Global & Disaster Medicine

Archive for the ‘Dengue’ Category

New research shows that the geographical range of vector-borne diseases such as chikungunya, dengue fever, leishmaniasis, and tick-borne encephalitis (TBE) is expanding rapidly.


“……..Global warming has allowed mosquitoes, ticks and other disease-carrying insects to proliferate, adapt to different seasons, and invade new territories across Europe over the past decade–with accompanying outbreaks of dengue in France and Croatia, malaria in Greece, West Nile Fever in Southeast Europe, and chikungunya virus in Italy and France. …….”

Dengue fever – Jamaica: 339 suspected and confirmed cases, including 6 deaths, reported from Jan 1 through Jan 21


Dengue fever – Jamaica

Disease outbreak news
4 February 2019

On 3 January 2019, the International Health Regulations (IHR) National Focal Point of Jamaica notified WHO of an increase in dengue cases in Jamaica.

From 1 January though 21 January 2019, 339 suspected and confirmed cases including six deaths were reported (Figure 1). In 2018, a total of 986 suspected and confirmed cases of dengue including 13 deaths have been reported. The number of reported dengue cases in 2018 was 4.5 times higher than that reported in 2017 (215 cases including six deaths). Cases reported to date for 2019 exceed the epidemic threshold (Figure 2).

According to historic data, Jamaica reported a major outbreak in 2016, when 2297 cases of dengue infection including two deaths were reported. Dengue virus 3 (DENV3) and DENV4 circulations were confirmed at the time.

By the end of 2018, the largest number of reported cases were notified by Kingston and Saint Andrew parishes. In 2019 so far, the largest proportion of cases have been reported by Saint Catherine parish.

Laboratory tests have identified DENV3 as the dengue serotype currently circulating.

In January 2019, some countries and territories in the Caribbean region, such as Guadeloupe, Martinique, and Saint Martin, reported an increase in dengue cases. Of note, in Saint Martin and Guadeloupe, serotype DENV1 is currently circulating.

Figure 1. Dengue fever cases and deaths by week of onset from 1 January 2018 through 21 January 2019 in Jamaica*

Public health response

  • The Ministry of Health (MoH) declared the dengue outbreak on 3 January 2019.
  • Health authorities in Jamaica are implementing measures for the following activities; strengthened integrated vector control, enhanced surveillance of cases, social mobilization, clinical management, enhanced laboratory diagnostic capacity, and emergency risk communications.
  • The MoH has been collaborating with the Pan American Health Organization (PAHO/WHO) and other international agencies to strengthen and co-ordinate the response activities.
  • Since July 2018, the MoH has intensified its vector control activities.
  • The MoH launched the Emergency Operations Centre on 27 December 2018; and fully activated it on 3 January 2019 to facilitate the coordination and reporting of activities. The response activities are geared towards strengthening the response capacity with adequate human resources, as well as supporting efforts to reduce the entomological indices for the Aedes aegypti mosquito across the island and enhancing clinical management capacity.

WHO risk assessment

Jamaica has been reporting dengue cases since 1990 and throughout 2018; however, an increase has been observed since December 2018 exceeding the epidemic threshold. Similar large increases were reported in 2010 (2887 cases), 2012 (4670 cases), and 2016 (2297 cases). The increase of dengue in the Caribbean islands may result in more severe secondary dengue virus infections and require comprehensive risk communication.

WHO advice

On 21 November 2018, PAHO/WHO alerted Member States about an increase in dengue cases in countries and territories in the Americas and recommended coordinated actions both inside and outside of the health sector, including prioritizing activities to prevent transmission of dengue as well as deaths due to this disease.

PAHO/WHO further advises to follow the key recommendations regarding outbreak preparedness and response, case management, laboratory, and integrated vector management as published in the 21 November 2018 PAHO/WHO Epidemiological Update on Dengue, available at the link below.

There is no specific treatment for disease due to dengue; therefore, prevention is the most important step to reduce the risk of dengue infection. WHO recommends proper and timely case management of dengue cases. Surveillance should continue to be strengthened within all affected areas and at the national level. Key public health communication messages should continue to be provided to reduce the risk of transmission of dengue in the population.

