Question

Which of the following diseases does not involve an arthropod vector? a. schistosomiasis b. malaria c. Chagas disease d. babesiosis

Short answer

Schistosomiasis

Step-by-step solution

Understanding Arthropod Vectors

Arthropod vectors are organisms such as insects or arachnids that transmit pathogens. Common arthropods include mosquitoes, ticks, and fleas.

Identify Diseases Involving Arthropod Vectors

List each disease and determine if it involves an arthropod vector.

Malaria

Malaria is transmitted by mosquitoes, specifically the Anopheles species. Therefore, it involves an arthropod vector.

Chagas Disease

Chagas disease is transmitted by the triatomine bug, an arthropod. Thus, it involves an arthropod vector.

Babesiosis

Babesiosis is transmitted by ticks, another type of arthropod, involving an arthropod vector.

Schistosomiasis

Schistosomiasis is caused by parasitic worms and is transmitted through contact with contaminated freshwater. It does not involve an arthropod vector.

Conclusion

Among the listed diseases, schistosomiasis is the only one that does not involve an arthropod vector.

Key concepts

Mosquito-borne diseases

Mosquito-borne diseases are illnesses that are transmitted to humans through the bite of an infected mosquito. These diseases are prevalent in tropical and subtropical regions around the world. The most common mosquito-borne diseases include:

• Malaria: Caused by Plasmodium parasites and transmitted by Anopheles mosquitoes. Symptoms include fever, chills, and flu-like illness. It can be fatal if not treated.
• Dengue: Caused by the dengue virus and transmitted by Aedes mosquitoes. Symptoms include high fever, severe headache, pain behind the eyes, joint pain, and rash.
• Zika: Caused by the Zika virus and transmitted by Aedes mosquitoes. It can cause fever, rash, joint pain, and conjunctivitis, and is particularly dangerous for pregnant women as it can cause birth defects.
• Yellow Fever: Caused by the yellow fever virus and transmitted by Aedes and Haemagogus mosquitoes. Symptoms range from fever and chills to severe disease with bleeding, jaundice, and organ failure.

To prevent mosquito-borne diseases, individuals should use insect repellent, wear protective clothing, and eliminate standing water where mosquitoes breed.

Tick-borne diseases

Tick-borne diseases are infections spread by ticks. These tiny arachnids attach themselves to the skin of animals and humans, feeding on their blood and potentially transmitting harmful pathogens. Common tick-borne diseases include:

• Lyme Disease: Caused by the bacterium Borrelia burgdorferi and transmitted by Ixodes ticks. Symptoms include fever, headache, fatigue, and a characteristic bull's-eye skin rash. If untreated, it can spread to joints, the heart, and the nervous system.
• Rocky Mountain Spotted Fever: Caused by the bacterium Rickettsia rickettsii and transmitted by several tick species. Symptoms include fever, rash, and headache, and it can be severe or even fatal if not treated promptly.
• Babesiosis: Caused by Babesia parasites and transmitted by Ixodes ticks. Symptoms range from mild to severe and include fever, chills, sweats, headache, body aches, loss of appetite, nausea, and fatigue.

Preventing tick bites involves avoiding grassy and wooded areas, using insect repellent, wearing long sleeves and pants, and performing thorough tick checks after spending time outdoors.

Vector-borne diseases

Vector-borne diseases are transmitted by vectors, which are living organisms that can transfer infectious pathogens between humans or from animals to humans. The most common vectors include mosquitoes and ticks. Notable vector-borne diseases are:

• Malaria: Transmitted by Anopheles mosquitoes.
• Dengue Fever: Transmitted by Aedes mosquitoes.
• Lyme Disease: Transmitted by Ixodes ticks.
• Chagas Disease: Transmitted by triatomine bugs, which are also arthropods.

Vector control is essential in preventing these diseases. This includes using insect repellents, environmental management to reduce vector breeding sites, insecticide-treated bed nets, and public health education about avoiding vector bites.

Schistosomiasis transmission

Schistosomiasis is a disease caused by parasitic worms called schistosomes. It is not transmitted by arthropod vectors like mosquitoes or ticks, but through direct contact with contaminated freshwater. The life cycle of schistosomes involves:

• Eggs: Released from infected humans through urine or feces into water sources.
• Miracidia: Hatch from eggs and infect certain species of freshwater snails.
• Cercariae: Develop inside the snails and are released into the water. They can penetrate human skin upon contact.
• Adult worms: Mature in human blood vessels and produce eggs that continue the cycle.

Symptoms of schistosomiasis include rash or itchy skin, followed by fever, chills, cough, and muscle aches. Chronic infection can cause liver damage, kidney failure, infertility, or bladder cancer. Prevention involves avoiding swimming in contaminated water, improving sanitation, and community health education.