Dengue fever

Dengue fever

• Dengue fever, also known as breakbone fever, is a mosquito-borne infection that causes a severe flu-like illness. There are four different viruses that can cause dengue fever, all of which spread by a certain type of mosquito. 
• Dengue can vary from mild to severe; the more severe forms include dengue shock syndrome and dengue hemorrhagic fever (DHF). 
• Patients who develop the more serious forms of dengue fever usually need to be hospitalized. 

• There are currently no vaccines for Dengue fever. 
• The best way to prevent the disease is to avoid being bitten by mosquitoes altogether. Although there is no certain treatment for Dengue, it can be treated as long as it is caught before developing into dengue shock syndrome or dengue hemorrhagic fever. 

What are the signs and symptoms of Dengue Fever?

A symptom is something the patient feels or reports, while a sign is something that other people, including the doctor detects. A headache may be an example of a symptom, while a rash may be an example of a sign. 

Mild Dengue Fever - symptoms can appear up to seven days after the mosquito carrying the virus bites, and usually disappear after a week. This form of the disease hardly ever results in serious or fatal complications. The symptoms of mild dengue fever are:

·         Aching muscles and joints

·         Body rash that can disappear and then reappear

·         High fever

·         Intense headache

·         Pain behind the eyes

·         Vomiting and feeling nauseous

Dengue hemorrhagic fever (DHF) - symptoms during onset may be mild, but gradually worsen after a number of days. DHF can result in death if not treated in time. Mild dengue fever symptoms may occur in DHF, as well as the ones listed below:

·         Bleeding from your mouth/gums

·         Nosebleeds

·         Clammy skin

·         Considerably damaged lymph and blood vessels

·         Internal bleeding, which can result in black vomit and feces (stools)

·         Lower number of platelets in blood - these are the cells that help clot your blood

·         Sensitive stomach

·         Small blood spots under your skin

·         Weak pulse

Dengue shock syndrome - This is the worst form of dengue which can also result in death, again mild dengue fever symptoms may appear, but others likely to appear are:

·         Intense stomach pain

·         Disorientation

·         Sudden hypotension (fast drop in blood pressure)

·         Heavy bleeding

·         Regular vomiting

·         Blood vessels leaking fluid

·         Death

What are the Causes of Dengue?

There are four Dengue viruses (DENV) that cause Dengue fever, all of which are spread by a species of mosquito known as the Aedes aegypti mosquito, and more rarely by the Aedes albopictus mosquito. Aedes aegypti originated in Africa, but nowadays is found in all the tropical areas around the world and prospers in and close to areas of human population. 


The virus is transmitted from an infected mosquito to human. The process begins when a person who is infected with the Dengue virus is bitten by a mosquito, the virus is then passed on when someone else is then bitten by the infected mosquito. 

If you have suffered from dengue fever previously it is still possible to contract it again, because of the number of different types of viruses that cause the fever. If you were infected again and became ill, there is a greater risk of developing a harsher form of the disease, such as dengue hemorrhagic fever (particularly in children). This is unusual because, normally, previous exposure to a virus causes the body to carry antibodies that allow the body to fight off the virus more easily the second time.

What are the Complications of Dengue?

The majority of people suffering from dengue fever get better within 2 weeks. However, some individuals can suffer fatigue and depression for months after the infection. Dengue fever can develop to harsher forms of the disease i.e. Dengue hemorrhagic fever and Dengue shock syndrome.

Diagnosis of Dengue fever

The signs symptoms of Dengue fever are similar to some other diseases, such as typhoid fever or malaria, which can sometimes complicate the chances of a prompt and accurate diagnosis. In order for a doctor to properly diagnose dengue fever they will:

·         Assess the symptoms - the doctor will take into account all your symptoms to properly diagnose whether you have dengue. Some tests may be ordered to determine whether it is a dengue infection, or some other.

·         Blood sample - this sample can be tested in a laboratory in a number of ways to find signs of the dengue virus. If the dengue virus is detected diagnosis is straightforward; if this fails there are other blood tests which can identify antibodies, antigens and nucleic acids, including: 

o    -ELISA (enzyme-linked immunosorbent assay)

o    -HI assay (hemagglutination inhibition assay)

o    -RT-PCR (reverse transcriptase-polymerase chain reaction)

·         Assess your medical history - The doctor will need to know your travel history and medical history, especially if it involves mosquito exposure.

