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Factors associated with carcinoma of the oesophagus at Mulago Hospital, Uganda
No full textBackground: In Uganda, as in many other parts of the world cancer of the oesophagus (CAE) is on the rise. Squamous cell carcinoma
and adenocarcinoma are the common subtypes. Risk factors for this cancer have been identified but not studied systematically in
Uganda. Identification of these factors would enable establishment of preventive measures.
Objective To determine the prevalence, histological features and associated factors for CAE among patients referred to the endoscopic
unit of Mulago hospital, Kampala, Uganda.
Methods: We performed a 1-year cross-sectional study in 2004 and 2005 of all patients presenting for oesophageal-gastro-duodenoscopy
(EGD) at Mulago Hospital. Demographic characteristics, behavioural practices, endoscopy findings and histology results where
biopsies were performed were collected using a study tool. Data analysis was done using STATA 8® statistical package
Results: Two hundred nineteen patients were enrolled in the study, three were excluded because they could not tolerate the
endoscopy procedure. Fifty five (19%) of the 287 had histologically proven CAE. Squamous cell carcinoma was found in 100% of
tumours of the upper third, 91% middle third, and 73% lower third of the oesophagus. Four patients had a histological diagnosis of
adenocarcinoma of the oesophagus. Factors that were associated with CAE included age (OR 1.63, CI 1.34-1.98, p value <0.001),
smoking (OR 3.63, CI 1.82-7.23, p value <0.001) and gender (OR 2.17, CI 1.07-4.41, p value 0.032).
Conclusion: Many patients referred for EGD in Uganda had esophageal cancer most of which were.squamous cell type. Smoking,
male gender and older age were risk factors. Preventive measures should target stopping smoking
Failure to detect Plasmodium vivax in west and central Africa by PCR species typing
No full textBackground: Plasmodium vivax is estimated to affect 75 million people annually. It is reportedly
absent, however, from west and central Africa due to the high prevalence of the Duffy negative
phenotype in the indigenous populations. Despite this, non-African travellers consistently return to
their own countries with P. vivax malaria after visiting this region. An attempt was made, therefore,
to detect the presence of P. vivax parasites in blood samples collected from the indigenous
populations of west and central Africa.
Methods: Parasite species typing (for all four human malaria parasites) was carried out by PCR on
2,588 blood samples collected from individuals from nine African malaria-endemic countries.
Results: Most infections (98.5%) were Plasmodium falciparum, Plasmodium malariae was identified
in 8.5% of all infections, and Plasmodium ovale in 3.9%. The prevalence of both parasites varied
greatly by country. Only one case of P. vivax was detected from Sao Tome, an island off the west
coast of Africa, confirming the scarcity of this parasite in Africa.
Conclusion: The prevalence of P. vivax in local populations in sub-Saharan Africa is very low,
despite the frequent identification of this parasite in non-African travellers
Evolutionary history of Trypanosoma cruzi according to antigen genes
No full textTrypanosoma cruzi, the agent of Chagas disease is associated with a very high clinical and epidemiological pleomorphism.
This might be better understood through studies on the evolutionary history of the parasite. We explored here the value of
antigen genes for the understanding of the evolution within T. cruzi. We selected 11 genes and 12 loci associated with
different functions and considered to be involved in host-parasite interaction (cell adhesion, infection, molecular mimicry).
The polymorphism of the respective genes in a sample representative of the diversity of T. cruzi was screened by
PCR-RFLP and evolutionary relationships were inferred by phenetic analysis. Our results support the classification of
T. cruzi in 2 major lineages and 6 discrete typing units (DTUs). The topology of the PCR-RFLP tree was the one that
better fitted with the epidemiological features of the different DTUs: (i) lineage I, being encountered in sylvatic as well as
domestic transmission cycles, (ii) IIa/c being associated with a sylvatic transmission cycle and (iii) IIb/d/e being associated
with a domestic transmission cycle. Our study also supported the hypothesis that the evolutionary history of T. cruzi has
been shaped by a series of hybridization events in the framework of a predominant clonal evolution pattern
Molecular typing of the actin gene of Trichomonas vaginalis isolates by PCR-restriction fragment length polymorphism
No full textThe definitive version is available at www3.interscience.wiley.comHuman trichomoniasis, caused by the protozoan Trichomonas vaginalis, is a highly prevalent sexually transmitted infection. However, little is known about the degree of strain variability of T. vaginalis. A reliable classification method for T. vaginalis strains would be a useful tool in the study of the epidemiology, pathogenesis and transmission of T. vaginalis. A PCR-restriction fragment length polymorphism typing method was designed and evaluated using T. vaginalis isolates obtained after culture of vaginal specimens collected in the Democratic Republic of Congo and in Zambia. The variation of the actin gene of T. vaginalis was determined for three ATCC reference strains and 151 T. vaginalis isolates. Eight different types were identified, on the basis of the digestion patterns of the amplified actin gene, with each of the restriction enzymes HindII, MseI and RsaI. It was determined that the ATCC reference strains 30001, 30240 and 50141 were of actin genotypes G, H and E, respectively. The actin genotype type E was more common in the Democratic Republic of Congo, whereas type G was the commonest type in Zambia. Translation of the nucleotide sequence showed up to three amino acid substitutions. We developed a reproducible, sensitive and specific typing method for T. vaginalis, and were able to distinguish at least eight T. vaginalis actin genotypes. Further studies are needed to evaluate the method using clinical specimens and to determine the utility of the typing method for the genotypic characterization of T. vaginalis
