Surveillance of drug-resistant tuberculosis and molecular evaluation of transmission of resistant strains in refugee and non-refugee populations in North-Eastern Kenya.

SETTING: Three refugee camp complex clinics and an adjacent non-refugee treatment centre in North-Eastern Kenya. OBJECTIVES: To use conventional and molecular epidemiology tools to determine: 1) the prevalence of drug resistance in newly diagnosed patients with smear-positive pulmonary tuberculosis in refugee and non-refugee populations; 2) risk factors for resistance in the two populations; and 3) whether IS6110 restriction fragment length polymorphism (RFLP) and spoligotyping showed similarities in DNA fingerprinting patterns of drug-resistant isolates that could infer transmission within and between the two populations. RESULTS: Of 241 isolates from the camps, 44 (18.3%) were resistant to one or more drugs, seven of which (2.9%) were multidrug-resistant TB (MDR-TB). Of 88 isolates from the non-refugees, five (5.7%) were resistant to one or more drugs without MDR-TB. Drug resistance was higher in the camps than in the non-refugee population (OR = 3.7; 95%CI 1.42-9.68; P < 0.007). Resistance was significantly higher in one camp compared with the other two, despite a comparable ethnic distribution. Unusually, females were more associated with drug resistance than their male counterparts in both populations (OR = 2.3; 95%CI 1.2-4.8; P = 0.008). There was evidence of transmission of streptomycin-resistant strains in the refugee population. DNA fingerprints of resistant strains from the non-refugee population were unique and different from those in the refugee camps. CONCLUSION: The observed high levels of drug resistance and MDR-TB, combined with evidence of transmission of strains resistant to streptomycin in the refugee population, suggest a need for strengthened TB control programmes in settings with a high risk of developing drug-resistant strains.

National tuberculin survey of Kenya, 1986-1990.

SETTING: The first tuberculin survey conducted in Kenya by the World Health Organisation in 1958-1959 found an annual risk of tuberculosis infection (ARTI) of 2.5%. OBJECTIVE: To estimate the ARTI and its trend in recent years and to compare the estimated incidence rates with the notification rates. DESIGN: A tuberculin survey was held in 12 randomly selected districts in the period 1986-1990. Tuberculin testing with 2TU PPD RT 23 + Tween 80 was performed in 40,365 primary schoolchildren aged 6-13. RESULTS: Of 14,984 non BCG-vaccinated children, 1,380 (9.2%) had indurations of > or = 10 mm. Double testing with PPD RT 23 and PPD-scrofulaceum in 980 non BCG-vaccinated children revealed a high level of infections due to mycobacteria other than tuberculosis (MOTT). Therefore, the prevalence of tuberculous infection was based on the sum of 50% of the indurations of 17 mm and all indurations of 18 mm or more multiplied by two. The prevalence of tuberculous infection in schoolchildren aged on average 8.4 years, 'weighted' for the population size according to the provisional results of the 1989 census, was calculated at 5.5%. The corresponding ARTI is 0.6%. CONCLUSION: The ARTI has declined by an average 4.6% per year. The tuberculosis problem differs from one area to the next, with the highest prevalences of infection on the coast and in Eastern Kenya, and the lowest in Western Kenya. Although the average ratio of observed and estimated incidences indicate that 70% of incident cases are notified, considerable inter-district variations are observed.

Effect of non-tuberculous Mycobacteria infection on tuberculin results among primary school children in Kenya.

Few tuberculosis studies carried out in Kenya since 1948 have reported on the variations of the occurrence and geographical distributions of non-tuberculous Mycobacteria infection. They have however not been able to clearly relate infection outcome to the use of tuberculin tests as epidemiologic and clinical tool. The present survey, conducted by Kenya Medical Research Institute in collaboration with the International Union Against Tuberculosis and Lung Diseases between 1986 and 1990 among school children aged 6-13 years in 18 randomly selected districts, investigated the following: the prevalence of sensitivity to tuberculin PPD RT 23 and PPD scrofulaceum RS 95 sensitin; geographic distribution of the reactions from the tests and; the influence of non-tuberculous Mycobacteria on the tuberculin results. The WHO cluster sampling procedures were used to select 30 schools in each of the 18 districts. Each child was tested with an intradermal dose of 2 TU of PPD RT 23 with Tween 80 (PPD RT 23) on the right hand and 2 TU of PPD Scrofulaceum RS 95 sensitin with tween 80 (PPD RS 95) on the left hand. The results were read after 72 hours of testing. A total of 1015 BCG scar negative children was included in the survey. Of these, 981 were tested and read. Over 47% of the children did not react to both antigens while 6.1% and 22.7% reacted to human type tuberculin and environmental sensitin respectively. There was cross reaction between the two tests in 23.8% of the children from low altitude area who had more and larger reaction to the tests than the middle and higher altitude regions of the country.(ABSTRACT TRUNCATED AT 250 WORDS)

A study of the use of maternity and child welfare clinics in case-finding for pulmonary tuberculosis in Kenya.

