van den Hurk AF, Craig SB, Tulsiani SM
… +1 more, Jansen CC
Ann Trop Med Parasitol
· 2010 Dec · PMID 21144182
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Mosquito-borne diseases continue to be a serious public-health concern in Australia. Endemic alphaviruses (including Ross River and Barmah Forest viruses) account for the majority of the arboviral notifications, while so...Mosquito-borne diseases continue to be a serious public-health concern in Australia. Endemic alphaviruses (including Ross River and Barmah Forest viruses) account for the majority of the arboviral notifications, while some flaviviruses (Murray Valley encephalitis, Japanese encephalitis and Kunjin viruses) cause occasional outbreaks of encephalitis. Dengue epidemics are increasing in frequency in northern Queensland, with the largest outbreak in 50 years occurring during the 2008-2009 wet season. Of great concern are the threats posed by the importation of exotic arboviruses, such as West Nile, chikungunya and Rift Valley fever viruses, the introduction of exotic vectors, and the potential range expansion of key Australian vectors. Environmental and anthropogenic influences provide additional uncertainty regarding the future impact of mosquito-borne pathogens in Australia. This review discusses the trends, threats and challenges that face the management of mosquito-borne disease in Australia. Topical mosquito-borne pathogens of biosecurity and public-health concern, and the potential impacts of environmental and global trends, are discussed. Finally, a short overview of the public-health response capability in Australia is provided.
Moore PR, Jansen CC, Graham GC
… +2 more, Smith IL, Craig SB
Ann Trop Med Parasitol
· 2010 Dec · PMID 21144181
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Since its discovery in a juvenile black flying fox (Pteropus alecto) in 1996, Australian bat lyssavirus (ABLV) has become the cause of a potentially important emerging disease for health authorities in Australia, with tw...Since its discovery in a juvenile black flying fox (Pteropus alecto) in 1996, Australian bat lyssavirus (ABLV) has become the cause of a potentially important emerging disease for health authorities in Australia, with two human deaths (one in 1996 and one in 1998) attributed to the virus in the north-eastern state of Queensland. In Australia, the virus has been isolated from all four species of flying fox found on the mainland (i.e. P. alecto, P. scapulatus, P. poliocephalus and P. conspicillatus) as well as a single species of insectivorous bat (Saccolaimus flaviventris). Australian bat lyssavirus belongs to the Lyssavirus genus and is closely related, genetically, to the type strain of Rabies virus (RABV). Clinically, patients infected with ABLV have displayed the 'classical' symptoms of rabies and a similar disease course. This similarity has led to the belief that the infection and dissemination of ABLV in the body follows the same pathways as those followed by RABV. Following the two ABLV-related deaths in Queensland, protocols based on the World Health Organization's guidelines for RABV prophylaxis were implemented and, presumably in consequence, no human infection with ABLV has been recorded since 1998. ABLV will, however, probably always have an important part to play in the health of Australians as the density of the human population in Australia and, consequently, the level of interaction between humans and flying foxes increase.
Ann Trop Med Parasitol
· 2010 Oct · PMID 21092396
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A description is given of Chinius eunicegalatiae n. sp. (Diptera; Psychodidae) from Laos. This is the third known species belonging to the Asiatic genus Chinius Leng, 1987. Like C. junlianensis Leng, 1987 and C. barbazan...A description is given of Chinius eunicegalatiae n. sp. (Diptera; Psychodidae) from Laos. This is the third known species belonging to the Asiatic genus Chinius Leng, 1987. Like C. junlianensis Leng, 1987 and C. barbazani Depaquit, Léger and Beales, 2006, C. eunicegalatiae n. sp. is a cavernicolous species. An absence of the R2 vein is shared with C. barbazani. A differential diagnosis with the two other known species of the genus is given. The main differential characters are the lengths of the genital filaments and of the spermathecal ducts.
