FAQs
Mosquitoes and Mosquito Control
Q. What is a mosquito trap?
A. Mosquito traps capture mosquitoes by mimicking the different attractants that lure mosquitoes. These include exhaled carbon dioxide, human scents, and body heat. Lured by these chemicals, the mosquito is drawn towards that trap and captured by the impeller fan. The mosquito then adheres to a sticky surface on the device and is electrocuted.
Q. Which is more effective—mosquito nets or traps?
A. While both offer sufficient protection against mosquitoes, the World Health Organization and the U.S. Center for Disease Control both highly recommend using various netting options to reduce contact with mosquitoes.
Netting offers effective protection from mosquitoes and other insects, and also helps decrease the risk of contracting any mosquito-borne diseases. To work properly, netting should have a mesh size of 1.2mm X 1.2mm, have 120-200 holes per square inch, and should be made of either polyester or polyamide. To ensure the best protection, all mosquito netting should be pretreated with insecticides.
Q. What is the mosquito magnet?
A. The Mosquito Magnet captures mosquitoes by giving off carbon dioxide, heat, and moisture. This is combined with an attractant called octenol, which is a natural plant pheromone. Once the Mosquito Magnet attracts the bugs it vacuums the insects into a net where they dehydrate and die. The Mosquito Magnet not only captures mosquitoes, but also biting midges, black flies, and sandflies.
Q. Will mosquito repellent offer me 100% protection?
A. Mosquito repellents made with DEET (N-diethyl meta-toluamide) have been proven to be the most effective, offering almost 100% protection against biting insects. The more DEET that a repellent contains, the longer it can protect you from mosquito bites. A higher percentage of DEET in a repellent indicates that it will last on your skin for a longer amount of time. For the best protection, use a repellent that has 20% to 35% DEET in it. Avoid applying a product that contains more than 35% DEET on a child, as it may have side effects.
Q. What should I do if my child has been bit?
A. If your child has an allergy to mosquito bites (fever, nausea), you must contact a physician immediately. If your child only experiences the usual swelling and itching associated with mosquito bites, then follow these simple steps to making your child’s bite as comfortable as possible:
- Wash the infected area with soap and water
- Use a cool compress
- Apply anti-itching medications or creams (like Calamine lotion)
Q. How can I control mosquitoes around my home?
A. Mosquitoes around the home can be reduced significantly by minimizing the amount of standing water available for mosquito breeding. You can reduce the standing water around your home in a variety of ways:
- Throw out tin cans, pots, or any other containers that can accumulate water
- Make sure to empty any water from used or discarded tires on your property
- Clean roof gutters annually
- Change the water in bird baths and wading pools in a weekly basis
- Clean and chlorinate swimming pools
Q. Is it true that only female mosquitoes bite? If so, why don’t
male mosquitoes?
A. Female mosquitoes are indeed the biters. They need the blood for their eggs. Human blood contains protein, and the female mosquito needs the protein to develop her eggs.
Q. How long can a mosquito live?
A. Mosquitoes typically live about two weeks, although some adult mosquitoes can survive the winter in a sort of hibernating state which enables them to survive for up to 8 months.
Remember, many of the larvae in ponds are eaten by fish and a large percentage of adult mosquitoes end up as dinner for birds, spiders and dragonflies. Thank goodness these predators are around, or else our mosquito problems would be far worse!
Q. Why does my friend seem to get more mosquito bites than I do?
A. There are several theories about why some people are more apt to be victims of mosquitoes than others, but some of the more popular and plausible ideas revolve around human blood types and odors. It is felt that mosquitoes are attracted by the carbon dioxide we exhale, and then after they zoom in on us, they sense the moisture and heat of our bodies, and decide if we fit their preferences for a blood meal.
Q. Aren’t mosquitoes mainly found near ponds and marshes?
A. Although those are prime breeding areas for many mosquitoes, some mosquitoes will breed in stagnant water just about anywhere, including old tires, swimming pools, buckets, trash cans and overturned trash can lids, birdbaths, clogged rainspouts and gutters, ditches, trenches, tire ruts, old flowerpots and even knot-holes in trees.
As you can see, if there is enough space for a small puddle, there is enough space for mosquitoes to breed!
Q. What can I do to keep mosquitoes from breeding around near my
home?
A. Make sure you do not have any standing water in your yard. Be sure to change the water in birdbaths every week. Dump water from any buckets, trash cans, wading pools, old tires, etc. and situate them so water cannot accumulate in them. Keep your gutters and rainspouts clear so rainwater can run freely down them.
If you live near a pond or marshland and already have quite a few mosquitoes, you may want to use mosquito traps to catch and kill mosquitoes.
It is important to make sure you are not harming beneficial insects in your quest to eliminate your mosquito problem.
Q. How many types of mosquitoes are there in the entire world?
A. If by types, you are referring to species, there are estimates that range from 2500 to 2700 species of mosquitoes in the world. Some estimates have been as high as 3000.
Q. Can mosquitoes survive in very cold climates?
A. Yep, just ask anyone living in Alaska! There are places in Alaska where mosquitoes thrive. Mosquitoes that do survive cold winters are either hibernating adults or overwintering eggs.
