Health laboratories in the Tanga region of Tanzania: the quality of diagnostic services for malaria and other communicable diseases.

Although critical for good case management and the monitoring of health interventions, the health-laboratory services in sub-Saharan Africa are grossly compromised by poor infrastructures and a lack of trained personnel, essential reagents and other supplies. The availability and quality of diagnostic services in 37 health laboratories in three districts of the Tanga region of Tanzania have recently been assessed. The results of the survey, which involved interviews with health workers, observations and a documentary review, revealed that malaria accounted for >50% of admissions and out-patient visits. Most (92%) of the laboratories were carrying out malaria diagnosis and 89% were measuring haemoglobin concentrations but only one (3%) was conducting culture and sensitivity tests, and those only on urine and pus samples. Only 14 (17%) of the 84 people found working in the visited laboratories were laboratory technologists with a diploma certificate or higher qualification. Sixteen (43%) of the study laboratories each had five or fewer types of equipment and only seven (19%) had more than 11 types each. Although 11 (30%) of the laboratories reported that they conducted internal quality control, none had standard operating procedures (SOP) on display or evidence of such quality assurance. Although malaria was the main health problem, diagnostic services for malaria and other diseases were inadequate and of poor quality because of the limited human resources, poor equipment and shortage of supplies. If the health services in Tanga are not to be overwhelmed by the progressively increasing burden of HIV/AIDS, malaria, tuberculosis and other emerging and re-emerging diseases, more funding and appropriate policies to improve the availability and quality of the area's diagnostic services will clearly be required.

Diversity of Plasmodium falciparum clones infecting children living in a holoendemic area in north-eastern Tanzania.

The diversity of Plasmodium falciparum clones and their role in progression from asymptomatic to symptomatic condition in children have been investigated. Attempts to identify whether particular parasite genotypes were associated with the development of clinical symptoms have been made. A cohort of 34 initially asymptomatic parasitaemic children aged 1-5 years were followed daily for 31 days. Clinical examinations were made each day for signs and symptoms of clinical malaria, followed by parasitological investigation. Nineteen children developed symptoms suggestive of clinical malaria during this period. Daily blood parasite samples from 13 children who developed clinical malaria symptoms and 7 who remained asymptomatic were genotyped by PCR-amplification of the polymorphic regions of the merozoite surface proteins 1 and 2 (MSP1 and MSP2) and the glutamate rich protein (GLURP) genes. Infections were found to be highly complex in both groups of children. Every isolate examined from both groups had a mixture of parasite clones. Daily changes were observed in both parasite density and genotypic pattern. The mean number of genotypes per individual was estimated at 4.9 and 2.7 for asymptomatic and symptomatic groups of children, respectively. Analysis of allele frequency distributions showed that these differed significantly for the MSP1 locus only.

Distinguishing Plasmodium falciparum treatment failures from re-infections by using polymerase chain reaction genotyping in a holoendemic area in northeastern Tanzania.

An in vivo drug sensitivity study was conducted in Magoda village in northeastern Tanzania to evaluate the usefulness of polymerase chain reaction (PCR)-based genotyping of Plasmodium falciparum parasites to distinguish between re-infection and treatment failure. The study tested P. falciparum susceptibility to a combination of sulfadoxine/pyrimethamine (Fansidar; F. Hoffmann La Roche, Basel, Switzerland). Blood samples were collected before treatment and on days 7, 14, or 28 post-treatment in 51 asymptomatic children, of which 26 could not clear parasitemia within seven days post-treatment. Among the remaining 25 children who had no detectable parasites on day 7, only five remained parasite negative up to day 28. Primary and recrudescent P. falciparum parasites were analyzed by PCR using family specific primers for merozoite surface protein-1 (MSP-1), MSP-2, and glutamate-rich protein (GLURP). All samples contained multiple P. falciparum infections. For all children with recrudescent P. falciparum, common alleles were detected in both the primary and recrudescent samples. However, in no child were the exact same alleles detected in both samples, indicating that probably at least some of the recrudescing parasites originated from new infections. The study demonstrates the general usefulness of PCR genotyping technique in distinguishing re-infections from true recrudescences following therapeutic drug treatment.

Sampling gravid Culex quinquefasciatus (Diptera: Culicidae) in Tanzania with traps baited with synthetic oviposition pheromone and grass infusions.

The effectiveness of traps baited with (5R,6S)-6-acetoxy-5-hexadecanolide (the synthetic oviposition pheromone) and grass infusions in sampling a population of gravid Culex quinquefasciatus Say was conducted in Muheza, Northeast Tanzania. A counterflow geometry (CFG) trap baited with pheromone and set outdoors, adjacent to a pit latrine building, collected more gravid Cx. quinquefasciatus than a CDC trap baited with pheromone and operated without light. Inside pit latrine buildings, significantly more gravid Cx. quinquefasciatus were collected in a CFG trap-baited with pheromone or grass infusion than in traps baited with tap water. CFG traps baited with either grass infusion or pheromone and set outdoors, away from known breeding sites, caught significantly more gravid Cx. quinquefasciatus than traps baited with tap water. CFG traps baited with pheromone + grass infusion caught significantly more gravid Cx. quinquefasciatus than CFG traps baited with either grass infusion or pheromone. In both cases, the proportion of gravid mosquitoes increased as traps were moved away from a natural emergence site. More gravid Cx. quinquefasciatus were collected in a pheromone-baited CFG trap than were egg rafts deposited in a jar with pheromone-treated water. It is concluded that CFG traps baited with oviposition attractants can be used effectively to sample gravid Cx. quinquefasciatus.