| Leishmania braziliensis | |
|---|---|
Scientific classification  | |
| Domain: | Eukaryota |
| Phylum: | Euglenozoa |
| Class: | Kinetoplastea |
| Order: | Trypanosomatida |
| Genus: | Leishmania |
| Species: | L. braziliensis |
| Binomial name | |
| Leishmania braziliensis Vianna, 1911 | |
Leishmania braziliensis is a Leishmania species found in South America. [1] It is associated with leishmaniasis.
Within a few months of infection, an ulcer forms. After healing there is an asymptomatic phase for three to twenty years. At this time, the parasite causes oral and nasal lesions causing severe damage to the mucus membranes.
Visceral leishmaniasis causes the infected to have a fever, skin lesions, skin tumors, loss in weight, spleen and liver enlargement, and if left untreated, death. [2]
Pentostam, liposomal and lipid complex preparations of amphotericin B, or paromomycin can be given.
In Brazil, currently, the most common treatment for humans to cure leishmaniasis is the drug meglumine antimoniate. [3] About 80 percent of patients with cutaneous leishmaniasis respond successfully to the drug, but for disseminated leishmaniasis only 40 percent are successfully cured of the disease after one treatment, so in these cases the patients are treated for longer periods of standard therapy. Some patients undergo multiple treatments that last 60 days each time. [3] When resistance is suspected an alternative treatment is miltefosine, some times associated with liposomal amphotericin. [4]
Leishmania braziliensis, like other species of Leishmania, rely on asexual reproduction in the intermediate mammalian host to greatly increase population density. Such reproduction is often witnessed in mononuclear phagocytes (dendritic cells, monocytes, neutrophils) of the mammalian host, with the macrophages being the target white blood cell of the parasite. [5] Recently, it has been hypothesized through two studies [6] that certain members of the Leishmania genus (e.g. L. braziliensis) are capable of sexual reproduction in the gut of the sandfly vector. More work is needed to establish a clear pattern of sexual reproduction in the genus. [7]
The reproduction of the Leishmania braziliensis vector, the sandfly, is dependent on environmental conditions. Environmental conditions such as high humidity, higher temperatures, deforestation add an increased risk because it causes increased reproduction of the parasite carrying sandflies. [8] These environmental changes put more people at risk with the vector and cause a greater geographic distribution of the sandfly and, consequently, the infectious disease.
Leishmania braziliensis is a species of Leishmania or leishmaniasis that has emerged in Northeast Brazil. It is an infectious disease that is spread by a parasite in sandflies that use domestic dogs as hosts. [9] The emergence of leishmaniasis in Brazil, specifically the Northeast state of Ceará, is theorized to date back to the Great Drought of the 19th century Brazil.
The Grande Seca of 1877 to 1878 led to the mass migration of approximately 55 thousand Brazilians from Ceará to the Amazon for employment on rubber plantations. [10] The disease is easily and mostly transmitted on plantations in which the people live and work. [11]
Direct and primary evidence of leishmaniasis' existence is extremely minimal as the disease was not known to the Northeast and therefore was not identified and labeled until 1895 in Bahia. [12] However, even though there was a lack of name-calling evidence, there are still reports of a disease that matches the descriptions of Leishmania braziliensis. In 1827, before the Great Drought, Rabello cites reports from missionaries in the Amazon region seeing people with skin lesions that fit the description of the disease. In 1909, the newly graduated medical student at the time of the drought, Studart, reported a skin condition that has the potential of being leishmaniasis. [13] It is also possible that, in combination with a lack of general information and knowledge of the disease to the public plus the mass deaths and burials that occurred from 1877 to 1879, that people were dying of leishmaniasis without knowing the true cause of their death.