Q. Where do mosquitoes go in the winter?
A. Mosquitoes, like most insects, are cold blooded creatures. As a result, they are incapable of regulating body heat and their temperature is essentially the same as their surroundings. Mosquitoes function best at 80o F, become lethargic at 60o F and cannot function below 50o F. In tropical areas, mosquitoes are active year round. In temperate climates, adult mosquitoes become inactive with the onset of cool weather and enter hibernation to live through the winter. Some kinds of mosquitoes have winter hardy eggs and hibernate as embryos in eggs laid by the last generation of females in late summer. The eggs are usually submerged under ice and hatch in spring when water temperatures rise. Other kinds of mosquitoes overwinter as adult females that mate in the fall, enter hibernation in animal burrows, hollow logs or basements and pass the winter in a state of torpor. In spring, the females emerge from hibernation, blood feed and lay the eggs that produce the next generation of adults. A limited number of mosquitoes overwinter in the larval stage, often buried in the mud of freshwater swamps. When temperatures rise in spring, these mosquitoes begin feeding, complete their immature growth and eventually emerge as adults to continue their kind.
Q. How many kinds of mosquitoes are there?
A. About 3000 species of mosquitoes have been described on a world-wide basis. Approximately 150 are known to occur in North America. The term "Mosquito State" is appropriate for New Jersey because 63 species of mosquitoes have been found within its boundaries, to date. Scientists group species by genus on the basis of the physical characteristics they share. The 3000 mosquito species found in the world are divided among 28 different genera. The genus Aedes contains some of the worst pests. Many members of the genus Anopheles have the ability to transmit human malaria. Ten different genera occur in New Jersey including: Aedes, Anopheles, Culex, Culiseta, Coquillettidia, Psorophora, Orthopodomyia, Uranotaenia, Toxorhynchites and Wyeomyia. It is sometimes more convenient to group mosquitoes by the breeding habitat they use. The major habitat groups found in New Jersey include: "Snowpool Mosquitoes", "Floodwater Mosquitoes", "Swamp Breeding Mosquitoes" and "Container Breeding Mosquitoes".
Q. Why do mosquitoes bite?
A. Mosquitoes belong to a group of insects that requires blood to develop fertile eggs. Males do not lay eggs, thus, male mosquitoes do not bite. The females are the egg producers and "host-seek" for a blood meal. Female mosquitoes lay multiple batches of eggs and require a blood meal for every batch they lay. Few people realize that mosquitoes rely on sugar as their main source of energy. Both male and female mosquitoes feed on plant nectar, fruit juices and liquids that ooze from plants. The sugar is burned as fuel for flight and is replenished on a daily basis. Blood is reserved for egg production and is imbibed less frequently.
Q. Why do mosquitoes leave welts when they bite?
A. When a female mosquito pierces the skin with her mouthparts, she injects a small amount of saliva into the wound before drawing blood. The saliva makes penetration easier and prevents the blood from clotting in the narrow channel of her food canal. The welts that appear after the mosquito leaves is not a reaction to the wound but an allergic reaction to the saliva injected to prevent clotting. In most cases, the itching sensation and swellings subside within several hours. Some people are highly sensitive and symptoms persist for several days. Scratching the bites can result in infection if bacteria from the fingernails are introduced to the wounds.
Q. Why are some people more attractive to mosquitoes than others?
A. Scientists are still investigating the complexities involved with mosquito host acceptance and rejection. Some people are highly attractive to mosquitoes and others are rarely bothered. Mosquitoes have specific requirements to satisfy and process many different factors before they feed. Many of the mosquito's physiological demands are poorly understood and many of the processes they use to evaluate potential blood meal hosts remain a mystery. Female mosquitoes use the CO2 we exhale as their primary cue to our location. A host seeking mosquito is guided to our skin by following the slip stream of CO2 that exudes from our breath. Once they have landed, they rely on a number of short range attractants to determine if we are an acceptable blood meal host. Folic acid is one chemical that appears to be particularly important. Fragrances from hair sprays, perfumes, deodorants and soap can cover these chemical cues. They can also function to either enhance or repel the host seeking drive. Dark colors capture heat and make most people more attractive to mosquitoes. Light colors refract heat and are generally less attractive. Detergents, fabric softeners, perfumes and body odor can counteract the effects of color. In most cases, only the mosquito knows why one person is more attractive than another.
Q. How long do mosquitoes live?
A. Mosquitoes are relatively fragile insects with an adult life span that lasts about 2 weeks. The vast majority meet a violent end by serving as food for birds, dragonflies and spiders or are killed by the effects of wind, rain or drought. The mosquito species that only have a single generation each year are longer lived and may persist in small numbers for as long as 2-3 months if environmental conditions are favorable. Mosquitoes that hibernate in the adult stage live for 6-8 months but spend most of that time in a state of torpor. Some of the mosquito species found in arctic regions enter hibernation twice and take more than a year to complete their life cycle.
