About 40% of the world’s populations live in regions with a high risk for dengue infection. The World Health Organization (WHO) estimates that between 50-100 million infections occur annually. About 500,000 progress to dengue hemorrhagic fever, resulting to 22,000 deaths.
Dengue is a perennial health issue in the Philippines, being one of the 100 countries at high risk for outbreaks. Seasonal outbreaks happen during the wet season, between the months of June to February. The first known dengue epidemic in the country occurred in Manila from 1953-1954. World War II, which was consummated a decade before, created ideal conditions for mosquito-borne diseases. By the 1970’s, dengue has spread throughout Southeast Asia.
According to the country’s Department of Health (DOH), the 5-year average for dengue is at 185,008 infections. The 5-year average number of deaths stands at 732. The young disproportionately bears the majority of infections, with around 80% of cases in the country hitting those aged between 5 and 14.
In 2016, the Department of Health (DOH) launched a massive immunization campaign against dengue, becoming one of the first Asian countries to approve the sale and distribution of Dengvaxia—a vaccine produced by the French pharmaceutical Sanofi Pasteur. However, in late November 2017, after Sanofi admitted that the product posed serious threats to persons without prior exposure to dengue, DOH suspended the school-based initiative. A number of fatal complications, supposedly linked to the vaccine, have cropped up. The Philippine government and concerned agencies are currently critically investigating the matter. By December 2018, the Public Attorney’s Office (PAO) have filed the Department of Justice (DOJ) the 30th Dengvaxia-related complaint against DOH officials who spearheaded the 2016 campaign.
What is Dengue?
Aedes aegypti mosquito
Dengue is a mosquito-borne virus endemic in tropical and subtropical countries like the Philippines. The virus presents flu-like symptoms, which can often be mistaken for high fever. However, when left untreated, severe dengue cases can be fatal.
Dengue is spread most commonly by the female Aedes aegypti mosquito—usually a day-biting mosquito.
It acquires the dengue virus by feeding on the blood of an already infected person. (According to the Centers for Diseases Control, monkeys were the original hosts of the virus between 100 and 800 years ago.)
When an infected mosquito bites on a person, it transmits the virus through its saliva, delivering it into the bloodstream. Once there, the virus rapidly replicates and flu-like symptoms appear in 4-7 days.
There are 5 known strains of the virus: DENV-1, DENV-2, DENV-3, DENV-4, DENV-5. These are related to the West Nile virus and Yellow fever virus. Exposure and recovery from one of the dengue strains leads to a lifelong immunity to that particular serotype. However, later exposure to a different strain can actually cause more severe risks and complications. For example, a patient previously exposed to DENV-1 is said to be immuned from further DENV-1 infections, but remains susceptible to the 4 other known strains.
For the last 50 years, it was thought that the dengue virus only has 4 different strains. But in October 2013, a 5th serotype was announced by a team of scientists from the University of Texas Medical Branch (UTMB). The strain is said to be hosted by macaque monkeys in the jungles of Malaysia and Indonesia, and so far has not yet been involved in any sustained dengue outbreaks. Scientists believe that more dengue serotypes might be discovered in the future.
Ideally, any vaccine for dengue must take into account the four original strains.
Signs & Symptoms
According to Eurosurveillance, a journal on epidemiology and infectious diseases, as high as 80% of dengue infections are asymptomatic—where the person concerned isn’t even aware of the infection. This makes possible dengue transmission through blood transfusions and organ transplantation, albeit rarely.
However, in those cases where dengue infections come with symptoms, these usually begin 4-7 days after the mosquito bite. Dengue is usually attended by:
Early dengue fever rash
Sudden onset high fever (40°C)
Headache (often on the forehead)
Fatigue
Swollen lymph glands
Pain behind the eyes (Eyes become painful to move.)
Pain in the legs, lower back and joints (Dengue fever is also called “breakbone fever” because of the associated pains experienced.)
Nausea and vomiting
Skin rash (Often appearing on the legs and chest.)
Dengue hemorrhagic fever
This a serious progression of dengue which, in addition to all the previously mentioned symptoms, has the following critical signs:
Severe abdominal pain
Pale and cold skin
General restlessness and irritability
Difficulty breathing
Bleeding from the nose, mouth or gums
Frequent vomiting with blood
Blood in the urine
Blood in the stool (dark stool)
The bleeding is caused by a low platelet count. This is because the dengue virus suppresses the production of platelets (or thrombocytes) in the bone marrow. In addition, available platelets that come into physical contact with infected blood cells are damaged and destroyed.
A healthy individual will have 150,000-450,000 platelets per microliter of blood. In cases of dengue hemorrhagic fever, platelet count could go as low as 20,000. The low platelet count leads to bleeding because one of the functions of thrombocytes is to facilitate blood clotting.
Regular monitoring of the patient’s platelet levels should be done even when the fever has come down. (High fever could return 24-48 hours after it has initially subsided.)
Dengue Shock Syndrome
This is the most critical progression of the dengue virus and is seriously life-threatening. Dengue Shock Syndrome is characterized by severe bleeding, weak but rapid pulse, and low blood pressure. These signify a collapse in the circulatory functions of the blood and could lead to multi-organ failure. Without the appropriate medical treatment, it could prove fatal within 12-24 hours.
Treatment
As of this writing, there is no specific antiviral treatment for dengue. Doctors provide relief by treating the symptoms and giving the patient supportive care.
Paracetamol and acetaminophen, and other painkillers are usually prescribed for the fever and pain. On the other hand, aspirin, ibuprofen and naproxen sodium are avoided at all costs. These have been shown to increase the chances of bleeding.
Frequent vomiting and a high temperature may cause dehydration, so plenty of fluid intake is vital. For some patients, intravenous fluid, rehydration salts or electrolyte replacement might be recommended. With plenty of rest and supportive care alleviating the symptoms, the patient is expected to recover in a couple of days.
For severe dengue cases where bleeding has occurred and platelet count is significantly below normal, a blood transfusion may be required to replace blood loss. The patient’s blood pressure, temperature and platelet count must be closely monitored.
Preventing Dengue
One can avert dengue by preventing mosquito bites. Here are some things you can do to prevent infection:
Eliminate standing water around your house.
Wear protective clothing such as long sleeves and long pants.
Apply mosquito repellant lotion or spray to the exposed parts of body. (You can also treat clothes with repellant)
Eliminate standing water. Prevent mosquitoes from laying her eggs by clearing home environs of water puddles which are known breeding grounds for Aedes aegypti.
Spray your home and surroundings with mosquito killer.
Stay indoors and ensure that screens are free from holes or gaps.
Stay away from moist and shaded areas where mosquitoes usually congregate.
Avoid shrubbery, tall grasses, planters and pots.
A person infected with dengue should be protected from further mosquito bites, especially in the first week of infection. A mosquito biting an infected person can spread the virus by biting another individual.
Without proper care, dengue can lead to a potentially serious condition. If you suspect any of your family member of contracting the virus, have him or her promptly screened.
BloodWorks Lab can help you with your blood test needs. We provide dengue screening (NS1 Ag + IgG/IgM) in addition to other routine blood tests.
We are also proud to be the first laboratory in the Philippines to also offer neurological tests like the Anti-NMDA Receptor Antibody Test and the Anti Acetylcholine Receptor (lgG) Antibody Test.
BloodWorks Lab is your one-stop shop for all your blood test needs. Our branches are in Alabang and Katipunan.