Global & Disaster Medicine

Archive for the ‘Dengue’ Category

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



Since January, Reunion has recorded 1,816 cases of Dengue Fever


On 16 March 2018, WHO was notified by the International Health Regulations (2005) National Focal Point for France through the European Commission (EC) Early Warning and Response System (EWRS) about a sharp increase in the number of dengue cases reported in Réunion, France since the beginning of 2018. Réunion is a French overseas territory in the Indian Ocean.

Piton de la Fournaise NOAA:  “Considered one of the world’s most active volcanoes, Piton de la Fournaise occupies the east-southeastern end of Réunion Island in the western Indian Ocean.


As of 23 April, 1816 autochthonous dengue cases have been confirmed in Réunion in 2018, including 428 probable and confirmed cases reported from 16-23 April 2018; in comparison, less than 100 cases were reported in all of 2017. The western and southern parts of the island are the most affected. The number of emergency room visits and hospitalizations related to dengue fever have been increasing; 50 hospitalizations in 2018 have been reported compared to 12 hospitalizations for all of 2017. At this stage of the outbreak, the hospitals have the capacities to provide clinical care for all of the reported cases. Since the beginning of 2017, the main circulating strain is DENV-2 (537 serotypings); other serotypes have also been detected mainly among imported cases in 2017 (four DENV-1 and one DENV-4 serotypings). In 2014, DENV-2 was the main circulating serotype in 2014, along with DENV-1 and DENV-3; in 2016, DENV-1, was the main serotype along with DENV-2 and DENV-3.

Aedes albopictus and Aedes aegypti mosquitos are both found in Réunion; however, Ae. albopictus has historically had the highest observed abundance.

Public health response

Since 2006, notification of dengue infection to public authorities in Réunion is compulsory. Indian Ocean Regional Office of the French Institute for Public Health (Cire OI – Santé Publique France), in collaboration with the vector control team (Lutte anti-vectorielle, LAV) of the French Health Agency Indian Ocean (ARS-OI), is closely monitoring this outbreak. The following actions have been implemented in Réunion by public authorities:

  • Reinforced vector control measures, focusing primarily in areas around reported dengue cases;
  • Enhanced surveillance of cases;
  • Blood and safety of substances of human origin (SoHo) safety measures implemented;
  • Social mobilization activities; and
  • Specific risk communication messages aiming to raise dengue fever awareness among the public and health care workers, including posters at points of entry (PoE) and announcements onboard flights to and from Réunion.

On 27 March 2018, public authorities raised the level of the emergency plan “Organisation de la Réponse de Sécurité Civile” (ORSEC) to 3, corresponding to a low-level epidemic. This plan includes:

  • Active case finding;
  • Intensified vector control;
  • Reinforced communication to the public and health care workers;
  • Mobilization of additional resources, including human resources (e.g., firefighters).

WHO risk assessment

Although sporadic autochthonous dengue fever cases and clusters have been reported in Réunion before, the upsurge of cases since the beginning of 2018 is unprecedented. This could be partly explained by:

  • According to studies, in previous years asymptomatic cases contributed to the transmission cycle and since the proportion of asymptomatic cases was high, the virus has continued to spread unnoticed until now; and
  • A lack of herd immunity in the local population, as only sporadic cases have been reported on the island before, thus favouring further transmission of the virus.

Réunion is a popular tourist destination and the likelihood of dengue virus introduction to other countries is heightened by the current outbreak.

The presence of competent mosquito vectors and the uncertainty regarding the level of dengue immunity of the local population highlight the need for enhanced risk communication and entomological and epidemiological surveillance to rapidly and effectively control the epidemic.