Q. Can mosquitoes carry diseases?
A. Any insect that feeds on blood has the potential of transmitting disease organisms from human to human. Mosquitoes are highly developed blood-sucking insects and are the most formidable transmitters of disease in the animal kingdom. Mosquito-borne diseases are caused by human parasites that have a stage in their life cycle that enters the blood stream. The female mosquito picks up the blood stage of the parasite when she imbibes blood to develop her eggs. The parasites generally use the mosquito to complete a portion of their own life cycle and either multiply, change in form inside the mosquito or do both. After the mosquito lays her eggs, she seeks a second blood meal and transmits the fully developed parasites to the next unwitting host. Malaria is a parasitic protozoan that infects the blood cells of humans and is transmitted from one human to the next by Anopheles mosquitoes. Encephalitis is a virus of the central nervous system that is passed from infected birds to humans by mosquitoes that accept birds as blood meal hosts in addition to humans. Yellow fever is a virus infection of monkeys that can either be transmitted from monkey to human or from human to human in tropical areas of the world. Dog heartworm is a large filarial worm that lives in the heart of dogs but produces a blood stage small enough to develop in a mosquito. The dog heartworm parasite does not develop properly in humans and is not regarded as a human health problem. A closely related parasite, however, produces human elephantiasis in some tropical areas of the world, a debilitating mosquito-borne affliction that results in grossly swollen arms legs and genitals.
Q. Can mosquitoes transmit AIDS?
A. The HIV virus that produces AIDS in humans does not develop in mosquitoes. If HIV infected blood is taken up by a mosquito the virus is treated like food and digested along with the blood meal. If the mosquito takes a partial blood meal from an HIV positive person and resumes feeding on a non-infected individual, insufficient particles are transferred to initiate a new infection. If a fully engorged mosquito with HIV positive blood is squashed on the skin, there would be insufficient transfer of virus to produce infection. The virus diseases that use insects as agents of transfer produce tremendously high levels of parasites in the blood. The levels of HIV that circulate in human blood are so low that HIV antibody is used as the primary diagnosis for infection.
Dengue
Q. What is Dengue fever (DF)?
A. Dengue infection is caused by a virus, often manifests as dengue fever. Occasionally the patient suffering from dengue may develop bleeding from sites like nose, gums or skin. Sometimes, the patient may have coffee ground vomiting or black stools which indicates bleeding in gastro intestinal tracts. Rarely the patient suffering from dengue may develop shock, then it is called dengue shock syndrome (DSS).
Q. Is dengue an emerging infectious disease?
A. Yes. All types of Dengue viruses are re-emerging worldwide and causing larger and more frequent epidemics, especially in cities in the tropics. Several factors are contributing to the resurgence of dengue fever:
- No effective mosquito control efforts are underway in most countries with dengue.
- Public health systems to detect and control epidemics are deteriorating around the world.
- Rapid growth of cities in tropical countries has led to overcrowding, urban decay, and substandard sanitation, allowing more mosquitoes to live closer to more people.
- The increase in non-biodegradable plastic packaging and discarded tyres is creating new breeding sites for mosquitoes.
- Increased air travel is helping people infected with dengue viruses to move easily from city to city.
Q. Where is dengue prevalent?
A. Dengue viruses occur in most tropical areas of the world. Dengue is common in Africa, Asia, the Pacific, Australia, and the Americas. It is widespread in the Caribbean basin. Dengue is most common in cities but can also be found in rural areas. It is rarely found in mountainous
areas above 4,000 feet.
Q. When can Dengue be suspected?
A. Dengue should be suspected when you have sudden onset of fever. The fever is high 103-105 degrees F or 39-40 degrees C. It is accompanied with severe headache (mostly in the forehead), pain behind the eyes, body aches and pains, rash on the skin and nausea or vomiting. The fever lasts for 5-7 days. In some patients, fever comes down on 3rd or 4th day but comes back. All the above symptoms and signs may not be present in the patient. The patient feels much discomfort after the illness. The severity of the joint pain has given
dengue the name - breakbone fever..
Q. What is the difference between suspected and probable case of dengue?
A. Dengue patients are characterized by reduced platelets or an increase in blood haematocrit. Patients with dengue may not have a high haematocrit if the person was anaemic to start with.
Q. Can you get dengue again after suffering from it once?
A. It is possible to get dengue more than once. Dengue can occur because of 4 different but related strains of dengue virus. If a person has suffered from one virus, there can be a repeat occurrence of dengue if a different strain is involved subsequently. Being affected by one
strain offers no protection against the others. A person can suffer from dengue more than once in her/his lifetime.
Q. How can someone get dengue fever?
A. Dengue fever occurs following the bite of an infected mosquito Aedes aegypti ((Tiger mosquito) )and Ae.albopictus which is characterized by a peculiar white spotted body and legs and is easy to recognize even by layman. It breeds in clean water and has a flight range of only 100 . 200 metres. The mosquito gets the Dengue virus after biting a human being infected with dengue virus.
Q. Can I get dengue fever from another person?
A. Dengue does not spread directly from person to person. It is only spread through the bite of an infected mosquito.
Q. When does dengue develop after getting the infection?
A. After the entry of the virus in the person, it multiplies in the lymph glands in the body. The symptoms develop when the virus has multiplied in sufficient numbers to cause the symptoms. This happens generally about 4-6 days after getting infected with the virus.
Q. Can people suffer from dengue and not appear ill?
A. Yes. There are many people who are infected with the virus and do not suffer from any signs or symptoms of the disease. For every patient with symptoms and signs there may be 4-5 persons with no symptoms or with very mild symptoms.
