Nazario Bevilacqua

Seroprevalence of dengue infection: a cross-sectional survey in mainland Tanzania and on Pemba Island, Zanzibar

OBJECTIVE Evidence available to date indicates that dengue viruses 1, 2, and 3 could be among the causes of acute fever in eastern Africa. Recently, four reports on dengue infection in travelers and residents have raised concerns over the occurrence of dengue fever in mainland Tanzania and in Zanzibar. The objective of this study was to provide seroprevalence data on dengue infection in Tanzania. METHODS This study was conducted in 2007 at two peripheral hospitals, one on Pemba Island, Zanzibar and one in Tosamaganga, Iringa Region, mainland Tanzania. Two hundred and two consecutive febrile outpatients were studied for antibodies and viral RNA to assess the circulation of dengue virus in Tanzania. RESULTS A seroprevalence of 7.7% was found on Pemba Island and of 1.8% was found in Tosamaganga. No acute cases and no previous infections among patients under 11 years of age were detected. CONCLUSION These findings provide the first baseline data on dengue seroprevalence in the country. No recent dengue virus circulation in Tanzania and in the Zanzibar archipelago up until the early 1990s is reported.

Detection of Pulmonary tuberculosis: comparing MR imaging with HRCT

BackgroundComputer Tomography (CT) is considered the gold standard for assessing the morphological changes of lung parenchyma. Although novel CT techniques have substantially decreased the radiation dose, radiation exposure is still high. Magnetic Resonance Imaging (MRI) has been established as a radiation- free alternative to CT for several lung diseases, but its role in infectious diseases still needs to be explored further. Therefore, the purpose of our study was to compare MRI with high resolution CT (HRCT) for assessing pulmonary tuberculosis.Methods50 patients with culture-proven pulmonary tuberculosis underwent chest HRCT as the standard of reference and were evaluated by MRI within 24 h after HRCT. Altogether we performed 60 CT and MRI examinations, because 10 patients were also examined by CT and MRI at follow- up. Pulmonary abnormalities, their characteristics, location and distribution were analyzed by two readers who were blinded to the HRCT results.ResultsArtifacts did not interfere with the diagnostic value of MRI. Both HRCT and MRI correctly diagnosed pulmonary tuberculosis and identified pulmonary abnormalities in all patients. There were no significant differences between the two techniques in terms of identifying the location and distribution of the lung lesions, though the higher resolution of MRI did allow for better identification of parenchymal dishomogeneity, caseosis, and pleural or nodal involvement.ConclusionTechnical developments and the refinement of pulse sequences have improved the quality and speed of MRI. Our data indicate that in terms of identifying lung lesions in non-AIDS patients with non- miliary pulmonary tuberculosis, MRI achieves diagnostic performances comparable to those obtained by HRCT but with better and more rapid identification of pulmonary tissue abnormalities due to the excellent contrast resolution.

Plasmodium falciparum multiple infections, disease severity and host characteristics in malaria affected travellers returning from Africa.

BACKGROUND The pathogenesis of malaria is the result of complex interactions between parasites, host and environment. Several studies have assessed the role of genetic characteristics of Plasmodium falciparum infection in the clinical severity of malaria infection comparing different genotypic determinants in mild and severe cases. The genes encoding the polymorphic merozoite surface proteins 1 (msp-1) and 2 (msp-2) and the dihydrofolate reductase (dhfr) of malaria parasites have been extensively used as markers to investigate the genetic diversity and the population structure of P. falciparum. The aim of this study was to assess the epidemiological, clinical, host- and parasite-related determinant factor of the genetic diversity of P. falciparum infections in travellers returning to Italy. METHODS Between 1998 and 2001, we have retrospectively studied 64 inpatients all returning from African malaria-endemic countries. Designation of severe malaria was determined by using the World Health Organization (WHO) definition. P. falciparum infections detected by species-specific PCR were genotyped at the msp-1 and msp-2 loci and clones were determined. PCR and enzyme-digestion methods were used to screen the mutation occurring at codon 108. RESULTS Multiple P. falciparum genotypes were detected in 32 patients (50%). The number of genotypes was correlated to different host characteristics. No association was found between allelic number of msp-1 or msp-2 and season of travel, absence of antimalarial prophylaxis, length of stay or blood parasitemia. At multiple analysis adjusted for few confounding variables, two variables showed a significant association with multiplicity of P. falciparum genotypes: male gender (p=0.018) and severity of disease (p=0.044). CONCLUSION In our study all but one patients with severe malaria had a infection with a multiplicity of P. falciparum clones. At multivariate analysis the male gender, and the occurrence of severe malaria were significantly more commonly detected in patients affected by imported malaria with multiple clones.

