**12. Discussion**

The pattern alternation of sexual and asexual reproduction which may seem confusing at first is a very common pattern in parasite species. The evolutionary advantages of this type of life cycle were recognized by Gregor Mendel.

Under favorable conditions asexual reproduction is superior to sexual as the parent is well adapted to its environment and its descendents share these genes. Transferring to a new host or in times of stress, sexual reproduction is generally superior as this produces a shuffling of genes which on average at a population level will produce individuals better adapted to the new environment.

Given that this parasite spends part of its life cycle in two different hosts it must use a proportion of its available resources within each host. The proportion utilized is currently unknown. Empirical estimates of this parameter are desirable for modeling of its life cycle.

#### **Dormant Form**

#### *Plasmodium falciparum malaria*

A report of *P. falciparum* malaria in a patient with sickle cell anemia four years after exposure to the parasite has been published . A second report that *P. falciparum* malaria had become symptomatic eight years after leaving an endemic area has also been published.[21]

A third case of an apparent recurrence nine years after leaving an endemic area of *P.*  falciparum malaria has now been reported. A fourth case of recurrence in a patient with lung cancer has been reported. Two cases in pregnant woman both from Africa but who had not lived there for over a year have been reported.

A case of congenital malaria due to both *P. falciparum* and *P. malariae* has been reported in a child born to a woman from Ghana, a malaria endemic area, despite the mother having emigrated to Austria eighteen months before and never having returned. A second case of congenital malaria in twins due to *P. falciparum* has been reported. The mother had left Togo 14 months before the diagnosis, had not returned in the interim and was never diagnosed with malaria during pregnancy.[24,25]

It seems that at least occasionally *P. falciparum* has a dormant stage. If this is in fact the case, eradication or control of this organism may be more difficult than previously believed.[25,26]