On December 10, 1879, Studart reported seeing more than a thousand people die in one day. [13] It is very possible that a portion of those could have died because of leishmaniasis. An unknown disease is also mentioned by Herbert Huntington Smith, to which he attributes the death of 430 thousand people out of half a million who died, crediting the cause of death for the remaining 70 thousand to "various diseases". [10] Because not many primary sources were preserved, as stated candidly by drought writer Joao Eudes da Costa, it is very difficult to find sources during this time that directly point to the presence of leishmaniasis during the Great Drought. Regardless, there is evidence of the disease before and after the drought, so it is highly likely that it was present and exacerbated during the Grande Seca.
After contracting and spreading the disease within the plantations, workers later left the Amazon and returned to the Northeast carrying the parasite and introducing the first cases of leishmaniasis to the state.
The environmental conditions and the socio-economic factors of the drought-stricken Ceará made the area perfect and the people vulnerable to the spread of leishmaniasis. The migrants and those that remained in Ceará were malnourished, immunocompromised, and suffered from poor or even lack of sanitation and housing. In addition to the fact that the state is a semiarid region, the condition of Ceará after the Grande Seca made it a breeding ground for leishmaniasis infections that resulted in the disease being cemented into the state.
Visceral leishmaniasis, which is the most common in the Northeast region of Brazil, causes the infected to have fever, skin lesions, skin tumors, loss in weight, spleen and liver enlargement, and if left untreated, death. [11] Environmental conditions, socio-economic status, demographic and human behaviors are what pose major risks to humans as well as manmade risks like migration, deforestation, urbanization, climate change, and immunosuppression. [11] Environmental conditions such as high humidity, higher temperatures, and deforestation add an increased risk because they cause increased reproduction and geographic distribution of the parasite-carrying sandflies and, consequently, of the infectious disease. [8]
Leishmaniasis has made its appearance in 1981 to 1985 in Teresina; it reached epidemic levels in 1992 with a peak in 1994. [9] These epidemics were preceded by long and severe droughts in the region. From 1986 to 2005, Ceará has had more than 49 thousand new cases of Leishmania braziliensis; this estimate is like an underestimate since it is difficult to report the number of cases in rural areas. Those suffering from the disease are living the same lifestyle and with the same vulnerabilities as the Brazilians with leishmaniasis directly after the Great Drought. The diseased in modern-day Ceará are commonly poor teenagers aged 15 to 19, working in agriculture, and are male. [3]
Leishmania braziliensis is usually referred to as a rural problem since the increased risk factors are common in rural areas of Ceará. The people of the Northeast are still the most vulnerable. The drivers of the disease target those that live in crowded and underdeveloped housing near rubbish, sewage, and polluted water sources. [8] Though the disease targets Ceará the hardest because of its conditions, migration has spread the disease to larger cities, as more droughts, famine, and lack of usable farmland have led to large migrations from rural areas to cities. [9]
This massive influx of people creates a space for the disease to spread and infect easily. Leishmaniasis is found more commonly in favelas or "shanty towns" as the residents have increased risks and live in "overcrowded conditions with inadequate housing and sanitary facilities" (Arias, J R et al.). In addition, domestic stray dogs are the "principal animal reservoir" for the disease, [9] which makes urban areas like the favelas at an even greater risk because strays are common in these areas. [14]
Leishmania is a parasitic protozoan, a single-celled organism of the genus Leishmania that is responsible for the disease leishmaniasis. They are spread by sandflies of the genus Phlebotomus in the Old World, and of the genus Lutzomyia in the New World. At least 93 sandfly species are proven or probable vectors worldwide. Their primary hosts are vertebrates; Leishmania commonly infects hyraxes, canids, rodents, and humans.
Leishmaniasis is a wide array of clinical manifestations caused by protozoal parasites of the Trypanosomatida genus Leishmania. It is generally spread through the bite of phlebotomine sandflies, Phlebotomus and Lutzomyia, and occurs most frequently in the tropics and sub-tropics of Africa, Asia, the Americas, and southern Europe. The disease can present in three main ways: cutaneous, mucocutaneous, or visceral. The cutaneous form presents with skin ulcers, while the mucocutaneous form presents with ulcers of the skin, mouth, and nose. The visceral form starts with skin ulcers and later presents with fever, low red blood cell count, and enlarged spleen and liver.
