Transactions of the Royal Society of Tropical Medicine and Hygiene

Editorial Board

2012-02-01

Gastric cancer in Africa: what do we know about incidence and risk factors?

Akwi W. Asombang, Paul Kelly — 2012-02-01

Abstract: Gastric cancer is a major contributor to mortality worldwide, yet its incidence varies widely around the world in a way which our current understanding of aetiology cannot fully explain. Incidence data from Africa are weak, reflecting poor diagnostic resources, but there are firm data on intestinal metaplasia and gastric atrophy which are important steps in the carcinogenesis pathway. The available registry data suggest that incidence is unlikely to be dramatically different from Europe or North America. Helicobacter pylori infection is an important permissive factor in the development of cancer, but H. pylori seroprevalence is high all over Africa and cannot clearly be correlated with cancer. However, there is evidence that specific bacterial virulence genes, particularly vacA and iceA allele1, do contribute to cancer risk. Intestinal metaplasia and gastric atrophy have been the focus of twelve studies and are common in Africa. Epstein-Barr virus, which causes 10% of cancer worldwide, is the focus of only one African study. Work in other continents demonstrates that other risk factors apply only to one or other of the two major histological types, intestinal and diffuse. Diet, smoking, alcohol and salt intake predispose to the intestinal type of cancer, but genetic factors predispose to the diffuse type. There is a pressing need for information on the histological types occurring in Africa, and their associated risk factors. Most urgently, information on dietary predisposition to cancer is required to inform public health policy with respect to the demographic transition (urbanisation and lifestyle changes) which is occurring all over the continent.

Genetic diversity of Ascaris in southwestern Uganda

2012-02-01

Abstract: Despite the common occurrence of ascariasis in southwestern Uganda, helminth control in the region has been limited. To gain further insights into the genetic diversity of Ascaris in this area, a parasitological survey in mothers (n=41) and children (n=74) living in two villages, Habutobere and Musezero, was carried out. Adult Ascaris worms were collected from infected individuals by chemo-expulsion using pyrantel pamoate treatment. Genetic diversity within these worms was assessed by inspection of DNA sequence variation in a mitochondrial marker and length polymorphism at microsatellite loci. Overall prevalence of ascariasis was 42.5% in mothers and 30.4% in their children and a total of 98 worms was examined from 18 hosts. Sequence analysis of a portion of the mitochondrial cytochrome c oxidase subunit 1 gene revealed 19 different haplotypes, 13 of which had not been previously encountered. Microsatellite analysis using eight loci provided evidence for high gene flow between worm populations from the two villages but comparing these worms with others obtained in a prior study on Unguja, Zanzibar, confirmed little genetic exchange and mixing of worm populations between the two areas. By adding to our understanding of the genetic diversity of Ascaris in Africa, this study provides useful information for monitoring changes in parasite population structure in the face of ongoing and future control.

Loss to follow up from isoniazid preventive therapy among adults attending HIV voluntary counseling and testing sites in Uganda

2012-02-01

Summary: Among HIV-infected adults attending non-governmental organization voluntary counseling and testing (VCT) sites in Uganda that provide a nine-month course of isoniazid preventive treatment (IPT), we report on loss to follow-up (LTFU) and its associated risk factors. The design was a retrospective cohort study of program data spanning a three year period (2006–2008). A total of 586 IPT patients were enrolled of whom 335 (57.1%) were females with a mean age of 34 years. Of those starting IPT, 341 (58.1%) were lost to follow-up, 197 (33.6%) completed IPT, 29 (4.9%) were discontinued and 19 (3.2%) died. The return rates at one, three, five and seven months were 78.0% (457), 62.1% (364), 52.9% (310) and 33.6% (197) respectively. Being less than 30 years of age, widowed, separated, or divorced were found to be associated with a higher risk of loss to follow-up. Sudden improvement in retention on IPT was observed between the years 2006 and 2007, although causes of the improvement are poorly understood hence the need for more research.At non-governmental VCT sites in Uganda, six out of ten individuals enrolled on IPT are lost to follow-up and efforts to reduce this attrition including systems strengthening might play a critical role in the success of IPT programs.

