module 8 gch

Neglected tropical diseases (NTD’s)

are infectious diseases that primarily occur in the poorest regions of the world and have not historically been a priority for global policy makers, funding agencies, or pharmaceutical companies. The big three infectious diseases—- HIV, tuberculosis, and malaria have received the bulk of global infectious disease attention and financing in recent decades

parasite

is an organism that survives by living in or on a host organism. Parasites are eukaryotes that consist of a complex cell or cells that have a membrane-bound nucleus

intermediate host

is an animal host in which an immature parasite develops but does not reach sexual maturity. Some parasites have one intermediate host, and some have two different intermediate hosts

definitive host

is the animal host in which a parasite reaches sexual maturity and reproduces

protozoan

is a single celled organism that has animal-like characteristics. Some protozoa are free living, and some are parasitic

helminth

is a multicellular parasitic worm. Some helminths that live inside the human body are microscopic, but others grow to be several inches long or even several feet in length as they mature in the human body. Hemlinths usually produce eggs or offspring that are expelled from the body of the host so that they will infect other hosts rather than competing with the parent for resources

nematode

or roundworm, is a cylindrically shaped worm with a simple digestive system that extends the full length of the worm from the mouth to the anus. There are many types of Nematodes that have humans as hosts, including filarial worms, guinea worms, hookworms, pinworms, round worms, threaworms and whipworms

cestode

or tapeworm, is a ribbon-like worm consisting of a mouthpiece and numerous flat segments. Cestodes have no mouth or gut. They absorb nutrients from their hosts through a body-covering tissue called tegument.

trematode

or fluke, is a flat, unsegmented worm that typically has a complex life cycle involving two different animal hosts. Trematodes have oral and ventral suckers but only a blind gut and not a full digestive systems. They absorb nutrients through tegument.

Malaria

is a mosquito-borne parasitic infection with Plasmodim protozoa that can cause cyclic fevers, anemia, neurological complications, and death

Plasmodium

Protozoans in the Plasmodium genus cause malaria and they have complex life cycles involving both sexual and asexual reproduction within the red blood cells of human hosts. P. falciparum P.vivax P. malariae P.ovale and P.knowlesi

Falciparum malaria

is an infection with the species of plasmodium that is most likely to cause life-threatening disease. Almost 99% of malaria cases in sub saharan africa are caused by P. falciparum

Vector

is an organism (usually non-vertebrate) that transmits a pathogen to another organism

Anopheles mosquitoes

are the vector that transmits malaria-causing parasites to humans

Malarial anemia

is the destruction of a so many red blood cells by malaria-causing parasites that the body cannot adequately transport oxygen through the bloodstream

Cerebral malaria

a neurological complication of plasmodium infection that is characterized by seizures and coma. If children survive cerebral malaria, they may have permanent brain damages and learning disabilities

Artemisinin-based combination therapy (ACT)

is malaria treatment that combines at least two different antimalarial drugs, one of which is an artemisinin-based drug. For example, ACT could be in the form of artemether plus lumefantrine, artesunate plus amodiaquine, or dihyrdoarteminisinin plus piperaquine

parasitemia

is the presence of parasites in the blood

rapid diagnostic test (RDI)

is a test that can quickly detect the presence of a pathogen or markers for a pathogen in blood or another body fluid

intermittent preventive treatment (IPT)

is the routine distribution of anti-infective medications to vulnerable people so that they maintain therapeutic drug levels in their blood during times of high risk for disease

autochothonous

Case of malaria or other infection diseases that are locally acquired rather than imported are called autochothonous cases

persistent organic pollutant (POP)

is an organic compound that does not degrade easily

DDT (dichloro-diphenyl-trichloroethane)

is a POP that used to be widely used as an agricultural pesticide. The highest concentrations of DDT occur in animals higher up in the food chain

Indoor residual spraying (IRS)

is the application of long-lasting insecticides to walls and other surfaces where mosquitoes might rest. The IRS sticks to the walls so that it only has to be reapplied once or twice a year

insecticide treated net (ITN)

is a mesh sheet dipped in insecticides and then hung over a bed so that it provides a barrier between sleeping humans and mosquitoes while also killing any mosquitoes that land on it

long-lasting insecticidal net

is an ITN that has been impregnated with a pesticide that remains effective for 2 years or longer before requiring retreatment

DEET

is an effective insect repellent but it does not kill mosquitoes

dengue

is a mosquitoe-borne viral infection that is sometimes called breakbonee fever because it can cause severe joint and muscle pain. There are four distinct serotypes of dengue fever

