Leishmaniasis-Sand Flies
Basic Information
Leishmaniasis is caused by protozoan parasites which are transmitted by the bite of infected female phlebotomine sandflies. The disease affects some of the poorest people and is associated with malnutrition, population displacement, poor housing, a weak immune system and lack of financial resources. Leishmaniasis is also linked to environmental changes such as removing forests, building of dams, irrigation schemes and urbanization. An estimated 700,000 to 1 million new cases occur annually. Only a small fraction of those infected by parasites causing leishmaniasis will eventually develop the disease (World Health Organization, 2022d).
The disease affects some of the poorest people and is associated with malnutrition, population displacement, poor housing, a weak immune system and lack of financial resources. Leishmaniasis is also linked to environmental changes such as removing forests, building of dams, irrigation schemes and urbanization.
Symptoms
There are three main forms of leishmaniasis: visceral, cutaneous and mucocutaneous.
Visceral Leishmaniasis (VL):
Visceral leishmaniasis (VL), also known as kala-azar is deadly if left untreated in over 95% of cases. It is characterized by irregular bouts of fever, weight loss, growth of the spleen and liver, and anemia (World Health Organization, 2022d).
Cutaneous Leishmaniasis (CL):
Cutaneous leishmaniasis (CL) is the most common form of leishmaniasis and causes skin lesions, mainly ulcers, on exposed parts of the body, leaving life-long scars and serious disability or stigma (World Health Organization, 2022d).
Mucocutaneous Leishmaniasis:
Mucocutaneous leishmaniasis leads to partial or destruction of mucous membranes of the nose, mouth, and throat (World Health Organization, 2022d).
Controls
Prevention and control of leishmaniasis requires a combination of intervention strategies. Vector control helps to reduce or interrupt transmission of disease by decreasing the number of sandflies. Control methods include insecticide spray, use of insecticide-treated nets, environmental management and personal protection (World Health Organization, 2022d).
Brucellosis
Basic Information
Brucellosis is a bacterial disease caused by various Brucella species, which mainly infect cattle, swine, goats, sheep, and dogs. Humans generally acquire the disease through direct contact with infected animals, by eating or drinking contaminated animal products, or by inhaling airborne agents. Most cases are caused by drinking unpasteurized milk or cheese from infected goats or sheep. Human-to-human transmission is very rare. Brucellosis is one of the most widespread zoonoses transmitted by animals and in endemic areas. Brucellosis is found globally and is a reportable disease in most countries (World Health Organization, 2020a).
Through direct contact with infected animals, by eating or drinking contaminated animal products or by inhaling airborne agents. Most cases are caused by drinking unpasteurized milk or cheese from infected goats or sheep.
Symptoms
The disease causes flu-like symptoms, including fever, weakness, malaise, and weight loss. The incubation period of the disease can be highly variable, ranging from 1 week to 2 months, but usually 2–4 weeks (World Health Organization, 2020a).
Controls
Prevention of brucellosis is based on surveillance and the prevention of risk factors. The most effective prevention strategy is the elimination of infection in animals. Vaccination of cattle, goats, and sheep is recommended in enzootic areas with high prevalence rates. In countries where eradication in animals through vaccination or elimination of infected animals is not feasible, prevention of human infection is primarily based on raising awareness, food-safety measures, occupational hygiene, and laboratory safety. Pasteurization of milk for direct consumption and for creating cheese is an important step to preventing transmission from animals to humans. Education campaigns about avoiding unpasteurized milk products can be effective, as well as policies on its sale (World Health Organization, 2020a).
Chagas Disease- Trypanosoma Cruzi
Basic Information
Chagas disease, also known as American trypanosomiasis, is a potentially life-threatening illness caused by the protozoan parasite Trypanosoma cruzi (T. cruzi). About six million to seven million people worldwide are estimated to be infected with Trypansosoma cruzi, the parasite that causes Chagas disease. Chagas disease is found mainly in endemic areas of 21 continental Latin American countries, where it has been mostly transmitted to humans by contact with feces or urine of triatomine bugs (vector-borne), known as 'kissing bugs,' among many other popular names, depending on the geographical area. The infection has been increasingly detected in the United States of America, Canada, and many European and some African, Eastern Mediterranean, and Western Pacific countries. T. cruzi parasites are mainly transmitted by contact with feces or urine of infected blood-sucking triatomine bugs. These bugs typically live in the wall or roof cracks of homes and peri domiciliary structures, such as: chicken coops, pens, and warehouses, in rural or suburban areas. Normally they hide during the day and become active at night when they feed on animal blood, including human blood. They usually bite an exposed area of skin such as the face (hence its common name, kissing bug), and the bug defecates or urinates close to the bite. The parasites enter the body when the person instinctively smears the bug’s feces or urine into the bite, other skin breaks, or the eyes or the mouth (World Health Organization, 2022a).
