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

Use of population-based surveillance to define the high incidence of shigellosis in an urban slum in Nairobi, Kenya.

BACKGROUND: Worldwide, Shigella causes an estimated 160 million infections and >1 million deaths annually. However, limited incidence data are available from African urban slums. We investigated the epidemiology of shigellosis and drug susceptibility patterns within a densely populated urban settlement in Nairobi, Kenya through population-based surveillance. METHODS: Surveillance participants were interviewed in their homes every 2 weeks by community interviewers. Participants also had free access to a designated study clinic in the surveillance area where stool specimens were collected from patients with diarrhea (≥3 loose stools within 24 hours) or dysentery (≥1 stool with visible blood during previous 24 hours). We adjusted crude incidence rates for participants meeting stool collection criteria at household visits who reported visiting another clinic. RESULTS: Shigella species were isolated from 262 (24%) of 1,096 stool specimens [corrected]. The overall adjusted incidence rate was 408/100,000 person years of observation (PYO) with highest rates among adults 34-49 years old (1,575/100,000 PYO). Isolates were: Shigella flexneri (64%), S. dysenteriae (11%), S. sonnei (9%), and S. boydii (5%). Over 90% of all Shigella isolates were resistant to trimethoprim-sulfamethoxazole and sulfisoxazole. Additional resistance included nalidixic acid (3%), ciprofloxacin (1%) and ceftriaxone (1%). CONCLUSION: More than 1 of every 200 persons experience shigellosis each year in this Kenyan urban slum, yielding rates similar to those in some Asian countries. Provision of safe drinking water, improved sanitation, and hygiene in urban slums are needed to reduce disease burden, in addition to development of effective Shigella vaccines

Minimising antibiotic resistance to Staphylococcus aureus in developing countries

(East African Medical Journal: 2002 79 (11): 574-579

Impact of single session post-partum counselling of HIV infected women on their subsequent reproductive behaviour

During an ongoing study investigating the impact of maternal HIV infection on pregnancy outcome at a large maternity hospital in Nairobi, Kenya, asymptomatic HIV positive women who had recently delivered were informed of their HIV sero-status and counselled by a trained nurse regarding contraception and reproductive behaviour in a single session. Both HIV infected women and a comparison group of uninfected women matched for pregnancy outcome were followed up after an interval of one year. Contraceptive use, condom use and pregnancy rates were similar in both groups. Only 37% of HIV infected women had informed their partners of their sero-status. The single session of counselling for the HIV positive women did not seem to influence decisions on subsequent condom use or reproductive behaviour. More intensive approaches to counselling need to be developed and evaluated, but may be difficult to implement in the busy maternity and antenatal clinics commonly found in developing countries

Epidemiology of acute respiratory tract infections among young children in Kenya

The epidemiology of acute respiratory tract infection (ARI) was investigated in a rural community 80 km north of Nairobi, Kenya. This research was conducted prospectively on 250 families with 470 children \u3c5 years of age who were contacted every 8 days during the 3-year study. The yearly incidence of respiratory tract infections decreased from 5.2 to 3.4 during the\u3estudy; \u3c5% of these infections involved the lower respiratory tract. The incidence was inversely related to age, and the illnesses were generally mild and brief in length. Fifteen children died during the study period. The precise causes of death are unknown, but respiratory infections possibly played a role in most cases. This study emphasizes the importance of determining the risk factors responsible for unusually severe morbidity and high mortality in children with ARI in developing countries