Ehrlichiae and ehrlichial diseases in china.

The various ticks collected from different areas of China were examined for the existence of ehrlichial agents by polymerase chain reaction (PCR) with genus- or species-specific primers designed on the basis of ehrlichial 16S rRNA genes and sequence analyses. In southern China, E. chaffeensis was detected in Amblyomma testudinarium ticks from infested cattle, Haemaphysalis yeni ticks from hare, and Ixodes ovatus ticks from Muntiacus reevesi. E. canis was identified in Rhipicephalus sanguineus ticks from dogs and Boophilus microplus ticks from goats. A new species of the genus Ehrlichia, closely related to E. chaffeensis, and Anaplasma marginale were found in B. microplus ticks from cattle in Tibet. In northern China, E. chaffeensis was detected in Dermacentor silvarum and I. persulcatus ticks; the granulocytic ehrlichial agents were detected in I. persulcatus ticks from an area where Lyme disease is endemic. Canine ehrlichiosis was found in southern China and E. canis and E. platys were identified in dogs; human ehrlichioses were demonstrated by amplifying the 16S rRNA genes of E. chaffeensis and granulocytic ehrlichial agents from patients' blood specimens. In comparison of 16S rRNA gene sequences, the sequences of E. chaffeensis, E. canis, and E. platys in China were found to be different from that in other countries at certain nucleotide positions. These results reveal that a variety of tick-borne ehrlichial agents and diseases exist in China, and the ehrlichial agents and their tick-vectors are same as or different from that in other countries at species or strain levels.

[Tropical animal and human rickettsial infections]. / Rickettsioses animales et humaines tropicales.

Advances in molecular biology have provided tools that have greatly clarified our knowledge of rickettsial diseases. Most rickettsias have been reclassified in the alpha subgroup of proteobacteria. Four groups of rickettsias have been identified: the spotted fever group, the typhus group, Ehrlichia, and Bartonella. Although still considered as a rickettsia, Coxiella burnetti, the agent causing Q fever, has been reclassified separately in the gamma subdivision of proteobacteria. Recognition of rickettsial disease is still based mainly on clinical manifestations (rash, eschar, and scratching sores). Little progress has been made in serologic testing. Indirect immunofluorescence is the most common technique. Diagnostic techniques based on molecular biology are currently available in only a small number of laboratories. Treatment with tetracyclines is indicated but prophylaxis through proper hygiene is the most effective approach.

Human ehrlichiosis: more trouble from ticks.

Human ehrlichiosis, whether monocytic or granulocytic, presents as a flulike illness that can be severe or even fatal. Diagnosis is often difficult and usually empiric: persistent fever and malaise, thrombocytopenia, leukopenia, elevated liver enzyme levels, and tick exposure are clues. In cases treated early with doxycycline, the prognosis is good.