Weekly epidemiological record / Relevé épidémiologique hebdomadaire
22 SEPTEMBER 2017, 92th YEAR / 22 SEPTEMBRE 2017, 92e ANNÉE
No 38, 2017, 92, 557–572
There are 4 main forms of the disease: visceral leishmaniasis (VL, also known as kala-azar); post-kala-azar dermal leishmania...sis (PKDL); cutaneous leishmaniasis (CL); and mucocutaneous leishmaniasis (MCL). While cutaneous leishmaniasis is the most common form of the disease, visceral leishmaniasis is the most serious and can be fatal if untreated. Additionally, leishmaniasis can be classified as anthroponotic or zoonotic depending on whether the natural reservoir of the parasite is human or animal.
This report updates global epidemiological information on VL and CL to 2015, based on the main indicators published in the GHO, as of 1st September 2017.
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Lymphatic filariasis is a vector-borne neglected tropical disease that causes damage of the lymphatic system and can lead to lymphoedema (elephantiasis) and hydrocele in infected individuals. The global baseline estimate of persons affected by lymphatic filariasis is 25 million men with hydrocele an...d over 15 million people with lymphoedema. At least 36 million persons remain with these chronic disease manifestations. The disease is endemic in 72 countries. In 2016, an estimated total population of 856 million were living in areas with ongoing transmission of the causative filarial parasites and requiring mass drug administration (MDA). Lymphatic filariasis disfigures and disables, and often leads to stigmatization and poverty. Hundreds of millions of dollars are lost annually due to reduced productivity of affected patients. WHO has ranked the disease as one of the world’s leading causes of permanent and long-term disability.
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Lymphatic filariasis (LF) is a preventable neglected tropical disease (NTD) caused by infection with the filarial parasites Wuchereria bancrofti, Brugia malayi or B. timori. Mosquitos in the genera Culex, Anopheles, Mansonia and Aedes transmit the parasites from person to person. Lymphoedema and hyd...rocoele are the visible, chronic clinical consequences of the impairment of lymphatic vessels caused by infection with these parasites. WHO established the Global Programme to Eliminate Lymphatic Filariasis (GPELF) to stop transmission of infection by mass drug administration (MDA) of anthelminthics and to alleviate the suffering of people affected by the disease through morbidity management and disability prevention (MMDP). Since the start of GPELF, the number of infections has been reduced by 74% globally. The latest estimate is that 51.4 million people are infected.
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Lymphatic filariasis is a neglected tropical disease that can cause permanent disability through disruption of the lymphatic system. This disease is caused by parasitic filarial worms that are transmitted by mosquitos. Mass drug administration (MDA) of antihelmintics is recommended by WHO to elimina...te lymphatic filariasis as a public health problem. This study aims to produce the first geospatial estimates of the global prevalence of lymphatic filariasis infection over time, to quantify progress towards elimination, and to identify geographical variation in distribution of infection.
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For the molecular diagnosis of Chagas disease by real-time PCR (polymerase chain reaction), optimization of diagnostic accuracy is desirable. The detection limit of real-time PCR assays for the diagnosis of Trypanosoma cruzi in human serum is affected by various influences including the choice of th...e nucleic acid extraction assay. In this study, three nucleic acid extraction assays were compared regarding their influence on the sensitivity of a T. cruzi-specific real-time PCR with 62 reference sera containing T. cruzi target DNA (deoxyribonucleotide acid). More than 95% of the positive sera were correctly identified after all three nucleic acid extraction strategies with a detection rate ranging from 96.8% (60/62) for the worst assay to 100% (62/62) for the best one. A matched pairs analysis for the comparison of the cycle threshold (Ct) values obtained with the 59 reference samples with positive real-time PCR results after all three nucleic acid extraction schemes indicated differences in a range of about 3 Ct steps. Summarized, all three compared nucleic acid extraction schemes were basically suitable for T. cruzi-specific PCR from serum with some minor differences. However, in the case of low quantities of circulating parasite DNA in the serum of a patient with Chagas disease, even minor effects can make a difference in the individual diagnosis.
