Contagion’s Top Five Zika-related news stories over the past year are included in this article.
The Zika virus has been circulating Brazil since 2015. Since then, the South American country has reported an increasing prevalence of babies born with microcephaly, a deformation characterized by small head size. In the United States, however, Zika virus infection was not a concern until 2016, when the virus was shown to have travelled north from South America into North America. The threat increased when US residents returned from trips to Zika-endemic regions with the virus. With mosquito season on the horizon, it was evident that action was necessary to stop travel-related cases from infecting local mosquito clusters with the Zika virus, which would potentially cause localized Zika outbreaks. Then, on July 29, 2016 the Centers for Disease Control and Prevention (CDC) confirmed that an area in South Florida was experiencing active Zika virus transmission since earlier that month. Read on for Contagion’s list of Zika-coverage from 2016.
In September 2016, the Singapore Ministry of Health confirmed that the country was seeing an increase in cases of Zika virus infection. Nonetheless, the virus was not new to the region.
Hoe Nam Leong, MBBS, infectious disease specialist at Mount Elizabeth Noveno Hospital in Singapore stated, “Zika has been around since the 1960s. The laboratories in Ministry of Health and Ministry of Environment have been doing surveillance on this illness for several years, and we have not isolated Zika in patients or in mosquitoes [until now] … We suspect a significant mutation occurred that conferred [the virus] an advantage in spreading from person to mosquito to person. Previously, reports of Zika [here] are far and few in between.”
The strain currently circulating in the region is closely related to the ones found in French Polynesia and Brazil, although it is not an exact match. According to Leong, the strain is more closely related to a Zika virus strain that was behind a Zika outbreak in Yap in 2007 and was circulating Thailand since 2012. In the same week that Singapore confirmed circulation of the Zika virus, Thailand officials began charging homeowners who did not clear their properties of potential mosquito breeding grounds with either a fine or jail time.
Singapore has confirmed 457 Zika cases since the start of the outbreak.
Researchers from São Paolo State University, found that epigallocatechin, a polyphenol found in large amounts of green tea, can block a Zika virus strain from entering host cells. Their findings were published in Virology in July.
Using a Brazilian strain of the Zika virus, researchers infected cells in a cell culture system in their lab. The virus was then mixed with varying concentrations of epigallocatechin, and those mixtures were added to the cells within the lab. The researchers found that concentrations of 100 μM or greater were successful in preventing more than 90% of the Zika virus from entering the cells.
It’s been proven that epigallocatechin can block many other viruses, such as HIV, the same way it does Zika. Epigallocatechin has proven to be safe when administered to healthy individuals, and to pregnant women; however, more studies are needed to assess the safety of epigallocatechin for clinical use.
Congenital infection with the Zika virus was believed to be only harmful to the developing fetus during the first trimester. However, in early April, CDC officials confirmed that infection during the second trimester may be just as harmful, and perhaps even in the third trimester as well.
According to Anthony Fauci, MD, director of the National Institute of Allergy and Infectious Diseases (NIAID), in a controlled study, pregnant monkeys infected with the virus were found to have exhibited viremia for significantly longer periods than those monkeys that were not pregnant. Similarly, a woman from Washington was found to have the Zika virus in her blood for up to 3 weeks. Normally, a virus lasts in the blood for days.
Dr. Fauci delved further into the neurological complications that may result from congenital Zika infection. He stated, “In Vitro studies of getting the virus and putting it in neural stem cells, [show] that it has very strong propensity to destroy tissue, which could explain why, besides interfering with the development of the fetus, it might directly attack brain tissue even when the fetus is later on in the period of gestation.”
In mid-April, the CDC confirmed that, in addition to sexual transmission of Zika virus through vaginal sex, Zika can be transmitted through anal sex. Additionally, a case involving this mode of transmission marked the first case of male-to-male transmission of Zika.
The first partner had recently travelled to Venezuela, a Zika-endemic region, where he acquired the infection. This individual had experienced Zika-like symptoms, such as rash, fever and conjunctivitis, and reported to have unprotected sexual intercourse with his partner one day before and one day after symptom onset. After one week, the second partner exhibited the following symptoms: fever, myalgia, headache, lethargy, and malaise. The individual then went on to develop a “slightly pruritic rash on his torso and arms, small joint arthritis of his hands and feet, and conjunctivitis.” These symptoms resolved for both patients.
The first case of Zika-induced microcephaly in the United States was reported in Puerto Rico in early May. This news came as the first Zika-related death was reported out of the island.
Microcephaly was detected in a male fetus that exhibited “severe microcephaly and calcifications in the brain accompanied by Zika-wide presence of the virus.” Aside from microcephaly, congenital infection with the Zika virus may result in stillbirth, excess fluid in the brain, retinal damage, and other neurological birth defects. At this time, the total count of Zika virus cases in Puerto Rico is 33,487.