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.
Fatal Plague in the US
CDC. MMWR Morb Mortal Wkly Rep. 2006;55:940.
Each year in the United States, a few isolated cases of plague are reported. This year, possibly because of increased spring rains leading to an increase in the rodent population, an unprecedented 13 cases of plagues have occurred in 4 states (New Mexico, California, Colorado, and Texas). Importantly, 5 (38%) patients had primary septicemic plague and, therefore, lacked an obvious tell-tale buboe. The remaining 8 (62%) patients had bubonic plague, 2 of whom developed secondary pneumonia. Two patients (15%) died.
Most human infection is acquired through the handling of infected animals (eg, domestic cats, rabbit and hare carcasses, squirrels, chipmunks) and from the infected fleas of various rodents. Pneumonic plague is highly contagious, and any individual with suspected disease should be placed in respiratory isolation. Family members, close contacts, and exposed health care workers require post-exposure prophylaxis with doxycycline. Delays in recognition of infection lead to an increased risk of mortality, as occurred in this report. Septicemic and pneumonia plague is quickly fatal if not promptly treated, and bubonic plague is about 50% fatal if not recognized.
Possible sources of infection in the current MMWR report included rabbit carcasses from Lea County, New Mexico and from Kern County in northern California, and infected fleas from various rodents on the victims' properties. Dogs owned by 3 of the victims had serologic evidence of past infection with Y. pestis. In one case, a 28-year-old woman living in Los Angeles came in contact with the raw meat from the Kern County bunny, presumably brought home for cooking. She developed painful right axillary swelling, fever, and septic shock. Because she had not traveled outside of Los Angeles and had none of the usual risk factors for plague, plague was not suspected.
As an aside, human plague in the developing world is much more common than in the United States. An outbreak of suspected pneumonic plague in the Congo this year has resulted in more than 100 deaths, promulgated by working conditions in crowded and poorly ventilated mines, leading to increased human transmission.
Imported Chik Fever
Promed-mail post, September 29, 2006; www.promedmail.org
More than 300 cases of imported Chikungunya fever (perhaps not so fondly called Chik fever at IDSA this past week) have been reported in Europe, and a dozen cases have been reported in the United States, all occurring in immigrants and travelers from Asia and Africa this year. This is occurring against a backdrop of an ongoing epidemic in these countries, where more than 300,000 cases of Chik fever have been reported in the Islands of the Indian Ocean, and 240,000 cases in Mombasa, Kenya, Madagascar, and the Seychelles since 2004. This year, the outbreak has moved into the Southern provinces of India and affected an estimated 180,000 people in Andhra Pradesh, Karnataka, and Maharashtra.
It is of little wonder that cases are popping up in the United States and Europe. The CDC has issued an alert that clinicians should be prepared to recognize cases among travelers. Cases include American tourists who traveled to Somalia, Kenya, Zimbabwe, and Reunion, as well as residents of India traveling to the United States.
While many cases of Chik fever are asymptomatic, the infection can cause abrupt onset of fever, headache, arthralgias and arthritis (both large and small joints), myalgias, low back pain, and rash. Serious illness is rare, and documented fatalities have not been reported. The incubation period is 2 to 4 days, and typically last 3 to 7 days, although patients may experience malaise and joint pain for weeks to months. The initial infection may be difficult to distinguish from malaria and Dengue, although the Chik rash is typically more diffuse, whereas that of Dengue may be petechial.
Officials are concerned that Chik fever could spread to the Americas. The predominate mosquito vector in Asia is Aedes aegypti and, to a less degree, A. albopictus (the Asian Tiger mosquito), but other mosquitoes may be an effective host. Fortunately, this illness is associated with a short duration of viremia, with the peak of viremia occurring during the first one to 2 days of the illness, and quickly tapering off by the 5th day of illness. Thus, most humans are at low risk for infecting mosquitoes. In fact, in this report, infection in 3 of the 4 US cases likely occurred before arriving in the United States, and were diagnosed serologically because of persistent joint complaints, after the fact.
Diagnostic tests for Chik fever are not commercially available, but specimens can be sent to the CDC. Both acute and convalescent sera are needed for diagnosis, but virus isolation and PCR can also be attempted. There is no specific treatment for Chik fever other than antipyretics and non-steroidals. No vaccine is available, but infection is believed to confer life-long immunity.
Mono-Like Illness in Travelers
Bottieau E, et al. J Travel Med. 2006; 13,191-197.
