Mosquitoes and Malaria Ecology

Mosquitoes and Malaria : 

Mosquitoes and Malaria Mausi and Cinry

Mosquitoes and health : 

7/30/2008 Template copyright 2005 www.brainybetty.com 2 Mosquitoes and health Mosquitoes are a vector agent that carries disease-causing viruses and parasites from person to person without catching the disease themselves. Female mosquitoes suck blood from people and other animals as part of their eating and breeding habits. When a mosquito bites, she also injects saliva and anti-coagulants into the blood which may also contain disease-causing viruses or other parasites. This cycle can be interrupted by killing the mosquitoes, isolating infected people from all mosquitoes while they are infectious or vaccinating the exposed population.

Mosquitoes and health contd. : 

7/30/2008 Template copyright 2005 www.brainybetty.com 3 Mosquitoes and health contd. Mosquitoes are estimated to transmit disease to more than 700 million people annually in Africa, South America, Central America, Mexico and much of Asia with millions of resulting deaths. In Europe, Russia, Greenland, Canada, the United States, Australia, New Zealand, Japan and other temperate and developed countries, mosquito bites are now mostly an irritating nuisance; but still cause some deaths each year. Historically, before mosquito transmitted diseases were brought under control, they caused tens of thousands of deaths in these countries and hundreds of thousands of infections

What is Malaria? : 

7/30/2008 Template copyright 2005 www.brainybetty.com 4 What is Malaria? Malaria [muh-LARE-ee-uh] is a long-lasting disease of the blood. It is transmitted to people by mosquitoes infected with the malaria parasite. The malaria parasite attacks the blood and causes recurring chills, fever, and sometimes jaundice and anemia. Malaria is very common throughout the world. In the Developed Countries, the main risk is to persons traveling to tropical and subtropical countries where malaria is a problem. No vaccine against malaria is available. Travelers can protect themselves by using anti-mosquito measures and by taking drugs to prevent malaria.

Types of Malaria : 

7/30/2008 Template copyright 2005 www.brainybetty.com 5 Types of Malaria

What is the infectious agent that causes malaria? : 

7/30/2008 Template copyright 2005 www.brainybetty.com 6 What is the infectious agent that causes malaria? Malaria is caused by any one of four species of one-celled parasites, called Plasmodium. The parasite is spread to people by the female Anopheles mosquito, which feeds on human blood. Although four species of malaria parasites can infect humans and cause illness, only malaria caused by Plasmodium falciparum is potentially life-threatening.

Where is malaria found? : 

7/30/2008 Template copyright 2005 www.brainybetty.com 7 Where is malaria found? Malaria transmission occurs in large areas of Central and South America, sub-Saharan Africa, the Indian subcontinent, Southeast Asia, the Middle East, and Oceania. The risk to travelers varies depending on local weather conditions, the number of mosquitoes in the area, and the traveler's itinerary and time and type of travel.

How is malaria spread? : 

7/30/2008 Template copyright 2005 www.brainybetty.com 8 How is malaria spread? A person gets malaria from the bite of an infected female mosquito. The mosquito bite injects young forms of the malaria parasite into the person's blood. The parasites travel through the person's bloodstream to the liver, where they grow to their next stage of development. In 6 to 9 days, the parasites leave the liver and enter the bloodstream again. They invade the red blood cells, finish growing, and begin to multiply quickly. The number of parasites increases until the red blood cells burst, releasing thousands of parasites into the person's bloodstream. The parasites attack other red blood cells, and the cycle of infection continues, causing the common signs and symptoms of malaria.

How is malaria spread? Contd. : 

7/30/2008 Template copyright 2005 www.brainybetty.com 9 How is malaria spread? Contd. When a non-infected mosquito bites an infected person, the mosquito sucks up parasites from the person's blood. The mosquito is then infected with the malaria parasites. The parasites go through several stages of growth in the mosquito. When the mosquito bites someone else, that person will become infected with malaria parasites, and the cycle will begin again. Malaria parasites can also be transmitted by transfusion of blood from an infected person or by the use of needles or syringes contaminated with the blood of an infected person.

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What are the signs and symptoms of malaria? : 

7/30/2008 Template copyright 2005 www.brainybetty.com 11 What are the signs and symptoms of malaria? People with malaria typically have cycles of chills, fever, and sweating that recur every 1, 2, or 3 days. The attack of the malaria parasites on the person's red blood cells makes the person's temperature rise and the person feel hot. The subsequent bursting of red blood cells makes the person feel cold and have hard, shaking chills. Nausea, vomiting, and diarrhea often go along with the fever. The destruction of red blood cells can also cause jaundice (yellowing of the skin or whites of the eyes) and anemia.

Slide 12: 

7/30/2008 Template copyright 2005 www.brainybetty.com 12 How soon after exposure do symptoms appear? The time between a mosquito bite and the start of illness is usually 7 to 21 days, but some types of malaria parasites take much longer to cause symptoms. When infection occurs by blood transfusion, the time to the start of symptoms depends on the number of parasites in the transfusion.   How is malaria diagnosed? Malaria is diagnosed by a blood test to check for parasites. Who is at risk for malaria? Anyone who lives in or travels to a country where there are malaria-infected people and mosquitoes is at risk.   What complications can result from malaria? Malaria caused by Plasmodium falciparum can cause kidney or liver failure, coma, and death. Although infections with other malaria parasites cause less serious illness, parasites can remain inactive in the liver and cause a reappearance of symptoms months or even years later.

Slide 13: 

7/30/2008 Template copyright 2005 www.brainybetty.com 13 What is the treatment for malaria? The treatment for malaria depends on where a person is infected with the disease. Different areas of the world have malaria types that are resistant to certain medicines. The correct drugs for each type of malaria must be prescribed by a doctor. Infection with Plasmodium falciparum is a medical emergency. About 2% of persons infected with falciparum malaria die, usually because of delayed treatment.   How common is malaria? Worldwide, an estimated 200 million to 300 million malaria infections occur each year, with 2 million to 3 million deaths. Most deaths are from infection with Plasmodium falciparum. About 1,200 cases of malaria are diagnosed in the United States each year. Most are in persons entering the country for the first time or returning from foreign travel. A very small number of cases are the result of direct transmission involving mosquitoes that live in the United States. Most of these have occurred in Mexican farm workers living in California in poor conditions.

Is malaria an emerging infectious disease? : 

7/30/2008 Template copyright 2005 www.brainybetty.com 14 Is malaria an emerging infectious disease? Yes. Many countries have been experiencing a resurgence in cases caused by Plasmodium falciparum, the most deadly of the four human malaria parasites. Urban migration, poverty, and poor sanitation have returned malaria to cities where it once was eliminated. New roads, logging, and irrigation have drawn people into once-isolated areas where mosquitoes thrive. Refugees, migrants, and tourists have spread the disease across borders.

Effects of Natural Selection in the re-emergence of Malaria : 

7/30/2008 Template copyright 2005 www.brainybetty.com 15 Effects of Natural Selection in the re-emergence of Malaria The seriousness of the worldwide re-emergence of malaria is made worse by the spread of parasites that are resistant to anti-malaria drugs. Parasites, like bacteria and viruses, can develop resistance to the drugs used to prevent or treat infection. Malaria parasites are increasingly resistant to chloroquine, the drug most widely used for prevention and treatment. Chloroquine-resistant strains have been reported from areas in Africa, Asia, and the Americas. More and more mosquitoes have also developed a resistance to anti-mosquito room sprays and anti mosquito creams that make it even more difficult to prevent certain spread of disease not necessarily just malaria.