An insect-borne virus has emerged in South America and two deaths were reported in two young Brazilian women due to the same. The women had no underlying health conditions. In June and July, Europe saw 19 imported cases of the Oropouche virus, as reported by the European Center for Disease Control. Spain accounted for 12 cases, Italy for five, and Germany for two.

The virus is primarily spread through insect bites, including mosquitoes, and midges and originates from pale-throated sloths, non-human primates, and birds, as per Newsweek. The symptoms include headaches, fever, muscle aches, stiff joints, nausea, vomiting, chills, and light sensitivity, which are similar to dengue fever. In extreme situations, the virus can enter the brain system and cause encephalitis, meningitis, and other potentially lethal neuroinvasive diseases. The Centers for Disease Control estimates that just 4 per cent of patients experience this.

The scientific journal Lancet Infectious Disease stated that the Oropouche outbreak this year has reached an “unprecedented scale.”

Currently, there is no vaccine available for the virus, which belongs to the same family of diseases as Zika virus and Dengue fever. According to the Centre for Disease Control, the incubation period for Oropouche virus disease is three to ten days. “Typically, disease starts with the abrupt onset of fever (38-40 degress Celcius) with headache (often severe), chills, myalgia, and arthralgia,” they added.

The symptoms of the disease can last up to seven days, however, they can reoccur a few days or even weeks later in about 60 per cent of patients. Further, weakness has been seen in several patients for up to a month following diagnosis.

Since midges are tiny insects that are less affected by typical repellents, common pest control methods like insect repellants and mosquito nets are not usually successful against them. However, chemical pesticides like DEET and deltamethrin work well against these insects.

Outbreaks of the virus have earlier been reported in countries across South and Central America, as well as the Caribbean. In 2024, outbreaks were recorded in Brazil, Bolivia, Colombia, Peru, and more recently in Cuba. Over 8,000 cases have been reported in Brazil, Bolivia, Peru, Colombia, and Cuba since the beginning of this year.

The virus got its name when it was initially discovered in the Trinidad and Tobago town of Oropouche in 1955. Even though there have been almost five lakh cases reported since then, not much is known about the illness.

A worker fumigating a private building surroundings to control mosquitoes and to prevent spread of dengue. File
| Photo Credit: K. Bhagya Prakash

Can the dengue virus beat the coronavirus and is it why the early wave of the pandemic in 2020 resulted in fewer COVID deaths or severe infections compared to Europe or North America where dengue is not endemic? Research from the CSIR-Indian Institute of Chemical Biology, Kolkata hints at these intriguing possibilities following an analysis of antibodies from people infected with dengue and testing them against a kind of coronavirus called murine hepatitis virus (mouse coronavirus). In research settings, this virus — being part of the same family of human coronaviruses — is considered a good surrogate to study the behaviour of the coronavirus strains that infected people during the pandemic.

Their results, published in the peer-reviewed Journal of Medical Virology this week, suggest that the antibodies following a dengue infection were able to ‘neutralise’ these coronavirus. For their analysis, the scientists relied on a combination of computer-modelling studies as well as cell-culture studies, the latter demonstrating how antibodies from dengue were able to engulf and bind the coronavirus proteins.

However, this protective effect did not necessarily expand to all coronavirus variants.

These latest studies build on the lab’s work from 2020 that blood tests specific to check for dengue sometimes led to a positive SARS-CoV-2 test.

“We experimentally demonstrated that serum samples from dengue patients have the potential to bind to and “mask” the surface of several coronaviruses, including SARS-CoV-2. We performed “virus neutralization” tests in cell cultures and showed that such “masking” by dengue antibodies can indeed, block coronavirus entry into susceptible cells,” Dr. Subhajit Biswas, Principal Scientist and the main author of the study, told The Hindu.

The dengue family of viruses are different from the coronavirus family and hence infection from one, in normal circumstances, is not expected to protect against the other. What is known about dengue is that there are four major serotypes, or strains, that cause dengue infections. Strains Denv-1 and Denv-2 are the most common in India. However, being infected with one does not protect against the other and, in fact, a re-infection involving a different strain can be more dangerous — a phenomenon called antibody-dependent enhancement (ADE) in dengue. Whether the prevalence of dengue in dengue-endemic countries of Southeast Asia may be triggering newer mutations in the coronavirus is a factor that needs to be investigated more extensively, the authors suggest in their study.

That the early stages of the pandemic saw a decline in dengue in India has been independently reported. The National Vector Borne Disease Control Programme of India reported a sharp decline of 75% (39,419 versus 1,57,315) in dengue incidence during 2020 as compared with 2019. “The possible reasons for this reduction could be lower transmission of the vector, less exposure due to COVID-19 lockdown, and, potentially, a disparity in the reported data possibly due to underdiagnosis or underreporting because of increased attention to the COVID-19 pandemic,” said a 2021 study in the American Journal of Tropical Medicine and Hygeine.