Aedes mosquitoes

a genus of mosquito that has black and white stripes on its body and legs, thrives in urban areas, and can be an aggressive day biter

vector control

interventions reduce the size and density of arthropod populations

arthropod

is an insect or an arachnid

vector-borne infection

is one in which the pathogen is transmitted to humans via an arthropod

cycle of transmission

describes how an infectious agent passes between different species. Some species have human-human-human cycles like measles and others have animal-animal-animal cycles that occasionally transmit to humans like rabies

arbovirus

short for arthropod born virus, is a virus transmitted to humans by an arthropod. All arboviruses are viral infections

chikungunya

is an aedes-transmitted arbovirus that can cause long-term disability. from joint pain. most cases of chikungunya are symptomatic

yellow fever

is a vaccine preventable mosquito-borne viral infection that causes the skin and eyes of infected people to become yellow due to jaundice

west nile virus

is an arbovrius that has become endemic to the united states and can cause encephalitis. The virus typically cycles between mosquitoes and birds, but it occassionally affects humans, Most people who become infected with west nile virus have no symptoms or only mild symptoms, while a small percentage may experience serious neurological complications

culex mosquitoes

a genus of mosquito that deposits rafts of 100 or more eggs on water rather than laying eggs singly

zika virus

is a mosquito-borne viral infection that is usually asymptomatic but has been linked to an increased risk of microcephaly in babies born to women who contract the virus during the pregnancy

microcephaly

an abnormally small head that is a sign of aberrant brain development

rift valley fever

is a zoonotic arbovirus infection that can cause outbreaks of pregnancy loss in livestock herds. Most humans who contract rift valley fever virus have a mild infection, but a small percentage develop vision loss, meningocephalitis, and hemorrhagic fever

lymphatic filariasis

is a mosquito-borne helminth infection that can block lymph nodes and cause fluid buildup in affected legs and other body parts

lymphedema

is the swelling of body parts due to retained lymph fluid in the tissues

elephantiasis

in which the skin of an affected limb thickens and develops a coarse texture similar to that of an elephant leg. Elephantiasis can also be caused by podoconiosis, which is thought to result from a genetic predisposition to have inflammatoru reaction when bare feet are chronically exposed

hydrocele

lymphedema of the scrotum

preventative chemotherapy

is the use of a safe medicine as part of a public health strategy to prevent and control an infectious disease

mass drug administration (MDA)

is the distribution of preventative chemotherapy to large population groups at regular time intervals as part of strategies for preventing and controlling infectious diseases

onchocerciasis

also known as river blindness, is a fly-borne helminth infection that can cause blindness. Onchocerciasis is caused by onchocerca volvulus which is transmitted to humans by the bites of infected black flies from the simulium genus

schistosomiasis

is a blood fluke disease that can increase the risk of bladder cancer among people with chronic infection. Schistosoma are trematodes that cycle between snails and humans

reservoir

is the environmental home for an infectious agent

soil-transmitted helminth

also called a geohelminth, is a nematode infection contracted through contact with soil that contains feces mixed with worm eggs or larvae. Once the worms mature inside a human host, most STHs are intestinal parasites

asciariasis

is the most prevalent intestinal helminth infection, and people with the condition have long worms dwelling their small intestines. After a human swallows eggs from ascaris lumbricoides, the ingested larvae hatch in the small intestine , penetrate the intestinal wall, travel through the blood to the lungs where they may be coughed up and swallowed

trichuriasis

also known as whipworm, occurs when trichuris trichuria are residing in the large intestine. When the eggs that cause trichuriasis are swallowed, the eggs hatch in the small intestine

hookworm

is a helminth that latches onto the walls of the intestine. Both necator americanus and ancylostoma duodenale cause hookworm, and they are most often acquired by walking barefoot through contaminated soil

strongyloidiasis

sometimes called threadworm, is usually soil transmitted but has the capacity to reproduce entirely within a human host. Larvae is acquired through walking barefoot in contaminated soil

Chagas disease

is a trypanosome infection that can cause chronic heart and intestinal damage. Chagas disease is caused by T cruzi parasites, which are spread by triatomines that live in the cracks of walls and roofs of low-quality house in central and south america

trypanosomiasis (HAT)

is commonly called african sleeping sickness because it causes infected humans to fall into comas and die. HAT is caused by trypanosoma brucei, which is transmitted to animals and humans by the bites of infected tsetse flies

Leishmaniasis

is a sand fly transmitted protozoal disease that can cause disfigurement and death. The disease is caused by protozoa from a variety of species of the leishmania genus

leprosy/ hansens disease

is a chronic myobacterium infection that can cause nerve damage that leads to amputations. Leprosy was first described in ancient times as a disfiguring disease that caused its victims to become ostracized from their communities

buruli ulcer

is a mycobacterial infection that causes painless lesions that can become so deep that they extend from the skin to the underlying tendons and bones of the arms or legs. The wounds caused by mycobacterium ulcerans infection are often painless, even when the ulcer is large, because the bacteria release a necrotizing toxin called mycolactone

trachoma

is a bacterial eye infection that can lead to blindness in people who do not practice good facial hygiene. Chlamydia trachomatis bacteria are spread when eye and nose secretions are passed between people by person-person contact, shared clothes, and flies