Ann Trop Med Parasitol
· 2010 Oct · PMID 21092395
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In January-March 2000, the impact of intestinal helminthiases on the nutritional status of 749 pupils (353 boys and 396 girls) attending public primary schools in the Ife Central local government area of Osun state, in s...In January-March 2000, the impact of intestinal helminthiases on the nutritional status of 749 pupils (353 boys and 396 girls) attending public primary schools in the Ife Central local government area of Osun state, in south-western Nigeria, was investigated. Demographic, socio-economic and other relevant information was collected on the pupils, on the same day that a single stool sample was collected from each subject and examined, using Stoll's dilution egg-count technique. The weights, heights and ages of the subjects were recorded and converted to percentages of the reference medians for weight-for-height, weight-for-age and height-for-age. The overall prevalences of helminth infection detected among the 465 malnourished pupils (i.e. those with any form of under-nutrition) and the 284 well-nourished pupils were 32.9% and 25.4%, respectively (P=0.029). The nutritional indices of the pupils who were found helminth-infected were generally lower than those of the pupils who appeared free of intestinal helminths. The mean values for weight-for-height, for example, were higher in the apparently uninfected pupils than in those found infected with any intestinal helminth (P=0.02) or only with Ascaris lumbricoides (P=0.05). Similarly, the mean height-for-age of the pupils who were apparently uninfected was higher than the corresponding value for the pupils found hookworm-positive (P=0.003). The pupils who were each found infected with two or more species of intestinal infection had significantly lower weights-for-heights, weights-for-ages and heights-for-ages than the pupils who appeared to be helminth-free. The results of a multivariate logistic-regression analysis indicated that hookworm infection was a significant risk factor for underweight (P=0.015), wasting (P=0.033) and stunting (P=0.015) whereas Trichuris was only a significant risk factor for stunting (P=0.025). It appears that intestinal helminthiasis may play a causal or contributory role in the occurrence of childhood malnutrition, at least in the present study area. Steps should be taken to control both of these important health problems, through functional school-health programmes that provide regular deworming, supervised school meals and health education.
Ann Trop Med Parasitol
· 2010 Oct · PMID 21092394
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Presumptive malaria treatment (PMT) is a common strategy in many areas of the world, especially in settings where the facilities for diagnosis are limited. The subjects of a recent study in central Sudan, in an area with...Presumptive malaria treatment (PMT) is a common strategy in many areas of the world, especially in settings where the facilities for diagnosis are limited. The subjects of a recent study in central Sudan, in an area with a low level of Plasmodium falciparum transmission, were 322 individuals who had each presented at one of seven suburban health facilities, complaining of repeated febrile episodes. Although all were found bloodsmear-negative for malarial parasites, all were presumptively diagnosed as cases of malaria and prescribed artemisinin-based combination therapy. When pretreatment samples of blood were, however, checked for P. falciparum histidine-rich protein 2, using a rapid diagnostic test (RDT), and for Plasmodium DNA, using a PCR-based assay, only one (0.03%) of the cases was found RDT-positive and none was found PCR-positive. Although more studies are needed, in different areas and seasons, to see if these results mirror the general situation, it appears that the wide use of PMT in central Sudan, among patients who are bloodsmear-negative, is unjustified, of little, if any, benefit, and a waste of resources that are already limited. An international consortium for the revision of the conceptual aspects of malaria diagnosis and PMT is suggested.
