Tropical Medicine and Infectious Disease — Open Access Journal

The epitome of the One Health paradigm—and of its shortcomings—rabies has been known to humankind for at least 4000 years. We review the evolution through history of concepts leading to our current understanding of rabies in dogs and humans and its prevention, as transmitted by accessible and surviving written texts. The tools and concepts currently available to control rabies were developed at the end of the 19th Century, including the first live, attenuated vaccine ever developed for humans and the first post-exposure prophylaxis (PEP) regimen. No progress, however, has been made in etiological treatment, leaving clinicians who provide care to animals or patients with symptomatic rabies as powerless today as their colleagues in Mesopotamia, 40 centuries ago. Rabies remains to date the most lethal infectious disease known to humans. Widespread access to timely, effective, and affordable PEP in rural areas of developing countries is urgently needed. Full article

Malaria has been Ethiopia’s predominant communicable disease for decades. Following the catastrophic malaria outbreak in 2003–2004, the Federal Ministry of Health (FMoH) took drastic public health actions to lower the burden of malaria. The FMoH achieved significant declines in malaria mortality and incidence, and recently declared its objective to achieve malaria elimination in low malaria transmission areas of Ethiopia by 2020. However, while the overall malaria prevalence has decreased, unpredictable outbreaks increasingly occur irregularly in regions previously considered “malaria-free”. Such outbreaks have disastrous consequences on populations of these regions as they have no immunity against malaria. The Amhara Region accounts for 31% of Ethiopia’s malaria burden and is targeted for malaria elimination by the FMoH. Amhara’s epidemiological surveillance system faces many challenges to detect in a timely manner the unpredictable and irregular malaria outbreaks that occur in areas of otherwise low transmission. Despite the evidence of a shift in malaria transmission patterns, Amhara’s malaria control interventions remain constrained to areas that are historically known to have stable malaria transmission. This paper discusses the influence of temperature and precipitation variability, entomological parameters, and human population mobility on malaria transmission patterns across the Amhara Region, and in particular, in areas of unstable transmission. We argue that malaria epidemiological surveillance systems can be improved by accounting for population movements in addition to environmental and entomological factors. However, to date, no study has statistically analyzed the interplay of population dynamics on environmental and entomological drivers of malaria transmission. Full article

In Buruli ulcer (BU) endemic communities, most mycolactone-producing mycobacteria (MPM), including Mycobacterium ulcerans, the causative agent, are present in water bodies used by inhabitants; yet, their mode of transmission is still unclear. This study aimed to assess the distribution of MPM strains, both from human suspected cases and aquatic environments, for identifying possible transmission modes within two BU endemic districts, Daloa and Tiassalé (Taabo), in Côte d’Ivoire. Collected samples were processed using conventional polymerase chain reaction and screened for the presence of non-tuberculous mycobacteria (NTM) and MPMs using 16S rRNA, IS2404 and enoyl reductase (ER) primers. MPM-positive samples were further discriminated using variable number tandem repeat (VNTR) typing and sequencing. 16S rRNA and IS2404 sequences confirmed that 94% of the clinical samples contained MPMs. For environmental samples, 53% were contaminated with NTMs, of which 17% contained MPMs particularly M. ulcerans, suggesting that water-related activities could predispose inhabitants to BU transmission. MPM discrimination by VNTR at four M. ulcerans Agy99 loci identified genotype C, previously reported in Côte d’Ivoire as the most dominant profile. Phylogenetic clustering on the basis of genetic diversity in the MIRU 1 locus showed two main M. ulcerans lineages in Côte d’Ivoire. Full article