Evaluating the use of packed cell volume as an indicator of trypanosomal infections in cattle in eastern Zambia
No full textIn this study, packed cell volume-values (PCV) are evaluated as indicator of trypanosomiasis infections in cattle. A total of 734 blood samples were collected in 11 different sampling sites in eastern Zambia: 84 calves (3 years). All samples were subjected to three diagnostic tests: parasitological examination using the buffy coat method, PCR/RFLP and PCV determination. The results were compared and analysed in a Bayesian model, which allowed the estimation of the infection prevalence and the respective test sensitivities and specificities. The presence of a trypanosomal infection significantly reduced the PCV, independently of the age and sex of the infected animal. The estimated prevalence of trypanosomal infections in the study area was 34% (95% credibility interval: 30-38%). While the specificity of both the parasitological and the PCR/RFLP tests were set to 1, the parasitological diagnosis had a low sensitivity (37%) compared to the PCR/RFLP (96%). When using a cut-off value of 24, the PCV had a high specificity (98%) but a rather low sensitivity (53%) for identifying trypanosomiasis infections. Using 26% as a cut-off increased the sensitivity to 76% without much affecting the specificity (94%). A parallel combination of the parasitological diagnosis and the PCV improved the diagnostic sensitivity (74% and 89% for PCV cut-off values of 24% or 26%, respectively) while specificity remained high (98% and 94% for PCV cut-off values of 24% or 26%, respectively). These results suggest that such a combination could advantageously be used for the diagnosis of cattle trypanosomiasis in the field: it is much more sensitive than parasitological examination alone and it is much cheaper than molecular tests. However, the value of this approach depends largely on the determination of an appropriate cut-off value to consider a sample positive, depending on the required test sensitivities and specificities
Role of the laboratory in ensuring global access to ARV treatment for HIV-infected children: consensus statement on the performance of laboratory assays for early infant diagnosis
No full textA two day meeting hosted by the World Health Organization (WHO) and the U.S. Centers for Disease Control and Prevention (CDC) was held in May 2006 in Entebbe, Uganda to review the laboratory performance of virologic molecular methods, particularly the Roche Amplicor DNA PCR version 1.5 assay, in the diagnosis of HIV-1 infection in infants. The meeting was attended by approximately 60 participants from 17 countries. Data on the performance and limitations of the HIV-1 DNA PCR assay from 9 African countries with high-burdens of HIV/AIDS were shared with respect to different settings and HIV- subtypes. A consensus statement on the use of the assay for early infant diagnosis was developed and areas of needed operational research were identified. In addition, consensus was reached on the usefulness of dried blood spot (DBS) specimens in childhood as a means for ensuring greater accessibility to serologic and virologic HIV testing for the paediatric population
Concurrent infections of Fasciola, Schistosoma and Amphistomum spp. in cattle from Kafue and Zambezi river basins of Zambia
No full textThis study investigated interactions among Fasciola gigantica, Schistosoma spp. and Amphistomum spp. concurrent natural infections in Zambian cattle, based on egg and worm counts. In the abattoir 315 cattle were screened for worms of F. gigantica in the liver, Schistosoma spp. in mesenteric veins and/or Amphistomum spp. in the rumen. One hundred and thirty-three (42.2%) of the abattoir-examined cattle harboured one, two or all three trematodes. Of 133 cattle, 50 were randomly selected for worm and egg counts. The mean numbers (+/- SD) of Amphistomum, Schistosoma and Fasciola were 622.08 (+/- 97.87), 33.68 (+/- 7.44) and 19.46 (+/- 4.58), respectively. A total of 32% harboured all the three trematodes, 66% had F. gigantica and Amphistomum spp. infections, 52% had Schistosoma spp. and Amphistomum spp. infections while 32% had F. gigantica and Schistosoma infections. A positive correlation (P = 0.014) was found between F. gigantica and Amphistomum worm burdens. There were no correlations between Amphistomum and Schistosoma worm burdens and between F. gigantica and Schistosoma worm burdens. It may be concluded that there is no significant cross-protection among these trematodes in cattle in endemic areas
A significant increase in kdr in Anopheles gambiae is associated with an intensive vector control intervention in Burundi highlands
No full textThe definitive version is available at www3.interscience.wiley.comOBJECTIVES AND METHODS: In Burundi, the occurrence of the knock down resistance (kdr) mutation in Anopheles gambiae sensu lato (s.l.) was determined for six consecutive years within the framework of a vector control programme. Findings were also linked with the insecticide resistance status observed with bioassay in An. gambiae s.l. and An. funestus. RESULTS: The proportion of An. gambiae s.l. carrying the East Leu-Ser kdr mutation was 1% before the spraying intervention in 2002; by 2007 it was 86% in sprayed valleys and 67% in untreated valleys. Multivariate analysis showed that increased risk of carrying the kdr mutation is associated with spraying interventions, location and time. In bioassays conducted between 2005 and 2007 at five sites, An. funestus was susceptible to permethrin, deltamethrin and DDT. Anopheles gambiae s.l. remained susceptible or tolerant to deltamethrin and resistant to DDT and permethrin, but only when kdr allele carriers reached 90% of the population. CONCLUSIONS: The cross-resistance against DDT and permethrin in Karuzi suggests a possible kdr resistance mechanism. Nevertheless, the homozygous resistant genotype alone does not entirely explain the bioassay results, and other mechanisms conferring resistance cannot be ruled out. After exposure to all three insecticides, homozygote individuals for the kdr allele dominate among the surviving An. gambiae s.l. This confirms the potential selection pressure of pyrethroids on kdr mutation. However, the high occurrence of the kdr mutation, even at sites far from the sprayed areas, suggests a selection pressure other than that exerted by the vector control programme