Stewart I, Lewis RJ, Eaglesham GK
… +3 more, Graham GC, Poole S, Craig SB
Ann Trop Med Parasitol
· 2010 Oct · PMID 21092393
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Ciguatera poisoning is a food-borne neuro-intoxication caused by consumption of finfish that have accumulated ciguatoxins in their tissues. Ciguatera is a distressing and sometimes disabling condition that presents with...Ciguatera poisoning is a food-borne neuro-intoxication caused by consumption of finfish that have accumulated ciguatoxins in their tissues. Ciguatera is a distressing and sometimes disabling condition that presents with a self-limiting though occasionally severe gastro-intestinal illness, progressing to a suite of aberrant sensory symptoms. Recovery can take from days to years; second and subsequent attacks may manifest in a more severe illness. Ciguatera remains largely a pan-tropical disease, although tourism and export fish markets facilitate increased presentation in temperate latitudes. While ciguatera poisoning in the South Pacific was recognised and eloquently described by seafarers in the 18th Century, it remains a public-health challenge in the 21st Century because there is neither a confirmatory diagnostic test nor a reliable, low-cost screening method to ascertain the safety of suspect fish prior to consumption. A specific antidote is not available, so treatment is largely supportive. The most promising pharmacotherapy of recent decades, intravenous mannitol, has experienced a relative decline in acceptance after a randomized, double-blind trial failed to confirm its efficacy. Some questions remain unanswered, however, and the use of mannitol for the treatment of acute ciguatera poisoning arguably deserves revisiting. The immunotoxicology of ciguatera is poorly understood, and some aspects of the epidemiology and symptomatology of ciguatera warrant further enquiry.
Tulsiani SM, Lau CL, Graham GC
… +5 more, Van Den Hurk AF, Jansen CC, Smythe LD, McKay DB, Craig SB
Ann Trop Med Parasitol
· 2010 Oct · PMID 21092392
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Human leptospirosis is a zoonotic disease of global importance that causes significant morbidity and mortality, particularly in developing nations. In this review, the history, epidemiology, transmission, clinical presen...Human leptospirosis is a zoonotic disease of global importance that causes significant morbidity and mortality, particularly in developing nations. In this review, the history, epidemiology, transmission, clinical presentation and treatment of this disease, and its impact in Australia, are discussed. Central to this review is the delineation of diagnostic methods for the disease and the challenges that this disease presents for both the clinician and diagnostic laboratory. This information should furnish clinicians with an updated tool to help overcome a number of problems associated with the diagnosis of leptospirosis.
Boelaert M, Meheus F, Robays J
… +1 more, Lutumba P
Ann Trop Med Parasitol
· 2010 Oct · PMID 21092391
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Several tropical diseases that are essentially poverty-related have recently gained more attention under the label of 'neglected tropical diseases' or NTD. It is estimated that over 1000 million people currently suffer f...Several tropical diseases that are essentially poverty-related have recently gained more attention under the label of 'neglected tropical diseases' or NTD. It is estimated that over 1000 million people currently suffer from one or more NTD. Here, the socio-economic aspects of two NTD - human African trypanosomiasis and human visceral leishmaniasis - are reviewed. Both of these diseases affect the poorest of the poor in endemic countries, cause considerable direct and indirect costs (even though the national control programmes tend to provide free care) and push affected households deeper into poverty.
Ann Trop Med Parasitol
· 2010 Sep · PMID 20863441
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Although it has been difficult to prove the direct involvement of cockroaches (i.e. insects of the order Blattaria) in the transmission of pathogenic agents to humans, such insects often carry microorganisms that are imp...Although it has been difficult to prove the direct involvement of cockroaches (i.e. insects of the order Blattaria) in the transmission of pathogenic agents to humans, such insects often carry microorganisms that are important in nosocomial infections, and their medical importance in the spread of bacteria cannot be ruled out. In houses and institutions with poor standards of hygiene, heavy infestations with cockroaches, such as the peridomestic American cockroach (Periplaneta americana L.) and the domestic German cockroach (Blattella germanica L.), can occur. In the present study, cockroaches (126 B. germanica and 69 P. americana) were collected from four buildings (three public training hospitals and one house) in central Tehran, Iran. Each insect was processed, under sterile conditions, so that the bacteria on its external surfaces and in its alimentary tract and faecal pellets could be isolated and identified. The oldest and largest of the three hospitals sampled (a 1400-bed unit built 80 years ago) appeared to be the one most heavily infested with cockroaches, and cockroaches from this hospital accounted for most (65.4%) of the isolates of medically important bacteria made during the study. No significant difference was found between the percentages of P. americana and B. germanica carrying medically important bacteria (96.8% v. 93.6%; P>0.05). At least 25 different species of medically important bacteria were isolated and identified, and at least 22 were Gramnegative. The genus of enteric bacteria most frequently isolated from both cockroach species, at all four collection sites, was Klebsiella. The cockroaches from each hospital were much more likely to be found contaminated with medically important bacteria than those from the house. The hospital cockroaches were also more likely to be carrying medically important bacteria internally than externally (84.3% v. 64.1%; P<0.05). The implications of these and other recent results, for the control of cockroaches and nosocomial infections, are discussed.
