Department of Biological Sciences

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Indigenous Tree Uses, Use-Values and Impact of Human Population on Forest Size, Structure and Species Richness in Uluguru, Morogoro, Tanzania
(Tanzania Journal of Science, 2004) Kacholi, David Sylvester
This study assesses tree uses and use-values as well as impacts of human population on the forest size, species richness, basal area and stand density in the Uluguru forests in Morogoro Region. Interview with locals on the tree uses were done using structured questionnaires and use-value analysis techniques were used in analysing data. Trees with a diameter at breast height ≥ 10 cm measured at 1.3 m above the ground were sampled from a total of 114 plots of 20 m x 20 m (0.04 ha) from the seven forests. A total of 42 species belonging to 20 families were listed being useful for the local livelihoods. Of the listed species, 88% serve more than one function while 64% are used for firewood and charcoaling, 45%, and 40%, are used for timber and medicinal purposes, respectively. Milicia excelsa and Sterculia quinqueloba had highest and lowest total use-value, respectively. Ocotea usambarensis is known to treat 29% of diseases while 47% and 25% of the species with medicinal values are used to treat stomach-ache and dysentery. Roots are the most utilized tree part for making traditional medicines, followed by barks and leaves. The human population density revealed a significant negative correlation with forest size (r = -0.90), species richness (r = -0.78), and stand density (r = -0.75). The study suggests for control of human population and their associated activities, provision of awareness on sustainable utilization of forest resources, use of alternative source of energy by locals and active involvement of the locals in management and conservation programmes.
Examining Career Orientations Of Information Systems Personnel in an Emerging Economy Context
(2008-12) Mgaya, Klodwig V.; Uzoka, Faith M. E.; Kitindi, Ernest G.; Shemi, Alice
A number of studies on career orientations of information systems (IS) personnel have focused on developed countries. This study attempts to examine career anchors of IS personnel from the perspective of a developing country, Botswana. The results of the study show that IS personnel in Botswana exhibit career orientations similar to those identified in literature. However, there are some variations, which are attributed to cultural and socio-economic peculiarities. The study indicates that life style does not feature as a significant career anchor in Botswana. The dominant career anchors include organizational stability (security) and sense of service (service). Gender, age, and educational qualifications tend to moderate the career anchors significantly; thus creating a partition of the anchors across demographic groups.
Variation over Time in Parasite Prevalence Among Free-ranging Chimpanzees at Gombe National Park, Tanzania
(International Journal of Primatology, 2009) Bakuza, Jared S.; Nkwengulila, Gamba
From January to September, 2005, we collected fecal samples from 60 chimpanzees at Gombe National Park, Tanzania and examined them for parasites. We compared current parasite prevalence data with previous studies to obtain a pattern of parasitism over time. There were considerable similarities in the parasite species composition and prevalence, although we noted some variations. Generally, parasite prevalence decreased over time, with the present prevalence being lower than in previous surveys. We identified 8 types of parasites, all of which had previously been documented in the chimpanzees of Gombe. Three nematodes — Oesophagostomum sp., Strongyloides fulleborni, and Abbreviata caucassica— occurred at higher prevalence (41.2–45.5%) but relatively lower than previous findings of 50–91%. We also diagnosed unidentified strongyles at a moderate prevalence (33%), lower than a previous record of 41%. Probstmayria gombensis occurred at relatively low prevalence (16.4%) vs. past observations (23–59%), while the prevalence of Trichuris sp. (7.3%) was closely similar to previous records of 5– 9%. We also observed unidentified ciliate at 9% within the same range as in previous studies (5–28%). The prevalence of Troglodytella abrassarti was 78%, closely similar to previous findings of 75%. There was no significant variation in parasite prevalence between chimpanzees of the Kasekela community and those of the Mitumba community, although the former tended to have higher prevalence of helminths than the latter. The causes of the similarities and variations in parasite prevalence over time are discussed. The study provides baseline data for monitoring of chimpanzee health at Gombe.
