An outbreak of dengue fever in Yemen’s most populated governorate has prompted urgent calls from the World Health Organisation (WHO) for a “humanitarian corridor” to facilitate the flow of medicines to over three million civilians trapped in the war-torn area.

Taiz, located on the country’s southern tip, has been on the frontline of fighting between Houthi rebels and a Saudi Arabia-backed coalition of Arab states supporting fighters loyal to deposed President Abd-Rabbu Mansour Hadi since March 2015.

Three of Taiz’s major hospitals have either been destroyed or are inaccessible, leaving 3.2 million people – many of them sick or injured – without access to basic healthcare.

An estimated 832 people in the governorate have died and 6,135 have been wounded since the war broke out.

To make matters worse, in the past two weeks alone the number of suspected dengue cases has nearly tripled from 145 cases in early August to nearly 421 by the month’s end.

As the conflict escalates with both sides showing little regard for civilian safety, the WHO fears that the health situation will deteriorate in the coming months, worsening the misery of people caught between Houthi gunfire and Coalition airstrikes.

In a statement released on Aug. 27, WHO Regional Director for the Eastern Mediterranean Ala Alwan said: “All parties to the conflict must observe a ceasefire and demilitarize all hospitals and health facilities in Taiz, allow for the safe delivery of the supplies, implement measures to control the dengue outbreak, provide treatment and enable access to injured people and other patients.”

A mosquito-borne disease caused by the dengue virus, this tropical fever causes flu-like symptoms including high temperatures and muscle pains.

If symptoms are not quickly identified and managed, the patient may experience dangerously low platelet counts, internal bleeding or low blood pressure. Undetected, the disease can be fatal.

Mosquitoes carrying the virus thrive in stagnant water, and dengue epidemics often spread quickly in densely populated areas where open sewer systems or uncollected garbage provide convenient homes for the larvae.

With huge numbers of displaced Yemenis living in cramped and unsanitary makeshift settlements, it is small wonder that the disease is moving so rapidly.

The WHO’s most recent situation report for Yemen reveals that the country has logged over 5,600 suspected cases of dengue fever since March, including 3,000 cases in the coastal city of Aden alone.

Incomplete levels of medical reporting as a result of heavy fighting suggest that the real number of cases could be much higher.

Children are more likely than adults to develop the severe form of the disease, known as the Dengue Haemorrhagic Fever. With children accounting for over 600,000 of the nearly 1.5 million displaced in Yemen, health officials are on red alert.

Since there is no vaccine against the diseases, and no specific antiviral drug with which to treat the symptoms, prevention is the only long-term solution.

The WHO is partnering with other organisations and local health authorities to distribute insecticide-treated mosquito nets, educate families on the causes of the diseases, conduct indoor spraying to disrupt breeding grounds and secure necessary laboratory supplies for medical facilities.

These tasks are not easily accomplished in the midst of relentless air strikes and heavy fighting.

“We need protection and safety for all people working to control the worrying outbreak of dengue fever in Taiz,” the WHO said today, adding that parties to the conflict must stay mindful of their obligations under international law to protect medical facilities and health personnel during war-time.

Edited by Kitty Stapp

Schoolchildren hold up a handmade sign that reads: ‘Let’s Eradicate Dengue’. Credit: Amantha Perera/IPS

By Amantha Perera
COLOMBO, Jun 30 2014 (IPS)

What’s the connection between weather forecasts and the mosquito-borne dengue virus? It’s not just a question for science nerds; in Sri Lanka, health officials believe answering this question could save lives.

For over half a decade now, doctors and residents of this island nation, especially those living in the cramped Western Province, have been battling the persistent, sometimes deadly, dengue plague, which tends to follow the monsoon rains that drench the southwest coast from June to October.

The tropical disease generally results in prolonged fever, muscle and joint pains, as well as skin rashes. In a small number of cases, the disease turns into the life-threatening dengue hemorrhagic fever, characterised by bleeding, low levels of blood platelets, or dangerously low blood pressure, which can send the victim into shock, sometimes triggering fatalities.

“When we have better forecast data, we [will] be able to correlate the disease distribution in various parts of the island and make a feasible disease map that can be used for the whole country." -- Faseeha Noordeen, head of the department of microbiology at the University of Peradeniya
In mid-2009, soon after the annual monsoon, dengue infections increased at an alarming rate across Sri Lanka. By the end of the year, 35,095 people were infected, while the number of fatalities stood at 346.

