The viral etiology of acute respiratory infections in children in Uganda.

The role of viruses in respiratory diseases of young children in Uganda was studied. A viral etiology was established in 36% of the infections investigated. The most important pathogens were found to be respiratory syncytial virus and parainfluenza viruses, which were responsible for 26% of infections investigated. They caused both upper and lower respiratory tract diseases. There was little or no seasonal variation in the etiology of these infections. Adenoviruses were found to be less important and were etiologically related to only 4% of respiratory disease cases. Influenza viruses and enteroviruses were also found to be associated with respiratory infections. However, they were less frequent and their role was insignificant. The role of multiple virus infections was also insignificant.

Some characteristics of poliovirus strains isolated in Uganda between 1966 and 1971.

Sixty-five poliovirus strains were investigated in genetic marker tests in order to obtain information on the characteristics of polioviruses circulating in Uganda where, owing to the insufficient use of live poliovirus vaccine, poliomyelitis remained a serious public health problem. Of the type 1 strains predominant in both epidemic and non-epidemic years, 29 were studied for their antigenic fine structure. Based on their intratypic character, these strains proved to represent six different antigenic variants. Three of these variants were predominant during certain periods; the first variant was present in 1966 and 1968, the second in 1967, and the third from 1969 to the end of observation period. Four strains from Kuwait and three from Ghana isolated in 1969 and 1970 showed an antigenic structure identical to that of the strains predominant in Uganda in these years. Some strains proved to be of vaccine origin. Twenty-nine type 1 and 24 type 2 strains showed a great variety of characteristics when studied in d, od, and rct/40 marker tests. There was no indication that the distribution of strains according to their in vitro markers would have been different in epidemic and non-epidemic years, or that any particular combination of markers would have been more common among strains isolated from paralytic patients than among those from non-paralytic patients. Nine of 12 type 3 strains had the rct/40(+) marker.

Passive immunization in experimental Herpesvirus hominis infection of newborn mice.

Infection of newborn mice with Herpesvirus hominis type 2(HVH-2) was used as an experimental model of disseminated HVH infection in newborn humans. Mice were challenged with 103 plaque-forming units of HVH-2 intranasally and were given 0.2 ml of rabbit serum intraperitoneally. Passive immunizations with rabbit anti-HVH-2 serum resulted in a significant decrease in mortality and prolongation of survival time. This effect correlated with the neutralizing antibody titer of the serum against HVH-2 and was more pronounced when immune serum was administered 1 h after infection as compared with 24 h. These results suggest that administration of high-titer anti-HVH-2 immunoglobulins shortly after delivery could afford significant protection to the newborn of a mother with genital HVH-2 infection.

Factors affecting the efficacy of live poliovirus vaccine in warm climates. Efficacy of type 1 Sabin vaccine administered together with antihuman gamma-globulin horse serum to breast-fed and artificially fed infants in Uganda.

A virologically controlled field trial was conducted with live monovalent type 1 poliovirus vaccine in children aged 3-30 months living in a rural area of Uganda, in an attempt to find out the reason for the poor efficacy of such vaccine often observed in countries with a warm climate. Groups of breast-fed and of artificially fed infants received the vaccine orally, either alone or mixed with horse serum prepared against partly purified human gamma-globulin. Irrespective of the diet, the "take rate"-measured by the rates of vaccine virus excretion and of antibody conversion-was found to be poor when the vaccine was given alone but satisfactory when it was given together with the horse antiserum. However, the extent and duration of vaccine virus multiplication in the intestinal tract proved to be limited and the mean antibody level elicited by the vaccination, irrespective of the schedule of vaccine administration, was low. These results, besides indicating that breast-feeding does not influence the efficacy of vaccination in the age groups studied, revealed the presence of an inhibitor in the alimentary tract. This inhibitor acts against the multiplication of vaccine virus, which may be blocked by antibodies in the horse antiserum for a limited period at the time of vaccination. Interference between the enteroviruses and the vaccine strain was also found to be responsible for decreasing the efficacy of vaccination, though its role was secondary to that of the inhibitor. Revaccination experiments showed that the effects of both inhibitor and interference may be overcome by repeated administration of the vaccine.

Influenza in East Africa, 1969-70.

Very little information is available concerning the frequency of influenza in East Africa. Following recent outbreaks of influenza in Uganda, that were due to the A2/Hong Kong/68 virus, it was considered useful to obtain information relating to the prevalence of infection due to this virus and to the current strain of influenza B virus, not only in Uganda but also in the neighbouring territories of Kenya and Tanzania. The results of serological testing of sera showed that widespread outbreaks of influenza A2/Hong Kong/68 infection had occurred recently in all three territories, while there was evidence of sporadic infection in all territories by the current influenza B strain. Despite the favourable climate of East Africa, it is evident that widespread outbreaks of influenza can occur, and these may arise during the period of the year when influenza is rare in countries with temperate climates. Influenza can easily spread to other countries via air travellers to and from East Africa.