Bracing for Zika

Will Zika be the next mosquito-borne disease to capture headlines in 2016?  Or will it be the little disease that few (at least in the U.S.) have heard of?  That's the question being debated by public health officials this year.

Current (2015) worldwide range of zika virus. Central and South
American countries were first reported with the disease in
2015 (U.S. Centers for Disease Control).

For many years it seemed like new things happened relatively slowly in public health in Texas. In the mid-1980s entomologists reported the Asian tiger mosquito in Texas for the first time--a daytime-flying mosquito from Japan that is not shy about biting humans. Then in 2002 the first cases of west Nile virus hit our state.  Carried by the southern house mosquito, WNV affected a couple of hundred people or less each year. This was the case until the blazing hot summer of 2012 when over 1800 cases were reported, including 83 deaths. Health departments throughout the state are still reeling, in some ways, from the impact.

Now health officials are bracing for another mosquito-borne disease caused by Zika virus (abbreviated ZIKV by epidemiologists).  A cousin of west Nile virus and dengue fever, ZIKV has been thought of as a less severe form of these flavivirus.  Most people who get ZIKV show no, or very mild symptoms.  Others exhibit a rash, conjunctivitis (inflammation of the eye), and flu-like symptoms.  Most people do not get as sick with ZIKV as with dengue fever or chikungunya, and recover relatively quickly.

For this reason, since its discovery in 1947 until 2007, it was not on the radar of many public health experts. But in 2007 ZIKV cases started to spread throughout Micronesia French Polynesia, and eventually Easter Island. There it was thought to possibly be the cause of a twenty-fold increase in cases of Guillain-Barre syndrome--an autoimmune disease of the central nervous system that can be highly disabling, at least temporarily.

In 2015 the disease made its appearance in Brazil and has since spread to at least nine other member states of the Pan-American Health Organization (PAHO/WHO), and prompting that organization this month to issue an alert to all of member public health agencies.

So here's where things get a little scary.  Since the arrival of ZIKV to Brazil, the virus has been detected in babies born with a condition known as microcephaly.  Microcephaly is a relatively rare condition where the brain fails to develop normally. It may result in miscarriage or in babies being born with under-sized brains.  There is no cure for the condition.  The PAHO/WHO alert noted that the number of diagnosed cases of microcephaly has increased to 2700, a 10-fold increase, in Brazil this year.  Health officials there are worried that there might be a connection between this unprecedented increase in microcephaly and the arrival of ZIKV.  And last month, unusual nervous system birth defects were also reported in Polynesian mothers who tested positive for flavivirus antibodies.

Public health officials guess that these cases may result when a pregnant woman who is bitten by an infected mosquito contracts the virus.  The virus then infects the developing fetus, resulting in this serious condition.

So far there is no hard proof of a connection between ZIKV and microcephaly or Guillain-Barre syndrome, but medical researchers are rushing to learn more about the virus and its possible effects on human health.  According to one expert, quoted in the New York Times, it could be that the risk of microcephaly is increased among people who have previously contracted dengue fever or chikungunya, neither of which diseases are common to Texas or the U.S. If this hypothesis proves correct, the risks to the unborn in this country would likely be negligible.

Currently, ZIKV is thought to be transmitted by the yellow fever mosquito, Aedes aegypti.  This mosquito, along with its close relative, Aedes albopictus, the Asian tiger mosquito, are both very common throughout Texas and the southern U.S.  Unlike west Nile virus, which is primarily a disease of birds, ZIKV is solely a disease of primates.  To be spread among people, it must be picked up from another infected human.

Dengue and chikungunya are similar, human-only, viruses that have not been quick to spread in Texas or other U.S. locations.  This may be the result of lower rates of mosquito biting in the U.S., perhaps due to our more indoor lifestyles, or more common use of repellents.  Some experts argue that for similar reasons ZIKV is likely to be slow to establish in the U.S.  Nevertheless, Brazil shows that given the right conditions, this virus is capable of establishing itself very rapidly, with 85,000 known infections in its first year of spread.

A few U.S. cases of ZIKV have been reported in 2015, but all from travelers who contracted the virus elsewhere.  Mexico has also seen a few cases this year.  There are still no known cases of ZIKV, however, contracted within the U.S.

So be prepared to hear more about the zika virus this year.  It may turn out to be a big event, or it may not.  Even if we didn't need more reasons to dislike biting mosquitoes, now we have one more reminder of the importance of residential mosquito control, and putting on the insect repellent when venturing outdoors.  

Climate change and changing times add up to new challenge for PMPs

One of my favorite anecdotes is about the famous British architect Christopher Wren. According to Wikipedia, "Wren designed 55 of 87 London churches after the Great fire of London in 1666, including St Paul's Cathedral in 1710, as well as many secular buildings of note." The story goes that Wren approached a man who was working on one of the buildings he had designed. When asked what he was doing, the man replied, "I'm laying brick." Wren approached a second construction worker engaged in the same work and repeated his question. The second man looked up and smiled and said, "I'm building a cathedral."

Every so often I think it's important that we stop focusing so closely at what we do, and look at the larger meaning and impact of our life's work. What kind of business are you in? Is it a business to make money? Is it a job to kill bugs? Or is your business helping people to lead healthier, safer and more pleasant lives? You may be running a residential route, or servicing commercial clients, or making sure your employees remain productive, but if you are in the pest control business, your job is more than just controlling pests.

I was reminded of the importance of our profession thanks to a note this weekend from Steve Baker, of International Exterminators in Fort Worth. Steve send an article from the Wall Street Journal on the increasing frequency of new diseases being seen, especially along the southern border with Mexico. Much of this has to do with changes in immigration patterns, but some of the concerns focus on spread of new pests into the U.S. Although data is still scarce, some people believe that climate change may be encouraging the spread of insect vectors of disease further north. In a response to a letter about a recent article on the impact of climate change on insects, University of California entomologist John Trumble notes that the ranges of more efficient vectors of this disease may be spreading north, even as the parasites follow immigrants across the border.

In Texas a major concern of health officials is the spreading incidence of the mosquito-borne disease, dengue fever. Warmer temperatures and increases in dense, low-income housing favor the spread of this disease. Caribbean (Rasberry) crazy ants, fire ants, argentine ants, and numerous plant-feeding insects are all likely to be favored by current trends in climate change.

Of course all this adds up to the growing need for pest control. How about if today, when you wonder if it's all worth it, you think about the bigger picture? You and your employees are not just killing bugs, you keeping your friends, neighbors and customers safe and healthy. Having people take a pest-free home or pest-free business for granted is a sign that you are doing your job well.

Christopher Wren would be proud.