Sunday, June 26, 2011

FLASHBACK: Case Studies of Cowpox Virus Transmission from Pet Rats to Humans in France (2009)

Cowpox Virus Transmission From Pet Rats to Humans in France

It is fairly uncommon to see human cases of cowpox infection. There are scattered cases, but usually the infected people are in contact with wild animals. However in 2009, there were four (4) documented human cases of cowpox virus infection in France connected with pet rats in a short period of time. The article points out the need for sufficient border security in connection with importation of exotic animals, because exotic rodents might potentially be contaminated with pathogens such as cowpox or other genetically modified viruses.

The above document has further analysis on the matter, but the actual cases from France are defined below.

The Cases

Case-patient 1 was an 18-year-old woman. She was scratched on the right arm by a pet rat while visiting a friend who had several domestic rats (Rattus norvegicus). One rat had been purchased at the end of December 2008 from a pet store. The rat became sick with sneezing, conjunctival hemorrhages, and epistaxis; it died 4 days after purchase. On January 4, 2009, the patient sought treatment at the emergency department of Compiegne Hospital. The lesion was excised and the patient was treated with amoxicillin-clavulanate. However, the wound did not heal. On January 11, ofloxacin was added to the treatment regimen. Eight days later, the patient was admitted to the hospital with a black necrotic scab on the internal surface of the right arm, regional lymphangitis, and axillar lymphadenopathies (Figure 1, panel A). After 3 weeks of unsuccessful antimicrobial drug treatment, she underwent surgery to remove the affected area. The outcome was favorable.

Case-patient 2 was a 17-year-old woman who had purchased a domestic rat at the end of December 2008. The rat died within 3 days of purchase and had respiratory symptoms identical to those of the rat that scratched case-patient 1. Six days after the rat died, an inflammatory cutaneous macular lesion appeared at the base of the patient’s neck, causing local pain and intense inflammatory reaction. The patient was admitted to the emergency department of Compiègne Hospital. Amoxicillin-clavulate was prescribed, but the necrotic scab continued to grow, and local pain increased along with fever (39°C) (Figure 1, panel B). Surgery was performed and the outcome was favorable.

Case-patient 3 was a 14-year-old girl. She was admitted to the emergency department of Compiègne Hospital on January 14, 2009. On January 3, she had purchased a rat from the same pet store as case-patient 1. Soon afterward, the rat began to cough and show signs of hemorrhagic lachrymal oozing; the rodent died on January 6. On January 13, the patient had maculopapular lesions on the upper right eyelid, on her left shoulder, and at the base of her neck. Due to her deteriorating condition, she was admitted to the emergency department on January 17 with rash characterized by erythema and edema, and painful regional lymphangitis and lymphadenopathy. Surgery was performed and the outcome was favorable.

Case-patient 4 was a 29-year-old woman who reported having been scratched by a rat on January 21, 2009. An inflammatory macule on her clavicle had progressed through papular, vesicular, and pustular stages; she also had fever and malaise. On January 14, she had purchased a domestic rat in the same store as the 3 previous case-patients. The rat had respiratory symptoms similar to the previously infected rats and died on January 21. The patient was admitted to Compiègne Hospital on January 30; examination showed a 20-mm black eschar with a crust, regional lymphangitis, and painful lymphadenopathies (Figure 1, panels C and D). Outcome was spontaneously favorable.

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