IgG Against Dengue Virus in Healthy Blood Donors, Zanzibar, Tanzania

We conducted a seroprevalence survey among 500 healthy adult donors at Zanzibar National Blood Transfusion Services. Dengue virus IgG seroprevalence was 50.6% and independently associated with age and urban residence. These data will aid in building a surveillance, preparedness, and response plan for dengue virus infections in the Zanzibar Archipelago.

HIV-1 drug resistance in recently HIV-infected pregnant mother’s naïve to antiretroviral therapy in Dodoma urban, Tanzania

BackgroundHIV resistance affects virological response to therapy and efficacy of prophylaxis in mother-to-child-transmission. The study aims to assess the prevalence of HIV primary resistance in pregnant women naïve to antiretrovirals.MethodsCross sectional baseline analysis of a cohort of HIV + pregnant women (HPW) enrolled in the study entitled Antiretroviral Management of Antenatal and Natal HIV Infection (AMANI, peace in Kiswahili language). The AMANI study began in May 2010 in Dodoma, Tanzania. In this observational cohort, antiretroviral treatment was provided to all women from the 28th week of gestation until the end of the breastfeeding period. Baseline CD4 cell count, viral load and HIV drug-resistance genotype were collected.ResultsDrug-resistance analysis was performed on 97 naïve infected-mothers. The prevalence of all primary drug resistance and primary non-nucleoside reverse-transcriptase inhibitors resistance was 11.9% and 7.5%, respectively. K103S was found in two women with no M184V detection. HIV-1 subtype A was the most commonly identified, with a high prevalence of subtype A1, followed by C, D, C/D recombinant, A/C recombinant and A/D recombinant. HIV drug- resistance mutations were detected in A1 and C subtypes.ConclusionOur study reports an 11.9% prevalence rate of primary drug resistance in naïve HIV-infected pregnant women from a remote area of Tanzania. Considering that the non-nucleoside reverse-transcriptase inhibitors are part of the first-line antiretroviral regimen in Tanzania and all of Africa, resistance surveys should be prioritized in settings where antiretroviral therapy programs are scaled up.

Criteria for discharge of patients with Ebola virus diseases in high-income countries.

During the recent epidemic of Ebola virus disease (EVD) in west Africa,1 several health-care and aid workers infected with EVD were evacuated to Europe and the USA, where local transmission occurred in occupationally exposed health-care workers. Preparation for discharge requires an organised and evidence-based approach to ensure that the patient, health-care workers, family, and community are protected at all times. The risk of infection to others after discharge in the community and of unexpected late clinical events for the patient make discharge policies difficult to formulate.

The prevalence of antibodies to human herpesvirus 8 and hepatitis B virus in patients in two hospitals in Tanzania.

