoor residual spraying. Early diagnosis and treatment of malaria reduces disease and prevents deaths.
• Exposure to malaria parasites does not confer lifelong protection.

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Micronutrients are one of the major groups of nutrients your body needs. They include vitamins and minerals.

Vitamins are necessary for energy production, immune function, blood clotting and other functions. Meanwhile, minerals play an important role in growth, bone health, fluid balance and several other processes.

Humans must obtain micronutrients from food since your body cannot produce vitamins and minerals — for the most part. That’s why they’re also referred to as essential nutrients.

Vitamins are organic compounds made by plants and animals which can be broken down by heat, acid or air. On the other hand, minerals are inorganic, exist in soil or water and cannot be broken down.

When you eat, you consume the vitamins that plants and animals created or the minerals they absorbed.

The micronutrient content of each food is different, so it’s best to eat a variety of foods to get enough vitamins and minerals.

Credit : Healthline

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Malnutrition refers to deficiencies or excesses in nutrient intake, imbalance of essential nutrients or impaired nutrient utilization. The double burden of malnutrition consists of both undernutrition and overweight and obesity, as well as diet-related noncommunicable diseases. Undernutrition manifests in four broad forms: wasting, stunting, underweight, and micronutrient deficiencies.

Wasting is defined as low weight-for-height. It often indicates recent and severe weight loss, although it can also persist for a long time. It usually occurs when a person has not had food of adequate quality and quantity and/or they have had frequent or prolonged illnesses. Wasting in children is associated with a higher risk of death if not treated properly. Stunting is defined as low height-for-age. It is the result of chronic or recurrent undernutrition, usually associated with poverty, poor maternal health and nutrition, frequent illness and/or inappropriate feeding and care in early life. Stunting prevents children from reaching their physical and cognitive potential. Underweight is defined as low weight-for-age. A child who is underweight may be stunted, wasted or both.

Micronutrient deficiencies are a lack of vitamins and minerals that are essential for body functions such as producing enzymes, hormones and other substances needed for growth and development.

Credit : WHO

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Kerala was on high alert after a 12-year-old boy died of the deadly Nipah virus in Kozhikode, early this month. The State ramped up efforts to stop a potential outbreak, as health officials began to trace contacts and isolate hundreds of people who came into contact with the boy.

The virus has an estimated fatality rate of between 40% and 75%, according to the World Health Organisation (WHO), making it deadlier than the coronavirus.

The state dealt with Nipah in 2018, when more than a dozen people died from the virus. This time around, the concern is compounded by the fact that the state has grabbed national headlines in recent weeks for seeing the highest number of daily COVID-19 cases across India.

Nipah is a rare viral infection. Infected patients show symptoms of fever and respiratory problems in the early stages that quickly advance to fatal encephalitis (inflammation of the brain). Fruit bats or flying foxes of the Pteropodidae family are the natural host of the Nipah virus.

The WHO has listed Nipah as among the 10 priority pathogens requiring urgent research. The organisation takes into consideration the virus' ability to trigger lethal outbreaks and the non-availability of drugs against it.

What is Nipah?

Nipah is a zoonotic disease (zoonotic is a disease transmitted to humans from animals), spread by bats, pigs and infected people, according to the WHO. Outbreaks have been reported in Southeast Asia since 1998, when the virus was first identified in Malaysia. The 1998-99 outbreak spread from pigs to humans in Malaysia. It caused severe respiratory illness in pigs and encephalitic disease in humans. It killed 100 people and affected thousands of pigs. The Nipah virus has a mortality rate of 75%, according to the WHO.

How does it spread?

Fruit bats, the natural host of the Nipah virus, show no signs of infection. However, the virus spreads through the bats saliva or excreta. Humans and animals such as pigs become infected through contact or ingestion of materials contaminated with saliva or urine of such bats. In 2004, in Bangladesh, humans became infected after consuming date palm sap that had been contaminated by infected fruit bats. Humans also get affected when they come in contact with infected pigs or when they consume the meat of the animal. Human-to-human transmission happens through body fluids, including nasal or respiratory droplets, urine, or blood. Such transmission was recorded in Siliguri, West Bengal, in 2001, and in the 2018 outbreak in Kerala. In Siliguri, 75% of cases occurred among hospital staff or visitors.

What are the symptoms?

Symptoms typically present one to two weeks after exposure to the virus. Initial symptoms are flu-like. They include fever, headache, respiratory problems and muscle pain. This may be followed by neurological signs such as disorientation and dizziness. In severe cases, the infection can cause encephalitis, which is the inflammation of the brain, and eventually death. Survivors can have long-term neurological issues such as a seizure disorder or personality changes, according to the WHO.

