vector-borne disease

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

Battle mosquitoes vigorously

India’s dengue deaths have long called for controlling mosquitoes through source reduction at breeding sites.

The WHO report describing the first Zika virus cases is important as it provides evidence of the virus circulating in India. While the Gujarat government says there’s no need to panic over the state’s three occurrences, it’s clear India must take greater precautions, more in areas where the Aedes mosquitoes are significantly present. The virus, which has no cure or vaccine but is not known to be deadly like dengue, was first found in India in 1964. It is known since 2015 that a virulent version, which swept the world and affected the Rio Olympics last year with some athletes withdrawing, could be headed for India as the more benign strain was within some people, and could prepare genetic grounds for the second coming.

Mosquito-borne diseases like malaria, dengue and chikungunya have taken more lives than other forms of pestilence. India’s dengue deaths have long called for controlling mosquitoes through source reduction at breeding sites. And yet the Gujarat CM took the pedantic line that there was no Zika patient in his state now as the three known cases were already treated. As none of the three had travelled abroad, it is likely the infection was picked up locally. However, the presence of Aedes aegypti and Aedes albopictus mosquitoes, which are active during daytime, and the general overcrowding, lack of hygiene and very warm summers are known to be grounds for an expanding threat. There has fortunately been no case yet of microcephaly (small head and brain in new-borns), but the war on mosquitoes must be fought with increased vigour.

Source: DECCAN Chronicle

Insects resist genetic methods to control disease spread, study finds

The research, reported in the journal Science Advances, combines advanced genetic and statistical analyses to show how certain genetic and behavioral qualities in disease-carrying insects, like mosquitoes, make these species resistant to genetic manipulation.

This resistance could complicate attempts to use CRISPR-Cas9 in the fight against malaria — a deadly mosquito-borne disease that threatens over 3 billion people worldwide — or crop blights such as the western corn rootworm, an invasive species that costs the U.S. about $1 billion in lost crops each year.

The discovery of the CRISPR-Cas9 system — or simply “CRISPR” — in the early 2010s introduced an unprecedented level of accuracy in genetic editing. Scientists can use the method to design highly precise genetic “scissors” that snip out and replace specific parts of the genome with sequences of their choosing. Two English scientists were the first to show the method could spread infertility in disease-carrying mosquitoes in late 2015.

“We found that small genetic variation within species — as well as many insects’ tendency to inbreed — can seriously impact the effectiveness of attempts to reduce their numbers using CRISPR technology,” said Michael J. Wade, Distinguished Professor of Biology at IU Bloomington. “Although rare, these naturally occurring genetic variants resistant to CRISPR are enough to halt attempts at population control using genetic technology, quickly returning wild populations to their earlier, ‘pre-CRISPR’ numbers.”

This means costly and time-consuming efforts to introduce genes that could control insect populations — such as a trait that causes female mosquitoes to lay fewer eggs — would disappear in a few months. This is because male mosquitoes — used to transmit new genes since they don’t bite — only live about 10 days.

The protective effect of naturally occurring genetic variation is strong enough to overcome the use of “gene drives” based on CRISPR-based technology — unless a gene drive is matched to the genetic background of a specific target population, Wade added. Gene drives refer to genes that spread at a rate of nearly 90 percent — significantly higher than the normal 50 percent chance of inherence that occurs in sexually reproducing organisms.

Wade, an expert in “selfish genes” that function similarly to gene drives due to their “super-Darwinian” ability to rapidly spread throughout a population, teamed up with colleagues at IU — including Gabriel E. Zentner, an expert in CRISPR-based genetic tools and assistant professor in the Department of Biology — to explore the effectiveness of CRISPR-based population control in flour beetles, a species estimated to destroy 20 percent of the world’s grain after harvest.

The team designed CRISPR-based interventions that targeted three segments in the genome of the flour beetle from four parts of the world: India, Spain, Peru and Indiana. They then analyzed the DNA of all four varieties of beetle and found naturally occurring variants in the targeted gene sequence, the presence of which would impact the effectiveness of the CRISPR-based technology.

The analysis revealed genetic variation in all four species at nearly every analyzed DNA segment, including a variance rate as high as 28 percent in the Peruvian beetles. Significantly, Wade’s statistical analysis found that a genetic variation rate as low as 1 percent — combined with a rate of inbreeding typical to mosquitos in the wild — was enough to eliminate any CRISPR-based population-control methods in six generations.

The results suggest that a careful analysis of genetic variation in the target population must precede efforts to control disease-carrying insects using CRISPR technology. They also suggest that the unintended spread of modified genes across the globe is highly unlikely since typical levels of genetic variation place a natural roadblock on spread between regions or species.

