Slideshow: Cases Involving Animal Exposure, Part 2

This is part 2 of a 2-part series on cases involving animal exposure.

Part 1 can be found here.

Click through the slides to view cases involving exposure to various animals. Each slide links to the full case report for more details.

A previously healthy 38-year-old farmer presented to the emergency department (ED) with a lesion on his left thumb. Upon questioning about his exposure history, the patient noted that the lesion had developed in the wound bed where his daughter’s sheep had recently bitten him. The patient added that the sheep had had a scab around his mouth.

Orf virus is a zoonotic member of the genus Parapoxvirus. Parapoxviruses are found worldwide and are common pathogens in small ruminants such as sheep and goats. Parapoxvirus infection in sheep and goats may be referred to as sore mouth, scabby mouth, contagious pustular dermatitis, contagious ecthyma, or orf, and the corresponding human infection is referred to as orf.

After 3 to 5 days of incubation, lesions begin as erythematous macules and then raise to form papules (days 7-14), sometimes with a targetoid appearance. Lesions become nodular or vesicular and often ulcerate after 14 to 21 days. Complete healing can take 4 to 6 weeks

Read the full case report here.

Murine typhus, also called endemic typhus or flea-borne typhus, is a zoonotic bacterial illness caused by Rickettsia typhi and Rickettsia felis. The vectors of R typhi and R felis are fleas, and the reservoirs are rats, cats, dogs, humans, and opossums. The bacteria can spread to humans when infected flea feces get into an open wound or are inhaled. Common symptoms manifesting 7 to 14 days after R typhi infection are fever, myalgias, arthralgias, headache, and rash. In many patients, the rash is diffuse and maculopapular, starts at the trunk, spreads to the extremities, and spares the palms and soles of the feet. In the United States, cases are concentrated in warm, coastal suburban areas, and the major route of infection involves opossums and cats. Less than 100 cases are reported each year in the United States, but the cases are endemic to California, Hawaii, and Texas.

Read the full case report here.

This patient sustained bites from fire ants, which are indigenous to the US Southeast, including Florida, to where he had recently traveled. The bites, which are painful, within 24 hours will produce sterile pustules that can be tender, pruritic, or both. Treatment is symptomatic. Some patients may develop systemic symptoms. The best treatment is prevention by wearing appropriate footwear in endemic regions and being aware of one’s surroundings.

Read the full case report here.

Lyme disease, the most common tick-borne disease in the United States, is caused by the spirochete Borrelia burgdorferi sensu stricto. It is transmitted by the infected blacklegged deer tick: Ixodes scapularis in the east and upper midwest (especially Minnesota, Wisconsin, and northern Illinois), and Ixodes pacificus in the west. The disease is initially recognized by clinical symptoms and signs occurring in patients from an endemic area. The incubation period is 1 to 32 days (median 11 days) from tick bite to the appearance of a single or multiple cutaneous lesions.

Read the full case report here.

Lyme disease is a very common cause of erythema migrans (EM). Lyme disease is caused by spirochete B burgdorferi and is transmitted by Ixodes ticks. Rodents such as the white-footed mouse are the primary reservoirs of Borrelia spirochete species.

During the initial days after tick exposure, Lyme disease can present with nonspecific signs and symptoms resembling a viral syndrome, such as fatigue, anorexia, headache, myalgia, and fever. These manifestations can occur up to 30 days after a tick bite. Upper respiratory and gastrointestinal signs and symptoms are uncommon in Lyme disease.

Read the full case report here.

Chiggers, commonly known as red bugs or harvest mites, are tiny 6-legged juvenile mites in the Trombiculidae family that bite in the larvae stage. Chiggers are red in color but are barely visible to the naked eye. Although they do not burrow into the skin, salivary proteins deposited at the site of the bite can induce intensely pruritic, erythematous papules measuring from 1 to 10 mm in diameter.

Read the full case report here.

In the United States, 99% of snake envenomation cases are from members of the Crotalinae (pit viper; formerly Crotalidae) subfamily of the Viperidae (viper) family, which includes copperheads, rattlesnakes, and cottonmouths (water moccasins). The risk of significant morbidity and mortality is higher in children than in adults because of their smaller body size in relation to the dose of venom.

Read the full case report here.

S. moniliformis, the primary causative agent of RBF in the United States, is a rare zoonotic disease, both in New York State and nationally. Nationally, over 200 cases have been documented; however, since RBF is not a nationally notifiable disease, this number is likely a great underestimate of the true case count.

Transmission of S. moniliformis occurs by direct contact through a bite or scratch from an infected rat or from exposure to their oral secretions or food/water contaminated with rat waste products. Less commonly, the disease can be transmitted by other rodents (eg, mice, gerbils, or squirrels) or rodent-eating animals (eg, weasels, cats, and dogs). Symptom onset usually occurs within 3-10 days of exposure, but can take up to 3 weeks. They include the sudden onset of chills, fever, headache, muscle pain, and vomiting. Typically, within a few days after fever onset, a maculopapular rash develops over the extremities.

Read the full case report here.

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