“In this paper, we provided several pieces of experimentally obtained evidence that pre-existing dengue immunity might have played some protective role in reducing the COVID severity and mortality in dengue-prone regions like Southeast Asia compared to regions where dengue does not occur frequently, like Europe and North America. Perhaps this is why, historically, human coronaviruses have been rarely encountered as a causative agent of “severe acute respiratory infections, SARI” from India, highly endemic for dengue virus,” he added.

The dilemma was whether the cross-reactive antibodies would provide partial protection against severe dengue infection or lead to increased severity due to the well-known phenomenon of antibody-dependent enhancement seen in dengue.  We hypothesize that the presence of antibodies to SARS-CoV-2 might decrease the severity of dengue. Larger multicentric clinical studies or population data from dengue endemic regions might help in understanding the existence of the cross-reactive, cross-protective association between these two single-stranded, positively coiled +SS RNA viruses.

Mumbai:

Maharashtra Deputy Chief Minister Ajit Pawar had been diagnosed with dengue and advised medical guidance and rest for the next few days, his party leader Praful Patel said on Sunday. Patel, who is the working president of a rival NCP group, took to X to inform about the health condition of 64-year-old Pawar.

“Contrary to speculative media reports suggesting that Ajit Pawar is not attending public events, I would like to clarify that he has been diagnosed with dengue since yesterday and has been advised medical guidance and rest for the next few days,” he said.

“Ajit Pawar remains committed to his public service responsibilities. Once he has fully recovered, he will be back in full force to continue his dedicated public duties,” Patel added in the post.

Contrary to speculative media reports suggesting that Shri Ajit Pawar is not attending public events, I would like to clarify that he has been diagnosed with dengue since yesterday and has been advised medical guidance and rest for the next few days. Shri Ajit Pawar remains…

— Praful Patel (@praful_patel) October 29, 2023

On July 2 this year, Ajit Pawar along with eight other senior NCP leaders joined the Eknath Shinde-led state government, leading to a split in the party founded by his uncle Sharad Pawar.

Ajit Pawar claims to have the support of more than 40 of the 53 NCP MLAs in the state. 

(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)

Patna:

Bihar is witnessing an alarming rise in dengue cases, with 6,146 cases reported in September, the highest for the month in the last five years, according to the health department’s data.

The state had reported 6,421 cases this year, of which 6,146 were reported only in September, three times the 1,896 registered in September last year.

As many as 416 cases were reported in the state on Friday, with Patna recording the most at 177, followed by Munger at 33, Saran (28), Bhagalpur (27) and Begusarai (17).

According to the National Center for Vector Borne Disease Control of the Union Health Ministry, seven dengue deaths have been reported in Bihar till September 17 this year.

As per the health department’s data, a total of 13,972 cases were reported last year.

As many as 295 people were undergoing treatment at 12 government hospitals till September 30, including 127 at Jawaharlal Nehru Medical College and Hospital in Bhagalpur, 39 at VIMS in Pawapuri and 28 at Patna Medical College and Hospital.

Dr Manoj Kumar, a renowned medical practitioner in the state, told PTI, “There is no need to panic as dengue cases always increase during this season. Keeping homes and surroundings dry and clean and body covered helps curb the spread of the disease. Mosquito repellants and nets must be used and all possible breeding sites should be detected and eliminated.” Patna District Magistrate Chandrasekhar Singh said the administration is keeping a close watch on a daily basis and spraying and fogging are being conducted, while awareness camps on vector borne diseases are also being organised.

Patna Municipal Corporation (PMC) Commissioner Animesh Kumar Parashar said the civic body has launched an extensive drive to check the increasing number of dengue cases in the city.

“Chemical fogging is being carried out with the help of 140 vehicles and hand-held devices. We have constituted 375 teams for fogging operations. Residential premises that have reported dengue cases recently are regularly sanitised,” he said.

(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)

A mosquito hangs from a leaf, Bengaluru, October 28, 2019.
| Photo Credit: Syed Ali/Unsplash

Throughout human history, mosquitoes have constantly buzzed in the background of human existence, irritating us with their incessant bites and occasionally wreaking havoc by transmitting deadly diseases. The earliest known mosquitoes from the fossil record date back at least 70 million years, and evidence of mosquito-borne diseases like malaria dates back to Egyptian mummies from 2000 BC.

Apart from malaria, which claims the lives of over half a million people every year and infects close to 250 million, mosquitoes serve as vectors for various other diseases. These include dengue, Zika, lymphatic filariasis, and yellow fever. Understandably, our relationship with these tiny, blood-sucking insects has been far from cordial.