Semi-recumbent body position fails to prevent healthcare-associated pneumonia in Vietnamese patients with severe tetanus

2012-02-01

Abstract: Healthcare-associated pneumonia (HCAP) is a common complication in patients with severe tetanus. Nursing tetanus patients in a semi-recumbent body position could reduce the incidence of HCAP. In a randomised controlled trial we compared the occurrence of HCAP in patients with severe tetanus nursed in a semi-recumbent (30°) or supine position. A total of 229 adults and children (aged ≥1 year) with severe tetanus admitted to hospital in Vietnam, were randomly assigned to a supine (n=112) or semi-recumbent (n=117) position. For patients maintaining their assigned positions and in hospital for>48h there was no significant difference between the two groups in the frequency of clinically suspected pneumonia [22/106 (20.8%) vs 26/104 (25.0%); p=0.464], pneumonia rate/1000 intensive care unit days (13.9 vs 14.6; p=0.48) and pneumonia rate/1000 ventilated days (39.2 vs 38.1; p=0.72). Mortality in the supine patients was 11/112 (9.8%) compared with 17/117 (14.5%) in the semi-recumbent patients (p=0.277). The overall complication rate [57/112 (50.9%) vs 76/117 (65.0%); p=0.03] and need for tracheostomy [51/112 (45.5%) vs 69/117 (58.9%); p=0.04) was greater in semi-recumbent patients. Semi-recumbent body positioning did not prevent the occurrence of HCAP in severe tetanus patients. [Clinical Trials.gov Identifier: NCT01331252]

Risk factors for hepatitis C virus infection among Egyptian healthcare workers in a national liver diseases referral centre

2012-02-01

Abstract: Little is known about the prevalence of hepatitis C virus (HCV) among healthcare workers (HCW) in Egypt, where the highest worldwide prevalence of HCV exists. The prevalence of HCV, hepatitis B virus and Schistosoma mansoni antibodies was examined in 842 HCWs at the National Liver Institute in the Nile Delta, where >85% of patients are HCV antibody-positive. The mean age of HCWs was 31.5 years and they reported an average of 0.6±1.2 needlesticks/HCW/year. The prevalence of anti-HCV, hepatitis B surface antigen (HBsAg) and co-infection was 16.6%, 1.5% and 0.2%, respectively. HCV-RNA was present in 72.1% of anti-HCV-positive HCWs, and all but one subject were infected with HCV genotype 4. Schistosoma mansoni antibodies were present in 35.1%. The anti-HCV rate increased sharply with age and employment duration, but not among those with needlestick history. After adjusting for other risk factors, the anti-HCV rate was higher among older HCWs [P<0.001; risk ratio (RR) = 1.086, 95% CI 1.063–1.11], males (P=0.002; RR=1.911, 95% CI 1.266–2.885) and those with rural residence (P<0.001; RR=2.876, 95% CI 1.830–4.52). Occupation (P=0.133), duration of employment (P=0.272) or schistosomal antibody positivity (P=0.152) were not significant risk factors for anti-HCV positivity. In conclusion, although one in six HCWs had been infected with HCV, the infections were more likely to be community-acquired and not occupationally related.

Monitoring the hepatitis A virus in urban wastewater from Rio de Janeiro, Brazil

Tatiana Prado, Tulio M. Fumian, Marize P. Miagostovich, Ana Maria C. Gaspar — 2012-02-01

Abstract: Hepatitis A is a viral disease with a significant public health impact, especially in developing countries. Improvements in sewage services could prevent hepatitis A virus (HAV) dissemination into the environment and minimize the risk of infection. The aim of this study was to monitor HAV for one year in urban sewage samples from the largest wastewater treatment plant in Rio de Janeiro, Brazil to assess environmental contamination with HAV and its dissemination after treatment by an activated sludge process. For this purpose, 48 samples (24 raw sewage samples and 24 treated effluent samples) were collected from August 2009 to July 2010 for HAV detection.Using quantitative real-time PCR 14 (58%) raw sewage samples were positive for HAV, and the highest viral genome loads were detected in the spring and summer. HAV was not detected in treated effluent samples, which suggests that the viral loads observed could be easily removed by the activated sludge process, thus preventing the dissemination of HAV into the environment. All of the HAV strains sequenced belonged to subgenotype IA, which clustered closely with Brazilian and Argentine HAV strains. These data demonstrate that environmental monitoring can be a useful tool in epidemiological studies.