The aim of this study was to determine the seroprevalence of human herpesvirus 8 (HHV‐8) and the immunization status for hepatitis B virus (HBV) infection in febrile patients in two districts of the United Republic of Tanzania. Between February and March 2007, blood samples were collected in Pemba Island and Tosamaganga from 336 outpatients and sent to the Virology Laboratory in Rome (Italy) for testing. HHV‐8 DNA and HBV‐DNA were amplified by two in‐house molecular methods, anti‐HHV‐8 antibody titers were determined by an immunofluorescence assay (IFA), and anti‐HCV, HBsAg, anti‐HBs, and anti‐HBc were evaluated by microplate enzyme immunoassay (MEIA). The seroprevalence of HHV‐8 was 30.7% (96/313). In Pemba Island, the prevalence was lower than in Tosamaganga (14.4% vs. 46.3%). A higher prevalence of low titers of HHV‐8 IgG (<1:80, 81%) was found among those under 5 years of age. HHV‐8 DNA was detected in six seropositive patients (6.7%). The prevalence of HBsAg, anti‐HBs, and anti‐HBc was 4.3%, 37.6%, and 29.3%, respectively. Out of 277 patients, 70 had had a previous infection (25.3%). One case of occult hepatitis was found. The cover of hepatitis B vaccination was higher among children born after 2002 (66.7%) than in patients born before 2002. HHV‐8 infection is endemic in Tanzania and the seroprevalence rate was higher in the mainland than on Pemba Island. The 3.9% percentage of HBsAg in children younger than 4 years of age suggests that increased efforts are required in order to achieve universal and compulsory immunization of children against HBV. J. Med. Virol. 82:1569–1575, 2010.

Improved detection of human influenza A and B viruses in respiratory tract specimens by hemi-nested PCR.

Abstract RT-PCR is the most sensitive assay for diagnosis of influenza, due to enhanced rapidity and sensitivity as compared to classical methods. Hemi-nested RT-PCR was developed, targeting NP gene for influenza A and NS gene for influenza B, based on a previous single round RT-PCR method. The new method was compared with the previous technique for analytical sensitivity and specificity, and was applied to clinical samples from the lower and upper respiratory tract. The analytical sensitivity of hemi-nested RT-PCR was 10 (influenza A) and 4 times (influenza B) higher than the previous method. A high specificity of the new hemi-nested RT-PCR assay was observed by using whole respiratory viruses. When applied to lower respiratory tract specimens, the new method showed an increased rate of positivity as compared to the previous technique (9.3% versus 0.7% for influenza A, and 0.9% versus 0.2% for influenza B). Screening of upper respiratory tract samples collected during the seasonal 2005–2006 outbreak indicated 26.4% and 5.8% positivity for influenza A and B, respectively. The results were confirmed by sequence analysis: apart from influenza B, both influenza A subtypes H3N2 and H1N1, associated with the seasonal outbreak, were detected.

Tuberculosis case finding based on symptom screening among immigrants, refugees and asylum seekers in Rome

BackgroundIn Italy the proportion of cases of tuberculosis in persons originating from high-prevalence countries has been increasing in the last decade. We designed a study to assess adherence to and yield of a tuberculosis screening programme based on symptom screening conducted at primary care centres for regular and irregular immigrants and refugees/asylum seekers.MethodsPresence of symptoms suggestive of active tuberculosis was investigated by verbal screening in migrants presenting for any medical condition to 3 free primary care centres in the province of Rome. Individuals reporting at least one symptom were referred to a tuberculosis clinic for diagnostic workup.ResultsAmong 2142 migrants enrolled, 254 (11.9%) reported at least one symptom suggestive of active tuberculosis and 176 were referred to the tuberculosis clinic. Of them, 80 (45.4%) did not present for diagnostic evaluation. Tuberculosis was diagnosed in 7 individuals representing 0.33% of those screened and 7.3% of those evaluated for tuberculosis.ConclusionThe overall yield of this intervention was in the range reported for other tuberculosis screening programmes for migrants, although we recorded an unsatisfactory adherence to diagnostic workup. Possible advantages of this intervention include low cost and reduced burden of medical procedures for the screened population. Further evaluation of this approach appears to be warranted.

Post-caesarean section surgical site infections at a Tanzanian tertiary hospital: a prospective observational study

Few data are available on the determinants and characteristics of post-caesarean section (CS) surgical site infections (SSIs) in resource-limited settings. We conducted a prospective observational cohort study to evaluate the rates, determinants, and microbiological characteristics of post-CS SSI at the Dodoma Regional Referral Hospital (DRRH) Gynaecology and Obstetrics Department in Tanzania. Spanning a three-month period, all pregnant women who underwent CS were enrolled and followed up for 30 days. SSI following CS occurred in 224 (48%) women. Only 10 (2.1%) women received pre-incision antibiotic prophylaxis. Urgent intervention is needed to prevent and control infections and contain the rising rate of post-CS SSI at the DRRH.