Risk factors for HIV-1 and HIV-2 infection in pregnant women in Dakar, Senegal.

This study examines the prevalence and risk factors for Human Immunodeficiency Virus type 1 (HIV-1) and type 2 (HIV-2) infection in pregnant women in Dakar, Senegal. From April 1991 to January 1993, 9,518 pregnant women were interviewed and serologically tested for antibodies to HIV-1 and HIV-2; 26 (0.3%) were HIV-1 seropositive, 44 (0.5%) were HIV-2 seropositive, two (0.02%) were dually seropositive, and 9,448 (99.3%) were seronegative. Guinea-Bissau nationality and age > 25 years were associated with HIV-2 infection, whereas parity < or = 2 was associated with HIV-1 infection. Among women who gave birth to live infants, shorter length of union with the partner and having been married more than once were associated with HIV-2 infection, whereas age < or = 25 years was associated with HIV-1 infection. Information gained by this study may help target intervention strategies for preventing maternal HIV infection and understanding biological differences between the two viruses.

Experimental and natural infection with Bartonella henselae in domestic cats.

Domestic cats were experimentally infected with culture propagated Bartonella henselae by intradermal (i.d.) and intravenous (i.v.) routes. Cats were more efficiently infected by the i.d. (8/8 cats) than by the i.v. (2/16) route. Bacteremia was detected 1-3 weeks following inoculation and lasted for most cats for 1-8 months. However, one naturally infected cat was observed for 24 months and was found to be cyclically bacteremic, with bacterial levels varying one hundred fold or more from one period to another. No clinical or hematologic abnormalities were observed in any of the infected cats, even at the peak of bacteremia. Two cats that had become abacteremic were resistant to reinfection when inoculated with B. henselae a second time. Horizontal transmission through intimate contact between bacteremic and susceptible cats did not occur, and antibody positive bacteremic queens did not transmit the infection to their kittens in utero, peri-partum or post-partum. Only four of the 18 kittens acquired detectable levels of maternal antibody following nursing, which disappeared by 6 weeks of age. These studies indicate that B. henselae exists in an almost perfect host-parasite relationship with its feline host, but that most cats can ultimately rid themselves of the infection. The susceptibility of cats to intradermal infection and the lack of direct cat-cat transmission are compatible with possible arthropod vectors.

Bartonella henselae prevalence in domestic cats in California: risk factors and association between bacteremia and antibody titers.

The isolation of Bartonella henselae, the agent of cat scratch disease, from the blood of naturally infected domestic cats and the demonstration that cats remain bacteremic for several months suggest that cats play a major role as a reservoir for this bacterium. A convenience sample of 205 cats from northern California was selected between 1992 and 1994 to evaluate the B. henselae antibody and bacteremia prevalences and to determine the risk factors and associations between bacteremia and antibody titers. B. henselae was isolated from the blood of 81 cats (39.5%). Forty-two (52%) of these bacteremic cats were found to be infected with > or = 1,000 CFU/ml of blood. Impounded or former stray cats were 2.86 (95% confidence interval [CI] = 1.94, 4.22) times more likely to be bacteremic than the pet cats. Young cats ( < 1 year old) were more likely than adult cats to be bacteremic (relative risk = 1.64; (95% CI = 1.19, 2.28). Bacteremic cats were more likely than nonbacteremic cats to be infested with fleas (relative risk = 1.64; 95% CI = 1.38, 1.96). No association between B. henselae infection and feline immunodeficiency virus antibody prevalence was observed. Eighty-one percent of the cats (166 of 205) tested positive for B. henselae antibodies, and titers were higher in bacteremic than in nonbacteremic cats. Multiple logistic regression analysis indicated that younger age and seropositivity for B. henselae antibodies were associated with bacteremia. Serological screening for Bartonella antibodies may not be useful for the identification of bacteremic cats (positive predictive value = 46.4%), but the lack of antibodies to B. henselae was highly predictive of the absence of bacteremia (negative predictive value = 89.7%). Seronegative cats may be more appropriate pets for immunocompromised individuals who are at increased risk for developing severe B. henselae disease.

Experimental transmission of Bartonella henselae by the cat flea.

Bartonella henselae is an emerging bacterial pathogen, causing cat scratch disease and bacillary angiomatosis. Cats bacteremic with B. henselae constitute a large reservoir from which humans become infected. Prevention of human infection depends on elucidation of the natural history and means of feline infection. We studied 47 cattery cats in a private home for 12 months to determine the longitudinal prevalence of B. henselae bacteremia, the prevalence of B. henselae in the fleas infesting these cats, and whether B. henselae is transmitted experimentally to cats via fleas. Vector-mediated transmission of B.henselae isolates was evaluated by removing fleas from the naturally bacteremic, flea-infested cattery cats and transferring these fleas to specific-pathogen-free (SPF) kittens housed in a controlled, arthropod-free University Animal Facility. B. henselae bacteremia was detected in 89% of the 47 naturally infected cattery cats. A total of 132 fleas were removed from cats whose blood was simultaneously cultured during different seasons and were tested individually for the presence of B. henselae DNA by PCR. B. henselae DNA was detected in 34% of 132 fleas, with seasonal variation, but without an association between the presence or the level of bacteremia in the corresponding cat. Cat fleas removed from bacteremic cattery cats transmitted B. henselae to five SPF kittens in two separate experiments; however, control SPF kittens housed with highly bacteremic kittens in the absence of fleas did not become infected. These data demonstrate that the cat flea readily transmits B. henselae to cats. Control of feline infestation with this arthropod vector may provide an important strategy for the prevention of infection of both humans and cats.