He described canine filarial worm Dipetalonema reconditum, and demonstrated the parasite life cycle in fleas, Pulex irritans.

He was the first to describe and establish the life cycle of the human malarial parasite, Plasmodium falciparum, the most prevalent and deadliest species.

[3] For the 1902 Nobel Prize in Physiology or Medicine, he was nominated alongside French physician Charles Louis Alphonse Laveran, who discovered P. falciparum, and British army surgeon Ronald Ross.

Grassi, who demonstrated the complete route of transmission of human Plasmodium, and correctly identified the types of malarial parasite as well as the mosquito vector, Anopheles claviger, was denied.

[4] His father Luigi Grassi was a municipal official, and mother Costanza Mazzuchelli was a noted peasant of unusual intelligence.

Also in Catania he began to study entomology and wrote a student text "The Origin and Descent of Myriapods and Insects" in addition to scientific papers.

[6] He joined Angelo Celli, Amico Bignami, Giuseppe Bastianelli and Ettore Marchiafava, who were working on malaria in districts around Rome.

The group announced at the session of the Accademia dei Lincei on 4 December 1889 that a healthy man in a non-malarial zone had contracted tertian malaria after being bitten by an experimentally infected Anopheles claviger.

[9] In 1902, Grassi abandoned his study of malaria and began work on the sandfly responsible for Leishmaniasis (Phlebotomus papatasii) and on a serious insect pest of the grape vine (Phylloxera vastatrix).

He published his first report on the arrow worms in 1881 and a monograph in 1883 by which he described 14 new species and established that the animals are not related to molluscs and coelenterates, as then believed to be.

The notes of his observations La questione fillosserica in Italia (1904) influenced the Italian Ministry of Agriculture, which eventually requested him to do an exhaustive study of this subject.

[10] In 1876, Grassi investigated his native hometown Rovellasca for the high mortality of cats and discovered that they were heavily infected with the nematode (roundworm) Dochmius balsami.

In 1878, while still a student at the University of Pavia, he made the first description of Ancylostoma caninum, a roundworm that causes ancylostomiasis in cats, after identifying the eggs from the faeces of infected individuals.

In 1890 he, with Salvatore Calandruccio, described Dipetalonema reconditum, a non-pathogenic filarial worm of dogs, and showed that the parasite completed its development in human fleas, Pulex irritans.

[4] The amoebas are later established as commensal parasites that contribute to the healthy environment (human microbiome) of the gastrointestinal tract,[21] and closely related to the pathogenic species, E.

[6] The first malarial parasite of humans was discovered by French Army physician Charles Louis Alphonse Laveran, while working at Bône Hospital (now Annaba in Algeria), in 1880.

[25] Laveran gave the name Oscillaria malariae, which was ultimately changed to Plasmodium falciparum by the International Commission on Zoological Nomenclature (ICZN) in 1954.

[1][18] Moving to the Sapienza University of Rome in 1895, Grassi joined established malariologists Bignami and Bastianelli to further investigate on malaria, most importantly, on how it was transmitted.

[6] Grassi was able to obtain malaria samples easily from the Hospital of the Holy Spirit (Ospedale di Santo Spirito in Sassia).

[9] With Bignami and Bastianelli, Grassi experimented with different mosquitos to see if they could take up live parasites after feeding on the blood of malarial individuals.

With careful experimentation, he used himself as a test subject (control) by covering himself with an iron net inside the same room where the mosquitos were released.

The most important observation was oocysts (from which human infective forms, sporozoa, would eventually emerge) that indicated the successful growth of the parasite in the mosquitos.

Grassi, Bignami and Bastianelli reported the discovery to the Accademia dei Lincei on 6 November 1898, and was formally read before the meeting of the academy on 4 December.

[9] Grassi's comprehensive monograph on the identity and impact of different malarial parasites, Studi di uno Zoologo Sulla Malaria published in 1900 is as relevant today as it was in his time.

In fact, in 1919 he identified three typical malaria-prevalent localities which were not affected by malaria in the same way: the gardens of Schito near Naples, Massarosa in Tuscany, and Alberone in Lombardia.

"[4] In 1921, after repeated assessment, he became convinced that there were races of the same mosquito species which were morphologically indistinguishable but do not bite humans and therefore did not play a role as vectors.

In 1918, he established what he called "malaria observatory" at Fiumicino where he could monitor the extent of mosquitos migrating and biting humans in the residential areas.

At the time, those who advocated the mosquito eradication method believed that it would be sufficient to control the insect breeding places within the human habitations, such as the marsh area in case of Fiumicino.

For Fiumicino, Grassi designed an embankment system for the marsh area to prevent mosquito breeding and that could be utilised for irrigation during summer.

[Translated as: IN THIS HOME OF HIS ANCESTORS/27 MARCH 1854 WAS BORN/BATTISTA GRASSI/PHYSICIAN AND EXCELLENT SCIENTIST AND PHILOSOPHER/ CONTENTIONS TO BIOLOGY /HE TOOK ARMS AGAINST MARSH FEVER/UNSUCCESSFULLY FOUGHT FOR CENTURIES/DIED IN ROME ON 4 MAY 1925/WANTED TO BE BURIED AT FIUMICINO/BETWEEN THE HUMBLE WORKERS OF MAREMMA AND MARSH/OF WHICH HE HAD STARTED THE REDEMPTION/HIS TOWNSMEN DEDICATE/TOMBSTONE AND HONOURED/IN THE CENTENARY OF HIS BIRTH /WHEN THE WORLD COMES TRUE/HIS HUMAN DREAM OF REDEMPTION/FROM THE AGE-OLD SCOURGE OF MALARIA/27 MARCH 1954] Grassi authored more than 250 scientific papers and, in collaboration with his students and colleagues, wrote another 100.