Plasmodium Cycle, Hepatitis B Diagnosis and More Parasitic and Fungal Biology

Plasmodium Cycle

The Plasmodium cycle involves a single large number of forms that develop in some other intermediate hosts, including humans and mosquitoes.

Sporozoites are injected into the human host with the saliva of the mosquito during the first bite. Sporozoites introduced into the human liver invade hepatocytes, where they reproduce asexually.

Following this, the schizont (a multinucleated cell) ruptures, releasing about 100 to 200 merozoites into circulation, which can easily disseminate.

Human Blood Stage

The initial blood stage in humans begins with the formation of the trophozoite, a simple parasite inside the red blood cell. The trophozoite matures and forms another schizont, which initiates the blood cycle (rupture releases merozoites that infect new red blood cells).

Some trophozoites develop into the mature form called gametocytes, which may or may not be taken up by the mosquito. Gametocytes circulate in the blood.

If a mosquito bites an infected person with gametocytes, it ingests red blood cells containing gametocytes, initiating the next stage in the mosquito. In the mosquito stomach, the Plasmodium undergoes sexual reproduction, passing through the stages of macrogamete, oocyte and oocyst, until the oocyst ruptures, releasing sporozoites that migrate to the salivary glands and restart the cycle.

At this point the mosquito is fully infected and totally able to infect a human when it bites.

Diagnosis of Hepatitis B

Antigens:

• HBsAg (marker of replication)
• HBeAg (evolutionary marker of poor prognosis)

Antibodies:

• Anti-HBs (marker of immune protection)
• Anti-HBe (evolutionary marker of good prognosis)
• Anti-HBc IgG / IgM (markers of prevalence and acute infection)

Viral DNA: Plasma (marker of active infection)

Enveloped Viruses

Enveloped viruses are formed by remnants of the host cell membrane and viral proteins. They are labile to environmental factors. The membrane is modified during the cell's replication and budding, and lysis. They do not destroy the host cell. They cannot persist in humid environments and are inactivated in the gastrointestinal tract. They spread through transplants and transfusions. Immunologically, control of the cellular response is necessary and they may develop tables and inflammation, hypersensitivity.

Tapeworm Cycle

The solitary individual acquires infection after ingesting undercooked or raw pork containing cysticerci (larvae). Often there are no clinical symptoms; in some cases, vomiting, abdominal discomfort and diarrhea may occur.

Examination of the feces reveals the proglottids and the presence of eggs, similar to the two species of Taenia.

• Scolex: 4 suckers and 2 rows of hooks, the hook
• Gravid segment: Uterus with 7 to 13 branches.

Cysticercosis

Human infection with the larval stage of T. solium, the cysticerci, normally infects humans through ingestion of eggs or contaminated vegetables, causing autoinfection. If cysticerci remain in vital central nervous system areas, they can cause a serious disease: meningitis and convulsions. The larvae die and release antigenic and inflammatory products, which triggers marked immune reactions.

Certain oncogenic types of HPV are associated with integration of viral DNA into the host cell chromosome. This integration affects the expression of the E2 protein, which stops expressing E2 (a 48 kDa inactive protein), and the regulation over E1 is lost. At this point the virus can replicate productively. Expression of E6 and E7 increases, which causes the cell to lose differentiation. For example, E6 degrades and activates the p53 protein, and activates telomerase promoters. E7 inactivates the protective protein of the retinoblastoma (Rb) and other tumor suppressors.

Stages of Influenza

The clinical syndrome of influenza depends on the degree of immunity of the affected person. Complications can be asymptomatic or severe.

The incubation period is 1 to 4 days, with prodrome and headache, malaise, fever and myalgia, followed by intense and nonproductive cough. The illness typically lasts about 3 days, and full recovery occurs in 7 to 10 days.

In children, bronchiolitis, laryngotracheobronchitis may appear, and the virus can cause otitis media. Pneumonia may be a primary complication or a bacterial infection with secondary pneumonia (H. influenzae, S. aureus, S. pneumoniae). Other complications may occur.

Fungi Hyphae

Fungi are divided into two basic morphological types: vegetative and aerial hyphae. Hyphae are tubular filaments that branch, which can be coenocytic (non-septate and multinucleated) or septate (divided by cross-walls). The whole mass is called the mycelium. Vegetative hyphae are formed to absorb nutrients, and aerial hyphae grow above the surface. The latter form specialized structures or conidia, which serve to disperse the fungus. Some fungi are dimorphic.