Sunday, March 7, 2021

Medical officer of health discusses Zika virus

The World Health Organization (WHO) announced a “public health emergency of international concern” earlier this week regarding the Zika virus. The Sydenham Current caught up with Dr. David Colby, the medical officer of health in Chatham-Kent, to fill us in with details about the disease.

“Zika virus was discovered in the Zika forest in Uganda, Africa in 1947,” Colby said.

“It is related to dengue and yellow fever and is common in Africa and Asia where the population has a high level of immunity. It is spread by Aedes mosquitoes which are daytime biters. A few sexually transmitted infections have also been documented. 80% of Zika virus infections are asymptomatic but some people get mild fever, skin eruptions, joint pains and conjunctivitis (red eyes).”

There is no specific treatment or vaccine currently available for the Zika virus, Colby said.

“In May 2015 Zika virus was reported to be spreading in Brazil for the first time,” he said.

“In October 2015 a surge in cases of microcephaly (failure of the brain and skull to grow and develop properly) was reported in Northern Brazil. Brazil has about 3 million births per year and about 150 cases per year of microcephaly typically occur. Brazil has reported that it is currently investigating almost 4,000 cases.”

Colby added: “This is an alarming increase but the link to Zika virus infection has not been proved to be causal at this point. There has not been a surge of microcephaly cases anywhere but Brazil.

The WHO called an emergency meeting on February 1 and declared Zika virus to be a global public health emergency.

“Zika virus is spreading rapidly in Latin America and the Caribbean and many holiday destinations for Canadians have documented the presence of Zika virus, including but not limited to Mexico, Guatemala, Honduras, El Salvador, Costa Rica, Panama, Curacao, Haiti, Dominican Republic, Puerto Rico, Saint Martin, Guadeloupe, Martinique, US Virgin Islands and Barbados,” he said.

“It is likely that nearby islands and regions will be affected soon if they are not already.”

Colby said the US Centers for Disease Control (CDC) has advised that pregnant women in all trimesters and women trying to become pregnant avoid travel to Zika virus affected areas and if in affected areas use scrupulous anti-mosquito measures.

“It is likely that if Zika virus is causing these cases of microcephaly, the fetuses of mothers who catch Zika virus for the first time in early pregnancy would be at highest risk,” Colby said. “As some women may not realize they are pregnant until travelling, there is a great deal of concern in the community. Some airlines are offering cancellations and destination changes without penalties.”

Colby said microcephaly is reliably detected by ultrasound examination at around 25 weeks gestation, the end of second trimester.

“CDC is recommending that all pregnant women who have travelled to Zika virus areas during pregnancy consult their physician and have an ultrasound screening,” Colby said.

“Only if symptoms of Zika virus infection (fever, skin eruptions, joint pains and conjunctivitis (red eyes)) were experienced during or within two weeks of travel to an affected area are blood tests for Zika virus advised at this time.”

The WHO has also released some information about prevention and treatment of the Zika virus:


Mosquitoes and their breeding sites pose a significant risk factor for Zika virus infection. Prevention and control relies on reducing mosquitoes through source reduction (removal and modification of breeding sites) and reducing contact between mosquitoes and people.

This can be done by using insect repellent; wearing clothes (preferably light-coloured) that cover as much of the body as possible; using physical barriers such as screens, closed doors and windows; and sleeping under mosquito nets. It is also important to empty, clean or cover containers that can hold water such as buckets, flower pots or tyres, so that places where mosquitoes can breed are removed.

Special attention and help should be given to those who may not be able to protect themselves adequately, such as young children, the sick or elderly.

During outbreaks, health authorities may advise that spraying of insecticides be carried out. Insecticides recommended by the WHO Pesticide Evaluation Scheme may also be used as larvicides to treat relatively large water containers.

Travellers should take the basic precautions described above to protect themselves from mosquito bites.


Zika virus disease is usually relatively mild and requires no specific treatment. People sick with Zika virus should get plenty of rest, drink enough fluids, and treat pain and fever with common medicines. If symptoms worsen, they should seek medical care and advice. There is currently no vaccine available.

For more information call the Chatham-Kent Public Health Unit at 519-352-7270 or visit them online at

– Photo credit: James Gathany, CDC – The proboscis of an Aedes albopictus mosquito feeding on human blood.

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