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Urogenital schistosomiasis is a common neglected tropical disease in many rural communities in African countries, with patches of infection in the Eastern Mediterranean Region. Globally, an estimated 239 million people are currently infected, with burden estimated at more than 3.5 million disability...-adjusted life years (DALYs). In many endemic areas, severely infected individuals may suffer fibrosis of the bladder, kidney damage, bladder cancer, and death if untreated. This, however, depends on several factors such as host-parasite genetics, degree and length of exposure, intensity of infection, host immune response to the parasites, and coinfections with other tropical diseases such as malaria and HIV-1.
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Human schistosomiasis otherwise called bilharzia, is a fresh- water snail transmitted intravascular debilitating disease resulting from infection by the parasitic dimorphic Schistosoma trematode worms, which lives in the bloodstream of humans. The World Health Organization (WHO) regards the disease ...as a neglected tropical disease, with an estimated 732 million persons being vulnerable to infection worldwide in renowned transmission areas. Steinmann and co-workers documented that over 200 million individuals from Africa, Asia, and South America are infected with this disease. The WHO further estimated that schistosome infections and geohelminths accounts for over 40% of the world tropical disease burden with the exclusion of malaria. Humans get infected with this disease when they make contact with water contaminated with the skin-penetrating cercariae. Prevalence of schistosomiasis, at present, is still high in sub-Saharan Africa. In 2008, 17.5 million people were treated globally for schistosomiasis, 11.7 million of those from sub-Saharan Africa only. Approximately 120 million individuals in sub-Saharan Africa have schistosomiasis-related symptoms while about 20 million undergo hardship as a result of chronic presentations of the disease.
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Schistosomiasis, also known as bilharzia, is a disease caused by parasitic worms that require two hosts: humans and certain species of snails. There are two forms of the disease, namely, intestinal schistosomiasis, caused by Schistosoma mansoni and S. japonicum, and urogenital schistosomiasis, cause...d by S. haematobium. There are less common schistosome species in some parts of the world, e.g. S. mekongi and S. intercalatum. Schistosomiasis ranks second only to malaria as the most common parasitic disease worldwide.
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Schistosomiasis, which is the second most important parasitic infection after malaria in terms of its socioeconomic impact, is responsible for the loss of an estimated 4.5 million disability-adjusted life years (DALYs) worldwide. Schistosomiasis, including both intestinal and urinary forms of the di...sease, occurs in 78 countries across the globe. An estimated 240 million people are infected, with more than 779 million living at risk globally. The majority of those infected and those at risk for infection live in low-income countries, and approximately 80% of the morbidity occurs in impoverished communities and households in sub-Saharan Africa. Within Uganda, 91 of the 134 districts are endemic for intestinal schistosomiasis caused by Schistosoma mansoni, and the eastern region, especially along Lake Victoria, has one of the highest S. mansoni burdens worldwide. Schistosoma haematobium is only endemic in the five districts of the Lango region in northern Uganda.
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Human African Trypanosomiasis, also known as sleeping sickness is a devastating parasitic disease. It is a neglected tropical disease affecting communities in Africa. In this video we take a look at the disease, how it presents and and ways to control it.
Human African trypanosomiasis (HAT) has been an alarming global public health issue. The disease affects mainly poor and marginalized people in low-resource settings and is caused by two subspecies of haemoflagellate parasite, Trypanosoma brucei and transmitted by tsetse flies. Progress made in HAT ...control during the past decade has prompted increasing global dialogue on its elimination and eradication. The disease is targeted by the World Health Organization (WHO) for elimination as a public health problem by 2020 and to terminate its transmission globally by 2030, along-side other Neglected Tropical Diseases (NTD). Several methods have been used to control tsetse flies and the disease transmitted by them. Old and new tools to control the disease are available with constraints.