What can be done to diagnose it?

According to the U.S. Centers for Disease Control and Prevention (CDC), during the early stages of the illness, laboratory testing can be conducted using real-time polymerase chain reaction (RT-PCR) from throat and nasal swabs, cerebrospinal fluid, urine, and blood. Later in the course of illness and after recovery, testing for antibodies is conducted using an enzyme-linked immunosorbent assay (ELISA).

What is the treatment?

There are no drugs or vaccine available against Nipah. The primary treatment is supportive care. Rest, hydration, and treatment of symptoms are advised. Individuals infected need to be hospitalised and isolated to avoid spread of disease to others. Identifying potential victims, testing them and treating them as early as possible are the way forward.

What should you do to protect yourself from Nipah?

• Avoid exposure to animals such as bats and pigs.
• Avoid eating fruits bitten by bats or that may have been contaminated by them.
• Avoid contact with infected people.
• Maintain personal hygiene. Practise handwashing regularly with soap and water.
• Consume only well-cooked, home-made food.
• Spread awareness among your friends and family members.

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Dr. Soumya Swaminathan, the chief scientist at the World Health Organization, recently said that India seems to be "entering some stage of endemicity". What does that mean?

According to the US Centers for Disease Control and Prevention (CDC), in the endemic stage "the disease will remain dormant in a particular region or country. If the conditions become favourable it flares up and spreads among people." Common flu and malaria are examples of endemic stage diseases.

Endemicity simply means that the spread of the disease has started to slow down and there may not be widespread cases. The disease transmission continues and people still get infected, but not at a level that causes public health concern. However, localised peaks can be expected in some areas.

The complete endemic stage of any disease can be reached only when a large section of the population becomes immune to a disease either through vaccination or through antibodies acquired from a prior infection. India has a long way to go before reaching that stage. So, it is important to stay cautious and continue to wear masks, sanitise hands and avoid crowded places.

In February 2021, a study published in the Nature journal indicated that the SARS-CoV-2 virus is set to, become endemic and would continue to circulate in pockets of the global population. The Nature survey shows many scientists expect the virus that causes COVID-19 to pose less danger over time. This means, the virus is here to stay and we have to learn to live with it.

Did you know?

• An epidemic is a disease that affects a large number of people within a community, population, or region.
• A pandemic is an epidemic that's spread over multiple countries or continents.
• An outbreak is a sudden increase in the number of endemic cases.

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Do you know what's common among SARS-CoV-2, HIV AIDS, Ebola, SARS, MERS, Nipah, H1N1 flu (swine flu) and H5N1 flu (bird flu)? Yes, all of these are zoonoses, that is, they are animal-bome diseases.

A zoonosis is any disease or infection that is naturally transmissible from vertebrate animals to humans. Zoonoses have different modes of transmission. In direct zoonosis, the disease is transmitted from animals to humans through air, bites or saliva. In indirect zoonoses, the transmission occurs via an intermediate species (referred to as a vector), which carries the disease pathogen. These pathogens can be viruses, bacteria, fungi or parasites.

Though the world has seen the emergence of diseases throughout history, in the last 50 years, a host of new infectious diseases has spread rapidly after making the evolutionary jump from animals to humans. According to the World Health Organisation (WHO), 70% of emerging human pathogens come from animals. In the last century, at least 10 infectious diseases jumped from animals to humans, it says.

What has led to this?

Globalisation, deforestation, encroachment of wild environments, human-animal conflicts and wildlife trade have led to the spike in zoonosis outbreak, says a report by the WHO, released in September 2019. It has also warned that the risk of a global pandemic is growing and that zoonotic diseases will continue to emerge and re-emerge.

The deadly ones

As the world grapples with the new coronavirus, which is thought to have spread from bats, let's take a look at some of the major zoonotic diseases and their outbreaks...

Bubonic plague

Bubonic plague was the cause of the Black Death that swept through Asia, Europe and Africa in the 14th Century and killed an estimated 50 million people. It took centuries for some societies to recover. Plague is a bacterial disease caused by Yersinia pestis. It is carried by rodents and cats. The infection in humans is caused by the bite of an infected flea.

HIV-AIDS

HIV, the virus that causes AIDS, originated from chimps and other primates and is thought to have first infected humans at least a century ago. However, it was first recognised only in 1981. By the end of that year, there were 270 reported cases and 121 deaths. HIV destroys the immune system, opening the door to a host of deadly infections. The virus has now mutated to a separate human-only disease. Between 1981 and 2018, the disease caused an estimated 32 million deaths worldwide.

