Updates
By Carol A. Kemper, MD, FACP, Clinical Associate Professor of Medicine, Stanford University, Division of Infectious Diseases; Santa Clara Valley Medical Center, Section Editor, Updates; Section Editor, HIV, is Associate Editor for Infectious Disease Alert.
Treating Chronic HEV with Interferon-α
Source: Kamar N et al. Pegylated interferon-a for treating chronic hepatitis E virus infection after liver transplantation. Clin Infect Dis. 2010;50:e30-e33.
As recently discussed in Infectious Disease Alert (January 2010), chronic Hepatitis E virus (HEV) infection has been described in solid-organ transplant recipients, and uncommonly in persons with HIV. This report describes three solid-organ transplant recipients with chronic HEV infection treated with 12 weeks of pegylated interferon-α.
All three patients had received cadaveric liver transplants, the first two for chronic HBV infection, and the third for sclerosing cholangitis. The first patient developed acute hepatitis at 130 weeks post-transplantation. Liver biopsies showed acute hepatitis not consistent with rejection, and studies for HBV were negative. However, blood and stools were positive for HEV RNA. His immunosuppressive therapy was decreased, but nearly a year later, he continued to have abnormal transaminases, progressive disease on liver biopsy, and persistently positive HEV RNA test results. He received Peg-IFN-α at 135 micrograms/week for 12 weeks. Within one week, his liver enzymes improved, and serum HEV RNA levels became undetectable, and remained undetectable six months later.
The second patient also had a cadaveric liver transplant for chronic HBV. About 65 weeks post-transplantation, he developed acute hepatitis, with progressive liver disease on biopsy without evidence of rejection or recurrent HBV infection. Although serum and stool specimens were subsequently found to be positive for HEV RNA, these results, and the diagnosis, were not made for another three years. His immunosuppressive therapy was decreased, but his liver disease worsened. Nearly eight years after transplantation, studies for HEV were still positive, and it was elected to treat him with Peg-IFN-α. Within one week, RNA levels dropped nearly one log, and were undetectable by completion of 12 weeks of therapy. He remained free of any evidence of HEV five months later. The third patient had a similar story, and demonstrated good virologic suppression during Peg-IFN-α therapy, with negative serum HEV RNA at the end of 12 weeks of therapy, but unfortunately relapsed 15 days after completion of therapy.
These data suggest that pegylated-interferon therapy may be effective in chronic HEV infection in immunosuppressed persons. The first and third patient had hepatitis E genotype 3c, the most prevalent genotype identified in developing countries, while the second patient had genotype 3f. Further study is warranted to examine the optimal duration of therapy and safety in solid-organ recipients. Whether different HEV genotypes respond more favorably to treatment is not known.
Night of the Iguana?
Source:Promed-mail post, February 5, 2010; www.promedmail.org
Did you hear the one about dogs in southern Florida gnawing on dead iguana carcasses and developing possible botulism? Florida has had a bitter cold winter, and iguanas which are poikolotherms, and cannot store body heat are either freezing up and shutting down their metabolism, or dying. TV reports described cold, immobilized iguanas falling out of trees and residents telling tales of rotting carcasses on their lawns. Dogs apparently think they are large chew toys! One resident described how their dog was gnawing on a dead iguana one day, and developed progressive hindleg paralysis the next. At first, veterinarians were stumped when dogs began developing progressive paralysis and respiratory failure. Several dogs, whose owners could not afford intubation and critical care, have died. Botulism is the most likely diagnosis, pending laboratory confirmation.
Adventure Racers Get Too Wet and Wild
Source: Stern EJ, et al. Outbreak of Leptospirosis among adventure race participants in Florida, 2005. Clin Infect Dis. 2010;50: 843-849.
The United States Adventure Racing Association National Championships, which took place November 4-5, 2005, ended up wilder than expected. This endurance race, which took place over about 24 hours, covered a distance of more than 100 miles and involved paddling canoes, portaging, trekking, and orienteering, including portaging and swimming in the Hillsborough River and nearby creeks and swamps.
About 11 days after the event, a 32-year-old male participant developed fever, headache, and muscle aches, requiring hospitalization in New York. Although initial Leptospirosis antibody tests were negative, other racers began complaining on the net of similar symptoms, and one California racer tested positive for Leptospirosis.
Investigation revealed that 44 (23%) of 192 racers available for testing met the case definition for acute Leptospirosis, including fever plus two or more signs or symptoms of infection (e.g., headache, myalgia, eye pain, conjunctival suffusion, jaundice, dark urine, or unusual bleeding). Symptoms included fever (100%), headache (91%), chills (69%), sweats (68%), muscle or joint pain (68%), and eye pain or photophobia (39%). The mean incubation time to onset of symptoms was two weeks (2-32 days); three patients required hospitalization. Risk factors associated with infection included swallowing river or swamp water, being submerged in water, and eating wet food. Cuts on the legs and wearing shorts were not statistically significant in univariate analysis, but most of the racers had wicked cuts on the legs from tree stumps and sharp saw palmetto leaves.
