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Public health emergency persists as Zika virus spreads

The Zika virus is a mosquito-borne pathogen that was identified in humans over 60 years ago in parts of East Africa, according to the World Health Organization. This may surprise some people since serious health concerns surrounding the virus have recently come to light.

Margaret Chan, the director-general of WHO, announced the Zika virus to be a “public health emergency of international concern” in the beginning of February due to the virus’s rapid spread across the Americas and its suspected relationship with microcephaly and other neurological effects.

Active infections have been confirmed in Africa, the Americas, Asia and the Pacific. It cannot be determined where the virus will strike next.

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A dangerous creature

Mosquito-borne diseases kill over one million people worldwide per year and cause other types of human distress, according to the American Mosquito Control Association.

Aedes mosquitoes are responsible for the transmission of the Zika virus, as well as other dangerous pathogens.

These aggressive daytime biters are most active in the early morning, late afternoon and into the early evening.

Aedes mosquitoes thrive in tropical and subtropical climates with warm, humid conditions to lay their clusters of eggs.

This wet environment is needed for the eggs to hatch into larvae. Metamorphosis is triggered after significant growth of the larvae, transforming it into a pupa, which is a cocoon-like structure. A new adult completes the life cycle by breaking out of the pupa. The process takes about 8-10 days, depending on temperatures, according to the Centers for Disease Control and Prevention.

Gender plays a huge role of the habits of the mosquito. Male mosquitoes only feed on fruit, whereas females include blood in their diet to help mature their eggs. Females, therefore, are the primary carriers of this harmful pathogen.

Every mosquito-borne pathogen has a range of species that can transmit a particular virus, depending on “the biology and dynamics of the specific mosquito [species],” said Dr. Kacey Ernst, an associate professor for the UA Epidemiology and Biostatistics Department in the Mel and Enid Zuckerman College of Public Health.

The mosquito has to survive the incubation period of the virus in its own body before it can further transmit the infection to another organism through its saliva. According to Ernst, it takes approximately one week for the virus to migrate to the mosquito’s saliva glands.

Other modes of Zika virus transmission are still under investigation by researchers around the world, such as sexual contact and blood transfusion.

Unanswered questions

Only about 20 percent of Zika-infected people develop symptoms that last several days to a week, according to the CDC.

Symptoms include: headaches, fever, rash, joint and muscle pain, and conjunctivitis (red eyes).

The Zika virus was not considered a public health threat until the puzzling increase in the number of microcephaly cases in the northeast region of Brazil during recent months.

Microcephaly is a rare birth defect characterized by an unexpectedly small head compared to other babies of similar age and sex.

This condition correlates with the failure of proper brain development, movement and feeding problems, as well as other health problems, ranging from mild to life-threatening. The reasons for most cases of this birth defect are still unknown.

As of the end of January, there were more than 4,000 cases of microcephaly and other nervous system disorders reported by the Ministry of Health of Brazil, which is at a dramatic increase from the average of 163 per year nationwide, according to the Zika Situation Report by WHO.

Even though these cases are associated with the Zika virus through time and location, more research is required to determine and understand the possible connection.

Some countries are even recommending that women delay pregnancy plans for up to two years as a precaution.

“We [the scientific community] are desperate to find the answers to these questions,” Ernst said regarding the many unanswered questions concerning the correlation between the virus and neurological birth defects.

A window of opportunity

Local transmission of the virus has yet to reach the United States. Yet, populations of Aedes mosquitoes capable of carrying the Zika virus exist in the southern part of the country, making it a prime target for the virus’s next strike.

The United States has “a window of opportunity right now,” Ernst said, “because of the cooler temperatures compared to the tropical climate of South America to prevent the spread of the virus into the country [and] prepare for it to cross the U.S. border.”

“[There is] a nice dip in mosquito populations in the United States,” Ersnt said, which helps control these mosquito-borne pathogens.

Mosquitoes are a difficult organism to control. Programs rely on community participation to eliminate habitats for eggs to hatch, such as standing water in pots or tires.

Adulticide, a pesticide designed to kill adult insects, not their larvae, can be sprayed in the early morning hours to prevent mosquito bites.

Genetically modified mosquitoes are also a potential control technique. This technique creates sterile male mosquitoes in the laboratory still capable of mating with wild females. The key is the eggs laid by the wild female cannot mature, reducing the number of new mosquitoes able to transmit the virus.

There is currently no cure or vaccine for the Zika virus. The CDC has issued travel warnings for travelers to Zika-infected regions until further notice.

For now, bug repellent is your best friend.


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UA COVID-19 Test Tracker

Daily (9/21)
993 29 2.9%
Total (8/2)
23,557 463 2.0%
Includes tests since August 2, 2021
Data from https://covid19.arizona.edu/updates
Updated September 21, 2021