Papua New Guinea (PNG) has a significant malaria burden, is resource constrained, and has isolated populations with limited access to health services. Home-based management is a key element of the national program that supports strategies of early detection, diagnosis and treatment. We describe the epidemiology of malaria near Lake Kutubu in the Southern Highlands Province through reported data on suspected and confirmed malaria in patients accessing public health facilities or using a novel, incentivised, social marketing approach for malaria treatment at the village level. Monthly case data reported by nine health facilities and 14 village-based providers, known as Marasin Stoa Kipas (MSK), were extracted from outpatient registers and MSK malaria case forms. Descriptive statistics of diagnostic use, monthly incidence, test positivity rate and species distribution were estimated. Summary statistics of service delivery demonstrate patient access and diagnostic coverage in program areas. From May 2005 to September 2013, 15,726 individuals were tested with either rapid diagnostic test and/or microscopy at health facilities, and 42% had a positive result for malaria (n = 6604); of these 67.1% (n = 4431) were positive for P. falciparum (alone or mixed) and 32.9% were positive for non-P. falciparum species (alone or mixed). From October 2007 to September 2013, 9687 individuals were tested with either RDT and/or microscopy at MSK sites and 44.2% (n = 4283) tested positive for malaria; of these, 65.3% (n = 2796) were positive for P. falciparum, while 34.7% (n = 1487) were positive for non-P. falciparum species. Up to April 2010 there was an intermittent and upward trend in the reported incidence of all species of confirmed malaria, reaching 50 per 1000 population per month for both sites combined, followed by a steady decline to four per 1000 population per month in 2013, with P. vivax the most common infection. This study is the most recent longitudinal overview of malaria in the Southern Highlands since 2003. It outlines patient access to a community-based model of care. The analysis shows changes in health facility versus MSK use, a strongly decreasing trend in incidence of confirmed malaria from 2010 to 2013, and a shift from predominantly P. falciparum to P. vivax infection. Full article

Mosquitoes transmit a number of harmful diseases that have an impact on local communities and visitors, and many pose a threat to neighboring countries. As federal monitoring budgets shrink across the world, the increasing importance of citizen scientists in monitoring and identifying invasive species, as well as acting to prevent these diseases, are discussed. Examples of past mosquito management programs are provided, and future directions are discussed with an emphasis on the Western Pacific Region. Full article

The zoonosis human monkeypox (MPX) was discovered in 1970, twelve years after the discovery of monkeypox virus (MPXV) in a Danish laboratory in 1958. Historically confined to West Africa (WA) and the Congo basin (CB), new epidemics in Sudan and the United States of America (USA) have fuelled new research highlighting environmental factors contributing to the expanded geographical spread of monkeypox virus (MPXV). A systematic literature review was conducted in MEDLINE^® (Ovid), MEDLINE^® (PubMed) and Google Scholar databases using the search terms: monkeypox, MPXV and “human monkeypox”. The literature revealed MPX has classic prodromal symptoms followed by a total body rash. The sole distinguishing clinical characteristic from other pox-like illnesses is the profound lymphadenopathy. Laboratory diagnosis of MPX is essential, a suitable test for endemic areas is under development but not yet available. For the time being anti-poxvirus antibodies in an unvaccinated individual with a history of severe illness and rash can suggest MPX infection. The reservoir host remains elusive yet the rope squirrel and Gambian pouched rat appear to be the most likely candidates. Transmission includes fomite, droplet, direct contact with infected humans or animals and consumption of infected meat. Though smallpox vaccination is protective against MPXV, new non-immune generations contribute to increasing incidence. Environmental factors are increasing the frequency of contact with potential hosts, thus increasing the risk of animal-to-human transmission. Increased risk of transmission through globalisation, conflict and environmental influences makes MPX a more realistic threat to previously unaffected countries. Health worker training and further development and accessibility of suitable diagnostic tests, vaccinations and anti-viral treatment is becoming increasingly necessary. Full article

