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Friday, September 18th, 2020

Mosquitoes ‘public health enemy number one’

by November 7, 2016 General

THE Department of Health (DOH) said that all the 19 known cases of Zika virus infection in the Philippines were caused by mosquito bites, and is stepping up efforts to fight the disease that has affected more than 160 thousand people worldwide this year, it said in a briefing last week.

The most recent cases as of October 28 are from Cavite, a young male and a middle-aged female, the DOH reported.

“They are at home,” said Enrique Tayag, spokesperson of the DOH during the first National Summit on Zika Virus Disease.

Like the other cases, they did not need confinement.

Zika Virus Disease (ZVD) or simply Zika is a mild disease mainly transmitted through mosquito bites, although it can also be transmitted from person to person through sexual activity or blood transfusions.

It has caught attention of Filipinos since this year’s index case in Iloilo City was reported on September 5.

The next two reported cases of Zika were from the same household.

To date, the majority of confirmed cases are from Iloilo City.

Regional breakdown of the four affected regions are 12 in Western Visayas, three in Calabarzon (Cavite, Laguna, Batangas, Rizal, Quezon), three in National Capital Region (NCR), and one in Central Visayas.

All these cases belong to the 20 percent of people who are symptomatic, while the majority, or four out of five cases do not show symptoms or are asymptomatic, meaning that the number of people infected could actually be much higher.

Common symptoms include rash, conjunctivitis, joint pain, and fever.

Among those four, studies showed that rash is the most common symptom in all affected countries.

Despite the huge percentage of asymptomatic cases, the DOH said only those that manifest the symptoms are tested, and only 19 have been positive so far.

Urine and blood samples from symptomatic patients are tested at the Research Institute for Tropical Medicines (RITM).

RITM Representative Dr. Socorro Lupisan said there are 7,000 test kits available to test 3,500 people because two samples are taken from each patient—urine and blood.

“We do test suspects for the three (Zika, Dengue and Chikungunya),” said Lupisan.

However, due to constraints like the current test sensitivity, which was advised to be done during the seventh to the tenth day from the onset of illness, it is not advised to test even the asymptomatic cases.

Not only will it be impossible to know if you are on your seventh day if you show no symptoms it is also not practical, said Tayag.

Costs for these tests range from P4,000 to P6,000.

The test kits, and the materials and supply for vector surveillance were purchased through the P16.5 million that DOH provided for RITM.

Zika during pregnancy

Only one of the Philippines’ 19 confirmed cases is pregnant.

This 22-year-old case from Cebu was 19 weeks pregnant with her first baby when she was diagnosed with Zika.

From the time she contracted the disease until now, ultrasound showed no signs of fetal abnormalities in the central nervous system of the child.

DOH has been monitoring her for possible complications resulting in microcephaly, or the abnormally smaller size of the head and the brain of a child.

Records of mircocephaly linked to Zika contracted during pregnancy are evident in other countries, with Brazil having the largest number of cases.

Despite the risk, Tayag said based on a study only one to three percent of pregnant Zika cases result in microcephaly.

“It is considered rare,” said Tayag.

The same study pointed out that the risk is negligible in the second and third trimester.

The case in Cebu got infected during her second trimester, but because it is the first pregnant case reported in the country, “monitoring will continue,” said Tayag.

Meantime, pregnant women are advised to avoid mosquito bites especially during the first three months of pregnancy.

Also, they are urged to either abstain from sex or practice safe sex through using condoms for protection.

Combat Zika through vector control

Aedes aegypti is considered public health enemy number one because it causes the majority of Zika transmissions worldwide.

This mosquito, which also transmits Dengue and Chikungunya, is endemic in the Philippines and other tropical and sub-tropical countries.

It is dubbed the ‘clean mosquito’ because it breeds in clean, stagnant water and not in esteros.

DOH has focused its efforts on vector control because all the locally confirmed cases have been transmitted via mosquito bites.

The department has been encouraging the public to be good citizens and practice the “4S”: Search and destroy mosquito-breeding sites through proper disposal of containers that may hold water; self-protection through using insect repellents; Seek early consultation when any of the symptoms appear; and Say yes to fogging when there is a clustering.

Meanwhile, Tayag told The Manila Times that the three new approaches in vector control discussed during the
week-long forum held at World Health Organization Regional Office in Manila last October are still being studied.

These approaches incapacitate mosquitoes from transmitting diseases.

One is through infecting them with wolbachia said Dr. Rabindra Abeyasinghe, an expert in vector-borne and parasitic disease.

Singapore started a six-month trial of this approach on October 18.

They released about three thousand male wolbachia-carrying aedes mosquitoes with an aim to let them mate with a female aedes to produce eggs that will not hatch, thus reducing their number.

Another is through genetic manipulation.

Last is sterilizing mosquitoes through x-rays.

DOH does not exercise any of these three yet because they “only use accepted technologies” like using insect repellents and fogging, Tayag told The Manila Times.

Tayag said these mosquitoes also play a part in the environment.

“They are just accidental microorganism-disease carrying mosquitoes,” he added.

He also pointed out that vector controls such as repellent patches or electric “zap” insect killers are considered largely ineffective.

Other infection paths

Unlike other viral diseases transmitted by aedes—Dengue and Chikungunya—Zika can also be transmitted in other ways.

Studies showed that the virus can be seen in blood, in semen, in vaginal fluid, and even in breast milk.
Records from other countries showed Zika cases from sexual transmission and blood transfusion.

This is why the DOH appeals to the public for the proper use of either or both male and female condoms throughout the entire intercourse.

The virus can be transmitted through vaginal, oral and anal sex, and even in the sharing of sex toys.
For now, only blood used in transfusion for pregnant women will be tested because testing of all blood used in transfusion is not practical, said health undersecretary Gerardo Bayugo.

Despite being evident in breast milk, there are so far no records of cases transmitted through it.
Bayugo pushed for self-protection because it is both personal and community protection.

“It’s not just self protection because if you don’t get infected you will not be part of those who can be the medium for spreading the disease,” said Bayugo.

He then said that DOH continues to improve their guidelines and update their action plans as they gather information on Zika.