Absence of wild poliovirus circulation among healthy children in a rural area with high oral poliovirus vaccination coverage.

Poliovirus circulation in a rural community was studied by a stool sample survey. No acute paralytic poliomyelitis case had been reported from the study area during the previous 5 months. Immunization coverage in age groups 7 to 12 months and 12 to 60 months was 95.8 and 94 per cent, respectively. Of the 257 children from whom stool samples were collected (about 6% of the child population), 161 (62.6%) were positive for virus isolation. Poliovirus was isolated from 60 (23.3%) children. All three poliovirus types were detected (41 type 1, 16 type 2 and 3 type 3). Intratypic differentiation tests classified these isolates as vaccine-like. Among the children excreting poliovirus, the proportion of those who did not receive polio vaccine within 30 days prior to the sample collection was 46.3, and 68.7 per cent for poliovirus type 1 and 2, respectively. It was concluded that these poliovirus excreting children were infected by the vaccine strains circulating in the environment. The survey showed that wild poliovirus was not detectable within five months after the last case of acute poliomyelitis. Displacement of the wild virus from the environment and circulation of vaccine virus was achieved by high vaccination coverage in this area.

An evaluation of cold chain in Maharashtra & Karnataka states by potency testing of field samples of oral poliovirus vaccine.

The cold chain for oral poliovirus vaccine was monitored in Maharashtra and Karnataka by potency testing of vaccine vials collected from various stages of the delivery system. Results showed that cold chain maintenance improved in the state of Maharashtra within a period of three years as the monitoring began in 1987. Of the 6289 samples of trivalent OPV collected from all 30 districts of the state during 1990 to 1992, 5834 (92.8%) had retained virus titre of at least 10(5.81) TCID50/dose. In comparison, 72 per cent of the 1660 samples collected from the state of Karnataka during the same period were found to contain this minimum required virus titre. Defects in cold chain maintenance in Karnataka could be demonstrated by plotting virus titre of samples of individual batches collected from different outlets. It was concluded that potency retesting of OPV samples for cold chain monitoring will ensure proper storage, transport and use of potent vaccine in the field.

Prevalence of antibodies to polioviruses & enteroviruses excreted by healthy children in Bombay.

A total of 132 healthy children between the ages one month and 12 yr were surveyed to determine the prevalence of antibodies to the three poliovirus serotypes. Among infants up to six months of age, 73.2, 85.4 and 56.1 per cent had antibodies to poliovirus types 1, 2 and 3, respectively. In children of age groups 7 months to 3 yr and above 3 yr, antibody prevalence to the three poliovirus serotypes was 90.2, 86.9 and 57.4, and 83.3, 96.7 and 76.7 per cent, respectively. Immunization coverage with three doses of OPV exceeded 85 per cent in children above 7 months of age. Low seroprevalence to type 3 poliovirus in the children was conspicuous. Of the 80 faecal samples studied from these children, 24 (30%) were positive for virus. Among these isolates, 16 were poliovirus type 1 and three type 2. Intratypic differentiation revealed that 15 of the 16 poliovirus type 1 isolates were of wild origin. Two out of the three poliovirus type 2 isolates were of oral poliovaccine origin. Our data indicate that in spite of good vaccination coverage wild poliovirus type 1 circulation was endemic in Bombay and; that a large number of children were susceptible to poliovirus type 3 infections.

Cytotoxic therapy. Role of durable venous access.

Aggressive chemotherapy regimens and supportive measures in haemato-oncology patients demand reliable venous access. Experience with this method in India has been limited. During a period of six months, we have used 42 subclavian indwelling catheters and 31 cubital Cavafix long lines. The mean age of patients in the two groups was 32 years and 7 years respectively. Subclavian catheters had a median duration of catheter placement of 46 days (range 4-145) and total 1494 catheter days, while cubital longlines yielded a median duration of insertion of 14 days (range 4-27) and total 508 catheter days. Catheter related complications were infection in 25% of patients, thrombophlebitis in 22%, blockade in 12% and misplacement in 17% in both groups taken together. The patients and families were extremely satisfied with the devices. Our experience supports further use of durable venous access in cancer patients. Implanted central venous catheters should be preferred whenever feasible.