Sandfly or sand fly is a colloquial name for any species or genus of flying, biting, blood-sucking dipteran (fly) encountered in sandy areas. In the United States, sandfly may refer to certain horse flies that are also known as "greenheads", or to members of the family Ceratopogonidae. The bites usually result in a small, intensely itchy bump or welt, the strength of which intensifies over a period of 5-7 days before dissipating. Moderate relief is achieved with varying success through the application of over the counter products such as Benadryl (ingested) or an analgesic cream such as After Bite. Outside the United States, sandfly may refer to members of the subfamily Phlebotominae within the Psychodidae. Biting midges (Ceratopogonidae) are sometimes called sandflies or no-see-ums. New Zealand sandflies are in the genus of sand fly Austrosimulium, a type of black fly.
Lutzomyia is a genus of phlebotomine sand flies consisting of nearly 400 species, at least 33 of which have medical importance as vectors of human disease. Species of the genus Lutzomyia are found only in the New World, distributed in southern areas of the Nearctic and throughout the Neotropical realm. Lutzomyia is one of the two genera of the subfamily Phlebotominae to transmit the Leishmania parasite, with the other being Phlebotomus, found only in the Old World. Lutzomyia sand flies also serve as vectors for the bacterial Carrion's disease and a number of arboviruses.
Phlebotomus is a genus of "sand flies" in the Diptera family Psychodidae. In the past, they have sometimes been considered to belong in a separate family, Phlebotomidae, but this alternative classification has not gained wide acceptance.
Cutaneous leishmaniasis is the most common form of leishmaniasis affecting humans. It is a skin infection caused by a single-celled parasite that is transmitted by the bite of a phlebotomine sand fly. There are about thirty species of Leishmania that may cause cutaneous leishmaniasis.
Visceral leishmaniasis (VL), also known as kala-azar or "black fever", is the most severe form of leishmaniasis and, without proper diagnosis and treatment, is associated with high fatality. Leishmaniasis is a disease caused by protozoan parasites of the genus Leishmania.
Leishmania infantum is the causative agent of infantile visceral leishmaniasis in the Mediterranean region and in Latin America, where it has been called Leishmania chagasi. It is also an unusual cause of cutaneous leishmaniasis, which is normally caused by specific lineages. Wild canids and domestic dogs are the natural reservoir of this organism. The sandfly species Lutzomyia longipalpis serves as the primary vector for the transmission of the disease.
Leishmania major is a species of parasite found in the genus Leishmania, and is associated with the disease zoonotic cutaneous leishmaniasis. L. major is an intracellular pathogen which infects the macrophages and dendritic cells of the immune system. Though Leishmania species are found on every continent aside from Antarctica, Leishmania major is found only in the Eastern Hemisphere, specifically in Northern Africa, the Middle East, Northwestern China, and Northwestern India.
Canine leishmaniasis (LEESH-ma-NIGH-ah-sis) is a zoonotic disease caused by Leishmania parasites transmitted by the bite of an infected phlebotomine sandfly. There have been no documented cases of leishmaniasis transmission from dogs to humans. Canine leishmaniasis was first identified in Europe in 1903, and in 1940, 40% of all dogs in Rome were determined to be positive for leishmaniasis. Traditionally thought of as a disease only found near the Mediterranean basin, 2008 research claims new findings are evidence that canine leishmaniasis is currently expanding in continental climate areas of northwestern Italy, far from the recognized disease-endemic areas along the Mediterranean coasts. Cases of leishmaniasis began appearing in North America in 2000, and, as of 2008, Leishmania-positive foxhounds have been reported in 22 U.S. states and two Canadian provinces.
