Dynamics of transmission of Trypanosoma cruzi in a rural area of Argentina: III. Persistence of T. cruzi parasitemia among canine reservoirs in a two-year follow-up

A new cross-sectional survey of household- associated mongrel dogs as well as follow-up of previously parasitemic individuals was carried out in 1984 toy means of xenodiagnosis and serologic techniques to get a deeper insight into the relationship of T. cruzi parasitemia and age among canine hosts in a rural area of Argentina. Persistence of detectable parasitemia was age-independent, or at most, loosely related to age, confirming the pattern observed in 1982. Similarly no significant age-decreasing effect was recorded among seropositive dogs in: a) the probability of detecting parasites in a 2-year follow-up; b) their intensity of infectiousness (=infective force) for T. infestans 3rd-4th instar nymphs, as measured by the percentage of infected bugs observed in each dog xenodiagnosis. Moreover, not only was the infective force of seropositive dogs for bugs approximately constant through lifetime, but it was significantly higher than the one recorded for children in the present survey, and for human people by other researchers. Therefore, and since T. infestans field populations show high feeding frequencies on dogs, the latter are expected to make the greatest contribution to the pool of infected vectors in the rural household of Argentina. This characteristic should be sufficient to involve canine reservoirs definitely as a risk factor for human people residing in the same house. The increased severity of parasitemia observed among dogs in this survey may be related to the acute undernutrition characteristic of canine populations of poor rural areas in our country, which is expected to affect the ability of the host to manage the infection.

Antibody response to heat-inactivated hepatitis B vaccine (CLB-3mg) in hemodialysis patients and occupational risk personnel: a one year follow-up

Immune response against hepatitis B vaccine (CLB 3mg) was evaluated in 59 hemodialysis patients and 20 occupational risk personnel. Seroconversion was induced in 52.5% and 70.0% respectively. Twelve months after the first dose, 37.5% of patients and 60.0% of occupational risk personnel had detectable anti-HBs level. Antibody level was expressed in sample ratio units (SRU). Considering only the responders, in the patients group 38.7% had a low anti-HBs response (2.1-9.9 SRU) 32.3% a medium response (10-99.9 SRU) and 29.0% a high response (>100 SRU) while in occupational risk personnel these values were 14.3%, 64.3% and 21.4% respectively. The authors suggest the use of HBV vaccines with more elevated HBsAg concentration or a reinforced immunization schedule to improve the anti-HBs response not only for patients but also for healthy persons.

Occupational and domiciliary contact with dogs as factors of risk to human infection with Toxocara larvae

The contact with dogs at home or place of work has been investigated as factors of risk in the occurrence of the visceral larva migrans syndrome caused by Toxocara, in man. Through the E.L.I.S.A. (enzyme-linked immunosorbent assay) technique, the presence of antibodies to Toxocara was searched in the sera of 79 women who have been raising or had raised dogs at home in the last two years and 123 men, who were municipal public employees in charge of the capture and keeping of stray dogs. The control groups were constituted by 205 sera from women who denied domiciliary contact with dogs, at least in the last two years, and 139 sera from men whose occupation did not urge them to contact with dogs. A significant more elevated frequency of antibodies to Toxocara was observed among women with domiciliary contact with dogs; nevertheless, there was not a significant difference in the positive rates in the case of men with occupational contact with dogs.

Exposure to acellular blood products and risk of HIV infection in hemophiliacs from Belo Horizonte, Brazil

Results of a HIV prevalence study conducted in hemophiliacs from Belo Horizonte, Brazil are presented. History of exposure to acellular blood components was determined for the five year period prior to entry in the study, which occurred during 1986 and 1987. Patients with coagulations disorders (hemophilia A = 132, hemophilia B = 16 and coagulation disorders other than hemophilia = 16) were transfused with liquid cryoprecipitate, locally produced, lyophilized cryoprecipitate, imported from São Paulo (Brazil) and factor VIII and IX, imported from Rio de Janeiro (Brazil), Europe, and United States. Thirty six (22%) tested HIV seropositive. The univariate and multivariate analysis (logistic model) demonstrated that the risk of HIV infection during the study period was associated with the total units of acellular blood components transfused. In addition, the proportional contribution of the individual components to the total acellular units transfused, namely a increase in factor VIII/IX and lyophilized cryoprecipitate proportions, were found to be associated with HIV seropositivity. This analysis suggest that not only the total amount of units was an important determinant of HIV infection, but that the risk was also associated with the specific component of blood transfused