What are the treatment options for dengue fever?

Because dengue is a virus there is no specific treatment or cure, however there are things the patient or the doctor can do to help, depending on the severity of the disease. 

For milder forms of dengue the treatment methods are:

·         Prevent dehydration - high fever and vomiting can dehydrate the body. Make sure you drink clean (ideally bottled) water rather than tap water. Rehydration salts can also help replace fluids and minerals.

·         Painkillers - this can help lower fever and ease pain. As some NSAIDs (non-steroidal anti-inflammatory drugs), such as aspirin or ibuprofen can increase the risk of internal bleeding, patients are advised to use Tylenol (paracetamol) instead.

The following treatment options are designed for the more severe forms of dengue fever:

·         Intravenous fluid supplementation (IV drip) - in some harsher cases of dengue the patient is unable to take fluids orally (via the mouth) and will need to receive an IV drip.

·         Bloood transfusion - a blood transfusion may be recommended for patients with severe dehydration.

·         Hospital care - it is important that you be treated by medical professionals, this way you can be properly monitored (e.g. fluid levels, blood pressure) in case your symptoms worsen. If the patient is cared for by physicians and nurses experienced with the effects and complications of hemorrhagic fever, lives can be saved.

Prevention of dengue fever

At present there is no dengue vaccine; one is currently in development. Even so, developing a vaccine to protect against four closely related viruses that can cause the disease will not be easy. 

The best method of prevention is to avoid being bitten by mosquitoes. If you live or travel to an area where dengue exists, there a number of ways to avoid being bitten:

·         Clothing - your chances of being bitten are significantly reduced if you expose as little skin as possible. When in an area with mosquitoes, be sure to wear long trousers/pants, long sleeved shirts, and socks. For further protection, tuck your pant legs into your shoes or socks. Wear a hat.

·         Mosquito repellants - be sure to use one with at least 10% concentration of DEET, you will need a higher concentration the longer you need the protection, avoid using DEET on young children.

·         Use mosquito traps and nets - studies have shown that the risk of being bitten by mosquitoes is considerably reduced if you use a mosquito net when you go to sleep. Untreated nets are significantly less effective because the mosquito can bite the host through the net if the person is standing next to it. Also, even tiny holes in the netting are usually enough for the mosquito to find a way in. Nets that have been treated with insecticide are much more protective. Not only does the insecticide kill the mosquito and other insects, it is also a repellent - fewer mosquitoes are likely to enter the room(s).

·         Smell - Avoid wearing heavily scented soaps and perfumes.

·         Windows - use structural barriers, such as window screens or netting.

·         Camping - if you are camping, treat clothes, shoes and camping gear with permethrin. There are clothes which have been treated with permethrin.

·         Certain times of day - try to avoid being outside at dawn, dusk and early evening.

·         Stagnant water - the Aedes mosquito prefers to breed in clean, stagnant water. It is important to frequently check and remove stagnant water in your home/premises. 

o    Turn pails (buckets) and watering cans over; store them under shelter so water cannot accumulate in them.

o    Remove the water from plant pot plates. To remove mosquito eggs, clean and scrub them thoroughly. Ideally, do not use plant pot plates.

o    Loosen soil from potted plants. This will prevent puddles from developing on the surface of hard soil.

o    Make sure scupper drains are not blocked; do not place potted plants and other objects over the scupper drains.

o    Gully traps that are rarely used should be covered; replace gully traps with non-perforated ones, and install anti-mosquito valves.

o    Do not place receptacles under or on top of any air-conditioning unit.

o    Flower vases - change the water every other day. When you do so, scrub the inside of the vase thoroughly and rinse it out.

o    Leaves - make sure leaves are not blocking anything which may result in the accumulation of puddles or stagnant water.

Mosquitoes and its Life Cycle

Mosquitoes and its Life Cycle

What is Mosquitoes and its Life Cycle?

