Laboratory evaluation of a dot-blot enzyme immunoassay for serologic confirmation of illness due to Rickettsia conorii.

Of the 169 United States Army soldiers who deployed on a field training exercise to a remote area of Botswana for two weeks in January 1992, more than 30% developed a febrile illness within five days of their return. A diagnosis of South African tick typhus was suggested by soldiers' exposure to ticks, as well as the presence of eschars and vesicles at the site of tick bites, and tender regional lymphadenopathies. This high attack rate, experienced during such a short exposure period, emphasizes the hazard of illness due to Rickettsia conorii to persons visiting endemic areas. A rapid, diagnostic, semiquantitative enzyme immunoassay (DS) for detection of IgG and IgM antibodies to R. conorii was performed on 209 acute and convalescent sera from soldiers in the outbreak and on 75 control sera. For the acute sera from soldiers meeting the probable case definition of having both regional lymphadenopathy and tick bite eschar, as judged by an IgG indirect fluorescent antibody (IFA) test, the resulting sensitivity and specificity of the DS test were 100% and 48%, respectively. In the analysis of the acute sera, the DS test identified as reactive more of the probable cases (62%) than either the IgG (16%) or IgM (55%) IFAs. This simple and rapid diagnostic test could be useful in establishing a preliminary diagnosis of R. conorii rickettsiosis in remote settings when immediate confirmation by IFA is impossible.

Decreases in invasive Haemophilus influenzae diseases in US Army children, 1984 through 1991.

OBJECTIVE: To document trends in the incidence of invasive Haemophilus influenzae diseases in young children of US Army active duty soldiers following the publication of H influenzae type b immunization recommendations for young children between 1985 and 1990. DESIGN: A population-based surveillance of hospital discharge diagnoses for H influenzae invasive diseases. SETTING: Military and civilian medical treatment facilities around the world. PATIENTS: There was a mean population of nearly 200,000 US Army health care beneficiaries younger than 5 years of age each year of the study. OUTCOME MEASURES: Annual total and age-specific incidences of the six most common H influenzae invasive diseases in this population (meningitis, epiglottitis, septicemia, pneumonia, cellulitis, and septic arthritis). RESULTS: The annual number of cases of H influenzae invasive diseases decreased from a high of 188 in 1986 to 43 in 1991. The incidence in the age group at highest risk for H influenzae disease, those 6 to 11 months of age, decreased from 355 per 100,000 children in 1986 to 116 per 100,000 in 1991 (P < .0001, chi 2 for trend). The incidence for H influenzae meningitis declined from 59 per 100,000 children in 1986 to 6 per 100,000 in 1991 (P < .0001, chi 2 for trend). CONCLUSIONS: The decrease in H influenzae invasive diseases closely follows the dates of H influenzae type b vaccine licensure for use in progressively younger age groups. Some age groups, however, experienced a decline in disease rates even before becoming eligible for vaccination.