The impact of the epidemic can be gauged by comparing current infection rates with the last dengue outbreak, which was recorded in 1989, a year that saw 200 infections and around 13 deaths.

Since 2009 the number of infections has been steadily high; they have never fallen below 28,000, while the highest number of infections – 44,461 – was reported in 2012.

While fatalities have been brought down – there were 83 deaths in 2013, the same year that logged 32,000 infections – dengue experts and medical professionals say there is an urgent need for a comprehensive management plan to curtail the impact of the disease.

“We need a much more stringent prevention regime,” Nimalka Pannilahetti, a consultant community physician at the National Dengue Control Unit, told IPS.

It is not that Sri Lanka has been lax on tackling mosquito breeding grounds; in fact it has initiated everything from a Presidential Task Force on Dengue Prevention, to fines for those who neglect possible breeding grounds, to declaring national dengue eradication programmes.

Unfortunately, the combined result of these projects is that the rate of infection is exactly what it was five years ago, or – in areas where slight reductions are reported – still alarmingly high.

The situation is especially worrying in the Western Province, home to over 25 percent of the country’s population of over 20 million people, and to 60 percent of all reported dengue cases since 2009.

Enter the forecasters

Given that so many strategies have been tried and failed, experts are now suggesting that the authorities call in help from the national Meteorological Bureau as the latest weapon in the fight against the virus.

Faseeha Noordeen, head of the department of microbiology at the University of Peradeniya in central Sri Lanka, told IPS that there is a clear connection between changing climate patterns and the spread of dengue.

In a research paper she co-authored, published in the International Journal of Infectious Diseases in October 2013, Noordeen said that mosquito breeding grounds increased following heavy rains, pointing out that the two annual peaks in infections were recorded soon after the two annual monsoons.

Noordeen’s research also found that warming weather patterns increased the distribution of the dengue-carrying mosquito. She believes that detailed weather forecasts could help health authorities to better allocate resources and strategically implement prevention campaigns.

“When we have better forecast data, we [will] be able to correlate the disease distribution in various parts of the island [and] make a feasible disease map that can be used for the whole country,” she said.

Pannilahetti agrees, stressing that detailed forecasts would be “invaluable” for people like her, who are tasked with hunting a species of mosquito that is constantly on the move, and eradicating a disease that is constantly changing.

“Right now we are following the rains,” she said. “Preemptive programmes could be much more effective.”

Midway through June the Prevention Unit was scrambling to relocate most of its resources to the Western Province, which absorbed the heaviest rains in the first week of this month.

The third of week of June, meanwhile, saw the launch of a massive dengue eradication programme that included members of the armed forces, Pannilahetti added.

Some regions of the province received four to six times their average June rainfall in the first week of the month this year. Pannilahetti said that detailed forecasts would have enabled health officials to raise their levels of preparedness beforehand.

Greater risks for low-income communities

She added that the burden of the disease is unevenly distributed between the rich and poor, since the spread of dengue is largely determined by the cleanliness of the immediate environment, and a community’s proximity to receptacles like tanks of stagnant water, or even accumulated garbage.

“What we have seen is that there are more breeding grounds in low income areas, where people tend to pay less attention to how safe or healthy their immediate environment is,” Pannilahetti said.

Additionally, medical treatment comes at a high price, often leaving the poor without access to quality care.

LakKumar Fernando, who heads the Centre for Clinical Management of Dengue and Dengue Hemorrhagic Fever at the Negombo Government Hospital, 35 km north of the capital Colombo, says that dengue can be successfully treated if detected early.

“The first thing is to get a blood test done,” he told IPS; but doing so costs about 2,000 rupees (about 15 dollars) at private clinics, a sum that many people in this country cannot afford.

In a bid to make the process more accessible, the government recently set up six new blood testing centres in government hospitals across the Western Province, but these alone will not be able to tackle the hundreds of cases coming in every single day, according to experts.

The unit that Fernando heads has been recognised as one of the best treatment facilities in the country, with only a single fatality out of 1,180 cases admitted since June 2013.

“We never let our patients go into shock, we monitor them round the clock,” Fernando said, adding that the most effective treatment for dengue was constant monitoring of blood pressure, pulse and urine output while maintaining a good fluid intake.

But the cost of setting up the unit, where each of the 17 beds is equipped with state-of-the-art monitoring equipment, was about 100 million rupees, or 750,000 dollars, hardly the kind of initiative that can be easily replicated around the country.

In fact, units like the one in Negombo are few and far between in Sri Lanka’s public health system, which makes an even stronger case for developing solid prevention systems, experts say.

