Dengue, the national epidemic, affects the whole world

Print

 

 

By Rose de la Cruz

 

Declared as a national epidemic last July 15 with dengue cases rising to 106,630 from January to June 29 this year, the mosquito-born virus is also afflicting the world, including cold countries that have not been hit by it before.

 

On July 15, Rappler reported that Health Secretary Francisco Duque III noted an 85 percent leap in the number of dengue cases in the first semester this year from just 57,564 cases during the similar period in 2018.

 

A promising antidote to the disease—Dengvaxia vaccine developed by Sanofi—suffered a severe political blow in the last two years causing its removal from the market after panic as a result of reports about (perceived) deaths from its application on public elementary students. With the removal, there was no other way to control the virus from spreading, affecting mostly children.

 

Dengue is the fastest spreading vector-borne disease in the world endemic in 100 countries including the Philippines according to Department of Health. In 2019 alone, the DOH already recorded 17 dengue-related deaths in Bohol as of June 22.

 

The DoH said that the following regions had exceeded the epidemic threshold: Mimaropa, Western Visayas, Central Visayas, and Northern Mindanao.

 

Regions that exceeded the alert threshold are: Ilocos Region, Cagayan Valley, Calabarzon, Bicol, Eastern Visayas, Zamboanga Peninsula, Davao, Bangsamoro Autonomous Region in Muslim Mindanao, and Cordillera Administrative Region.

 

A total of 227 dead and 50,385 dengue cases were reported in Regions CALABARZON, VI, VII, VIII, and XII from 1 January to 13 July 2019.

 

An epidemic threshold is the critical number of cases required for an epidemic to be declared while the alert threshold is the number of cases that sounds an early warning for a potential epidemic.

 

Vigilance

 

Bohol Rep. Alexie Besas Tutor, a physical therapist by training, asked the Department of Education especially the school principals to be vigilant against dengue mosquitoes on campus.

 

 PhilHealth president.CEO BGen Ricardo Morales said it ensures eligible patients with dengue and severe dengue at P10,000 and P16,000, respectively.

 

Tutor said it is common in public schools to have big uncovered drums of water in the comfort rooms and often even the toilet and lavabos itself (with stagnant though clear water) become breeding grounds for the Aedie Aegypti mosquito, which carries the virus.

 

Global incidence

 

The US Center for Disease Control said the infection causes flu-like illness, and occasionally develops into a potentially lethal complication called severe dengue.

 

The global incidence of dengue has grown dramatically in recent decades. About half of the world's population is now at risk. Though dengue is common in tropical and sub-tropical climates, mostly in urban areas, it has been occurring in cold climates that was unheard of in years past.

 

There is no specific treatment for dengue/ severe dengue, but early detection and access to proper medical care lowers fatality rates below 1%.

 

The dengue virus is transmitted by female mosquitoes mainly of the species Aedes aegypti and, to a lesser extent, Ae. albopictus. This mosquito also transmits chikungunya, yellow fever and Zika infection. Dengue is widespread throughout the tropics, with local variations in risk influenced by rainfall, temperature and unplanned rapid urbanization.

 

Severe dengue was first recognized in the 1950s during dengue epidemics in the Philippines and Thailand.

 

Today, severe dengue affects most Asian and Latin American countries and has become a leading cause of hospitalization and death among children and adults in these regions.

 

The incidence of dengue has grown dramatically around the world in recent decades. A vast majority of cases are asymptomatic and hence the actual numbers of dengue cases are under-reported and many cases are misclassified. One estimate indicates 390 million dengue infections per year (95% credible interval 284–528 million), of which 96 million (67–136 million) manifest clinically (with any severity of disease). Another study, of the prevalence of dengue, estimates that 3.9 billion people, in 128 countries, are at risk of infection with dengue viruses, the World Health Organization noted.

 

Member States in three WHO regions regularly report the annual number of cases. The number of cases reported increased from 2.2 million in 2010 to over 3.34 million in 2016. Although the full global burden of the disease is uncertain, the initiation of activities to record all dengue cases partly explains the sharp increase in the number of cases reported in recent years.

 

Before 1970, only 9 countries had experienced severe dengue epidemics. The disease is now endemic in more than 100 countries in the WHO regions of Africa, the Americas, the Eastern Mediterranean, South-East Asia and the Western Pacific. The America, South-East Asia and Western Pacific regions are the most seriously affected.

 

Cases across the Americas, South-East Asia and Western Pacific exceeded 1.2 million in 2008 and over 3.34 million in 2016 (based on official data submitted by Member States). Recently the number of reported cases has continued to increase. In 2015, 2.35 million cases of dengue were reported in the Americas alone, of which 10 200 cases were diagnosed as severe dengue causing 1181 deaths.