Q. Is it possible to treat dengue at home?
A. Most patients with dengue fever can be treated at home. They should take rest, drink plenty of fluids that are available at home and eat nutritious diet. Whenever available, Oral Rehydration Salt/ORS (commonly used in treating diarrhoea) is preferable. Sufficient fluid intake is very important and becomes more important in case DF progresses into DHF or DSS where loss of body fluid / blood is the most salient feature.It is important to look for danger signs and contact the doctor as soon as any one or more of these are found.
Q. What is the possible treatment for Dengue?
A. Like most viral diseases, there is no specific cure for dengue fever. Antibiotics do not help. Paracetamol (can be purchased without prescription) is the drug of choice to bring down fever and joint pain. Other medicines such as Aspirin and Brufen should be avoided since they can increase the risk of bleeding. Doctors should be very careful when prescribing medicines. Any medicine that decreases platelets should be avoided.
Malaria
Q. What is malaria?
A. Malaria is a serious and sometimes fatal disease caused by a parasite that commonly infects a certain type of mosquito which feeds on humans. People who get malaria are typically very sick with high fevers, shaking chills, and flu-like illness. Four kinds of malaria parasites have long been known to infect humans: Plasmodium falciparum, P. vivax, P. ovale, and P. malariae. Recently, it has been recognized that P. knowlesi, a type of malaria that naturally infects macaques in Southeast Asia, also infects humans, causing malaria that is transmitted from animal to human ("zoonotic" malaria). P. falciparum is the type of malaria that is most likely to result in severe infections and if not promptly treated, may lead to death. Although malaria can be a deadly disease, illness and death from malaria can usually be prevented.
About 1,500 cases of malaria are diagnosed in the United States each year. The vast majority of cases in the United States are in travelers and immigrants returning from parts of the world where malaria transmission occurs, including sub-Saharan Africa and South Asia.
The World Health Organization estimates that in 2008, 190 - 311 million clinical cases of malaria occurred, and 708,000 - 1,003,000 people died of malaria, most of them children in Africa. Because malaria causes so much illness and death, the disease is a great drain on many national economies. Since many countries with malaria are already among the poorer nations, the disease maintains a vicious cycle of disease and poverty.
How People Get Malaria (Transmission)
Q. How is malaria transmitted?
A. Usually, people get malaria by being bitten by an infective female Anopheles mosquito. Only Anopheles mosquitoes can transmit malaria and they must have been infected through a previous blood meal taken from an infected person. When a mosquito bites an infected person, a small amount of blood is taken in which contains microscopic malaria parasites. About 1 week later, when the mosquito takes its next blood meal, these parasites mix with the mosquito's saliva and are injected into the person being bitten.
Because the malaria parasite is found in red blood cells of an infected person, malaria can also be transmitted through blood transfusion, organ transplant, or the shared use of needles or syringes contaminated with blood. Malaria may also be transmitted from a mother to her unborn infant before or during delivery ("congenital" malaria).
Q. Is malaria a contagious disease?
A. No. Malaria is not spread from person to person like a cold or the flu, and it cannot be sexually transmitted. You cannot get malaria from casual contact with malaria-infected people, such as sitting next to someone who has malaria.
Who Is at Risk
Q. Who is at risk for malaria?
A. Anyone can get malaria. Most cases occur in people who live in countries with malaria transmission. People from countries with no malaria can become infected when they travel to countries with malaria or through a blood transfusion (although this is very rare). Also, an infected mother can transmit malaria to her infant before or during delivery.
Q. Who is most at risk of getting very sick and dying from malaria?
Plasmodium falciparum is the type of malaria that most often causes severe and life-threatening malaria; this parasite is very common in many countries in Africa south of the Sahara desert. People who are heavily exposed to the bites of mosquitoes infected with P. falciparum are most at risk of dying from malaria. People who have little or no immunity to malaria, such as young children and pregnant women or travelers coming from areas with no malaria, are more likely to become very sick and die. Poor people living in rural areas who lack knowledge, money, or access to health care are at greater risk for this disease. As a result of all these factors, an estimated 90% of deaths due to malaria occur in Africa south of the Sahara; most of these deaths occur in children under 5 years of age.
Symptoms and Diagnosis
Q. What are the signs and symptoms of malaria?
A. Symptoms of malaria include fever and flu-like illness, including shaking chills, headache, muscle aches, and tiredness. Nausea, vomiting, and diarrhea may also occur. Malaria may cause anemia and jaundice (yellow coloring of the skin and eyes) because of the loss of red blood cells. If not promptly treated, the infection can become severe and may cause kidney failure, seizures, mental confusion, coma, and death.
Q. How soon will a person feel sick after being bitten by an infected mosquito?
A. For most people, symptoms begin 10 days to 4 weeks after infection, although a person may feel ill as early as 7 days or as late as 1 year later. Two kinds of malaria, P. vivax and P. ovale, can occur again (relapsing malaria). In P. vivax and P. ovale infections, some parasites can remain dormant in the liver for several months up to about 4 years after a person is bitten by an infected mosquito. When these parasites come out of hibernation and begin invading red blood cells ("relapse"), the person will become sick.