(END)

People go about their daily lives in Roseau, Dominica. The country’s chief medical officer says climate change is taking a toll on the health of people. Credit: Desmond Brown/IPS

By Desmond Brown
ROSEAU, Dominica, Jan 20 2014 (IPS)

Caribbean countries, struggling to emerge from a slump in exports and falling tourist arrivals brought on by the worldwide economic crisis that began five years ago, have one more thing to worry about in 2014.

Dominica’s chief medical officer, Dr. David John, said climate change and its effects are taking a toll on the health of people in his homeland and elsewhere in the region.“A lot of diseases will essentially create havoc among people who are already poor." -- Dr. Lystra Fletcher-Paul

“You have seen what is happening [with] the effects of climate change in terms of our infrastructure, but there are also significant effects with regards to climate change on health,” John said, adding that “these effects relate to the spread of disease including dengue fever and certain respiratory illnesses.”

John said the Dominica government would be seeking assistance from international agencies, including the World Meteorological Organisation (WMO), to mitigate “the effects of climate change on health as it relates to dengue, leptospirosis and viral disease.”

In late 2012, the Ministry of Health in Barbados alerted members of the public about a spike in leptospirosis cases. Senior Medical Officer of Health-North Dr. Karen Springer said then that five people had contracted the severe bacterial infection, bringing the number of cases for the year to 18.

Springer explained that the disease, which includes flu-like symptoms such as fever, headache, chills, nausea and vomiting, eye inflammation and muscle aches, could be contracted through contact with water, damp soil or vegetation contaminated with the urine of infected animals. Bacteria can also enter the body through broken skin and if the person swallows contaminated food or water.

In recent years, dengue has also been on the rise throughout the Caribbean with outbreaks in Dominica, Barbados, Trinidad and Tobago, Puerto Rico and the French islands of Martinique and Guadeloupe, among other places.

Professor of environmental health at the Trinidad campus of the University of the West Indies Dr. Dave Chadee told IPS there is ample “evidence that climate-sensitive diseases are being tweaked and are having a more significant impact on the region”.

He said he co-authored a book with Anthony Chen and Sam Rawlins in 2006 which showed “very clearly” the association between the changes in the seasonal patterns of the weather and the onset and distribution of dengue fever.

“There is enough evidence, not only from the Caribbean region but worldwide, that these extreme events are going to have and going to play a significant role in the introduction and distribution of these sorts of diseases in the region,” Chadee, who previously served as an entomologist at the Insect Vector Control Division of the Ministry of Health in Trinidad and Tobago, told IPS.

“If you look at the various factors that are associated with climate change, the first is heat waves. There has also been a reduction in air quality. You also see an increase in fires and the effects on people’s ability to breathe as well as the association between the Sahara dust and asthma which was demonstrated in Barbados and Trinidad recently.

“The Sahara dust which comes in from Africa brings in not only the sand but also other pathogenic agents within the sand, together with some insecticides which have been identified by people working at the University of the West Indies,” Chadee told IPS.

Dr. Lystra Fletcher-Paul, the Food and Agriculture Organisation (FAO) representative for Guyana, said she has no doubt that climate change has contributed significantly to some of the issues related to diseases in the region.

“If you look at some of the impacts of climate change, for example drought, with drought you are going to increase the amount of irrigation that you are going to be applying to the crops. And irrigation water is a source of pesticides or even chemicals, depending on where that source of water is and that could lead to problems in health,” she told IPS.

“Similarly with the extreme events, if you are talking about floods, there can be contamination of the fresh-water supply.”

The FAO representative is adamant that there is too much “talk” in the Caribbean and too little “implementation”.

“We have had the conversation, so what we need to do now is put the systems in place to mitigate and adapt to climate change,” she said. Using land-use planning as an example, Fletcher-Paul told IPS, “A lot of what we see happening in St. Vincent and St. Lucia may not necessarily have taken place if we had proper land-use planning.”

A slow-moving, low-level trough on Dec. 24 dumped hundreds of millimetres of rain on St. Vincent and the Grenadines, St. Lucia and Dominica, killing at least 13 people. The islands are still trying to recover.

“So we need to take some hard decisions in terms of where we would allow development to take place or not,” Fletcher-Paul said.

Chadee said the poor would always be at a disadvantage in  climate change scenarios and they will suffer the most from sea level rise when you have salt water intrusion into fertile agricultural land, rendering them unsuitable for food production.

