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Tag Archive for: yellow fever

What a mosquito’s immune system can tell us about fighting malaria

What a mosquito’s immune system can tell us about fighting malaria

Immune cells in a malaria-transmitting mosquito sense the invading parasites and deploy an army of tiny messengers in response. These couriers help turn on a mosquito’s defenses, killing off the parasites, a new study suggests.

This more detailed understanding of the mosquito immune system, published January 20 in Science Immunology, might help scientists design new ways to combat malaria, which infects more than 200 million people per year.

“If we understand how the mosquito reduces the parasite to begin with, we hope we can boost these mechanisms to completely eliminate these parasites [in mosquitoes],” says Kristin Michel, an insect immunologist at Kansas State University in Manhattan who wasn’t part of the study.

Different parasites in the Plasmodium genus cause malaria. The disease is spread by certain Anopheles mosquitoes. These mosquitoes have natural defenses against Plasmodium that keep them from being overrun with the parasites when feeding on an infected person’s blood. But malaria transmission still occurs, because some Plasmodium species are particularly skilled at evading mosquito immune systems.

Previous research has shown that hemocytes, the insect equivalent of white blood cells, help mosquitoes fight off pathogens. Carolina Barillas-Mury and her colleagues at the National Institute of Allergy and Infectious Diseases in Rockville, Md., injected Anopheles gambiae mosquitoes — a primary spreader of malaria in sub-Saharan Africa — with a dye that stained their hemocytes. Those mosquitoes snacked on mice infected with a rodent version of malaria. Then the scientists watched the dyed hemocytes’ response.
Parasite’s problem

Sensing the presence of a malaria-causing parasite, mosquito immune cells (teal) kill themselves and release microvesicles (red) that activate cellular machinery that fights off the parasites, a new study finds.

Hemocytes that detected certain chemical fingerprints left by the parasites began to self-destruct. These dying hemocytes released plumes of tiny vesicles that then activated the mosquito’s defenses against the parasite, the researchers found. The vesicles triggered a protein called TEP1 to take down the parasite. Scientists already knew that TEP1 is an important part of mosquitoes’ immune response against Plasmodium parasites, but it wasn’t clear how the protein was called into action. Without the vesicles, TEP1 didn’t target the parasites.

Barillas-Mury and colleagues don’t know exactly what the microvesicles contain. But she suspects they carry messenger molecules that jump-start TEP1 and other proteins involved in this immune response.

This type of response “is a very powerful defense system because it can make holes in the parasite and kill it,” says Barillas-Mury. “You want it to be active, but in the right place and at the right time.” Plasmodium parasites set up shop in different places in the mosquito gut depending on their life stage. Microvesicles, much smaller than the hemocytes, can more easily move through different gut compartments to trigger a localized immune response right where the parasite is.

The researchers eventually hope to use their understanding of the mosquito immune response to develop new ways to stop malaria. They’re interested in creating a vaccine that prevents mosquitoes that bite an infected person from passing along the parasite. Such a vaccine could be used in combination with others under development that would prevent people infected with the parasite from becoming sick, Barillas-Mury says.

Source: Sciencenews.org

Here are some important facts about Dengue and Chikungunya

Here are some important facts about Dengue and Chikungunya

In a recent report, the MCD has confirmed as many as 2,711 dengue cases till October 8 as the situation remains critical.

New Delhi: Dengue and chikungunya have struck fear in Delhi so much that the health graph of the city has registered a steep rise in these cases of late.

In a recent report, the MCD has confirmed as many as 2,711 dengue cases till October 8 as the situation remains critical across the country.

With these vector-borne diseases, characterised by high fever and severe pain in the joints, taking their toll on our lives, experts have listed down some of the misconceptions about them that have been setting off false alarm bells around the country and undermining the efforts to curb and control these ailments.

1. Dengue and chikungunya mosquitoes breed in dirty water: This is the most common misconception associated with dengue and chikungunya. It is not just dirty water that mosquitoes can lay eggs in; clean water that has been stagnant for over five days can also often act as the best breeding ground for Aedes aegypti, the yellow fever mosquito. Discarded tyres and tubes, empty flower pots, water stored in drums and water collected under refrigerators after defrosting can all be potential breeding havens for mosquitoes.

2. Having dengue once means it will not occur again: There are four different types of dengue viruses namely DEN 1, 2, 3 and 4. Being affected by one of the four types offers no protection against other strains, which means much like common flu, dengue can be contracted multiple times by a patient over the course of his/her lifetime.

3. Antibiotics are needed to treat dengue and chikungunya: So far, there is no vaccine that can immunise human beings against these diseases but vaccine for dengue will be coming soon. Nearly 75 percent of dengue cases are curable just by properly dispensing oral fluids and providing proper care and treatment to patients. Only prevention and control of mosquitoes can ensure long-term protection against these diseases.

4. Low platelet count does not always mean dengue: People tend to associate low platelet count with dengue. While it is a good indicator to find out if a patient is suffering from dengue or not, a common cold and viral fever can also bring down your platelet count. There are several other viral infections which can result in a low platelet count; people diagnosed with blood-related diseases, anaemia, severe infections and immunological disorders are bound to have fewer platelets in their blood.

5. Using insecticide sprays is enough to kill mosquitoes: While sprays and fumigation can prove beneficial in curbing the mosquito population to a great extent, using only insecticides cannot ensure 100 percent safety against mosquitoes. The main reason for this is mosquitoes get killed but eggs and larvae don’t get killed. It is equally important to keep your surroundings clean and tidy. Vectors are born in stagnant water accumulated in coolers, air conditioners, pots, ornamental plants, fountains, water tanks, bird feeders, etc. Hence, it is important to maintain hygiene in and around the house, and not allow water to accumulate anywhere.

6. Chikungunya will lead to joint deformity: While symptoms of chikungunya include joint pain and muscle pain, and can closely mimic rheumatoid arthritis or other rheumatologic diseases, the vector-borne disease cannot deform your joints. Most patients recover fully but in some cases, the joint pains may persist for weeks or months.

Given the rapid rise in the number of reported cases of dengue and chikungunya, it is essential for every individual to contribute in the fight against these deadly diseases and to keep India healthy and illness-free. Accurate information, coupled with proper preventative measures, can play a major role in achieving this aim and ensure a tomorrow free from the threat of dengue and chikungunya.

Source: Deccan Chronicle News

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