Environmental surveillance of wild poliovirus circulation in Egypt--balancing between detection sensitivity and workload

Examination of sewage specimens for poliovirus (environmental surveillance) was adopted as a supplementary tool in the surveillance of poliomyelitis in Egypt. Sewage samples were concentrated about 50-fold using a simple two-phase separation technique, and inoculated in cell cultures in two collaborating laboratories in parallel. All but 9 of the 293 (97%) samples collected from January 2001 to December 2002 contained poliovirus and/or other enteroviruses, with polioviruses being detected in 84% of the samples. The proportion of specimens containing type 1 wild poliovirus (PV1W, the North-East African (NEAF) genotype) was less in 2002 (16%) than in 2001 (57%), and further decreased in 2003. While the overall sensitivity to detect PV1W was similar in the two collaborating laboratories, the specimens scored positive were not identical. Parallel cultures inoculated with aliquots of a given specimen very frequently resulted in isolation of different viruses. Moreover, partial sequence analysis occasionally revealed representatives of different genetic lineages of PV1W in a given specimen. These results emphasize the need to use intensive laboratory analysis to optimise sample sensitivity in environmental poliovirus surveillance, and the difficulties in reproducing the isolation results by simple re-inoculation of samples containing a mixture of different viruses.

Epidemic transmission of human immunodeficiency virus in renal dialysis centers in Egypt

In 1993 an epidemic of human immunodeficiency virus (HIV) infection occurred among 39 patients at 2 renal dialysis centers in Egypt. The centers, private center A (PCA) and university center A (UCA) were visited, HIV-infected patients were interviewed, seroconversion rates at UCA were calculated, and relatedness of HIV strains was determined by sequence analysis; 34 (62%) of 55 patients from UCA and 5 (42%) of 12 patients from PCA were HIV-infected. The HIV seroconversion risk at UCA varied significantly with day and shift of dialysis session. Practices that resulted in sharing of syringes among patients were observed at both centers. The analyzed V3 loop sequences of the HIV strain of 12 outbreak patients were >96% related to each other. V3 loop sequences from each of 8 HIV-infected Egyptians unrelated to the 1993 epidemic were only 76%-89% related to those from outbreak strains. Dialysis patients may be at risk for HIV infection if infection control guidelines are not followed.

Cluster survey evaluation of coverage and risk factors for failure to be immunized during the 1995 National Immunization Days in Egypt

BACKGROUND

In 1995, Egypt continued to experience endemic wild poliovirus transmission despite achieving high routine immunization coverage with at least three doses of oral poliovirus vaccine (OPV3) and implementing National Immunization Days (NIDs) annually for several years.

METHODS

Parents of 4188 children in 3216 households throughout Egypt were surveyed after the second round of the 1995 NIDs.

RESULTS

Nationwide, 74% of children are estimated to have received both NID doses, 17% one NID dose, and 9% neither NID dose. Previously unimmunized (47%) or partially immunized (64%) children were less likely to receive two NID doses of OPV than were fully immunized children (76%) (P < 0.001). Other risk factors nationwide for failure to receive NID OPV included distance from residence to nearest NID site >10 minute walk (P < 0.001), not being informed about the NID at least one day in advance (P < 0.001), and residing in a household which does not watch television (P < 0.001). Based on these findings, subsequent NIDs in Egypt were modified to improve coverage, which has resulted in a marked decrease in the incidence of paralytic poliomyelitis in Egypt.

CONCLUSIONS

In selected situations, surveys can provide important information that is useful for planning future NIDs.

Progress toward poliomyelitis eradication in the Eastern Mediterranean Region of the World Health Organization

The Eastern Mediterranean Region (EMR) of the World Health Organization has made substantial progress toward eradicating poliomyelitis. From 1988 to 1995, the number of confirmed cases of polio decreased 66%, from 2342 to 789. National immunization days were conducted in 18 (78%) of the 23 countries in 1995, representing 88% of the regional population. By 1995, 20 countries (87%) in the EMR had established systems for reporting acute flaccid paralysis (AFP), 20 (87%) were investigating AFP or polio cases epidemiologically, 18 (78%) had initiated follow-up at 60 days to confirm or discard suspected polio cases, 7 (30%) had achieved nonpolio AFP rates of > or = 1.0/100,000 children <15 years of age (a measure of the sensitivity of surveillance), and 16 (70%) had made laboratory investigations of polio cases for 1281 (74%) of the 1715 AFP cases reported in the EMR. Despite significant progress, the success of the polio eradication initiative in the EMR will depend on finding solutions to a number of technical, managerial, political, and financial challenges.