“A lot of diseases will essentially create havoc to people who are already poor. The adaptability of the poor versus the rich within the Caribbean region will be tested because if the poor are no longer able to produce some of their food, this would then lead to health problems.”

He explained that if the poor are no longer able to have a particular diet this would make them susceptible to a number of diseases.

“With the Caribbean region having developing states, and especially Small Island Developing States, we do have a unique situation where the resources have to be put in place, especially for adaptation,” Chadee told IPS.

“It’s almost like the wall of the reservoir has been breached and you know that the water is coming. You don’t know how high the water level is going to be but you know it’s coming, so what do you do? And that essentially is the scenario in which we have found ourselves in the Caribbean,” Chadee added.

Honiara’s rapid urban growth and increased urban waste have become the focus of municipal efforts to stem the spread of dengue fever. Credit: Catherine Wilson/IPS

By Catherine Wilson
HONIARA, Solomon Islands, May 15 2013 (IPS)

City and health authorities in the Solomon Islands, located in the southwest Pacific Ocean, are calling for effective and consistent urban waste management as they battle to control a serious outbreak of dengue fever, the world’s fastest spreading vector-borne viral disease, which was identified in the country in February.

This archipelago nation of more than 900 forest-covered islands, lying just east of Papua New Guinea, has since recorded over 4,200 suspected and over 1,000 confirmed cases, with six fatalities. The outbreak has impacted eight of nine provinces in the country of 552,000, with 88 percent of cases located in the capital, Honiara.

According to Dr. Tenneth Dalipanda, under-secretary for health improvement and chairman of the national dengue fever task force, the crisis has not yet peaked and the country is still in “active outbreak mode.”

Dengue fever is an infectious tropical virus transmitted to humans by the bite of female mosquitoes, which breed in clean, warm water. In urban and semi-urban areas, gutters, old tyres, plastic containers and refuse – in short, any items that have become water receptacles in close proximity to households – make excellent hatcheries for dengue-carrying mosquito larvae.

In the Solomon Islands dengue is associated predominantly with the Aedes albopictus and Aedes aegypti mosquitoes, which bite during the day. The incubation period of the virus is typically four to 10 days, with symptoms including fever, headaches, nausea, a body rash and joint and muscle pain.

According to the World Health Organisation (WHO), the global incidence of dengue has grown 30-fold during the past 50 years, reaching an estimated 50 million infections every year. Transmission of the disease is particularly rapid in high-density urban areas in tropical and sub-tropical climates, where mosquitoes proliferate during monsoonal seasons or following periods of heavy rainfall.

But according to Dalipanda, a dengue outbreak of this magnitude has never been seen in the Solomon Islands before.

A small outbreak of “type 2” dengue in 2002 resulted only in a very small number of cases, he told IPS.

“The current outbreak is the first in the country that we have a record of and the strain that we now have is a type 3 dengue virus, which is one of the more virulent,” he explained, adding there are some 500 cases per 10,000 residents in Honiara.

The capacity of the nation’s health services has been under strain and the main National Referral Hospital located in Honiara was closed to routine services until last week, as resources were diverted to cope with the disease emergency.

The government has established a national task force to coordinate a response to the outbreak, with Australia and New Zealand providing teams of specialised medical and public health staff to assist local authorities.

There is no known cure or vaccine for dengue, making prevention critical. So in March the government spearheaded a citywide cleanup campaign in Honiara to try and contain breeding sites.

Through a public awareness programme, households, businesses and residents across the city were advised on how to clear accumulated solid waste such as tin cans, coconut shells, plastic bags and containers, used tyres, buckets and tin drums, and instructed to remove or cover water containers.

Honiara City Council Chief Health Inspector George Titiulu told IPS he had “longstanding” concerns about waste management and public health in the capital, since there is a strong link between the disease and urban refuse.

“The key mosquito breeding sites are (those areas) where the city’s waste collection services do not currently reach,” Titiulu said, referring to residential areas on the city’s periphery.

Population expansion coupled with rapid urbanisation in small Pacific Island nations has created major waste disposal challenges for the region.

Hand in hand with Honiara’s expansion has come an increasing volume of solid waste from shops, offices, markets and residential areas, while informal settlements mushrooming on the city’s boundary have now exceeded the capacity of service providers.

Thirty-five percent of the city’s population of 64,600, which is growing at an average annual rate of 2.7 percent, live in unplanned communities that have inadequate power, sanitation and garbage collection services, as well as a poor water supply.