WHO advice

  • WHO recommends enhancing Integrated Vector Management (IVM) activities to remove potential breeding sites, reduce vector populations and minimize individual exposures. This should include both vector control strategies (i.e. environmental management, and chemical and biological control measures), as well as strategies to protect individuals and households. For further information, see references below.
  • Since the Aedes mosquitoes, are day-biting mosquitoes, personal protective measures such as the use of clothing that minimizes skin exposure during daylight hours is recommended. Repellents that contain DEET (diethyltoluamide), IR 3535 ((3- [N-butyl-N-acetyl], aminopropionic acid ethyl-ester) or KBR3023 (also called “Icaridin” or “Picaridin”) 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), but also during the night to prevent mosquito bites, if the lights are kept on.
  • Where indoor biting occurs, household insecticide aerosol products, mosquito coils or other insecticide vaporizers may also reduce biting activity. Household fixtures such as windows, door screens and air-conditioning can also reduce biting.
  • There is no specific treatment for dengue fever. Careful clinical detection and management of dengue patients can significantly reduce mortality rates from severe dengue.
  • WHO advises against any restrictions on travel to or trade with Réunion based on the information available.


U.S. trends in occurrence of nationally reportable vectorborne diseases during 2004–2016.


Rosenberg R, Lindsey NP, Fischer M, et al. Vital Signs: Trends in Reported Vectorborne Disease Cases — United States and Territories, 2004–2016. MMWR Morb Mortal Wkly Rep. ePub: 1 May 2018. DOI:

Key Points

•A total of 642,602 cases of 16 diseases caused by bacteria, viruses, or parasites transmitted through the bites of mosquitoes, ticks, or fleas were reported to CDC during 2004–2016. Indications are that cases were substantially underreported.

•Tickborne diseases more than doubled in 13 years and were 77% of all vectorborne disease reports. Lyme disease accounted for 82% of all tickborne cases, but spotted fever rickettsioses, babesiosis, and anaplasmosis/ehrlichiosis cases also increased.

•Tickborne disease cases predominated in the eastern continental United States and areas along the Pacific coast. Mosquitoborne dengue, chikungunya, and Zika viruses were almost exclusively transmitted in Puerto Rico, American Samoa, and the U.S. Virgin Islands, where they were periodically epidemic. West Nile virus, also occasionally epidemic, was widely distributed in the continental United States, where it is the major mosquitoborne disease.

•During 2004–2016, nine vectorborne human diseases were reported for the first time from the United States and U.S. territories. The discovery or introduction of novel vectorborne agents will be a continuing threat.

•Vectorborne diseases have been difficult to prevent and control. A Food and Drug Administration–-approved vaccine is available only for yellow fever virus. Many of the vectorborne diseases, including Lyme disease and West Nile virus, have animal reservoirs. Insecticide resistance is widespread and increasing.

•Preventing and responding to vectorborne disease outbreaks are high priorities for CDC and will require additional capacity at state and local levels for tracking, diagnosing, and reporting cases; controlling vectors; and preventing transmission.

The figure above is a map of the United States showing reported cases of tickborne disease in U.S. states and territories during 2004–2016.

Reported cases* of tickborne disease — U.S. states and territories, 2004–2016


The figure above is a map of the United States showing reported cases of mosquitoborne disease in U.S. states and territories during 2004–2016.

Reported cases* of mosquitoborne disease — U.S. states and territories, 2004–2016


The figure above is a bar chart showing reported nationally notifiable mosquitoborne, tickborne, and fleaborne disease cases in U.S. states and territories during 2004–2016.

Reported nationally notifiable mosquitoborne,* tickborne, and fleaborne disease cases — U.S. states and territories, 2004–2016

ADE (antibody dependent enhancement): The dengue phenomenon wherein antibodies from a previous dengue infection counterintuitively worsen subsequent infections with the flavivirus.


WHO advises Dengvaxia be used only in people previously infected with dengue

Following a consultation of the Global Advisory Committee on Vaccine Safety, the World Health Organization (WHO) finds that the dengue vaccine CYD-TDV, sold under the brand name Dengvaxia, prevents disease in the majority of vaccine recipients but it should not be administered to people who have not previously been infected with dengue virus.

This recommendation is based on new evidence communicated by the vaccine’s manufacturer (Sanofi Pasteur), indicating an increase in incidence of hospitalization and severe illness in vaccinated children never infected with dengue.

