dengue viruses

Beware of repeated dengue afflictions

Docs Warn That Fatality Risk Increases Due To Reaction Between Antibodies Present In The Body From Primary & Secondary Infections
Even as dengue ravages Kerala, health experts are confused by the uncommon traits and complications that were recently observed in patients.

The pattern of dengue deaths also indicates that mortality rate was high among patients who were repeatedly diagnosed with the disease.

If a person gets dengue for the first time (type-I), proper rest and medication will help in combating fever and antibodies will be generated in the body that will give life-long immunity against the type-I variety. But, when the same person is exposed to mosquito bites and gets dengue (type-II or type-III), a new set of antibodies will be generated in the body. Antibodies generated in the primary infection and secondary infection react, resulting in grave complications that may even lead to the death of the patient.

Through virus uptake and replication, type-I antibodies will intensify and complicate the typeII virus by a process called antibody dependent immune enhancement. “When a person is tested positive for dengue, prescribed antibiotics will only treat the symptoms of fever and not the virus.Like any other viral fever, dengue virus will subside and antibodies will be generated in a week. When a person is affected by dengue twice or thrice, the reaction of subsequent antibodies will lead to internal bleeding and cause dengue haemorrhagic fever or dengue shock syndrome that may lead to death,” said associate professor of community medicine at Thiruvananthapuram medical college Dr Althaf A.

The scattered information and diagnoses are yet to be compiled and analysed by authorities. Sources in the health department said there was no proper database or research on such complexities.

“When autopsy was conducted in a suspected case of dengue death in 2013, we found that the person was suffering from West Nile fever, a mosquito-borne disease. Similarly , all reported deaths might not be due to dengue. We are unable to contain deaths as scientific analysis and research are lacking,” said Dr Althaf.

There are four different strains of dengue and for a person repeatedly afflicted with dengue, the risk factor goes up. “Severe internal bleeding or blood loss can occur due to the reaction of antibodies already present in hisher body . This is a matter we have to address through research,” said former state nodal officer (communicable diseases) Dr Amar Fettle.

Genetic mutation in disease causing virus is also suspected to be one of the major reasons for the increase in fatalities, said experts. “The spontaneous changes in genetic coding of dengue causing virus can be one of the reasons for the complications.Similar to the mutation seen in H1N1 virus, dengue causing virus is suspected to have undergone genetic mutation. H1N1 virus was seen only in animals at first, it later it was transmitted to humans and by 2008, due to mutation, H1N1 virus was transmitted from one human to another,” said Dr Althaf.

Doctors, who treat dengue, have also no ticed the change in symptoms. “Many patients who seek treatment for diarrhoea; throat pain and vomiting are later diagnosed with dengue. The symptoms were high fever, back and abdominal pain. It is not the same now,” said a doctor at the general hospital in the capital on condition of anonymity .

“The Aedes aegypti mosquitoes are responsible for the outbreak.These mosquitoes can cause chikungunya, yellow fever and Zika fever.Our environment is very receptive to these diseases and we are vulnerable,” he said.

Dengue cases have risen in Thiruvananthapuram, Kollam, Alappuzha, Palakkad, Malappuram and Kozhikode this year and the disease has become round-the-year problem over the past three years.

Source: THE TIMES OF INDIA

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

Scientists create mosquitoes resistant to dengue virus

Mosquitoes get infected when they feed on someone who has the disease. Then they pass dengue to healthy people by biting them.

Each year, dengue sickens about 96 million people worldwide. The virus kills more than 20,000 people, mostly children, the researchers said.

“If you can replace a natural population of dengue-transmitting mosquitoes with genetically modified ones that are resistant to virus, you can stop disease transmission. This is a first step toward that goal,” said study leader George Dimopoulos, a professor of molecular microbiology and immunology at Hopkins.

The genetic modifications significantly increased the mosquitoes’ resistance to dengue. But the changes didn’t boost the mosquitoes’ defenses against Zika or chikungunya viruses.

“This finding, although disappointing, teaches us something about the mosquito’s immune system and how it deals with different viruses. It will guide us on how to make mosquitoes resistant to multiple types of viruses,” Dimopoulos said in a Hopkins news release.

He and his team said more research and testing is needed before these dengue-resistant mosquitoes are introduced into the wild, a process they said could take a decade or more.

Forty percent of the world’s population live in areas where they are at risk for dengue infection, the study authors said. The virus is most common in Southeast Asia and the western Pacific islands. But dengue infections have been increasing in Latin America and the Caribbean.