Currently, there are no vaccines available. Efforts towards intervention to control the disease over the past decade have seen considerable progress and remarkable success with incidence dropping progressively, reversing the upward trend of reported cases. This gives credence in a real progress in its elimination. This study reviews various control measures, progress and a highlight of control issues, vector and parasite barriers that may have been hindering progress towards its elimination.
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Gambiense human African trypanosomiasis is a deadly infectious disease affecting West and Central Africa, South Sudan and Uganda, and transmitted between humans by tsetse flies. The disease has caused several major epidemics, the latest one in the 1990s. Thanks to recent innovations such as rapid di...agnostic tests for population screening, a single-dose oral treatment and a highly efficient vector control strategy, interruption of transmission of the causative parasite is now within reach. If indeed gHAT has an exclusively human reservoir, this could even result in eradication of the disease. Even if there were an animal reservoir, on the basis of epidemiological data, it plays a limited role. Maintaining adequate postelimination surveillance in known historic foci, using the newly developed tools, should be sufficient to prevent any future resurgence.
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Onchocerciasis causes skin and eye disease, visual impairment and neurological problems. It is mostly found in Africa, but also in Latin America and Yemen. The common name, ‘river blindness,’ gives a good indication where the disease can be found: the vector of the parasite, a small black fly of... the Simulium species, breeds in rivers where there is turbulence in the water, such as rapids, or where the flow is disturbed by overhanging vegetation.
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More than one million people each year become infected by parasites that cause the disease cutaneous leishmaniasis (CL). This disease manifests as one or more skin lesions or ulcers that are slow to heal with variable response rates to drug treatments. Thus far, little attention has been paid to how... the cultural effects of gender shape perceptions and experiences of CL. This review aims to bring together and analyse existing studies which use qualitative data to explore these differences. These studies offered insights into our specific research questions.
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Map of Distribution of clonorchiasis, worldwide.
Foodborne trematodes are a group of diseases that include the parasites Clonorchis, Opisthorchis, Fasciola and Paragonimus. These parasitic flukes have a complex life cycle involving diverse definitive hosts and one or two intermediate hosts. Foodbo...rne trematodes cause infection in humans via the consumption of contaminated food (raw fish, crustaceans or vegetables). Infection can result in severe liver and lung disease and together these diseases are estimated to cause 2 million life years lost to disability and death worldwide every year.
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Leishmaniasis is a major vector-borne disease caused by obligate intramacrophage protozoa of the genus Leishmania, and transmitted by the bite of phlebotomine female sand flies of the genera Phlebotomus and Lutzomyia, in the old and new worlds, respectively. Among 20 well-recognized Leishmania speci...es known to infect humans, 18 have zoonotic nature, which include agents of visceral, cutaneous, and mucocutaneous forms of the disease, in both the old and new worlds. Currently, leishmaniasis show a wider geographic distribution and increased global incidence. Environmental, demographic and human behaviors contribute to the changing landscape for zoonotic cutaneous and visceral leishmaniasis. The primary reservoir hosts of Leishmania are sylvatic mammals such as forest rodents, hyraxes and wild canids, and dogs are the most important species among domesticated animals in the epidemiology of this disease. These parasites have two basic life cycle stages: one extracellular stage within the invertebrate host (phlebotomine sand fly), and one intracellular stage within a vertebrate host. Co-infection with HIV intensifies the burden of visceral and cutaneous leishmaniasis by causing severe forms and more difficult to manage. The disease is endemic to Ethiopia, and the clinical signs are not pathognomic. The visceral form (Kala-azar) may be confused with other similar conditions such as malaria, tropical splenomegaly, schistosomiasis, milliary tuberculosis, and brucellosis. Similarly, cutaneous leishmaniasis should be differentiated from disease like tropical ulcers, impetigo and leprosy. There are several methods of laboratory diagnosis of leishmaniasis, including parasitological, immunological and molecular. Different forms of treatments are available including oral, parenteral, and topical medications such as pentavalent antimonials, liposomal amphotericin B, miltefosine and paromomycin. Methods of control are largely limited to destruction of animal reservoirs, treatment of infected humans, and management of sand fly populations. Development of an effective vaccine against leishmaniasis has been largely unsuccessful and hinders its prevention.