Ann Trop Med Parasitol
· 2010 Sep · PMID 20863440
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A serological assay was developed to assess the outcome of the treatment of intestinal schistosomiasis with praziquantel, in patients with Schistosoma mansoni infection. Each of 33 patients (seven found to be excreting S...A serological assay was developed to assess the outcome of the treatment of intestinal schistosomiasis with praziquantel, in patients with Schistosoma mansoni infection. Each of 33 patients (seven found to be excreting S. mansoni eggs and 26 egg-negatives found seropositive for antibodies against antigens from S. mansoni eggs) had two to five serum specimens assayed, the sera being collected at the time of diagnosis and at least once after praziquantel treatment. The sera were tested in ELISA against three antigen preparations: the unfractionated soluble egg antigens of S. margrebowiei and S. mansoni (SmSEA) and a cationic antigen fraction (CEF6) purified from the SmSEA. The dynamics of the post-treatment antibody levels were variable. In a minority of the patients, antibody levels declined relatively rapidly (within 5-12 months), to ELISA negativity, with the levels of the anti-CEF6 antibodies declining more rapidly than those of the anti-SmSEA antibodies. In the remaining patients, however, the levels of these specific antibodies declined only slowly or not at all over a 2- to 3-year period. The post-treatment monitoring of the levels of anti-schistosome-egg antibodies, particularly those of anti-CEF6 antibodies, may help to distinguish the treatments that result in parasitological cure from those that are only partially successful.
Yakoob J, Abbas Z, Beg MA
… +4 more, Naz S, Khan R, Islam M, Jafri W
Ann Trop Med Parasitol
· 2010 Sep · PMID 20863439
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Giardia lamblia and Cryptosporidium parvum are both waterborne pathogens associated with diarrhoea in developing countries. In a recent study based at the Aga Khan University in Karachi, 334 adults aged 16-83 years (178...Giardia lamblia and Cryptosporidium parvum are both waterborne pathogens associated with diarrhoea in developing countries. In a recent study based at the Aga Khan University in Karachi, 334 adults aged 16-83 years (178 patients with chronic diarrhoea and 156 diarrhoea-free volunteers who acted as controls) were checked for infection with these parasites, using stool microscopy and/or PCR. Overall, 21 (6.3%) and 29 (8.7%) of the subjects were found positive for G. lamblia by microscopy and PCR, respectively, while the corresponding values for C. parvum were 13 (3.9%) and 14 (4.2%). Although, compared with the diarrhoea-free controls, the patients with diarrhoea were not significantly more likely to be found infected with Giardia, either by microscopy [15 (8.4%) v. six (3.8%); P=0.085] or PCR [19 (10.7%) v. 10 (6.4%); P=0.167], they were significantly more likely to be found infected with C. parvum, both by microscopy [11 (6.2%) v. two (1.3%); P=0.024] and by PCR [12 (6.7%) v. two (1.3%); P=0.014]. The 19 patients found PCR-positive for Giardia comprised 10 (67%) of the 15 found smear-positive for the same parasite but only nine (5%) of the 163 found smear-negative (k=0.545; P<0.001). Similarly, the 12 patients found PCR-positive for Cryptosporidium comprised all 11 (100%) patients found smear-positive for the same parasite but only one (0.6%) of the 167 found smear-negative (k=0.954; P<0.001). Although C. parvum was associated with chronic diarrhoea in the present study, the carriage of G. lamblia often appeared asymptomatic.