A controlled field trial of live Salmonella typhi strain Ty 21a oral vaccine against typhoid: three-year results

A controlled field trial of Salmonella typhi strain Ty 21a oral vaccine against typhoid was carried out in Alexandria, Egypt, from March 1978 to March 1981. A total of 32,388 children was included in the study. The children were divided in two comparable groups, one given three doses of vaccine and the other three doses of placebo. Each dose of vaccine contained 1-8 X 10(9) live Ty 21a bacteria. The population was monitored, and each suspected case of typhoid was investigated bacteriologically and serologically. The effectiveness of the vaccine was assessed by analyzing the number of confirmed cases of typhoid fever in the two groups. The incidence of typhoid fever was 4.9 cases per 10,000 children per year in the control group and 0.2 cases per 10,000 children per year in the vaccine group. The results indicate that, in the dose schedule used, the Ty 21a mutant strain, which is stable and safe, is protective for a period of at least three years.

A controlled field trial of liver oral typhoid vaccine Ty21a

A controlled field trial of a live oral typhoid vaccine was carried out in Alexandria, Egypt, in 1978-79. A total of 32 388 children were included in the study. They were divided in two comparable groups, one given 3 doses of the vaccine and the other 3 doses of the placebo. Each active dose contained 1 x 10(9)-8 x 10(9) live Ty21a bacteria. From March 1978 to March 1979, the population studied was followed up and suspected typhoid cases were investigated bacteriologically and serologically. The effectiveness of the vaccine was assessed by analysis of the incidence of typhoid fever in the two groups. The results of the follow-up indicate that, in the dosage schedule used, the Ty21a mutant strain, found previously to be stable and safe, is protective against typhoid fever for at least one year.

A second controlled field trial of a serogroup A meningococcal polysaccharide vaccine in Alexandria

The encouraging results of an earlier controlled field trial of the serogroup A meningococcal polysaccharide vaccine in the prevention of clinical disease prompted this study, the aim of which was to evaluate further the effectiveness of another lot of this type of vaccine, the duration of immunity, and the effectiveness against meningococcal carriage. A controlled field trial was carried out in early 1973 on 176 646 schoolchildren 6-15 years of age, of whom half received the serogroup A polysaccharide vaccine and the other half tetanus toxoid as a control. The incidence of cerebrospinal meningitis caused by serogroup A meningococci was 89% lower in the immunized group than in the controls for one year only. With regard to its effect on carriage, the vaccine was found to reduce to less than half the rate of new acquisition of serogroup A meningococci during the period immediately following immunization. The duration of the carrier state was also shortened in the immunized group.

Controlled field trial of a typhoid vaccine prepared with a nonmotile mutant of Salmonella typhi Ty2

A controlled field trial was performed in Egypt to evaluate a whole cell typhoid vaccine prepared with a nonmotile mutant of S. typhi Ty2 (TNM1) devoid of flagellar antigen. This vaccine did not elicit an H antibody response, but significant Vi and O agglutinin responses were observed. There were 34 typhoid cases among 21 063 six- to seven-year-old children who received the TNM1 vaccine, and 44 cases among 21 017 children in the control group who received tetanus toxoid. These results suggest that TNM1 vaccine does not provide protection against typhoid fever, and that H antigen may be an important component of an effective vaccine.

A controlled field trial of a serogroup A meningococcal polysaccharide vaccine

A controlled field trial of a serogroup A meningococcal polysaccharide vaccine was conducted at three locations in Egypt during the winter cerebrospinal meningitis (CSM) season of 1971-72. The study population consisted of schoolchildren 6-15 years of age. No cases of serogroup A meningococcal CSM occurred in the group of students vaccinated with the test vaccine whereas 8 cases occurred in the control group vaccinated with tetanus toxoid, and 151 cases occurred in an unvaccinated contrast group. The case rate was significantly different between the test and control groups as well as between the test and contrast groups but was similar between the control and contrast groups. The previously demonstrated safety of the vaccine was confirmed. A significant serological response was elicited in the majority of the vaccinated students.