Plasmodium falciparum msp1 , msp2 and glurp allele frequency and diversity in sub-Saharan Africa
(Malaria Journal, 2011) Mwingira, Felista; Nkwengulila, Gamba; Schoepflin, Sonja; Sumari, Deborah; Beck, Hans-Peter; Snounou, Georges; Felger, Ingrid; Olliaro, Piero; Mugittu, Kefas
Background: The efficacy of anti-malarial drugs is assessed over a period of 28-63 days (depending on the drugs’ residence time) following initiation of treatment in order to capture late failures. However, prolonged follow-up increases the likelihood of new infections depending on transmission intensity. Therefore, molecular genotyping of highly polymorphic regions of Plasmodium falciparum msp1, msp2 and glurp loci is usually carried out to distinguish recrudescence (true failures) from new infections. This tool has now been adopted as an integral part of anti-malarial efficacy studies and clinical trials. However, there are concerns over its utility and reliability because conclusions drawn from molecular typing depend on the genetic profile of the respective parasite populations, but this profile is not systematically documented in most endemic areas. This study presents the genetic diversity of P. falciparum msp1, msp2 and glurp markers in selected sub-Saharan Africa countries with varying levels of endemicity namely Malawi, Tanzania, Uganda, Burkina Faso and São Tomé. Methods: A total 780 baseline (Day 0) blood samples from children less than seven years, recruited in a randomized controlled clinical trials done between 1996 and 2000 were genotyped. DNA was extracted; allelic frequency and diversity were investigated by PCR followed by capillary electrophoresis for msp2 and fragment sizing by a digitalized gel imager for msp1 and glurp. Results and Conclusion: Plasmodium falciparum msp1, msp2 and glurp markers were highly polymorphic with low allele frequencies. A total of 17 msp1 genotypes [eight MAD20-, one RO33- and eight K1-types]; 116 msp2 genotypes [83 3D7 and 33 FC27- types] and 14 glurp genotypes were recorded. All five sites recorded very high expected heterozygosity (HE) values (0.68 - 0.99). HE was highest in msp2 locus (HE = 0.99), and lowest for msp1 (HE = 0.68) (P < 0.0001). The genetic diversity and allelic frequency recorded were independent of transmission intensity (P = 0.84, P = 0.25 respectively. A few genotypes had particularly high frequencies; however the most abundant showed only a 4% probability that a new infection would share the same genotype as the baseline infection. This is unlikely to confound the distinction of recrudescence from new infection, particularly if more than one marker is used for genotyping. Hence, this study supports the use of msp1, msp2 and glurp in malaria clinical trials in sub-Saharan Africa to discriminate new from recrudescent infections.
Cytomegalovirus Infection Impairs Immune Responses and Accentuates T-Cell Pool Changes Observed in Mice With Aging
(2012-07) Cicin-Sain, Luka; Brien, James D.; Uhrlaub, Jennifer L.; Drabig, Anja; Marandu, Thomas F.; Zugich, Janko N.
Prominent immune alterations associated with aging include the loss of naïve T-cell numbers, diversity and function. While genetic contributors and mechanistic details in the aging process have been addressed in multiple studies, the role of environmental agents in immune aging remains incompletely understood. From the standpoint of environmental infectious agents, latent cytomegalovirus (CMV) infection has been associated with an immune risk profile in the elderly humans, yet the cause-effect relationship of this association remains unclear. Here we present direct experimental evidence that mouse CMV (MCMV) infection results in select T-cell subset changes associated with immune aging, namely the increase of relative and absolute counts of CD8 T-cells in the blood, with a decreased representation of the naïve and the increased representation of the effector memory blood CD8 T-cells. Moreover, MCMV infection resulted in significantly weaker CD8 responses to superinfection with Influenza, Human Herpes Virus I or West-Nile-Virus, even 16 months following MCMV infection. These irreversible losses in T-cell function could not be observed in uninfected or in vaccinia virus-infected controls and were not due to the immune-evasive action of MCMV genes. Rather, the CD8 activation in draining lymph nodes upon viral challenge was decreased in MCMV infected mice and the immune response correlated directly to the frequency of the naïve and inversely to that of the effector cells in the blood CD8 pool. Therefore, latent MCMV infection resulted in pronounced changes of the T-cell compartment consistent with impaired naïve T-cell function.
