Natural human infections with Vaccinia virus during bovine vaccinia outbreaks
Received 12 July 2008; received in revised form 7 December 2008; accepted 14 January 2009. published online 26 February 2009.
Abstract
Background
Bovine vaccinia is an exanthematic disease caused by Vaccinia virus (VACV). This zoonosis has been associated with several cases of bovine infection, particularly in milk herds. Farmers, milkers and their close contacts developed lesions on the hands, forearms, legs and face accompanied by fever, headache, malaise, myalgia and axillary, inguinal and cervical lymphadenopathy. VACV infections have a significant public health impact due to their occupational character, high frequency of transmission and the improper medical treatment often applied.
Objectives
To study natural human infection by VACV and to analyze clinical and epidemiological aspects, emphasizing the patients’ immunological status.
Study design
Ninety-eight individuals from rural properties with bovine vaccinia (BV) outbreaks who were at risk due to contact were submitted to epidemiological and clinical studies. From these individuals, 54 sera were analyzed by serological and molecular procedures. This study was conducted in Rio de Janeiro State from September 2002 to October 2006.
Results
The clinical frequency of infection was 52.0%, with 57.4% ELISA and 43.0% PRNT-positive reactions. DNAemia was detected in 18.5% of the analyzed sera, and 50% of smallpox-vaccinated individuals developed symptoms.
Conclusions
This study confirms the high clinical frequency of human VACV infection, even among vaccinated individuals. The infection was related to detection of IgG- or IgM-specific antibodies that correlates in most of the cases with positive PRNT. The DNAemia suggests viremia during VACV natural infections. Our data indicate that patients vaccinated against smallpox may no longer be protected.
aLaboratório de Sanidade Animal, Hospital Veterinário, Centro de Ciências e Tecnologias Agropecuárias, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Av. Alberto Lamego, 2000, Campus Campos dos Goytacazes, CEP: 28015-620, Campos dos Goytacazes, Rio de Janeiro, Brazil
bLaboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Campus Pampulha, CEP: 31270-901, Belo Horizonte, Minas Gerais, Brazil
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