February 15, 2016 (Vol. 36, No. 4)
Researchers Looking at a Clever Microbial Countermeasure to Stop the Virus’ Spread
In early October, a team of scientists at the University of Wisconsin–Madison and Universidad de Sucre in Colombia ran the first assays confirming the presence of Zika virus (ZIKV) transmission in the South American country. In a recently published study the researchers documented a disease trajectory that started with nine positive patients and has now spread to more than 13,000 infected individuals in Columbia.
“Colombia is now only second to Brazil in the number of known Zika infections,” stated senior study author Matthew Aliota, Ph.D., an assistant scientist at the UW–Madison School of Veterinary Medicine.
The findings from this study were published online recently in Emerging Infectious Diseases through an article entitled “Detection of Autochthonous Zika Virus Transmission in Sincelejo, Colombia.”
ZIKV is transmitted to humans by Aedes mosquitos (primarily Aedes aegypti) and typically causes illness that is often indistinguishable from other viral infections, with symptoms such as fever, rash, and joint pain. Officials estimate that four out of five people who contract the virus do not get sick, and the virus is rarely fatal. However, a recent alarming find has uncovered that pregnant women in Brazil infected with ZIKV have given birth to babies with small heads and underdeveloped brains, a condition called microcephaly.
“If you’re pregnant or planning on being pregnant, absolutely cancel your vacation,” remarked Dr. Aliota, echoing the Centers for Disease Control and Prevention warning that pregnant women should not travel to the more than 20 countries now known to have active Zika transmission, like Brazil, Colombia, Ecuador, and many places in the Caribbean.
In the current study, the investigators tested samples from 22 patients for the genetic fingerprints of ZIKV, dengue, and chikungunya viruses. Nine of the samples tested positive for ZIKV, and now 13,500 cases have been identified in Colombia. The researchers’ findings underscore the need for better, more accurate laboratory diagnosis of ZIKV.
Dr. Aliota noted that “the symptoms of Zika virus are really nonspecific, and it overlaps with a lot of things, especially with dengue virus and chikungunya. It’s hard when someone comes in with a fever and a rash to narrow it down.”
The identification of ZIKV is only one part of the research teams’ goal, as they have also begun to look at various methods to control the spread of the virus. ZIKV is similar in its molecular make-up to dengue and chikungunya viruses—which are also spread by the Aedes mosquitos.
One interesting vector control approach that the scientists are looking at is the use of the Wolbachia bacteria, which is not naturally found in the Aedes aegypti mosquito. However, researchers with Eliminate Dengue—an international group charged with efforts to control the spread of dengue virus—have found that when they infect mosquitoes with the bacteria in the lab, it prevents them from transmitting dengue, chikungunya, and yellow fever.
“The Eliminate Dengue Program is doing field experiments to see if we will be able to replace existing wild-type populations of mosquitoes with these Wolbachia-infected ones and does it block dengue transmission?” Aliota says. “Now, we’re going to start looking at how that might be used for Zika virus control as well in South America.”
Dr. Aliota and his team are hopeful that their efforts will lead to a better understanding of ZIKV transmission and toward faster, more accurate diagnostic tests in the near future.