The waste burden is even greater in the absence of recycling facilities in Honiara, although some agents collect aluminium cans for foreign recycling companies. The majority of organic, recyclable household waste, together with a great deal of plastic, is either burnt, discarded in coastal and land areas, or collected for landfill sites.

Acknowledging that the cleanup campaign likely prevented a steep increase in dengue cases, Dalipanda still feels its impact has not been adequate. “We would like to see the (incidence of cases) coming down.”

He confirmed that it was vital to continue vector-control measures such as managing and eliminating waste, covering water storage containers and applying insecticides, but warned that these should not be “one-off activities”.

“Different communities, institutions and ministries should become involved, because it is the only way we can break the cycle of the disease,” he emphasised.

The challenge has been taken up by the Honiara City Council, which recently submitted a 960,000-dollar proposal to the government to implement a comprehensive, yearlong garbage collection programme.

“This will be an integrated approach to waste management to include the cleaning of drains where rubbish collects, mass spraying and the social mobilisation of communities,” Titiulu elaborated.

“We want to work with those communities where services don’t reach and engage especially with youth to implement a (full-scale) cleanup of the city.”

But he stressed that the council, which currently only has three vehicles, will need funds, equipment and logistical support in order to carry out the plan.  If successful, it could disrupt the breeding momentum of the mosquitoes and reduce the likelihood of outbreaks in the near future.

A contaminated stream in Kimicanga, a suburb of Kigali, Rwanda. What if human and other waste could be turned into an energy and revenue-producing bio-gas? Credit: Aimable Twahirwa/IPS

By Stephen Leahy
UXBRIDGE, Canada, Apr 30 2013 (IPS)

One, two or more of the 102 newly launched out-of-the box ideas to improve global health could be world-changing breakthroughs.

It might be someone’s idea to create a test strip you touch with your tongue to see if you have a deadly disease. Or a mobile phone game to prevent HIV. Or the idea that untreated human waste from slums could be turned into marketable products.

Breakthroughs can’t happen without a genius idea and the opportunity to see if it works, said Dr. Peter Singer, CEO of Grand Challenges Canada.

“The health challenge is global but opportunities to pursue unconventional ideas is not,” Singer told IPS.

Grand Challenges Canada just announced grants of 100,000 dollars for 102 imaginative new ideas to tackle health problems in resource-poor countries. Of these, 59 grants went to researchers in 13 low- and middle-income nations worldwide.

“I was in Tanzania recently and young researchers there had great, off-the-wall ideas but no one thought they’d ever have a chance to pursue them,” he said.

Global Challenges Canada not only provides funding, it often acts as a mentor and helps set up partnerships with researchers in Canada. “Sometimes it’s just a matter of building self-confidence in their idea,” Singer said.

Although the 102 ideas are selected through a peer-review process, at this early point they aren’t much more than inspired ideas. No public or private organisations are interested in investing at such an early unproven stage.

Singer calls this the “pioneering gap” and hopes to create an “innovation pipeline” that one day will improve the health of people in their country.

“Maybe a few of these will become household health products one day,” he said.

If any of these raw ideas prove effective, the innovators will be eligible for an additional Grand Challenges Canada scale-up funding of up to one million dollars. The government of Canada funds the programme and is committing roughly 10.9 million dollars to support a portfolio of projects that could transform the way disease is treated in the developing world through the Grand Challenges Canada Stars in Global Health programme.

“We are pleased to work with our like-minded partners around the world to support global innovation and entrepreneurship that help produce better, brighter futures for people around the world,” said Canada’s Foreign Affairs Minister John Baird.

In Uganda, almost all human waste is discharged into streams, rivers and lakes, causing huge health problems. What if human and other waste could be turned into an energy and revenue-producing bio-gas?

Corinne Schuster-Wallace of U.N. University’s Canadian-based Institute for Water, Environment and Health is working with two Canadian companies to use large underground tanks to mulch human waste along with fish market refuse and other organic trash. Methane from the tanks will be tapped for a new economical source of fuel.

A sanitation system for 400,000 people in Kampala’s urban slums could operate on the profits from selling the biogas, a recent study showed. (Video of Schuster speaking about the project)

Another Ugandan project involves the development of a paper-strip test for the rare but deadly Ebola and Marburg viruses. The highly infectious nature of both diseases makes them major global threats. They are very hard to detect in the early stages, said project leader Dr. Misaki Wayengera of the Makerere University College of Health Sciences. (Video clip of Dr Wayengera talking about his project)

A similar test strip is being developed to test for dengue, often called “breakbone fever”, which afflicts up to 100 million people in tropical climates, said Ken Simiyu, a programme officer at Grand Challenges Canada. Early detection and treatment makes a huge difference in the outcome.

