Predominance of CRF02-AG and CRF06-cpx in Niger,West Africa

A total of 110 HIV-1-positive samples obtained in 1997 (n = 44) and 2000 (n = 66) were genetically characterized in the V3-V5 envelope region and the p24 gag region. The majority of the strains were CRF02-AG (54.3%) or CRF06-cpx (18.1%) in env and gag. More than 9% of the samples were recombinants between CRF02 and CRF06; 9 were CRF06 in env but CRF02 in gag, and for one sample the opposite was seen. Overall for 23 (20.9%) samples, the subtype designation was different between env and gag, and in 20 of these 23 samples a CRF was involved in the recombination event. No significant differences were seen between subtype distributions in 1997 and 2000, except that the proportion of recombinants increased from 13.6% in 1997 to 27.2% in 2000.     

Traditional medicine to DNA vaccines: the advance of medical research in West Africa

Summary West Africa has a rich medical history. Herbal medicine has been practiced for hundreds of years and the establishment of an effective herbal pharmacopoeia was probably the first medical research carried out in West Africa. Arabic medicine was practiced in the countries of the Sahel in the 15th and 16th centuries. The coming of the Europeans focused research on infectious diseases such as malaria, yellow fever and sleeping sickness, to which Europeans were very susceptible and which caused devastating epidemics among the populations of their new colonies. The end of the colonial era saw the establishment of a few large, well-equipped teaching hospitals but these proved too expensive for the newly independent states of West Africa to run effectively, and the second generation of West African medical schools was based on more modest government hospitals. This led to a change in the focus of research away from the more unusual conditions seen in a specialist referral hospital to an interest in conditions, such as the common infectious diseases, seen more frequently in district hospitals. The advent of the primary health care movement in the 1970s was followed by an increased emphasis on community studies. Molecular biology is likely to have an enormous impact on medicine in general in the coming years. One of the main challenges facing medical researchers in West Africa is how these new technologies can be used most effectively to improve health in countries with limited resources.     

Intensified pulse polio immunisation coverage in slums of a metropolitan city: an appraisal

A study was conducted by house-to-house visit during 2nd and 3rd round of IPPI in Nov and Dec 2000 in two slums adjacent to Medical College Kolkata. Total houses visited in these two rounds were 2836 and 611 children were immunised at home. Mothers of 503 children (who did not receive IPPI dose at booth on NIDs) were interviewed. For rest 104 children, mothers were not available during the time of visit. The result showed that infants were the largest group (30.6%) to receive vaccine at home. Majority (84.1%) was permanent residents of the locality. Only 4.2% were Bengali-speaking Hindus while most other were Hindi or Urdu speaking Muslims. "Health workers will bring vaccine at door steps" was the reason of non-attendance at booth by 30.2% parents. No routine immunisation was received by 14.9% children. The source of information regarding IPPI was, 45.4% from medical students, 28.5% from health workers, 15.1% from TV, 5.6% from relatives and neighbours, 3.6% from miking and 1.8% from newspapers respectively.     

Improving immunization coverage in rural areas of Ecuador: a cost-effectiveness analysis

This study describes the costs and outcomes of two different immunization strategies used by the district level of the Ministry of Health carried out between 1993 and 1995 in Low-Napo area, Napo, Ecuador. One was centrally planned and managed by the District Hospital (DH) and the other planned and implemented together with community health workers (CHW). Immunization costs were estimated directly from survey records and communication of the Ministry of Health. Outcomes information was abstracted from the vaccination statistics of the Napo Province Health Department for 1993/1995. Community health workers strategy immunized 113 children with an average cost of US $32 per child. District Hospital strategy had an average cost of US $777.6 per immunized child.Thus, CHWs strategy is more effective and less costly than the DH strategy.This study shows that in order to maximize the cost-effectiveness of immunization, it is important to involve community participation in both planning and implementation. Continuous follow-up and evaluation of the immunization programme and further research on vaccine efficacy are necessary in order to maintain these results.     

Emergence of complex and diverse CRF02-AG/CRF06-cpx recombinant HIV type 1 strains in Niger,West Africa

On the basis of partial env and gag subtyping, we documented that the majority of HIV-1 strains circulating in Niger were CRF02-AG (54.3%) or CRF06-cpx (18.1%) and that 9% of the samples were possible recombinants between CRF02 and CRF06. To determine in more detail the precise structure of these viruses we sequenced the full-length genomes for three such strains (97NE-003, 00NE-036, and 00NE-095). From the bootscan and phylogenetic tree analysis it is evident that the new viruses are the result of recombination events between CRF02-AG and CRF06-cpx strains. Importantly, each virus had a different complex recombinant structure with multiple breakpoints, leading to viruses with complex mosaic patterns.     

Intussusception in southern Indian children: lack of association with diarrheal disease and oral polio vaccine immunization.

