Vector Borne Diseases

public health emergency of international concern

-Declared by World Health Organization (WHO) in 2016 -Based on the suspected link between Zika virus infection and congenital malformations, neurologic syndromes

transmission blocking vaccines (TBV)

-Mosquito stage malaria vaccines are designed to induce an immune response in the human host -Antibodies generated by TBVs would be transferred to a mosquito during a blood meal (blocking sexual reproduction within mosquito and preventing it) -Parasite can not develop in mosquito gut, transmission of parasite is blocked (to next human host) doesn't protect individual from malaria, less popular PROS: few parasites to kill protecting community with less parasites won't pass disease to others CONS: doesn't protect individual who was infected with malaria little protection of liver

prevention of zika virus

-No vaccine -Avoid mosquito bites: insect repellent -Condoms (reduce risk of Zika from sexual transmission) Travel advisories

vector control

-Survey and map presence of Aedes aegypti and Aedes albopictus within the state -Use larvicides in containers and bodies of water that cannot be removed or dumped. -Mosquito control in area (indoor and outdoor spraying) -Community wide measures (Naled: aerial spraying): Done in Miami, Tampa, and New Orleans (after Hurricane Katrina) *European Union bans the use of Naled: "Potential and unacceptable risk to human health" genetic mutants put into the zika heavily population, goal is when mosquitoes have sex, male mates with female and offspring die. pass lethal gene to females

transmission of malaria

1. Plasmodium is transmitted in the saliva of female Anopheles mosquitoes, which injects saliva to prevent blood clotting when they feed on the blood of a person. 2. When a mosquito bites an infected person, Plasmodium is taken up into the mosquito's body and eventually reaches the salivary glands. 3. Mosquitoes are the vector for malaria. Transmitted by vector: anopheles mosquito Only female mosquitoes bite, why? Females need blood to lay their eggs. The adult mosquito has a life span of about 2 weeks. After the female mates, she searches for blood. This blood is a good source of protein for her eggs. Malaria is not contagious. Can not be spread through direct contact (ie sexual transmission, droplet spread). Since parasite is found in red blood cells, it can be passed via blood transfusion (rare), or passed from mother to unborn child

diagnosis and treatment

A blood or urine test can confirm a Zika infection (molecular tests: Check for viral RNA). ELISA used to detect antibodies to virus (follow up) Treatment: -Treat symptoms -Virus stays in blood stream for 2 weeks

ACT-Artemisnin-based combination therapy

Artemisinins (isolated from plant-herb used in Chinese traditional medicine)-used in combination therapy less chance of drug resistance if use multidrug approach Monotherapy is discouraged Drug resistance has been observed in Cambodia and parts of Thailand (Science 2010)

prevention of malaria

Avoid mosquito bites -Mosquito nets -Insect repellant -Insecticide-treated Bed nets ($5) -Prophylactic drugs must look at geography and age to see what drug therapy works

discovery of malarial parasite

Dr. Laveran: discovery of malarial parasite 1880, noble prize 1907 Dr. Ross: malaria parasites could be transmitted from infected patients to mosquitoes in 1897, noble prize 1902

causes of zika virus

Enveloped virus, RNA genome: First identified in 1947 (Zika forest, Uganda) Transmission: -spread from pregnant mother to fetus -mosquito (Aedes species) -sexual transmission -blood transfusion (very likely but not confirmed)

symptoms of malaria (blood stage parasite)

Flu-like (fever, chills, headache) when detected, symptoms will stop when it hides in red blood cells then when detected will cycle in symptoms of fever Nausea, vomiting may occur May cause anemia and jaundice due to loss of red blood cells Infection with Plasmodium falciparum if not treated can cause kidney failure, coma, death (ability of parasite to digest hemoglobin and not suffer from toxins-heme)

plasmodia life cycle

Life Cycle of Malaria parasite animation sporozoites: infect liver cells merozoites: infect red blood cells. (can hide from immune system in red blood cell) some merozoites develop into gametocytes (within mosquito) gameotcytes: develop into gametes within mosquito gut. gametes fuse to form zygote which develop into sporozoites. sporozoites travel to salivary gland of mosquito. cycle repeats (new mosquito takes in gametocytes) then develop into sporozoites

symptoms of zika virus

Many people: no symptoms, or mild Major concern: pregnant woman- can cause microcephaly and other birth defects children have smaller heads with a ton of disorders when born

TBV

Pros: -Fewer parasites to kill -Protection for community at large, mosquito that bites vaccinated person will not pass disease to others -Combination therapy (Given with RTS/S)-benefit to recipient and community. RTS/S targets parasite in liver stage Cons: -Vaccinated person can still get sick -Development of vaccine very difficult (Plasmodium proteins are difficult to make) -Has to be cheap, safe, and 100% effective -Side effects (already observed in clinical trials)

Quinine (early 17th century)

Quinine is a white naturally occurring alkaloid (compound containing nitrogen) in a crystalline form. We get Quinine from the bark of the cinchona tree, a tree that is found in Andes mountains in South America. No other tree naturally produces this compound. The bark of this tree is removed in strips. This is then dried and powdered to use for its medicinal properties.

malaria vaccine: pilot program

RTS,S is a malaria vaccine that has been developed through a partnership between GlaxoSmithKline Biologicals (GSK) and the PATH Malaria Vaccine Initiative (MVI) RTS,S acts against Plasmodium falciparum (targets liver stage), the most deadly malaria parasite globally, and the most prevalent in Africa (attempt to prevent liver stage involvement, don't know for sure) -Pilot program (3 countries in sub-Saharan Africa)-2018 Phase 3 clinical trials: 15,000 infants, 7 countries (sub-Saharan Africa) -Infants (at 6, 10, 14 wks), and older (1st dose between 5 and 17 months). -Vaccine efficacy against clinical malaria was 39% over the full duration of the trial (older group), 27% for infants, with 4th dose

plasmodia

The vector is the vehicle that transmits the microorganism. The mosquito does not suffer from the parasite invasion The malarial parasite is a plasmodium An Anopheles mosquito carrying malaria-causing parasites feeds on a human. The parasites carry out their life cycle. mosquito is vector for disease. malaria is caused by the plasmodium. mosquito transmits parasite

malaria stats (2017)

There were an estimated 219 million cases of malaria in 87 countries. The estimated number of malaria deaths stood at 435,000 Nearly half of the world's population was at risk of malaria. Most malaria cases and deaths occur in sub-Saharan Africa. Children under 5 years of age are the most vulnerable group affected by malaria; in 2017, they accounted for 61% (266,000) of all malaria deaths worldwide.

distribution of malaria

particular mosquito, where it can thrive and where a parasite can grow (complete part of life cycle in mosquito) depends on environmental factors distribution can change as temperature can shift (temperate regions) malaria parasite needs to complete it's growth cycle in mosquito temperatures below 60 degrees F are bad for parasite

Zika virus

transmitted by: Aedes Mosquito