The idea is that a 10-cent strip of plastic-coated gold nanoparticles in combination with a 10-dollar hand-held device will be able to detect the disease, Simiyu told IPS.

Brazilian-born Dr. Alexandre Brolo of the University of Victoria, Canada has developed the test strip and will be testing it in Brazil. (Dr. Brolo talks about his innovation)

A less high-tech approach to improving global health is the proposed “sugar daddy” game for mobile phones. It’s a role-playing game to raise awareness about HIV’s dangers among girls and anticipate propositions from “sugar daddies”, said Simiyu.

Led by Dr. Njambi Njuguna of Kenyatta National Hospital, Kenya, the programme will send HIV-related mobile phone text messages to young females, many of whom do not perceive themselves to be at risk and thus don’t test. In Kenya, 84 percent of HIV-infected people are unaware of their status, with 33 percent untested because they don’t perceive a risk to themselves. (Dr. Njuguna talks about her bold idea)

Mobile phones could also provide real-time public health data from remote regions such as Nepal’s mountainous rural Achham district northwest of Kathmandu. Harvard researcher Duncan Maru, MD, PhD and a team of rural practitioners plan to help remote, rural community health workers use mobile phones to upload and publish data on both illness and local public health care capacity. (Dr. Maru talks about this first real-time surveillance system)

Getting this kind of real-time data is extremely important in both prevention and in designing effective public health programmes, said Singer.

“Beverage companies know exactly how many bottles they sold today. But in most of the world, we don’t know how many children died today,” he said. “If we don’t measure we can’t act.”

An Aedes aegypti mosquito, which transmits the dengue virus, feeding. Credit: jentavery/CC-BY-2.0

By Fabiana Frayssinet
RIO DE JANEIRO, Jan 10 2013 (IPS)

Mosquitoes that transmit dengue fever need clean, still water and warm night temperatures to reproduce and thrive. That is common knowledge, but now scientists in Brazil have managed to measure the relation between increased rainfall and temperatures and the risk of dengue epidemics in this city.

A study at the National School of Public Health in Rio, titled “Temporal analysis of the relationship between dengue and meteorological variables in the city of Rio de Janeiro, Brazil, 2001-2009” and published in the journal Cadernos de Saúde Pública, evaluated the relationship between climate variables and dengue risk.

The results showed that for the period 2001 to 2009, an increase of one degree in the minimum temperature in a given month led to an increase of 45 percent in reported dengue cases in the following month in Rio de Janeiro.

An increase of 10 millimetres in rainfall was associated with a lower rise of six percent in dengue virus infections in the following month.

“The relationship between rainfall, heat and tropical diseases is partly common sense. In our study we tried to provide a scientific explanation and a theoretical model to quantify this relationship,” Adriana Fagundes Gomes, one of the authors of the study at the School of Public Health, part of the private Oswaldo Cruz Foundation (FIOCRUZ), told IPS.

“The hypothesis was proven by mathematical methods,” said Gomes, who is currently a researcher in the epidemiology department of the Paulo de Góes Institute of Microbiology at the state Federal University of Rio de Janeiro (UFRJ).

Analysis of the data led to the conclusion that the risk of dengue increases when temperatures are above 26 degrees Celsius, as higher temperatures favour the development of the Aedes aegypti mosquito that transmits the dengue virus.

Average annual precipitation in Rio de Janeiro is about 1,000 millimetres, with the heaviest rainfall from December to March – the southern hemisphere summer – contributing to the proliferation of the mosquito vectors.

“It’s important to point out that the findings of this research paper have been known for a  long time: the mosquito needs clean water and high temperatures to reproduce, which is why summertime is the period of highest incidence of dengue fever,” Dr. Alberto Chebabo, a specialist in infectious diseases, told IPS.

“The only new result in this study was the measurement of how many new dengue cases per degree Celsius or per millimetre of rainfall there were during the epidemic years,” said Chebabo, head of the department of infectious and parasitic diseases at the Clementino Fraga Filho Hospital at UFRJ.

The study cross-compared data for: notifications of dengue cases from the Rio de Janeiro Secretaria Municipal de Saúde (SMS, Health Department); temperature from the Instituto Nacional de Pesquisas Espaciais (INPE, National Space Research Institute); and rainfall from the Secretaria Nacional de Obras Públicas (Municipal Department of Public Works).

Given the lack of a vaccine against dengue fever, the study authors say that increasing knowledge about how the virus develops will boost prevention.