BACKGROUND: Intussusception is the most common cause of intestinal obstruction in young children and has been reported as a complication of a recently withdrawn tetravalent reassortant rotavirus vaccine. METHODS: We studied the history, clinical presentation, management and outcome of intussusception presenting to a tertiary care hospital in southern India over a 10-year period, in order to assess potential association with diarrheal disease and immunization. RESULTS: Data from 137 index cases and 280 control subjects indicated that the risk of diarrheal disease or oral polio vaccine administration in the month prior to presentation was similar in the index cases and controls. Mean time to presentation to hospital after developing symptoms was 1.8 days, and 77.3% of patients required surgery, with 47.4% undergoing intestinal resection. Mortality was 0.006%. CONCLUSIONS: No association could be demonstrated between gastroenteritis or oral poliovirus vaccine immunization and intussusception in southern Indian children. These children presented later and required operative intervention more frequently than has been reported in other studies, but had a good outcome with low mortality.     

A randomized clinical trial of acellular pertussis vaccines in healthy adults: dose-response comparisons of 5 vaccines and implications for booster immunization.

The safety and immunogenicity of 5 acellular pertussis vaccines (ACVs) were compared in a multicenter, randomized, double-blind trial. A total of 481 healthy adults were given a single intramuscular booster dose of ACV or placebo. Three different dose levels were tested for 4 ACVs: full strength (the dose level proposed for infant immunization), one-third strength, and one-tenth strength. For 1 multicomponent vaccine, only the pertussis toxoid dose level varied. Minor injection site reactions were common and similar in frequency among vaccinated groups. Late-onset injection site reactions were seen in all ACV groups. Dose-related increases in mean antibody titers against vaccine antigens were seen after immunization with all ACVs. Antibody responses against antigens not known to be present in the vaccines were detected after immunization with 4/5 ACVs. Antibody levels fell significantly during the year after immunization. These data support evaluation of ACVs for broader use among adolescents and adults.     

Rift Valley fever in West Africa: the role of space in endemicity

Rift Valley fever is an endemic vector-borne disease in West Africa, which mainly affects domestic ruminants and occasionally humans. The aetiological mechanisms of its endemicity remain under debate. We used a simple spatially explicit model to assess the possibility of endemicity without wild animals providing a permanent virus reservoir. Our model takes into account the vertical transmission in some mosquito species, the rainfall-driven emergence of their eggs and local and distant contacts because of herd migration. Endemicity without such a permanent virus reservoir would be impossible in a single site except when there is a strictly periodic rainfall pattern; but it would be possible when there are herd movements and sufficient inter-site variability in rainfall, which drives mosquito emergence.     

Epidemic cholera in Guinea-Bissau: The challenge of preventing deaths in rural West Africa

Objectives: An epidemiologic investigation was conducted to identify factors associated with cholera mortality in a rural African setting and interventions likely to prevent deaths in future epidemics.Methods: The authors reviewed surveillance data from rural Biombo, Guinea-Bissau, interviewed family members of persons who died of cholera, and conducted a case-control study in the catchment area of a health center with a high case:fatality ratio (CFR).Results: Forty-three deaths occurred among the 1169 persons who reported to health centers with cholera during the epidemic (CFR = 3.7%). Delayed rehydration and over-hydration probably contributed to 10 of these deaths. An additional 19 cholera deaths occurred outside health centers. In the case-control study, persons with cholera who died were 5.4 times (95% CI = 1.0–53.4) more likely to be in poor health or intoxicated at illness onset than persons with cholera who survived. Fatal cases were 6.0 times (95% CI = 1.1–60.8) more likely to not attend the health center than survivors.Conclusions: The low overall CFR in Biombo, compared to CFRs reported during other epidemics in sub-Saharan Africa, suggests that medical care provided at rudimentary rural health centers prevented numerous deaths. Additional deaths may be prevented by strengthening the infrastructure of halth services in the rural areas and by enhanced public education regarding the need for persons with cholera to promptly seek medical care.     

Improving malaria control in West Africa: interruption of transmission as a paradigm shift

With the paradigm shift from the reduction of morbidity and mortality to the interruption of transmission, the focus of malaria control broadens from symptomatic infections in children ≤5 years of age to include asymptomatic infections in older children and adults. In addition, as control efforts intensify and the number of interventions increases, there will be decreases in prevalence, incidence and transmission with additional decreases in morbidity and mortality. Expected secondary consequences of these changes include upward shifts in the peak ages for infection (parasitemia) and disease, increases in the ages for acquisition of antiparasite humoral and cellular immune responses and increases in false-negative blood smears and rapid diagnostic tests. Strategies to monitor these changes must include: (1) studies of the entire population (that are not restricted to children ≤5 or ≤10 years of age), (2) study sites in both cities and rural areas (because of increasing urbanization across sub-Saharan Africa) and (3) innovative strategies for surveillance as the prevalence of infection decreases and the frequency of false-negative smears and rapid diagnostic tests increases.