Symptoms
Chagas disease presents in two phases. The initial acute phase lasts for about two months after infection. During the acute phase, a high number of parasites circulate in the blood, but in most cases the symptoms are absent or mild and unspecific. In less than 50% of people bitten by a triatomine bug, characteristic first visible signs can be a skin lesion or a purplish swelling of the lids of one eye. Additionally, they can present fever, aching head, enlarged lymph glands, pallor, muscle pain, difficulty in breathing, swelling, and abdominal or chest pain. During the chronic phase, the parasites are hidden mainly in the heart and digestive muscle. One to three decades later, up to 30% of patients suffer from cardiac disorders and up to 10% suffer from digestive (typically growth of the esophagus or colon), neurological, or mixed alterations. In later years the infection in those patients can cause the destruction of the heart muscle and nervous system, consequent cardiac arrhythmias or progressive heart failure, and sudden death. Trypanosoma cruzi infection is able to be cured if treatment is initiated soon after infection (World Health Organization, 2022a).
Controls
There is no vaccine to prevent Chagas disease. Vector control has been the most effective method of prevention in Latin America. Prevention methods include spraying of dwellings and surrounding areas with residual insecticides, house improvements and house cleanliness to prevent vector infestation, personal preventive measures such as bed nets, good hygiene practices in food preparation, transportation, storage, and consumption, development and training of education materials for the community (World Health Organization, 2022a).
Spraying of dwellings and surrounding areas with residual insecticides, house improvements and house cleanliness to prevent vector infestation, personal preventive measures like bednets, good hygiene practices in food preparation, transportation, storage, and consumption, development and training of education materials for the community.
Ebola
Basic Information
Ebola virus disease (EVD), formerly known as Ebola hemorrhagic fever, is a rare but severe and often deadly fatal illness in humans. The virus is transmitted to people from wild animals and spreads in the human population through human-to-human transmission. The average EVD case fatality rate is around 50%. Case fatality rates have varied from 25% to 90% in past outbreaks. It is thought that fruit bats of the Pteropodidae family are natural Ebola virus hosts. Ebola is introduced into the human population through close contact with the blood, secretions, organs, or other bodily fluids of infected animals such as fruit bats, chimpanzees, gorillas, monkeys, forest antelope, or porcupines found ill or dead or in the rainforest. Health-care workers have frequently been infected while treating patients with suspected or confirmed EVD. This occurs through close contact with patients when infection control precautions are not strictly practiced. Ebola then spreads through human-to-human transmission via direct contact with blood or body fluids of a person who is sick with or has died from Ebola or objects that have been contaminated with body fluids (like blood, feces, vomit) from a person sick with Ebola. Burial ceremonies that involve direct contact with the body of the deceased can also contribute to the transmission of Ebola (World Health Organization, 2021a).
Symptoms
The Ebola virus causes an acute, serious illness which is often deadly if untreated. People remain infectious as long as their blood contains the virus. The incubation period is from 2–21 days. A person infected with Ebola cannot spread the disease until they develop symptoms. Symptoms of EVD can be sudden and include fever, tiredness, muscle pain, aching head, and sore throat. These symptoms are followed by vomiting, diarrhea, rash, impaired kidney and liver function, internal and external bleeding (for example, oozing from the gums, or blood in the stools) (World Health Organization, 2021a).
Controls
Community engagement is key to successfully controlling outbreaks. Good outbreak control relies on applying a package of interventions; namely case management, infection prevention and control practices, surveillance and contact tracing, a good laboratory service, safe and dignified burials, and working together to make a difference. Vaccines to protect against Ebola have been developed and have been used to help control the spread of Ebola outbreaks in Guinea and in the Democratic Republic of the Congo (DRC) (World Health Organization, 2021a).
Applying a package for interventions: case management, infection prevention and control practices, surveillance and contact tracing a good laboratory service, safe and dignified burials, and social mobilization.
Rabies-Dogs
Basic Information
Rabies is a vaccine-preventable zoonotic viral disease (World Health Organization, 2021b). Rabies is estimated to cause 59 000 human deaths annually in over 150 countries, with 95% of cases occurring in Africa and Asia (World Health Organization, a). People are usually infected following a deep bite or scratch from an animal with rabies. Dogs are the main source of human rabies deaths, contributing up to 99% of all rabies cases in humans. However, human deaths have followed exposure to foxes, raccoons, skunks, jackals, and mongooses (World Health Organization, 2021b).