 

The year 2016 was characterized by large dengue outbreaks worldwide. The Region of the Americas reported more than 2.38 million cases in 2016, where Brazil alone contributed slightly less than 1.5 million cases, approximately 3 times higher than in 2014. 1032 dengue deaths were also reported in the region. The Western Pacific Region reported more than 375 000 suspected cases of dengue in 2016, of which the Philippines reported 176 411 and Malaysia 100 028 cases, representing a similar burden to the previous year for both countries. The Solomon Islands declared an outbreak with more than 7000 suspected. In the African Region, Burkina Faso reported a localized outbreak of dengue with 1061 probable cases.

 

The Aedes aegypti mosquito is the primary vector of dengue. The virus is transmitted to humans through the bites of infected female mosquitoes. After virus incubation for 4–10 days, an infected mosquito transmits the virus for the rest of its life.

 

The mosquito lives in urban habitats and breeds mostly in man-made containers. Unlike other mosquitoes Ae. aegypti is a day-time feeder; its peak biting periods are early in the morning and in the evening before dusk. Female Ae. aegypti bites multiple people during each feeding period. Aedes eggs can remain dry for over a year in their breeding habitat and hatch when in contact with water.

 

Symptoms

 

Dengue should be suspected when a high fever (40°C/104°F) is accompanied by 2 of the following symptoms: severe headache, pain behind the eyes, muscle and joint pains, nausea, vomiting, swollen glands or rash. Symptoms usually last for 2–7 days, after an incubation period of 4–10 days after the bite from an infected mosquito.

 

Severe dengue is a potentially deadly complication due to plasma leaking, fluid accumulation, respiratory distress, severe bleeding, or organ impairment. Warning signs occur 3–7 days after the first symptoms in conjunction with a decrease in temperature (below 38°C/100°F) and include: severe abdominal pain, persistent vomiting, rapid breathing, bleeding gums, fatigue, restlessness and blood in vomit. The next 24–48 hours of the critical stage can be lethal; proper medical care is needed to avoid complications and risk of death.

 

For severe dengue, medical care by physicians and nurses experienced with the effects and progression of the disease can save lives – decreasing mortality rates from more than 20% to less than 1%. Maintenance of the patient's body fluid volume is critical to severe dengue care.

Immunization

 

Dengvaxia

 

The first dengue vaccine, Dengvaxia® (CYD-TDV) developed by Sanofi Pasteur was licensed in December 2015 and has now been approved by regulatory authorities in 20 countries for use in endemic areas in persons ranging from 9-45 years of age. In April 2016, WHO issued a conditional recommendation on the use of the vaccine for areas in which dengue is highly endemic as defined by seroprevalence of 70% or higher.

 

In November 2017, the results of an additional analysis to retrospectively determine serostatus at the time of vaccination were released. The analysis showed that the subset of trial participants who were inferred to be seronegative at time of first vaccination had a higher risk of more severe dengue and hospitalizations from dengue compared to unvaccinated participants. 

 

WHO’s position

 

The live attenuated dengue vaccine CYD-TDV has been shown in clinical trials to be efficacious and safe in persons who have had a previous dengue virus infection (seropositive individuals), but carries an increased risk of severe dengue in those who experience their first natural dengue infection after vaccination (seronegative individuals). 

 

For countries considering vaccination as part of their dengue control programme, pre-vaccination screening is the recommended strategy. With this strategy, only persons with evidence of a past dengue infection would be vaccinated (based on an antibody test, or on a documented laboratory confirmed dengue infection in the past). 

 

Vaccination should be considered as part of an integrated dengue prevention and control strategy. There is an ongoing need to adhere to other disease preventive measures such as well-executed and sustained vector control. Individuals, whether vaccinated or not, should seek prompt medical care if dengue-like symptoms occur.

 

Control and Prevention

 

At present, the main methods of controlling and preventing the spread of dengue virus is to combat vector mosquitoes are: preventing mosquitoes from accessing egg-laying habitats by environmental management and modification; disposing of solid waste properly and removing artificial man-made habitats; covering, emptying and cleaning of domestic water storage containers on a weekly basis; applying appropriate insecticides to water storage outdoor containers; using of personal household protection measures, such as window screens, long-sleeved clothes, repellents, insecticide treated materials, coils and vaporizers (These measures have to be observed during the day both at home and place of work since the mosquito bites during the day); improving community participation and mobilization for sustained vector control; applying insecticides as space spraying during outbreaks as one of the emergency vector-control measures and active monitoring and surveillance of vectors should be carried out to determine effectiveness of control interventions.

 

Careful clinical detection and management of dengue patients can significantly reduce mortality rates from severe dengue, the WHO said.

 

Palace open to Dengvaxia

 

With 456 deaths from dengue this year, Malacanang said it is open to reviving the dengue vaccination if experts attest it is safe to use.


At 456 deaths from dengue this ratio is still considered low at 0.4 percent. But the health department’s goal is to reduce the numbers down to less than 0.2 percent.

 

 

To fight dengue, the DoH outlined 45 strategies, among them:  Search and destroy mosquito breeding places; self-protective measures like wearing long sleeves and use of insect repellent; seek early consultation on the first signs and symptoms of the disease; say yes to fogging if there is an impending outbreak.