The research was published Jan. 12 in the journal PLOS Neglected Tropical Diseases.

Source: UPI

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 in Mumbai highest in 6 years

MUMBAI: The number of dengue cases recorded in the city this year has been the highest in the last six years. However, the good news is that fatalities have declined significantly over the last three years.

According to figures recently released by the state, Mumbai has recorded 1,088 cases so far this year and four confirmed deaths. The last time dengue cases had crossed the 1,000mark was in 2012. Within the state too, the highest number of cases were reported from the city. Dengue infected 6,376 people and claimed 26 lives in Maharashtra between January 1 and November 21this year. Doctors say the increase in incidence is a reason for concern as it can lead to longer hospital stays, lost manhours and bigger hospital expenses. “Dengue causes mortality in merely 1%-3% of cases. It is the morbidity that needs to be looked into closely,” said infectious disease consultant Dr Om Srivastava. He said that patients this ye ar had complained of pro blems in resuming their routine lives long after they had recovered from the mosquitoborne illness.

A senior physician from KEM Hospital in Parel too added that patients came to the hospital three months after recovering from the disease with complaints of lethargy . “In a few cases, the symptoms had persisted from six weeks to three months,” the doctor said. Srivastava added that many patients fail to follow the post-recovery regimen like drinking water and taking adequate rest which prolong their suffering.

Source: Times Of India

Dengue Claimed 179 Lives, no Death Due to Chikungunya: Government

Dengue has claimed 179 lives across the country this year while no death has been reported due to chikungunya, though it affected 21,000 people, the Rajya Sabha was told today.

“During 2016 (till November 13), a total number of 179 deaths due to dengue and no death due to chikungunya has been reported in the country.

“The number of positive cases for dengue and chikungunya in the country during 2016 (till November 13) are 90,277 and 21,094 respectively,” Health Minister J P Nadda said in a written reply.

He said the reason behind the steep increase in the number of cases are– water storage practices, poor solid waste management, construction activities, large migratory population, inadequate vector management and lack of protective immunity in the affected population.

Dengue claimed 33 lives in Uttar Pradesh, 28 in West Bengal and 22 in Maharashtra, he said. Replying to another question on the same issue, Minister State for Health Faggan Singh Kulaste said the government has taken measures for prevention and control of dengue and chikungunya in the country, including in Delhi.

He said technical guidelines for prevention and control, clinical management and vector control have been issued to states and UTs while periodic reviews have taken place.

Since January, 2016, 22 review meetings at the levels of Minister, secretary and others were held.

He said since January 12 advisories have been issued at the levels of Secretary (H&FW) and Additional Secretary while states were requested to declare dengue as notifiable disease.

“States were requested to curtail out of pocket expenditure by fixing the rate for testing at Rs 600,” he said.

He said dengue and chikungunya diagnosis is provided through 542 Sentinel Surveillance Hospitals (SSHs) and 15 Apex Referral laboratories (ARLs) identified across the country.

“First version draft of ‘Strategy and Plan of action for Effective Community Participation for Prevention and Control of Dengue’ has been uploaded. A user-friendly App ‘India Fights Dengue’ has been launched while National Dengue Day has been observed on May 16, 2016 throughout the country,” he said.

Source : Smartcooky

School children work on project to fight dengue

BERHAMPUR: At a time when the state is grappling with dengue, students of MM High School, Girishola here have prepared a project to fight the disease.

The project has suggested plantation of marigold, lemon grass and podina (meant) sapling on open spaces of the villages and houses to drive away the mosquito species like aedes and anopheles responsible for diseases like dengue, malaria and chikungunya.

The project ‘Killer dengue in Girishola – a case study, remedy and solution’ has been prepared by five students of Class VIII with active guidance of the science teacher Raghunath Ghadei. It has been selected for National Children’s Science Congress (NCSC) to be held at Vidya Pratishthan’s Institute of Information Technology (VIIT), Baramati, in Maharashtra from December 27 to 31.

The project also suggested development of culture centres of dragonfly and Gambusia fish to prevent increase of mosquito population. “While we have experimented by planting the marigold herbs on the premises of our school, we came to know from the elder persons about the role of dragonfly to kill the small mosquitoes during the preparation of the project,” said P Veketesh, a student involved in the project.

