The 5q31 region in two African populations as a facet of natural selection by infectious diseases.

Cases of extreme natural selection could lead either to rapid fixation or extinction of alleles depending on the population structure and size. It may also manifest in excess of heterozygosity and the locus concerned will be displaying such drastic features of allele change. We suspect the 5q31 in chromosome 5 to mirror situation of such extreme natural selection particularly that the region encompasses genes of type 2 cytokine known to associate with a number of infectious and non-infectious diseases. We typed two sets of single nucleotide polymorphisms (SNPS) in two populations: an initial limited set of only 4 SNP within the genes of IL-4, IL-13, IL-5 and IL-9 in 108 unrelated individuals and a replicating set of 14 SN P in 924 individuals from the same populations with disregard to relatedness. The results suggest the 5q31 area to be under intense selective pressure as indicated by marked heterozygosity independent of Linkage Disequilibrium (LD); difference in heterozygosity, allele, and haplotype frequencies between generations and departure from Hardy-Weinberg expectations (DHWE). The study area is endemic for several infectious diseases including malaria and visceral leishmaniasis (VL). Malaria caused by Plasmodiumfalciparum, however, occurs mostly with mild clinical symptoms in all ages, which makes it unlikely to account for these indices. The strong selection signals seems to emanate from recent outbreaks of VL which affected both populations to varying extent.

Rehabilitation of the expanded programme on immunization in Sudan following a poliomyelitis outbreak.

In 1993 a large outbreak of paralytic poliomyelitis occurred in Sudan as a result of an accumulation of large numbers of susceptible children that was accelerated by faltering immunization services. The extent of the outbreak led to the rapid rehabilitation of Sudan's Expanded Programme on Immunization (EPI); the government began financing vaccine purchase, operational aspects of EPI were decentralized, vaccine delivery was changed from a mobile to a fixed-site strategy, a solar cold chain network was installed, inservice training was resuscitated, and social mobilization was enhanced. National immunization days (NIDs) for poliomyelitis eradication were conducted throughout the country, including the southern states during a cease fire in areas of conflict. Measles immunization coverage was increased by offering measles vaccine during the second round of NIDs and subsequently through routine immunization services. Supplemental tetanus toxoid immunization of women of child-bearing age began in three provinces at high risk for neonatal tetanus. From 1994 to 1996 reported immunization coverage increased and the incidence of all EPI target diseases fell. Trends in coverage, disease incidence, financing, and the implementation of WHO-recommended disease-control strategies suggest that more sustainable immunization services have been re-established in Sudan.

PIP: A large outbreak of paralytic poliomyelitis in 1993 in the Sudan prompted rapid rehabilitation of Sudan's Expanded Program on Immunization (EPI). A World Health Organization team visited Sudan in 1993, 1995, and 1996 to review such efforts and their impact. Measures taken to eradicate poliomyelitis, control measles, and eliminate neonatal tetanus included government financing of vaccine purchase, decentralization of EPI operations, a shift from a mobile to a less expensive fixed-site vaccine delivery strategy, installation of a solar cold chain network, resumption of managerial in-service training, and social mobilization. National immunization days were conducted in 1994, 1996, and 1997 throughout the country (during a cease fire in the southern areas). From 1993-96, reported infant immunization coverage increased for all antigens, with a concomitant decrease in the incidence of EPI target diseases. National coverage for the third dose of diphtheria-tetanus-pertussis increased from 51% in 1993 to 79% in 1996, while the proportion of immunizations delivered at fixed sites rose from 35% to 70%. By 1996, 19 of Sudan's 26 states were financing some of the operational costs for EPI.