HUMAN & ANIMAL HEALTH
Chagas Disease, Fever Tick, Chronic Wasting Disease and Zika Virus currently comprise Human and Animal Health
It is the triatomine bug, most commonly known as the “kissing bug”, which can cause Chagas disease. Mature, the kissing bug (so-called because most bites occur around the lips) can be as long as eight inches and is found in the Americas, Africa, Asia and Australia. When an infected bug bites and feeds off a person, it most often defecates around the wound. If a person scratches the area, it is then that the disease is transmitted to the person.
Chagas disease first causes a localized reaction. Later on, the parasite can affect the digestive tract and heart; and, can ultimately cause death. Sudden death has also been said to occur. Currently there are no vaccines and the few medications that exist are not always beneficial. Over 300,000 Americans, mostly Texans, are infected with the disease.
When a canine carries the Chagas parasite it is also normal for the heart to become compromised. The symptoms are somewhat different in dogs, however. Their symptoms are coughing, abdominal swelling and fainting during physical exertion. Landowners in South Texas who have hunting dogs and family pets have witnessed these debilitating effects that have ultimately led to the death of their dogs.
In the past, little investigation had been conducted on Chagas disease. In fact, it was considered a “neglected tropical disease” according to Dr. Peter Hotez, Dean of the National School of Tropical Medicine at Baylor College of Medicine. However, in the past couple of years, more attention has been drawn to the issue which has resulted in the first FDA-approved treatment for Chagas disease, benznidazole tablets. The drug company Exeltis has officially launched the sale of benznidazole in the United States for the treatment of Chagas disease. This means that physicians in the U.S. will no longer need to go through the CDC to access the drug for treatment and it will no longer be available through the CDC. The drug will be available through the Exeltis website. Benznidazole tablets, a nitroimidazole antimicrobial, is indicated in pediatric patients two to 12 years of age for the treatment of Chagas disease. However, prescriptions can still be filled “off-label” for other age groups. A patient assistance program is available, including free medication for uninsured or low-income patients (info on the website), or low-cost ($60 or less) pricing for patients whose insurance does not provide coverage. There is currently not a vaccine for Chagas disease.
STPRA has taken on this issue in order to educate its members and general public about the possible effects of Chagas disease. STPRA will continue to provide current findings, evidence, and information to our members and others that will in the end help with the optimum outcome: development of a therapeutic vaccine for humans and dogs.
As a result of a Chagas Disease seminar that STPRA co-sponsored with Caesar Kleberg Wildlife Research Institute (CKWRI) in May of 2014, Paula Stigler-Granados, an assistant professor at the School of Public Health in San Antonio, was inspired to apply for and was eventually awarded a five-year, $544,329 grant from the Centers for Disease Control and Prevention (CDC) to conduct outreach and education on Chagas disease in South Texas. This activity in turn has led to the Texas Chagas Task Force, of which STPRA is a member, and the new Kissing Bug & Chagas Disease Guide.
Berdon Lawrence, STPRA Issues Chairman, who brought this issue to the attention of the STPRA board, stated: “We owe it to our over 500 members and the general public to educate them about the disease.”
As the aforementioned information suggests, the lack of complete data of the disease is a catalyst to continue to gather information in order to keep our members informed of this potentially debilitating and rare disease.
STPRA will continue to work with stakeholders, which include veterinarians, doctors and researchers, and will host informational meetings to continue to bring awareness to many in South Texas. We also plan to have the Kissing Bug & Chagas Disease Guide professionally printed and disseminate them to our members and the public.
In 1893, the Texas legislature created the Livestock Sanitary Commission (now the Texas Animal Health Commission) with the mission of wiping out the fever tick. At the time, cattle fever ticks were endemic in the South, Southeast and in Southern California. By 1943, combined state and federal efforts pushed them back to the Mexican border in Texas. Since then, USDA's efforts have concentrated on keeping the tick contained within the permanent quarantine zone.
In the summer of 2007, it was discovered that the ticks had spread beyond the permanent quarantine zone, which is a narrow strip of land running for 500 miles along the U.S. Mexican border from Cameron to Val Verde Counties. As a result of this discovery, temporary quarantine zones were quickly added. Boundaries of the temporary zones have been adjusted several times since 2007, but maps of the current temporary zones can be found at http://www.tahc.state.tx.us/. Cattle from the permanent and temporary quarantine zones must be individually inspected and dipped before being allowed to leave the zones. There have been debates about how to most effectively combat the spread of fever ticks, but that task became harder with the 82nd legislature’s de-funding of fever tick operations by the Texas Animal Commission.
STPRA has been very active in advocating for more funding and solutions for fever tick eradication. In December of 2007 and the summer of 2008, STPRA sponsored large gatherings of ranchers, interest groups, and government officials in the Rio Grande Valley to discuss the fever tick issue and design remedies. STPRA board members and the executive director have also been very active in attending other meetings and working group sessions on fever ticks. Our organization has communicated diligently with state and federal agencies to seek their involvement and cooperation. We have asked the Food and Drug Administration to speed up research and approvals of vaccinations and treatment drugs. The membership has been kept informed on the issue through updates and presentations at member meetings. We have testified before legislative committees and have actively pursued additional funding at both the state and federal levels.
Partially as a result of STPRA’s efforts, some progress has been made in securing additional resources for fighting fever ticks. In 2008, the USDA dedicated about $5 million from an emergency fund to be applied toward fever tick eradication. In 2009, Congressman Henry Cuellar was successful in gaining approval of an increase in annual appropriations from about $9 million to about $20 million. Also in 2009, the Texas legislature increased appropriations by about $1 million, with an additional $500,000 for game fencing because wildlife often spread the ticks. Unfortunately, state funding was cut completely in 2011.
