Sunday, May 19, 2024

Case of the Week 748

 We are now shifting gears from microfilariae to something completely different. These organisms were found in a small pond in Minnesota. What are they? Be as specific as possible.

Saturday, May 18, 2024

Answer to Case 748

Answer to Parasite Case of the Week 748: Culicine mosquito larvae and pupae.

The mosquito life cycle consists of four stages: egg, larva, pupa, and adult. Larvae and pupae are aquatic, so water source control is an important component of mosquito control programs. The larvae (commonly called wrigglers) feed on microorganisms such as plankton, algae, bacteria, and fungi; some even eat other mosquito larvae! 

Culicine larvae (including Culex and Aedes species) breathe oxygen through a respiratory siphon and may be seen 'hanging' from the surface of the water. Anopheline larvae (Anopheles species), in comparison, do not have siphons. They lie horizontally to the water surface and breathe through respiratory spiracles. 

You can further identify mosquito larvae using keys such as the CDC Pictorial keys for arthropods, reptiles, birds, and mammals of public health significance (page 138).

Mosquito pupae (commonly called tumblers) are also seen in this case. They do not eat and have a rapid tumbling motility which allows them to avoid predators. They breathe through two tubes from the surface of the water. 

If allowed to mature, the adult mosquito will emerge from the pupal case within a few days. Female mosquitoes from most species will seek out a blood meal to support egg production, and are capable of transmitting a variety of viruses and parasites to humans in the process.  Lymphatic filariasis and malaria are important parasitic diseases transmitted by mosquitoes.

Wednesday, May 1, 2024

Case of the Week 747

Welcome back to the very end of our microfilariae block with Idzi Potters and the Institute of Tropical Medicine, Antwerp! We are going to end with a very special and somewhat unusual case. The patient is an elderly man with recent travel to Senegal who had a 10-cm round worm removed from the conjunctiva of his left eye (!). Blood obtained around the same time revealed the following microfilariae measuring >200 micrometers long: 

What is your diagnosis?