The WHO Global Advisory Committee on Vaccine Safety considered the company’s new results from clinical trial data analyses. Those studies indicate that increased risk of severe dengue disease in people who have never been infected affects about 15% of the vaccinated individuals. The magnitude of risk is in the order of about 4 out of every 1000 seronegative patients vaccinated who developed severe dengue disease during five years of observation. The risk of developing severe dengue disease in non-vaccinated individuals has been calculated as 1.7 per 1000 over the same period of observation. By contrast, for the 85% who have had dengue disease before immunization, there is a reduction of 4 cases of severe dengue per 1 000 who are vaccinated.

The possibility of risk for seronegative people was raised by WHO and published in a position paper in July 2016: “…vaccination may be ineffective or may theoretically even increase the future risk of hospitalized or severe dengue illness in those who are seronegative at the time of first vaccination regardless of age.”[i] As this risk had at that time not been seen in the age groups for which the vaccine was licensed, WHO issued a conditional recommendation, emphasizing the use of the vaccine in populations having been previously infected with dengue virus.

To minimize illness for seronegative vaccinated people, WHO recommends enhancing measures that reduce exposure to dengue infection among populations where the vaccine has already been administered. For vaccine recipients who present with clinical symptoms compatible with dengue virus infection, access to medical care should be expedited to allow for proper evaluation, identification, and management of severe forms of the disease.


Dengue is a mosquito-borne flavivirus disease that has spread to most tropical and many subtropical areas. The disease is caused by four closely related viruses. There is no specific dengue treatment and prevention is mainly limited to vector control measures. A safe and effective dengue vaccine would therefore represent a major advance in the control of the disease.

CYD-TDV is a live attenuated tetravalent vaccine made using recombinant DNA technology and is administered in three phases separated by six-month intervals. It became commercially available in 2016 and is currently licensed in 19 countries.

[i] Dengue vaccine: WHO position paper – July 2016

Dengue fever – Burkina Faso


Dengue fever – Burkina Faso

Disease outbreak news
6 November 2017

Burkina Faso has been experiencing an epidemic of dengue fever since week 31 of 2017 (week ending on 6 August). WHO officially declared the outbreak on 28 September 2017. Unlike the previous occurrence in 2016, several serotypes of dengue have been detected and the number of cases quickly exceeded past seasonal outbreaks.

As of 27 October 2017, a total of 6 699 (suspected, probable or confirmed) cases and 13 deaths (CFR= 0.2%) were reported throughout the country. Of the total cases reported, 4 428 (66%) were probable, with a positive result for dengue by rapid diagnostic test (RDT), of 241 samples referred for PCR testing at the Viral Haemorrhagic fever (VHF) reference lab of the Centre Muraz, Bobo-Dioulasso, 141 (59%) were confirmed cases by positive result. Further characterization of 72 samples has identified three dengue virus serotypes: DENV-2 (N=58), DENV-3 (N=12) and DENV-1 (N=2). Cases are currently reported in 12 of the country’s 13 health regions, with 64% of cases reported in the central region, particularly in the city of Ouagadougou.

Public health response

  • The National Epidemic Management Committee has been activated to coordinate response activities.
  • Strengthening the epidemiological surveillance, and putting in place an Early Warning System that provides daily notification of cases in Ouagadougou and weekly in the other provinces.
  • Provision of free medical care and treatment for severe cases in all hospitals (Regional and District hospitals). 5 000 RDTs distributed to reference health centers.
  • Development and dissemination of a national dengue clinical management algorithm.
  • Delivery and dissemination of key awareness and prevention measures through radio and television programs.
  • Periodic shipment of samples to the VHF laboratory of the Centre Muraz, Bobo-Dioulasso.
  • Implementation of intensive vector control interventions targeting larva and adult mosquitoes through.
    • Elimination of mosquito breeding sites which was carried out by community volunteers in Ouagadougou;
    • Distribution of 1 500 Long Lasting Insecticidal Nets (LLINs) to hospitals;
    • Ongoing in-door spraying to control adult mosquitoes at the household level.