Pathways of care-seeking during fatal infant illnesses in under-resourced South African settings

2012-02-01

Summary: The purpose of this study was to examine care-seeking during fatal infant illnesses in under-resourced South African settings to inform potential strategies for reducing infant mortality. We interviewed 22 caregivers of deceased infants in a rural community and 28 in an urban township. We also interviewed seven local leaders and 12 health providers to ascertain opinions about factors contributing to infant death.Despite the availability of free public health services in these settings, many caregivers utilized multiple sources of care including allopathic, indigenous and home treatments. Urban caregivers reported up to eight points of care while rural caregivers reported up to four points of care. The specific pathways taken and combinations of care varied, but many caregivers used other types of care shortly after presenting at public services, indicating dissatisfaction with the care they received. Many infants died despite caregivers’ considerable efforts, pointing to critical deficiencies in the system of care serving these families. Initiatives that aim to improve assessment, management and referral practices by both allopathic and traditional providers (for example, through training and improved collaboration), and caregiver recognition of infant danger signs may reduce the high rate of infant death in these settings.

Lymphatic filariasis in western Ethiopia with special emphasis on prevalence of Wuchereria bancrofti antigenaemia in and around onchocerciasis endemic areas

2012-02-01

Summary: Lymphatic filariasis is known to be endemic in Gambella Region, western Ethiopia, but the full extent of its endemicity in other regions is unknown. A national mapping program for Ethiopia was initiated in 2008. This report summarizes initial data on the prevalence of Wuchereria bancrofti antigenaemia based on surveys carried out in a sampled population of 11685 individuals living in 125 villages (112 districts) of western Ethiopia. The overall prevalence rate was 3.7%, but high geographical clustering and variation in prevalence (ranging from 0% to more than 50%) was found. The prevalence of hydrocele (in males) and lymphoedema of limbs was 0.8% and 3.6% respectively. Significantly higher (χ2=49.6; P<0.01) prevalence of antigenaemia was noted in known onchocerciasis endemic districts (4.7%) compared to non-onchocerciasis endemic districts (2.3%). Thirty-four of the 112 districts, with a population of 1547685 in 2007, were found to be endemic. Of these, the numbers of districts with prevalence rates of >20%, 10–20% and 5–9% were nine, 14 and 20 respectively. Twenty-nine of these 34 endemic districts were found in three regions: Gambella Region (seven districts), Beneshangul-Gumuz Region (13 districts), and Southern Nations, Nationalities and Peoples’ Region (SNNPR) (nine districts). The other five were from Amhara (two districts) and Oromia (three districts) regions. A tentative distribution map has been drawn to facilitate the launching of the Ethiopia LF elimination program.

The impact of baseline faecal egg counts on the efficacy of single-dose albendazole against Trichuris trichiura

B. Levecke, Z. Mekonnen, M. Albonico, J. Vercruysse — 2012-02-01

Abstract: There is considerable variation in the efficacy of single-dose albendazole (400mg) against Trichuris trichiura across human trials. Factors contributing to this variation have not yet been identified. We assessed the impact of mean baseline faecal egg counts (FEC) on the efficacy of single-dose albendazole against T. trichiura in five previously conducted trials. Our results suggest that efficacy measured by reduction in mean FECs decreased significantly (p<0.0001) when mean baseline FECs increased, highlighting that this parameter should be considered as an important confounding factor for drug efficacy. [ClinicalTrials.gov Identifiers: NCT01087099 and NCT01327469]

Diagnostic use of Burkholderia pseudomallei selective media in a low prevalence setting

Baharudin Roesnita, Sun Tee Tay, Savithri D. Puthucheary, I-Ching Sam — 2012-02-01

Abstract: Routine use of selective media improves diagnosis of Burkholderia pseudomallei, but resources may be limited in endemic developing countries. To maximise yield in the relatively low-prevalence setting of Kuala Lumpur, Malaysia, B. pseudomallei selective agar and broth were compared with routine media for 154 respiratory specimens from patients with community-acquired disease. Selective media detected three additional culture-positive specimens and one additional melioidosis patient, at a consumables cost of US$75. Burkholderia pseudomallei was not isolated from 74 diabetic foot ulcer samples. Following careful local evaluation, focused use of selective media may be cost-effective.

Is leishmaniasis widespread in Spain? First data on canine leishmaniasis in the province of Lleida, Catalonia, northeast Spain

C. Ballart, M.M. Alcover, M. Portús, M. Gállego — 2012-02-01

Summary: Canine leishmaniasis (CanL) is a widespread disease present in 42 countries. It is considered of epidemiological importance because of its role as a reservoir of human leishmaniasis. Knowledge of the real distribution of CanL and its emergence and/or re-emergence is of great importance in order to determine the extension of the disease. This work reports the detection of CanL in a farm dog located in a Pyrenean area of northwest Catalonia (Spain) where the disease was previously unknown. Since the dog had never left the region and sandfly vectors, Phlebotomus ariasi and P. perniciosus, were present in the farm the case is considered as autochthonous and is the first to be published in this region of Spain.