Floristic Composition, Diversity and Structure of the Kimboza Forest in Morogoro Region, Tanzania
(Journal of Education, Humanities and Sciences, 2013) Kacholi, David Sylvester
Kimboza forest reserve in Morogoro region, is an important biodiversity hotspot among the Eastern Arc forests of Tanzania. High population pressure and encroachment threatens its conservation values. This is based on a study which aimed at investigating the composition, diversity, and structure of the tree community in the forest. All trees with DBH ≥ 10cm were inventoried from 0.72ha in a total of 18 plots of 20m × 20m placed randomly from the forest edge to the interior. Most important families and species were determined using familial importance value (FIV) and species importance value (IVI) indices, respectively. Diversity was analyzed using species richness, Shannon-Wiener, Fisher-α, and Simpson’s indices. A total of 52 species belonging to 22 families were identified. The family Fabaceae had the highest FIV (66.70) and species richness (15 species) while Khaya anthotheca had the highest IVI value (48.11). The Shannon-Wiener (3.40), Simpson (20.60), and the Fisher-α (18.80) indices were very high signifying high floristic diversity within the forest. 69% of the species were rare, occurring in less than 20% of the surveyed plots. The mean density and basal area of trees were 390 stems ha-1 and 24 m2 ha-1, respectively. The species accumulation curve revealed an escalating trend suggesting that more sample plots could result to a number of species in the forest. In summary, the study suggests for proper management, protection, and wise utilization of the forest resources so that it sustains its original biodiversity and ecological processes for future generations.
Analysis of Structure and Diversity of the Kilengwe Forest in the Morogoro Region, Tanzania
(International Journal of Biodiversity, 2014) Kacholi, David Sylvester
This study investigates the structure, species composition, and diversity of a section of the Kilengwe Forest in Tanzania. In order to accomplish the proposed objectives, 18 plots of 20m× 20m were randomly established in the forest and the number of tree species in each plot was identified and counted. The most important families and species were determined using importance value indices at the respective taxonomic levels. Diversity was measured using the Shannon-Wiener and Fisher alpha diversity indices. A total of 276 stems/ha representing 93 species/ha within 26 families were documented from 0.72 ha. Fabaceae and Julbernadia globiflora were the dominant family and species, respectively. Seventy-eight percent of the total species were rare.The average basal area of the forest was 7.1m2/ha. The Shannon-Wiener index (4.02) and Fisher’s alpha diversity (35.5) indicated high species diversity within the forest. The species-area and species-abundance curves revealed an escalating trend implying that more sampling efforts could result in a higher number of species existing in the forest. The size class distribution displayed a reverse J-shaped pattern; however, the larger size classes DBH >50 cm were not represented.The study suggests the necessity for anthropogenic disturbance control as this is the major source of forest degradation in the studied area.
Edge-Interior Disparities in Tree Species and Structural Composition of the Kilengwe Forest in Morogoro Region, Tanzania
(ISRN Biodiversity, 2014) Kacholi, David Sylvester
A survey to determine the variation in species and structural composition of trees along the edge-interior gradient was done in the Kilengwe forest inMorogoro region, Tanzania.The forest was categorized into three habitats, namely, edge (0–100m), intermediate (100–200 m), and interior (>200m) depending on the distance from the forest margin. A total of six plots of 0.04 ha each were randomly placed in each of the habitats whereby all trees with DBH ≥ 10 cm were inventoried. A total of 67 species representing 26 families were recorded. Fabaceae was the most speciose and abundant family. Brachystegia spiciformis was the most abundant species. Of the recorded species, 10.45% were common in the three habitats while 8.95%, 13.43%, and 26.86% occurred exclusively to the edge, intermediate, and interior habitats, respectively. The forest interior was significantly rich in terms of species richness, diversity, density, and basal area than the edge and intermediate habitats.The edge had significantly higher number of stumps/ha. In summary, the results suggest that edge/intermediate and interior are contrasting habitats in terms of tree species richness, diversity, and structural composition. Moreover, the forest edge and intermediate habitats were found to be characterized by high anthropogenic activities compared to the forest interior habitat.