Ann Trop Med Parasitol
· 2010 Sep · PMID 20863438
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In a cross-sectional study to determine the seroprevalence of, and possible risk factors for, Toxoplasma gondii infection in the pregnant women of Saudi Arabia, all of the pregnant Saudi women attending the Al Ahsa Mater...In a cross-sectional study to determine the seroprevalence of, and possible risk factors for, Toxoplasma gondii infection in the pregnant women of Saudi Arabia, all of the pregnant Saudi women attending the Al Ahsa Maternity Hospital over a 1-year period were invited to participate. In an interview with each subject, the relevant socio-demographic data and information on housing conditions, previous obstetric history and possible risk factors for Toxoplasma infection (e.g.frequency of consumption of undercooked meat, unwashed raw vegetables and/or unwashed raw fruit, contact with soil, and main sources of drinking water) were collected. Each subject was then checked for anti-Toxoplasma gondii IgG and IgM in commercial ELISA. Of the 554 expectant women investigated, 51.4% were found seropositive for anti-Toxoplasma IgG (indicating chronic infection) and 8.8% for anti-Toxoplasma IgM (indicating acute infection), with 6.1% of the women seropositive for Toxoplasma -specific IgM but seronegative for Toxoplasma-specific IgG. Acute infection was most common among the women who were relatively young, lived in rural areas and had relatively low incomes. The results of a multivariate logistic regression indicated that the significant positive predictors for chronic Toxoplasma infection were increasing age, rural residence, low family income, frequent consumption of undercooked meat, and previous obstetric problems (and/or multiparity). Although of questionable accuracy, the results of the present study revealed a relatively high seroprevalence of (possibly primary) acute Toxoplasma infection in the pregnant women, with the potential for transmission of the parasite to the foetuses.
Mayer JP, Biancardi M, Altcheh J
… +3 more, Freilij H, Weinke T, Liesenfeld O
Ann Trop Med Parasitol
· 2010 Sep · PMID 20863437
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Little is known about the immune responses of newborns with congenital Chagas disease (CCD) or congenital toxoplasmosis (CT) but they probably differ to those seen in adults with Chagas disease or toxoplasmosis, leading...Little is known about the immune responses of newborns with congenital Chagas disease (CCD) or congenital toxoplasmosis (CT) but they probably differ to those seen in adults with Chagas disease or toxoplasmosis, leading to differences in pathology. The concentrations of interleukin-18 (IL-18), interferon-γ (IFN-γ) and interleukin 10 (IL-10) in the sera of infants with CCD or CT were determined and compared with those in the sera of uninfected controls (born to mothers who were seropositive or seronegative for Trypanosoma cruzi). The infants with CCD or CT were found to have lower IL-18 and IFN-γ concentrations but higher IL-10 concentrations than the uninfected controls. The IL-18 and IFN-γ concentrations were also significantly lower in the infants with CCD than in those with CT. Although the infants with symptomatic CT had significantly higher serum concentrations of IL-18 than those with asymptomatic infection with Toxoplasma, the infants with symptomatic CCD had similar serum concentrations of IL-18 to the infants with asymptomatic Tr. cruzi infection. Taken together, these results indicate that IL-10 contributes to the suppression of pro-inflammatory immune responses and therefore, perhaps, to clinically overt CCD and CT.