Q. How do I know if I have malaria for sure?
A. Most people, at the beginning of the disease, have fever, sweats, chills, headaches, malaise, muscles aches, nausea, and vomiting. Malaria can very rapidly become a severe and life-threatening disease. The surest way for you and your health-care provider to know whether you have malaria is to have a diagnostic test where a drop of your blood is examined under the microscope for the presence of malaria parasites. If you are sick and there is any suspicion of malaria (for example, if you have recently traveled in a country where malaria transmission occurs), the test should be performed without delay.
Q. What is known about the long-term effects of drugs that are commonly used to prevent and treat malaria?
A. In general, the drugs used to prevent and treat malaria have been shown to be well-tolerated for at least 1 year or more.
Q. Is it safe to buy my malaria drugs in the country where I will be traveling?
A. Buying medications abroad has its risks. The drugs could be of poor quality because of the way they are produced. The drugs could contain contaminants or they could be counterfeit drugs and therefore may not provide you the protection you need against malaria. In addition, some medications that are sold overseas are not used anymore in the United States or were never sold here. These drugs may not be safe or their safety has never been evaluated.
It would be best to purchase all the medications that you need before you leave the United States. As a precaution, note the name of the medication(s) and the name of the manufacturer(s). That way, in case of accidental loss, you can replace the drug(s) abroad at a reliable vendor.
Q. Isn't there a malaria vaccine? And if not, why?
A. There is currently no malaria vaccine approved for human use. The malaria parasite is a complex organism with a complicated life cycle. Its antigens are constantly changing and developing a vaccine against these varying antigens is very difficult. In addition, scientists do not yet totally understand the complex immune responses that protect humans against malaria. However, many scientists all over the world are working on developing an effective vaccine. Clinical trials with possible vaccines are currently happening. Because other methods of fighting malaria, including drugs, insecticides, and insecticide-treated bed nets, have not succeeded in eliminating the disease, the search for a vaccine is considered to be one of the most important research projects in public health.
Malaria and Infants and Children
Q. Should infants and children be given antimalarial drugs?
A. Yes, but not all types of malaria drugs. Children of any age can get malaria and any child traveling to an area where malaria transmission occurs should use the recommended prevention measures, which often include an antimalarial drug. However, some antimalarial drugs are not suitable for children. Doses are based on the child's weight.
Other Preventive Measures
Q. I live in an area where malaria is a problem. How can I prevent myself and my family from getting sick?
A. You and your family can prevent malaria by:
- Keeping mosquitoes from biting you, especially at night
- Taking antimalarial drugs to kill the parasites
- Spraying insecticides on your home's walls to kill adult mosquitoes that come inside
- Sleeping under bed nets—especially effective if they have been treated with insecticide, and
- Using insect repellent and wearing long-sleeved clothing if out of doors at night.
After Returning from an Area That Has Malaria
Q. How long after returning from an area with malaria could I develop malaria?
A. Any traveler who becomes ill with a fever or flu-like illness while traveling, and up to 1 year after returning home, should immediately seek professional medical care. You should tell your health-care provider that you have been traveling in an area where malaria transmission occurs and ask to be tested for malaria infection.
Q. Can I give blood if I have been in a country where there is malaria?
A. It depends on what areas of that country you visited, how long ago you were there, and whether you ever had malaria. In general, most travelers to an area with malaria are deferred from donating blood for 1 year after their return. People who used to live in countries where malaria transmission occurs cannot donate blood for 3 years. People diagnosed with malaria cannot donate blood for 3 years after treatment, during which time they must have remained free of symptoms of malaria.
Blood banks follow strict guidelines for accepting or deferring donors who have been in malaria-endemic areas. They do this to avoid collecting blood for transfusions from an infected donor. In the United States during the period 1963-1999, there were 93 cases reported to CDC where people acquired malaria through a transfusion. Because of these control measures, transfusion-transmitted malaria is very rare in the United States and occurs at a rate of less than 1 per million units of blood transfused.
Treating Malaria
Q. When should malaria be treated?
A. The disease should be treated early in its course, before it becomes serious and life-threatening. Several good antimalarial drugs are available, and should be taken early on. The most important step is to think about malaria if you are presently in, or have recently been in, an area with malaria, so that the disease is diagnosed and treated right away.
Q. What is the treatment for malaria?
A. Malaria can be cured with prescription drugs. The type of drugs and length of treatment depend on the type of malaria, where the person was infected, their age, whether they are pregnant, and how sick they are at the start of treatment.
Q. When is malaria self-treatment recommended?
A. Very rarely. Travelers who are taking effective malaria preventive drugs but who will be traveling for an extended period of time or who will be at higher risk of developing a malaria infection may decide, in consultation with their health-care provider, to take along malaria treatment medication in case they develop malaria while traveling. If the traveler develops symptoms of malaria, they should immediately seek medical attention so that they can be examined and diagnosed appropriately. If they are diagnosed with malaria, they will then already have with them a reliable supply of an effective malaria treatment medicine to take. Malaria self-treatment should begin right away if fever, chills, or other influenza-like illness symptoms occur and if professional medical care is not available within 24 hours. Self-treatment of a possible malarial infection is only a temporary measure and immediate medical care is important. Appropriate options for a reliable supply of malaria treatment medicines are atovaquone/proguanil or artemether/lumefantrine.