Mouse CMV Infection Delays Antibody Class Switch upon an Unrelated Virus Challenge
(Elsevier, 2014-01) Marandu, Thomas F.; Finsterbusch, Katja; Kröger, Andrea; Cicin-Sain, Luka
Poor immune protection upon vaccination is a critical determinant of immunosenescence. Latent Cytomegalovirus (CMV) infection has been associated with poor antibody responses to vaccination, but a causative role for CMV in the poor immune response requires experimental evidence and thus could not be confirmed in clinical studies. To test the hypothesis that latent CMV infection causes poor antibody responses, we infected young or adult mice with mouse CMV and challenged them with vesicular stomatitis virus (VSV) at 15 or 18 months of age. Latent, but not primary infection with mouse CMV resulted in diminished neutralizing titers of the serum IgG fraction at day 7 post challenge, which recovered by day 14 post challenge. This phenomenon was specific for mice infected with mouse CMV, but not mice infected with other herpesviruses, like murine herpesvirus-68 or herpes simplex virus type 1, or mice infected with non-persistent viruses, such as influenza or vaccinia virus. Hence, our data indicate a delay in IgG class-switch that was specific for the CMV infection. Herpesviral infections did not change the B-cell memory compartment, and increased the size of the effector-memory subset of blood CD4 T-cells only when administered in combination. Furthermore, CD4 T-cell response to VSV infection was maintained in latently infected mice. Therefore, our results argue that latent CMV infection impairs B-cell, but not T-cell responses to a challenge with VSV and delays antibody class-switch by a mechanism which may be independent of T-cell help.
New Advances in CMV and Immunosenescence
(Elsevier, 2014-04) Sansoni, Paolo; Vescovini, Rosanna; Fagnoni, Francesco; Akbar, Arne; Arens, Ramon; Chiu, Yen L.; Šain, Luka Č.; Merville, Julie D.; Derhovanessian, Evelyna; Martinez, Sara F.; Franceschi, Claudio; Frasca, Daniela; Fulöp, Tamas; Furman, David; Klotsas, Effrossyni G.; Goodrum, Felicia; Loebenstein, Beatrix G.; Hurme, Mikko; Kern, Florian; Liller, Daniele; Botet, Miguel L.; Maier, Andrea B.; Marandu, Thomas F.; Marchant, Arnaud; Matheï, Catharina; Moss, Paul; Muntasell, Aura; Remmerswaal, Ester B.M.; Riddell, Natalie E.; Rothe, Kathrin; Sauce, Delphine; Shin, Eui C.; Simanek, Amanda M.; Smithey, Megan J.; Nauclér, Cecilia S.; Solana, Rafael; Thomas, Paul G; Lier, Rene V.; Pawelec, Graham; Zugich, Janko N.
Immunosenescence, defined as the age-associated dysregulation and dysfunction of the immune system, is characterized by impaired protective immunity and decreased efficacy of vaccines. An increasing number of immunological, clinical and epidemiological studies suggest that persistent Cytomegalovirus (CMV) infection is associated with accelerated aging of the immune system and with several age-related diseases. However, current evidence on whether and how human CMV (HCMV) infection is implicated in immunosenescence and in age-related diseases remains incomplete and many aspects of CMV involvement in immune aging remain controversial. The attendees of the 4th International Workshop on "CMV & Immunosenescence", held in Parma, Italy, 25-27th March, 2013, presented and discussed data related to these open questions, which are reported in this commentary.
Population Pharmacokinetics and Clinical Response for Artemether-Lumefantrine in Pregnant and Nonpregnant Women with Uncomplicated Plasmodium falciparum Malaria in Tanzania
(American Society for Microbiology, 2014-07) Mosha, Dominic; Guidi, Monia; Mwingira, Felista; Abdulla, Salim; Mercier, Thomas; Decosterd, Laurent Arthur; Csajka, Chantal; Genton, Blaise
ABSTRACT Artemether-lumefantrine (AL) is the first-line treatment for uncomplicated malaria in the second and third trimesters of pregnancy. Its efficacy during pregnancy has recently been challenged due to altered pharmacokinetic (PK) properties in this vulnerable group. The aim of this study was to determine the PK profile of AL in pregnant and nonpregnant women and assess their therapeutic outcome. Thirty-three pregnant women and 22 nonpregnant women with malaria were treated with AL (80/480 mg) twice daily for 3 days. All patients provided five venous plasma samples for drug quantification at random times over 7 days. Inter- and intraindividual variability was assessed, and the effects of covariates were quantified using a nonlinear mixed-effects modeling approach (NONMEM). A one-compartment model with first-order absorption and elimination with linear metabolism from drug to metabolite fitted the data best for both arthemether (AM) and lumefantrine (LF) and their metabolites. Pregnancy status and diarrhea showed a significant influence on LF PK. The relative bioavailability of lumefantrine and its metabolism rate into desmethyl-lumefantrine were, respectively, 34% lower and 78% higher in pregnant women than in nonpregnant patients. The overall PCR-uncorrected treatment failure rates were 18% in pregnant women and 5% in nonpregnant women (odds ratio [OR] = 4.04; P value of 0.22). A high median day 7 lumefantrine concentration was significantly associated with adequate clinical and parasitological response (P = 0.03). The observed reduction in the relative bioavailability of lumefantrine in pregnant women may explain the higher treatment failure in this group, mostly due to lower posttreatment prophylaxis. Hence, a modified treatment regimen of malaria in pregnancy should be considered.
