Results from the first 30 months of national sentinel surveillance for influenza in Tanzania, 2008-2010.

Limited data exist on the burden of influenza in developing countries. In 2008, in order to better understand the epidemiology of influenza virus infection in Tanzania, the Tanzanian Ministry of Health and Social Welfare created a sentinel surveillance system for influenza. At 5 hospitals across the country, patients with influenza-like illness (ILI) and severe acute respiratory illness (SARI) had oropharyngeal and nasopharyngeal samples collected. At the National Influenza Center in Dar es Salaam, specimens were tested for influenza using real-time polymerase chain reaction tests. From May 2008 through November 2010, a total of 1794 samples were collected from 5 sentinel sites, of which 61% were from patients with ILI and 39% were from patients with SARI. Of all ILI and SARI samples, 8.0% were positive for influenza; 6.9% yielded influenza A virus, and 1.1% yielded influenza B virus. Most influenza A virus was subtype H3, which circulated in nearly every month of 2010. The proportion of influenza-positive cases was similar among ILI (8.5%) and SARI (7.3%) patients (P = .39). In multivariate logistic regression, influenza-positive SARI cases were more likely than influenza-negative SARI cases to have had rhonchi (adjusted OR [aOR], 2.31; 95% confidence interval [CI], 1.14-4.67), nasal discharge (aOR, 4.57; 95% CI, 1.30-16.10), and stridor (aOR, 2.63; 95% CI, 1.17-5.90). Influenza-positive ILI patients had a longer duration of fever on presentation, compared with influenza-negative ILI patients (median, 4 vs 3 days; P = .004). Otherwise, there was no difference in signs or symptoms among influenza-positive and influenza-negative ILI patients. During 2.5 years of surveillance for influenza at 5 geographically disbursed sites in Tanzania, we found that influenza circulated year-round. Surveillance should continue in order to fully understand the seasonality and epidemiology of influenza in Tanzania.

Antituberculosis drug resistance and anonymous HIV surveillance in tuberculosis patients in Botswana, 2002.

Two surveys undertaken in Botswana in the 1990s have recorded low rates of antituberculosis drug resistance, despite a three-fold rise in tuberculosis since 1989. We undertook a third survey to determine both trends since 1995 and HIV prevalence in tuberculosis patients in Botswana. Sputum specimens were obtained from patients nationwide in 2002 who also underwent anonymous, rapid HIV testing by use of Oraquick. Of 2200 sputum smear-positive patients and 219 previously treated patients with suspected recurrent tuberculosis, 1457 (60%) were infected with HIV. Resistance to at least one drug in new patients rose from 16 (3.7%) isolates in 1995 to 123 (10.4%; p<0.0001) in 2002. Interventions for tuberculosis control are urgently needed in Botswana to prevent further emergence of drug resistance.

Control of anti-tuberculosis drug resistance in Botswana.

SETTING: Botswana, where in 2000 the prevalence of human immunodeficiency virus (HIV) infection among adults was 38%, and the tuberculosis (TB) rate was 591/100,000. A 1995-1996 survey demonstrated low levels of anti-tuberculosis drug resistance. OBJECTIVE: Because TB drug resistance may increase rapidly in HIV-infected populations, a second survey was undertaken in 1999 to determine any increase in anti-tuberculosis drug resistance. DESIGN: Sputum specimens positive for acid-fast bacilli from patients without prior TB treatment (new patients), and all sputum specimens from patients reporting prior TB treatment (retreatment patients) were collected nationwide. Specimens were cultured for Mycobacterium tuberculosis and tested for resistance to isoniazid, rifampicin, ethambutol, and streptomycin. RESULTS: From January to May 1999, 783 patients were consecutively enrolled from all districts. Of these, 483 (61.7%) were male, the median age was 33 years, and 82% were new patients. Drug resistance occurred in 6.3% of new patients (95 % confidence interval [CI] 4.6-8.6) and 22.8% of retreatment patients (95% CI 16.5-30.1). Resistance to at least isoniazid and rifampicin was found in 0.5% of new (95% CI 0.1-1.3) and 9.0% of retreatment patients (95% CI 5.1-14.5). CONCLUSION: Anti-tuberculosis drug resistance remains relatively low in Botswana, probably as a result of a well-functioning TB program. Periodic surveys will be essential to adequately determine any significant trend.

Molecular and conventional epidemiology of Mycobacterium tuberculosis in Botswana: a population-based prospective study of 301 pulmonary tuberculosis patients.

Little is known about patterns of tuberculosis (TB) transmission among populations in developing countries with high rates of TB and human immunodeficiency virus (HIV) infection. To examine patterns of TB transmission in such a setting, we performed a population-based DNA fingerprinting study among TB patients in Botswana. Between January 1997 and July 1998, TB patients from four communities in Botswana were interviewed and offered HIV testing. Their Mycobacterium tuberculosis isolates underwent DNA fingerprinting using IS6110 restriction fragment length polymorphism, and those with matching fingerprints were reinterviewed. DNA fingerprints with >5 bands were considered clustered if they were either identical or differed by at most one band, while DNA fingerprints with < or =5 bands were considered clustered only if they were identical. TB isolates of 125 (42%) of the 301 patients with completed interviews and DNA fingerprints fell into 20 different clusters of 2 to 16 patients. HIV status was not associated with clustering. Prior imprisonment was the only statistically significant risk factor for clustering (risk ratio, 1.5; 95% confidence interval, 1.1 to 2.0). In three communities where the majority of eligible patients were enrolled, 26 (11%) of 243 patients overall and 26 (25%) of 104 clustered patients shared both a DNA fingerprint and strong antecedent epidemiologic link. Most of the increasing TB burden in Botswana may be attributable to reactivation of latent infection, but steps should be taken to control ongoing transmission in congregate settings. DNA fingerprinting helps determine loci of TB transmission in the community.

Low levels of drug resistance amidst rapidly increasing tuberculosis and human immunodeficiency virus co-epidemics in Botswana.

SETTING: Botswana, southern Africa, where the tuberculosis (TB) case rate increased by 120% from 1989 to 1996 in spite of a decade of implementation of the directly observed therapy, short-course (DOTS) strategy. OBJECTIVE: To determine prevalence of and risk factors for drug-resistant tuberculosis in an epidemic setting. DESIGN: Systematic national random survey of newly diagnosed pulmonary TB and all patients with TB requiring retreatment during 1995-1996. Interviews were conducted, human immunodeficiency virus (HIV) testing was offered, and drug susceptibility testing was performed for isoniazid, rifampicin, streptomycin and ethambutol. RESULTS: Resistance to at least one drug was identified in 16 (3.7%) new cases and 18 (14.9%) retreatment cases. One (0.2%) new and seven (5.8%) retreatment cases had resistance to at least both isoniazid and rifampicin (multidrug-resistant TB). Retreatment cases with multidrug-resistant TB were significantly more likely to have worked in the mines in South Africa than were cases with fully susceptible isolates (6/7 [85.7%] versus 32/ 103 [31.1%], odds ratio 13.3, 95% confidence interval 1.5-311.0, P = 0.007). Of 240 patients tested for HIV, 117 (48.8%) were positive; prevalence was similar among new and retreatment cases, and was not a risk factor for drug resistance in either group. CONCLUSION: During the HIV and TB co-epidemics in sub-Saharan Africa, DOTS may help to control drug-resistant TB. However, the TB case rate can be expected to continue to climb in spite of the implementation of the DOTS strategy.