Toxoplasmosis may present as a severe disease among some Egyptian patients with chronic liver disease (CLD) due to their impaired immune system, changing the course of the disease. The classical diagnosis of toxoplasmosis by serological tests is inadequate for such patients. This study was performed to highlight the role of real-time quantitative PCR (qrtPCR) test in the accurate diagnosis of toxoplasmosis among Egyptian patients with CLD. Seventy patients with CLD and 50 healthy controls were enrolled in this study. All were subjected to full clinical examinations, abdominal ultrasonography, and biochemical analysis of liver enzymes and they were investigated for markers of hepatitis B virus (HBV) and hepatitis C virus (HCV). In addition, Toxoplasma gondii (T. gondii) parasitemia was determined using qrtPCR. The results showed that T. gondii parasitemia was positive in 30% of CLD patients with highly statistically significant (p < 0.001) compared with the control group (6%). Co-infection in both T. gondii/HBV and T. gondii/HCV was 33.3% and 31.4%, respectively, with a highly significant association between T. gondii parasitemia and HCV viral load. Moreover, the results showed a significant increase of liver enzymes in the serum of patients positive for T. gondii compared with negative patients. An association between T. gondii infection and CLD was observed, and further studies will be needed to define the mechanism of this association. Full article

Dengue fever, the most common arthropod-borne viral infection in South East Asia, is increasing in prevalence due partially to increased awareness and better diagnostic methods. While haematologic complications, such as cytopeniae and bleeding, may occur in severe dengue infection due to a variety of aetiologies, reports of haemolytic anaemia in dengue fever are scant. We report a case of severe dengue fever with haemolytic anaemia following the critical phase of infection. Full article

We describe the first reported case of spotted fever group rickettsiosis in Western Australia, and two cases of probable Rickettsia honei from a new geographic focus. These findings highlight the need to raise awareness of ricksettsial infection among local clinicians as well as those treating visitors to this region, important for outdoor recreation. Full article

A group of 14 persons who live in an area of Australia endemic for the Australian paralysis tick, Ixodes holocyclus, and who were involved in regularly collecting and handling these ticks, was examined for antibodies to tick-transmitted bacterial pathogens. Five (36%) had antibodies to Coxiella burnetii, the causative agent of Q fever and three (21%) had antibodies to spotted fever group (SFG) rickettsiae (Rickettsia spp). None had antibodies to Ehrlichia, Anaplasma, Orientia, or Borrelia (Lymedisease) suggesting that they had not been exposed to these bacteria. A total of 149 I. holocyclus ticks were examined for the citrate synthase (gltA) gene of the SFG rickettsiae and the com1 gene of C. burnetii; 23 (15.4%) ticks were positive for Rickettsia spp. and 8 (5.6%) positive for Coxiella spp. Sequencing of fragments of the gltA gene and the 17 kDa antigen gene from a selection of the ticks showed 99% and 100% homology, respectively, to Rickettsia australis, the bacterium causing Queenslandtick typhus. Thus, it appears that persons bitten by I. holocyclus in NE NSW, Australia have an approximate one in six risk of being infected with R. australis. Risks of Q fever were also high in this region but this may have been due to exposure by aerosol from the environment rather than by tick bite. A subset of 74 I. holocyclus ticks were further examined for DNA from Borrelia spp., Anaplasma spp. and Ehrlichia spp. but none was positive. Some of these recognised human bacterial pathogens associated with ticks may not be present in this Australian tick species from northeastern New South Wales. Full article

As the number of Australians engaging in short-term international travel increases, so does the opportunity for importing overseas-acquired infectious diseases. This study aimed to determine knowledge of infectious disease risks and pre-travel health advice (PTHA) seeking behaviour among Western Australians travelling to Bali, Indonesia or Thailand. Passengers departing from Perth International Airport were invited to participate in a self-administered survey. The survey determined PTHA seeking behaviour, knowledge of specific disease risks, and expected disease-prevention behaviours abroad. Multivariate regression modelling was used to assess demographic and travel-related factors associated with seeking PTHA. Responses from 1334 travellers were analysed. The proportion correctly identifying specific overseas disease risks ranged from 27% to 98%. High levels of planned disease-preventive behaviours were reported; however only 32% of respondents sought PTHA for their trip, most commonly from friends/family (15%) or a GP (14%). Many travellers (87%) made online travel purchases, but few (8%) used the Internet to source PTHA. WA travellers to Bali and Thailand were unlikely to seek PTHA and knowledge varied regarding infectious disease risks associated with travel. High rates of internet use when planning travel may provide an opportunity for destination-specific health promotion messaging and should be explored. Full article