Now, climate-based system could predict dengue spread in India

Agencies
September 3, 2017

London, Sept 3: Scientists have developed a system that can predict the spread of dengue in different parts of India, based on climatic factors, an advance that may help take preventive measures against the deadly infection.

Researchers from the University of Liverpool in the UK identified the climatic risks for dengue disease outbreaks in different climatic zones in the country through the states of Punjab, Haryana, Rajasthan, Gujarat and Kerala. The team, in collaboration with researchers from Indian Institute of Chemical Technology (IICT) in Hyderabad and National Institute of Pharmaceutical Education and Research

(NIPER) in Guwahati, focused on changes in a factor called 'extrinsic incubation period (EIP)' of the dengue virus by taking into account daily and monthly mean temperatures in these areas.

EIP is the time taken for incubation of the virus in the mosquito. During this period, after the mosquito draws a virus-rich-blood meal, the virus escapes the gut, passes through the mosquito's body and reaches it salivary glands. Once this happens, the mosquito is infectious and capable of transmitting the virus to a human host. It has been found that climatic conditions play an important role in EIP.

Lower temperatures (17-18 degrees Celsius) result in longer EIPs thereby leading to decreased virus transmission. With increasing temperatures, feeding increases because of enhanced metabolism of the mosquito, leading to shorter EIPs. Even a five-day decrease in the incubation period can hike transmission rate by three times, and with an increase in temperature from 17 to 30 degrees Celsius, dengue transmission increases fourfold.

However, a further increase in temperature beyond 35 degrees Celsius is detrimental to the mosquito survival. Researchers observed that except for Gujarat which comprises of arid regions, there was a strong correlation between rainfall and dengue disease burden.

They propose an increase in breeding grounds for mosquitoes as a major reason for this finding. The study found that Kerala being warm (temperature range 23.5-30 degrees Celsius) and wet and with short EIPs (9-14 days) experiences the highest number of dengue cases.

It has been found that EIP is the shortest during the monsoon season in most states and therefore there is an enhanced risk of dengue during this time. It is important to take into account the dynamic EIP estimates in different regions in assessing disease burden. "This climate-based dengue forecasting model could help health authorities to assess the disease intensity in a geographic region, based on that they can plan disease control operations well in advance and optimise the use of resources meticulously," said Srinivasa Rao Mutheneni of IICT, who led the study.

Changes in temperature affecting the extrinsic incubation period of the virus, future changes in the climate might have a substantial effect on dengue and other vector-borne disease burden in India.

"Though such methods are in vogue for disease control operations, we are still in the initial stages of implementation of such strategic control methods," Rao said. "Factors such as population density and migration also need to be included for future risk assessment studies," he said.

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Agencies
July 30,2020

New York, Jul 30: Can the coronavirus spread through the air? Yes, it's possible.

The World Health Organisation recently acknowledged the possibility that Covid-19 might be spread in the air under certain conditions.

Recent Covid-19 outbreaks in crowded indoor settings — restaurants, nightclubs and choir practices — suggest the virus can hang around in the air long enough to potentially infect others if social distancing measures are not strictly enforced.

Experts say the lack of ventilation in these situations is thought to have contributed to spread, and might have allowed the virus to linger in the air longer than normal.

In a report published in May, researchers found that talking produced respiratory droplets that could remain in the air in a closed environment for about eight to 14 minutes.

The WHO says those most at risk from airborne spread are doctors and nurses who perform specialized procedures such as inserting a breathing tube or putting patients on a ventilator.

Medical authorities recommend the use of protective masks and other equipment when doing such procedures.

Scientists maintain it's far less risky to be outside than indoors because virus droplets disperse in the fresh air, reducing the chances of Covid-19 transmission.

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Agencies
August 2,2020

Washington, Aug 2: Children under the age of five have between 10 to 100 times greater levels of genetic material of the coronavirus in their noses compared to older children and adults, a study in JAMA Pediatrics said Thursday.

Its authors wrote this meant that young children might be important drivers of Covid-19 transmission within communities -- a suggestion at odds with the current prevailing narrative.

The paper comes as the administration of US President Donald Trump is pushing hard for schools and daycare to reopen in order to kickstart the economy.

Between March 23 and April 27, researchers carried out nasal swab tests on 145 Chicago patients with mild to moderate illness within one week of symptom onset.

The patients were divided into three groups: 46 children younger than five-years-old, 51 children aged five to 17 years, and 48 adults aged 18 to 65 years.

The team, led by Dr Taylor Heald-Sargent of the Ann & Robert H. Lurie Children's Hospital, observed, "a 10-fold to 100-fold greater amount of SARS-CoV-2 in the upper respiratory tract of young children."

15 countries with the highest number of cases, deaths due to the Covid-19 pandemic

The authors added that a recent lab study had demonstrated that the more viral genetic material was present, the more infectious virus could be grown.

It has also previously been shown that children with high viral loads of the respiratory syncytial virus (RSV) are more likely to spread the disease.

"Thus, young children can potentially be important drivers of SARS-CoV-2 spread in the general population," the authors wrote.

"Behavioral habits of young children and close quarters in school and daycare settings raise concern for SARS-CoV-2 amplification in this population as public health restrictions are eased," they concluded.

The new findings are at odds with the current view among health authorities that young children -- who, it has been well established, are far less likely to fall seriously ill from the virus -- don't spread it much to others either.

However, there has been fairly little research on the topic so far.

One recent study in South Korea found children aged 10 to 19 transmitted Covid-19 within households as much as adults, but children under nine transmitted the virus at lower rates.

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Agencies
May 26,2020

Tedros Adhanom Ghebreyesus, the World Health Organisation's (WHO) Director-General, said that a clinical trial of hydroxychloroquine (HCQ) on COVID-19 patients has come to "a temporary pause", while the safety data of the the anti-malaria drug was being reviewed.

According to the WHO chief, The Lancet medical journal on May 22 had published an observational study on HCQ and chloroquine and its effects on COVID-19 patients that have been hospitalized, reports Xinhua news agency.

The authors of the study reported that among patients receiving the drug, when used alone or with a macrolide, they estimated a higher mortality rate.

"The Executive Group of the Solidarity Trial, representing 10 of the participating countries, met on Saturday (May 23) and has agreed to review a comprehensive analysis and critical appraisal of all evidence available globally," Tedros said in a virtual press conference on Monday.

The review will consider data collected so far in the Solidarity Trial and in particular robust randomized available data, to adequately evaluate the potential benefits and harms from this drug, he said.

"The Executive Group has implemented a temporary pause of the HCQ arm within the Solidarity Trial while the safety data is reviewed by the Data Safety Monitoring Board. The other arms of the trial are continuing," Tedros added.

WHO initiated the Solidarity Trial, a plan to evaluate the safety and efficacy of four drugs and drug combinations against COVID-19 more than two months ago, which include HCQ.

According to the WHO, over 400 hospitals in 35 countries are actively recruiting patients and nearly 3,500 patients have been enrolled from 17 countries under the Solidarity Trial.

Tedros added that the safety concern over the drug related only to the use of HCQ and chloroquine in COVID-19, and "these drugs are accepted as generally safe for use in patients with autoimmune diseases or malaria".

"WHO will provide further updates as we know more," he added.

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