STPRA supports the provision of all necessary state and federal resources to control fever ticks and protect private property, including livestock, deer and exotic game. We also support the effective use of ivermectin treated molasses feed tubs for the control of fever ticks in cattle and ivermectin treated corn for the control of the fever tick in deer and the current development of a therapeutic vaccine for fever tick in cattle that is scheduled to be released this Fall.
The battle with fever ticks is far from over. Waging it has gotten increasingly complex and difficult as border violence has grown. STPRA will continue to be a loud, clear voice, both independently and with our allied organizations, advocating new effective approaches for controlling fever ticks and adequate funding to implement them. STPRA is committed to doing our part to protect the livelihoods of property owners who are threatened by a failure to eradicate fever ticks.
CHRONIC WASTING DISEASE
Chronic Wasting Disease (CWD) is a neurological disease in deer, elk, moose and other members of the deer family, known as "cervids." The disease was first recognized in 1967 in captive mule deer in Colorado, and has since been documented in captive and free-ranging deer in 21 states and two Canadian Provinces. CWD among cervids is a progressive, fatal disease that commonly results in altered behavior as a result of microscopic changes made to the brain of affected animals. An animal may carry the disease for years without outward indication, but in the latter stages, signs may include listlessness, lowering of the head, weight loss, repetitive walking in set patterns, and a lack of responsiveness.
CWD cases in captive deer have been discovered in South Texas counties. These discoveries are being addressed by the Texas Parks and Wildlife Department (TPWD) and the Texas Animal Health (Commission in accordance with their joint CWD Management Plan. The plan was developed by the state’s CWD Task Force composed of deer and elk breeders, wildlife advocates and biologists, veterinarians and other animal-health experts from TPWD, TAHC, the Department of State Health Services, the Texas A&M College of Veterinary Medicine, and the U.S. Department of Agriculture.
STPRA has been an active supporter of state and federal agencies that have been involved in ongoing efforts to stop the spread of CWD. We have testified at rule-making hearings, emphasizing the importance of controlling the disease to the economic viability of many millions of privately owned land throughout the state. We have also supported legislation to better regulate the deer breeding industry and stem the spread of CWD.
STPRA will continue to be vigilant in monitoring reported CWD outbreaks. We will also continue to support administrative and legislative action to prevent further damage by the disease, while maintaining a reasonable amount of private property regulation.
The Zika virus was first discovered in 1947 and is named after the Zika Forest in Uganda. It is spread by daytime-active Aedes mosquitoes, such as A. aegypti and A. albopictus. Zika virus is related to the dengue, yellow fever, Japanese encephalitis, and West Nile viruses. Since the 1950s, it has been known to occur within a narrow equatorial belt from Africa to Asia. From 2007 to 2016, the virus spread eastward, across the Pacific Ocean to the Americas, leading to the 2015–16 Zika virus epidemic.
The potential societal risk of Zika is determined by the distribution of the mosquito species that transmit it and human-to-human transmission. The global distribution of the most cited carrier of Zika, A. aegypti, is expanding due to global trade and travel. A. aegypti distribution is now the most extensive ever recorded – across all continents including North America and even the European periphery (Madeira, the Netherlands, and the northeastern Black Sea coast). A mosquito population capable of carrying Zika has been found in a Capitol Hill neighborhood of Washington, DC, and genetic evidence suggests they survived at least four consecutive winters in the region. A study indicates that mosquitoes are adapting for persistence in a northern climate. The Zika virus appears to be contagious via mosquitoes for around a week after infection. The virus is thought to be infectious for a longer period of time after infection (at least 2 weeks) when transmitted via semen.
Research into ecological factors suggests that Zika may be influenced to a greater degree by changes in precipitation and temperature than dengue, making it more likely to be confined to tropical areas. However, rising global temperatures would allow for the disease vector to expand their range further north, allowing Zika to follow. The U. S. Center for Disease Control (CDC) identifies Texas, particularly South Texas, and Florida as the current areas most likely to host Zika in the United States.
Zika virus is linked to the birth defect microcephaly, a condition where a baby's head is much smaller than expected and can cause developmental delays. The virus is also known to cause other poor birth outcomes in some women infected during their pregnancy. The CDC recommends that pregnant women should not travel to areas with Zika virus infection risk. The CDC also recommends that all pregnant women who have a sex partner who has traveled to or resides in an area with Zika use barrier methods every time they have sex or they should not have sex during the pregnancy.
STPRA is limited in our ability to help prevent the spread of the Zika virus since the virus has the potential to widely affect geographic areas that include those of intensive urbanization. Nevertheless, because South Texas is a prime location for the spread of the disease, we are dedicated to doing our part in informing our members and the general public of prevention methods, which, besides avoiding sexual transmission and travel to infested countries, mainly include general mosquito control methods:
- At least weekly empty or get rid of cans, buckets, old tires, pots, plant saucers and other containers that hold water.
- Keep gutters clear of debris and standing water.
- Remove standing water around structures and from flat roofs.
- Change water in pet dishes daily.
- Rinse and scrub vases and other indoor water containers weekly.
- Change water in wading pools and bird baths several times a week.
- Maintain backyard pools or hot tubs.
- Cover trash containers.
- Water lawns and gardens carefully so water does not stand for several days.
- Screen rain barrels and openings to water tanks or cisterns.
- Treat front and back door areas of homes with residual insecticides if mosquitoes are abundant nearby.
- If mosquito problems persist, consider pesticide applications for vegetation around the home.
We also favor research into vaccinations that would prevent the effects and transmission of the disease.
We will continue to monitor the spread of the disease in South Texas, to provide information to avoid its spread, and to support the development of vaccinations that prevent the effects and transmission of the disease.