Testing at the CDC discovered a unique serovar of Leptospirosis, L. noguchii, which has been found in rodents, possums, toads, dogs, and sheep in the southern United States. Environmental samples collected six weeks later failed to find evidence of Leptospirosis.
Two other adventure races, including a triathlon in Illinois in 1998 and the 2000 Borneo Eco-Challenge, resulted in outbreaks of Leptospirosis in participants. Since many of these types of races include significant water exposure, event directors should consult specialists in advance regarding the risk of Leptospirosis, and the need for possible chemoprophylaxis or empiric post-exposure treatment.
New Money, Old Parasite
Every year about this time, I see a couple of unhappy local residents who present with an intensely pruritic, erythematous papular mystery rash. In contrast to flea bites, which are simple raised papules, the lesions seem umbilicated or have a central bite mark. The patient is typically floored when I explain they have rat mite bites, and they need to go home and set traps I mean, this is Palo Alto! It is estimated that half the homes in this area have resident roof rats, or Rattus norvegicus, especially at this time of year, when they are looking for a warm, dry place to nest. The spiny rat mite, Laelaps echidnina, is the most common ectoparasite found in large rodents.
Chiggers and mites are a frequent cause of dermatosis in patients referred to the ID clinic, especially in travelers,1 where the rash must be distinguished from those of sand flies and other parasites. Chiggers and non-human mites typically cause an intensely pruritic, red bumpy rash. Non-human mite dermatosis can result from animal or plant infestations, including animal habitats, dens, bird nests, fruits, trees, and furniture. Mites cannot jump, but they can crawl about 1 inch per hour on warm dry skin. Just like scabies, female mites burrow under the skin, where they lay their eggs. A sampler of different mites is as follows:
Chiggers are free-living ectoparasites, meaning the larvae feed for a few hours, and then drop to the ground, before maturing into nymphs (including the trombiculid chigger species Leptotrombidium, which can transmit scrub typhus). Chigger bites are initially painless but, within hours, become intensely pruritic, followed by an erythematous papular eruption, called prurigo, which lasts a day or two. The bites are commonly found in areas where clothing is tighter, such as around waistbands, underwear, thighs, and ankles.
Zoonotic (or non-human) scabies from any number of mammalian and bird species can infect humans, who are essentially dead-end hosts; the larvae never develop in humans, although symptomatic infection from mites burrowing under the skin may still respond to 5% pyrethrine or ivermectin. Common mites in this category include the poultry mite (seen in poultry handlers, typically on the hands); bird mites (in bird fanciers, breeders, and pet shop owners), various rodent mites, such as the rat mite and the common house mouse mite (the latter can transmit Rickettsialpox (R. akari), resulting in a typical eschar). Pigeon mites have been known to cause infestations in apartment buildings, where they roost outside of windows and one hospital experienced a nosocomial outbreak of pigeon mites in patients and nurses.2 Bird-mite bites are usually self-limited and can be managed with antihistamines and topical corticosteroids.
Plant mites are more unusual, but include the North American and European straw itch mites, which can cause infestations in caned furniture, straw baskets, and straw rugs; they are most typically seen after hay rides in the fall. A characteristic "comet tail" has been described, which is literally the track of the mite moving away from the bite site. Other Pyemotes (plant mites) relatives can occasionally cause outbreaks, such as a large outbreak of North American oak leaf gall mite in residents in Pittsburg, KS. Plant insect mites can also occur in back packers, campers, and resort-goers, especially during the summer months, when mites breed and feed.
In travelers, chigger and mite bites must be distinguished from sand flea bites, such as those from Tunga penetrans (found in sub-Saharan Africa and South America) and Tunga trimamillata (found in Ecuador and Peru), which infect both animals and man. The pregnant sand flea females burrow under the skin, causing inflammation and ulceration the legs and feet can become so swollen as to be painful to walk. A recent consult was just this a young woman who took a brief Easter jaunt to Machu Pichu and presented with severe tungiasis with dramatic lower extremity swelling and multiple small black eschars just above her sock line quite different from mite bites.
Patient never seem as excited or intrigued as I am when they present with one of these dermatoses, but at least they are relieved to have an answer, even it means going home and setting rat traps.
References
- Diaz JH. Mite-transmitted dermatoses and infectious diseases in returning travelers. J Travel Med. 2009;17:21-31.
- Bellander AP, et al. Nosocomial dermatitis caused by Dermanyssus gallinae. Infect Control Hosp Epidem. 2008;29:282-283.
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