• Mosquitoes belong to the group of insects known as diptera, or flies.
• In fact, mosquito means “little fly” in Spanish.
• Diptera means “two wings” – the characteristic that distinguishes flies from other types of insects.
• What distinguishes a mosquito from other types of flies are its proboscis and the hair-like scales on its body.
• The female mosquito’s life is often measured in weeks or months.
• Males typically live only about a week.
• Mosquitoes hatch from eggs laid in places that are or will be filled with water.
• The eggs hatch into worm-like larvae that usually lie just beneath the water’s surface, breathe through tubes on the tail end of their bodies, and feed on microscopic organisms, such as bacteria.
• Thus most mosquito larvae require water containing organic material, such as leaves or sewage to serve as food for microorganisms that will be consumed by the developing mosquito larvae.
• In less than a week, hatchling larvae can grow and develop into comma-shaped pupae.
• While larvae are commonly called “wigglers” because they wiggle violently when disturbed, mosquito pupae are known as “tumblers”  because they tumble through the water when disturbed.
• While mosquito larvae and pupae breathe through siphon-like devices, the pupal stage does not feed.
• Usually within three days the pupa will transform into an adult mosquito.
• There are some notable exceptions to the standard mosquito life cycle.
• The larvae of some mosquito species eat the larvae of other species, though the predatory larvae of some species will develop into blood-feeding adults.
• Female mosquitoes can be particular about whose blood they consume, with each species having its own preferences.
• Most mosquitoes attack birds and mammals, though some feed on the blood of reptiles and amphibians.
• Only female mosquitoes bite, because a blood meal is usually required for egg laying.
• All male mosquitoes, and the females of a few species, do not bite. They feed on nectar and other plant juices instead of blood.
• Mosquitoes can fly long distances; some more than 20 miles from the water source that produced them.
• But they don’t fly fast, only about 4 miles an hour.
• And because they typically fly into the wind to help detect host odors, fewer mosquitoes are about on windy days.
• As a mosquito flies closer to its target, it looks for the movement of dark objects. Once it finds you, it lands, inserts its proboscis and probes for blood vessels beneath the skin.
• When it finds one, it injects saliva into the wound.
• The saliva contains an anticoagulant that ensures a steady, smooth flow of blood. Unfortunately, the mosquito’s saliva also may contain pathogens such as malaria parasites or encephalitis virus.

CULEX MOSQUITOES

• The West Nile virus is transmitted predominantly by Culex mosquitoes.
• Culex are medium-sized mosquitoes that are brown with whitish markings on the abdomen.
• These include the house mosquitoes that develop in urban areas, and the western encephalitis mosquito more commonly found in rural areas.
• They typically bite at dusk and after dark. By day they rest in and around structures and vegetation.
• Culex lay “rafts” of eggs on still water in a variety of natural and man-made containers, including tree holes, ditches, sewage and septic system water, catch basins (storm drains), non-chlorinated swimming and wading pools, decorative ponds, bird baths, flower pots, buckets, clogged gutters, abandoned tires, and water-retaining junk and debris of all sorts.
• They cannot develop in running water and water that is present less than a week. Therefore, every effort should be made to prevent water from accumulating in containers or, at least, empty water out of them on a weekly basis.
• Adult Culex mosquitoes do not fly far from where they develop as larvae.
• And unlike other mosquitoes that die with the coming of the first hard frost in autumn, the house mosquito can “over-winter” in protected places like sewers, crawlspaces and basements.

AEDES MOSQUITOES

• The Aedes group of mosquitoes includes many nuisance mosquitoes, as well as species that transmit disease to humans.
• This is a diverse group that includes the inland floodwater mosquito (Aedes vexans), the Asian tiger mosquito (Aedes albopictus) and the tree hole mosquito (Ochlerotatus triseriatus*) – all of which prefer to feed on the blood of mammals.
• Floodwater mosquitoes lay their eggs on soil that becomes flooded, allowing the eggs to hatch and larvae to develop in temporary pools.
•  Asian tiger and tree hole mosquitoes are container-breeding mosquitoes, laying their eggs in small, water-filled cavities, including tree holes, stumps, logs, and artificial containers, such as discarded tires.
• They are often the first mosquito noticed in spring, and later after heavy rainfall.
• Adults emerging together from flooded areas are often so numerous that natural controls, such as predators and parasites, are overwhelmed.
• Unlike some other Aedes mosquitoes, inland floodwater mosquitoes may fly more than 10 miles from their larval development sites in search of blood meals.

MOSQUITO-BORNE ENCEPHALITIS DISEASES

• The cycles of mosquito-borne viral encephalitis and meningitis diseases are similar.
• Most involve various bird species that are said to bereservoirs.
• Once infected by a mosquito bite, the reservoir species are usually not seriously affected.
• They will, at least for a time, produce enough virus in their bodies to infect mosquitoes. 
• In this manner, mosquitoes pick up the virus and may become vectors, or organisms that transmit the disease to other animals, such as birds, horses or humans.
• Horses and humans are generally thought of as “dead-end” hosts because they do not produce enough virus to infect mosquitoes.
• Thus, dead-end hosts are not involved in the spread of disease.
• nfall and temperature.

