Summary
Dengue fever
is endemic in over 100 countries and generally non-fatal. According to
the World Health Organization, dengue infects 390 million people every year. So
far this year, the Philippines has reported 146,000 cases and over 600 deaths. Mosquito-borne
illnesses have been on the rise across the East Asia Pacific region, although in most
countries the death toll has stayed beneath 100. Aside from the Philippines, the
highest death rate from dengue this year was in Malaysia, where there have been
76,000 cases and 111 deaths. While most patients recover, severe dengue cases sometimes
result in shock, internal bleeding and possibly death. . The most effective
protective measure is to avoid mosquito bites. This report addresses the
outbreak in the Philippines, and notes what travelers can do to keep themselves
safe.
What is breaking out?
Dengue fever involves
one of four dengue virus strains transmitted by female Aedes mosquito
bites in tropical and subtropical regions. The mosquito is identifiable by
white bands on its legs and silvery scales. Dengue transmission is
possible only via a mosquito biting an infected patient (up to 12 days after
their own infection) and then biting a healthy person approximately eight days
later; it is not transmissible from human to human. Dengue cases in the
Philippines have historically surged in three- to four-year spikes.
Diagnosing
dengue is very difficult, as its symptoms are similar to the flu. Nearly
three-quarters of those infected are asymptomatic. However, classic symptoms
can include lasting and relapsing high fever, headache, pain in the eyes,
muscle/joint/bone pain (dengue was once called “break bone disease”), nausea,
vomiting, rash, minor skin/mucosal hemorrhages, and fatigue. Most patients
recover.
Severe
dengue, which manifests in about 5% of patients, can set in after the fever
begins to subside (defervescence) and lasts about two days. During this time,
blood plasma begins to leak from the capillaries, making the infection far more
serious. Symptoms include intense stomach pain, repeated vomiting possibly with
blood, bleeding from nose/mouth or internally, drowsiness, irritability, and
difficulty breathing. This generally requires protracted hospitalization and
intravenous (IV) fluid replacement.
Where is the
outbreak?
The Western Visayas has recorded
the most cases in the Philippines, with more than 23,000 diagnoses.
Iloilo, Cebu, and Western Mindanao all have a significant number of dengue
cases as well. Many cities are seeking a “state of calamity” to access
emergency funds; seven out of the country’s 17 regions, home to 40% of the
Philippines population, have declared epidemics.
This outbreak is particularly concerning, as there has been a 98% increase of deaths
from dengue compared to this time last year. The most affected group has been
children below the age of ten. Several issues have contributed to this surge in
dengue infections. A vaccine previously used in the Philippines – Dengvaxia – poses
health risks in rare cases, and led to the death of 14 of the 800,000 children
vaccinated between 2016 and 2017. The WHO recommends administering the vaccine only to
those in high-risk areas who have already been exposed to the virus and are
over the age of 9. The Philippines has banned the use of this vaccine, although
another vaccine is not available to replace it, leaving the country with little
means to combat the spread of dengue. The vaccine however, is still available
in the U.S. with significant restrictions.
In addition, the Philippines is in
a tropical zone and receives a significant amount of rain. These continuous
rains can lead to large pools of standing water, where mosquitoes then lay
eggs. Besides the environmental factors that allow mosquitoes to thrive, some
human practices also contribute to the rise in dengue. For example in El Nino,
Palawan, water shortages led people to collect and store water
in containers, which created an increase in standing water where mosquitoes
could breed.
The rainy season in the Philippines
is from June to November.
When temperatures dip, the infection rate begins
to taper. Aedes mosquitoes cannot survive temperatures colder than
10C/50F. However, equatorial countries generally
do not see a sufficient drop in temperature to eliminate the mosquito
population altogether, so dengue remains a threat all year round. In an effort
to counter the spread of mosquitoes, the government has launched “the 4pm habit” initiative, a daily clean-up drive to search out and
destroy potential mosquito breeding grounds.
Why should I be concerned?
Although
many clinical trials are ongoing, there is currently no cure for dengue.
Acetaminophen (also known as
paracetamol outside of the United States) and sponge baths can help with
pain management and fever control, but travelers should avoid aspirin
(including ibuprofen and naproxen) due to its blood-thinning
properties. Travelers should also rest and stay hydrated. Dengue infection does
create a life-long immunity to that particular strain of the virus but not to
the other three strains; a secondary infection with
a different strain raises the risk of severe dengue and shock.
Most
individuals infected with dengue experience roughly a week of acute symptoms
and require about another week for recovery. However, patients with severe
dengue require significantly longer recovery and may experience heightened
fatigue or lethargy for weeks.
Infection
in pregnant women may
result in poor birth outcomes such as stillbirth, low birth weight, and
premature birth.
How do I respond?
Travelers
can protect themselves by preventing mosquito bites. Although there
is no specific treatment for dengue, early detection and access to proper
medical care lowers fatality rates to below 1%. The
CDC offers a dedicated website to reduce the risk of a dengue infection, including preventing
bites. The CDC offers the following recommendations to
avoid mosquito bites:
- Cover exposed skin, including wearing
long sleeves, pants, and hats.
- Use mosquito repellent with high
percentages of active ingredients, like DEET, picaridin, oil of lemon
eucalyptus, or IR3535, and apply it after applying sunscreen.
- Stay in well-screened or air-conditioned
spaces.
- Use a bed net.
- Empty standing water and treat moist
areas with insecticides. Note: studies in India and Brazil
have shown that mosquitoes have developed resistance to some insecticides,
so insecticide rotations and mixtures may delay resistance.
Health professionals should
continue to monitor patients in the days after a fever breaks. Travelers
should seek medical care if they become ill within two weeks of
visiting an infected area.
The
U.S. Embassy in Manila has not issued messaging on dengue fever. Travelers to the
Philippines should remain aware of this disease’s presence and take
countermeasures against infection, especially mosquito bite prevention.
Further information:
For additional information about
the Dengue Fever in the Philippines or other security issues around the region,
contact OSAC’s Asia-Pacific Team and consult the following resources.