Effectiveness of intermittent preventive treatment with sulfadoxine–pyrimethamine during pregnancy on placentalmalaria, maternal anaemia and birthweight in areas with highand low malaria transmission intensity in Tanzania
(2014 John Wiley & Sons Ltd, 2014-09) Mosha, Dominic; Chilongola, Jaffu; Ndeserua, Rabi; Mwingira, Felista; Genton, Blaise
objective To assess the effectiveness of IPTp in two areas with different malaria transmission intensities. methods Prospective observational study recruiting pregnant women in two health facilities in areas with high and low malaria transmission intensities. A structured questionnaire was used for interview. Maternal clinic cards and medical logs were assessed to determine drug intake. Placental parasitaemia was screened using both light microscopy and real-time quantitative PCR. results Of 350 pregnant women were recruited and screened for placental parasitaemia, 175 from each area. Prevalence of placental parasitaemia was 16.6% (CI 11.4–22.9) in the high transmission area and 2.3% (CI 0.6–5.7) in the low transmission area. Being primigravida and residing in a high transmission area were significant risk factors for placental malaria (OR 2.4; CI 1.1–5.0; P = 0.025) and (OR 9.4; CI 3.2–27.7; P < 0.001), respectively. IPTp was associated with a lower risk of placental malaria (OR 0.3; CI 0.1–1.0; P = 0.044); the effect was more pronounced in the high transmission area (OR 0.2; CI 0.06–0.7; P = 0.015) than in the low transmission area (OR 0.4; CI 0.04–4.5; P = 0.478). IPTp use was not associated with reduced risk of maternal anaemia or low birthweight, regardless of transmission intensity. The number needed to treat (NNT) was four (CI 2–6) women in the high transmission area and 33 (20–50) in the low transmission area to prevent one case of placental malaria. conclusion IPTp may have an effect on lowering the risk of placental malaria in areas of high transmission, but this effect did not translate into a benefit on risks of maternal anaemia or low birthweight. The NNT needs to be considered, and weighted against that of other protective measures, eventually targeting areas which are above a certain threshold of malaria transmission to maximise the benefit.
Comparison of detection methods to estimate asexual Plasmodium falciparum parasite prevalence and gametocyte carriage in a community survey in Tanzania
(Springer Nature, 2014-11-18) Mwingira, Felista; Genton, Blaise; Kabanywanyi, Abdu-Noor M; Felger, Ingrid
Background The use of molecular techniques to detect malaria parasites has been advocated to improve the accuracy of parasite prevalence estimates, especially in moderate to low endemic settings. Molecular work is time-consuming and costly, thus the effective gains of this technique need to be carefully evaluated. Light microscopy (LM) and rapid diagnostic tests (RDT) are commonly used to detect malaria infection in resource constrained areas, but their limited sensitivity results in underestimation of the proportion of people infected with Plasmodium falciparum. This study aimed to evaluate the extent of missed infections via a community survey in Tanzania, using polymerase chain reaction (PCR) to detect P. falciparum parasites and gametocytes. Methods Three hundred and thirty individuals of all ages from the Kilombero and Ulanga districts (Tanzania) were enrolled in a cross-sectional survey. Finger prick blood samples were collected for parasite detection by RDT, LM and molecular diagnosis using quantitative 18S rRNA PCR and msp2 nPCR. Gametocytes were detected by LM and by amplifying transcripts of the gametocyte-specific marker pfs25. Results Results from all three diagnostic methods were available for a subset of 226 individuals. Prevalence of P. falciparum was 38% (86/226; 95% CI 31.9–44.4%) by qPCR, 15.9% (36/226; 95% CI 11.1–20.7%) by RDT and 5.8% (13/226; 95% CI 2.69- 8.81%) by LM. qPCR was positive for 72% (26/36) of the RDT-positive samples. Gametocyte prevalence was 10.6% (24/226) by pfs25-qRT-PCR and 1.2% by LM.