This investigation is the seventh in a series of case-finding studies in Kenya. It explores the potential value of questioning mothers attending maternity and child welfare (M & CW) clinics to identify tuberculosis suspects (individuals aged 6 years or more with a cough for 1 month or more or hemoptysis) living in their households. The study was carried out in all the eight M & CW clinics in two divisions (populations 86,000 and 112,000) of two different districts. The mothers were asked to give a standard letter, which explained the possible importance of a chronic cough, to each suspect they identified and invited the suspect to attend the district hospital chest clinic. Each suspect attending the clinic was entered in a special register and two sputum specimens were collected. For those who failed to attend, the specimens were collected at a home visit. Of the total of 342 suspects living in the two study areas who were registered at the M & CW clinics during 1 year, 261 were identified by the mothers but 19 denied having received the standard letter. The remaining 81 had not been identified by mothers but had attended the M & CW clinics on their own initiative. Of the 242 suspects who received the letter, 89 (39%) attended the hospital chest clinic, 74% within a week of the letter being issued from the M & CW clinic. The main reasons given for not attending the hospital chest clinic by the remaining suspects were financial or because their cough had improved or disappeared. Sputum was collected from 238 suspects and examined bacteriologically: in six (2.5%) it was positive for tubercle bacilli on smear and culture and in a further two (0.8%) the sputum was positive on culture only. Of those attending the hospital chest clinic 2.9% were smear- and culture-positive and 4.7% were culture positive. This method of case-finding has yielded disappointing results, for only 4% of the estimated annual incidence of smear-positive cases was detected.

Studies of case-finding for pulmonary tuberculosis in outpatients at 4 district hospitals in Kenya.

This investigation is the sixth in a series of case-finding studies in Kenya. It explores the potential for case-finding by the identification of tuberculosis suspects (individuals with a cough for 1 month or more) through careful screening of general outpatients attending 4 district hospitals for the first time. Of 2299 suspects identified among 87 845 new outpatients attending the hospitals, 4.7% had culture-positive pulmonary tuberculosis, 3.6% having sputum positive on smear as well. In the 3 hospitals with radiographic facilities, 1.3% of suspects (whose sputum was negative on culture) were considered on review of their clinical history and chest radiograph by an independent assessor to have radiographically active tuberculous lesions and a further 2.5% to have inactive lesions. The proportion of bacteriologically positive cases per 1000 of the general population aged 6 years or more decreased as the distance of their homes from the hospital increased (P less than 0.001 for the trend). However, the proportion of cases per 1000 of the suspects identified increased as the distance of their homes from the hospital increased (P less than 0.001 for the trend). History of cough for between 1 and 12 months was the most useful factor for the identification of cases of tuberculosis among the suspects, and would have identified 92% of the smear-positive cases from the examination of 70% of the suspects; a history of weight loss identified 84% of the smear-positive cases from the examination of 64% of the suspects. A history of weight loss and/or a history of cough for between 1 and 12 months would have detected all the smear-positive cases from the examination of 89% of the suspects. The proportion of bacteriologically positive cases in the younger suspects aged 9-32 years (who had been eligible for a mass BCG campaign) was greater among the non-vaccinated than among the vaccinated suspects, 4.9% and 2.3% respectively (P=0.04), implying protection from vaccination of the order of 50%.

Study of case-finding for pulmonary tuberculosis in outpatients complaining of a chronic cough at a district hospital in Kenya.

This investigation is the fifth in a series of case-finding studies in Kenya. It explores the potential for case-finding by the identification of persons with suspected tuberculosis (persons with a cough for 1 month or more) through careful screening of general outpatients attending a district hospital. Of 601 suspects identified among 20,756 new outpatients attending hospital during a period of 11 wk, 5.6% were considered by an independent assessor to have active pulmonary tuberculosis (2.2% with sputum positive on both smear and culture, 1.2% on culture only, and 2.2% negative sputum but radiographically active lesions). A further 2.0% were considered to have inactive tuberculosis. This method of case-finding appears to be uniformly effective within a radius of approximately 9 miles of the hospital, becoming less effective outside this range. There were certain important diagnostic pointers. There was an excess of tuberculosis cases in males, in those with weight loss, in those with a history of cough of less than a year, in those with a history of hemoptysis, and in those 35 yr of age or older. This investigation provides additional support to our previous studies, which demonstrated serious problems of case-finding in the peripheral health units and suggests that unless the infrastructure of primary health care at the periphery can be improved, the policy should be to diagnose tuberculosis in the district hospital and to operate a simple referral system for persons with suspected tuberculosis from the periphery.