“Based on this study, anyone trying to reduce insect populations through this method should conduct a thorough genetic analysis of the target gene region to assess variation rates,” Wade said. “This will help predict the effectiveness of the method, as well as provide insight into ways to circumvent natural genetic variation through the use of Cas9 variants with an altered sequence specificity.”

Source: ScienceDaily

India unprepared for dengue, Chikungunya finds analysis.

India and other countries in South Asia are unprepared to address emerging vector-borne viral infections such as dengue and chikungunya, an analysis released by Centre for Disease Dynamics, Economics & Policy (CDDEP) on Wednesday revealed.

After examining vulnerability to emerging and growing infectious disease threats and the capacity to respond to outbreaks, the analysis finds the level of preparedness is inadequate to protect public health across the region.

The main burden of vector-borne viral infections in the South Asia region are dengue and chikungunya, while zika virus is also likely to emerge. Of the 390 million dengue infections that are estimated to occur annually worldwide, over 70 per cent occur in South Asia, the analysis noted. The report cites that in India, almost 95 per cent of adults by the age 40 have been infected with dengue virus, while 41 per cent have been infected with chikungunya.

At the heels of the report, JP Nadda, Union Minister for Health and Family Welfare, held a high level meeting to review the preparedness of the Ministry and central government hospitals for prevention and control of dengue and chikungunya in the country.

South Asia’s battles against viral diseases
Countries in South Asia region — Afghanistan, Bangladesh, Bhutan, India, Maldives, Nepal, Pakistan, and Sri Lanka, is home to a significant proportion of the global burden of infectious disease. Of the 390 million dengue infections that occur annually worldwide, over 70 per cent occur in South Asia

Longstanding battles
Tuberculosis, HIV, malaria, dengue, chikungunya

Emerging infectious diseases
Zika, ebola, MERS-CoV, avian influenza, neuroleptospirosis and leptospirosis, anthrax.

Source:DNA

India begins outdoor caged trials of genetically modified mosquitoes

India launched a project aimed at suppressing the local Aedes aegypti mosquito population by introducing genetically modified mosquitoes, according to two companies involved in the plan.

A similar project was approved last year in Florida on the heels of the Zika virus outbreak, which has been driven primarily by A. aegypti mosquitoes. Both projects involve so-called self-limiting male mosquitoes — brand name Friendly (Oxitec) — that are genetically modified to produce offspring that do not survive to maturity.

Five open field trials of the mosquitoes in Brazil, Panama and the Cayman Islands each led to a more than 90% reduction of the wild A. aegypti populations, according to a news release from the British company Oxitec and Gangabishan Bhikulal Investment and Trading Limited (GBIT), an Indian company. Open field trials are also planned for India, pending regulatory approval, the companies said.

For now, the India project was launched on Jan. 23 with outdoor caged trials in Dawalwadi. In these trials, the genetically modified mosquitoes are released into cages to mate with wild-type A. aegypti mosquitoes, Matthew Warren, spokesman for Oxitec, explained to Infectious Disease News. The results are then compared with cages where the mosquitoes were not released, Warren said.

In November, officials in Florida authorized a plan to use Oxitec’s modified mosquitoes in a field trial in Monroe County. The decision by the Florida Keys Mosquito Control District (FKMCD) came after residents, apparently reluctant about the method at first, voted to approve the idea.

An earlier survey showed that residents did not support the use of genetically modified mosquitoes as insect control, but the survey was conducted before the Zika outbreak became headline news and prior to an FDA report that said the mosquitoes would have no significant impact on human health, animal health or the environment.

Oxitec is currently deploying the mosquitoes in the Cayman Islands and Piracicaba, Brazil, but Warren said the trial in the Florida Keys is not yet underway.

“We are working with the FKMCD to identify a new site for the trial, and are gathering and submitting additional information to the FDA,” Warren said. “At this stage I don’t have a timeline, but we’re working to ensure that it is held in the most rigorous way possible and launched as promptly as the regulatory process will allow.”

While India is not among the 76 countries that have reported evidence of mosquito-borne Zika virus transmission since 2007, WHO has said that any country with a population of Aedes mosquitoes is at risk for transmission.

The primary aim of the project in India seems to be decreasing cases of dengue and chikungunya, which also can be spread by A. aegypti mosquitoes. According to estimates published in 2014, dengue infects an average of 5.8 million people each year in India at a cost of more than $1.1 billion. The country also has seen outbreaks of chikungunya, including some last year, according to the news release.

“Increasing cases of dengue and chikungunya have been reported in recent years,” Shirish Barwale, member of the board of directors at GBIT, said in the release. “Presently available methods have not been effective against these public health hazards. We are very optimistic that this pioneering technology from Oxitec will help us to control the mosquito responsible for spreading these diseases.” – by Gerard Gallagher

Source: Healio

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

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