Study traces history of giant brown rat to Sindh's coastal belt

A study conducted by Zoology Department of Peshawar University over increasing incidents of rat bites in Peshawar, has found that the rodent, brown rat (Rattus norvegicus), is an invasive species, which presumably arrived in the country via the port city of Karachi.
The study conducted by faculty and students of Zoology Department under the supervision of Assistant Professor Dr Farah Zaidi, reveals that black rat was mostly found in Pakistan, but the invasion of brown rat is a recent phenomenon and can be traced back to coastal areas of Sindh, especially Karachi.
From this point in time, the rat has established itself most probably via transportation route in other major cities of the country, adds the study. It may be mentioned here that for the last few years Peshawarities have been facing problem of rat bites due to sudden appearance of giant rats in the city. The issue became so serious that the City District Government had to conduct a campaign for killing of rats, but in vain.
The Water and Sanitation Service Peshawar, sanitary body of the city, created a post of `Rat killer' for getting rid of the rats, but the move also did not yield desired results. In the study, the researchers modelled geo-spatial distribution of rodent bites for risk assessment in Peshawar valley. The rodents are important vectors of many pathogens and reservoir host of at least 60 zoonotic diseases, the study warns.
Historically Rattus species (both black and brown rats) have been implicated in the emergence and spread of infectious diseases of human health importance such as plague, murine typhus, scrub typhus, leptospirosis and hemorrhagic fever. The study found that rodent bite activity is the greatest in the area, Peshawar valley, with maximum rodent infections. During research, it was found that from January 1 to August 31, 2016, 1747 cases of rat bites were reported in Peshawar's Lady Reading Hospital (LRH).
To estimate the potential risk of rat bite, researchers used a variety of presumably environmental variables that affect life cycles of the species and anthropogenic factors that affect the dispersal and distribution of the species. Climatic conditions including temperature, precipitations and humidity are major environmental factors deriving the demography of rats.
While, increasing urbanization, lack of land use planning and distance from water channels are anthropogenic factors for survival of the rodents. The study found target area (Peshawar) with maximum infestation that needs immediate control strategies. Most of the bite cases were reported from Peshawar and probability of occurrence was greatest in urban hubs (city areas).
Bulk of the rat bite cases were reported in old city of Peshawar, characterized by unhygienic sanitation practices and inadequate sewerage disposal. "An abnormally high number of rat bites cases are reported in district Peshawar and its peripheries during an eight month period,". This situation is alarming as rat bites are not numerous especially when compared with other animal bites," the study warns.
It also suggests for holding an exhaustive study to explore the rodent fauna of the region. The rising rate of biting expresses aggressive behaviour of the rat. In the conclusion, the study observed that bites by black and brown rats are an immediate health concern in Peshawar and its peripheries.
The study also laid stress for obtaining information on ecology, biology and behaviour of the species with knowledge about spatial distribution of rodent population for planning and implementation of effective control measures. The present study provides baseline information on ecology of rodents in Peshawar and thus can be utilized as a model for future control measures for ensuring public health.