Q. If I get malaria, will I have it for the rest of my life?
A. No, not necessarily. Malaria can be treated. If the right drugs are used, people who have malaria can be cured and all the malaria parasites can be cleared from their body. However, the disease can continue if it is not treated or if it is treated with the wrong drug. Some drugs are not effective because the parasite is resistant to them. Some people with malaria may be treated with the right drug, but at the wrong dose or for too short a period of time.
Two types (species) of parasites, Plasmodium vivax and P. ovale, have liver stages and can remain in the body for years without causing sickness. If not treated, these liver stages may reactivate and cause malaria attacks ("relapses") after months or years without symptoms. People diagnosed with P. vivax or P. ovale are often given a second drug to help prevent these relapses. Another type of malaria, P. malariae, if not treated, has been known to stay in the blood of some people for several decades.
However, in general, if you are correctly treated for malaria, the parasites are eliminated and you are no longer infected with malaria.
Where Malaria Occurs
Q. Where does malaria occur?
A. Malaria typically is found in warmer regions of the world -- in tropical and subtropical countries. Higher temperatures allow the Anopheles mosquito to thrive. Malaria parasites, which grow and develop inside the mosquito, need warmth to complete their growth before they are mature enough to be transmitted to humans.
Malaria occurs in more than 100 countries and territories. About half of the world's population is at risk. Large areas of Africa and South Asia and parts of Central and South America, the Caribbean, Southeast Asia, the Middle East, and Oceania are considered areas where malaria transmission occurs.
Yet malaria does not occur in all warm climates. For example, malaria has been eliminated in some countries with warm climates, while a few other countries have no malaria because Anopheles mosquitoes are not found there.
Q. Why is malaria so common in Africa?
A. In Africa south of the Sahara, the principal malaria mosquito, Anopheles gambiae, transmits malaria very efficiently. The type of malaria parasite most often found, Plasmodium falciparum, causes severe, potentially fatal disease. Lack of resources and political instability can prevent the building of solid malaria control programs. In addition, malaria parasites are increasingly resistant to antimalarial drugs, presenting one more barrier to malaria control on that continent.
Q. In some countries, malaria is said to exist in "rural" areas. How would one know if an area is rural vs urban?
A. What constitutes a rural area can vary by country. In general, urbanization can be said to involve both population size and economic development of an area in which there is concentrated commercial activity, such as manufacturing, the sale of goods and services, and transportation. Rural areas tend to have less commercial activity, less population density, more green space, and agriculture may be a main feature.
Eradication and Elimination
Q. Wasn't malaria eradicated years ago?
A. No. Eradication means that no more malaria exists in the world. Malaria has been eliminated from many developed countries with temperate climates. However, the disease remains a major health problem in many developing countries, in tropical and subtropical parts of the world.
An eradication campaign was started in the 1950s, but it failed globally because of problems including the resistance of mosquitoes to insecticides used to kill them, the resistance of malaria parasites to drugs used to treat them, and administrative issues. In addition, the eradication campaign never involved most of Africa, where malaria is the most common.
Japanese Encephalitis
Q. How is Japanese encephalitis transmitted?
A. By rice field breeding mosquitoes (primarily the Culex tritaeniorhynchus group) that become infected with Japanese encephalitis virus (a flavivirus antigenically related to St. Louis encephalitis virus).
Q. How do people get Japanese encephalitis?
A. By the bite of mosquitoes infected with the Japanese encephalitis virus.
Q. What is the basic transmission cycle?
A. Mosquitoes become infected by feeding on domestic pigs and wild birds infected with the Japanese encephalitis virus. Infected mosquitoes then transmit the Japanese encephalitis virus to humans and animals during the feeding process. The Japanese encephalitis virus is amplified in the blood systems of domestic pigs and wild birds.
Q. Could you get the Japanese encephalitis from another person?
A. No, Japanese encephalitis virus is NOT transmitted from person-to-person. For example, you cannot get the virus from touching or kissing a person who has the disease, or from a health care worker who has treated someone with the disease.
Q. Could you get Japanese encephalitis from animals other than domestic pigs, or from insects other than mosquitoes?
A. No. Only domestic pigs and wild birds are carriers of the Japanese encephalitis virus.
Q. What are the symptoms of Japanese encephalitis?
A. Mild infections occur without apparent symptoms other than fever with headache. More severe infection is marked by quick onset, headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, occasional convulsions (especially in infants) and spastic (but rarely flaccid) paralysis.
Q. What is the incubation period for Japanese encephalitis?
A. Usually 5 to 15 days.
Q. What is the mortality rate of Japanese encephalitis?
A. Case-fatality rates range from 0.3% to 60%.
Q. How many cases of Japanese encephalitis occur in the world and the U.S.?
A. Japanese encephalitis is the leading cause of viral encephalitis in Asia with 30-50,000 cases reported annually. Fewer than 1 case/year is reported in U.S. civilians and military personnel traveling to and living in Asia. Rare outbreaks in U.S. territories in Western Pacific have occurred.