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Leishmaniases are a group of diseases of zoonotic importance caused by over 20 species of protozoa of the genus Leishmania, in which domestic dogs are considered to be the main reservoir for the disease. However, the involvement of other vertebrates as reservoirs for these parasites has also been in...vestigated. Therefore, the objective of the present study was to carry out a systematic review with meta-analysis on occurrences of leishmaniasis in equids. The case reports described animals with cutaneous symptoms of leishmaniasis (papules, nodules, ulcers or crusts) that regressed spontaneously, located mainly on the head and limbs, from which three species of protozoa were identified in the lesions: Leishmania braziliensis, Leishmania infantum and Leishmania siamensis. In turn, the meta-analysis showed a combined prevalence of 25%, although with high heterogeneity among the studies, which was attributed to the use of different methods for diagnosing the disease. Leishmaniasis in equids is a benign disease but it should be included in the differential diagnosis of cutaneous diseases among these species. Seroepidemiological studies are important in investigating and monitoring suspected exposure of these hosts to the parasite, especially in endemic areas. However, there is also a need to standardize diagnostic methods.
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Leishmaniasis is a vector-borne disease with a broad global distribution and an increasing number of recorded cases worldwide. However, it is still one of the world's most neglected diseases. Over the last decades, the disease has been found to expand geographically with a global increase of cases o...f visceral and cutaneous leishmaniasis increasing the public health problems associated with the disease epidemics. The reported range expansion of the diseases has been associated with range expansions of vector populations in response to climate change. Leishmaniasis is caused by protozoan parasites of the genus Leishmania. The transmission can either be zoonotic and/or anthroponotic through the bite of an infected female phlebotomine sandfly. In Eurasia and Africa, all vector-competent sandfly species belong to the genus Phlebotomus. Cutaneous leishmaniasis (CL) is the most common form of leishmaniasis. In the ‘old world’, it is caused by five currently recognized Leishmania species: L. major, L. tropica and L. aethiopica (being main causative parasites) as well as L. infantum and L. donovani. Visceral leishmaniasis (VL), another common and more severe form of leishmaniasis, is only associated with the Leishmania species L. infantum and L. donovani. The specific Leishmania species cause different clinical symptoms in humans.
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The previous report of the WHO Expert Committee on this disease
followed a meeting in 1995. Intensive, coordinated efforts against HAT during
the intervening 18 years have resulted in a decrease in incidence to a point at
which elimination is considered feasible. This report provides informati...on about
new diagnostic approaches, new therapeutic regimens and better understanding
of the distribution of the disease with high-quality mapping. The roles of human
and animal reservoirs and the tsetse fly vectors that transmit the parasites are
emphasized. The new information has formed the basis for an integrated strategy
with which it is hoped that elimination of HAT will be achieved. The report also
contains recommendations on the approaches that will lead to elimination of the
disease.
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Website last accessed on 10.04.2023
The Chagas disease is frequently referred to as the effects that the parasite Trypanosoma cruzi (T. cruzi) has on people’s health. However, from our perspective, Chagas is much more than that: it is a complex socioenvironmental health problem in which elemen...ts of different nature converge and interact. The biomedical and epidemiological aspects, which are most frequently addressed, are only a piece of the puzzle that needs to be complete in order to understand Chagas in all its complexity. Social, environmental, economic, political, cultural, and educational elements turn out to be essential in comprehending the magnitude of the problem without prejudice or stigmatizations.
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