EASTERN and WESTERN EQUINE ENCEPHALITIDES

• Outbreaks of these related encephalitis viruses are rare.
• Several different mosquito species are suspected vectors of Eastern equine encephalitis, while Culex tarsalis, known as the western encephalitis mosquito, is the vector of Western equine encephalitis.
• Their uncommon occurrence is fortunate because, of all encephalitides, the equine encephalitides may have the highest potential for human mortality.

PREVENTING MOSQUITO BITES

• One strategy to prevent mosquito bites is avoidance.
• But even if one were to remain indoors throughout the mosquito season, they might still encounter mosquitoes.
• Mosquitoes, such as the house mosquito, are adept at getting into structures to feed on the inhabitants, and also to use crawlspaces, basements and cellars as quiet spots in which to shelter themselves for the winter.
• It is important to keep structures in good repair, maintaining the integrity of window and door screens and weather stripping, and screening or sealing all gaps through which mosquitoes might enter, such as spaces around utility lines, vents, foundation cracks, and gaps around windows and doors.
• Repellents are the first line of defense against mosquito bites. Many products provide some degree of protection against mosquito bites

MANAGING MOSQUITOES

• Historically the most effective mosquito control has been larviciding, which is the application of pesticides formulated to kill mosquito larvae before they become biting adults.
•  The Illinois Department of Public Health promotes mosquito control by advising and funding local health departments and other organizations that conduct larviciding, as well as mosquito surveillance.
• Surveillance includes the collection and identification of mosquitoes that helps predict mosquito and disease outbreaks and the focusing of control efforts in problem locations.

LARVICIDING

• Larvicides containing the insect growth regulator, methoprene, work by disrupting the larva’s metamorphosis, preventing it from developing into an adult.
• The toxicity of both types of larvicide is quite low, and both are considered safe to use in waters containing fish.
• These larvicides can be purchased at discount and hardware stores, and lawn and garden centers for private individuals to use on their property. 

DISEASES CAUSED BY VIRUSES

• A virus is a microscopic parasite that depends on living cells for its survival. 
• Once viruses gain entry to the body, they start destroying healthy cells by consuming the nutrients in them. 
• Viruses also use healthy cells as their breeding grounds. 
• This usually leads to health issues and diseases, which can trivial or fatal in nature.

Chickenpox

• Chickenpox is a highly contagious disease. 
• Four million children in America per year became infected with the chickenpox virus before the chickenpox vaccine became available, according to the Mayo Clinic. 
• Signs are a red rash and small blisters, or pox, that eventually break open. 
• These rashes are often accompanied by fever, headache, cough and loss of appetite. The pox normally develop on the face, chest, scalp and back. 
• After infection, virus can be transmitted to another person within 48 hours.

Influenza

• Flu is a respiratory disease, mainly caused by the influenza virus. 
• According to the New York State Department of Health, 5 to 20 percent of the population is diagnosed with flu annually. 
• Influenza symptoms include high fever, headache, sore throat and muscle aches. Diarrhea, nausea and vomiting may also occur. 
• Respiratory droplets that are released into air by infected people coughing and sneezing spreads the virus to healthy people.

Hemorrhagic Fever

• Viruses belonging to four different categories cause viral hemorrhagic fever (VHF). Early symptoms are muscle aches and fever. 
• However, as the virus progresses, it often causes internal and external bleeding, because VHF affects the vascular system of the body. 
• These viruses make the blood vessels porous, which can lead to minor or massive bleeding. 
• Patients bleed under the skin, internally, or even from the eyes or mouth with this affliction. 
• VHF affects internal organs, particularly the liver, lungs and kidneys. 
• It is often fatal.

Meningitis

• The fluid that surrounds the brain and spinal cord, cerebro-spinal fluid (CSF), becomes affected by the virus that causes meningitis. 
• The meninges protects the spinal cord, brain and the CSF. 
• Enteroviruses affect the CSF, causing headaches, high fever and stiffness in the neck. Other symptoms include nausea, sleepiness and vomiting. 
• In many cases, meningitis is caught by being in contact with an infected person.