In addition, integrated vector management (IVM) activities should be enhanced to remove potential breeding sites, reduce vector populations, and minimize individual exposures. This should include both larval and adult vector control strategies (i.e. environmental management and source reduction, and chemical control measures), as well as strategies to protect individuals and households. Where indoor biting occurs, household insecticide aerosol products, mosquito coils, or other insecticide vaporizers may also reduce biting activity. Household fixtures such as window and door screens and air conditioning can also reduce biting. Since Aedes mosquitoes (the primary vector for transmission) are day-biting mosquitoes, personal protective measures such as use of clothing that minimizes skin exposure during daylight hours is recommended. Repellents may be applied to exposed skin or to clothing. The use of repellents must be in strict accordance with label instructions. Insecticide-treated mosquito nets afford good protection for those who sleep during the day (e.g. infants, the bedridden, and night-shift workers) as well as during the night to prevent mosquito bites.

WHO does not recommend any general travel or trade restrictions be applied based on the information available for this event.

Pakistan: Report on Dengue and Crimean-Congo Fever


“…..From 2015 till today, 51,764 people infected with dengue in the country of whom 107 people have died…….

The Congo virus on the other hand, has infected 613 people in the same time period. Of these people, 148 died due to the disease….”

Distribution Map for Crimean-Cogngo Hemorrhagic Fever. Areas endecmic of CCHF are Azerbaijan, Benin, Bosnia and Herzegovina, Bulgaria, Burkina Faso, Central African Republic, Congo DRC, Croatia,Egypt, Ethiopia, Georgia, Greece, Guinea, Gujart India, Iran, Iraq, Kazakhstan, Kenya, Kyrgyzstan, Madagascar, Mauritania, Montenegro, Namibia, Nigeria, Oman, Pakistan, Rajasthan India, Russia, Saudi Arabia, Senegal, Serbia, Slovenia, South Africa, South Sudan, Sudan, Tajikistan, Tanzania, Macedonia, Turkey, Turkmenistan, Uganda, Ukraine, United Arab Emirates, Uzbekistan, Xinjiang China, and Zimbabwe

Map 3-01. Distribution of dengue in the Americas and the Caribbean

Map 3-02. Dengue risk in Africa and the Middle East

Map 3-03. Dengue risk in Asia and Oceania

Thailand: Dengue cases top 70,000 in 1st 10 months of 2018

Outbreak News

Global Map of Dengue Fever

Aedes albopictus, a vector for Zika, Dengue, and Yellow Fever, has been spotted in Eindhoven, Netherlands

The Dutch News


The mosquito, Aedes albopictus, that is responsible for transmitting Zika virus and yellow fever is closing in on Portugal

The Portugal News


Dengue in pregnancy may increase risk of congenital brain malformations


“….Researchers found that confirmed dengue during pregnancy increased the odds of a neurologic congenital anomaly by 50%, but the results were not statistically significant (95% confidence interval, 0.97-2.27). Congenital malformation of the spinal cord, however, and some congenital brain malformations were more than four times more frequent in dengue-affected births….”

Paixão ES, Teixeira MG, da Conceição N. Costa M, Barreto ML, Rodrigues LC. Enny S. Paixão. Symptomatic dengue during pregnancy and congenital neurologic malformations. Emerg Infect Dis. 2018 Sep [date cited].

Sterile Insect Technique on Aedes aegypti mosquitoes


In an international partnership between CSIRO, Verily and James Cook University, scientists used specialised technology to release millions of sterilised male Aedes aegypti mosquitoes across the Cassowary Coast in Queensland in a bid to combat the global pest.

CSIRO Director of Health and Biosecurity Dr Rob Grenfell said the results were a major win in the fight against diseases-spreading mosquitoes.

“The invasive Aedes aegypti mosquito is one of the world’s most dangerous pests, capable of spreading devastating diseases like dengue, Zika and chikungunya and responsible for infecting millions of people with disease around the world each year,” Dr Grenfell said.

“Increased urbanisation and warming temperatures mean that more people are at risk, as these mosquitoes which were once relegated to areas near the equator forge past previous climatic boundaries.

“Although the majority of mosquitoes don’t spread diseases, the three mostly deadly types the Aedes, Anopheles and Culex are found almost all over the world and are responsible for around 17 per cent of infectious disease transmissions globally.”