“Establishing an early intervention system based on variables that can indicate the onset of an epidemic would reduce the risk of disease,” said Gomes.

“Studies of climatic variables can improve knowledge and prediction of epidemic seasonality, because the vector-climate relationship is just as important as vector-human interaction,” the study says.

In Gomes’ view, the main discovery is that, in Rio de Janeiro, temperature (especially minimum temperature) “has a more significant correlation with the number of dengue cases than rainfall.”

The Aedes aegypti mosquito needs clean water, from rainwater or irrigation, to lay its eggs. But high temperatures “facilitate hatching of the eggs and reduce the time needed by larvae to develop into adults,” said Chebabo.

“In the hot, rainy season of the Rio de Janeiro summer, mosquito numbers increase, enabling transmission of the disease,” he said.

Analysis of the last decade shows that in southeastern Brazil, where Rio de Janeiro is located, dengue is prevalent between the months of December and April, precisely the hottest and wettest period. All the epidemics of dengue fever have occurred within this period of the year.

The Aedes aegypti mosquito transmits dengue fever by picking up the virus when it feeds on the blood of an infected person, and infecting other people when it bites them. The symptoms are fever, headache and muscle pain. But haemorrhagic dengue causes intense abdominal pain, nausea and bleeding under the skin and into mucous linings, which can be fatal.

In Chebabo’s view, traditional methods of prevention carried out by “the human vector” – the agency of humans – are still essential for combating dengue.

“Eliminating mosquito breeding sites is the most effective means of reducing incidence of the disease,” he said.

The government and the population must work together to get rid of water accumulated in flowerpots and disposable containers like plastic bottles, to cover water tanks and to collect and dispose properly of waste, he said.

The Brazilian health ministry included similar measures in its campaign for 2013 with the slogan “Dengue é fácil combater, só não pode esquecer” (Dengue is easy to fight, but must not be forgotten), launched at the start of the year.

The aim of the campaign is to reinforce educational messages underlining the need for mass mobilisation for prevention and early treatment of dengue. Every region of the country will undertake specific measures according to the needs of each municipality.

In a bulletin issued Jan. 4, the health ministry reported that in 2012, confirmed dengue cases fell by 64 percent compared with 2011.

Mortality from dengue also declined by 49 percent between these two years. From January to the first week of November 2012, the number of deaths from the disease was 247, while in the same period in 2011 the number was 481.

Estimates from the World Health Organisation indicate that some 2.5 billion people living in tropical and sub-tropical areas are at risk of contracting dengue, and that there are between 60 and 100 million actual cases a year, leading to between 12,000 and 15,000 fatalities annually.

Dengue patients at Cambodia’s National Paediatric hospital. Credit: Erika Pineros/IPS

By Fabiana Frayssinet
RIO DE JANEIRO, Sep 25 2012 (IPS)

Scientists in Brazil announced the start of experiments with an “innocuous, self-sustainable” method to fight transmission of the dengue virus by the Aedes aegypti mosquito, using a bacterium that is naturally occurring in nature.

“We are looking at the possibility of a control method that has a challenging objective: reducing and even eliminating dengue,” Paulo Gadelha, president of the state-run Oswaldo Cruz Foundation (Fiocruz), told the press during a recess in the 18th International Congress on Tropical Medicine and Malaria, running Sunday Sept. 23 to Thursday Sept. 27 in Rio de Janeiro.

Gadelha made the announcement Monday sitting alongside Scott O’Neill, head of the “Eliminate Dengue, Our Challenge” programme led by Monash University of Australia and financed by Fiocruz and the U.S. Foundation for the National Institutes of Health.

The strategy, already approved in Australia, Vietnam and Indonesia, will now be tested in Brazil, as soon as the health and environment agencies give their authorisation.

“This is an important method, because it could become one of the most promising weapons to fight dengue in a natural and sustainable manner, and it poses no risk to the human population or to nature,” Gadelha told IPS after the news briefing.

The technique is based on Wolbachia pipientis, an intracellular bacterium that naturally occurs in more than 70 percent of all insects, such as the fruit fly, butterflies, dragonflies, and several species of mosquito.

But Wolbachia cannot infect affect humans or other vertebrates.

O’Neill and Fiocruz scientist Luciano Moreira explained that after years of research, lab tests showed that when the bacterium is introduced in the Aedes aegypti mosquito, it acts as a vaccine, making the insect resistant to the virus that causes dengue fever – and thus keeping it from spreading the virus to people.