Understory Tree Composition, Diversity and Natural Regeneration Status of Uluguru Forests in Morogoro - Tanzania
(Journal of Education, Humanities and Sciences, 2015) Kacholi, David Sylvester
Most of the studies on tropical forests vegetation have tended to focus on trees with a diameter at breast height (DBH) greater or equal to 10cm, and limited attention has been paid to understory. This study was conducted in Uluguru forests in Morogoro region, Tanzania, with an objective of describing the understory tree composition, diversity and natural regeneration of some threatened species in the seven surveyed forests. Sampling was done in the forests whereby classification of understory was done into three layers: seedling (individuals with height < 1m), small sapling (DBH ≤ 3 cm), and large sapling (3 < DBH < 10 cm) layers. Large saplings were sampled in 20m × 20m plots, while subplots of 5m ×5m and 2m ×2m were placed at the centre of each plot for sampling small saplings and seedlings, respectively. A total of 2119 seedlings, 1798 small saplings, and 2585 large saplings belonging 91, 102, and 104 species, respectively, were recorded. Fabaceae was the most speciosefamily in all the studied compartments, and had higher familial importance value (FIV). The seedling layer had higher tree density than the large and small sapling layers, but the large and small sapling layers were more diverse than the seedling layer (p < 0.05).The species richness in each forest was significantly higher in the understory than overstory layer (p < 0.034); and the pairing was strongly positively correlated (r = 096, p = 0.0003). The Sørensen coefficients of similarities between understory and overstory ranged between 0.53–0.77, and were higher within each forest than among them. All forests revealed to have good regeneration, though it is important to understand that some species unveiled poor or hampered regeneration pattern.In summary, the understory was observed to be speciose than overstory layer; it was dominated by family Fabaceae, and the natural regeneration of the forests were good, however, some species need due attention.
Prevalence and Intensity of Schistosomiasis in Communities around Water Reservoirs in Malawi
(Journal of Tropical Diseases, 2015) Mtethiwa, Austin; Nkwengulila, Gamba; Bakuza, Jared S.
Although schistosomiasis is endemic in Malawi, its epidemiology at water reservoir communities is not known. However, there are more than 750 water reservoirs spread throughout the country, providing water for various activities. The present study was conducted to determine schistosomiasis infection at reservoir communities in Malawi. Methods: This was across sectional study conducted during the rainy and dry seasons at three water reservoir communities. A total of 1594 individuals aged from 1 to 78 years from 1-2km, >2-5km and 5km away from the reservoir were randomly selected and enrolled into the study. They provided stool and urine samples which were examined for Schistosoma eggs using Kato-Katz and sedimentation methods, respectively. Results: An overall prevalence of 47.4% was found with 51.2% for S. haematobium and 9.5% for S. mansoni. Prevalence was significantly higher during the dry season (58.5%) than the rainy season (36.6%) (P=0.01). Prevalence was significantly higher in communities living 0-2km away from the reservoir than in those living > 5km away (P=0.00). Prevalence of S. haematobium was significantly different higher at Mlala reservoir than at Ukonde and Njala reservoirs (P=0.043). Prevalence of S. Mansoni was significantly higher at Ukonde reservoir than at Mlala and Njala reservoirs (P=0.037). Prevalence among different age groups was not significantly different (P=0.29). Age group of 6-15 years had significantly higher infection intensity, in both S. mansoni (129±3.6 epg) and S. haematobium (63.3±2.3 eggs/10ml of urine), than the other age groups. Conclusion: Water reservoirs are infested with Schistosoma cercariae and the communities are at risk. The closer to the reservoir, the higher the chances of being infected. We recommend annual MDA, since the prevalence found is within the ≥50% WHO recommended threshold for MDA. We also recommend a health education to the communities on transmission and prevention of schistosomiasis.