Symptoms
Early symptoms of a rabies infection can include a fever with pain and unusual or unexplained tingling, piercing or burning sensation at the wound site. In later states, the virus spreads to the central nervous system, causing deadly inflammation of the brain and spinal cord. The incubation period of the disease can vary from one week to one year, though it is typically 2–3 months (World Health Organization, a). Once clinical symptoms appear, rabies is virtually 100% deadly (World Health Organization, 2021b).
There are two forms of the disease. The two types of rabies show different symptoms. Furious rabies causes signs of hyperactivity, excitable behaviour, hydrophobia (fear of water) and sometimes aerophobia (fear of drafts or of fresh air). Death occurs after a few days due to cardio-respiratory arrest. Paralytic rabies, which accounts for about 20% of the total number of human cases, runs a less dramatic and usually longer course than the furious form. Muscles gradually become paralyzed, starting at the site of the bite or scratch. A coma slowly develops and eventually death occurs (World Health Organization, a).
Controls
Successful rabies control programs are comprised of three pillars: Eliminating rabies in dogs, Awareness on rabies and preventing dog bites, and Immunization of people. Vaccinating dogs is the most cost-effective strategy for preventing rabies in people. Education on dog behavior and bite prevention for both children and adults is an essential extension of a rabies vaccination program and can decrease the occurrence of human rabies. If a person is bit by a dog with rabies, they should immediately and thoroughly flush and wash the wound for a minimum of 15 minutes with soap and water, detergent, or other substances that remove and kill the rabies virus. This should be followed by an effective rabies vaccine. The same vaccine that is used to immunize people after an exposure can also be used before exposure to rabies (World Health Organization, 2021b).
Mass vaccination of dogs, community participation; education, public awareness and access to mass vaccination of dogs; and access to post-bite treatment.
Snails-Schistosomiasis
Basic Information
Schistosomiasis is an acute and chronic parasitic disease caused by blood flukes (trematode worms). Estimates show that at least 236.6 million people required preventive treatment in 2019 and has been reported from 78 countries. It is estimated that at least 90% of those requiring treatment for schistosomiasis live in Africa. People become infected when larval forms of the parasite are released by freshwater snails and penetrate the skin during contact with infested water. People are infected during routine agricultural, domestic, occupational, and recreational activities which expose them to the infested water. Lack of hygiene and certain play habits of school-aged children such as swimming or fishing in infested water make them especially vulnerable to infection. In the body, the larvae develop into adult schistosomes. Adult worms live in the blood vessels where the females release eggs. Some of the eggs are passed out of the body in the feces or urine to continue the parasite’s life cycle. Others become trapped in body tissues, causing immune reactions and progressive damage to organs (World Health Organization, 2022g).
Symptoms
In children, schistosomiasis causes anemia, stunted growth, and reduced ability to learn, although its effects are usually reversible with treatment. Chronic schistosomiasis can affect people’s ability to work and, in some cases, result in death.
Intestinal schistosomiasis can result in abdominal pain, diarrhea, and blood in the stool. Liver growth enlargement is common in advanced cases and is frequently associated with an accumulation of fluid in the peritoneal cavity and hypertension of the abdominal blood vessels. In such cases there may also be growth of the spleen.
Urogenital schistosomiasis is shown by the classic symptom of hematuria (blood in urine). Fibrosis of the bladder and ureter, and kidney damage are sometimes diagnosed in advanced cases. Bladder cancer is another possible complication in the later stages (World Health Organization, 2022g).
Controls
The control of schistosomiasis is based on large-scale treatment of at-risk population groups, access to safe water, improved sanitation, hygiene education, and snail control. Groups targeted for treatment include pre-school-aged children, school-aged children in endemic areas, adults considered to be at risk in endemic areas, and people with occupations involving contact with infested water, such as fishermen, farmers, irrigation workers, and women whose domestic tasks bring them in contact with infested water and entire communities living in highly endemic areas. Praziquantel is the recommended treatment against all forms of schistosomiasis. It is effective, safe, and low-cost. Even though re-infection may occur after treatment, the risk of developing severe disease is diminished and even reversed when treatment is initiated and repeated in childhood (World Health Organization, 2022g).
Large-scale treatment with praziquantel of at-risk population groups, access to safe water, improved sanitation, hygiene education, and snail control.
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