SARS An epidemic of SARS, caused by a strain of coronavirus SARSCOV, affected 26 countries and resulted in more than 8,000 cases in 2003.

SARS-CoV is thought to have spread from bats, which, in tumn, spread to other animals (civet cats) and perhaps first infected humans in southern China in 2002.

Ebola

The 2014-2016 outbreak in West Africa was the largest Ebola outbreak since the virus was first discovered in 1976. The outbreak started in Guinea and then spread to other parts of the continent. The virus is transmitted to people from wild animals (such as chimpanzees, gorillas, monkeys, antelopes or porcupines). Human-to-human transmission happens through direct or indirect contact with the blood or bodily fluids of infected people. It is thought that fruit bats of the Pteropodidae family are natural Ebola virus hosts.

Nipah

Nipah virus (Niv) infection severely affects both animals and humans. The natural host of the virus are fruit bats. It can spread from bats to other animals to people or directly from bat to and between people. Even eating a fruit bitten by an infected bat can transfer Nipah to humans. The disease was first identified in 1998 during an outbreak in Malaysia, India has reported three NiV outbreaks in the past. The first two were in West Bengal: Siliguri in 2001 and Nadia in 2007. The third outbreak occurred in Kerala in May 2018.

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Fleas are tiny bugs. They don’t grow much larger than the tip of a pen, and they range from light brown to almost black in color. They don’t have wings, so they get around by jumping from place to place. Their thin, flat bodies and hard shells mean you often need to squeeze them between fingernails or two hard surfaces to kill them. Even then, where there is one, many often follow. Fleas reproduce quickly, especially if you have pets in the house. But even if you don’t have pets, your yard can potentially play host to fleas, and you may end up with a bunch of mysterious bites. They’re almost impossible to get rid of without a pesticide treatment.

Fleabites are pretty distinctive. They look like small, red bumps in clusters of three or four or a straight line. The bumps remain small, unlike mosquito bites. You might notice a red “halo” around the bite center. The most common places to find these bites are around the legs or ankles. Fleabites are also common around the waist, armpits, breasts, groin, or in the folds of the elbows and knees.

For humans, the risk of contracting another disease from the flea is very small. Yet bacteria can get into your body through the bite and cause an infection, especially if you scratch it. An infected bite will turn red, warm, and it may release pus. Fleabites can also cause an allergic reaction in people who are sensitive to them. Symptoms can range from raised welts on the skin to difficulty breathing. Fleabites can also cause complications in pets, such as allergic reactions and even anemia from blood loss. That’s why it’s important to take animals to a vet if they have fleas.

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A person can get it by eating food or drink contaminated with human or animal feces where the parasite is present.

Many parasitic worms enter their hosts by active invasion. Their transmission success is often based on a mass production of invasive stages. However, most stages show a highly specific host-finding behaviour. Information on host-finding mechanisms is available mainly for trematode miracidia and cercariae and for nematode hookworms. The larvae find and recognise their hosts, in some cases even with species specificity, via complex sequences of behavioural patterns with which they successively respond to various environmental and host cues. There is often a surprisingly high diversity of host-recognition strategies. Each parasite species finds and enters its host using a different series of cues. For example, different species of schistosomes enter the human skin using different recognition sequences. The various recognition strategies may reflect adaptations to distinct ecological conditions of transmission. Another question is how, after invasion, parasitic worms find their complex paths through their host's tissues to their often very specific microhabitats. Recent data show that the migrating parasite stages can follow local chemical gradients of skin and blood compounds, but their long-distance navigation within the host body still remains puzzling. The high complexity, specificity and diversity of host-recognition strategies suggest that host finding and host recognition are important determinants in the evolution of parasite life cycles.

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Amebiasis is a parasitic infection of the intestines caused by the protozoan Entamoeba histolytica, or E. histolytica. The symptoms of amebiasis include loose stool, abdominal cramping, and stomach pain. However, most people with amebiasis won’t experience significant symptoms.

The cause of amebiasis is infection by the protozoan parasite Entamoeba histolytica. It begins when a person drinks contaminated water or eats foods contaminated with the cystic form (infective stage), comes in contact with contaminated colonic irrigation devices or the fecally contaminated hands of food handlers, or by oral-anal sexual practices.

The cystic form changes into trophozoites (invasive form) in the ilium or colon and invade the mucosal barrier, leading to tissue destruction and diarrhea. These trophozoites can reach the portal blood circulation to the liver and eventually go to other organs. It only infects humans, and the CDC does not classify it as a free-living organism.

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