Common Cold

• The common cold is a viral infection caused by a virus that affects the upper respiratory tract. 
• It usually manifests as a runny nose, cough, constant sneezing or sore throat. 
• Common cold viruses usually enter the body through the nose or mouth. The cold is a harmless infection, and recovery takes one or two weeks.

Viral Diseases

Viral Diseases

What are viral diseases?

Viral diseases are extremely widespread infections caused by viruses, a type of microorganism.

There are many types of viruses that cause a wide variety of viral diseases. The most common type of viral disease is the common cold, which is caused by a viral infection of the upper respiratory tract (nose and throat).

Other common viral diseases include:

• ·         Chickenpox
• ·         Flu (influenza)
• ·         Herpes
• ·         Human immunodeficiency virus (HIV/AIDS)
• ·         Human papillomavirus (HPV)
• ·         Infectious mononucleosis
• ·         Mumps, measles and rubella
• ·         Shingles
• ·         Viral gastroenteritis (stomach flu)
• ·         Viral hepatitis
• ·         Viral meningitis
• ·         Viral pneumonia

1. Viral diseases are contagious and spread from person to person when a virus enters the body and begins to multiply. Common ways that viruses spread from person to person include:
2. Breathing in air-borne droplets contaminated with a virus
3.  Eating food or drinking water contaminated with a virus
4. Having sexual contact with a person who is infected with a sexually transmitted virus
5.  Indirect transmission from person to person by a virus host, such as a mosquito, tick, or field mouse
6. Touching surfaces or body fluids contaminated with a virus 

• Viral diseases are not treatable with antibiotics, which can only cure bacterial diseases and infections. However, the most common viral diseases, the common cold and the flu, are self-limiting in generally healthy people. 
• This means that the viral infection causes illness for a period of time, then it resolves and symptoms disappear as your immune system attacks the virus and your body recovers.

SYMPTOMS

What are the symptoms of viral diseases?

Symptoms of viral diseases vary depending on the specific type of virus causing infection, the area of the body that is infected, the age and health history of the patient, and other factors. The symptoms of viral diseases can affect almost any area of the body or body system. Symptoms of viral diseases can include

What causes viral diseases?

Viral infections occur when a virus enters the body and invades the inside of the body’s cells in order to reproduce. If the body’s immune system is unable to fight off the virus, it multiplies and spreads to other cells, repeating the process and leading to a widespread infection

How are viral diseases treated?

Treatment of viral infections varies depending on the specific virus and other factors. General treatment measures are aimed at relieving your symptoms so that you can get the rest you need to keep up your strength and recover without developing complications.

General treatments for viral infections include:

·         Acetaminophen (Tylenol) or ibuprofen (Motrin, Advil) for fever, body aches, and pain

·         Drinking extra fluids

·         Getting extra rest and sleep

·         Maintaining good nutrition

Depending on the type of viral infection and the presence of complications, a wide variety of other treatments may be needed. For example, a human papillomavirus (HPV) infection that leads to cervical dysplasia can be treated by surgical removal of the abnormal cells on a woman’s cervix.   

In general, it is recommended that children younger than age six not use cold or cough medications because of the risk for serious side effects. In addition, people with a viral disease should not use aspirin or products that contain aspirin because of the risk of developing a rare but life-threatening condition called Reye syndrome. Reye syndrome has been linked to taking aspirin during a viral illness, such as a cold or the flu.

Complementary treatments

Complementary and traditional treatments will not cure a viral disease but may help to increase comfort, promote rest, and minimize symptoms of viral diseases. Some possible treatments include:

·         Chicken soup to help break up congestion and provide easy-to-digest nutrients and extra fluids to help keep up strength

·         Supplements or products that contain vitamin C, echinacea, or zinc

·         Using a vaporizer

·         Using mentholated ointments on the chest

What are the possible complications of viral diseases?

In some people, viral diseases can break down the body’s defenses and lead to more serious infections and life-threatening complications. Therefore, it is important to visit your health care provider when you have symptoms of a viral infection. Once the underlying infection has been determined, following the treatment plan outlined by your health care provider can help reduce any potential complications including:

·         Acute bronchitis

·         Cervical cancer (from human papillomavirus infection)

·         Dehydration

·         Frequent life-threatening, opportunistic infections

·         Otitis media (ear infection)

·         Pneumonia

·         Secondary bacterial infection

·         Seizures

·         Shock and coma

·         Sinusitis

·         Worsening of asthma