Enterovirus detection as a result of West Nile virus surveillance.

In this 2005 study from the Los Angeles County Public Health Department Laboratory, Los Angeles, CA, cerebrospinal fluid specimens submitted for West Nile virus (WNV) serologic testing were also tested for enterovirus by real time reverse transcription-polymerase chain reaction and culture. Approximately 10% of the WNV- specimens were positive for enterovirus. Altered consciousness and muscle weakness were more common with WNV infection. Results provide compelling evidence that laboratory testing is a necessary adjunct to clinical diagnosis for accurate discrimination among the various possible etiologic agents of febrile and central nervous system disease.

West Nile virus infection in the pediatric population.

In 2004, Los Angeles County confirmed 11 cases of symptomatic West Nile virus (WNV) infections in children younger than 18 years of age. Eight had WNV fever, 2 had meningitis and 1 had encephalitis. Fever, rash, nausea and vomiting were the most prominent symptoms at presentation; median duration of illness was 7 days. Clinicians should be aware of the risk of WNV illness, confirm this diagnosis and report suspected WNV cases to their local health department.

Botulism due to Clostridium baratii type F toxin.

Botulism results from consumption of preformed toxin or in vivo toxin elaboration in wounds or intestine. Of U.S. food-borne botulism cases since 1950, the majority were due to toxin A, but a significant number of suspect cases were never confirmed by culture or toxin detection. We report here a possible case of food-borne botulism attributed to toxin F production by a Clostridium baratii organism isolated from food consumed by the patient. The isolation of a toxin-producing Clostridium species other than Clostridium botulinum from food and stool requires deviation from the usual laboratory protocols, which may account for the lack of complete laboratory confirmation of clinically diagnosed cases.

Campylobacter upsaliensis: Another pathogen for consideration in the United States.

While evaluating quinolone resistance in a sample of Campylobacter isolates recovered from patients with campylobacteriosis in Los Angeles County, California, in 1998, we discovered that the second most frequently isolated species was Campylobacter upsaliensis (6 [4%] of 155 isolates). The ability of laboratories to recover this species may be dependent on the culture conditions and the media used. Three dogs living in the households of 2 of these 6 patients had C. upsaliensis isolated in their stool specimens.

Limited transmission of multidrug-resistant tuberculosis despite a high proportion of infectious cases in Los Angeles County, California.

Preventing transmission of multidrug-resistant tuberculosis is critical because of treatment toxicity, cost, and the lack of effective therapy for latent infection. We attempted to determine the extent of transmission in Los Angeles County by comparing relatedness of multidrug-resistant tuberculosis cases using restriction fragment length polymorphism and by cross-matching contact information to the Tuberculosis Registry. Strain typing was done on isolates of 102 pulmonary multidrug-resistant cases identified between August 1993 and 1998. Seventy-one (70%) of the cases had cavitary lesions on chest radiograph, and 94 (92%) had sputa smear-positive for acid fast bacilli. Fifteen (15%) of the cases were known to be infected with human immunodeficiency virus. Four molecular clusters of two cases each and one closely related pair were identified among the 102 cases; contact investigation successfully identified all clusters but one. Among 946 contacts identified and cross-matched with the county's Tuberculosis Registry, one secondary case due to drug-resistant Mycobacterium bovis was found. To summarize, a very high proportion of pulmonary multidrug-resistant tuberculosis cases in Los Angeles County were infectious. Molecular strain typing indicated limited spread of disease, although it underestimated transmission compared with contact investigation. We believe aggressive surveillance and case management were critical to limiting the spread of multidrug- resistant tuberculosis.