Guest essay by Eric Worrall
The Australian Journal of Pharmacy has just tried to link climate change, to the terrifying Zika Virus outbreak in South and Central America. The Zika Virus, a mosquito born disease, has been implicated in an upsurge of serious birth defects.
CLIMATE CHANGE COULD WORSEN DISEASES LIKE ZIKA VIRUS
The news of an outbreak of the Zika virus in South America is a grim reminder of the health hazards associated with a warming world, Climate and Health Alliance Executive Director Fiona Armstrong said today.
A study published in the journal Emerging Infectious Diseases this week documents the spread of the virus in Columbia, while Brazil is experiencing the largest known outbreak of Zika virus, which is being linked to the deaths of babies affected by microencephaly, or abnormally small brains.
“Regions with increasing average temperatures are at increased risk of mosquito-borne diseases, as mosquitoes thrive in and move to warmer regions,” says Armstrong.
The abstract of the referenced study;
Zika virus (ZIKV) is an arthropodborne member of the genus Flavivirus of the Spondweni serocomplex and is transmitted by Aedes mosquitoes (primarily Ae. aegypti in urban and periurban cycles). ZIKV emerged in Africa and has caused outbreaks of febrile disease that clinically resemble dengue fever and other arboviral diseases (1) but has been linked to neurologic syndromes and congenital malformation (2). Outbreaks have been reported in the Yap islands of the Federated States of Micronesia (3), French Polynesia (4), and Oceania; Brazil is currently experiencing the first reported local transmission of ZIKV in the Americas (5).
The future spread of ZIKV is unpredictable, but the history of ZIKV has been reminiscent of chikungunya virus (CHIKV), which reemerged in Africa and now circulates on all inhabited continents and is a major global health problem. ZIKV has been found in Colombia and is likely following the path of CHIKV, which reached the country in August 2014 (6). The virus co-circulates with other Ae. aegypti–transmitted arboviruses, including dengue virus (DENV) and yellow fever virus. We report ZIKV infection in Colombia and a recent ongoing outbreak in Sincelejo, Colombia, with resulting illness characterized by maculopapular rash, fever, myalgia/arthralgia, and conjunctivitis.
During October–November 2015, a total of 22 patients received a presumptive diagnosis of an acute viral illness by emergency department physicians at the Centro de Diagnostico Medico-Universidad de Sucre in Sincelejo. The patients began treatment for a dengue-like illness, and blood samples were obtained for diagnosis. The samples were analyzed at the Universidad de Sucre by using reverse transcription PCR (RT-PCR) to detect DENV, CHIKV, or ZIKV. Viral RNA was extracted from the serum samples by using the ZR Viral RNA Kit (Zymo Research, Irvine, CA, USA); reverse transcription was performed by using the Protoscript First Strand cDNA Synthesis Kit (New England Biolabs, Ipswich, MA, USA). Amplicons were produced by using the OneTaq Quick-Load 2X Master Mix (New England Biolabs) with primers specific to DENV (7), CHIKV (forward: 5′-CGCCAACATTCTGCTTACAC-3′; reverse: 5′-AGGATGCCGGTCATTTGAT-3′), and ZIKV. The CHIKV amplification target was 649 bp of nonstructural protein 1 (NS1). A positive PCR for a partial region of the envelope (E) gene with primers ZIKVENVF and ZIKVENVR (8) was considered indicative of ZIKV infection. ZIKV primers specific for the E gene and NS1 were designed and used to amplify the E gene and NS1 for phylogenetic analyses, and amplicons were produced by using the OneTaq One-Step RT-PCR Kit (New England Biolabs). E gene and NS1 PCR products were sequenced at the University of Wisconsin–Madison Biotechnology Center (Madison, WI, USA).
Thumbnail of Majority-rule consensus tree based on Zika virus envelope and nonstructural protein 1 gene sequences (2,604 nt) of isolates from patients in Sincelejo, Colombia, October–November 2015, compared with reference isolates. The tree was constructed on the basis of Bayesian phylogenetic analysis with 8 million generations and a general time-reversible substitution model using MrBayes software version 3.2 (http://mrbayes.sourceforge.net). Numbers to the right of nodes represent posterior p
Samples from all patients were negative by RT-PCR for DENV and CHIKV; samples from 9 (41%) patients were positive for ZIKV. Among those 9 patients, 7 (78%) were male; median age was 23; and none had a history of international travel. ZIKV was analyzed by sequencing the E gene and NS1 of 2 isolates. Phylogenetic analyses rooted with Spondweni virus showed that the ZIKV sequences belonged to the Asian lineage (Figure) and were closely related to strains isolated during the 2015 outbreak in Brazil (5). The sequences also showed 99% identity with sequences from a ZIKV isolate from French Polynesia (GenBank accession no. KJ776791) (9). These data suggest that ZIKV circulating in Colombia could have been imported from Brazil, most likely as a result of tourism activities on Colombia’s northern coast, where the first reported case was identified (the state of Bolivar).
We report ZIKV infection in Colombia in association with an ongoing outbreak of acute maculoexantematic illness. Since detection of ZIKV in Sincelejo, a total of 13,500 cases have been identified in 28 of the country’s 32 territorial entities (10), all of which have abundant populations of Ae. aegypti mosquitoes and co-circulation of DENV and CHIKV. These circumstances highlight the need for accurate laboratory diagnostics and suggest that monitoring whether the virus spreads into neighboring countries (e.g., Ecuador, Peru, Venezuela, and Panama) is imperative.
Erwin Camacho, Margaret Paternina-Gomez, Pedro J. Blanco, Jorge E. Osorio, and Matthew T. AliotaComments to Author
Author affiliations: University of Wisconsin–Madison, Madison, Wisconsin, USA (E. Camacho, J.E. Osorio, M.T. Aliota); Universidad de Sucre, Sincelejo, Colombia (M. Paternina-Gomez, P.J. Blanco)
It is true that Aedes Aegypti, the mosquito which carries Zika, lives in tropical and subtropical regions. Global warming, if it occurs, might increase the range of Aegypti. But there are close relatives of Aegypti, such as Aedes Albopictus, which might be just as dangerous. Albopictus has a much greater range than Aegypti, but carries similar viral diseases to Aegypti. I don’t know whether Albopictus can carry Zika, but this has to be considered as a significant possibility.
Albopictus is currently spreading through temperate zones in Europe, and has been detected as far North as Germany.
Even if it turns out only Aegypti can carry Zika, I doubt the most efficient response to dangerous mosquito borne diseases is to build a few wind turbines.
A good start to controlling mosquito borne diseases, might be to remove the pointless bureaucratic obstacles to spraying DDT, one of the most effective anti-mosquito chemicals ever developed.
Use of DDT was almost outlawed after vigorous scare campaigns by green groups, but this much maligned chemical is harmless to humans. Professor Kenneth Mellanby, who campaigned for the use of DDT in the 1940s, used to eat a substantial pinch of concentrated DDT as part of his demonstration. Mellanby did not suffer any health problems from his massive consumption of DDT – he died in 1993, at the age of 85 years.
Part of the reason DDT was and is so popular in the third world, is DDT is very easy to produce, a simple one step reaction any backyard lab could perform. With a few litres of precursor chemicals, an amateur laboratory could produce enough DDT for thousands of treatments. I suspect if authorities don’t remove bureaucratic obstacles to DDT use, people in Zika affected regions might start cooking their own.