Santos AO, Santin AC, Yamaguchi MU
… +4 more, Cortez LE, Ueda-Nakamura T, Dias-Filho BP, Nakamura CV
Ann Trop Med Parasitol
· 2010 Sep · PMID 20863436
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An essential oil was recently extracted from the leaves and flowers of yarrow (Achillea millefolium) and tested for in-vitro activity against Leishmania amazonensis and murine macrophages (i.e. the J774G8 cell line). The...An essential oil was recently extracted from the leaves and flowers of yarrow (Achillea millefolium) and tested for in-vitro activity against Leishmania amazonensis and murine macrophages (i.e. the J774G8 cell line). The median inhibitory concentration (IC(50)) against L. amazonensis promastigotes was 7.8 μg/ml whereas the survival of amastigotes of this pathogen, within peritoneal murine macrophages, was halved by treatment with the oil at 6.5 μg/ml. The mean value for the median cytotoxic concentration of the oil, measured against adherent (uninfected) J774G8 macrophages, was 72.0 μg/ml (i.e. 9.2 and 11.0 times higher, respectively, than the IC(50) against the promastigotes and intracellular amastigotes). Scanning electron microscopy revealed that the oil caused morphological changes in the treated parasites, including alterations in their shape and size. In transmission electron microscopy, promastigotes treated with the oil (at the IC(50) of 7.8 μg/ml) showed various ultrastructural alterations, including changes in the flagellar membrane, abnormal membrane structures, rupture of the plasma membrane, atypical vacuoles, myelin-like figures, and vesicles that resembled autophagic vacuoles.
Ann Trop Med Parasitol
· 2010 Sep · PMID 20863435
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Cholera diarrhoea remains a major global health problem that has caused seven pandemics. The pathogenesis of cholera is attributable to the production of cholera toxin by the causative pathogen, Vibrio cholerae. The toxi...Cholera diarrhoea remains a major global health problem that has caused seven pandemics. The pathogenesis of cholera is attributable to the production of cholera toxin by the causative pathogen, Vibrio cholerae. The toxin causes increased production of cyclic adenosine monophosphate and this results in massive water and electrolyte secretion into the intestinal lumen. These changes manifest clinically as the painless defecation of voluminous stools that resemble 'rice water', leading to severe dehydration. The cornerstone in the management of cholera diarrhoea is the use of oral rehydration solutions (ORS) to replace the water and electrolytes lost as stools. The World Health Organization recommends the use of ORS of 'reduced osmolarity' for the treatment of acute non-cholera diarrhoea and the use of rice-based ORS for the management of cholera diarrhoea. Although several attempts have been made to improve ORS, studies to evaluate some of the modifications, which include the addition of amylase-resistant starch, the use of amino acids (such as glycine, alanine and glutamine) as sodium cotransporters, and zinc-supplemented ORS, are still needed.
Ann Trop Med Parasitol
· 2010 Sep · PMID 20863434
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Filarial parasites are known to induce a large range of immunoregulatory mechanisms, including the induction of alternatively activated macrophages and regulatory T cells. These mechanisms are used to evade and down-modu...Filarial parasites are known to induce a large range of immunoregulatory mechanisms, including the induction of alternatively activated macrophages and regulatory T cells. These mechanisms are used to evade and down-modulate the host's immune system, to support parasite survival. Several reports have focused on some of these mechanisms, in humans and murine models, but the complex immunoregulatory networks associated with filarial infections remain unclear. Recent publications have conferred a role for regulatory T cells in the ability of helminth parasites to modulate human immune responses, such cells promoting the induction of the non-complement-fixing immunoglobulin G4 (IgG4). High plasma concentrations of IgG4 have been reported in hypo-responsive and asymptomatic cases of helminth infection. In both human lymphatic filariasis and onchocerciasis, the asymptomatic infections are characterised by high plasma concentrations of IgG4 (compared with those of IgE) and of the complement-fixing antibodies IgG1, IgG2 and IgG3. In asymptomatic filarial infection, elevations in IgG4 are also often associated with high worm loads and with high plasma levels of the immunomodulatory interleukin-10. Here, various aspects of the induction of IgG4 in humans and it roles in the immunomodulation of the human responses to filarial parasites are reviewed.