Abstract
Background:
Humans and animals who have an acute case of diarrhea can be infected with Cryptosporidium spp. Within the category of water-borne disease, it is a zoonotic disease. The zoonotic disease Cryptosporidium is among the several pathogens carried by wild rats (Rattus spp.). The risk of spreading this disease is rather significant in urban environments because rats are often close to people.

Aim:
This study aims to detect Cryptosporidium spp. infection in wild rats in Surabaya, East Java, Indonesia.

Methods:
Through necropsy, a total of 100 wild rats' intestines were sampled for feces. Microscopic observation of the presence of Cryptosporidium was carried out using the float test with a combination of Ziehl Neelsen staining. Molecular detection of Cryptosporidium spp. positive results used the Cryptosporidium oocyst wall protein (COWP) gene with Polimerase Chain Reaction (PCR) method.

Results:
The results showed that 69 samples were positive for containing Cryptosporidium spp. oocysts and with Ziehl-Neelsen (ZN) staining to confirm the diagnosis, the staining results showed Cryptosporidium spp. oocysts dark pink with a clear cavity inside with a percentage of 95.65% in Rattus norvegicus and 61.03% in Rattus tanezumi. In residential and densely populated environments the percentage of Cryptosporidium spp. amounted to 66.66% and in the market environment amounted to 74.19%. Percentage of Cryptosporidium spp. in the North Surabaya region it was 42.85%, South Surabaya 100%, West Surabaya 37.5%, East Surabaya 81.39%, and Central Surabaya 65.38%. Molecular detection of Cryptosporidium spp. positive results were obtained using the Cryptosporidium oocyst wall protein (COWP) gene 550 bp.

Conclusion:
The high number of cases of cryptosporidiosis in wild rats This study aims to detect Cryptosporidium spp. infection in wild rats in Surabaya, East Java, Indonesia.
has the potential to be a reservoir for the spread of the disease. The Cryptosporidium spp can detected with oocyst wall protein (COWP) in 550 bp in wild rats in Surabaya, East Java, Indonesia.

Key words: COWP gene, Cryptosporidium spp., Wild rat, Ziehl-Neelsen, Zoonosis