The fragrance of the herbs of marigold, lemon grass and meant can prevent entry of mosquitoes to a particular area, said the guide of the project. Other students, who participated in the preparation of the project, are Rahul Moharana, Balaram Sahu, Asish Moharana and Shankar Pradhan while science supervisor Gopal Krushna Panda was actively involved in the experiments.

While a single dragonfly can eat over 30 mosquitoes a day, its larva also gulps the larva of mosquito, said Ghadei. Similarly the Gambusia fish also eats the larva of mosquito. The students of the high school mooted the project after 200 people were affected by dengue killing six persons in Girishola in July and August.

The team members toured the village and interacted with several victims to know their garbage disposal method. The village along Odisha-Andhra Pradesh border has no space for garbage disposal as the NH-16 passes in one side while railway track is on the other side. In other two sides, there are state highways. The school students along with villagers took 15 days to clean the garbage.

Times of India

Cities account for 60% of state’s dengue casualties this year

MUMBAI: Around 60% of dengue deaths in the state this year have been reported from urban areas. An analysis of the confirmed cases by the state’s health department also revealed that nearly two-thirds of the positive cases were from the urban areas.

The Mumbai Metropolitan Region, Pune, Nashik and Aurangabad have reported nearly 70% of the 5,391 dengue cases this year. The state’s figures also show a 63% jump in dengue cases between January and October this year when compared with the corresponding period last year. Out of the 22 deaths this year, 13 have been reported from the urban areas.

Mumbai alone has reported nearly 1,000 cases and four confirmed cases. However, more than 10,000 people have been hospitalised during monsoon for suspected dengue or similar illnesses. Speaking to TOI, head of the directorate of health services Dr Satish Pawar said, “It is particularly worrying because only 40% of our population resides in the urban areas. But, we have found out that construction activities are not the sole reason for the growing incidence of dengue. In certain cases where dengue had become complicated, doctors have used aggressive treatment where it was not required. Some of these hospitals were in big cities”.

Pawar added that the state has drawn up uniform treatment protocols and even trained doctors but the indiscriminate use of platelets continues to be an issue. The BMC had, in an analysis last year, found out that the use of platelets rose by 14-15% during months when dengue peaked in the city. This year, however, the situation was much better. A civic official said the use of platelets during dengue was closely monitored. “This year, there was no unusual demand for platelets,” the official said.

Times of India

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

Dengue threat spirals out of hand as Kolkata’s platelet count drops

Kolkata: An acute platelet crisis has hit the city in the midst of a fresh dengue spurt, holding up treatment of patients in serious conditions. With blood donation camps dwindling in the festive period, supply of platelets has almost dried up. Consequently, all major blood banks are facing a crisis that isn’t going to ease till December.

Bhoruka Blood Bank, one of the prominent private banks in Kolkata, has been out of stock since Sunday. It isn’t expecting fresh supplies till next Sunday when donation camps are due. Life Care Bank, too, has no platelet but is helping dengue patients in case the latter’s kin donates blood. “We are getting the donated blood processed and giving out the platelet content. But the process is expensive and takes several hours,” said a spokesperson for the bank. While a unit of platelet sells for Rs 500, the processing charge could be as high as Rs 8000-10000.

At Ashok Blood Bank, stocks have been getting exhausted within hours of donation camps. They, too, have the facility to extract platelets from donated blood which takes around five hours. “For several weeks now, we have not been able to hold stocks for more than six hours,” said a representative.

Demand for platelets has gone up almost four times across city hospitals, forcing them to ration use. But planned camps and an organized system could help avert crises, felt Rupali Basu, CEO of Apollo Gleneagles Hospital where 17 have succumbed to dengue since July. “We insist on sticking to an exchange system for patients who need transfusion. Patients’ kin must donate blood. This has ensured that we never run out of stock,” said Basu. She added that blood banks needed to be more pro-active in organizing camps. “They can’t afford to rely on clubs and organizations alone. During festive periods, a crisis is invariably going to strike since camps will be fewer. A system needs to be evolved to tide over shortages like this,” she said.

At least two city hospitals said they were rationing platelet use, even though it may put patients’ lives to risk. Lion’s Blood Bank has been flooded with calls ever since it tied up with a club that will hold a camp on Thursday. “Mid-week supplies have been dwindling sharply, leaving patients’ families helpless. We have been able to organize the camp with a lot of difficulty. But the platelets are going to run out by Friday,” said an official.

TheTimesOfIndia