Population-Based Incidence of Typhoid Fever in an Urban Informal Settlement and a Rural Area in Kenya: Implications for Typhoid Vaccine Use in Africa

Background: High rates of typhoid fever in children in urban settings in Asia have led to focus on childhood immunization in Asian cities, but not in Africa, where data, mostly from rural areas, have shown low disease incidence. We set out to compare incidence of typhoid fever in a densely populated urban slum and a rural community in Kenya, hypothesizing higher rates in the urban area, given crowding and suboptimal access to safe water, sanitation and hygiene. Methods: During 2007-9, we conducted population-based surveillance in Kibera, an urban informal settlement in Nairobi, and in Lwak, a rural area in western Kenya. Participants had free access to study clinics; field workers visited their homes biweekly to collect information about acute illnesses. In clinic, blood cultures were processed from patients with fever or pneumonia. Crude and adjusted incidence rates were calculated. Results: In the urban site, the overall crude incidence of Salmonella enterica serovar Typhi (S. Typhi) bacteremia was 247 cases per 100,000 person-years of observation (pyo) with highest rates in children 5–9 years old (596 per 100,000 pyo) and 2–4 years old (521 per 100,000 pyo). Crude overall incidence in Lwak was 29 cases per 100,000 pyo with low rates in children 2–4 and 5–9 years old (28 and 18 cases per 100,000 pyo, respectively). Adjusted incidence rates were highest in 2–4 year old urban children (2,243 per 100,000 pyo) which were.15-fold higher than rates in the rural site for the same age group

Crude and Adjusted Rates of S Typhi Bacteremia in Kibera.

<p>Crude and Adjusted Rates of S Typhi Bacteremia in Kibera.</p

Number of Cases of Typhoid fever and Rainfall Accumulation per Month, Kibera.

<p>Number of Cases of Typhoid fever and Rainfall Accumulation per Month, Kibera.</p

Figure 2.

<p>a) Flow Chart showing Numbers of Enrollees from Lwak, Blood Cultures Processed and Pathogens Isolated, Including <i>S</i> Typhi, Isolated. b) Flow Chart showing Numbers of Enrollees from Kibera, Blood Cultures Processed and Pathogens Isolated, Including <i>S</i> Typhi, Isolated.</p

Isolation rates for <i>S</i>. Typhi from blood cultures collected in Kibera and Lwak.

<p>*Proportion of pathogens isolated that were <i>S</i>. Typhi by age group.</p><p>**Proportion of blood cultures done from which <i>S</i>. Typhi was isolated.</p>&<p>Two patients had <i>S</i>. Typhi isolated from blood cultures twice during a seven day period (representing persistent bacteremia); for the purposes of these rate calculations, we excluded one of the blood cultures for each of these patients. We did not have age information for one of the patients.</p

<i>S</i>. Typhi isolates susceptible to a variety of antimicrobial drugs--Kibera and Lwak.

<p>a: test not done for 3 isolates.</p><p>b: tests not done for 4 isolates.</p

Map of Kenya with Insets Showing Location of Study Sites.

<p>Map of Kenya with Insets Showing Location of Study Sites.</p

Symptoms from data collected from clinic visit for 116 patients with <i>S.</i> Typhi bacteremia from Kibera and Lwak (from whom clinical data were available) compared with other patients with blood cultures processed.

<p>*p<0.001 when compared all patients without <i>S.</i> Typhi isolated from blood culture.</p><p>**p<0.01 when compared all patients without <i>S.</i> Typhi isolated from blood culture.</p><p>***p<u><</u>0.05 when compared all patients without <i>S.</i> Typhi isolated from blood culture.</p>&<p>p <0.05 when compared with patients with bacteremia due to pathogens other than <i>S</i>. Typhi.</p

Effectiveness of semen washing to prevent human immunodeficiency virus (HIV) transmission and assist pregnancy in HIV-discordant couples: a systematic review and meta-analysis

ObjectiveTo evaluate the effectiveness of semen washing in human immunodeficiency virus (HIV)–discordant couples in which the male partner is infected.DesignSystematic review and meta-analysis.SettingNot applicable.Patient(s)Forty single-arm open-label studies among HIV-discordant couples that underwent intrauterine insemination (IUI) or in vitro fertilization (IVF) with or without intracytoplasmic sperm injection (ICSI) using washed semen.Intervention(s)Semen washing followed by IUI, IVF, or IVF/ICSI.Main Outcome Measure(s)Primary outcome: HIV transmission to HIV-uninfected women; secondary outcomes: HIV transmission to newborns and proportion of couples achieving a clinical pregnancy.Result(s)No HIV transmission occurred in 11,585 cycles of assisted reproduction with the use of washed semen among 3,994 women. Among the subset of HIV-infected men without plasma viral suppression at the time of semen washing, no HIV seroconversions occurred among 1,023 women after 2,863 cycles of assisted reproduction with the use of washed semen. Studies that measured HIV transmission to infants reported no cases of vertical transmission. Overall, 56.3% of couples (2,357/4,184) achieved a clinical pregnancy with the use of washed semen.Conclusion(s)Semen washing appears to significantly reduce the risk of transmission in HIV-discordant couples desiring children, regardless of viral suppression in the male partner. There are no randomized controlled studies or studies from low-income countries, especially those with a large burden of HIV. Continued development of lower-cost semen washing and assisted reproduction technologies is needed. Integration of semen washing into HIV prevention interventions could help to further reduce the spread of HIV