SAFE strategy

which combines surgery to treat trichiasis, antibiotics to kill the bacteria, facial cleanliness encouraged by hygiene education, and environmental improvements to ensure reliable access to water and sanitation

Yaws

is the most prevalent endemic treponematosis, and it causes disfiguring skin lesions. If untreated, the infection can cause permanent disability by spreading to bone and cartilage

mycetoma

is a chronic granulomatous inflammatory disease of the subcutaneous tissue of the foot. People with mycetoma have swollen, disfigured feet that ooze pus

endoparasite

such as a protozoan or helminth, lives inside the body of its host

ectoparasite

such as louse or scabies, lives on the exterior surface of it’s hosts body

scabies

occurs when tiny mites burrow into the outer later of human skin between fingers, at the wrists, and in other locations, living and laying eggs at those sites. The immune response to this infestation causes intense itchiness, and the wounds created by the mites and scratching at the skin can lead to severe secondary bacterial infections

taeniasis

occurs when tapeworms that cycles between pigs or cattle and humans are living in human intestines. Pigs are the intermediate host for t. solium , and humans are the definitive host for the worm

cysteicercosis

is the disease caused by taenia solium forming cysts in the muscle tissue or in other parts of the body

neurocysticercosis

occurs when T. solium larvae, called cysterceri, trigger epileptic seizures and other problems associated with brain lesions

echinococcosis

is the disease caused when humans become the accidental host for a cyst-inducing tapeworm that usually matures in dogs. Two types of human disease

hydatid disease

which occurs when the larvae cause cysts to form in the liver and lungs. Alveolar echinococcosis is caused by E. multilocularis, which has a life cycle in which rodents are the intermediate host and foxes, coyotes, and dogs are the definitive hosts

Rabies

is a lethal zoonotic virus infection transmitted through the bites of infected mammals. Any mammal can contract rabies, including bats, and the virus circulates in wild animal populations on every continent except antarctica

Control

is the process of using public health interventions to reduce the incidence or prevalence of an adverse health condition to a substantially lower level within a community or a larger geopolitical area

Elimination

is the process of removing all risk of new infection in a defined geopolitical area. Elimination uses control measures to reduce the incidence of disease to 0 in a selected location

eradication

is the process of eliminating an infectious disease globally. Eradication is achieved when there is not risk of infection or disease anywhere in the world, even in the absence of immunization and other control measures

rinderpest

was a zoonotic disease that decimated cattle herds. The virus that caused the disease, a paramyxovirus related to the one that causes measles in humans, spread easily when animals had physical contact with one another

epizootic

is an outbreak in an animal population; epidemics occur among humans and epizootics occur among animals

smallpox

was a viral disease of humans that caused blisters to form all over the body and could cause death or permanent disability. The blisters first appeared on the face, then spread to the extremities and then the trunk

extinction

is the process of destroying all laboratory specimens of an eradicated pathogen so that there is no possibility of the pathogen reentering the human population

dracunculiasis or guinea worm disease

is a painful condition in which a long filarial helminth takes weeks to slowly emerge from its human host. People contract the guinea worm disease by drinking water that contains fleas called copepods that are infected with worm larvae. Stomach acids kill ingested copepods and release guinea worm larvae, which migrate into the abdominal cavity of the human and then in to the subcutaneous tissues, where they mature and reproduce

polio

also called poliomyelitis or infantile paralysis, is a viral infection that can attack the spinal cord and cause permanent paralysis. Poliovirus, which is in the enterovirus genus, is typically transmitted through fecal-oral transmission, such as when infants and children with dirty hands touch their mouths. No cure for polio but it is vaccine preventable

transmissability

is the ease with which an infectious agent is passed from an infected host to another individual

infectivity

is the capacity of an infectious agent to cause infection when a susceptible host without immunity to the infection acquired from prior infection or vaccination is exposed to the agent

pathogenicity

is the capacity of an infectious agent to cause disease in an infected host

virulence

is the ability of an infectious agent to cause severe disease or death in a host. A virulent infection often has a high case fatality rate because a sizable proportion of people who become ill from the infection will die

emerging infectious disease

is caused by an infection with a pathogen that has not previously caused severe disease in humans or is affected human populations in new ways

ebola virus disease

is a viral hemorrhagic fever caused by a filovirus that is transmitted through the body fluids of infected individuals

syndemic

occurs when two or more disease cluster within a population, in part due to social and structural conditions, and the interaction between the disease makes the health outcomes worse