Ultra-Sensitive Detection of Plasmodium falciparum by Amplification of Multi-Copy Subtelomeric Targets
(PLOS, 2015-03-03) Hofmann, Natalie; Mwingira, Felista; Shekalaghe, Seif; Robison, Leanne; Muller, Ivo; Felger, Ingrid
Background Planning and evaluating malaria control strategies relies on accurate definition of parasite prevalence in the population. A large proportion of asymptomatic parasite infections can only be identified by surveillance with molecular methods, yet these infections also contribute to onward transmission to mosquitoes. The sensitivity of molecular detection by PCR is limited by the abundance of the target sequence in a DNA sample; thus, detection becomes imperfect at low densities. We aimed to increase PCR diagnostic sensitivity by targeting multi-copy genomic sequences for reliable detection of low-density infections, and investigated the impact of these PCR assays on community prevalence data. Methods and Findings Two quantitative PCR (qPCR) assays were developed for ultra-sensitive detection of Plasmodium falciparum, targeting the high-copy telomere-associated repetitive element 2 (TARE-2, *250 copies/genome) and the var gene acidic terminal sequence (varATS, 59 copies/genome). Our assays reached a limit of detection of 0.03 to 0.15 parasites/μl blood and were 10× more sensitive than standard 18S rRNA qPCR. In a population cross-sectional study in Tanzania, 295/498 samples tested positive using ultra-sensitive assays. Light microscopy missed 169 infections (57%). 18S rRNA qPCR failed to identify 48 infections (16%), of which 40% carried gametocytes detected by pfs25 quantitative reverse-transcription PCR. To judge the suitability of the TARE-2 and varATS assays for high-throughput screens, their performance was tested on sample pools. Both ultra-sensitive assays correctly detected all pools containing one low-density P. falciparum–positive sample, which went undetected by 18S rRNA qPCR, among nine negatives. TARE-2 and varATS qPCRs improve estimates of prevalence rates, yet other infections might still remain undetected when absent in the limited blood volume sampled. Conclusions Measured malaria prevalence in communities is largely determined by the sensitivity of the diagnostic tool used. Even when applying standard molecular diagnostics, prevalence in our study population was underestimated by 8% compared to the new assays. Our findings highlight the need for highly sensitive tools such as TARE-2 and varATS qPCR in community surveillance and for monitoring interventions to better describe malaria epidemiology and inform malaria elimination efforts.
Extent of morbidity associated with schistosomiasis infection in Malawi: a review paper.
(Infectious Diseases of Poverty, 2015-05) Mtethiwa, Austin; Nkwengulila, Gamba; Sikawa, D.; Kazembe, A.
Data on the extent of the burden due to schistosomiasis is sparse in most Sub-Saharan African countries. However, this data is crucial for triggering medical attention. A review of extent of morbidity and determinants associated with schistosomiasis in Malawi was therefore conducted to quantify the infection in order to concretise the need for medical intervention. A systematic and traditional search strategy was used to find literature for the review, whilst exclusion and inclusion criteria were used to identify appropriate articles. Logistic regression curves of epidemiological model Y = (a + bxc)/(1 + bxc) and the recommendation that schistosomiasis prevalence can be used to estimate morbidity were employed to quantify morbidity at various infection stages. Morbidity was quantified as a direct proportion of the population and the respective national schistosomiasis prevalence. Findings showed that both S. mansoni and S. haematobium are present in Malawi with the latter highly prevalent (50%). Furthermore, out of the estimated population of 16,829 million, approximately 8.4 million have schistosomiasis, with about 4.4 million of these aged 18 years and below. The most frequent manifestation is Katayama syndrome, while ascites is the lowest, impacting about 3.0 million and 960 individuals, respectively. Localised studies on association of schistosomiasis infection to risk factors such as occupation, age and gender found odds ratio (OR) ranging from 1.29 to 5.37. Morbidity due to schistosomiasis is high in Malawi. It is therefore recommended that a more detailed study on the determinants of high schistosomiasis and re-evaluation of the current control measures be conducted if the current morbidity statistics are to be remarkably reduced
Immune Protection against Virus Challenge in Aging Mice Is Not Affected By Latent Herpesviral Infections
(2015-09) Marandu, Thomas F.; Oduro, Jennifer D.; Borkner, Lisa; Dekhtiarenko, Iryna; Uhrlaub, Jennifer; Drabig, Anja; Kröger, Andrea; Zugich, Janko N.; Sain, Luka C.
