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Study Helps Define the Geographical Distribution, Relative Abundance, and Prevalence of Infections in Monmouth County Ticks

Freehold Township, New Jersey, June 1, 2007 - The Freehold Area Health Department and the Monmouth County Mosquito Extermination Commission announced the results of several studies that examined the geographical distribution, relative abundance, and prevalence of infections in ticks collected from selected public lands in Monmouth County.  Tick-borne diseases continue to pose a significant public health threat in New Jersey.  Over 32,000 confirmed Lyme disease cases have been reported in New Jersey since 1978.  The blacklegged tick transmits the pathogens that causes Lyme disease and two other emerging tick-borne diseases--human babesiosis and human granulocytic anaplasmosis (HGA).  The lone star tick, which coexists with the blacklegged tick throughout much of central and southern New Jersey, has been implicated as the vector of human monocytic ehrlichioses (HME and EWE) and a Lyme disease-like illness known as southern tick-associated rash illness (STARI). 

Both blacklegged and lone star ticks were encountered at each of the surveyed properties, although the relative abundance varied considerably among the sites.  Overall, collections of adult blacklegged and lone star ticks were similar, while lone star nymphs were encountered 2.6 to 7.3 times more frequently than nymphal blacklegged ticks. 

Adult blacklegged ticks were shown to be infected with the pathogens that cause Lyme disease (31.9% -50.3%), HGA (6.1%), and human babesiosis (9.5%), and co-infected with the agents of Lyme disease/HGA (2.7%) and Lyme disease/human babesiosis (6.3%-7.2%).  Lone star ticks were infected with the pathogens that cause STARI (5.8%-9.1%), HME (12.3%), and EWE (8.2%), and co-infected with STARI/HME (0.8%) and HME/EWE (4.1%). 

The results of these studies demonstrated that blacklegged and lone star ticks are abundant throughout much of suburban and rural Monmouth County and that these ticks are variously infected or co-infected with several tick-borne pathogens.  The simultaneous infection with 2 or more of tick-borne pathogens may complicate the diagnosis and treatment of Lyme disease, lead to more severe clinical progression of any of the diseases alone, and help explain the variable manifestations and clinical responses in some patients.  Co-infection of a substantial portion of ticks also argues for an integrated management strategy designed to significantly suppress vector tick populations.  Public health agencies should redouble efforts to inform the medical community and public of the potential exposure to multiple tick-transmitted pathogens throughout much of New Jersey.