“After thousands of attempts over the space of a number of years, in Australia they managed to infect the eggs of the Aedes aegypti with the bacterium, through microinjections. Afterwards, the bacteria were found in the tissue of the mosquitoes,” Moreira said.

The method is based on the scheduled release of Aedes aegypti mosquitoes infected with Wolbachia which, when they breed with local mosquitoes, pass the bacteria on to the next generation through their eggs.

The idea is for most of the local mosquito population to gradually be infected with Wolbachia, and thus become incapable of spreading dengue, the researchers explained in a Fiocruz statement.

The Aedes aegypti mosquito transmits dengue fever by picking up the virus when it feeds on the blood of an infected person, and infecting other people when it bites them. The symptoms are fever, headache and muscle pain. But haemorrhagic dengue causes intense abdominal pain, nausea and bleeding under the skin and into mucous linings, and can be fatal. There is no vaccine.

Since 2011, the “Eliminate Dengue, Our Challenge” programme has been releasing Wolbachia-infected mosquitoes in different parts of northern Australia, where cases of dengue fever are frequent, although in much smaller numbers than in Brazil and other countries where dengue is endemic.

“Since they transmit Wolbachia from generation to generation through the eggs, and because they have an edge in breeding, with a better chance of leaving young, the mosquitoes carrying the bacteria became predominant in the local populations of Aedes aegypti in just a few weeks,” he added.

The method is considered “self-sustainable” and low-cost, because once the infected mosquitoes begin to be released, “the process does not have to be repeated,” Moreira said.

“The response we have today in Australia is that practically 100 percent of the Aedes aegypti mosquitoes are already producing infected mosquitoes, which indicates that there is a promising chance that the spread of dengue can be stopped,” Gadelha told IPS.

The hope is that Brazil will begin field trials in May 2014 at the latest. Before that, Fiocruz will breed mosquitoes in recipients, “in a contained manner,” to find out if what happened in Australia happens here as well.

It is important for local residents in the areas where the mosquitoes are released to take part in the process, and their participation is secured by getting them to sign a document agreeing to accept the experiment, Moreira said.

In response to questions from the reporters, the scientist clarified that neighbouring countries would also be consulted in case the experiment was expanded to border areas.

The tests will begin in Rio de Janeiro.

IPS asked Gadelha how the scientists could be sure that the mosquitoes inoculated with the Wolbachia bacteria would not cause harm to people in Brazil, given the different climate and biome here.

“The first element of proof is that Wolbachia naturally occurs in 70 percent of insects,” he said. “All of those hundreds of years of (natural) experience show that its spread has no damaging effect on nature or vertebrates, including humans.”

The president of Fiocruz also explained that this is because “Wolbachia only lives inside cells in the mosquitoes. Once the mosquito dies, the bacteria also disappear.”

In addition, “the bacterium is big enough to keep it from reaching the saliva of the mosquitoes, which is how it inoculates animals and human beings,” he said.

“The big advantage shown by the studies is that the presence of the bacteria in the
Aedes aegypti mosquito cuts its lifetime almost by half, while at the same time it keeps the dengue virus from surviving and spreading,” Gadelha said.

The secretary of health monitoring in Brazil’s health ministry, Jarbas Barbosa, said the method would be of “great significance” with respect to fighting a problem like dengue.

There are four subtypes of the virus, which is present in all tropical and many subtropical regions. Epidemics generally break out in the summer months, during or immediately after the rainy season.

According to the World Health Organisation, more than 2.5 billion people – over 40 percent of the world’s population – are now at risk from dengue, the most important viral disease in the world transmitted by mosquitoes.

In the last 50 years, the prevalence of dengue has increased by 30 times, and the WHO reports 50 to 100 million cases a year, in more than 100 countries. Half a million cases require hospitalisation, and about 2.5 percent of hospitalised patients die.

In Latin America and the Caribbean, 554,499 cases were reported in the first half of 2012, according to the Pan American Health Organisation.

The rise in the number of cases was facilitated by humanity itself, with the spread of mosquito breeding grounds, such as garbage dumps and water containers, Barbosa said.

He also said the new method would only be one of the tools used to fight dengue, stressing that the ministry would not stop investing in research along other lines, while continuing to carry out prevention campaigns and to adopt emergency measures when necessary.

The measures taken have managed to bring the incidence of dengue in Brazil down this year, although the number of cases has fluctuated in the last few years, from 632,680 in 2008 to 406,269 in 2009, 1,011,548 in 2010 and 764,032 in 2011.