I was recently asked to consult on a middle-aged woman returning home from a 2-week vacation in Cost Rica, with pharyngitis, fever, lymphadenopathy, and severe genital ulcerations. While the diagnosis of genital HSV-2 infection was fairly certain and ultimately confirmed, she continued to have prominent cervical, axillary, and inguinal lymphadenopathy, abnormal liver function tests, and fatigue for 4 to 8 weeks following her return. Investigation ruled out malaria, viral hepatitis, and HIV, and eventually she was found to have acute toxoplasmosis, probably from eating deer meat at a barbecue.
Features of mono-like illness in returning travelers are not uncommon, including fever, pharyngitis, lymphadenopathy, splenomegaly, abnormal liver function tests, and lymphocytosis. Of course, the usual infections, such as malaria, dengue, brucella, and viral hepatitis would be quickly ruled out in febrile travelers returning from the tropics, along with possibly leptospirosis, bartenellosis, and secondary syphilis. But how frequently is mono responsible for mono-like illness in returning travelers?
Bottieau and colleagues investigated the frequency of mono-like syndromes in travelers returning from Africa, Asia, or Central or South America. During a 5-year period, 72 of 1842 (4%) of travelers presenting to the Institute of Tropical Medicine in Antwerp were diagnosed with acute EBV, CMV, acute primary HIV, or toxoplasmosis. More than half (58%) of the patients had previously consulted another physician and alluded diagnosis, and 45% had been given empiric antibiotics or antimalarials, or both. Of the 72 cases, acute primary CMV was the most frequent finding, occurring in 50% of the patients, followed by toxoplasmosis (22%), and EBV (21%). Six of the patients were diagnosed with acute primary HIV infection (8%), including one with concurrent CMV infection.
The 4 diseases were clinically indistinguishable. Duration of fever > 7 days (> 39 C), lymphadenopathy, lymphocytosis > 40%, and elevated ALT were found to be independent risk factors for the presence of infection due to toxoplasma, EBV, CMV, or HIV in returning travelers. The true, positive rate was 87% when all 4 findings were present, and 47% if 3 of the 4 predictors were present. In patients with a similar constellation of symptoms, alternate diagnoses included viral hepatitis, rickettsial infection, malaria, and dengue.
All of the patients with mono-like illness in this report recovered, although 25% required hospitalization for ongoing fever and other complications, including one patient with acute toxoplasmosis who developed severe polymyositis. Protracted fever > 3 weeks was common, and 60% of the patients experienced fatigue lasting greater than 2 months. Serologies for EBV, CMV, and toxoplasmosis should be included in the evaluation of febrile travelers with mono-like illness. And, don't forget that HIV test!
More Infections in Travelers
ProMED-mail post, September 26, 2006; www.promedmail.org
I was recently asked to see a young Mormon man who had just returned form 2 years of spreading the faith in Peru, with fever, dehydration, abnormal liver function tests, and rash. Work-up included the usual studies for malaria, dengue, and viral hepatitis, and blood cultures yielded a non-typhoid salmonella species. However, his experience in the agricultural areas outside of Lima prompted consideration of another possibility. Peru is experiencing a resurgence of Bartenellosis bacilliformis, possibly related to climatic changes and increased numbers of sandflies, the vector for B. baccilliformis. Infections have been occurring even in unexpected areas within an hour or 2 of Lima, such as the Rio Grande valley, and even areas at sea level, such as Huaral and Ica, where the infection has never been seen. Thus far this year, more than 4200 cases have been registered with the Ministry of Health in Peru.
Typically, this illness is limited to the Andean valleys, 2000-4500 ft. above sea level, where the sandfly vector can safely go about its day at dusk, when the winds die down. The organism may cause an acute febrile illness, called Oroyo fever, which was responsible for 10,000 deaths during construction of the Oroyo railway a century ago. Patients who develop bacteremia are at later risk for developing cutaneous verugas (Veruga peruana). The discovery that these 2 illnesses were causally related is attributed to Daniel Carrion, a medical student in Lima, who sadly died as a result of self-experimentation when he inoculated a sample of verrucous material from a patient and died of Oroyo fever. Early recognition and treatment is effective at limiting mortality, and can prevent the later complications. Recognition of the disease dates back to the Incas, and children in these Andean villages are told not to go out at dusk, lest the "veruga monster" get them!
Each year in the United States, a few isolated cases of plague are reported. This year, possibly because of increased spring rains leading to an increase in the rodent population, an unprecedented 13 cases of plagues have occurred in 4 states (New Mexico, California, Colorado, and Texas).You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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