Amblyomma americanum has been removed from patients 

 with the characteristic skin lesions of Lyme disease. Also, the 

 spirochete of Lyme disease has been isolated from both A. 

 americanum and D. variabilis. If these two ticks are found to 

 be efficient transmitters of the agent of Lyme disease, then the 

 potential geographical distribution of the disease will be 

 greatly extended. 



Animal and Plant Health Inspection Service personnel 

 working in situations where they are exposed to ticks should 

 be alert to the signs and symptoms of this recently 

 recognized disease. In humans, Lyme disease is 

 characterized by a skin lesion (erythema chronicum migrans) 

 that may be accompanied by headache, stiff neck, fever, 

 malaise, fatigue, aching muscles and joints, and swollen 

 lymph nodes. Weeks or months later some patients develop 

 brain and heart infections, central and peripheral nervous 

 disorders, and migratory musculoskeletal pain. Still later 

 arthritis may develop and persist for several years resulting in 

 erosion of cartilage and bone. Persons experiencing fever 

 and symptoms following exposure to tick bites should 

 immediately consult a physician. Lyme disease, like Rocky 

 Mountain spotted fever, should be diagnosed and treated by 

 a physician. 



Heartwater Menace Increasing 



Heartwater is a rickettsial disease of ruminants spread by 

 several species of ticks of the genus Amblyomma. 

 Traditionally a plague of domestic and wild ruminants in 

 Africa, heartwater organisms and African bont ticks 

 (Amblyomma variegatum) have been introduced to the 

 Caribbean islands of Antigua, Guadeloupe, and Marie 

 Galante. To make matters worse, the African tick has been 

 spread to over a dozen additional Caribbean islands. These 

 events pose an extremely serious threat to domestic and wild 

 ruminants of the United States. Heartwater can produce 

 mortality rates exceeding 50 percent in domestic cattle and 

 sheep, and there is no effective vaccine or treatment. 

 Experimental infections at the USDA's Plum Island Animal 

 Disease Center have demonstrated heartwater to be highly 

 lethal for white-tailed deer. If heartwater-infected animals or 

 ticks are introduced into the southern United States, it will 

 result in a foreign animal disease emergency with almost 

 certain involvement of white-tailed deer. Deer losses due to 

 this awesome pathogen could devastate this big game 

 resource. Furthermore, deer that survive infection may have 

 to be slaughtered as disease carriers. In addition to the 

 African bont tick, the gulf coast tick (Amblyomma maculatum) 

 that is often found on deer in the Southeast has been shown 

 to be capable of transmitting heartwater. Real trouble could 

 be on the horizon unless action is taken soon. A plan is being 

 formulated for bont tick eradication on the affected islands in 

 the West Indies. As proposed during a recent meeting of the 

 Secretary of Agriculture's Advisory Committee on Foreign 

 Animal and Poultry Diseases, the program v/ould be 



administrated by the Agency for International Development 

 and provide economic benefits to the island dwellers as well 

 as protection for the United States. With big game resources 

 very much at risk, wildlife conservationists would be wise to 

 actively support this disease eradication effort while the 

 problem is still contained on small islands without deer. 

 (Southeastern Cooperative Wildlife Diseases Study, College 

 of Veterinary Medicine, University of Georgia, Athens, 

 Georgia, 30602.) 



1985 Research Highlights — Cattle Fever Tick Research 

 Laboratory, USDA, Agricultural Research Service 



In 1982 a population of Boophilus microplus in the State of 

 Vera Cruz, Mexico, was reported to be resistant to 

 coumaphos and other organophosphate acaricides. By 

 December of 1984 the distribution of resistant B. microplus 

 was known to include the northern one-half of Vera Cruz and 

 the contiguous areas of the adjacent states of Tamalipas, San 

 Luis Potosi, Hidalgo, and Puebla. Concern within the United 

 States about the introduction of acaricide resistant ticks into 

 Texas, prompted efforts to obtain samples of resistant ticks. 

 Research entomologists at the USDA, ARS, Cattle Fever Tick 

 Research Laboratory, Mission, Texas, conducted studies to 

 characterize the spectrum of resistance to acaricides 

 available to the Tick Eradication Program and to test new 

 compounds as alternatives. Two strains of acaricide resistant 

 ticks from Mexico are discussed below. 



During July of 1984, through the joint efforts of Veterinary 

 Services and Agricultural Research Service, collections of S. 

 microplus, the tropical cattle tick, were made from several 

 locations in southern Mexico. Preliminary bioassays to 

 evaluate susceptibility to organophosphate (OP) acaricides 

 suggested that ticks in samples from several locations 

 behaved abnormally. The so-called "Tuxtla"strain was 

 designated for selection experiments to determine if the 

 frequency of the genetic factor for resistance could be 

 increased. At the Cattle Fever Tick Research Laboratory, 

 Mission, Texas, the Tuxtia strain has been subjected to 

 pressure through ten generations to select for a 

 homogeneous OP resistant strain. The Tuxtia strain in colony 

 at the Mission Laboratory is at present, approximately 20 

 times more resistant to coumaphos than normally susceptible 

 strains of B. microplus. Once laboratory studies indicate the 

 colony has achieved a sufficiently high level of homogeneity 

 of resistance factor and that point is near, efforts will be made 

 to characterize the degree of resistance of the ticks to a 

 variety of acaricides. This will enable laboratory personnel to 

 determine the degree of protection that can be obtained with 

 presently available chemicals or possible substitutes. 



In December 1984, scientists from the National 

 Parasitological Laboratory in Cuernavaca, Mexico, provided 

 the Cattle Fever Tick Research Laboratory, Mission, Texas, 

 with engorged females and eggs of the "Tuxpan" strain, the 



