Title: Plague of Athens
Content:  The Plague of Athens (, Loimos tôn Athênôn) was an epidemic that devastated the city-state of Athens in ancient Greece during the second year (430 BC) of the Peloponnesian War when an Athenian victory still seemed within reach. The plague killed an estimated 75,000 to 100,000 people, around one quarter of the population, and is believed to have entered Athens through Piraeus, the city's port and sole source of food and supplies. Much of the eastern Mediterranean also saw an outbreak of the disease, albeit with less impact. The plague had serious effects on Athens' society, resulting in a lack of adherence to laws and religious belief; in response laws became stricter, resulting in the punishment of non-citizens claiming to be Athenian. Among the victims of the plague was Pericles, the leader of Athens. The plague returned twice more, in 429 BC and in the winter of 427/426 BC. Some 30 pathogens have been suggested as having caused the plague.
Title: Plague of Athens
Content:  The plague was an unforeseen event that resulted in one of the largest recorded loss of life in ancient Greece as well as a breakdown of Athenian society. The balance of power between citizens had changed due to many of the rich dying and their fortunes being inherited by remaining relatives of the lower class. According to Thucydides, those who had become ill and survived were the most sympathetic to others suffering: believing that they could no longer succumb to any illness, a number of survivors offered to assist with the remaining sick. The plague had also contributed to Athens' overall loss of power and ability to expand. Many of the remaining Athenians were found to be metics 
Title: Pandemic
Content: Plague of Athens (430 to 426 BC): During the Peloponnesian War, typhoid fever killed a quarter of the Athenian troops and a quarter of the population. This disease fatally weakened the dominance of Athens, but the sheer virulence of the disease prevented its wider spread; i.e. it killed off its hosts at a rate faster than they could spread it. The exact cause of the plague was unknown for many years. In January 2006, researchers from the University of Athens analyzed teeth recovered from a mass grave underneath the city and confirmed the presence of bacteria responsible for typhoid. ; Antonine Plague (165 to 
Title: Plague of Athens
Content:  had the most contact with the sick. In overcrowded Athens, the disease killed an estimated 25% of the population. The sight of the burning funeral pyres of Athens caused the Spartans to withdraw their troops, being unwilling to risk contact with the diseased enemy. Many of Athens' infantry and expert seamen died. According to Thucydides, not until 415 BC had Athens recovered sufficiently to mount a major offensive, the disastrous Sicilian Expedition. The first corroboration of the plague was not revealed until 1994-95 where excavation revealed the first mass grave. Upon this discovery, Thucydides' accounts of the event as well as analysis of the remains had been used to try and identify the cause of the epidemic.
Title: Plague of Athens
Content:  The plague also caused religious uncertainty and doubt. Since the disease struck without regard to a person's piety toward the gods, people felt abandoned by the gods and there seemed to be no benefit to worshiping them. The temples themselves were sites of great misery, as refugees from the Athenian countryside had been forced to find accommodation in the temples. Soon the sacred buildings were filled with the dead and dying. The Athenians pointed to the plague as evidence that the gods favored Sparta, and this was supported by an oracle that Apollo himself (the god of disease and medicine) would fight for Sparta if they fought with all their might. An earlier oracle had warned that "A Dorian [Spartan] war will come, 
Title: Peloponnesian War
Content:  densely packed city, and in the long run, was a significant cause of its final defeat. The plague wiped out over 30,000 citizens, sailors and soldiers, including Pericles and his sons. Roughly one-third to two-thirds of the Athenian population died. Athenian manpower was correspondingly drastically reduced and even foreign mercenaries refused to hire themselves out to a city riddled with plague. The fear of plague was so widespread that the Spartan invasion of Attica was abandoned, their troops being unwilling to risk contact with the diseased enemy. After the death of Pericles, the Athenians turned somewhat against his conservative, defensive strategy 
Title: Plague of Athens
Content:  Historians have long tried to identify the disease behind the Plague of Athens. The disease has traditionally been considered an outbreak of the bubonic plague in its many forms, but reconsideration of the reported symptoms and epidemiology have led scholars to advance alternative explanations. These include typhus, smallpox, measles, and toxic shock syndrome. Based upon striking descriptive similarities with recent outbreaks in Africa, as well as the fact that the Athenian plague itself apparently came from Africa (as Thucydides recorded), Ebola or a related viral hemorrhagic fever has been considered. Given the possibility that profiles of a known disease may have changed over time, or that the plague was caused by a disease that no longer exists, the exact nature of the Athenian plague may never be known. In addition, crowding caused by the influx of refugees into the city led to inadequate food and water supplies and a probable proportionate increase in insects, lice, rats, and waste. These conditions would have encouraged more than one epidemic disease during the outbreak.
Title: Plague of Athens
Content:  had forged their documentation or had bribed officials to hide their original status. A number of these people were reduced to slaves once they were caught. This resulted in stricter laws dictating who could become an Athenian citizen, reducing both their number of potential soldiers and amount of political power, but also a decline in treatment and rights for metics in Athens. The plague dealt massive damage to Athens two years into the Peloponnesian War, from which it never recovered. Their political strength had weakened and morale among their armies as well as the citizens had fallen significantly. Athens would then go on to be defeated by Sparta and fall from being a major power in Ancient Greece.
Title: Plague of Athens
Content:  disease, and many citizens died. In the history of epidemics in war time, the 'Plague' of Athens is remarkable for the limitation of the affliction to one side as well as for its influence on the ultimate outcome of the war. In his History of the Peloponnesian War, the historian Thucydides, who was present and contracted the disease himself and survived, describes the epidemic. He writes of a disease coming from Ethiopia and passing through Egypt and Libya into the Greek world and spreading throughout the wider Mediterranean; a plague so severe and deadly that no one could recall anywhere its like, and physicians ignorant of its nature not only were helpless but themselves died the fastest, 
Title: 430 BC
Content: The army of Sparta loots Attica for a second time, but Pericles is not daunted and refuses to revise his initial strategy. Unwilling to engage the Spartan army in battle, he again leads a naval expedition to plunder the coasts of the Peloponnesus, this time taking 100 Athenian ships with him. ; Potidaea finally capitulates to the siege by Athenian forces in the winter. ; An outbreak of a plague hits Athens and the disease ravages the densely packed city (modern DNA analyses of material from ancient cemeteries suggest the mortal disease may have been typhus). The plague wipes out over 30,000 citizens, sailors, and soldiers as well as Pericles' two sons. Roughly one-quarter of the Athenian population dies. The fear of plague is so widespread that the Spartan invasion of Attica is abandoned, their troops being unwilling to risk contact with the diseased enemy. ; Pericles becomes ill from the plague but he recovers, temporarily. He is deposed from his position as General (or Strategos) but is later reappointed. 

Question: why was the plague that struck athens so devastating?
Answer: close quarters and poor hygiene.