From November 2017 to June this year, non-biting male Aedes aegypti mosquitoes sterilised with the natural bacteria Wolbachia were released in trial zones along the Cassowary Coast in North Queensland.

They mated with local female mosquitoes, resulting in eggs that did not hatch and a significant reduction of their population.

“Our heartfelt thanks goes out to the Innisfail community who literally opened their doors to our team, letting us install mosquito traps around their homes and businesses – we couldn’t have done this without your support,” Dr Grenfell said.

The process, known as the Sterile Insect Technique, has been successfully used since the 1950s but the challenge in making it work for mosquitoes like the Aedes aegypti has been rearing enough mosquitoes, removing biting females, identifying the males and then releasing the huge numbers needed to suppress a population.

To address this challenge, Verily, an affiliate of Alphabet Inc, developed a mosquito rearing and sex sorting and release technology as part of its global Debug project.

“We’re very pleased to see strong suppression of these dangerous biting female Aedes aegypti mosquitoes,” Verily’s Nigel Snoad said.

“We are particularly thankful to the people of Innisfail for their strong support, which has been incredible.

“We came to Innisfail with CSIRO and JCU to see how this approach worked in a tropical environment where these mosquitoes thrive, and to learn what it was like to operate our technology with research collaborators as we work together to find new ways to tackle these dangerous mosquitoes.”

Scientists compared the number of Aedes aegypti mosquitoes trapped in release sites and control zones to monitor and track populations.

The millions of mosquitoes needed for the trial were reared at James Cook University in Cairns.

To produce the three million male mosquitoes needed for the trial, researchers at James Cook University (JCU) in Cairns set out to raise almost 20 million Aedes aegypti.

“We allowed for the possibility of deaths during the process, as well as the need to sift out the female half of the population,” Dr Kyran Staunton from James Cook University said.

“Verily’s technology enabled us to do the sex sorting faster and with much higher accuracy.

“We learnt a lot from collaborating on this first tropical trial and we’re excited to see how this approach might be applied in other regions where Aedes aegypti poses a threat to life and health.”

“The health of our nation is paramount as we help Australia achieve its vision to become one of the healthiest nations on earth,” CSIRO Chief Executive Dr Larry Marshall said.

“By enabling industry partners like Verily to leverage the world-leading health capability we have built in CSIRO we can deliver this moonshot and tackle some of the world’s most wicked challenges with science.”

Clinical differences between Dengue and Zika


Yan G, Pang L, Cook AR, Ho HJ, Win MS, Khoo AL, et al. Distinguishing Zika and dengue viruses through simple clinical assessment, Singapore. Emerg Infect Dis. 2018 Aug [date cited].

“…Conjunctivitis strongly indicated Zika virus infection (odds ratio [OR] 30.1, 95% CI 9.57–94.44; p < 0.001). In contrast, fever (OR 0.05, 95% CI 0.01–0.47; p = 0.008), myalgia (OR 0.20, 95% CI 0.08–0.48; p<0.001), and headache (OR 0.12, 95% CI 0.05–0.30; p<0.001) were more prominent in patients with DENV infection.

Further, DENV patients tended to have thrombocytopenia (median platelet count 132 × 109/µL, range 15–386 × 109/µL) and monocytosis (median monocyte count 0.50 × 109/µL, range 0.11–1.70 × 109/µL), whereas Zika patients tended to have normal platelet (median 225 × 109/µL, range 128–326 × 109/µL; p<0.001) and monocyte (median 0.35 × 109/µL, range 0.13–1.00 × 109/µL; p = 0.021) counts……”

Climate change and dengue fever in Latin America

Felipe J. Colón-González el al., “Limiting global-mean temperature increase to 1.5–2 °C could reduce the incidence and spatial spread of dengue fever in Latin America,” PNAS (2018).

Read more at:

“……We show that policies to limit global warming to 2 °C could reduce dengue cases by about 2.8 (0.8–7.4) million cases per year by the end of the century compared with a no-policy scenario that warms by 3.7 °C. Limiting warming further to 1.5 °C produces an additional drop in cases of about 0.5 (0.2–1.1) million per year…..”

Land Surface Temperature




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