Leishmania donovani is a species of intracellular parasites belonging to the genus Leishmania, a group of haemoflagellate kinetoplastids that cause the disease leishmaniasis. It is a human blood parasite responsible for visceral leishmaniasis or kala-azar, the most severe form of leishmaniasis. It infects the mononuclear phagocyte system including spleen, liver and bone marrow. Infection is transmitted by species of sandfly belonging to the genus Phlebotomus in Old World and Lutzomyia in New World. The species complex it represents is prevalent throughout tropical and temperate regions including Africa, China, India, Nepal, southern Europe, Russia and South America. The species complex is responsible for thousands of deaths every year and has spread to 88 countries, with 350 million people at constant risk of infection and 0.5 million new cases in a year.
Leishmania tropica is a flagellate parasite and the cause of anthroponotic cutaneous leishmaniasis in humans. This parasite is restricted to Afro-Eurasia and is a common cause of infection in Afghanistan, Iran, Syria, Yemen, Algeria, Morocco, and northern India.
Leishmania mexicana is a species of obligate intracellular parasites of the protozoan genus Leishmania. In Mexico and Central America, this parasite is the primary cause of cutaneous leishmaniasis.
Post-kala-azar dermal leishmaniasis (PKDL) is a complication of visceral leishmaniasis (VL); it is characterised by a macular, maculopapular, and nodular rash in a patient who has recovered from VL and who is otherwise well. The rash usually starts around the mouth from where it spreads to other parts of the body depending on severity.
The Grande Seca, or the Brazilian drought of 1877–1878, was the largest and most devastating drought in Brazilian history. It caused the deaths of between 400,000 and 500,000 people. Of the 800,000 people who lived in the affected Northeastern region, around 120,000 migrated to the Amazon while 68,000 migrated to other parts of Brazil.
Leishmania amazonensis is a parasite responsible for the disease leishmaniasis. This species has been known to spread by using sandflies as its vector and a vertebrate as its primary host, just like other species of Leishmania. They have also been known to spread throughout the Brazilian Amazon region due to their ecological niches needed for survival and reproduction. However, when the host is infected, the Leishmania can cause 3 different forms of Leishmaniasis. For this species, it has been known to cause cutaneous leishmaniasis and mucocutaneous leishmaniasis. Cutaneous leishmaniasis is commonly characterized with skin lesions, which can appear localized, or throughout the body. While mucocutaneous leishmaniasis is characterized with ulcers around the skin, mouth, and nose. This form of Leishmaniasis has also been known to can spread by metastasis and can be deadly.
Lutzomyia longipalpis is a species complex of sandfly belonging to the family Psychodidae. This species is primarily present in Central and South America, but has also appeared in Mexico. There have been reports of L. longipalpis as far south as Argentina, as they are found in a wide variety of ecological conditions. Both males and females feed on sugars from plants and aphids, but only adult females feed on the blood of other mammals. The species has recently begun appearing in urban areas throughout Brazil, and serves as a key vessel for the propagation of the parasite Leishmania infantum. The presence of these flies appears to be strongly correlated to the presence of domestic chickens in Latin America. The first major urban outbreak of the lethal Visceral leishmanias epidemic was detected in Teresina, Piauí State in the early 1980s following a massive planting of acacias.
Kala azar in India refers to the special circumstances of the disease kala azar as it exists in India. Kala azar is a major health problem in India with an estimated 146,700 new cases per year as of 2012. In the disease a parasite causes sickness after migrating to internal organs such as the liver, spleen and bone marrow. If left untreated the disease almost always results in the death. Signs and symptoms include fever, weight loss, fatigue, anemia, and substantial swelling of the liver and spleen.
A Leishmaniasis vaccine is a vaccine which would prevent leishmaniasis. As of 2017, no vaccine for humans was available. Currently some effective leishmaniasis vaccines for dogs exist.
Global climate change has increased the occurrence of some infectious diseases. Infectious diseases whose transmission is impacted by climate change include, for example, vector-borne diseases like dengue fever, malaria, tick-borne diseases, leishmaniasis, zika fever, chikungunya and Ebola. One mechanism contributing to increased disease transmission is that climate change is altering the geographic range and seasonality of the insects that can carry the diseases. Scientists stated a clear observation in 2022: "the occurrence of climate-related food-borne and waterborne diseases has increased ."