THE QUARTERLY PUBLICATION OF THE AMERICAN COLLEGE OF OSTEOPATHIC PEDIATRICIANS
Spring 2016 Issue
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Editor's Corner
Zika Virus Outbreak
By Robert G. Locke, DO, MPH, FACOP
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Robert G. Locke, DO, MPH, FACOP |
Zika virus, the latest tropical Flavivirus to cause an outbreak in the Americas, is associated with a 20-fold increase in microcephaly in Brazilian newborns and a 10- to 20-fold increase in Guillen-Barrie Syndrome. The CDC, and its European counterpart ECDC, have issued strong travel warnings targeting pregnant women and children. The Brazilian military has been mobilized to eradicate the Aedes mosquito.
An increasing spread of mosquito-borne illnesses (Zika, Dengue, Chikungunya, Mayaro, Ross River, Barmah Forest, O’nyong-nyong and Sindbis viruses) with symptoms that overlap with malaria, measles, group A streptococcus, leptospirosis, parvovirus, enterovirus, and adenovirus, create a challenging differential diagnosis for the primary care pediatrician. Previously, a history of overseas travel helped focus the diagnosis. The majority of tropical diseases diagnosed within the US are associated with a history of overseas travel. Just 12 of the 3500 cases of Chikunygunya diagnosed within the US have been acquired locally.
This is changing. Weather patterns, human behavior and economics alter exposure. In Brazil, the Zika virus epidemic was initiated in part by an influx of tourists for international sporting events, altered weather patterns, a drought and distributive economics. The Brazilian drought led to the collection of rainwater in open cisterns and buckets. The high poverty status of many Brazilians results in the absence of access to personal and regional anti-mosquito practices. The upcoming 2016 Summer Olympics will be held in Rio de Janeiro, creating further international travel exposure to Brazilians and international tourists.
In the US, air-conditioning, screened windows, anti-mosquito bug spray use, and mosquito-reduction water practices are standard or can be rapidly upscaled to help prevent viral transmission. However, because of a warming climate, the Aedes mosquito that carries Zika and other viruses can now be found not just across the southernmost regions of the United States, but up into the midwest and Great Lakes region and across to the northeastern seaboard. Infection of mosquito-borne tropical illnesses without overseas travel may soon be a risk for a substantial portion of the United States.
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| 1 | Human case of Zika virus worldwide in 2007 |
| > 1 million | Human cases of Zika virus in Brazil in 2015 |
| 3,500 | Suspected cases of Zika virus-associated microcephaly in Brazil (2015) |
| >147 | Cases of microcephaly in Brazil prior to the Zika virus outbreak (2014) |
| 20x | 20-fold increase of Guillain-Barré syndrome cases in Zika virus outbreak regions |
| 20% | Clinical symptoms in Zika virus infected adult individuals |
| 0 | Commercially available Zika diagnostic assays (as of 2-01-2016) |
| 0 | Specific anti-Zika viral agents |
| 46/56 | United States (including territories and District of Columbia) in which the Aedes albopictus (Asian Tiger mosquto) lives. Experimental evidence this mosquito may also carry the Zika virus. |
| $8 | Cost of a nine-ounce bottle of insect repellent (safe during pregnancy)
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| $10 | Cost of a mosquito net (personal or to give to charity) |
The Zika virus was originally detected in a Rhesus monkey in 1947 and has been slowly spreading from across the Pacific. The first human diagnosis was in 2007. Eight years later there is a suspected caseload of 1.5 million in Brazil alone. It is unusual for related viruses to cross the placenta and cause fetal infection. Fetal infection has been diagnosed within the US. There have been cases of infection through sexual contact (the Zika virus is present in semen and saliva) and through blood product transmission. The current epidemic in the Americas is suspected to reflect a recently changed Zika virus, possibly as a result of cross-contamination with other viruses.
Diagnosing Zika can be difficult. There are no commercial assays, and in regions where dengue is endemic, the vaccine or a previous infection, antibody cross-contamination can lead to false positive Zika virus test result with some assays. Vaccine, specific viral treatment, and improved diagnostic methods are all under investigation.
There are successes in reducing tropical illnesses. Due to public health measures and improvements in standard living conditions, malaria and other mosquito-borne illnesses were far more common in colonial Boston and Savannah than today. With a massive effort, Ebola has been temporarily contained. However, physicians and the public can become fatigued with dire warnings of the next panepidemic. Few, if any areas of the US, have the funding or infrastructure to optimally manage a massive infectious outbreak. Wishing for a changed local and worldwide political and economic behavior is a poor starting point for a planned response.
With the ease of international travel, changing climate, variable standard of living contexts, economic resource limitations and politics, the scientific community needs to be smarter in creating a prevention and response strategy that is actionable within real world constraints rather than trying to change the political-economic context in which a response plan will be employed. In the meantime, pediatricians can find the latest information about Zika and related insect-related illness at the CDC website. CDC resources for healthcare providers at http://www.cdc.gov/zika/hc-providers/index.html.
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