Help from sequencing tech

The rapid urbanisation of the world’s populations, especially in many large and economically developing countries like India, has led to annual surges in mosquito-borne illnesses like dengue. Together with climate change and its cascading consequences, mosquito-borne diseases have expanded into new territories. A notable example is the indigenous cases of dengue in France in recent years.

It is not surprising then that mosquito control has taken centrestage today and the battle continues unrelenting with an array of tools – from mosquito nets to insecticides and the use of symbionts like Wolbachia. But with insecticide resistance in mosquitoes rising to alarming proportions, it has become imperative that newer approaches to mosquito control gain prominence, even despite the availability of a first-generation malaria vaccine that officials in different countries are currently implementing in a pilot in endemic regions.

In the last two decades, our ability to read or sequence the genomes of organisms, and edit and manipulate these genomes, has given us new tools in this fight. Thanks to advancements in next-generation sequencing techniques, we now have access to the whole genome sequences of multiple mosquito species. Notably, researchers from the University of California, the Tata Institute of Genetics and Society, and the Institute of Bioinformatics and Applied Biotechnology have helped prepare high-quality reference genomes for Anopheles stephensi, a major malaria-vector mosquito. (The two latter institutes are based in Bengaluru.)

The availability of these high-quality sequences, coupled with our capacity to genetically manipulate them, offers unprecedented opportunities.

The gene drive

The fundamental idea behind genetic manipulation of mosquitoes is to systematically control their populations by interfering with their reproduction. Scientists worldwide have developed various genetic modification approaches. A major one in this endeavour is gene-drive technology, whose end result is for mosquitoes to selectively inherit some genes, rather than the inheritance to follow the rules of Mendelian genetics.

This technology was conceived by Austin Burt, professor at Imperial College London, in a 2003 paper published in Royal Society Proceedings. Here, a protein cuts the mosquito’s DNA at a part that doesn’t encode a particular sequence in the genome. This triggers a natural mechanism in the cell containing the DNA to repair it and forces the cell to incorporate a sequence, called the drive sequence, into the damaged portion.

Numerous gene-drive versions are documented in the literature, but they all focus on reducing mosquito populations’ reproductive capabilities or rendering them sterile. As a result, the malaria parasite won’t be able to replicate inside the mosquito’s gut. In a recent paper in Science Advances, researchers at Imperial College London genetically enhanced a gene expressed in the midgut of mosquitoes to secrete two antimicrobial substances called magainin 2 and melittin. They are detrimental to the Plasmodium parasite’s development in the midgut and also reduce the lifespan of female mosquitoes. Computational modelling studies have suggested that this approach could significantly disrupt malaria transmission.

Benefits as well as risks

In 2020, the U.S. Environmental Protection Agency authorised the release of a genetically modified mosquito called OX5034 in counties in Florida and Texas. Oxitec developed this mosquito with a gene sensitive to an antibiotic, tetracycline. The authorisation followed extensive field trials conducted by the company in Brazil. Genetically modified male OX5034 mosquitoes mated with female mosquitoes but the self-limiting gene prevented female offspring from surviving. As a result, the male mosquitoes would disappear from the environment after around a dozen generations.

Genetically modified mosquitoes have been used in outdoor but controlled conditions in India, Brazil, and Panama as well. Early results from these trials showed promising drops in mosquito populations, around 90% during the trials. Additional trials have shown that such technologies can decrease incidence of dengue significantly as well.

These technologies can bring benefits as well as risks, in different ways. An immediate implication is that the drastic reduction in the mosquito population could alter food chains and ecosystems that involve mosquitoes. So it’s likely that the gap in the food chain could be ‘invaded’ by other mosquitoes or in fact other insects. As such, we don’t fully understand the implications in the short and longer terms. And since the consequences will be shared by individuals, communities, and populations, in that order, what constitutes a right decision and what processes are to be followed remains a dilemma to policymakers.

A timeless struggle

It is therefore not surprising that the genetic engineering of mosquitoes and trials involving genetically modified mosquitoes have faced multifaceted challenges in different parts of the world. Critics have expressed concerns about unintended consequences, such as unforeseen ecological disruptions or the potential for engineered genes to spread beyond target mosquito populations.

Some of these concerns are valid and require extensive data collection, close monitoring, and multistakeholder discussions surrounding the adoption of this technology. Closer home, on the regulatory front, the Department of Biotechnology released comprehensive guidelines for genetically engineered insects earlier this year. They provide a roadmap for researchers, outlining procedures and regulations for working with such insects in the country.

The battle between mosquitoes and humankind seems to be a timeless struggle, a testament to human ingenuity against frustrating troublemakers aided by evolution.

The authors are senior consultants at the Vishwanath Cancer Care Foundation.