Tick toxicosis in a dog bitten by Ornithodoros brasiliensis.

Ticks are hematophagous parasites of people and animals and are a public health hazard in several countries. They are vectors of infectious diseases; in addition, the bite of some ticks, mainly from the Ornithodoros genus, may lead to local lesions and systemic illness, referred to as tick toxicosis. In this report, we describe a dog bitten by Ornithodoros brasiliensis, popularly known as the mouro tick. The main clinical findings were disseminated skin rash, pruritus, mucosal hyperemia, lethargy, and fever. Laboratory abnormalities 48 hours after the bites occurred included mild nonregenerative anemia, eosinophilia, basophilia, increased serum creatine kinase activity, increased serum C-reactive protein concentration, and prolonged coagulation times. Tick-borne pathogens were not detected by PCR analysis or serologic testing, supporting the diagnosis of a noninfectious syndrome due to tick bite, compatible with tick toxicosis.

Effects produced by the feeding of larvae of Ornithodoros aff. puertoricensis (Acari: Argasidae) on laboratory mice.

The clinical picture produced by the feeding of larvae of Ornithodoros aff. puertoricensis on laboratory mice, was studied using different larval infestation protocols that included 30, 40 or 50 larvae per mouse and control uninfested groups. Clinical effects appeared around 72 h of larval feeding, having a first stage characterized by hyperaemia in both nasal and ocular mucosa, followed by respiratory symptoms (96-120 h) and nervous incoordination (120-144 h). No one mouse evidenced paralysis, and nervous symptoms were never observed in animals infested with only 30 larvae. High mortality (commonly up to 70%) was observed in mice with respiratory symptoms, while 100% of animals in the nervous phase died between 168 and 192 h after the beginning of larval feeding. When some infested mice were treated with a solution of Amitraz the larvae were killed and reversion of symptoms was observed. These effects are ascribed to the presence of a toxin in the saliva of the feeding larvae.

Biochemical perspectives on paralysis and other forms of toxicoses caused by ticks.

Tick toxicoses, of which paralysis is the most widespread and dominant form, are important elements of pathogenesis induced by ticks. Tick paralysis is the most widespread and dominant form of tick toxicoses. Non-paralytic forms of tick toxicoses do occur and evidence suggests that these forms of toxicoses are not evolutionary related. While functional significance has been suggested for tick toxins, the advantages for tick survival in general are not clear. This review considers the molecular nature of tick toxins, the possibility that tick toxins have originated more than once independently and whether these toxins could have unrecognized benign functions.

[Toxicoses of ticks (Acari: Ixodida)]. / Toksykozy kleszczowe (Acari: Ixodida).

Toxins have been shown to present in the salivary glands, whole body extracts, and eggs of ticks. They cause histological lesions in the skin, and in various organs of tick hosts. Among toxicoses, tick paralysis is of the greatest medical and veterinary importance. Toxins are secreted by cells "b" of acinus II in salivary glands during tick feeding.

[A review of the types of parasite-host relations in ixodid ticks]. / Obzor tipov parazitno-khoziainnykh otnoshenii iksodoidnykh kleshchei.

In the first type of mutual relationships the ixodid ticks expose an evident pathogenicity to vertebrate hosts (tick toxicoses) and in the second type the hosts expose a resistance on a base of organism immune system activisation in a response to blood sucking. In the third type of relationships an interaction between the ticks and hosts have a dynamic character (tolerability of host). The first type of relationships leading to a selective elimination of hosts according to our opinion means a comparatively youth of relationships. The third type represent ancient and long term relationships. The second type probably having been widely spread in a historical past occupies an intermediate position. Depending upon areal the ticks of the same type expose different degree of the pathogenicity. Even an acquired resistance of the host does exist in natural conditions, it is a transient phenomenon.