Typhus, a flea-borne infectious disease thought to be all but eradicated in the United States, appears to be on the rise in Texas, say tropical disease experts.
A recent study in the U.S. Centers for Disease Control and Prevention (CDC) journal Emerging Infectious Diseases tracked Texas typhus cases over a decade, revealing the number of diagnosed patients rose from 27 in 2003 to 222 in 2013. Geographically, it spread from nine to 41 counties, although the highest incidence of bacterial infection still remains in south Texas where typhus is more prevalent. Between 2003 and 2013, the state reported 1,762 cases.
Dr. Kristy Murray, an associate professor in pediatrics and assistant dean of the National School of Tropical Medicine at Baylor College of Medicine and Texas Children’s Hospital, conducted the study with colleagues and the Texas Department of State Health Services (DSHS). In a July CDC interview, she said researchers found 60 percent of people infected with typhus in Texas got hospitalized while four cases proved fatal during the tracked 10 year period. She added they discovered children ages 5-19 were at higher risk to contract the illness.
Because Texas mandates typhus reporting, researchers could quantify the uptick in cases, although Murray acknowledged they are “really not sure” as to why the flea-borne disease continues to increase statewide.
Texas cases mainly occur in the southern border region of the state from Nueces County southward to the Rio Grande Valley, according to DSHS. Infected cat or rat fleas, lice, and chiggers, also called mites, transmit “murine” or endemic typhus, the strand caused by Rickettsia typhi bacteria.
Most fleas defecate while biting humans, passing the rickettsial organism through fecal matter that enters the body either through the bite wound or when a person scratches the bite area. Typhus is sometimes difficult to diagnose because some symptoms resemble flu-like ailments such as headaches, chills, body aches, and a rash. Typhus responds well to antibiotics but delayed medical treatment may result in hospitalization.
“We can now add typhus to the growing list of tropical infections striking Texas,” said Dr. Peter Hotez, founding dean of the National School of Tropical Medicine at Baylor and Texas Children’s Hospital,” who spoke to the Houston Chronicle which folded later statewide typhus figures from 2014 to 2016 into their report. This accounted for 308 cases in 2014, 324 in 2015, and 364 in 2016.
“Chagas, dengue fever, Zika, chikungunya and now typhus – tropical diseases have become the new normal in south and southeast Texas,” added Hotez.
The August Emerging Infectious Diseases journal includes a study that examines typhus cases in south Texas over three years in two Hidalgo County hospitals along the Texas-Mexico border. Medical experts at the University of Texas Rio Grande Valley and Baylor College of Medicine identified 90 cases between July 1, 2013, and June 1, 2016. Thirty-six of the diagnosed patients were younger than 18-years-old. Twenty-five experienced complications like bronchiolitis, pneumonia, aseptic meningitis, and sepsis with shock, although this occurred more frequently in adult patients. Children likely had rashes and diarrhea.
This study pointed out murine typhus declined sharply in the U.S. once DDT spraying began in 1945 but stated “now it appears to be on the rise, especially in southern Texas and California.”
It called out cats and opossums that coexist in urban and suburban settings as “reservoirs for the organism” noting “rickettsial DNA in pools of fleas from opossums in Galveston” and a major outbreak in Austin “traced to contact with opossums.”
Interestingly, the researchers highlighted that the U.S. northeast and northwest are the natural habitats of the American opossum, suggesting “typhus may not be confined” to states considered endemic for outbreaks such as Texas and California.
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