Q. How is Japanese encephalitis treated?
A. There is no specific therapy. Intensive supportive therapy is indicated.
Q. Is the disease seasonal in its occurrence?
A. Seasonality of the illness varies by country (see table).
Q. Who is at risk for getting Japanese encephalitis?
A. Residents of rural areas in endemic locations, active duty military deployed to endemic areas, and expatriates who visit rural areas. Japanese encephalitis does not usually occur in urban areas (see table).
Q. Where do Japanese Encephalitis outbreaks occur?
A. Japanese encephalitis outbreaks are usually circumscribed and do not cover large areas. They usually do not last more than a couple of months, dying out after the majority of the pig amplifying hosts have become infected. Birds are the natural hosts for Japanese encephalitis. Epidemics occur when the virus is brought into the peridomestic environment by mosquito bridge vectors where there are pigs, which serve as amplification hosts, infecting more mosquitoes which then may infect humans. Countries which have had major epidemics in the past, but which have controlled the disease primarily by vaccination, include China, Korea, Japan, Taiwan and Thailand. Other countries that still have periodic epidemics include Viet Nam, Cambodia, Myanmar, India, Nepal, and Malaysia.
Q. Who should be vaccinated against Japanese encephalitis?
A. The statement of the Advisory Committee on Immunization Practices (ACIP) provides recommendations for use of JE vaccine among travelers and laboratory workers. (See: Centers for Disease Control and Prevention. Japanese Encephalitis Vaccines, Recommendations of the Advisory Committee on Immunization Practices (ACIP), Morbidity and Mortality Weekly Report, Mar 12, 2010: 59(01);1-27) The 2-page Vaccine Information Statement provides helpful information on who should be vaccinated against Japanese encephalitis virus and the benefits and risks of the vaccine.
Q. Where can I get more information on Japanese encephalitis?
A. See the CDC Japanese Encephalitis Home Page (http://www.cdc.gov/ncidod/dvbid/jencephalitis) and CDC Health Information for Travelers to Southeast Asia (http://www.cdc.gov/travel/seasia.htm).
Lymphatic Filariasis
Q. What is lymphatic filariasis?
A. Lymphatic filariasis is a parasitic disease caused by microscopic, thread-like worms. The adult worms only live in the human lymph system. The lymph system maintains the body's fluid balance and fights infections.
Lymphatic filariasis affects over 120 million people in 80 countries throughout the tropics and sub-tropics of Asia, Africa, the Western Pacific, and parts of the Caribbean and South America. You cannot get infected with the worms in the United States.
Q. How is lymphatic filariasis spread?
A. The disease spreads from person to person by mosquito bites. When a mosquito bites a person who has lymphatic filariasis, microscopic worms circulating in the person's blood enter and infect the mosquito. People get lymphatic filariasis from the bite of an infected mosquito. The microscopic worms pass from the mosquito through the skin, and travel to the lymph vessels. In the lymph vessels they grow into adults. An adult worm lives for about 5-7 years. The adult worms mate and release millions of microscopic worms, called microfilariae, into the blood. People with the worms in their blood can give the infection to others through mosquitoes.
Q. Who is at risk for infection?
A. Repeated mosquito bites over several months to years are needed to get lymphatic filariasis. People living for a long time in tropical or sub-tropical areas where the disease is common are at the greatest risk for infection. Short-term tourists have a very low risk. An infection will show up on a blood test.
Q. What are the signs and symptoms of lymphatic filariasis?
A. Most infected people are asymptomatic and will never develop clinical symptoms, despite the fact that the parasite damages the lymph system. A small percentage of persons will develop lymphedema. This is caused by improper functioning of the lymph system that results in fluid collection and swelling. This mostly affects the legs, but can also occur in the arms, breasts, and genitalia. Most people develop these clinical manifestations years after being infected.
The swelling and the decreased function of the lymph system make it difficult for the body to fight germs and infections. Affected persons will have more bacterial infections in the skin and lymph system. This causes hardening and thickening of the skin, which is called elephantiasis. Many of these bacterial infections can be prevented with appropriate skin hygiene.
Men can develop hydrocele or swelling of the scrotum due to infection with one of the parasites that causes LF specifically W. bancrofti.
Filarial infection can also cause pulmonary tropical eosinophilia syndrome. This syndrome is typically found in infected persons in Asia. Clinical manifestations of pulmonary tropical eosinophilia syndrome include cough, shortness of breath, and wheezing. The eosinophilia is often accompanied by high levels of IgE (Immunoglobulin E) and antifilarial antibodies.
Q. How is lymphatic filariasis diagnosed?
A. The standard method for diagnosing active infection is the identification of microfilariae by microscopic examination. This is not always feasible because in most parts of the world, microfilariae are nocturnally periodic, which means that they only circulate in the blood at night. For this reason, the blood collection has to be done at night to coincide with the appearance of the microfilariae.
Serologic techniques provide an alternative to microscopic detection of microfilariae for the diagnosis of lymphatic filariasis. Because lymphedema may develop many years after infection, lab tests are often negative with these patients.
Q. How can I prevent infection?
A. Avoiding mosquito bites is the best form of prevention. The mosquitoes that carry the microscopic worms usually bite between the hours of dusk and dawn. If you live in or travel to an area with lymphatic filariasis:
- Sleep under a mosquito net.
- Wear long sleeves and trousers.
- Use mosquito repellent on exposed skin between dusk and dawn.