WHO risk assessment

This outbreak is occurring in the context of an improved but still limited dengue surveillance system in Burkina Faso. The weekly case incidence has been on the rise since the detection of the outbreak in week 31 and is likely underestimated. The epidemic has already spread to twelve of the country’s thirteen health zones and many public health facilities do not have access to dengue fever diagnostics (RDTs).

Burkina Faso experienced an outbreak of dengue in 2016 which was caused by DENV-2. In the current outbreak, three serotypes were identified: DENV-1, DENV-2, and DENV-3. This could lead to the occurrence of more severe cases, which may not be captured by the surveillance system due to under-reporting from private clinics and healthcare centers in peripheral districts.

The existence of multiple mosquito breeding sites after the rainy season may favor the continued presence of mosquito populations in the affected communities In particular, the peripheral districts of cities in Burkina Faso are characterized by poor sanitation and the accumulation of rubbish dump sites, tires and used containers which provide productive breeding sites for Aedes aegypti mosquitoes (the primary vector for dengue).

WHO advice

WHO recommends adequate and timely case management dengue cases. Surveillance should be strengthened within all affected health zones. Key public health communication messages should be provided. Integrated Vector Management (IVM) activities should be enhanced to remove potential breeding sites, reduce vector populations and minimize individual exposures. This should include both vector control strategies (i.e. environmental management, and chemical and biological control measures), as well as strategies to protect individuals and households. For further information, see:

WHO recommends that countries should consider the introduction of the dengue vaccine CYD-TDV only in geographic settings (national or subnational) where epidemiological data indicate a high burden of disease. Complete recommendations may be found in the WHO position paper on dengue vaccines:

WHO advises against any restriction on travel and trade to Burkina Faso or the affected district based on the available information.

CDC recommendations to healthcare providers treating patients in Puerto Rico and USVI, as well as those treating patients in the continental US who recently traveled in hurricane-affected areas during the period of September 2017 – March 2018.


Advice for Providers Treating Patients in or Recently Returned from Hurricane-Affected Areas, Including Puerto Rico and US Virgin Islands

Distributed via the CDC Health Alert Network
October 24, 2017, 1330 ET (1:30 PM ET)

The Centers for Disease Control and Prevention (CDC) is working with federal, state, territorial, and local agencies and global health partners in response to recent hurricanes. CDC is aware of media reports and anecdotal accounts of various infectious diseases in hurricane-affected areas, including Puerto Rico and the US Virgin Islands (USVI). Because of compromised drinking water and decreased access to safe water, food, and shelter, the conditions for outbreaks of infectious diseases exist.

The purpose of this HAN advisory is to remind clinicians assessing patients currently in or recently returned from hurricane-affected areas to be vigilant in looking for certain infectious diseases, including leptospirosis, dengue, hepatitis A, typhoid fever, vibriosis, and influenza. Additionally, this Advisory provides guidance to state and territorial health departments on enhanced disease reporting.


Hurricanes Irma and Maria made landfall in Puerto Rico and USVI in September 2017, causing widespread flooding and devastation. Natural hazards associated with the storms continue to affect many areas. Infectious disease outbreaks of diarrheal and respiratory illnesses can occur when access to safe water and sewage systems are disrupted and personal hygiene is difficult to maintain. Additionally, vector borne diseases can occur due to increased mosquito breeding in standing water; both Puerto Rico and USVI are at risk for outbreaks of dengue, Zika, and chikungunya.

Health care providers and public health practitioners should be aware that post-hurricane environmental conditions may pose an increased risk for the spread of infectious diseases among patients in or recently returned from hurricane-affected areas; including leptospirosis, dengue, hepatitis A, typhoid fever, vibriosis, and influenza. The period of heightened risk may last through March 2018, based on current predictions of full restoration of power and safe water systems in Puerto Rico and USVI.

In addition, providers in health care facilities that have experienced water damage or contaminated water systems should be aware of the potential for increased risk of infections in those facilities due to invasive fungi, nontuberculous Mycobacterium species, Legionella species, and other Gram-negative bacteria associated with water (e.g., Pseudomonas), especially among critically ill or immunocompromised patients.

