What disease is caused by Giardia lamblia?

Giardia lamblia is a parasitic microorganism that is the causative agent of giardiasis, commonly known as 'beaver fever'. This infection is typically transmitted through the ingestion of contaminated water, particularly water that has been contaminated with fecal matter from wildlife, including beavers. Symptoms of giardiasis can include diarrhea, abdominal cramps, and nausea.

Contaminated drinking water is a significant public health concern, and understanding the transmission method is crucial for preventing outbreaks. The name 'beaver fever' arises because beavers are known carriers of the parasite, which can be found in the water sources where they live.

The other listed diseases are caused by different pathogens. Pneumonia can be caused by various bacteria and viruses, but it is unrelated to Giardia lamblia. Typhoid fever is caused by Salmonella typhi, a completely different bacterium, while dengue fever is a viral illness transmitted by mosquitoes, having no relation to Giardia lamblia at all. Therefore, the correct identification of giardiasis as 'beaver fever' highlights the specific pathogen and its mode of transmission, emphasizing the importance of water safety and sanitation.