Q. What is the treatment for lymphatic filariasis?
A. People infected with adult worms can take a yearly dose of medicine, called diethylcarbamazine (DEC), that kills the microscopic worms circulating in the blood. While this drug does not kill all of the adult worms, it does prevent infected people from giving the disease to someone else.
Lymphedema and elephantiasis are not indications for DEC treatment because most people with lymphedema are not actively infected with the filarial parasite. Physicians can obtain DEC from CDC after lab results confirm infection.
Even after the adult worms die, lymphedema can develop. You can ask your physician for a referral to see a lymphedema therapist for specialized care. Prevent the lymphedema from getting worse by following several basic principles:
- Carefully wash the swollen area with soap and water every day.
- Elevate and exercise the swollen arm or leg to move the fluid and improve the lymph flow.
- Disinfect any wounds. Use antibacterial or antifungal cream if necessary.
Chikungunya
Q. What is Chikungunya?
A. Chikungunya is a form of viral fever caused by an Alphavirus that is spread by mosquito bites from Aedes mosquito. Chikungunya is derived from the African word meaning ‘that which bends up’ in reference to the stooped posture developed as a result of the arthritic symptoms of the disease.
Q. What are the signs and symptoms of Chikungunya?
A. One to three days of fever with joint pain usually with swelling, headache, vomiting,
photophobia, with or without rashes.
Q. How to differentiate from other fevers?
A. Chikungunya fever is usually self-limiting. The fever usually lasts for about three days.
The joint swelling and pain often persist even after the recovery from the fever up to one
to three weeks or even months depending on the age of the patient.
Q. How is it diagnosed?
A. The diagnostic tests include detection of antigens or antibodies in the blood, using ELISA or molecular techniques like polymerase chain reaction (PCR).However, there is no need for a blood test to confirm each Chikungunya case in areas reporting Chikungunya epidemic outbreak. Clinical diagnosis is enough. Fever with joint pain followed by swelling are the cardinal signs of Chikungunya.
Q. What is the treatment of Chikungunya infection?
A. There is no specific treatment of Chikungunya infection and it is usually self-limiting. But analgesics, antipyretics like paracetamol, diclofenac sodium, chloroquine along with fluid supplementation are recommended to manage the infection and relieve fever, joint pains and swelling. Drugs like aspirin and steroids should be avoided.
Q. Is there a vaccine for Chikungunya?
A. There is no vaccine currently available.
Q. How is Chikungunya transmitted? Is it transmissible from human to human?
A. Chikungunya is transmitted by the bite of the infected Aedes mosquito from an infected
person to a healthy person. The disease does not get transmitted directly from human to
human (i.e. it is not a contagious disease). In a pregnant woman with Chikungunya there
is risk of transmitting the disease to her foetus.
Q. Who is at risk for Chikungunya?
A. Anyone who is bitten by an infected mosquito can get Chikungunya.
Q. How soon after exposure do symptoms appear?
A. The time between the bite of a mosquito carrying Chikungunya virus and the start of
symptoms ranges from one to twelve days.
Q. Will Chikungunya cause death?
A. No. Worldwide statistics clearly show that Chikungunya directly does not cause death.
There may be deaths due to various other causes during Chikungunya outbreak.
Q. Whether the person once recovered from the disease will get it again?
A. No. One attack of Chikungunya will give life-long immunity.
Q. How can one prevent Chikungunya infection?
A. Since there is no vaccine or specific treatment, controlling Chikungunya transmission,
i.e., elimination of Aedes mosquito breeding sites or source reduction in domestic and
peri-domestic areas and taking personal protection measures to prevent mosquito bites
prevents infection.
Q. When and where does the Aedes Aegypti mosquito bite?
A. The Aedes aegypti mosquito is usually a day biter, bites repeatedly and feeds on human
beings in domestic and peri-domestic situations.
Q. Where do the Aedes mosquitoes breed?
A. The Aedes mosquitoes breed in clean water stored within the house like tanks (overhead/
underground, etc), other containers, flower vases, planters, dip trays, grinding stone, etc.
These mosquitoes also breed in our surroundings in discarded and unused containers
and materials like coconut shells, plastic cups, old tyres, etc.
Q. How to eliminate the breeding of mosquitoes?
A. Prevent water collections in and around the domestic and peri-domestic areas.
Q. How to get protection from mosquito bites?
A. Insecticide spray should be carried out to kill mosquitoes. In addition, insecticide treated
mosquito curtains/bed nets (ITNs) should be used. Community/patients should wear
protective clothing, i.e., long sleeved shirts, full pants, etc. Insect repellents may also be
used.
Q. What are the high risk groups for Chikungunya infection?
A. Although the risk of serious disease is low, certain groups are at higher risk, including:
- Pregnant women
- People with weakened immune systems
- People suffering from severe chronic illness and the elderly
For more information refer to these websites:
National Vector Borne Disease Control Programme - www.nvbdcp.gov.in
National Institute of Communicable Diseases - www.nicd.org
Indian Council of Medical Research – www.icmr.nic.in
WHO India country office - www.whoindia.org
WHO SEARO – www.searo.who.int
WHO HQ - www.who.int
Centers for Disease Prevention and Control: USA – www.cdc.gov