Cholera has not occurred in Puerto Rico or USVI in many decades and is not expected to occur post-hurricane.



These recommendations apply to healthcare providers treating patients in Puerto Rico and USVI, as well as those treating patients in the continental US who recently traveled in hurricane-affected areas (e.g., within the past 4 weeks), during the period of September 2017 – March 2018.

  • Health care providers and public health practitioners in hurricane-affected areas should look for community and healthcare-associated infectious diseases.
  • Health care providers in the continental US are encouraged to ask patients about recent travel (e.g., within the past 4 weeks) to hurricane-affected areas.
  • All healthcare providers should consider less common infectious disease etiologies in patients presenting with evidence of acute respiratory illness, gastroenteritis, renal or hepatic failure, wound infection, or other febrile illness. Some particularly important infectious diseases to consider include leptospirosis, dengue, hepatitis A, typhoid fever, vibriosis, and influenza.
  • In the context of limited laboratory resources in hurricane-affected areas, health care providers should contact their territorial or state health department if they need assistance with ordering specific diagnostic tests.
  • For certain conditions, such as leptospirosis, empiric therapy should be considered pending results of diagnostic tests— treatment for leptospirosis is most effective when initiated early in the disease process. Providers can contact their territorial or state health department or CDC for consultation.
  • Local health care providers are strongly encouraged to report patients for whom there is a high level of suspicion for leptospirosis, dengue, hepatitis A, typhoid, and vibriosis to their local health authorities, while awaiting laboratory confirmation.
  • Confirmed cases of leptospirosis, dengue, hepatitis A, typhoid fever, and vibriosis should be immediately reported to the territorial or state health department to facilitate public health investigation and, as appropriate, mitigate the risk of local transmission. While some of these conditions are not listed as reportable conditions in all states, they are conditions of public health importance and should be reported.


For More Information

Dengue: New Dengue Case Definitions (2009)


Dengue without Warning Signs expanded

Fever and two of the following:

Nausea, vomiting


Aches and pains


Positive tourniquet test


Dengue with Warning Signs** collapsed

Dengue as defined above with any of the following:

Abdominal pain or tenderness

Persistent vomiting

Clinical fluid accumulation (ascites, pleural effusion)

Mucosal bleeding

Lethargy, restlessness

Liver enlargement >2 cm

Laboratory: increase in HCT concurrent with rapid decrease in platelet count

**requires strict observation and medical intervention


Severe Dengue collapsed

Dengue with at least one of the following criteria:
Severe Plasma Leakage leading to:

– Shock (DSS)
– Fluid accumulation with respiratory distress

Severe Bleeding as evaluated by clinician

Severe organ involvement

– Liver: AST or ALT ≥ 1000

– CNS: impaired consciousness

– Failure of heart and other organs




CDC: Dengue Management Guide (Clinical management tools for health care providers)

CDC-Dengue Management Guide


Life cycle of mosquitos in a diagram

Life cycle of mosquitos in jars



Surge of Dengue cases in Myanmar (Burma): More than 4500 cases


Date: Thu 31 Aug 2017 10:31
Source: Eleven Media [in Myanmar, trans. Mod.YMA, edited]

“The dengue cases reported in Yangon Region during 2017 are higher than
those of 2016. During the 1st 4 months, the incidence increased as
high as 4 times [than that of 2016].

At present, there are more than 4500 cases and 32 deaths of dengue
infection. Larvae control activities are being carried out in the
areas with high incidence. The highest number of cases are found in
Hlaingtharya, 4 areas in Dagon Myothit, Dala, Thaketa, Mayangone, and
Hlaing Townships as usual, according to the Regional Public Health
Department in Yangon Region.”

[Byline: Ei Thinzar Kyaw]

Global Map of Dengue Fever Source:  CDC


An adult Aedes aegypti mosquito, the species responsible for the majority of human Zika virus cases, has been found in Canada for the first time.



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