severe pain in joints

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

Behavioral Resistance: Mosquitoes Learn to Avoid Bed Nets

Malaria is a notoriously tricky infectious disease. Because of a unique genetic flexibility, it is able to change surface proteins, avoiding the immune response and greatly complicating vaccine development. Furthermore, the parasite is transmitted by mosquitoes, which are difficult to control. Insecticides work, but mosquitoes can develop resistance to them.

One method widely used to control malaria is for governments or charities to provide families with insecticide-treated bed nets. Overall, this strategy is very successful, and it has been credited with preventing some 451 million cases of malaria in the past 15 years. But bed nets are not successful everywhere. In some parts of the world, mosquitoes develop “behavioral resistance”; i.e., they learn to avoid bed nets by biting people earlier in the day.

A team led by Lisa Reimer of the Liverpool School of Tropical Medicine monitored mosquito behavior in villages in Papua New Guinea before (2008) and after (2009-2011) the distribution of bed nets. Data from one of the villages, Mauno, depicts a very noticeable shift in mosquito feeding behavior.

Before bed nets were distributed in 2008, the median biting time for mosquitoes was around midnight. After the distribution, the median time shifted back to 10 pm. Also, a greater proportion of mosquitoes took their dinner even earlier, from 7 to 9 pm.

Worryingly, it’s unclear whether the bed nets were effective at preventing malaria transmission. The number of bites per person per night dropped after the introduction of bed nets, but started to climb in subsequent years as mosquitoes began to adapt. Additionally, the prevalence of malaria infection in humans — arguably, the only statistic that actually matters — dropped in one village, remained the same in a second, and ticked up slightly (albeit insignificantly) in a third.

Despite the mixed results in Papua New Guinea, Dr Reimer believes that bed nets should continue to be used worldwide as part of a mosquito control strategy. However, she notes that behavioral resistance may prove just as vexing as insecticide resistance and, in some locations, may limit the efficacy of bed nets.

Thus, mosquitoes must be monitored for both behavioral and insecticide resistance, as the little creeps stubbornly refuse to die and may be cleverer than we thought.

Source: Edward K. Thomsen et al. “Mosquito behaviour change after distribution of bednets results in decreased protection against malaria exposure.”

Source : Acsh.org

Dengue cases grew by 63% in Maharashtra this year

The number of dengue cases in Maharashtra rose 63% between January and October this year compared to the same period last year. The number of deaths have remained the same, with 22 deaths in the comparative periods for 2015 and 2016.

Dengue is transmitted by the aedes aegypti-species of mosquito and has become a major public concern in the past two months, doctors said. A total of 5,653 cases were reported by the state epidemiology department this year as compared to 3,461 cases last year, with cases coming from cities like Mumbai, Kalyan-Dombivli, Pune and Nashik, said Dr Kanchan Jagtap , joint director of health services of the state.

“Every year, there is an increase in the number of dengue cases post monsoon. Moreover, the increase in construction sites have created an ideal environment for mosquito breeding,” she said.

Although the number of dengue cases has gone up, not everyone who is infected with the virus develops complications, said doctors. “Say out of 100 people infected with dengue, only 10 show complications such as a drop in blood pressure, severe drop in n platelet counts, ”said Dr Pradeep Shah, physician, Fortis Hospital, Mulund.

“Most of the patients who show complications are people who have had dengue in the past, young children, elderly and pregnant women. These are the vulnerable groups,” he said.

Doctors also said state data could be giving an incomplete picture of the dengue situation, because only those cases where the patient has tested positive for dengue infection using the ELISA (enzyme-linked immunosorbent assay) method of testing are counted as confirmed. “We treat so many patients who have all symptoms of dengue infection, but their blood test reports for ELISA test are negative. These numbers are not accounted for in the state’s data,” said Dr Altaf Patel, director of medicine Jaslok Hospital.

October 2016

Kalyan-Dombivali Municipal Corporation

Number of cases 63 number of deaths 5

Mira-Bhayander Municipal Corporation

Number of cases 33 number of deaths 2

Brihanmumbai Municipal Corporation

Number of cases 941 number of deaths 2

Source : Hindustantimes.com

Florida’s Fight Over GM Mosquitoes Going to a Vote

Scientists say there is strong evidence that the Zika virus can be controlled by releasing genetically modified male mosquitoes into the wild so they can mate with the disease-spreading females to produce sterile offspring.

But plans for a trial run in Key Haven, Fla., an unincorporated community just east of Key West, have been so controversial that officials decided to put it to a public vote.

Tuesday’s referendum is non-binding, but will weigh heavily on whether the Florida Keys Mosquito Control District proceeds with the test, which was approved by the U.S. Food and Drug Administration in August.

The genetically modified mosquitoes have been tested in Brazil, Panama and the Caymen Islands, where they reduced the wild population of Zika-bearing Aedes aegypti mosquitoes by more than 90 percent, according to British biotechnology company Oxitec, which developed the engineered strain of mosquitoes.

“In comparison, current technologies such as insecticides are only 30-to 50 percent effective at best,” Oxitec spokesman Matthew Warren told Seeker.

In addition to the Zika virus, which can cause birth defects and other disorders, Aedes aegypti mosquitoes are responsible for the spread of dengue and chikungunya. It’s the female mosquitoes that do the biting, spreading disease in their wake.

Oxitec’s solution is to engineer a gene in the males, which are then released into the wild so they can mate with the females. Any offspring that result from the union will carry an engineered “kill switch” and die before maturing enough to mate or bite, drastically reducing the population.

“We have now released more than 180 million of our male self-limiting mosquitoes worldwide. And there have been no reports of adverse impacts in any of these releases,” Warren said.

The trial in the Florida Keys would be the first in the United States.

“The genetically modified mosquitoes are incredibly promising. They’ve been incredibly successful in many of the cases where they’ve been tested for Zika so far. I think that they have tremendous promise in the United States, but there are obviously a lot of fears,” ecologist Colin Carlson, with the University of California, Berkeley, told Seeker.

Among those opposed to the Florida trial is a group of physicians, led by Dr. John Norris, who have questions about whether Oxitec’s mosquitoes, which are dependent on the antibiotic tetracycline to survive, will end up spreading antibiotic-resistant bacteria.

“We do not know what to expect when millions of mosquitoes are released on small neighborhoods possibly covered in resistant germs,” the doctors wrote in a petition to the Florida Keys Mosquito Control Board.

If the board decides to proceed with the trial, the doctors want to conduct a study to see if residents have altered bacterial resistance patterns.

Whether the referendum passes or not, one thing is certain: the spread of the Zika virus in South Florida is growing.

“We’re still trying to figure out how severe it’s going to be,” Carlson said. “From a public health perspective, it’s not a great situation.”

Pending approval by the Florida Keys Mosquito Control District, Oxitec’s test could begin next year.

Seeker.com

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