by Jims Vincent Capuno
It’s touted to be the “country’s public enemy number one.” More people have died from dengue than at the hands of criminal elements. In Davao City, for instance, 14 deaths from January to June this year due to dengue have been reported, according to the city health office. In the same span of time, 1,312 had contracted the disease.
Dengue has replaced malaria as the most important mosquito-borne viral disease in the world, infecting about 50 million people each year.
There are four types of dengue viruses (DEN-1, DEN-2, DEN-3, and DEN-4), all of which can cause serious illness. Doctors say infection by one virus does not offer protection against the other three. Dengue viruses of multiple types are now endemic in most countries in the tropics, the World Health Organization (WHO) reports.
The virus is carried and transmitted by the Aedes aegypti mosquito, which is sometimes called tiger mosquito because of its peculiar white stripes on its legs and back. At first glance, it may not be dangerous. But it can kill, as medical reports show.
When the dengue-carrying mosquito gorges on the blood of an infected human, the virus enters the insect’s salivary gland, where it incubates for eight to ten days. After that, the mosquito can pass the virus on to the next person it bites.
Like other mosquito species, only the female Aedes bites. The adult female mates and takes its first blood meal about 48 hours after coming out of its pupa stage. It can bite several people, depending on how much blood it sucks. Its bite is deadlier two hours after sunrise and before sunset.
“An infected mosquito is capable of transmitting the virus to susceptible individuals for the rest of its life – about three weeks – during probing and blood feeding,” explains Dr. Simon Ng, a pediatrician at the Mount Elizabeth Medical Center in Singapore.
Once the virus enters the body, it multiplies slowly in blood cells. “A person bitten by a dengue-carrying mosquito does not immediately show symptoms,” says Professor Zulkifli Ismail, a Malaysian pediatrician. “It takes from five to seven days for the virus to incubate.”
Symptoms vary according to the age and health of the patient. Generally, the sickness starts with a high temperature, rash, agonizing headache, and muscle and joint pain. Nausea, vomiting, and loss of appetite are common, and a rash usually appears three or four days after the fever starts. The worst symptoms can last up to ten days, and complete recovery can take a month.
But the deadlier form is the dengue hemorrhagic fever (DHF). First recognized during the 1950s, it is today a leading cause of death in children in many countries. The Philippine Journal of Pediatrics reported of a DHF epidemic in the country in 1953-54.
Both dengue fever and DHF are caused by the same viruses. “You either have a milder dengue fever or a more serious DHF,” explains Dr. Eric Tayag, one of the country’s dengue experts. “Dengue fever does not develop into DHF!”
In DHF, cells release chemicals that trigger leakage of plasma from blood vessels. “Fluids accumulate in body cavities, causing profound shock,” explains Dr. Lulu Bravo, a professor at the University of the Philippines College of Medicine. “Death often results from bleeding in the brain, intestines or other organs.” Adds Prof. Zulkifli, “After a dengue patient has gone into shock, it’s usually a matter of time before multi-organ failure occurs and death becomes inevitable.”
This terrifying scenario is characterized by high continuous fever (40-41 degrees) lasting up to seven days that may be accompanied by loss of appetite, nausea, vomiting, abdominal pain, and bleeding from the skin, nose, or gums. In the worst cases, the patients’ condition may suddenly deteriorate after a few days of fever, and they may die within 24 hours. [Jims Vincent Capuno]
