An explosive, common-source outbreak of pneumonia caused by a previously unrecognized bacterium affected primarily persons attending an American Legion convention in Philadelphia in July, 1976. Twenty-nine of 182 cases were fatal. Spread of the bacterium appeared to be air borne. The source of the bacterium was not found, but epidemiologic analysis suggested that exposure may have occurred in the lobby of the headquarters hotel or in the area immediately surrounding the hotel. Person-to-person spread seemed not to have occurred. Many hotel employees appeared to be immune, suggesting that the agent may have been present in the vicinity, perhaps intermittently, for two or more years.

No abstract

Amblyomma americanum is a likely secondary vector of Lyme disease in New Jersey. Ticks of this species were removed from the site of the characteristic skin lesion known as erythema chronicum migrans on two patients with the disease, and the Lyme disease spirochete was isolated from nymphs and adults of this species. That A. americanum is a potential vector is supported by its similarities to Ixodes dammini, the known tick vector, in seasonal distribution and host utilization. The extensive range of A. americanum may have great implications for potential Lyme disease transmission outside known endemic areas.

In the fall of 1985, an outbreak of giardiasis occurred among several swimming groups at an indoor pool in northeast New Jersey. Nine clinical cases were identified, eight of whom had Giardia positive stool specimens. All were female; seven were adults (>18 years) and two were children. The attack rate was highest (39 per cent, 5/13) for the ladies lap group who had exposure on one day. These cases had no direct contact with children or other risk factors for acquiring Giardia. Infection most likely occurred following the ingestion of swimming pool water contaminated with Giardia cysts. The source of Giardia contamination was a handicapped child who had a fecal accident in the pool. He was a member of a group that IntroductionTransmission of Giardia lamblia occurs by ingestion of cysts in fecally contaminated water, and less often from fecally contaminated food.' The parasite can also be transmitted from person to person via an infected individual; this often occurs in institutions and day care centers.2The majority of reported outbreaks of Giardia have been

Over a four-year period in a five-county area, 71 patients with clinical hepatitis B had dental work performed in the two to six months before their illness. Fifty-five cases were traced to a single oral surgeon. Seventy-nine per cent of these patients were positive for hepatitis B surface antigen (HBsAg) and most had no other recognized source of hepatitis. An investigation of the implicated dentist uncovered no gross inadequacies in instrument sterilization or general dental procedures; however, the dentist was found to be an asymptomatic carrier of HBsAg of the same subtype (ay) as nine of 11 of his patients who had hepatitis and whose serums were available for testing. Since no HBSAg was found in the dentist's saliva, urine or feces, and since he admitted to having frequent cuts on his fingers, it is possible that a "hemoral" transmission of HBs Ag produced hepatitis in his patients.