Biomedical subjects

David C W Mabey

Publications and source records attributed to David C W Mabey.

5 recordsLinked to original sources

PubMed2003

Strategies for control of trachoma: observational study with quantitative PCR.

BACKGROUND: Antibiotics are an important part of WHO's strategy to eliminate trachoma as a blinding disease by 2020. At present, who needs to be treated is unclear. We aimed to establish the burden of ocular Chlamydia trachomatis in three trachoma-endemic communities in Tanzania and The Gambia with real-time quantitative PCR. METHODS: Conjunctival swabs were obtained at examination from 3146 individuals. Swabs were first tested by the qualitative Amplicor PCR, which is known to be highly sensitive. In positive samples, the number of copies of omp1 (a single-copy C trachomatis gene) was measured by quantitative PCR. FINDINGS: Children had the highest ocular loads of C trachomatis, although the amount of pooling in young age groups was less striking at the site with the lowest trachoma frequency. Individuals with intense inflammatory trachoma had higher loads than did those with other conjunctival signs. At the site with the highest prevalence of trachoma, 48 of 93 (52%) individuals with conjunctival scarring but no sign of active disease were positive for ocular chlamydiae. INTERPRETATION: Children younger than 10 years old, and those with intense inflammatory trachoma, probably represent the major source of ocular C trachomatis infection in endemic communities. Success of antibiotic distribution programmes could depend on these groups receiving effective treatment.

Adolescent↗

PubMed2003

Trachoma.

Trachoma is the most common infectious cause of blindness. It is caused by ocular serovars of Chlamydia trachomatis. Transmission is favoured in poor communities, where crowding is common and access to water and sanitation inadequate. Repeated reinfection over many years causes dense scarring of the upper eyelid. The resultant inversion of the lashes abrades the eyeball, and the abrasion leads to corneal opacification and visual impairment. The host immune response is probably at least partly the cause of this process. The "SAFE" strategy is used for the control of trachoma: surgery for in-turned lashes, antibiotics for active disease, facial cleanliness, and environmental improvement. The demonstration that a single oral dose of the antibiotic azithromycin is as effective as 6 weeks of topical tetracycline was an important advance in trachoma control. By means of the SAFE strategy, WHO and its partners aim to eliminate trachoma as a public-health problem by the year 2020.

Chlamydia trachomatis↗

PubMed2003

Impact of azithromycin administration for trachoma control on the carriage of antibiotic-resistant Streptococcus pneumoniae.

Community distribution of azithromycin has an important role to play in trachoma control. Previous studies have suggested that this may increase the prevalence of macrolide-resistant Streptococcus pneumoniae. S. pneumoniae was isolated from children under 7 years of age in Rombo District, northern Tanzania, before and 2 and 6 months after community-wide administration of azithromycin. Overall carriage rates were 11, 12, and 7%, respectively. Only one macrolide-resistant isolate carrying the mef gene was obtained 6 months after azithromycin administration. This contrasted with cotrimoxazole and penicillin resistance, both of which were common (cotrimoxazole resistance, 42, 43, and 47%, and penicillin resistance, 21, 17, and 16% at baseline, 2 months, and 6 months, respectively). There was a significant association between cotrimoxazole and penicillin resistance (P < 0.0001, Fisher's exact). These data suggest that in communities where macrolide resistance is rare, azithromycin distribution for trachoma control is unlikely to increase the prevalence of resistant organisms.

Anti-Bacterial Agents↗

PubMed2003

Genital human papillomavirus genotypes in northwestern Tanzania.

Using MY09-MY11 PCR and human papillomavirus (HPV) typing by reverse blot hybridization, we found a 34% cervical HPV prevalence among 561 pregnant women in Tanzania. One hundred three of 123 women (84%) with typeable samples harbored high-risk oncogenic strains. HPV type 16 (HPV-16) was the most prevalent subtype (18%) among HPV-infected women and among women with cervical neoplasia (3 of 19). A multivalent vaccine for HPV-16, -18, -31, -33, and -35 would be necessary to prevent 50% of the neoplasia in this population.

Adolescent↗

PubMed2003

Which members of a community need antibiotics to control trachoma? Conjunctival Chlamydia trachomatis infection load in Gambian villages.

PURPOSE: Trachoma is the leading cause of infectious blindness worldwide. Control strategies target antibiotic therapy to individuals likely to be infected with Chlamydia trachomatis on the basis of clinical signs. However, many studies have found chlamydial infection in the absence of clinical disease. It has been unclear whether such individuals represent a significant reservoir of infection. In the current study, a quantitative polymerase chain reaction (PCR) assay was used to investigate the distribution and determinants of chlamydial infection load in an endemic community, and the findings were used to evaluate the potential effectiveness of different control strategies. METHODS: Members of a trachoma-endemic community (n = 1319) in a rural area of The Gambia were examined for signs of disease, and tarsal conjunctival swab samples were collected. C. trachomatis was initially detected by qualitative PCR. The load of infection was then estimated by real-time quantitative PCR. RESULTS: Chlamydial infection was detected in 7.2% of the population. The distribution of infection load was skewed, with a few individuals having high loads. Only 24% of infected individuals had signs of active trachoma. Infection loads were higher in those with clinically active disease and were highest among those with severe inflammatory trachoma. High infection loads were associated with having no accessible latrine and living with a person with active disease. CONCLUSIONS: In this low-prevalence setting, infected individuals without signs of active trachoma constitute a significant reservoir of infection. Treatment of a defined unit of people who live with someone with clinically active trachoma would effectively target antibiotic treatment to infected people without signs of disease.

Adolescent↗