Zika is the latest tropical mosquito borne virus to appear in America. While more closely related to West Nile virus the symptoms are like a mild case of dengue or chikungunya – usually a slight fever, headaches and sometime red eyes or mild joint pain. The disease is spread by day flying mosquitoes including Ae. aegypti and Ae. albopictus in Costa Rica South America, Central America and the U.S.
Zika is a mild viral infection. So mild in fact that 4 out of 5 people never even notice that they have the disease. This may be one of the reasons it is able to spread quickly. People who are unaware they are infected can pass the virus to mosquitoes which then pass it to other people without the carrier experiencing any illness. It is also spread by sexual contact with an infected partner.
Aedes mosquitoes are present across most of the Americas including the coastal swamps and lowlands of Costa Rica. They are more common in areas that humans inhabit and quickly establish in puddles formed in old tires, soda bottles etc.
The World Health Organization declared the virus a world health emergency and the safest assumption is that mosquitoes in the Americas are infected. It’s more important now than ever to avoid bites whether you are at home or traveling.
Prevention and Transmission of Zika
The best prevention is minimizing the number of mosquito bites. Limiting time outdoors especially around dawn and dusk, wearing long sleeves and an effective repellent containing DEET or Picaridin. Natural repellents like citronella and lavender oil smell nice but are considerably less effective.
There is no immunization. There is no cure. Treatment consists of bed rest.
Zika in Costa Rica
The Costa Rican government is intensifying mosquito eradication efforts started years ago to control Dengue outbreaks.
The health ministry is fogging with conventional pesticides to kill adults and larvae. They are also trying a new approach using Saccharopolyspora spinosa bacteria inoculated into water sources. The bacteria produces a natural pesticide which is toxic to mosquito larvae and thought to be harmless to humans.
The virus has been present in Costa Rica since at least December of 2015 when a U.S. tourist was exposed in Nosara. He was not diagnosed until January 2016 when he was back in the U.S. By the end of February 2016 two other cases of zika transmission had been found in Costa Rica both on the Nicoya peninsula.
UPDATE August 29, 2016 – A potential breakthrough for the treatment of Zika infections and prevention of microcephaly was reported today in one of the worlds leading scientific journals. Scientists from the U.S. National Institutes of Health, Johns Hopkins University and Florida State University reported discovering two existing drugs/compounds “that can both stop Zika from replicating in the body and from damaging the crucial fetal brain cells that lead to birth defects in newborns” in Nature: medicine.
One of the most exciting aspects of this discovery is that it’s possible it may lead to a viable treatment quite soon because one of the compounds is already approved and could shortcut the sometimes years long FDA approval process. According to FSU “One of the identified compounds is the basis for a drug called Nicolsamide, a U.S. Food and Drug Administration approved drug that showed no danger to pregnant women in animal studies. It is commonly used to treat tapeworm. This could theoretically be prescribed by a doctor today, though tests are still needed to determine a specific treatment regimen for the infection.”
UPDATE August 16, 2016 – A baby with microcephaly was born in Costa Rica to a Nicaraguan mother who contracted Zika in Nicaragua before moving to Costa Rica. This has generated headlines like “Microcephaly in Costa Rica” which are misleading to say the least.
UPDATE July 29, 2016 – Cases of mosquito transmission have been reported in Miami Florida. The U.K. has issued an advisory for British citizens considering travel to the southern U.S. “Pregnant women are advised to consider postponing non-essential travel until after pregnancy.”
UPDATE July 10, 2016 – Still good news. The numbers of individuals infected so far in the rainy season has been much lower than many predictions. A North Dakota man was confirmed as the second case of U.S. tourist contracting Zika in Costa Rica out of approximately a million visitors since the outbreak began.
A total of 159 cases were detected in Costa Rica in the first half of 2016 including 6 pregnant women. Zero cases of Guillain-Barré syndrome, zero cases of any neurological complications and zero cases with any indication of microcephaly have been reported.
In the U.S. a total of 1,133 cases of Zika have been detected. Five cases of associated Guillain-Barré syndrome have been reported but no evidence of microcephaly has been seen.