Latent herpesvirus infections alter the immune homeostasis. To understand if this results in aging-related loss of immune protection against emerging infections, we challenged old mice carrying latent mouse CMV, HSV-1 and/or MHV-68 with Influenza, WNV or VSV. We observed no increase in mortality or weight-loss over herpesvirus-negative counterparts and a relative, but no absolute reduction in CD8 responses against acute infections. Therefore, herpesviruses do not appear to increase susceptibility to emerging infections in aging. Copyright © 2015, American Society for Microbiology. All Rights Reserved
Diversity, abundance, and structure of tree communities in the Uluguru forests in the Morogoro region, Tanzania
(Journal of Forestry Research, 2015-09) Kacholi, David Sylvester; Whitbread, Anthony Michael; Worbes, Martin
Uluguru forests are globally recognized as important biodiversity hotspots, but anthropogenic pressure threatens their value. This study examined species diversity, abundance, and structure of trees in the Uluguru forests. All trees of diameter at breast height (DBH) C 10 cm were inventoried in seven forests ranging from 3 to 995 ha in area. A total of 900 stems, 101 species and 34 families were inventoried. Fabaceae was the most speciose family.Ehretia amoena Klotzsch was the most abundant species with relative abundance of 9.22 %. The forests differed significantly in species richness (26–93 species/ha), tree density (85–390 stems/ha), basal area (3–24 m2/ha) and Shannon-Wiener diversity (2.50–4.02). Forest area was significantly and positively correlated with species richness (r = 0.92) and species diversity (r = 0.95). Tree density showed significant positive correlation with species richness (r = 0.80) and basal area (r = 0.85). Milawilila and Nemele forests had highest floristic similarity (0.55) followed by Kimboza and Kilengwe (0.54) while the rest had similarity coefficients of less than 0.50. Despite legislative protection, many forests remain at risk and therefore the possibility to conserve highly valuable tree species via enhanced protection or cultivation must be considered.
Murine Cytomegalovirus Infection via the Intranasal Route Offers a Robust Model of Immunity Upon Mucosal CMV Infection
(2015-11) Oduro, Jennifer D.; Redeker, Anke; Lemmermann, Niels A. W.; Ebermann, Linda; Marandu, Thomas F.; Dekhtiarenko, Iryna; Holzki, Julia K.; Busch, Dirk; Arens, Ramon; Sain, Luka C.
Cytomegalovirus (CMV) is a ubiquitous virus, causing the most common congenital infection in humans, yet a vaccine against this virus is not available. The experimental study of immunity against CMV in animal models of infection, such as the infection of mice with the mouse CMV (MCMV), has relied on systemic intraperitoneal infection protocols, although the infection naturally transmits by mucosal routes via body fluids containing CMV. To characterize the biology of infections by mucosal routes, we have compared the kinetics of virus replication, the latent viral load, and CD8 T cell responses in lymphoid organs upon experimental intranasal and intragastric infection to intraperitoneal infection of two unrelated mouse strains. We have observed that intranasal infection induces robust and persistent virus replication in lungs and salivary glands, but a poor one in the spleen. CD8 T cell responses were somewhat weaker than upon intraperitoneal infection, but showed similar kinetic profiles and phenotypes of antigen-specific cells. On the other hand, intragastric infection resulted in abortive or poor virus replication in all tested organs, and poor T cell responses to the virus, especially at late times after infection. Consistent with the T cell kinetics, the MCMV latent load was high in the lungs, but low in the spleen of intranasally infected mice and lowest in all tested organs upon intragastric infection. In conclusion, we show here that intranasal, but not intragastric infection of mice with MCMV represents a robust model to study short and long-term biology of CMV infection by a mucosal route

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