UPDATE June 17, 2016 – Some good news. News reports indicate that the number of new cases of Zika in Central American countries has decreased over the past month indicating that even though the rainy season has arrived in the region the mosquito control efforts seem to be having a big positive impact in controlling the spread of the disease. The Costa Rican Ministry of Health reports a total of about 100 cases in 2016.
UPDATE May 30, 2016 – The Costa Rican Ministry of Health updated the total number of cases of Zika transmission to 58. 44 new cases in Jacó were added to the previously known 5 in San José and 9 on the Nicoya Peninsula. Mosquito eradication efforts are being increased but cases are expected to continue to rise as the Pacific and central mountain rainy season begins.
The number of travel related cases detected in the U.S. is up to 503 (see current CDC map). Over 150 pregnant women have tested positive for Zika in the U.S. Congress has now reversed course from blocking funding for Zika prevention and treatment in late 2015 to now recommending $1.1 billion in new funding.
UPDATE May 1, 2016 – The BBC published an announcement that there may be risks of other brain injuries to fetuses exposed to Zika.
UPDATE April 25, 2016 – Canada announced the first case of Zika and New York announced a $21 million plan to fight mosquitoes and the virus.
UPDATE April 13, 2016 – The CDC (U.S. Centers for Disease Control and Prevention) has cited a New England Journal of Medicine article stating “we suggest that sufficient evidence has accumulated to infer a causal relationship between prenatal Zika virus infection and microcephaly” to add Zika to the list of causes which previously included other infections during pregnancy, such as rubella, toxoplasmosis, or cytomegalovirus, alcohol or drug abuse, and malnutrition.
In other words the CDC has stated that Zika infections during pregnancy can be a cause of microcephaly. The CDC has not changed any of their recommendations based on this conclusion.
UPDATE April 12, 2016 – The CDC (U.S. Centers for Disease Control and Prevention) reports 346 cases across 41 states in the U.S. and active mosquito borne transmission in every country from Mexico south through the Caribbean and Central America to Ecuador, Columbia and Brazil in South America.
Republicans in Congress blocked 1.6 billion dollars in funding to fight Aedes mosquitoes and Zika and the White House announced that they would redirect $589 million in funds for Zika from existing Ebola funding.
The CDC says the data from their studies in Latin America should be analyzed by May 2016.
UPDATE April 10, 2016 – The CDC has changed it’s recommendation for pregnant women from “consider postponing” to “should not travel.”
“Zika virus can be spread from a pregnant woman to her fetus and has been linked to a serious birth defect of the brain called microcephaly in babies of mothers who had Zika virus while pregnant. Other problems have been detected among fetuses and infants infected with Zika virus before birth, such as absent or poorly developed brain structures, defects of the eye, hearing deficits, and impaired growth. CDC recommends special precautions for pregnant women. Women who are pregnant should not travel to areas with Zika. If you must travel to one of these areas, talk to your healthcare provider first and strictly follow steps to prevent mosquito bites during your trip.”
UPDATE March 25, 2016 – A baby in Panama is thought to be the first detected outside of Brazil with microcephaly and traces of zika “in the baby’s umbilical cord.” There was no evidence that Zika was present 7-9 months earlier in the first trimester when it’s theorized the virus might impact brain development and no evidence that Zika caused the microcephaly.
UPDATE March 15, 2016 – A retrospective statistical analysis in the British Medical journal the Lancet may have found 8 cases in the Polynesian outbreak of 2013
UPDATE February 28, 2016 – In a press release the U.S. government stated “As spring and summer approach, bringing with them larger and more active mosquito populations, we must be fully prepared to mitigate and quickly address local transmission within the continental U.S., particularly in the Southern United States.” Millions of dollars are being spent to eliminate mosquitoes and prepare the health system for the inevitable increase in U.S. cases. As of February 2016 two cases of sexual transmission had been detected in the U.S. The first was in 2008 and the second in Dallas Texas in 2016. There have also been more than 50 recent imported cases in the U.S. (caught zika in Brazil or elsewhere and got sick after returning home).